dirmngr: Add basic libdns support

* dirmngr/dns.c: New file.
* dirmngr/dns.h: New file.
* dirmngr/Makefile.am (dirmngr_SOURCES): Add new files.
* dirmngr/dns-stuff.c: Include dns.h.xxx use libdns
(libdns): New global var for the libdns state.
(libdns_error_to_gpg_error): New.
(libdns_init): New.
(resolve_name_libdns): New.
(get_dns_cert_libdns): New stub.
(getsrv_libdns): New stub.
(get_dns_cname_libdns): New stub.

Signed-off-by: Justus Winter <justus@g10code.com>

1 files changed, 11152 insertions, 0 deletions

diff --git a/dirmngr/dns.c b/dirmngr/dns.c
new file mode 100644
index 000000000..f29158c2f
--- /dev/null
+++ b/dirmngr/dns.c
@@ -0,0 +1,11152 @@
+/* ==========================================================================
+ * dns.c - Recursive, Reentrant DNS Resolver.
+ * --------------------------------------------------------------------------
+ * Copyright (c) 2008, 2009, 2010, 2012-2016  William Ahern
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the
+ * "Software"), to deal in the Software without restriction, including
+ * without limitation the rights to use, copy, modify, merge, publish,
+ * distribute, sublicense, and/or sell copies of the Software, and to permit
+ * persons to whom the Software is furnished to do so, subject to the
+ * following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included
+ * in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
+ * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN
+ * NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
+ * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
+ * OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
+ * USE OR OTHER DEALINGS IN THE SOFTWARE.
+ * ==========================================================================
+ */
+#if HAVE_CONFIG_H
+#include "config.h"
+#elif !defined _GNU_SOURCE
+#define _GNU_SOURCE 1
+#endif
+
+#include <limits.h>		/* INT_MAX */
+#include <stdarg.h>		/* va_list va_start va_end */
+#include <stddef.h>		/* offsetof() */
+#ifdef _WIN32
+/* JW: This breaks our mingw build: #define uint32_t unsigned int */
+#else
+#include <stdint.h>		/* uint32_t */
+#endif
+#include <stdlib.h>		/* malloc(3) realloc(3) free(3) rand(3) random(3) arc4random(3) */
+#include <stdio.h>		/* FILE fopen(3) fclose(3) getc(3) rewind(3) vsnprintf(3) */
+#include <string.h>		/* memcpy(3) strlen(3) memmove(3) memchr(3) memcmp(3) strchr(3) strsep(3) strcspn(3) */
+#include <strings.h>		/* strcasecmp(3) strncasecmp(3) */
+#include <ctype.h>		/* isspace(3) isdigit(3) */
+#include <time.h>		/* time_t time(2) difftime(3) */
+#include <signal.h>		/* SIGPIPE sigemptyset(3) sigaddset(3) sigpending(2) sigprocmask(2) pthread_sigmask(3) sigtimedwait(2) */
+#include <errno.h>		/* errno EINVAL ENOENT */
+#undef NDEBUG
+#include <assert.h>		/* assert(3) */
+
+#if _WIN32
+#ifndef FD_SETSIZE
+#define FD_SETSIZE 256
+#endif
+#include <winsock2.h>
+#include <ws2tcpip.h>
+#else
+#include <sys/time.h>		/* gettimeofday(2) */
+#include <sys/types.h>		/* FD_SETSIZE socklen_t */
+#include <sys/select.h>		/* FD_ZERO FD_SET fd_set select(2) */
+#include <sys/socket.h>		/* AF_INET AF_INET6 AF_UNIX struct sockaddr struct sockaddr_in struct sockaddr_in6 socket(2) */
+#if defined(AF_UNIX)
+#include <sys/un.h>		/* struct sockaddr_un */
+#endif
+#include <fcntl.h>		/* F_SETFD F_GETFL F_SETFL O_NONBLOCK fcntl(2) */
+#include <unistd.h>		/* _POSIX_THREADS gethostname(3) close(2) */
+#include <poll.h>		/* POLLIN POLLOUT */
+#include <netinet/in.h>		/* struct sockaddr_in struct sockaddr_in6 */
+#include <arpa/inet.h>		/* inet_pton(3) inet_ntop(3) htons(3) ntohs(3) */
+#include <netdb.h>		/* struct addrinfo */
+#endif
+
+#include "dns.h"
+
+
+/*
+ * C O M P I L E R  V E R S I O N  &  F E A T U R E  D E T E C T I O N
+ *
+ * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
+
+#define DNS_GNUC_2VER(M, m, p) (((M) * 10000) + ((m) * 100) + (p))
+#define DNS_GNUC_PREREQ(M, m, p) (__GNUC__ > 0 && DNS_GNUC_2VER(__GNUC__, __GNUC_MINOR__, __GNUC_PATCHLEVEL__) >= DNS_GNUC_2VER((M), (m), (p)))
+
+#define DNS_MSC_2VER(M, m, p) ((((M) + 6) * 10000000) + ((m) * 1000000) + (p))
+#define DNS_MSC_PREREQ(M, m, p) (_MSC_VER_FULL > 0 && _MSC_VER_FULL >= DNS_MSC_2VER((M), (m), (p)))
+
+#define DNS_SUNPRO_PREREQ(M, m, p) (__SUNPRO_C > 0 && __SUNPRO_C >= 0x ## M ## m ## p)
+
+#if defined __has_builtin
+#define dns_has_builtin(x) __has_builtin(x)
+#else
+#define dns_has_builtin(x) 0
+#endif
+
+#if defined __has_extension
+#define dns_has_extension(x) __has_extension(x)
+#else
+#define dns_has_extension(x) 0
+#endif
+
+#ifndef HAVE___ASSUME
+#define HAVE___ASSUME DNS_MSC_PREREQ(8,0,0)
+#endif
+
+#ifndef HAVE___BUILTIN_TYPES_COMPATIBLE_P
+#define HAVE___BUILTIN_TYPES_COMPATIBLE_P (DNS_GNUC_PREREQ(3,1,1) || __clang__)
+#endif
+
+#ifndef HAVE___BUILTIN_UNREACHABLE
+#define HAVE___BUILTIN_UNREACHABLE (DNS_GNUC_PREREQ(4,5,0) || dns_has_builtin(__builtin_unreachable))
+#endif
+
+#ifndef HAVE_PRAGMA_MESSAGE
+#define HAVE_PRAGMA_MESSAGE (DNS_GNUC_PREREQ(4,4,0) || __clang__ || _MSC_VER)
+#endif
+
+
+/*
+ * C O M P I L E R  A N N O T A T I O N S
+ *
+ * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
+
+#if __GNUC__
+#define DNS_NOTUSED __attribute__((unused))
+#define DNS_NORETURN __attribute__((noreturn))
+#else
+#define DNS_NOTUSED
+#define DNS_NORETURN
+#endif
+
+#if __clang__
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wunused-parameter"
+#pragma clang diagnostic ignored "-Wmissing-field-initializers"
+#elif DNS_GNUC_PREREQ(4,6,0)
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wunused-parameter"
+#pragma GCC diagnostic ignored "-Wmissing-field-initializers"
+#endif
+
+
+/*
+ * S T A N D A R D  M A C R O S
+ *
+ * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
+
+#if HAVE___BUILTIN_TYPES_COMPATIBLE_P
+#define dns_same_type(a, b, def) __builtin_types_compatible_p(__typeof__ (a), __typeof__ (b))
+#else
+#define dns_same_type(a, b, def) (def)
+#endif
+#define dns_isarray(a) (!dns_same_type((a), (&(a)[0]), 0))
+/* NB: "_" field silences Sun Studio "zero-sized struct/union" error diagnostic */
+#define dns_inline_assert(cond) ((void)(sizeof (struct { int:-!(cond); int _; })))
+
+#if HAVE___ASSUME
+#define dns_assume(cond) __assume(cond)
+#elif HAVE___BUILTIN_UNREACHABLE
+#define dns_assume(cond) do { if (!(cond)) __builtin_unreachable(); } while (0)
+#else
+#define dns_assume(cond) do { (void)(cond); } while (0)
+#endif
+
+#ifndef lengthof
+#define lengthof(a) (dns_inline_assert(dns_isarray(a)), (sizeof (a) / sizeof (a)[0]))
+#endif
+
+#ifndef endof
+#define endof(a) (dns_inline_assert(dns_isarray(a)), &(a)[lengthof((a))])
+#endif
+
+
+/*
+ * M I S C E L L A N E O U S  C O M P A T
+ *
+ * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
+
+#if _WIN32 || _WIN64
+#define PRIuZ "Iu"
+#else
+#define PRIuZ "zu"
+#endif
+
+#ifndef DNS_THREAD_SAFE
+#if (defined _REENTRANT || defined _THREAD_SAFE) && _POSIX_THREADS > 0
+#define DNS_THREAD_SAFE 1
+#else
+#define DNS_THREAD_SAFE 0
+#endif
+#endif
+
+#ifndef HAVE__STATIC_ASSERT
+#define HAVE__STATIC_ASSERT \
+	(dns_has_extension(c_static_assert) || DNS_GNUC_PREREQ(4,6,0) || \
+	 __C11FEATURES__ || __STDC_VERSION__ >= 201112L)
+#endif
+
+#ifndef HAVE_STATIC_ASSERT
+#if DNS_GNUC_PREREQ(0,0,0) && !DNS_GNUC_PREREQ(4,6,0)
+#define HAVE_STATIC_ASSERT 0 /* glibc doesn't check GCC version */
+#else
+#define HAVE_STATIC_ASSERT (defined static_assert)
+#endif
+#endif
+
+#if HAVE_STATIC_ASSERT
+#define dns_static_assert(cond, msg) static_assert(cond, msg)
+#elif HAVE__STATIC_ASSERT
+#define dns_static_assert(cond, msg) _Static_assert(cond, msg)
+#else
+#define dns_static_assert(cond, msg) extern char DNS_PP_XPASTE(dns_assert_, __LINE__)[sizeof (int[1 - 2*!(cond)])]
+#endif
+
+
+/*
+ * D E B U G  M A C R O S
+ *
+ * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
+
+int *dns_debug_p(void) {
+	static int debug;
+
+	return &debug;
+} /* dns_debug_p() */
+
+#if DNS_DEBUG
+
+#undef DNS_DEBUG
+#define DNS_DEBUG dns_debug
+
+#define DNS_SAY_(fmt, ...) \
+	do { if (DNS_DEBUG > 0) fprintf(stderr, fmt "%.1s", __func__, __LINE__, __VA_ARGS__); } while (0)
+#define DNS_SAY(...) DNS_SAY_("@@ (%s:%d) " __VA_ARGS__, "\n")
+#define DNS_HAI DNS_SAY("HAI")
+
+#define DNS_SHOW_(P, fmt, ...)	do {					\
+	if (DNS_DEBUG > 1) {						\
+	fprintf(stderr, "@@ BEGIN * * * * * * * * * * * *\n");		\
+	fprintf(stderr, "@@ " fmt "%.0s\n", __VA_ARGS__);		\
+	dns_p_dump((P), stderr);					\
+	fprintf(stderr, "@@ END * * * * * * * * * * * * *\n\n");	\
+	}								\
+} while (0)
+
+#define DNS_SHOW(...)	DNS_SHOW_(__VA_ARGS__, "")
+
+#else /* !DNS_DEBUG */
+
+#undef DNS_DEBUG
+#define DNS_DEBUG 0
+
+#define DNS_SAY(...)
+#define DNS_HAI
+#define DNS_SHOW(...)
+
+#endif /* DNS_DEBUG */
+
+#define DNS_CARP(...) DNS_SAY(__VA_ARGS__)
+
+
+/*
+ * V E R S I O N  R O U T I N E S
+ *
+ * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
+
+const char *dns_vendor(void) {
+	return DNS_VENDOR;
+} /* dns_vendor() */
+
+
+int dns_v_rel(void) {
+	return DNS_V_REL;
+} /* dns_v_rel() */
+
+
+int dns_v_abi(void) {
+	return DNS_V_ABI;
+} /* dns_v_abi() */
+
+
+int dns_v_api(void) {
+	return DNS_V_API;
+} /* dns_v_api() */
+
+
+/*
+ * E R R O R  R O U T I N E S
+ *
+ * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
+
+#if _WIN32
+
+#define DNS_EINTR	WSAEINTR
+#define DNS_EINPROGRESS	WSAEINPROGRESS
+#define DNS_EISCONN	WSAEISCONN
+#define DNS_EWOULDBLOCK	WSAEWOULDBLOCK
+#define DNS_EALREADY	WSAEALREADY
+#define DNS_EAGAIN	EAGAIN
+#define DNS_ETIMEDOUT	WSAETIMEDOUT
+
+#define dns_syerr()	((int)GetLastError())
+#define dns_soerr()	((int)WSAGetLastError())
+
+#else
+
+#define DNS_EINTR	EINTR
+#define DNS_EINPROGRESS	EINPROGRESS
+#define DNS_EISCONN	EISCONN
+#define DNS_EWOULDBLOCK	EWOULDBLOCK
+#define DNS_EALREADY	EALREADY
+#define DNS_EAGAIN	EAGAIN
+#define DNS_ETIMEDOUT	ETIMEDOUT
+
+#define dns_syerr()	errno
+#define dns_soerr()	errno
+
+#endif
+
+
+const char *dns_strerror(int error) {
+	switch (error) {
+	case DNS_ENOBUFS:
+		return "DNS packet buffer too small";
+	case DNS_EILLEGAL:
+		return "Illegal DNS RR name or data";
+	case DNS_EORDER:
+		return "Attempt to push RR out of section order";
+	case DNS_ESECTION:
+		return "Invalid section specified";
+	case DNS_EUNKNOWN:
+		return "Unknown DNS error";
+	case DNS_EADDRESS:
+		return "Invalid textual address form";
+	case DNS_ENOQUERY:
+		return "Bad execution state (missing query packet)";
+	case DNS_ENOANSWER:
+		return "Bad execution state (missing answer packet)";
+	case DNS_EFETCHED:
+		return "Answer already fetched";
+	case DNS_ESERVICE:
+		return "The service passed was not recognized for the specified socket type";
+	case DNS_ENONAME:
+		return "The name does not resolve for the supplied parameters";
+	case DNS_EFAIL:
+		return "A non-recoverable error occurred when attempting to resolve the name";
+	case DNS_ECONNFIN:
+		return "Connection closed";
+	case DNS_EVERIFY:
+		return "Reply failed verification";
+	default:
+		return strerror(error);
+	} /* switch() */
+} /* dns_strerror() */
+
+
+/*
+ * A T O M I C  R O U T I N E S
+ *
+ * Use GCC's __atomic built-ins if possible. Unlike the __sync built-ins, we
+ * can use the preprocessor to detect API and, more importantly, ISA
+ * support. We want to avoid linking headaches where the API depends on an
+ * external library if the ISA (e.g. i386) doesn't support lockless
+ * operation.
+ *
+ * TODO: Support C11's atomic API. Although that may require some finesse
+ * with how we define some public types, such as dns_atomic_t and struct
+ * dns_resolv_conf.
+ *
+ * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
+
+#ifndef HAVE___ATOMIC_FETCH_ADD
+#define HAVE___ATOMIC_FETCH_ADD (defined __ATOMIC_RELAXED)
+#endif
+
+#ifndef HAVE___ATOMIC_FETCH_SUB
+#define HAVE___ATOMIC_FETCH_SUB HAVE___ATOMIC_FETCH_ADD
+#endif
+
+#ifndef DNS_ATOMIC_FETCH_ADD
+#if HAVE___ATOMIC_FETCH_ADD && __GCC_ATOMIC_LONG_LOCK_FREE == 2
+#define DNS_ATOMIC_FETCH_ADD(i) __atomic_fetch_add((i), 1, __ATOMIC_RELAXED)
+#else
+#pragma message("no atomic_fetch_add available")
+#define DNS_ATOMIC_FETCH_ADD(i) ((*(i))++)
+#endif
+#endif
+
+#ifndef DNS_ATOMIC_FETCH_SUB
+#if HAVE___ATOMIC_FETCH_SUB && __GCC_ATOMIC_LONG_LOCK_FREE == 2
+#define DNS_ATOMIC_FETCH_SUB(i) __atomic_fetch_sub((i), 1, __ATOMIC_RELAXED)
+#else
+#pragma message("no atomic_fetch_sub available")
+#define DNS_ATOMIC_FETCH_SUB(i) ((*(i))--)
+#endif
+#endif
+
+static inline unsigned dns_atomic_fetch_add(dns_atomic_t *i) {
+	return DNS_ATOMIC_FETCH_ADD(i);
+} /* dns_atomic_fetch_add() */
+
+
+static inline unsigned dns_atomic_fetch_sub(dns_atomic_t *i) {
+	return DNS_ATOMIC_FETCH_SUB(i);
+} /* dns_atomic_fetch_sub() */
+
+
+/*
+ * C R Y P T O  R O U T I N E S
+ *
+ * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
+
+/*
+ * P R N G
+ */
+
+#ifndef DNS_RANDOM
+#if defined(HAVE_ARC4RANDOM)	\
+ || defined(__OpenBSD__)	\
+ || defined(__FreeBSD__)	\
+ || defined(__NetBSD__)		\
+ || defined(__APPLE__)
+#define DNS_RANDOM	arc4random
+#elif __linux
+#define DNS_RANDOM	random
+#else
+#define DNS_RANDOM	rand
+#endif
+#endif
+
+#define DNS_RANDOM_arc4random	1
+#define DNS_RANDOM_random	2
+#define DNS_RANDOM_rand		3
+#define DNS_RANDOM_RAND_bytes	4
+
+#define DNS_RANDOM_OPENSSL	(DNS_RANDOM_RAND_bytes == DNS_PP_XPASTE(DNS_RANDOM_, DNS_RANDOM))
+
+#if DNS_RANDOM_OPENSSL
+#include <openssl/rand.h>
+#endif
+
+static unsigned dns_random_(void) {
+#if DNS_RANDOM_OPENSSL
+	unsigned r;
+	_Bool ok;
+
+	ok = (1 == RAND_bytes((unsigned char *)&r, sizeof r));
+	assert(ok && "1 == RAND_bytes()");
+
+	return r;
+#else
+	return DNS_RANDOM();
+#endif
+} /* dns_random_() */
+
+dns_random_f **dns_random_p(void) {
+	static dns_random_f *random_f = &dns_random_;
+
+	return &random_f;
+} /* dns_random_p() */
+
+
+/*
+ * P E R M U T A T I O N  G E N E R A T O R
+ */
+
+#define DNS_K_TEA_KEY_SIZE	16
+#define DNS_K_TEA_BLOCK_SIZE	8
+#define DNS_K_TEA_CYCLES	32
+#define DNS_K_TEA_MAGIC		0x9E3779B9U
+
+struct dns_k_tea {
+	uint32_t key[DNS_K_TEA_KEY_SIZE / sizeof (uint32_t)];
+	unsigned cycles;
+}; /* struct dns_k_tea */
+
+
+static void dns_k_tea_init(struct dns_k_tea *tea, uint32_t key[], unsigned cycles) {
+	memcpy(tea->key, key, sizeof tea->key);
+
+	tea->cycles	= (cycles)? cycles : DNS_K_TEA_CYCLES;
+} /* dns_k_tea_init() */
+
+
+static void dns_k_tea_encrypt(struct dns_k_tea *tea, uint32_t v[], uint32_t *w) {
+	uint32_t y, z, sum, n;
+
+	y	= v[0];
+	z	= v[1];
+	sum	= 0;
+
+	for (n = 0; n < tea->cycles; n++) {
+		sum	+= DNS_K_TEA_MAGIC;
+		y	+= ((z << 4) + tea->key[0]) ^ (z + sum) ^ ((z >> 5) + tea->key[1]);
+		z	+= ((y << 4) + tea->key[2]) ^ (y + sum) ^ ((y >> 5) + tea->key[3]);
+	}
+
+	w[0]	= y;
+	w[1]	= z;
+
+	return /* void */;
+} /* dns_k_tea_encrypt() */
+
+
+/*
+ * Permutation generator, based on a Luby-Rackoff Feistel construction.
+ *
+ * Specifically, this is a generic balanced Feistel block cipher using TEA
+ * (another block cipher) as the pseudo-random function, F. At best it's as
+ * strong as F (TEA), notwithstanding the seeding. F could be AES, SHA-1, or
+ * perhaps Bernstein's Salsa20 core; I am naively trying to keep things
+ * simple.
+ *
+ * The generator can create a permutation of any set of numbers, as long as
+ * the size of the set is an even power of 2. This limitation arises either
+ * out of an inherent property of balanced Feistel constructions, or by my
+ * own ignorance. I'll tackle an unbalanced construction after I wrap my
+ * head around Schneier and Kelsey's paper.
+ *
+ * CAVEAT EMPTOR. IANAC.
+ */
+#define DNS_K_PERMUTOR_ROUNDS	8
+
+struct dns_k_permutor {
+	unsigned stepi, length, limit;
+	unsigned shift, mask, rounds;
+
+	struct dns_k_tea tea;
+}; /* struct dns_k_permutor */
+
+
+static inline unsigned dns_k_permutor_powof(unsigned n) {
+	unsigned m, i = 0;
+
+	for (m = 1; m < n; m <<= 1, i++)
+		;;
+
+	return i;
+} /* dns_k_permutor_powof() */
+
+static void dns_k_permutor_init(struct dns_k_permutor *p, unsigned low, unsigned high) {
+	uint32_t key[DNS_K_TEA_KEY_SIZE / sizeof (uint32_t)];
+	unsigned width, i;
+
+	p->stepi	= 0;
+
+	p->length	= (high - low) + 1;
+	p->limit	= high;
+
+	width		= dns_k_permutor_powof(p->length);
+	width		+= width % 2;
+
+	p->shift	= width / 2;
+	p->mask		= (1U << p->shift) - 1;
+	p->rounds	= DNS_K_PERMUTOR_ROUNDS;
+
+	for (i = 0; i < lengthof(key); i++)
+		key[i]	= dns_random();
+
+	dns_k_tea_init(&p->tea, key, 0);
+
+	return /* void */;
+} /* dns_k_permutor_init() */
+
+
+static unsigned dns_k_permutor_F(struct dns_k_permutor *p, unsigned k, unsigned x) {
+	uint32_t in[DNS_K_TEA_BLOCK_SIZE / sizeof (uint32_t)], out[DNS_K_TEA_BLOCK_SIZE / sizeof (uint32_t)];
+
+	memset(in, '\0', sizeof in);
+
+	in[0]	= k;
+	in[1]	= x;
+
+	dns_k_tea_encrypt(&p->tea, in, out);
+
+	return p->mask & out[0];
+} /* dns_k_permutor_F() */
+
+
+static unsigned dns_k_permutor_E(struct dns_k_permutor *p, unsigned n) {
+	unsigned l[2], r[2];
+	unsigned i;
+
+	i	= 0;
+	l[i]	= p->mask & (n >> p->shift);
+	r[i]	= p->mask & (n >> 0);
+
+	do {
+		l[(i + 1) % 2]	= r[i % 2];
+		r[(i + 1) % 2]	= l[i % 2] ^ dns_k_permutor_F(p, i, r[i % 2]);
+
+		i++;
+	} while (i < p->rounds - 1);
+
+	return ((l[i % 2] & p->mask) << p->shift) | ((r[i % 2] & p->mask) << 0);
+} /* dns_k_permutor_E() */
+
+
+DNS_NOTUSED static unsigned dns_k_permutor_D(struct dns_k_permutor *p, unsigned n) {
+	unsigned l[2], r[2];
+	unsigned i;
+
+	i		= p->rounds - 1;
+	l[i % 2]	= p->mask & (n >> p->shift);
+	r[i % 2]	= p->mask & (n >> 0);
+
+	do {
+		i--;
+
+		r[i % 2]	= l[(i + 1) % 2];
+		l[i % 2]	= r[(i + 1) % 2] ^ dns_k_permutor_F(p, i, l[(i + 1) % 2]);
+	} while (i > 0);
+
+	return ((l[i % 2] & p->mask) << p->shift) | ((r[i % 2] & p->mask) << 0);
+} /* dns_k_permutor_D() */
+
+
+static unsigned dns_k_permutor_step(struct dns_k_permutor *p) {
+	unsigned n;
+
+	do {
+		n	= dns_k_permutor_E(p, p->stepi++);
+	} while (n >= p->length);
+
+	return n + (p->limit + 1 - p->length);
+} /* dns_k_permutor_step() */
+
+
+/*
+ * Simple permutation box. Useful for shuffling rrsets from an iterator.
+ * Uses AES s-box to provide good diffusion.
+ *
+ * Seems to pass muster under runs test.
+ *
+ * $ for i in 0 1 2 3 4 5 6 7 8 9; do ./dns shuffle-16 > /tmp/out; done
+ * $ R -q -f /dev/stdin 2>/dev/null <<-EOF | awk '/p-value/{ print $8 }'
+ * 	library(lawstat)
+ * 	runs.test(scan(file="/tmp/out"))
+ * EOF
+ */
+static unsigned short dns_k_shuffle16(unsigned short n, unsigned s) {
+	static const unsigned char sbox[256] =
+	{ 0x63, 0x7c, 0x77, 0x7b, 0xf2, 0x6b, 0x6f, 0xc5,
+	  0x30, 0x01, 0x67, 0x2b, 0xfe, 0xd7, 0xab, 0x76,
+	  0xca, 0x82, 0xc9, 0x7d, 0xfa, 0x59, 0x47, 0xf0,
+	  0xad, 0xd4, 0xa2, 0xaf, 0x9c, 0xa4, 0x72, 0xc0,
+	  0xb7, 0xfd, 0x93, 0x26, 0x36, 0x3f, 0xf7, 0xcc,
+	  0x34, 0xa5, 0xe5, 0xf1, 0x71, 0xd8, 0x31, 0x15,
+	  0x04, 0xc7, 0x23, 0xc3, 0x18, 0x96, 0x05, 0x9a,
+	  0x07, 0x12, 0x80, 0xe2, 0xeb, 0x27, 0xb2, 0x75,
+	  0x09, 0x83, 0x2c, 0x1a, 0x1b, 0x6e, 0x5a, 0xa0,
+	  0x52, 0x3b, 0xd6, 0xb3, 0x29, 0xe3, 0x2f, 0x84,
+	  0x53, 0xd1, 0x00, 0xed, 0x20, 0xfc, 0xb1, 0x5b,
+	  0x6a, 0xcb, 0xbe, 0x39, 0x4a, 0x4c, 0x58, 0xcf,
+	  0xd0, 0xef, 0xaa, 0xfb, 0x43, 0x4d, 0x33, 0x85,
+	  0x45, 0xf9, 0x02, 0x7f, 0x50, 0x3c, 0x9f, 0xa8,
+	  0x51, 0xa3, 0x40, 0x8f, 0x92, 0x9d, 0x38, 0xf5,
+	  0xbc, 0xb6, 0xda, 0x21, 0x10, 0xff, 0xf3, 0xd2,
+	  0xcd, 0x0c, 0x13, 0xec, 0x5f, 0x97, 0x44, 0x17,
+	  0xc4, 0xa7, 0x7e, 0x3d, 0x64, 0x5d, 0x19, 0x73,
+	  0x60, 0x81, 0x4f, 0xdc, 0x22, 0x2a, 0x90, 0x88,
+	  0x46, 0xee, 0xb8, 0x14, 0xde, 0x5e, 0x0b, 0xdb,
+	  0xe0, 0x32, 0x3a, 0x0a, 0x49, 0x06, 0x24, 0x5c,
+	  0xc2, 0xd3, 0xac, 0x62, 0x91, 0x95, 0xe4, 0x79,
+	  0xe7, 0xc8, 0x37, 0x6d, 0x8d, 0xd5, 0x4e, 0xa9,
+	  0x6c, 0x56, 0xf4, 0xea, 0x65, 0x7a, 0xae, 0x08,
+	  0xba, 0x78, 0x25, 0x2e, 0x1c, 0xa6, 0xb4, 0xc6,
+	  0xe8, 0xdd, 0x74, 0x1f, 0x4b, 0xbd, 0x8b, 0x8a,
+	  0x70, 0x3e, 0xb5, 0x66, 0x48, 0x03, 0xf6, 0x0e,
+	  0x61, 0x35, 0x57, 0xb9, 0x86, 0xc1, 0x1d, 0x9e,
+	  0xe1, 0xf8, 0x98, 0x11, 0x69, 0xd9, 0x8e, 0x94,
+	  0x9b, 0x1e, 0x87, 0xe9, 0xce, 0x55, 0x28, 0xdf,
+	  0x8c, 0xa1, 0x89, 0x0d, 0xbf, 0xe6, 0x42, 0x68,
+	  0x41, 0x99, 0x2d, 0x0f, 0xb0, 0x54, 0xbb, 0x16 };
+	unsigned char a, b;
+	unsigned i;
+
+	a = 0xff & (n >> 0);
+	b = 0xff & (n >> 8);
+
+	for (i = 0; i < 4; i++) {
+		a ^= 0xff & s;
+		a = sbox[a] ^ b;
+		b = sbox[b] ^ a;
+		s >>= 8;
+	}
+
+	return ((0xff00 & (a << 8)) | (0x00ff & (b << 0)));
+} /* dns_k_shuffle16() */
+
+/*
+ * S T A T E  M A C H I N E  R O U T I N E S
+ *
+ * Application code should define DNS_SM_RESTORE and DNS_SM_SAVE, and the
+ * local variable pc.
+ *
+ * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
+
+#define DNS_SM_ENTER \
+	do { \
+	static const int pc0 = __LINE__; \
+	DNS_SM_RESTORE; \
+	switch (pc0 + pc) { \
+	case __LINE__: (void)0
+
+#define DNS_SM_SAVE_AND_DO(do_statement) \
+	do { \
+		pc = __LINE__ - pc0; \
+		DNS_SM_SAVE; \
+		do_statement; \
+		case __LINE__: (void)0; \
+	} while (0)
+
+#define DNS_SM_YIELD(rv) \
+	DNS_SM_SAVE_AND_DO(return (rv))
+
+#define DNS_SM_EXIT \
+	do { goto leave; } while (0)
+
+#define DNS_SM_LEAVE \
+	leave: (void)0; \
+	DNS_SM_SAVE_AND_DO(break); \
+	} \
+	} while (0)
+
+/*
+ * U T I L I T Y  R O U T I N E S
+ *
+ * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
+
+#define DNS_MAXINTERVAL 300
+
+struct dns_clock {
+	time_t sample, elapsed;
+}; /* struct dns_clock */
+
+static void dns_begin(struct dns_clock *clk) {
+	clk->sample = time(0);
+	clk->elapsed = 0;
+} /* dns_begin() */
+
+static time_t dns_elapsed(struct dns_clock *clk) {
+	time_t curtime;
+
+	if ((time_t)-1 == time(&curtime))
+		return clk->elapsed;
+
+	if (curtime > clk->sample)
+		clk->elapsed += (time_t)DNS_PP_MIN(difftime(curtime, clk->sample), DNS_MAXINTERVAL);
+
+	clk->sample = curtime;
+
+	return clk->elapsed;
+} /* dns_elapsed() */
+
+
+DNS_NOTUSED static size_t dns_strnlen(const char *src, size_t m) {
+	size_t n = 0;
+
+	while (*src++ && n < m)
+		++n;
+
+	return n;
+} /* dns_strnlen() */
+
+
+DNS_NOTUSED static size_t dns_strnlcpy(char *dst, size_t lim, const char *src, size_t max) {
+	size_t len = dns_strnlen(src, max), n;
+
+	if (lim > 0) {
+		n = DNS_PP_MIN(lim - 1, len);
+		memcpy(dst, src, n);
+		dst[n] = '\0';
+	}
+
+	return len;
+} /* dns_strnlcpy() */
+
+
+#define DNS_HAVE_SOCKADDR_UN (defined AF_UNIX && !defined _WIN32)
+
+static size_t dns_af_len(int af) {
+	static const size_t table[AF_MAX]	= {
+		[AF_INET6]	= sizeof (struct sockaddr_in6),
+		[AF_INET]	= sizeof (struct sockaddr_in),
+#if DNS_HAVE_SOCKADDR_UN
+		[AF_UNIX]	= sizeof (struct sockaddr_un),
+#endif
+	};
+
+	return table[af];
+} /* dns_af_len() */
+
+#define dns_sa_family(sa)	(((struct sockaddr *)(sa))->sa_family)
+
+#define dns_sa_len(sa)		dns_af_len(dns_sa_family(sa))
+
+
+#define DNS_SA_NOPORT	&dns_sa_noport
+static unsigned short dns_sa_noport;
+
+static unsigned short *dns_sa_port(int af, void *sa) {
+	switch (af) {
+	case AF_INET6:
+		return &((struct sockaddr_in6 *)sa)->sin6_port;
+	case AF_INET:
+		return &((struct sockaddr_in *)sa)->sin_port;
+	default:
+		return DNS_SA_NOPORT;
+	}
+} /* dns_sa_port() */
+
+
+static void *dns_sa_addr(int af, const void *sa, socklen_t *size) {
+	switch (af) {
+	case AF_INET6: {
+		struct in6_addr *in6 = &((struct sockaddr_in6 *)sa)->sin6_addr;
+
+		if (size)
+			*size = sizeof *in6;
+
+		return in6;
+	}
+	case AF_INET: {
+		struct in_addr *in = &((struct sockaddr_in *)sa)->sin_addr;
+
+		if (size)
+			*size = sizeof *in;
+
+		return in;
+	}
+	default:
+		if (size)
+			*size = 0;
+
+		return 0;
+	}
+} /* dns_sa_addr() */
+
+
+#if DNS_HAVE_SOCKADDR_UN
+#define DNS_SUNPATHMAX (sizeof ((struct sockaddr_un *)0)->sun_path)
+#endif
+
+DNS_NOTUSED static void *dns_sa_path(void *sa, socklen_t *size) {
+	switch (dns_sa_family(sa)) {
+#if DNS_HAVE_SOCKADDR_UN
+	case AF_UNIX: {
+		char *path = ((struct sockaddr_un *)sa)->sun_path;
+
+		if (size)
+			*size = dns_strnlen(path, DNS_SUNPATHMAX);
+
+		return path;
+	}
+#endif
+	default:
+		if (size)
+			*size = 0;
+
+		return NULL;
+	}
+} /* dns_sa_path() */
+
+
+static int dns_sa_cmp(void *a, void *b) {
+	int cmp, af;
+
+	if ((cmp = dns_sa_family(a) - dns_sa_family(b)))
+		return cmp;
+
+	switch ((af = dns_sa_family(a))) {
+	case AF_INET: {
+		struct in_addr *a4, *b4;
+
+		if ((cmp = htons(*dns_sa_port(af, a)) - htons(*dns_sa_port(af, b))))
+			return cmp;
+
+		a4 = dns_sa_addr(af, a, NULL);
+		b4 = dns_sa_addr(af, b, NULL);
+
+		if (ntohl(a4->s_addr) < ntohl(b4->s_addr))
+			return -1;
+		if (ntohl(a4->s_addr) > ntohl(b4->s_addr))
+			return 1;
+
+		return 0;
+	}
+	case AF_INET6: {
+		struct in6_addr *a6, *b6;
+		size_t i;
+
+		if ((cmp = htons(*dns_sa_port(af, a)) - htons(*dns_sa_port(af, b))))
+			return cmp;
+
+		a6 = dns_sa_addr(af, a, NULL);
+		b6 = dns_sa_addr(af, b, NULL);
+
+		/* XXX: do we need to use in6_clearscope()? */
+		for (i = 0; i < sizeof a6->s6_addr; i++) {
+			if ((cmp = a6->s6_addr[i] - b6->s6_addr[i]))
+				return cmp;
+		}
+
+		return 0;
+	}
+#if DNS_HAVE_SOCKADDR_UN
+	case AF_UNIX: {
+		char a_path[DNS_SUNPATHMAX + 1], b_path[sizeof a_path];
+
+		dns_strnlcpy(a_path, sizeof a_path, dns_sa_path(a, NULL), DNS_SUNPATHMAX);
+		dns_strnlcpy(b_path, sizeof b_path, dns_sa_path(b, NULL), DNS_SUNPATHMAX);
+
+		return strcmp(a_path, b_path);
+	}
+#endif
+	default:
+		return -1;
+	}
+} /* dns_sa_cmp() */
+
+
+#if _WIN32
+static int dns_inet_pton(int af, const void *src, void *dst) {
+	union { struct sockaddr_in sin; struct sockaddr_in6 sin6; } u;
+
+	u.sin.sin_family	= af;
+
+	if (0 != WSAStringToAddressA((void *)src, af, (void *)0, (struct sockaddr *)&u, &(int){ sizeof u }))
+		return -1;
+
+	switch (af) {
+	case AF_INET6:
+		*(struct in6_addr *)dst	= u.sin6.sin6_addr;
+
+		return 1;
+	case AF_INET:
+		*(struct in_addr *)dst	= u.sin.sin_addr;
+
+		return 1;
+	default:
+		return 0;
+	}
+} /* dns_inet_pton() */
+
+static const char *dns_inet_ntop(int af, const void *src, void *dst, unsigned long lim) {
+	union { struct sockaddr_in sin; struct sockaddr_in6 sin6; } u;
+
+	/* NOTE: WSAAddressToString will print .sin_port unless zeroed. */
+	memset(&u, 0, sizeof u);
+
+	u.sin.sin_family	= af;
+
+	switch (af) {
+	case AF_INET6:
+		u.sin6.sin6_addr	= *(struct in6_addr *)src;
+		break;
+	case AF_INET:
+		u.sin.sin_addr		= *(struct in_addr *)src;
+
+		break;
+	default:
+		return 0;
+	}
+
+	if (0 != WSAAddressToStringA((struct sockaddr *)&u, dns_sa_len(&u), (void *)0, dst, &lim))
+		return 0;
+
+	return dst;
+} /* dns_inet_ntop() */
+#else
+#define dns_inet_pton(...)	inet_pton(__VA_ARGS__)
+#define dns_inet_ntop(...)	inet_ntop(__VA_ARGS__)
+#endif
+
+
+static dns_error_t dns_pton(int af, const void *src, void *dst) {
+	switch (dns_inet_pton(af, src, dst)) {
+	case 1:
+		return 0;
+	case -1:
+		return dns_soerr();
+	default:
+		return DNS_EADDRESS;
+	}
+} /* dns_pton() */
+
+
+static dns_error_t dns_ntop(int af, const void *src, void *dst, unsigned long lim) {
+	return (dns_inet_ntop(af, src, dst, lim))? 0 : dns_soerr();
+} /* dns_ntop() */
+
+
+size_t dns_strlcpy(char *dst, const char *src, size_t lim) {
+	char *d		= dst;
+	char *e		= &dst[lim];
+	const char *s	= src;
+
+	if (d < e) {
+		do {
+			if ('\0' == (*d++ = *s++))
+				return s - src - 1;
+		} while (d < e);
+
+		d[-1]	= '\0';
+	}
+
+	while (*s++ != '\0')
+		;;
+
+	return s - src - 1;
+} /* dns_strlcpy() */
+
+
+size_t dns_strlcat(char *dst, const char *src, size_t lim) {
+	char *d = memchr(dst, '\0', lim);
+	char *e = &dst[lim];
+	const char *s = src;
+	const char *p;
+
+	if (d && d < e) {
+		do {
+			if ('\0' == (*d++ = *s++))
+				return d - dst - 1;
+		} while (d < e);
+
+		d[-1] = '\0';
+	}
+
+	p = s;
+
+	while (*s++ != '\0')
+		;;
+
+	return lim + (s - p - 1);
+} /* dns_strlcat() */
+
+
+static void *dns_reallocarray(void *p, size_t nmemb, size_t size, dns_error_t *error) {
+	void *rp;
+
+	if (nmemb > 0 && SIZE_MAX / nmemb < size) {
+		*error = EOVERFLOW;
+		return NULL;
+	}
+
+	if (!(rp = realloc(p, nmemb * size)))
+		*error = (errno)? errno : EINVAL;
+
+	return rp;
+} /* dns_reallocarray() */
+
+
+#if _WIN32
+
+static char *dns_strsep(char **sp, const char *delim) {
+	char *p;
+
+	if (!(p = *sp))
+		return 0;
+
+	*sp += strcspn(p, delim);
+
+	if (**sp != '\0') {
+		**sp = '\0';
+		++*sp;
+	} else
+		*sp = NULL;
+
+	return p;
+} /* dns_strsep() */
+
+#else
+#define dns_strsep(...)	strsep(__VA_ARGS__)
+#endif
+
+
+#if _WIN32
+#define strcasecmp(...)		_stricmp(__VA_ARGS__)
+#define strncasecmp(...)	_strnicmp(__VA_ARGS__)
+#endif
+
+
+static inline _Bool dns_isalpha(unsigned char c) {
+	return isalpha(c);
+} /* dns_isalpha() */
+
+static inline _Bool dns_isdigit(unsigned char c) {
+	return isdigit(c);
+} /* dns_isdigit() */
+
+static inline _Bool dns_isalnum(unsigned char c) {
+	return isalnum(c);
+} /* dns_isalnum() */
+
+static inline _Bool dns_isspace(unsigned char c) {
+	return isspace(c);
+} /* dns_isspace() */
+
+static inline _Bool dns_isgraph(unsigned char c) {
+	return isgraph(c);
+} /* dns_isgraph() */
+
+
+static int dns_poll(int fd, short events, int timeout) {
+	fd_set rset, wset;
+
+	if (!events)
+		return 0;
+
+	assert(fd >= 0 && (unsigned)fd < FD_SETSIZE);
+
+	FD_ZERO(&rset);
+	FD_ZERO(&wset);
+
+	if (events & DNS_POLLIN)
+		FD_SET(fd, &rset);
+
+	if (events & DNS_POLLOUT)
+		FD_SET(fd, &wset);
+
+	select(fd + 1, &rset, &wset, 0, (timeout >= 0)? &(struct timeval){ timeout, 0 } : NULL);
+
+	return 0;
+} /* dns_poll() */
+
+
+#if !_WIN32
+DNS_NOTUSED static int dns_sigmask(int how, const sigset_t *set, sigset_t *oset) {
+#if DNS_THREAD_SAFE
+	return pthread_sigmask(how, set, oset);
+#else
+	return (0 == sigprocmask(how, set, oset))? 0 : errno;
+#endif
+} /* dns_sigmask() */
+#endif
+
+
+static size_t dns_send(int fd, const void *src, size_t len, int flags, dns_error_t *error) {
+	long n = send(fd, src, len, flags);
+
+	if (n < 0) {
+		*error = dns_soerr();
+		return 0;
+	} else {
+		*error = 0;
+		return n;
+	}
+} /* dns_send() */
+
+static size_t dns_recv(int fd, void *dst, size_t lim, int flags, dns_error_t *error) {
+	long n = recv(fd, dst, lim, flags);
+
+	if (n < 0) {
+		*error = dns_soerr();
+		return 0;
+	} else if (n == 0) {
+		*error = (lim > 0)? DNS_ECONNFIN : EINVAL;
+		return 0;
+	} else {
+		*error = 0;
+		return n;
+	}
+} /* dns_recv() */
+
+static size_t dns_send_nopipe(int fd, const void *src, size_t len, int flags, dns_error_t *_error) {
+#if _WIN32 || !defined SIGPIPE || defined SO_NOSIGPIPE
+	return dns_send(fd, src, len, flags, _error);
+#elif defined MSG_NOSIGNAL
+	return dns_send(fd, src, len, (flags|MSG_NOSIGNAL), _error);
+#elif _POSIX_REALTIME_SIGNALS > 0 /* require sigtimedwait */
+	/*
+	 * SIGPIPE handling similar to the approach described in
+	 * http://krokisplace.blogspot.com/2010/02/suppressing-sigpipe-in-library.html
+	 */
+	sigset_t pending, blocked, piped;
+	size_t count;
+	int error;
+
+	sigemptyset(&pending);
+	sigpending(&pending);
+
+	if (!sigismember(&pending, SIGPIPE)) {
+		sigemptyset(&piped);
+		sigaddset(&piped, SIGPIPE);
+		sigemptyset(&blocked);
+
+		if ((error = dns_sigmask(SIG_BLOCK, &piped, &blocked)))
+			goto error;
+	}
+
+	count = dns_send(fd, src, len, flags, &error);
+
+	if (!sigismember(&pending, SIGPIPE)) {
+		int saved = error;
+
+		if (!count && error == EPIPE) {
+			while (-1 == sigtimedwait(&piped, NULL, &(struct timespec){ 0, 0 }) && errno == EINTR)
+				;;
+		}
+
+		if ((error = dns_sigmask(SIG_SETMASK, &blocked, NULL)))
+			goto error;
+
+		error = saved;
+	}
+
+	*_error = error;
+	return count;
+error:
+	*_error = error;
+	return 0;
+#else
+#error "unable to suppress SIGPIPE"
+	return dns_send(fd, src, len, flags, _error);
+#endif
+} /* dns_send_nopipe() */
+
+
+static dns_error_t dns_connect(int fd, const struct sockaddr *addr, socklen_t addrlen) {
+	if (0 != connect(fd, addr, addrlen))
+		return dns_soerr();
+	return 0;
+} /* dns_connect() */
+
+
+#define DNS_FOPEN_STDFLAGS "rwabt+"
+
+static dns_error_t dns_fopen_addflag(char *dst, const char *src, size_t lim, int fc) {
+	char *p = dst, *pe = dst + lim;
+
+	/* copy standard flags */
+	while (*src && strchr(DNS_FOPEN_STDFLAGS, *src)) {
+		if (!(p < pe))
+			return ENOMEM;
+		*p++ = *src++;
+	}
+
+	/* append flag to standard flags */
+	if (!(p < pe))
+		return ENOMEM;
+	*p++ = fc;
+
+	/* copy remaining mode string, including '\0' */
+	do {
+		if (!(p < pe))
+			return ENOMEM;
+	} while ((*p++ = *src++));
+
+	return 0;
+} /* dns_fopen_addflag() */
+
+static FILE *dns_fopen(const char *path, const char *mode, dns_error_t *_error) {
+	FILE *fp;
+	char mode_cloexec[32];
+	int error;
+
+	assert(path && mode && *mode);
+	if (!*path) {
+		error = EINVAL;
+		goto error;
+	}
+
+#if _WIN32 || _WIN64
+	if ((error = dns_fopen_addflag(mode_cloexec, mode, sizeof mode_cloexec, 'N')))
+		goto error;
+	if (!(fp = fopen(path, mode_cloexec)))
+		goto syerr;
+#else
+	if ((error = dns_fopen_addflag(mode_cloexec, mode, sizeof mode_cloexec, 'e')))
+		goto error;
+	if (!(fp = fopen(path, mode_cloexec))) {
+		if (errno != EINVAL)
+			goto syerr;
+		if (!(fp = fopen(path, mode)))
+			goto syerr;
+	}
+#endif
+
+	return fp;
+syerr:
+	error = dns_syerr();
+error:
+	*_error = error;
+
+	return NULL;
+} /* dns_fopen() */
+
+
+struct dns_hxd_lines_i {
+	int pc;
+	size_t p;
+};
+
+#define DNS_SM_RESTORE \
+	do { \
+		pc = state->pc; \
+		sp = src + state->p; \
+		se = src + len; \
+	} while (0)
+#define DNS_SM_SAVE \
+	do { \
+		state->p = sp - src; \
+		state->pc = pc; \
+	} while (0)
+
+static size_t dns_hxd_lines(void *dst, size_t lim, const unsigned char *src, size_t len, struct dns_hxd_lines_i *state) {
+	static const unsigned char hex[] = "0123456789abcdef";
+	static const unsigned char tmpl[] = "                                                    |                |\n";
+	unsigned char ln[sizeof tmpl];
+	const unsigned char *sp, *se;
+	unsigned char *h, *g;
+	unsigned i, n;
+	int pc;
+
+	DNS_SM_ENTER;
+
+	while (sp < se) {
+		memcpy(ln, tmpl, sizeof ln);
+
+		h = &ln[2];
+		g = &ln[53];
+
+		for (n = 0; n < 2; n++) {
+			for (i = 0; i < 8 && se - sp > 0; i++, sp++) {
+				h[0] = hex[0x0f & (*sp >> 4)];
+				h[1] = hex[0x0f & (*sp >> 0)];
+				h += 3;
+
+				*g++ = (dns_isgraph(*sp))? *sp : '.';
+			}
+
+			h++;
+		}
+
+		n = dns_strlcpy(dst, (char *)ln, lim);
+		DNS_SM_YIELD(n);
+	}
+
+	DNS_SM_EXIT;
+	DNS_SM_LEAVE;
+
+	return 0;
+}
+
+#undef DNS_SM_SAVE
+#undef DNS_SM_RESTORE
+
+/*
+ * A R I T H M E T I C  R O U T I N E S
+ *
+ * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
+
+#define DNS_CHECK_OVERFLOW(error, r, f, ...) \
+	do { \
+		uintmax_t _r; \
+		*(error) = f(&_r, __VA_ARGS__); \
+		*(r) = _r; \
+	} while (0)
+
+static dns_error_t dns_clamp_overflow(uintmax_t *r, uintmax_t n, uintmax_t clamp) {
+	if (n > clamp) {
+		*r = clamp;
+		return ERANGE;
+	} else {
+		*r = n;
+		return 0;
+	}
+} /* dns_clamp_overflow() */
+
+static dns_error_t dns_add_overflow(uintmax_t *r, uintmax_t a, uintmax_t b, uintmax_t clamp) {
+	if (~a < b) {
+		*r = DNS_PP_MIN(clamp, ~UINTMAX_C(0));
+		return ERANGE;
+	} else {
+		return dns_clamp_overflow(r, a + b, clamp);
+	}
+} /* dns_add_overflow() */
+
+static dns_error_t dns_mul_overflow(uintmax_t *r, uintmax_t a, uintmax_t b, uintmax_t clamp) {
+	if (a > 0 && UINTMAX_MAX / a < b) {
+		*r = DNS_PP_MIN(clamp, ~UINTMAX_C(0));
+		return ERANGE;
+	} else {
+		return dns_clamp_overflow(r, a * b, clamp);
+	}
+} /* dns_mul_overflow() */
+
+/*
+ * F I X E D - S I Z E D  B U F F E R  R O U T I N E S
+ *
+ * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
+
+#define DNS_B_INIT(src, n) { \
+	(unsigned char *)(src), \
+	(unsigned char *)(src), \
+	(unsigned char *)(src) + (n), \
+}
+
+#define DNS_B_FROM(src, n) DNS_B_INIT((src), (n))
+#define DNS_B_INTO(src, n) DNS_B_INIT((src), (n))
+
+struct dns_buf {
+	const unsigned char *base;
+	unsigned char *p;
+	const unsigned char *pe;
+	dns_error_t error;
+	size_t overflow;
+}; /* struct dns_buf */
+
+static inline size_t
+dns_b_tell(struct dns_buf *b)
+{
+	return b->p - b->base;
+}
+
+static inline dns_error_t
+dns_b_setoverflow(struct dns_buf *b, size_t n, dns_error_t error)
+{
+	b->overflow += n;
+	return b->error = error;
+}
+
+DNS_NOTUSED static struct dns_buf *
+dns_b_into(struct dns_buf *b, void *src, size_t n)
+{
+	*b = (struct dns_buf)DNS_B_INTO(src, n);
+
+	return b;
+}
+
+static dns_error_t
+dns_b_putc(struct dns_buf *b, unsigned char uc)
+{
+	if (!(b->p < b->pe))
+		return dns_b_setoverflow(b, 1, DNS_ENOBUFS);
+
+	*b->p++ = uc;
+
+	return 0;
+}
+
+static dns_error_t
+dns_b_pputc(struct dns_buf *b, unsigned char uc, size_t p)
+{
+	size_t pe = b->pe - b->base;
+	if (pe <= p)
+		return dns_b_setoverflow(b, p - pe + 1, DNS_ENOBUFS);
+
+	*((unsigned char *)b->base + p) = uc;
+
+	return 0;
+}
+
+static inline dns_error_t
+dns_b_put16(struct dns_buf *b, uint16_t u)
+{
+	return dns_b_putc(b, u >> 8), dns_b_putc(b, u >> 0);
+}
+
+static inline dns_error_t
+dns_b_pput16(struct dns_buf *b, uint16_t u, size_t p)
+{
+	if (dns_b_pputc(b, u >> 8, p) || dns_b_pputc(b, u >> 0, p + 1))
+		return b->error;
+
+	return 0;
+}
+
+DNS_NOTUSED static inline dns_error_t
+dns_b_put32(struct dns_buf *b, uint32_t u)
+{
+	return dns_b_putc(b, u >> 24), dns_b_putc(b, u >> 16),
+	    dns_b_putc(b, u >> 8), dns_b_putc(b, u >> 0);
+}
+
+static dns_error_t
+dns_b_put(struct dns_buf *b, const void *src, size_t len)
+{
+	size_t n = DNS_PP_MIN((size_t)(b->pe - b->p), len);
+
+	memcpy(b->p, src, n);
+	b->p += n;
+
+	if (n < len)
+		return dns_b_setoverflow(b, len - n, DNS_ENOBUFS);
+
+	return 0;
+}
+
+static dns_error_t
+dns_b_puts(struct dns_buf *b, const void *src)
+{
+	return dns_b_put(b, src, strlen(src));
+}
+
+DNS_NOTUSED static inline dns_error_t
+dns_b_fmtju(struct dns_buf *b, const uintmax_t u, const unsigned width)
+{
+	size_t digits, padding, overflow;
+	uintmax_t r;
+	unsigned char *tp, *te, tc;
+
+	digits = 0;
+	r = u;
+	do {
+		digits++;
+		r /= 10;
+	} while (r);
+
+	padding = width - DNS_PP_MIN(digits, width);
+	overflow = (digits + padding) - DNS_PP_MIN((size_t)(b->pe - b->p), (digits + padding));
+
+	while (padding--) {
+		dns_b_putc(b, '0');
+	}
+
+	digits = 0;
+	tp = b->p;
+	r = u;
+	do {
+		if (overflow < ++digits)
+			dns_b_putc(b, '0' + (r % 10));
+		r /= 10;
+	} while (r);
+
+	te = b->p;
+	while (tp < te) {
+		tc = *--te;
+		*te = *tp;
+		*tp++ = tc;
+	}
+
+	return b->error;
+}
+
+static void
+dns_b_popc(struct dns_buf *b)
+{
+	if (b->overflow && !--b->overflow)
+		b->error = 0;
+	if (b->p > b->base)
+		b->p--;
+}
+
+static inline const char *
+dns_b_tolstring(struct dns_buf *b, size_t *n)
+{
+	if (b->p < b->pe) {
+		*b->p = '\0';
+		*n = b->p - b->base;
+
+		return (const char *)b->base;
+	} else if (b->p > b->base) {
+		if (b->p[-1] != '\0') {
+			dns_b_setoverflow(b, 1, DNS_ENOBUFS);
+			b->p[-1] = '\0';
+		}
+		*n = &b->p[-1] - b->base;
+
+		return (const char *)b->base;
+	} else {
+		*n = 0;
+
+		return "";
+	}
+}
+
+static inline const char *
+dns_b_tostring(struct dns_buf *b)
+{
+	size_t n;
+	return dns_b_tolstring(b, &n);
+}
+
+static inline size_t
+dns_b_strlen(struct dns_buf *b)
+{
+	size_t n;
+	dns_b_tolstring(b, &n);
+	return n;
+}
+
+static inline size_t
+dns_b_strllen(struct dns_buf *b)
+{
+	size_t n = dns_b_strlen(b);
+	return n + b->overflow;
+}
+
+DNS_NOTUSED static const struct dns_buf *
+dns_b_from(const struct dns_buf *b, const void *src, size_t n)
+{
+	*(struct dns_buf *)b = (struct dns_buf)DNS_B_FROM(src, n);
+
+	return b;
+}
+
+static inline int
+dns_b_getc(const struct dns_buf *_b, const int eof)
+{
+	struct dns_buf *b = (struct dns_buf *)_b;
+
+	if (!(b->p < b->pe))
+		return dns_b_setoverflow(b, 1, DNS_EILLEGAL), eof;
+
+	return *b->p++;
+}
+
+static inline intmax_t
+dns_b_get16(const struct dns_buf *b, const intmax_t eof)
+{
+	intmax_t n;
+
+	n = (dns_b_getc(b, 0) << 8);
+	n |= (dns_b_getc(b, 0) << 0);
+
+	return (!b->overflow)? n : eof;
+}
+
+DNS_NOTUSED static inline intmax_t
+dns_b_get32(const struct dns_buf *b, const intmax_t eof)
+{
+	intmax_t n;
+
+	n = (dns_b_get16(b, 0) << 16);
+	n |= (dns_b_get16(b, 0) << 0);
+
+	return (!b->overflow)? n : eof;
+}
+
+static inline dns_error_t
+dns_b_move(struct dns_buf *dst, const struct dns_buf *_src, size_t n)
+{
+	struct dns_buf *src = (struct dns_buf *)_src;
+	size_t src_n = DNS_PP_MIN((size_t)(src->pe - src->p), n);
+	size_t src_r = n - src_n;
+
+	dns_b_put(dst, src->p, src_n);
+	src->p += src_n;
+
+	if (src_r)
+		return dns_b_setoverflow(src, src_r, DNS_EILLEGAL);
+
+	return dst->error;
+}
+
+/*
+ * T I M E  R O U T I N E S
+ *
+ * Most functions still rely on the older time routines defined in the
+ * utility routines section, above.
+ *
+ * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
+
+#define DNS_TIME_C(n) UINT64_C(n)
+#define DNS_TIME_INF (~DNS_TIME_C(0))
+
+typedef uint64_t dns_time_t;
+typedef dns_time_t dns_microseconds_t;
+
+static dns_error_t dns_time_add(dns_time_t *r, dns_time_t a, dns_time_t b) {
+	int error;
+	DNS_CHECK_OVERFLOW(&error, r, dns_add_overflow, a, b, DNS_TIME_INF);
+	return error;
+}
+
+static dns_error_t dns_time_mul(dns_time_t *r, dns_time_t a, dns_time_t b) {
+	int error;
+	DNS_CHECK_OVERFLOW(&error, r, dns_mul_overflow, a, b, DNS_TIME_INF);
+	return error;
+}
+
+static dns_error_t dns_time_diff(dns_time_t *r, dns_time_t a, dns_time_t b) {
+	if (a < b) {
+		*r = DNS_TIME_C(0);
+		return ERANGE;
+	} else {
+		*r = a - b;
+		return 0;
+	}
+}
+
+static dns_microseconds_t dns_ts2us(const struct timespec *ts, _Bool rup) {
+	if (ts) {
+		dns_time_t sec = DNS_PP_MAX(0, ts->tv_sec);
+		dns_time_t nsec = DNS_PP_MAX(0, ts->tv_nsec);
+		dns_time_t usec = nsec / 1000;
+		dns_microseconds_t r;
+
+		if (rup && nsec % 1000 > 0)
+			usec++;
+		dns_time_mul(&r, sec, DNS_TIME_C(1000000));
+		dns_time_add(&r, r, usec);
+
+		return r;
+	} else {
+		return DNS_TIME_INF;
+	}
+} /* dns_ts2us() */
+
+static struct timespec *dns_tv2ts(struct timespec *ts, const struct timeval *tv) {
+	if (tv) {
+		ts->tv_sec = tv->tv_sec;
+		ts->tv_nsec = tv->tv_usec * 1000;
+
+		return ts;
+	} else {
+		return NULL;
+	}
+} /* dns_tv2ts() */
+
+static size_t dns_utime_print(void *_dst, size_t lim, dns_microseconds_t us) {
+	struct dns_buf dst = DNS_B_INTO(_dst, lim);
+
+	dns_b_fmtju(&dst, us / 1000000, 1);
+	dns_b_putc(&dst, '.');
+	dns_b_fmtju(&dst, us % 1000000, 6);
+
+	return dns_b_strllen(&dst);
+} /* dns_utime_print() */
+
+/*
+ * P A C K E T  R O U T I N E S
+ *
+ * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
+
+unsigned dns_p_count(struct dns_packet *P, enum dns_section section) {
+	unsigned count;
+
+	switch (section) {
+	case DNS_S_QD:
+		return ntohs(dns_header(P)->qdcount);
+	case DNS_S_AN:
+		return ntohs(dns_header(P)->ancount);
+	case DNS_S_NS:
+		return ntohs(dns_header(P)->nscount);
+	case DNS_S_AR:
+		return ntohs(dns_header(P)->arcount);
+	default:
+		count = 0;
+
+		if (section & DNS_S_QD)
+			count += ntohs(dns_header(P)->qdcount);
+		if (section & DNS_S_AN)
+			count += ntohs(dns_header(P)->ancount);
+		if (section & DNS_S_NS)
+			count += ntohs(dns_header(P)->nscount);
+		if (section & DNS_S_AR)
+			count += ntohs(dns_header(P)->arcount);
+
+		return count;
+	}
+} /* dns_p_count() */
+
+
+struct dns_packet *dns_p_init(struct dns_packet *P, size_t size) {
+	if (!P)
+		return 0;
+
+	assert(size >= offsetof(struct dns_packet, data) + 12);
+
+	memset(P, 0, sizeof *P);
+	P->size = size - offsetof(struct dns_packet, data);
+	P->end  = 12;
+
+	memset(P->data, '\0', 12);
+
+	return P;
+} /* dns_p_init() */
+
+
+static struct dns_packet *dns_p_reset(struct dns_packet *P) {
+	return dns_p_init(P, offsetof(struct dns_packet, data) + P->size);
+} /* dns_p_reset() */
+
+
+static unsigned short dns_p_qend(struct dns_packet *P) {
+	unsigned short qend	= 12;
+	unsigned i, count	= dns_p_count(P, DNS_S_QD);
+
+	for (i = 0; i < count && qend < P->end; i++) {
+		if (P->end == (qend = dns_d_skip(qend, P)))
+			goto invalid;
+
+		if (P->end - qend < 4)
+			goto invalid;
+
+		qend	+= 4;
+	}
+
+	return DNS_PP_MIN(qend, P->end);
+invalid:
+	return P->end;
+} /* dns_p_qend() */
+
+
+struct dns_packet *dns_p_make(size_t len, int *error) {
+	struct dns_packet *P;
+	size_t size = dns_p_calcsize(len);
+
+	if (!(P = dns_p_init(malloc(size), size)))
+		*error = dns_syerr();
+
+	return P;
+} /* dns_p_make() */
+
+
+static void dns_p_free(struct dns_packet *P) {
+	free(P);
+} /* dns_p_free() */
+
+
+/* convience routine to free any existing packet before storing new packet */
+static struct dns_packet *dns_p_setptr(struct dns_packet **dst, struct dns_packet *src) {
+	dns_p_free(*dst);
+
+	*dst = src;
+
+	return src;
+} /* dns_p_setptr() */
+
+
+static struct dns_packet *dns_p_movptr(struct dns_packet **dst, struct dns_packet **src) {
+	dns_p_setptr(dst, *src);
+
+	*src = NULL;
+
+	return *dst;
+} /* dns_p_movptr() */
+
+
+int dns_p_grow(struct dns_packet **P) {
+	struct dns_packet *tmp;
+	size_t size;
+	int error;
+
+	if (!*P) {
+		if (!(*P = dns_p_make(DNS_P_QBUFSIZ, &error)))
+			return error;
+
+		return 0;
+	}
+
+	size = dns_p_sizeof(*P);
+	size |= size >> 1;
+	size |= size >> 2;
+	size |= size >> 4;
+	size |= size >> 8;
+	size++;
+
+	if (size > 65536)
+		return DNS_ENOBUFS;
+
+	if (!(tmp = realloc(*P, dns_p_calcsize(size))))
+		return dns_syerr();
+
+	tmp->size = size;
+	*P = tmp;
+
+	return 0;
+} /* dns_p_grow() */
+
+
+struct dns_packet *dns_p_copy(struct dns_packet *P, const struct dns_packet *P0) {
+	if (!P)
+		return 0;
+
+	P->end	= DNS_PP_MIN(P->size, P0->end);
+
+	memcpy(P->data, P0->data, P->end);
+
+	return P;
+} /* dns_p_copy() */
+
+
+struct dns_packet *dns_p_merge(struct dns_packet *A, enum dns_section Amask, struct dns_packet *B, enum dns_section Bmask, int *error_) {
+	size_t bufsiz = DNS_PP_MIN(65535, ((A)? A->end : 0) + ((B)? B->end : 0));
+	struct dns_packet *M;
+	enum dns_section section;
+	struct dns_rr rr, mr;
+	int error, copy;
+
+	if (!A && B) {
+		A = B;
+		Amask = Bmask;
+		B = 0;
+	}
+
+merge:
+	if (!(M = dns_p_make(bufsiz, &error)))
+		goto error;
+
+	for (section = DNS_S_QD; (DNS_S_ALL & section); section <<= 1) {
+		if (A && (section & Amask)) {
+			dns_rr_foreach(&rr, A, .section = section) {
+				if ((error = dns_rr_copy(M, &rr, A)))
+					goto error;
+			}
+		}
+
+		if (B && (section & Bmask)) {
+			dns_rr_foreach(&rr, B, .section = section) {
+				copy = 1;
+
+				dns_rr_foreach(&mr, M, .type = rr.type, .section = DNS_S_ALL) {
+					if (!(copy = dns_rr_cmp(&rr, B, &mr, M)))
+						break;
+				}
+
+				if (copy && (error = dns_rr_copy(M, &rr, B)))
+					goto error;
+			}
+		}
+	}
+
+	return M;
+error:
+	dns_p_setptr(&M, NULL);
+
+	if (error == DNS_ENOBUFS && bufsiz < 65535) {
+		bufsiz = DNS_PP_MIN(65535, bufsiz * 2);
+
+		goto merge;
+	}
+
+	*error_	= error;
+
+	return 0;
+} /* dns_p_merge() */
+
+
+static unsigned short dns_l_skip(unsigned short, const unsigned char *, size_t);
+
+void dns_p_dictadd(struct dns_packet *P, unsigned short dn) {
+	unsigned short lp, lptr, i;
+
+	lp	= dn;
+
+	while (lp < P->end) {
+		if (0xc0 == (0xc0 & P->data[lp]) && P->end - lp >= 2 && lp != dn) {
+			lptr	= ((0x3f & P->data[lp + 0]) << 8)
+				| ((0xff & P->data[lp + 1]) << 0);
+
+			for (i = 0; i < lengthof(P->dict) && P->dict[i]; i++) {
+				if (P->dict[i] == lptr) {
+					P->dict[i]	= dn;
+
+					return;
+				}
+			}
+		}
+
+		lp	= dns_l_skip(lp, P->data, P->end);
+	}
+
+	for (i = 0; i < lengthof(P->dict); i++) {
+		if (!P->dict[i]) {
+			P->dict[i]	= dn;
+
+			break;
+		}
+	}
+} /* dns_p_dictadd() */
+
+
+int dns_p_push(struct dns_packet *P, enum dns_section section, const void *dn, size_t dnlen, enum dns_type type, enum dns_class class, unsigned ttl, const void *any) {
+	size_t end = P->end;
+	int error;
+
+	if ((error = dns_d_push(P, dn, dnlen)))
+		goto error;
+
+	if (P->size - P->end < 4)
+		goto nobufs;
+
+	P->data[P->end++] = 0xff & (type >> 8);
+	P->data[P->end++] = 0xff & (type >> 0);
+
+	P->data[P->end++] = 0xff & (class >> 8);
+	P->data[P->end++] = 0xff & (class >> 0);
+
+	if (section == DNS_S_QD)
+		goto update;
+
+	if (P->size - P->end < 6)
+		goto nobufs;
+
+	if (type != DNS_T_OPT)
+		ttl = DNS_PP_MIN(ttl, 0x7fffffffU);
+	P->data[P->end++] = ttl >> 24;
+	P->data[P->end++] = ttl >> 16;
+	P->data[P->end++] = ttl >> 8;
+	P->data[P->end++] = ttl >> 0;
+
+	if ((error = dns_any_push(P, (union dns_any *)any, type)))
+		goto error;
+
+update:
+	switch (section) {
+	case DNS_S_QD:
+		if (dns_p_count(P, DNS_S_AN|DNS_S_NS|DNS_S_AR))
+			goto order;
+
+		if (!P->memo.qd.base && (error = dns_p_study(P)))
+			goto error;
+
+		dns_header(P)->qdcount = htons(ntohs(dns_header(P)->qdcount) + 1);
+
+		P->memo.qd.end  = P->end;
+		P->memo.an.base = P->end;
+		P->memo.an.end  = P->end;
+		P->memo.ns.base = P->end;
+		P->memo.ns.end  = P->end;
+		P->memo.ar.base = P->end;
+		P->memo.ar.end  = P->end;
+
+		break;
+	case DNS_S_AN:
+		if (dns_p_count(P, DNS_S_NS|DNS_S_AR))
+			goto order;
+
+		if (!P->memo.an.base && (error = dns_p_study(P)))
+			goto error;
+
+		dns_header(P)->ancount = htons(ntohs(dns_header(P)->ancount) + 1);
+
+		P->memo.an.end  = P->end;
+		P->memo.ns.base = P->end;
+		P->memo.ns.end  = P->end;
+		P->memo.ar.base = P->end;
+		P->memo.ar.end  = P->end;
+
+		break;
+	case DNS_S_NS:
+		if (dns_p_count(P, DNS_S_AR))
+			goto order;
+
+		if (!P->memo.ns.base && (error = dns_p_study(P)))
+			goto error;
+
+		dns_header(P)->nscount = htons(ntohs(dns_header(P)->nscount) + 1);
+
+		P->memo.ns.end  = P->end;
+		P->memo.ar.base = P->end;
+		P->memo.ar.end  = P->end;
+
+		break;
+	case DNS_S_AR:
+		if (!P->memo.ar.base && (error = dns_p_study(P)))
+			goto error;
+
+		dns_header(P)->arcount = htons(ntohs(dns_header(P)->arcount) + 1);
+
+		P->memo.ar.end = P->end;
+
+		if (type == DNS_T_OPT && !P->memo.opt.p) {
+			P->memo.opt.p = end;
+			P->memo.opt.maxudp = class;
+			P->memo.opt.ttl = ttl;
+		}
+
+		break;
+	default:
+		error = DNS_ESECTION;
+
+		goto error;
+	} /* switch() */
+
+	return 0;
+nobufs:
+	error = DNS_ENOBUFS;
+
+	goto error;
+order:
+	error = DNS_EORDER;
+
+	goto error;
+error:
+	P->end = end;
+
+	return error;
+} /* dns_p_push() */
+
+#define DNS_SM_RESTORE do { pc = state->pc; error = state->error; } while (0)
+#define DNS_SM_SAVE do { state->error = error; state->pc = pc; } while (0)
+
+struct dns_p_lines_i {
+	int pc;
+	enum dns_section section;
+	struct dns_rr rr;
+	int error;
+};
+
+static size_t dns_p_lines_fmt(void *dst, size_t lim, dns_error_t *_error, const char *fmt, ...) {
+	va_list ap;
+	int error = 0, n;
+
+	va_start(ap, fmt);
+	if ((n = vsnprintf(dst, lim, fmt, ap)) < 0)
+		error = errno;
+	va_end(ap);
+
+	*_error = error;
+	return DNS_PP_MAX(n, 0);
+} /* dns_p_lines_fmt() */
+
+#define DNS_P_LINE(...) \
+	do { \
+		len = dns_p_lines_fmt(dst, lim, &error, __VA_ARGS__); \
+		if (len == 0 && error) \
+			goto error; \
+		DNS_SM_YIELD(len); \
+	} while (0)
+
+static size_t dns_p_lines(void *dst, size_t lim, dns_error_t *_error, struct dns_packet *P, struct dns_rr_i *I, struct dns_p_lines_i *state) {
+	int error, pc;
+	size_t len;
+
+	*_error = 0;
+
+	DNS_SM_ENTER;
+
+	DNS_P_LINE(";; [HEADER]\n");
+	DNS_P_LINE(";;    qid : %d\n", ntohs(dns_header(P)->qid));
+	DNS_P_LINE(";;     qr : %s(%d)\n", (dns_header(P)->qr)? "RESPONSE" : "QUERY", dns_header(P)->qr);
+	DNS_P_LINE(";; opcode : %s(%d)\n", dns_stropcode(dns_header(P)->opcode), dns_header(P)->opcode);
+	DNS_P_LINE(";;     aa : %s(%d)\n", (dns_header(P)->aa)? "AUTHORITATIVE" : "NON-AUTHORITATIVE", dns_header(P)->aa);
+	DNS_P_LINE(";;     tc : %s(%d)\n", (dns_header(P)->tc)? "TRUNCATED" : "NOT-TRUNCATED", dns_header(P)->tc);
+	DNS_P_LINE(";;     rd : %s(%d)\n", (dns_header(P)->rd)? "RECURSION-DESIRED" : "RECURSION-NOT-DESIRED", dns_header(P)->rd);
+	DNS_P_LINE(";;     ra : %s(%d)\n", (dns_header(P)->ra)? "RECURSION-ALLOWED" : "RECURSION-NOT-ALLOWED", dns_header(P)->ra);
+	DNS_P_LINE(";;  rcode : %s(%d)\n", dns_strrcode(dns_p_rcode(P)), dns_p_rcode(P));
+
+	while (dns_rr_grep(&state->rr, 1, I, P, &error)) {
+		if (state->section != state->rr.section) {
+			DNS_P_LINE("\n");
+			DNS_P_LINE(";; [%s:%d]\n", dns_strsection(state->rr.section), dns_p_count(P, state->rr.section));
+		}
+
+		if (!(len = dns_rr_print(dst, lim, &state->rr, P, &error)))
+			goto error;
+		dns_strlcat(dst, "\n", lim);
+		DNS_SM_YIELD(len + 1);
+
+		state->section = state->rr.section;
+	}
+
+	if (error)
+		goto error;
+
+	DNS_SM_EXIT;
+error:
+	for (;;) {
+		*_error = error;
+		DNS_SM_YIELD(0);
+	}
+
+	DNS_SM_LEAVE;
+
+	*_error = 0;
+	return 0;
+} /* dns_p_lines() */
+
+#undef DNS_P_LINE
+#undef DNS_SM_SAVE
+#undef DNS_SM_RESTORE
+
+static void dns_p_dump3(struct dns_packet *P, struct dns_rr_i *I, FILE *fp) {
+	struct dns_p_lines_i lines = { 0 };
+	char line[sizeof (union dns_any) * 2];
+	size_t len;
+	int error;
+
+	while ((len = dns_p_lines(line, sizeof line, &error, P, I, &lines))) {
+		if (len < sizeof line) {
+			fwrite(line, 1, len, fp);
+		} else {
+			fwrite(line, 1, sizeof line - 1, fp);
+			fputc('\n', fp);
+		}
+	}
+} /* dns_p_dump3() */
+
+
+void dns_p_dump(struct dns_packet *P, FILE *fp) {
+	dns_p_dump3(P, dns_rr_i_new(P, .section = 0), fp);
+} /* dns_p_dump() */
+
+
+static void dns_s_unstudy(struct dns_s_memo *m)
+	{ m->base = 0; m->end = 0; }
+
+static void dns_m_unstudy(struct dns_p_memo *m) {
+	dns_s_unstudy(&m->qd);
+	dns_s_unstudy(&m->an);
+	dns_s_unstudy(&m->ns);
+	dns_s_unstudy(&m->ar);
+	m->opt.p = 0;
+	m->opt.maxudp = 0;
+	m->opt.ttl = 0;
+} /* dns_m_unstudy() */
+
+static int dns_s_study(struct dns_s_memo *m, enum dns_section section, unsigned short base, struct dns_packet *P) {
+	unsigned short count, rp;
+
+	count = dns_p_count(P, section);
+
+	for (rp = base; count && rp < P->end; count--)
+		rp = dns_rr_skip(rp, P);
+
+	m->base = base;
+	m->end  = rp;
+
+	return 0;
+} /* dns_s_study() */
+
+static int dns_m_study(struct dns_p_memo *m, struct dns_packet *P) {
+	struct dns_rr rr;
+	int error;
+
+	if ((error = dns_s_study(&m->qd, DNS_S_QD, 12, P)))
+		goto error;
+	if ((error = dns_s_study(&m->an, DNS_S_AN, m->qd.end, P)))
+		goto error;
+	if ((error = dns_s_study(&m->ns, DNS_S_NS, m->an.end, P)))
+		goto error;
+	if ((error = dns_s_study(&m->ar, DNS_S_AR, m->ns.end, P)))
+		goto error;
+
+	m->opt.p = 0;
+	m->opt.maxudp = 0;
+	m->opt.ttl = 0;
+	dns_rr_foreach(&rr, P, .type = DNS_T_OPT, .section = DNS_S_AR) {
+		m->opt.p = rr.dn.p;
+		m->opt.maxudp = rr.class;
+		m->opt.ttl = rr.ttl;
+		break;
+	}
+
+	return 0;
+error:
+	dns_m_unstudy(m);
+
+	return error;
+} /* dns_m_study() */
+
+int dns_p_study(struct dns_packet *P) {
+	return dns_m_study(&P->memo, P);
+} /* dns_p_study() */
+
+
+enum dns_rcode dns_p_rcode(struct dns_packet *P) {
+	return 0xfff & ((P->memo.opt.ttl >> 20) | dns_header(P)->rcode);
+} /* dns_p_rcode() */
+
+
+/*
+ * Q U E R Y  P A C K E T  R O U T I N E S
+ *
+ * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
+
+#define DNS_Q_RD    0x1 /* recursion desired */
+#define DNS_Q_EDNS0 0x2 /* include OPT RR */
+
+static dns_error_t
+dns_q_make2(struct dns_packet **_Q, const char *qname, size_t qlen, enum dns_type qtype, enum dns_class qclass, int qflags)
+{
+	struct dns_packet *Q = NULL;
+	int error;
+
+	if (dns_p_movptr(&Q, _Q)) {
+		dns_p_reset(Q);
+	} else if (!(Q = dns_p_make(DNS_P_QBUFSIZ, &error))) {
+		goto error;
+	}
+
+	if ((error = dns_p_push(Q, DNS_S_QD, qname, qlen, qtype, qclass, 0, 0)))
+		goto error;
+
+	dns_header(Q)->rd = !!(qflags & DNS_Q_RD);
+
+	if (qflags & DNS_Q_EDNS0) {
+		struct dns_opt opt = DNS_OPT_INIT(&opt);
+
+		opt.version = 0; /* RFC 6891 version */
+		opt.maxudp = 4096;
+
+		if ((error = dns_p_push(Q, DNS_S_AR, ".", 1, DNS_T_OPT, dns_opt_class(&opt), dns_opt_ttl(&opt), &opt)))
+			goto error;
+	}
+
+	*_Q = Q;
+
+	return 0;
+error:
+	dns_p_free(Q);
+
+	return error;
+}
+
+static dns_error_t
+dns_q_make(struct dns_packet **Q, const char *qname, enum dns_type qtype, enum dns_class qclass, int qflags)
+{
+	return dns_q_make2(Q, qname, strlen(qname), qtype, qclass, qflags);
+}
+
+static dns_error_t
+dns_q_remake(struct dns_packet **Q, int qflags)
+{
+	char qname[DNS_D_MAXNAME + 1];
+	size_t qlen;
+	struct dns_rr rr;
+	int error;
+
+	assert(Q && *Q);
+	if ((error = dns_rr_parse(&rr, 12, *Q)))
+		return error;
+	if (!(qlen = dns_d_expand(qname, sizeof qname, rr.dn.p, *Q, &error)))
+		return error;
+	if (qlen >= sizeof qname)
+		return DNS_EILLEGAL;
+	return dns_q_make2(Q, qname, qlen, rr.type, rr.class, qflags);
+}
+
+/*
+ * D O M A I N  N A M E  R O U T I N E S
+ *
+ * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
+
+#ifndef DNS_D_MAXPTRS
+#define DNS_D_MAXPTRS	127	/* Arbitrary; possible, valid depth is something like packet size / 2 + fudge. */
+#endif
+
+static size_t dns_l_expand(unsigned char *dst, size_t lim, unsigned short src, unsigned short *nxt, const unsigned char *data, size_t end) {
+	unsigned short len;
+	unsigned nptrs	= 0;
+
+retry:
+	if (src >= end)
+		goto invalid;
+
+	switch (0x03 & (data[src] >> 6)) {
+	case 0x00:
+		len	= (0x3f & (data[src++]));
+
+		if (end - src < len)
+			goto invalid;
+
+		if (lim > 0) {
+			memcpy(dst, &data[src], DNS_PP_MIN(lim, len));
+
+			dst[DNS_PP_MIN(lim - 1, len)]	= '\0';
+		}
+
+		*nxt	= src + len;
+
+		return len;
+	case 0x01:
+		goto invalid;
+	case 0x02:
+		goto invalid;
+	case 0x03:
+		if (++nptrs > DNS_D_MAXPTRS)
+			goto invalid;
+
+		if (end - src < 2)
+			goto invalid;
+
+		src	= ((0x3f & data[src + 0]) << 8)
+			| ((0xff & data[src + 1]) << 0);
+
+		goto retry;
+	} /* switch() */
+
+	/* NOT REACHED */
+invalid:
+	*nxt	= end;
+
+	return 0;
+} /* dns_l_expand() */
+
+
+static unsigned short dns_l_skip(unsigned short src, const unsigned char *data, size_t end) {
+	unsigned short len;
+
+	if (src >= end)
+		goto invalid;
+
+	switch (0x03 & (data[src] >> 6)) {
+	case 0x00:
+		len	= (0x3f & (data[src++]));
+
+		if (end - src < len)
+			goto invalid;
+
+		return (len)? src + len : end;
+	case 0x01:
+		goto invalid;
+	case 0x02:
+		goto invalid;
+	case 0x03:
+		return end;
+	} /* switch() */
+
+	/* NOT REACHED */
+invalid:
+	return end;
+} /* dns_l_skip() */
+
+
+static _Bool dns_d_isanchored(const void *_src, size_t len) {
+	const unsigned char *src = _src;
+	return len > 0 && src[len - 1] == '.';
+} /* dns_d_isanchored() */
+
+
+static size_t dns_d_ndots(const void *_src, size_t len) {
+	const unsigned char *p = _src, *pe = p + len;
+	size_t ndots = 0;
+
+	while ((p = memchr(p, '.', pe - p))) {
+		ndots++;
+		p++;
+	}
+
+	return ndots;
+} /* dns_d_ndots() */
+
+
+static size_t dns_d_trim(void *dst_, size_t lim, const void *src_, size_t len, int flags) {
+	unsigned char *dst = dst_;
+	const unsigned char *src = src_;
+	size_t dp = 0, sp = 0;
+	int lc;
+
+	/* trim any leading dot(s) */
+	while (sp < len && src[sp] == '.')
+		sp++;
+
+	for (lc = 0; sp < len; lc = src[sp++]) {
+		/* trim extra dot(s) */
+		if (src[sp] == '.' && lc == '.')
+			continue;
+
+		if (dp < lim)
+			dst[dp] = src[sp];
+
+		dp++;
+	}
+
+	if ((flags & DNS_D_ANCHOR) && lc != '.') {
+		if (dp < lim)
+			dst[dp] = '.';
+
+		dp++;
+	}
+
+	if (lim > 0)
+		dst[DNS_PP_MIN(dp, lim - 1)] = '\0';
+
+	return dp;
+} /* dns_d_trim() */
+
+
+char *dns_d_init(void *dst, size_t lim, const void *src, size_t len, int flags) {
+	if (flags & DNS_D_TRIM) {
+		dns_d_trim(dst, lim, src, len, flags);
+	} if (flags & DNS_D_ANCHOR) {
+		dns_d_anchor(dst, lim, src, len);
+	} else {
+		memmove(dst, src, DNS_PP_MIN(lim, len));
+
+		if (lim > 0)
+			((char *)dst)[DNS_PP_MIN(len, lim - 1)]	= '\0';
+	}
+
+	return dst;
+} /* dns_d_init() */
+
+
+size_t dns_d_anchor(void *dst, size_t lim, const void *src, size_t len) {
+	if (len == 0)
+		return 0;
+
+	memmove(dst, src, DNS_PP_MIN(lim, len));
+
+	if (((const char *)src)[len - 1] != '.') {
+		if (len < lim)
+			((char *)dst)[len]	= '.';
+		len++;
+	}
+
+	if (lim > 0)
+		((char *)dst)[DNS_PP_MIN(lim - 1, len)]	= '\0';
+
+	return len;
+} /* dns_d_anchor() */
+
+
+size_t dns_d_cleave(void *dst, size_t lim, const void *src, size_t len) {
+	const char *dot;
+
+	/* XXX: Skip any leading dot. Handles cleaving root ".". */
+	if (len == 0 || !(dot = memchr((const char *)src + 1, '.', len - 1)))
+		return 0;
+
+	len	-= dot - (const char *)src;
+
+	/* XXX: Unless root, skip the label's trailing dot. */
+	if (len > 1) {
+		src	= ++dot;
+		len--;
+	} else
+		src	= dot;
+
+	memmove(dst, src, DNS_PP_MIN(lim, len));
+
+	if (lim > 0)
+		((char *)dst)[DNS_PP_MIN(lim - 1, len)]	= '\0';
+
+	return len;
+} /* dns_d_cleave() */
+
+
+size_t dns_d_comp(void *dst_, size_t lim, const void *src_, size_t len, struct dns_packet *P, int *error) {
+	struct { unsigned char *b; size_t p, x; } dst, src;
+	unsigned char ch	= '.';
+
+	dst.b	= dst_;
+	dst.p	= 0;
+	dst.x	= 1;
+
+	src.b	= (unsigned char *)src_;
+	src.p	= 0;
+	src.x	= 0;
+
+	while (src.x < len) {
+		ch	= src.b[src.x];
+
+		if (ch == '.') {
+			if (dst.p < lim)
+				dst.b[dst.p]	= (0x3f & (src.x - src.p));
+
+			dst.p	= dst.x++;
+			src.p	= ++src.x;
+		} else {
+			if (dst.x < lim)
+				dst.b[dst.x]	= ch;
+
+			dst.x++;
+			src.x++;
+		}
+	} /* while() */
+
+	if (src.x > src.p) {
+		if (dst.p < lim)
+			dst.b[dst.p]	= (0x3f & (src.x - src.p));
+
+		dst.p	= dst.x;
+	}
+
+	if (dst.p > 1) {
+		if (dst.p < lim)
+			dst.b[dst.p]	= 0x00;
+
+		dst.p++;
+	}
+
+#if 1
+	if (dst.p < lim) {
+		struct { unsigned char label[DNS_D_MAXLABEL + 1]; size_t len; unsigned short p, x, y; } a, b;
+		unsigned i;
+
+		a.p	= 0;
+
+		while ((a.len = dns_l_expand(a.label, sizeof a.label, a.p, &a.x, dst.b, lim))) {
+			for (i = 0; i < lengthof(P->dict) && P->dict[i]; i++) {
+				b.p	= P->dict[i];
+
+				while ((b.len = dns_l_expand(b.label, sizeof b.label, b.p, &b.x, P->data, P->end))) {
+					a.y	= a.x;
+					b.y	= b.x;
+
+					while (a.len && b.len && 0 == strcasecmp((char *)a.label, (char *)b.label)) {
+						a.len = dns_l_expand(a.label, sizeof a.label, a.y, &a.y, dst.b, lim);
+						b.len = dns_l_expand(b.label, sizeof b.label, b.y, &b.y, P->data, P->end);
+					}
+
+					if (a.len == 0 && b.len == 0 && b.p <= 0x3fff) {
+						dst.b[a.p++]	= 0xc0
+								| (0x3f & (b.p >> 8));
+						dst.b[a.p++]	= (0xff & (b.p >> 0));
+
+						/* silence static analyzers */
+						dns_assume(a.p > 0);
+
+						return a.p;
+					}
+
+					b.p	= b.x;
+				} /* while() */
+			} /* for() */
+
+			a.p	= a.x;
+		} /* while() */
+	} /* if () */
+#endif
+
+	if (!dst.p)
+		*error = DNS_EILLEGAL;
+
+	return dst.p;
+} /* dns_d_comp() */
+
+
+unsigned short dns_d_skip(unsigned short src, struct dns_packet *P) {
+	unsigned short len;
+
+	while (src < P->end) {
+		switch (0x03 & (P->data[src] >> 6)) {
+		case 0x00:	/* FOLLOWS */
+			len	= (0x3f & P->data[src++]);
+
+			if (0 == len) {
+/* success ==> */		return src;
+			} else if (P->end - src > len) {
+				src	+= len;
+
+				break;
+			} else
+				goto invalid;
+
+			/* NOT REACHED */
+		case 0x01:	/* RESERVED */
+			goto invalid;
+		case 0x02:	/* RESERVED */
+			goto invalid;
+		case 0x03:	/* POINTER */
+			if (P->end - src < 2)
+				goto invalid;
+
+			src	+= 2;
+
+/* success ==> */	return src;
+		} /* switch() */
+	} /* while() */
+
+invalid:
+	return P->end;
+} /* dns_d_skip() */
+
+
+#include <stdio.h>
+
+size_t dns_d_expand(void *dst, size_t lim, unsigned short src, struct dns_packet *P, int *error) {
+	size_t dstp	= 0;
+	unsigned nptrs	= 0;
+	unsigned char len;
+
+	while (src < P->end) {
+		switch ((0x03 & (P->data[src] >> 6))) {
+		case 0x00:	/* FOLLOWS */
+			len	= (0x3f & P->data[src]);
+
+			if (0 == len) {
+				if (dstp == 0) {
+					if (dstp < lim)
+						((unsigned char *)dst)[dstp]	= '.';
+
+					dstp++;
+				}
+
+				/* NUL terminate */
+				if (lim > 0)
+					((unsigned char *)dst)[DNS_PP_MIN(dstp, lim - 1)]	= '\0';
+
+/* success ==> */		return dstp;
+			}
+
+			src++;
+
+			if (P->end - src < len)
+				goto toolong;
+
+			if (dstp < lim)
+				memcpy(&((unsigned char *)dst)[dstp], &P->data[src], DNS_PP_MIN(len, lim - dstp));
+
+			src	+= len;
+			dstp	+= len;
+
+			if (dstp < lim)
+				((unsigned char *)dst)[dstp]	= '.';
+
+			dstp++;
+
+			nptrs	= 0;
+
+			continue;
+		case 0x01:	/* RESERVED */
+			goto reserved;
+		case 0x02:	/* RESERVED */
+			goto reserved;
+		case 0x03:	/* POINTER */
+			if (++nptrs > DNS_D_MAXPTRS)
+				goto toolong;
+
+			if (P->end - src < 2)
+				goto toolong;
+
+			src	= ((0x3f & P->data[src + 0]) << 8)
+				| ((0xff & P->data[src + 1]) << 0);
+
+			continue;
+		} /* switch() */
+	} /* while() */
+
+toolong:
+	*error	= DNS_EILLEGAL;
+
+	if (lim > 0)
+		((unsigned char *)dst)[DNS_PP_MIN(dstp, lim - 1)]	= '\0';
+
+	return 0;
+reserved:
+	*error	= DNS_EILLEGAL;
+
+	if (lim > 0)
+		((unsigned char *)dst)[DNS_PP_MIN(dstp, lim - 1)]	= '\0';
+
+	return 0;
+} /* dns_d_expand() */
+
+
+int dns_d_push(struct dns_packet *P, const void *dn, size_t len) {
+	size_t lim	= P->size - P->end;
+	unsigned dp	= P->end;
+	int error	= DNS_EILLEGAL; /* silence compiler */
+
+	len	= dns_d_comp(&P->data[dp], lim, dn, len, P, &error);
+
+	if (len == 0)
+		return error;
+	if (len > lim)
+		return DNS_ENOBUFS;
+
+	P->end	+= len;
+
+	dns_p_dictadd(P, dp);
+
+	return 0;
+} /* dns_d_push() */
+
+
+size_t dns_d_cname(void *dst, size_t lim, const void *dn, size_t len, struct dns_packet *P, int *error_) {
+	char host[DNS_D_MAXNAME + 1];
+	struct dns_rr_i i;
+	struct dns_rr rr;
+	unsigned depth;
+	int error;
+
+	if (sizeof host <= dns_d_anchor(host, sizeof host, dn, len))
+		{ error = ENAMETOOLONG; goto error; }
+
+	for (depth = 0; depth < 7; depth++) {
+		dns_rr_i_init(memset(&i, 0, sizeof i), P);
+
+		i.section	= DNS_S_ALL & ~DNS_S_QD;
+		i.name		= host;
+		i.type		= DNS_T_CNAME;
+
+		if (!dns_rr_grep(&rr, 1, &i, P, &error))
+			break;
+
+		if ((error = dns_cname_parse((struct dns_cname *)host, &rr, P)))
+			goto error;
+	}
+
+	return dns_strlcpy(dst, host, lim);
+error:
+	*error_	= error;
+
+	return 0;
+} /* dns_d_cname() */
+
+
+/*
+ * R E S O U R C E  R E C O R D  R O U T I N E S
+ *
+ * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
+
+int dns_rr_copy(struct dns_packet *P, struct dns_rr *rr, struct dns_packet *Q) {
+	unsigned char dn[DNS_D_MAXNAME + 1];
+	union dns_any any;
+	size_t len;
+	int error;
+
+	if (!(len = dns_d_expand(dn, sizeof dn, rr->dn.p, Q, &error)))
+		return error;
+	else if (len >= sizeof dn)
+		return DNS_EILLEGAL;
+
+	if (rr->section != DNS_S_QD && (error = dns_any_parse(dns_any_init(&any, sizeof any), rr, Q)))
+		return error;
+
+	return dns_p_push(P, rr->section, dn, len, rr->type, rr->class, rr->ttl, &any);
+} /* dns_rr_copy() */
+
+
+int dns_rr_parse(struct dns_rr *rr, unsigned short src, struct dns_packet *P) {
+	unsigned short p	= src;
+
+	if (src >= P->end)
+		goto invalid;
+
+	rr->dn.p   = p;
+	rr->dn.len = (p = dns_d_skip(p, P)) - rr->dn.p;
+
+	if (P->end - p < 4)
+		goto invalid;
+
+	rr->type = ((0xff & P->data[p + 0]) << 8)
+	         | ((0xff & P->data[p + 1]) << 0);
+
+	rr->class = ((0xff & P->data[p + 2]) << 8)
+	          | ((0xff & P->data[p + 3]) << 0);
+
+	p += 4;
+
+	if (src < dns_p_qend(P)) {
+		rr->section = DNS_S_QUESTION;
+
+		rr->ttl    = 0;
+		rr->rd.p   = 0;
+		rr->rd.len = 0;
+
+		return 0;
+	}
+
+	if (P->end - p < 4)
+		goto invalid;
+
+	rr->ttl = ((0xff & P->data[p + 0]) << 24)
+	        | ((0xff & P->data[p + 1]) << 16)
+	        | ((0xff & P->data[p + 2]) << 8)
+	        | ((0xff & P->data[p + 3]) << 0);
+	if (rr->type != DNS_T_OPT)
+		rr->ttl = DNS_PP_MIN(rr->ttl, 0x7fffffffU);
+
+	p += 4;
+
+	if (P->end - p < 2)
+		goto invalid;
+
+	rr->rd.len = ((0xff & P->data[p + 0]) << 8)
+	           | ((0xff & P->data[p + 1]) << 0);
+	rr->rd.p = p + 2;
+
+	p += 2;
+
+	if (P->end - p < rr->rd.len)
+		goto invalid;
+
+	return 0;
+invalid:
+	return DNS_EILLEGAL;
+} /* dns_rr_parse() */
+
+
+static unsigned short dns_rr_len(const unsigned short src, struct dns_packet *P) {
+	unsigned short rp, rdlen;
+
+	rp	= dns_d_skip(src, P);
+
+	if (P->end - rp < 4)
+		return P->end - src;
+
+	rp	+= 4;	/* TYPE, CLASS */
+
+	if (rp <= dns_p_qend(P))
+		return rp - src;
+
+	if (P->end - rp < 6)
+		return P->end - src;
+
+	rp	+= 6;	/* TTL, RDLEN */
+
+	rdlen	= ((0xff & P->data[rp - 2]) << 8)
+		| ((0xff & P->data[rp - 1]) << 0);
+
+	if (P->end - rp < rdlen)
+		return P->end - src;
+
+	rp	+= rdlen;
+
+	return rp - src;
+} /* dns_rr_len() */
+
+
+unsigned short dns_rr_skip(unsigned short src, struct dns_packet *P) {
+	return src + dns_rr_len(src, P);
+} /* dns_rr_skip() */
+
+
+static enum dns_section dns_rr_section(unsigned short src, struct dns_packet *P) {
+	enum dns_section section;
+	unsigned count, index;
+	unsigned short rp;
+
+	if (src >= P->memo.qd.base && src < P->memo.qd.end)
+		return DNS_S_QD;
+	if (src >= P->memo.an.base && src < P->memo.an.end)
+		return DNS_S_AN;
+	if (src >= P->memo.ns.base && src < P->memo.ns.end)
+		return DNS_S_NS;
+	if (src >= P->memo.ar.base && src < P->memo.ar.end)
+		return DNS_S_AR;
+
+	/* NOTE: Possibly bad memoization. Try it the hard-way. */
+
+	for (rp = 12, index = 0; rp < src && rp < P->end; index++)
+		rp = dns_rr_skip(rp, P);
+
+	section = DNS_S_QD;
+	count   = dns_p_count(P, section);
+
+	while (index >= count && section <= DNS_S_AR) {
+		section <<= 1;
+		count += dns_p_count(P, section);
+	}
+
+	return DNS_S_ALL & section;
+} /* dns_rr_section() */
+
+
+static enum dns_type dns_rr_type(unsigned short src, struct dns_packet *P) {
+	struct dns_rr rr;
+	int error;
+
+	if ((error = dns_rr_parse(&rr, src, P)))
+		return 0;
+
+	return rr.type;
+} /* dns_rr_type() */
+
+
+int dns_rr_cmp(struct dns_rr *r0, struct dns_packet *P0, struct dns_rr *r1, struct dns_packet *P1) {
+	char host0[DNS_D_MAXNAME + 1], host1[DNS_D_MAXNAME + 1];
+	union dns_any any0, any1;
+	int cmp, error;
+	size_t len;
+
+	if ((cmp = r0->type - r1->type))
+		return cmp;
+
+	if ((cmp = r0->class - r1->class))
+		return cmp;
+
+	/*
+	 * FIXME: Do label-by-label comparison to handle illegally long names?
+	 */
+
+	if (!(len = dns_d_expand(host0, sizeof host0, r0->dn.p, P0, &error))
+	||  len >= sizeof host0)
+		return -1;
+
+	if (!(len = dns_d_expand(host1, sizeof host1, r1->dn.p, P1, &error))
+	||  len >= sizeof host1)
+		return 1;
+
+	if ((cmp = strcasecmp(host0, host1)))
+		return cmp;
+
+	if (DNS_S_QD & (r0->section | r1->section)) {
+		if (r0->section == r1->section)
+			return 0;
+
+		return (r0->section == DNS_S_QD)? -1 : 1;
+	}
+
+	if ((error = dns_any_parse(&any0, r0, P0)))
+		return -1;
+
+	if ((error = dns_any_parse(&any1, r1, P1)))
+		return 1;
+
+	return dns_any_cmp(&any0, r0->type, &any1, r1->type);
+} /* dns_rr_cmp() */
+
+
+static _Bool dns_rr_exists(struct dns_rr *rr0, struct dns_packet *P0, struct dns_packet *P1) {
+	struct dns_rr rr1;
+
+	dns_rr_foreach(&rr1, P1, .section = rr0->section, .type = rr0->type) {
+		if (0 == dns_rr_cmp(rr0, P0, &rr1, P1))
+			return 1;
+	}
+
+	return 0;
+} /* dns_rr_exists() */
+
+
+static unsigned short dns_rr_offset(struct dns_rr *rr) {
+	return rr->dn.p;
+} /* dns_rr_offset() */
+
+
+static _Bool dns_rr_i_match(struct dns_rr *rr, struct dns_rr_i *i, struct dns_packet *P) {
+	if (i->section && !(rr->section & i->section))
+		return 0;
+
+	if (i->type && rr->type != i->type && i->type != DNS_T_ALL)
+		return 0;
+
+	if (i->class && rr->class != i->class && i->class != DNS_C_ANY)
+		return 0;
+
+	if (i->name) {
+		char dn[DNS_D_MAXNAME + 1];
+		size_t len;
+		int error;
+
+		if (!(len = dns_d_expand(dn, sizeof dn, rr->dn.p, P, &error))
+		||  len >= sizeof dn)
+			return 0;
+
+		if (0 != strcasecmp(dn, i->name))
+			return 0;
+	}
+
+	if (i->data && i->type && rr->section > DNS_S_QD) {
+		union dns_any rd;
+		int error;
+
+		if ((error = dns_any_parse(&rd, rr, P)))
+			return 0;
+
+		if (0 != dns_any_cmp(&rd, rr->type, i->data, i->type))
+			return 0;
+	}
+
+	return 1;
+} /* dns_rr_i_match() */
+
+
+static unsigned short dns_rr_i_start(struct dns_rr_i *i, struct dns_packet *P) {
+	unsigned short rp;
+	struct dns_rr r0, rr;
+	int error;
+
+	if ((i->section & DNS_S_QD) && P->memo.qd.base)
+		rp = P->memo.qd.base;
+	else if ((i->section & DNS_S_AN) && P->memo.an.base)
+		rp = P->memo.an.base;
+	else if ((i->section & DNS_S_NS) && P->memo.ns.base)
+		rp = P->memo.ns.base;
+	else if ((i->section & DNS_S_AR) && P->memo.ar.base)
+		rp = P->memo.ar.base;
+	else
+		rp = 12;
+
+	for (; rp < P->end; rp = dns_rr_skip(rp, P)) {
+		if ((error = dns_rr_parse(&rr, rp, P)))
+			continue;
+
+		rr.section = dns_rr_section(rp, P);
+
+		if (!dns_rr_i_match(&rr, i, P))
+			continue;
+
+		r0 = rr;
+
+		goto lower;
+	}
+
+	return P->end;
+lower:
+	if (i->sort == &dns_rr_i_packet)
+		return dns_rr_offset(&r0);
+
+	while ((rp = dns_rr_skip(rp, P)) < P->end) {
+		if ((error = dns_rr_parse(&rr, rp, P)))
+			continue;
+
+		rr.section = dns_rr_section(rp, P);
+
+		if (!dns_rr_i_match(&rr, i, P))
+			continue;
+
+		if (i->sort(&rr, &r0, i, P) < 0)
+			r0 = rr;
+	}
+
+	return dns_rr_offset(&r0);
+} /* dns_rr_i_start() */
+
+
+static unsigned short dns_rr_i_skip(unsigned short rp, struct dns_rr_i *i, struct dns_packet *P) {
+	struct dns_rr r0, r1, rr;
+	int error;
+
+	if ((error = dns_rr_parse(&r0, rp, P)))
+		return P->end;
+
+	r0.section = dns_rr_section(rp, P);
+
+	rp = (i->sort == &dns_rr_i_packet)? dns_rr_skip(rp, P) : 12;
+
+	for (; rp < P->end; rp = dns_rr_skip(rp, P)) {
+		if ((error = dns_rr_parse(&rr, rp, P)))
+			continue;
+
+		rr.section = dns_rr_section(rp, P);
+
+		if (!dns_rr_i_match(&rr, i, P))
+			continue;
+
+		if (i->sort(&rr, &r0, i, P) <= 0)
+			continue;
+
+		r1 = rr;
+
+		goto lower;
+	}
+
+	return P->end;
+lower:
+	if (i->sort == &dns_rr_i_packet)
+		return dns_rr_offset(&r1);
+
+	while ((rp = dns_rr_skip(rp, P)) < P->end) {
+		if ((error = dns_rr_parse(&rr, rp, P)))
+			continue;
+
+		rr.section = dns_rr_section(rp, P);
+
+		if (!dns_rr_i_match(&rr, i, P))
+			continue;
+
+		if (i->sort(&rr, &r0, i, P) <= 0)
+			continue;
+
+		if (i->sort(&rr, &r1, i, P) >= 0)
+			continue;
+
+		r1 = rr;
+	}
+
+	return dns_rr_offset(&r1);
+} /* dns_rr_i_skip() */
+
+
+int dns_rr_i_packet(struct dns_rr *a, struct dns_rr *b, struct dns_rr_i *i, struct dns_packet *P) {
+	(void)i;
+	(void)P;
+
+	return (int)a->dn.p - (int)b->dn.p;
+} /* dns_rr_i_packet() */
+
+
+int dns_rr_i_order(struct dns_rr *a, struct dns_rr *b, struct dns_rr_i *i, struct dns_packet *P) {
+	int cmp;
+
+	(void)i;
+
+	if ((cmp = a->section - b->section))
+		return cmp;
+
+	if (a->type != b->type)
+		return (int)a->dn.p - (int)b->dn.p;
+
+	return dns_rr_cmp(a, P, b, P);
+} /* dns_rr_i_order() */
+
+
+int dns_rr_i_shuffle(struct dns_rr *a, struct dns_rr *b, struct dns_rr_i *i, struct dns_packet *P) {
+	int cmp;
+
+	(void)i;
+	(void)P;
+
+	while (!i->state.regs[0])
+		i->state.regs[0]	= dns_random();
+
+	if ((cmp = a->section - b->section))
+		return cmp;
+
+	return dns_k_shuffle16(a->dn.p, i->state.regs[0]) - dns_k_shuffle16(b->dn.p, i->state.regs[0]);
+} /* dns_rr_i_shuffle() */
+
+
+struct dns_rr_i *dns_rr_i_init(struct dns_rr_i *i, struct dns_packet *P) {
+	static const struct dns_rr_i i_initializer;
+
+	(void)P;
+
+	i->state	= i_initializer.state;
+	i->saved	= i->state;
+
+	return i;
+} /* dns_rr_i_init() */
+
+
+unsigned dns_rr_grep(struct dns_rr *rr, unsigned lim, struct dns_rr_i *i, struct dns_packet *P, int *error_) {
+	unsigned count	= 0;
+	int error;
+
+	switch (i->state.exec) {
+	case 0:
+		if (!i->sort)
+			i->sort	= &dns_rr_i_packet;
+
+		i->state.next	= dns_rr_i_start(i, P);
+		i->state.exec++;
+
+		/* FALL THROUGH */
+	case 1:
+		while (count < lim && i->state.next < P->end) {
+			if ((error = dns_rr_parse(rr, i->state.next, P)))
+				goto error;
+
+			rr->section	= dns_rr_section(i->state.next, P);
+
+			rr++;
+			count++;
+			i->state.count++;
+
+			i->state.next	= dns_rr_i_skip(i->state.next, i, P);
+		} /* while() */
+
+		break;
+	} /* switch() */
+
+	return count;
+error:
+	*error_	= error;
+
+	return count;
+} /* dns_rr_grep() */
+
+
+size_t dns_rr_print(void *_dst, size_t lim, struct dns_rr *rr, struct dns_packet *P, int *_error) {
+	struct dns_buf dst = DNS_B_INTO(_dst, lim);
+	union dns_any any;
+	size_t n;
+	int error;
+
+	if (rr->section == DNS_S_QD)
+		dns_b_putc(&dst, ';');
+
+	if (!(n = dns_d_expand(any.ns.host, sizeof any.ns.host, rr->dn.p, P, &error)))
+		goto error;
+	dns_b_put(&dst, any.ns.host, DNS_PP_MIN(n, sizeof any.ns.host - 1));
+
+	if (rr->section != DNS_S_QD) {
+		dns_b_putc(&dst, ' ');
+		dns_b_fmtju(&dst, rr->ttl, 0);
+	}
+
+	dns_b_putc(&dst, ' ');
+	dns_b_puts(&dst, dns_strclass(rr->class));
+	dns_b_putc(&dst, ' ');
+	dns_b_puts(&dst, dns_strtype(rr->type));
+
+	if (rr->section == DNS_S_QD)
+		goto epilog;
+
+	dns_b_putc(&dst, ' ');
+
+	if ((error = dns_any_parse(dns_any_init(&any, sizeof any), rr, P)))
+		goto error;
+
+	n = dns_any_print(dst.p, dst.pe - dst.p, &any, rr->type);
+	dst.p += DNS_PP_MIN(n, (size_t)(dst.pe - dst.p));
+epilog:
+	return dns_b_strllen(&dst);
+error:
+	*_error = error;
+
+	return 0;
+} /* dns_rr_print() */
+
+
+int dns_a_parse(struct dns_a *a, struct dns_rr *rr, struct dns_packet *P) {
+	unsigned long addr;
+
+	if (rr->rd.len != 4)
+		return DNS_EILLEGAL;
+
+	addr	= ((0xffU & P->data[rr->rd.p + 0]) << 24)
+		| ((0xffU & P->data[rr->rd.p + 1]) << 16)
+		| ((0xffU & P->data[rr->rd.p + 2]) << 8)
+		| ((0xffU & P->data[rr->rd.p + 3]) << 0);
+
+	a->addr.s_addr	= htonl(addr);
+
+	return 0;
+} /* dns_a_parse() */
+
+
+int dns_a_push(struct dns_packet *P, struct dns_a *a) {
+	unsigned long addr;
+
+	if (P->size - P->end < 6)
+		return DNS_ENOBUFS;
+
+	P->data[P->end++]	= 0x00;
+	P->data[P->end++]	= 0x04;
+
+	addr	= ntohl(a->addr.s_addr);
+
+	P->data[P->end++]	= 0xffU & (addr >> 24);
+	P->data[P->end++]	= 0xffU & (addr >> 16);
+	P->data[P->end++]	= 0xffU & (addr >> 8);
+	P->data[P->end++]	= 0xffU & (addr >> 0);
+
+	return 0;
+} /* dns_a_push() */
+
+
+size_t dns_a_arpa(void *_dst, size_t lim, const struct dns_a *a) {
+	struct dns_buf dst = DNS_B_INTO(_dst, lim);
+	unsigned long octets = ntohl(a->addr.s_addr);
+	unsigned i;
+
+	for (i = 0; i < 4; i++) {
+		dns_b_fmtju(&dst, 0xff & octets, 0);
+		dns_b_putc(&dst, '.');
+		octets >>= 8;
+	}
+
+	dns_b_puts(&dst, "in-addr.arpa.");
+
+	return dns_b_strllen(&dst);
+} /* dns_a_arpa() */
+
+
+int dns_a_cmp(const struct dns_a *a, const struct dns_a *b) {
+	if (ntohl(a->addr.s_addr) < ntohl(b->addr.s_addr))
+		return -1;
+	if (ntohl(a->addr.s_addr) > ntohl(b->addr.s_addr))
+		return 1;
+
+	return 0;
+} /* dns_a_cmp() */
+
+
+size_t dns_a_print(void *dst, size_t lim, struct dns_a *a) {
+	char addr[INET_ADDRSTRLEN + 1]	= "0.0.0.0";
+
+	dns_inet_ntop(AF_INET, &a->addr, addr, sizeof addr);
+
+	return dns_strlcpy(dst, addr, lim);
+} /* dns_a_print() */
+
+
+int dns_aaaa_parse(struct dns_aaaa *aaaa, struct dns_rr *rr, struct dns_packet *P) {
+	if (rr->rd.len != sizeof aaaa->addr.s6_addr)
+		return DNS_EILLEGAL;
+
+	memcpy(aaaa->addr.s6_addr, &P->data[rr->rd.p], sizeof aaaa->addr.s6_addr);
+
+	return 0;
+} /* dns_aaaa_parse() */
+
+
+int dns_aaaa_push(struct dns_packet *P, struct dns_aaaa *aaaa) {
+	if (P->size - P->end < 2 + sizeof aaaa->addr.s6_addr)
+		return DNS_ENOBUFS;
+
+	P->data[P->end++]	= 0x00;
+	P->data[P->end++]	= 0x10;
+
+	memcpy(&P->data[P->end], aaaa->addr.s6_addr, sizeof aaaa->addr.s6_addr);
+
+	P->end	+= sizeof aaaa->addr.s6_addr;
+
+	return 0;
+} /* dns_aaaa_push() */
+
+
+int dns_aaaa_cmp(const struct dns_aaaa *a, const struct dns_aaaa *b) {
+	unsigned i;
+	int cmp;
+
+	for (i = 0; i < lengthof(a->addr.s6_addr); i++) {
+		if ((cmp = (a->addr.s6_addr[i] - b->addr.s6_addr[i])))
+			return cmp;
+	}
+
+	return 0;
+} /* dns_aaaa_cmp() */
+
+
+size_t dns_aaaa_arpa(void *_dst, size_t lim, const struct dns_aaaa *aaaa) {
+	static const unsigned char hex[16] = "0123456789abcdef";
+	struct dns_buf dst = DNS_B_INTO(_dst, lim);
+	unsigned nyble;
+	int i, j;
+
+	for (i = sizeof aaaa->addr.s6_addr - 1; i >= 0; i--) {
+		nyble = aaaa->addr.s6_addr[i];
+
+		for (j = 0; j < 2; j++) {
+			dns_b_putc(&dst, hex[0x0f & nyble]);
+			dns_b_putc(&dst, '.');
+			nyble >>= 4;
+		}
+	}
+
+	dns_b_puts(&dst, "ip6.arpa.");
+
+	return dns_b_strllen(&dst);
+} /* dns_aaaa_arpa() */
+
+
+size_t dns_aaaa_print(void *dst, size_t lim, struct dns_aaaa *aaaa) {
+	char addr[INET6_ADDRSTRLEN + 1]	= "::";
+
+	dns_inet_ntop(AF_INET6, &aaaa->addr, addr, sizeof addr);
+
+	return dns_strlcpy(dst, addr, lim);
+} /* dns_aaaa_print() */
+
+
+int dns_mx_parse(struct dns_mx *mx, struct dns_rr *rr, struct dns_packet *P) {
+	size_t len;
+	int error;
+
+	if (rr->rd.len < 3)
+		return DNS_EILLEGAL;
+
+	mx->preference	= (0xff00 & (P->data[rr->rd.p + 0] << 8))
+			| (0x00ff & (P->data[rr->rd.p + 1] << 0));
+
+	if (!(len = dns_d_expand(mx->host, sizeof mx->host, rr->rd.p + 2, P, &error)))
+		return error;
+	else if (len >= sizeof mx->host)
+		return DNS_EILLEGAL;
+
+	return 0;
+} /* dns_mx_parse() */
+
+
+int dns_mx_push(struct dns_packet *P, struct dns_mx *mx) {
+	size_t end, len;
+	int error;
+
+	if (P->size - P->end < 5)
+		return DNS_ENOBUFS;
+
+	end	= P->end;
+	P->end	+= 2;
+
+	P->data[P->end++]	= 0xff & (mx->preference >> 8);
+	P->data[P->end++]	= 0xff & (mx->preference >> 0);
+
+	if ((error = dns_d_push(P, mx->host, strlen(mx->host))))
+		goto error;
+
+	len	= P->end - end - 2;
+
+	P->data[end + 0]	= 0xff & (len >> 8);
+	P->data[end + 1]	= 0xff & (len >> 0);
+
+	return 0;
+error:
+	P->end	= end;
+
+	return error;
+} /* dns_mx_push() */
+
+
+int dns_mx_cmp(const struct dns_mx *a, const struct dns_mx *b) {
+	int cmp;
+
+	if ((cmp = a->preference - b->preference))
+		return cmp;
+
+	return strcasecmp(a->host, b->host);
+} /* dns_mx_cmp() */
+
+
+size_t dns_mx_print(void *_dst, size_t lim, struct dns_mx *mx) {
+	struct dns_buf dst = DNS_B_INTO(_dst, lim);
+
+	dns_b_fmtju(&dst, mx->preference, 0);
+	dns_b_putc(&dst, ' ');
+	dns_b_puts(&dst, mx->host);
+
+	return dns_b_strllen(&dst);
+} /* dns_mx_print() */
+
+
+size_t dns_mx_cname(void *dst, size_t lim, struct dns_mx *mx) {
+	return dns_strlcpy(dst, mx->host, lim);
+} /* dns_mx_cname() */
+
+
+int dns_ns_parse(struct dns_ns *ns, struct dns_rr *rr, struct dns_packet *P) {
+	size_t len;
+	int error;
+
+	if (!(len = dns_d_expand(ns->host, sizeof ns->host, rr->rd.p, P, &error)))
+		return error;
+	else if (len >= sizeof ns->host)
+		return DNS_EILLEGAL;
+
+	return 0;
+} /* dns_ns_parse() */
+
+
+int dns_ns_push(struct dns_packet *P, struct dns_ns *ns) {
+	size_t end, len;
+	int error;
+
+	if (P->size - P->end < 3)
+		return DNS_ENOBUFS;
+
+	end	= P->end;
+	P->end	+= 2;
+
+	if ((error = dns_d_push(P, ns->host, strlen(ns->host))))
+		goto error;
+
+	len	= P->end - end - 2;
+
+	P->data[end + 0]	= 0xff & (len >> 8);
+	P->data[end + 1]	= 0xff & (len >> 0);
+
+	return 0;
+error:
+	P->end	= end;
+
+	return error;
+} /* dns_ns_push() */
+
+
+int dns_ns_cmp(const struct dns_ns *a, const struct dns_ns *b) {
+	return strcasecmp(a->host, b->host);
+} /* dns_ns_cmp() */
+
+
+size_t dns_ns_print(void *dst, size_t lim, struct dns_ns *ns) {
+	return dns_strlcpy(dst, ns->host, lim);
+} /* dns_ns_print() */
+
+
+size_t dns_ns_cname(void *dst, size_t lim, struct dns_ns *ns) {
+	return dns_strlcpy(dst, ns->host, lim);
+} /* dns_ns_cname() */
+
+
+int dns_cname_parse(struct dns_cname *cname, struct dns_rr *rr, struct dns_packet *P) {
+	return dns_ns_parse((struct dns_ns *)cname, rr, P);
+} /* dns_cname_parse() */
+
+
+int dns_cname_push(struct dns_packet *P, struct dns_cname *cname) {
+	return dns_ns_push(P, (struct dns_ns *)cname);
+} /* dns_cname_push() */
+
+
+int dns_cname_cmp(const struct dns_cname *a, const struct dns_cname *b) {
+	return strcasecmp(a->host, b->host);
+} /* dns_cname_cmp() */
+
+
+size_t dns_cname_print(void *dst, size_t lim, struct dns_cname *cname) {
+	return dns_ns_print(dst, lim, (struct dns_ns *)cname);
+} /* dns_cname_print() */
+
+
+size_t dns_cname_cname(void *dst, size_t lim, struct dns_cname *cname) {
+	return dns_strlcpy(dst, cname->host, lim);
+} /* dns_cname_cname() */
+
+
+int dns_soa_parse(struct dns_soa *soa, struct dns_rr *rr, struct dns_packet *P) {
+	struct { void *dst; size_t lim; } dn[] =
+		{ { soa->mname, sizeof soa->mname },
+		  { soa->rname, sizeof soa->rname } };
+	unsigned *ts[] =
+		{ &soa->serial, &soa->refresh, &soa->retry, &soa->expire, &soa->minimum };
+	unsigned short rp;
+	unsigned i, j, n;
+	int error;
+
+	/* MNAME / RNAME */
+	if ((rp = rr->rd.p) >= P->end)
+		return DNS_EILLEGAL;
+
+	for (i = 0; i < lengthof(dn); i++) {
+		if (!(n = dns_d_expand(dn[i].dst, dn[i].lim, rp, P, &error)))
+			return error;
+		else if (n >= dn[i].lim)
+			return DNS_EILLEGAL;
+
+		if ((rp = dns_d_skip(rp, P)) >= P->end)
+			return DNS_EILLEGAL;
+	}
+
+	/* SERIAL / REFRESH / RETRY / EXPIRE / MINIMUM */
+	for (i = 0; i < lengthof(ts); i++) {
+		for (j = 0; j < 4; j++, rp++) {
+			if (rp >= P->end)
+				return DNS_EILLEGAL;
+
+			*ts[i]	<<= 8;
+			*ts[i]	|= (0xff & P->data[rp]);
+		}
+	}
+
+	return 0;
+} /* dns_soa_parse() */
+
+
+int dns_soa_push(struct dns_packet *P, struct dns_soa *soa) {
+	void *dn[]	= { soa->mname, soa->rname };
+	unsigned ts[]	= { (0xffffffff & soa->serial),
+			    (0x7fffffff & soa->refresh),
+			    (0x7fffffff & soa->retry),
+			    (0x7fffffff & soa->expire),
+			    (0xffffffff & soa->minimum) };
+	unsigned i, j;
+	size_t end, len;
+	int error;
+
+	end	= P->end;
+
+	if ((P->end += 2) >= P->size)
+		goto toolong;
+
+	/* MNAME / RNAME */
+	for (i = 0; i < lengthof(dn); i++) {
+		if ((error = dns_d_push(P, dn[i], strlen(dn[i]))))
+			goto error;
+	}
+
+	/* SERIAL / REFRESH / RETRY / EXPIRE / MINIMUM */
+	for (i = 0; i < lengthof(ts); i++) {
+		if ((P->end += 4) >= P->size)
+			goto toolong;
+
+		for (j = 1; j <= 4; j++) {
+			P->data[P->end - j]	= (0xff & ts[i]);
+			ts[i]			>>= 8;
+		}
+	}
+
+	len			= P->end - end - 2;
+	P->data[end + 0]	= (0xff & (len >> 8));
+	P->data[end + 1]	= (0xff & (len >> 0));
+
+	return 0;
+toolong:
+	error	= DNS_ENOBUFS;
+
+	/* FALL THROUGH */
+error:
+	P->end	= end;
+
+	return error;
+} /* dns_soa_push() */
+
+
+int dns_soa_cmp(const struct dns_soa *a, const struct dns_soa *b) {
+	int cmp;
+
+	if ((cmp = strcasecmp(a->mname, b->mname)))
+		return cmp;
+
+	if ((cmp = strcasecmp(a->rname, b->rname)))
+		return cmp;
+
+	if (a->serial > b->serial)
+		return -1;
+	else if (a->serial < b->serial)
+		return 1;
+
+	if (a->refresh > b->refresh)
+		return -1;
+	else if (a->refresh < b->refresh)
+		return 1;
+
+	if (a->retry > b->retry)
+		return -1;
+	else if (a->retry < b->retry)
+		return 1;
+
+	if (a->expire > b->expire)
+		return -1;
+	else if (a->expire < b->expire)
+		return 1;
+
+	if (a->minimum > b->minimum)
+		return -1;
+	else if (a->minimum < b->minimum)
+		return 1;
+
+	return 0;
+} /* dns_soa_cmp() */
+
+
+size_t dns_soa_print(void *_dst, size_t lim, struct dns_soa *soa) {
+	struct dns_buf dst = DNS_B_INTO(_dst, lim);
+
+	dns_b_puts(&dst, soa->mname);
+	dns_b_putc(&dst, ' ');
+	dns_b_puts(&dst, soa->rname);
+	dns_b_putc(&dst, ' ');
+	dns_b_fmtju(&dst, soa->serial, 0);
+	dns_b_putc(&dst, ' ');
+	dns_b_fmtju(&dst, soa->refresh, 0);
+	dns_b_putc(&dst, ' ');
+	dns_b_fmtju(&dst, soa->retry, 0);
+	dns_b_putc(&dst, ' ');
+	dns_b_fmtju(&dst, soa->expire, 0);
+	dns_b_putc(&dst, ' ');
+	dns_b_fmtju(&dst, soa->minimum, 0);
+
+	return dns_b_strllen(&dst);
+} /* dns_soa_print() */
+
+
+int dns_srv_parse(struct dns_srv *srv, struct dns_rr *rr, struct dns_packet *P) {
+	unsigned short rp;
+	unsigned i;
+	size_t n;
+	int error;
+
+	memset(srv, '\0', sizeof *srv);
+
+	rp	= rr->rd.p;
+
+	if (rr->rd.len < 7)
+		return DNS_EILLEGAL;
+
+	for (i = 0; i < 2; i++, rp++) {
+		srv->priority	<<= 8;
+		srv->priority	|= (0xff & P->data[rp]);
+	}
+
+	for (i = 0; i < 2; i++, rp++) {
+		srv->weight	<<= 8;
+		srv->weight	|= (0xff & P->data[rp]);
+	}
+
+	for (i = 0; i < 2; i++, rp++) {
+		srv->port	<<= 8;
+		srv->port	|= (0xff & P->data[rp]);
+	}
+
+	if (!(n = dns_d_expand(srv->target, sizeof srv->target, rp, P, &error)))
+		return error;
+	else if (n >= sizeof srv->target)
+		return DNS_EILLEGAL;
+
+	return 0;
+} /* dns_srv_parse() */
+
+
+int dns_srv_push(struct dns_packet *P, struct dns_srv *srv) {
+	size_t end, len;
+	int error;
+
+	end	= P->end;
+
+	if (P->size - P->end < 2)
+		goto toolong;
+
+	P->end	+= 2;
+
+	if (P->size - P->end < 6)
+		goto toolong;
+
+	P->data[P->end++]	= 0xff & (srv->priority >> 8);
+	P->data[P->end++]	= 0xff & (srv->priority >> 0);
+
+	P->data[P->end++]	= 0xff & (srv->weight >> 8);
+	P->data[P->end++]	= 0xff & (srv->weight >> 0);
+
+	P->data[P->end++]	= 0xff & (srv->port >> 8);
+	P->data[P->end++]	= 0xff & (srv->port >> 0);
+
+	if (0 == (len = dns_d_comp(&P->data[P->end], P->size - P->end, srv->target, strlen(srv->target), P, &error)))
+		goto error;
+	else if (P->size - P->end < len)
+		goto toolong;
+
+	P->end	+= len;
+
+	if (P->end > 65535)
+		goto toolong;
+
+	len	= P->end - end - 2;
+
+	P->data[end + 0]	= 0xff & (len >> 8);
+	P->data[end + 1]	= 0xff & (len >> 0);
+
+	return 0;
+toolong:
+	error	= DNS_ENOBUFS;
+
+	/* FALL THROUGH */
+error:
+	P->end	= end;
+
+	return error;
+} /* dns_srv_push() */
+
+
+int dns_srv_cmp(const struct dns_srv *a, const struct dns_srv *b) {
+	int cmp;
+
+	if ((cmp = a->priority - b->priority))
+		return cmp;
+
+	/*
+	 * FIXME: We need some sort of random seed to implement the dynamic
+	 * weighting required by RFC 2782.
+	 */
+	if ((cmp = a->weight - b->weight))
+		return cmp;
+
+	if ((cmp = a->port - b->port))
+		return cmp;
+
+	return strcasecmp(a->target, b->target);
+} /* dns_srv_cmp() */
+
+
+size_t dns_srv_print(void *_dst, size_t lim, struct dns_srv *srv) {
+	struct dns_buf dst = DNS_B_INTO(_dst, lim);
+
+	dns_b_fmtju(&dst, srv->priority, 0);
+	dns_b_putc(&dst, ' ');
+	dns_b_fmtju(&dst, srv->weight, 0);
+	dns_b_putc(&dst, ' ');
+	dns_b_fmtju(&dst, srv->port, 0);
+	dns_b_putc(&dst, ' ');
+	dns_b_puts(&dst, srv->target);
+
+	return dns_b_strllen(&dst);
+} /* dns_srv_print() */
+
+
+size_t dns_srv_cname(void *dst, size_t lim, struct dns_srv *srv) {
+	return dns_strlcpy(dst, srv->target, lim);
+} /* dns_srv_cname() */
+
+
+unsigned int dns_opt_ttl(const struct dns_opt *opt) {
+	unsigned int ttl = 0;
+
+	ttl |= (0xffU & opt->rcode) << 24;
+	ttl |= (0xffU & opt->version) << 16;
+	ttl |= (0xffffU & opt->flags) << 0;
+
+	return ttl;
+} /* dns_opt_ttl() */
+
+
+unsigned short dns_opt_class(const struct dns_opt *opt) {
+	return opt->maxudp;
+} /* dns_opt_class() */
+
+
+struct dns_opt *dns_opt_init(struct dns_opt *opt, size_t size) {
+	assert(size >= offsetof(struct dns_opt, data));
+
+	opt->size = size - offsetof(struct dns_opt, data);
+	opt->len  = 0;
+
+	opt->rcode   = 0;
+	opt->version = 0;
+	opt->maxudp  = 0;
+
+	return opt;
+} /* dns_opt_init() */
+
+
+static union dns_any *dns_opt_initany(union dns_any *any, size_t size) {
+	return dns_opt_init(&any->opt, size), any;
+} /* dns_opt_initany() */
+
+
+int dns_opt_parse(struct dns_opt *opt, struct dns_rr *rr, struct dns_packet *P) {
+	const struct dns_buf src = DNS_B_FROM(&P->data[rr->rd.p], rr->rd.len);
+	struct dns_buf dst = DNS_B_INTO(opt->data, opt->size);
+	int error;
+
+	opt->rcode = 0xfff & ((rr->ttl >> 20) | dns_header(P)->rcode);
+	opt->version = 0xff & (rr->ttl >> 16);
+	opt->flags = 0xffff & rr->ttl;
+	opt->maxudp = 0xffff & rr->class;
+
+	while (src.p < src.pe) {
+		int code, len;
+
+		if (-1 == (code = dns_b_get16(&src, -1)))
+			return src.error;
+		if (-1 == (len = dns_b_get16(&src, -1)))
+			return src.error;
+
+		switch (code) {
+		default:
+			dns_b_put16(&dst, code);
+			dns_b_put16(&dst, len);
+			if ((error = dns_b_move(&dst, &src, len)))
+				return error;
+			break;
+		}
+	}
+
+	return 0;
+} /* dns_opt_parse() */
+
+
+int dns_opt_push(struct dns_packet *P, struct dns_opt *opt) {
+	const struct dns_buf src = DNS_B_FROM(opt->data, opt->len);
+	struct dns_buf dst = DNS_B_INTO(&P->data[P->end], (P->size - P->end));
+	int error;
+
+	/* rdata length (see below) */
+	if ((error = dns_b_put16(&dst, 0)))
+		goto error;
+
+	/* ... push known options here */
+
+	/* push opaque option data */
+	if ((error = dns_b_move(&dst, &src, (size_t)(src.pe - src.p))))
+		goto error;
+
+	/* rdata length */
+	if ((error = dns_b_pput16(&dst, dns_b_tell(&dst) - 2, 0)))
+		goto error;
+
+#if !DNS_DEBUG_OPT_FORMERR
+	P->end += dns_b_tell(&dst);
+#endif
+
+	return 0;
+error:
+	return error;
+} /* dns_opt_push() */
+
+
+int dns_opt_cmp(const struct dns_opt *a, const struct dns_opt *b) {
+	(void)a;
+	(void)b;
+
+	return -1;
+} /* dns_opt_cmp() */
+
+
+size_t dns_opt_print(void *_dst, size_t lim, struct dns_opt *opt) {
+	struct dns_buf dst = DNS_B_INTO(_dst, lim);
+	size_t p;
+
+	dns_b_putc(&dst, '"');
+
+	for (p = 0; p < opt->len; p++) {
+		dns_b_putc(&dst, '\\');
+		dns_b_fmtju(&dst, opt->data[p], 3);
+	}
+
+	dns_b_putc(&dst, '"');
+
+	return dns_b_strllen(&dst);
+} /* dns_opt_print() */
+
+
+int dns_ptr_parse(struct dns_ptr *ptr, struct dns_rr *rr, struct dns_packet *P) {
+	return dns_ns_parse((struct dns_ns *)ptr, rr, P);
+} /* dns_ptr_parse() */
+
+
+int dns_ptr_push(struct dns_packet *P, struct dns_ptr *ptr) {
+	return dns_ns_push(P, (struct dns_ns *)ptr);
+} /* dns_ptr_push() */
+
+
+size_t dns_ptr_qname(void *dst, size_t lim, int af, void *addr) {
+	switch (af) {
+	case AF_INET6:
+		return dns_aaaa_arpa(dst, lim, addr);
+	case AF_INET:
+		return dns_a_arpa(dst, lim, addr);
+	default: {
+		struct dns_a a;
+		a.addr.s_addr = INADDR_NONE;
+		return dns_a_arpa(dst, lim, &a);
+	}
+	}
+} /* dns_ptr_qname() */
+
+
+int dns_ptr_cmp(const struct dns_ptr *a, const struct dns_ptr *b) {
+	return strcasecmp(a->host, b->host);
+} /* dns_ptr_cmp() */
+
+
+size_t dns_ptr_print(void *dst, size_t lim, struct dns_ptr *ptr) {
+	return dns_ns_print(dst, lim, (struct dns_ns *)ptr);
+} /* dns_ptr_print() */
+
+
+size_t dns_ptr_cname(void *dst, size_t lim, struct dns_ptr *ptr) {
+	return dns_strlcpy(dst, ptr->host, lim);
+} /* dns_ptr_cname() */
+
+
+int dns_sshfp_parse(struct dns_sshfp *fp, struct dns_rr *rr, struct dns_packet *P) {
+	unsigned p = rr->rd.p, pe = rr->rd.p + rr->rd.len;
+
+	if (pe - p < 2)
+		return DNS_EILLEGAL;
+
+	fp->algo = P->data[p++];
+	fp->type = P->data[p++];
+
+	switch (fp->type) {
+	case DNS_SSHFP_SHA1:
+		if (pe - p < sizeof fp->digest.sha1)
+			return DNS_EILLEGAL;
+
+		memcpy(fp->digest.sha1, &P->data[p], sizeof fp->digest.sha1);
+
+		break;
+	default:
+		break;
+	} /* switch() */
+
+	return 0;
+} /* dns_sshfp_parse() */
+
+
+int dns_sshfp_push(struct dns_packet *P, struct dns_sshfp *fp) {
+	unsigned p = P->end, pe = P->size, n;
+
+	if (pe - p < 4)
+		return DNS_ENOBUFS;
+
+	p += 2;
+	P->data[p++] = 0xff & fp->algo;
+	P->data[p++] = 0xff & fp->type;
+
+	switch (fp->type) {
+	case DNS_SSHFP_SHA1:
+		if (pe - p < sizeof fp->digest.sha1)
+			return DNS_ENOBUFS;
+
+		memcpy(&P->data[p], fp->digest.sha1, sizeof fp->digest.sha1);
+		p += sizeof fp->digest.sha1;
+
+		break;
+	default:
+		return DNS_EILLEGAL;
+	} /* switch() */
+
+	n = p - P->end - 2;
+	P->data[P->end++] = 0xff & (n >> 8);
+	P->data[P->end++] = 0xff & (n >> 0);
+	P->end = p;
+
+	return 0;
+} /* dns_sshfp_push() */
+
+
+int dns_sshfp_cmp(const struct dns_sshfp *a, const struct dns_sshfp *b) {
+	int cmp;
+
+	if ((cmp = a->algo - b->algo) || (cmp = a->type - b->type))
+		return cmp;
+
+	switch (a->type) {
+	case DNS_SSHFP_SHA1:
+		return memcmp(a->digest.sha1, b->digest.sha1, sizeof a->digest.sha1);
+	default:
+		return 0;
+	} /* switch() */
+
+	/* NOT REACHED */
+} /* dns_sshfp_cmp() */
+
+
+size_t dns_sshfp_print(void *_dst, size_t lim, struct dns_sshfp *fp) {
+	static const unsigned char hex[16] = "0123456789abcdef";
+	struct dns_buf dst = DNS_B_INTO(_dst, lim);
+	size_t i;
+
+	dns_b_fmtju(&dst, fp->algo, 0);
+	dns_b_putc(&dst, ' ');
+	dns_b_fmtju(&dst, fp->type, 0);
+	dns_b_putc(&dst, ' ');
+
+	switch (fp->type) {
+	case DNS_SSHFP_SHA1:
+		for (i = 0; i < sizeof fp->digest.sha1; i++) {
+			dns_b_putc(&dst, hex[0x0f & (fp->digest.sha1[i] >> 4)]);
+			dns_b_putc(&dst, hex[0x0f & (fp->digest.sha1[i] >> 0)]);
+		}
+
+		break;
+	default:
+		dns_b_putc(&dst, '0');
+
+		break;
+	} /* switch() */
+
+	return dns_b_strllen(&dst);
+} /* dns_sshfp_print() */
+
+
+struct dns_txt *dns_txt_init(struct dns_txt *txt, size_t size) {
+	assert(size > offsetof(struct dns_txt, data));
+
+	txt->size	= size - offsetof(struct dns_txt, data);
+	txt->len	= 0;
+
+	return txt;
+} /* dns_txt_init() */
+
+
+static union dns_any *dns_txt_initany(union dns_any *any, size_t size) {
+	/* NB: union dns_any is already initialized as struct dns_txt */
+	(void)size;
+	return any;
+} /* dns_txt_initany() */
+
+
+int dns_txt_parse(struct dns_txt *txt, struct dns_rr *rr, struct dns_packet *P) {
+	struct { unsigned char *b; size_t p, end; } dst, src;
+	unsigned n;
+
+	dst.b	= txt->data;
+	dst.p	= 0;
+	dst.end	= txt->size;
+
+	src.b	= P->data;
+	src.p	= rr->rd.p;
+	src.end	= src.p + rr->rd.len;
+
+	while (src.p < src.end) {
+		n	= 0xff & P->data[src.p++];
+
+		if (src.end - src.p < n || dst.end - dst.p < n)
+			return DNS_EILLEGAL;
+
+		memcpy(&dst.b[dst.p], &src.b[src.p], n);
+
+		dst.p	+= n;
+		src.p	+= n;
+	}
+
+	txt->len	= dst.p;
+
+	return 0;
+} /* dns_txt_parse() */
+
+
+int dns_txt_push(struct dns_packet *P, struct dns_txt *txt) {
+	struct { unsigned char *b; size_t p, end; } dst, src;
+	unsigned n;
+
+	dst.b	= P->data;
+	dst.p	= P->end;
+	dst.end	= P->size;
+
+	src.b	= txt->data;
+	src.p	= 0;
+	src.end	= txt->len;
+
+	if (dst.end - dst.p < 2)
+		return DNS_ENOBUFS;
+
+	n	= txt->len + ((txt->len + 254) / 255);
+
+	dst.b[dst.p++]	= 0xff & (n >> 8);
+	dst.b[dst.p++]	= 0xff & (n >> 0);
+
+	while (src.p < src.end) {
+		n	= DNS_PP_MIN(255, src.end - src.p);
+
+		if (dst.p >= dst.end)
+			return DNS_ENOBUFS;
+
+		dst.b[dst.p++]	= n;
+
+		if (dst.end - dst.p < n)
+			return DNS_ENOBUFS;
+
+		memcpy(&dst.b[dst.p], &src.b[src.p], n);
+
+		dst.p	+= n;
+		src.p	+= n;
+	}
+
+	P->end	= dst.p;
+
+	return 0;
+} /* dns_txt_push() */
+
+
+int dns_txt_cmp(const struct dns_txt *a, const struct dns_txt *b) {
+	(void)a;
+	(void)b;
+
+	return -1;
+} /* dns_txt_cmp() */
+
+
+size_t dns_txt_print(void *_dst, size_t lim, struct dns_txt *txt) {
+	struct dns_buf src = DNS_B_FROM(txt->data, txt->len);
+	struct dns_buf dst = DNS_B_INTO(_dst, lim);
+	unsigned i;
+
+	if (src.p < src.pe) {
+		do {
+			dns_b_putc(&dst, '"');
+
+			for (i = 0; i < 256 && src.p < src.pe; i++, src.p++) {
+				if (*src.p < 32 || *src.p > 126 || *src.p == '"' || *src.p == '\\') {
+					dns_b_putc(&dst, '\\');
+					dns_b_fmtju(&dst, *src.p, 3);
+				} else {
+					dns_b_putc(&dst, *src.p);
+				}
+			}
+
+			dns_b_putc(&dst, '"');
+			dns_b_putc(&dst, ' ');
+		} while (src.p < src.pe);
+
+		dns_b_popc(&dst);
+	} else {
+		dns_b_putc(&dst, '"');
+		dns_b_putc(&dst, '"');
+	}
+
+	return dns_b_strllen(&dst);
+} /* dns_txt_print() */
+
+
+static const struct dns_rrtype {
+	enum dns_type type;
+	const char *name;
+	union dns_any *(*init)(union dns_any *, size_t);
+	int (*parse)();
+	int (*push)();
+	int (*cmp)();
+	size_t (*print)();
+	size_t (*cname)();
+} dns_rrtypes[]	= {
+	{ DNS_T_A,      "A",      0,                 &dns_a_parse,      &dns_a_push,      &dns_a_cmp,      &dns_a_print,      0,                },
+	{ DNS_T_AAAA,   "AAAA",   0,                 &dns_aaaa_parse,   &dns_aaaa_push,   &dns_aaaa_cmp,   &dns_aaaa_print,   0,                },
+	{ DNS_T_MX,     "MX",     0,                 &dns_mx_parse,     &dns_mx_push,     &dns_mx_cmp,     &dns_mx_print,     &dns_mx_cname,    },
+	{ DNS_T_NS,     "NS",     0,                 &dns_ns_parse,     &dns_ns_push,     &dns_ns_cmp,     &dns_ns_print,     &dns_ns_cname,    },
+	{ DNS_T_CNAME,  "CNAME",  0,                 &dns_cname_parse,  &dns_cname_push,  &dns_cname_cmp,  &dns_cname_print,  &dns_cname_cname, },
+	{ DNS_T_SOA,    "SOA",    0,                 &dns_soa_parse,    &dns_soa_push,    &dns_soa_cmp,    &dns_soa_print,    0,                },
+	{ DNS_T_SRV,    "SRV",    0,                 &dns_srv_parse,    &dns_srv_push,    &dns_srv_cmp,    &dns_srv_print,    &dns_srv_cname,   },
+	{ DNS_T_OPT,    "OPT",    &dns_opt_initany,  &dns_opt_parse,    &dns_opt_push,    &dns_opt_cmp,    &dns_opt_print,    0,                },
+	{ DNS_T_PTR,    "PTR",    0,                 &dns_ptr_parse,    &dns_ptr_push,    &dns_ptr_cmp,    &dns_ptr_print,    &dns_ptr_cname,   },
+	{ DNS_T_TXT,    "TXT",    &dns_txt_initany,  &dns_txt_parse,    &dns_txt_push,    &dns_txt_cmp,    &dns_txt_print,    0,                },
+	{ DNS_T_SPF,    "SPF",    &dns_txt_initany,  &dns_txt_parse,    &dns_txt_push,    &dns_txt_cmp,    &dns_txt_print,    0,                },
+	{ DNS_T_SSHFP,  "SSHFP",  0,                 &dns_sshfp_parse,  &dns_sshfp_push,  &dns_sshfp_cmp,  &dns_sshfp_print,  0,                },
+	{ DNS_T_AXFR,   "AXFR",   0,                 0,                 0,                0,               0,                 0,                },
+}; /* dns_rrtypes[] */
+
+static const struct dns_rrtype *dns_rrtype(enum dns_type type) {
+	const struct dns_rrtype *t;
+
+	for (t = dns_rrtypes; t < endof(dns_rrtypes); t++) {
+		if (t->type == type && t->parse) {
+			return t;
+		}
+	}
+
+	return NULL;
+} /* dns_rrtype() */
+
+
+union dns_any *dns_any_init(union dns_any *any, size_t size) {
+	dns_static_assert(dns_same_type(any->txt, any->rdata, 1), "unexpected rdata type");
+	return (union dns_any *)dns_txt_init(&any->rdata, size);
+} /* dns_any_init() */
+
+
+static size_t dns_any_sizeof(union dns_any *any) {
+	dns_static_assert(dns_same_type(any->txt, any->rdata, 1), "unexpected rdata type");
+	return offsetof(struct dns_txt, data) + any->rdata.size;
+} /* dns_any_sizeof() */
+
+static union dns_any *dns_any_reinit(union dns_any *any, const struct dns_rrtype *t) {
+	return (t->init)? t->init(any, dns_any_sizeof(any)) : any;
+} /* dns_any_reinit() */
+
+int dns_any_parse(union dns_any *any, struct dns_rr *rr, struct dns_packet *P) {
+	const struct dns_rrtype *t;
+
+	if ((t = dns_rrtype(rr->type)))
+		return t->parse(dns_any_reinit(any, t), rr, P);
+
+	if (rr->rd.len > any->rdata.size)
+		return DNS_EILLEGAL;
+
+	memcpy(any->rdata.data, &P->data[rr->rd.p], rr->rd.len);
+	any->rdata.len	= rr->rd.len;
+
+	return 0;
+} /* dns_any_parse() */
+
+
+int dns_any_push(struct dns_packet *P, union dns_any *any, enum dns_type type) {
+	const struct dns_rrtype *t;
+
+	if ((t = dns_rrtype(type)))
+		return t->push(P, any);
+
+	if (P->size - P->end < any->rdata.len + 2)
+		return DNS_ENOBUFS;
+
+	P->data[P->end++]	= 0xff & (any->rdata.len >> 8);
+	P->data[P->end++]	= 0xff & (any->rdata.len >> 0);
+
+	memcpy(&P->data[P->end], any->rdata.data, any->rdata.len);
+	P->end	+= any->rdata.len;
+
+	return 0;
+} /* dns_any_push() */
+
+
+int dns_any_cmp(const union dns_any *a, enum dns_type x, const union dns_any *b, enum dns_type y) {
+	const struct dns_rrtype *t;
+	int cmp;
+
+	if ((cmp = x - y))
+		return cmp;
+
+	if ((t = dns_rrtype(x)))
+		return t->cmp(a, b);
+
+	return -1;
+} /* dns_any_cmp() */
+
+
+size_t dns_any_print(void *_dst, size_t lim, union dns_any *any, enum dns_type type) {
+	const struct dns_rrtype *t;
+	struct dns_buf src, dst;
+
+	if ((t = dns_rrtype(type)))
+		return t->print(_dst, lim, any);
+
+	dns_b_from(&src, any->rdata.data, any->rdata.len);
+	dns_b_into(&dst, _dst, lim);
+
+	dns_b_putc(&dst, '"');
+
+	while (src.p < src.pe) {
+		dns_b_putc(&dst, '\\');
+		dns_b_fmtju(&dst, *src.p++, 3);
+	}
+
+	dns_b_putc(&dst, '"');
+
+	return dns_b_strllen(&dst);
+} /* dns_any_print() */
+
+
+size_t dns_any_cname(void *dst, size_t lim, union dns_any *any, enum dns_type type) {
+	const struct dns_rrtype *t;
+
+	if ((t = dns_rrtype(type)) && t->cname)
+		return t->cname(dst, lim, any);
+
+	return 0;
+} /* dns_any_cname() */
+
+
+/*
+ * E V E N T  T R A C I N G  R O U T I N E S
+ *
+ * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
+#include <float.h> /* DBL_MANT_DIG */
+#include <inttypes.h> /* PRIu64 */
+
+/* for default trace ID generation try to fit in lua_Number, usually double */
+#define DNS_TRACE_ID_BITS DNS_PP_MIN(DBL_MANT_DIG, (sizeof (dns_trace_id_t) * CHAR_BIT)) /* assuming FLT_RADIX == 2 */
+#define DNS_TRACE_ID_MASK (((DNS_TRACE_ID_C(1) << (DNS_TRACE_ID_BITS - 1)) - 1) | (DNS_TRACE_ID_C(1) << (DNS_TRACE_ID_BITS - 1)))
+#define DNS_TRACE_ID_PRI PRIu64
+
+static inline dns_trace_id_t dns_trace_mkid(void) {
+	dns_trace_id_t id = 0;
+	unsigned r; /* return type of dns_random() */
+	const size_t id_bit = sizeof id * CHAR_BIT;
+	const size_t r_bit = sizeof r * CHAR_BIT;
+
+	for (size_t n = 0; n < id_bit; n += r_bit) {
+		r = dns_random();
+		id <<= r_bit;
+		id |= r;
+	}
+
+	return DNS_TRACE_ID_MASK & id;
+}
+
+struct dns_trace {
+	dns_atomic_t refcount;
+
+	FILE *fp;
+	dns_trace_id_t id;
+
+	struct {
+		struct dns_trace_cname {
+			char host[DNS_D_MAXNAME + 1];
+			struct sockaddr_storage addr;
+		} base[4];
+		size_t p;
+	} cnames;
+};
+
+static void dns_te_initname(struct sockaddr_storage *ss, int fd, int (*f)(int, struct sockaddr *, socklen_t *)) {
+	socklen_t n = sizeof *ss;
+
+	if (0 != f(fd, (struct sockaddr *)ss, &n))
+		goto unspec;
+
+	if (n > sizeof *ss)
+		goto unspec;
+
+	return;
+unspec:
+	memset(ss, '\0', sizeof *ss);
+	ss->ss_family = AF_UNSPEC;
+}
+
+static void dns_te_initnames(struct sockaddr_storage *local, struct sockaddr_storage *remote, int fd) {
+	dns_te_initname(local, fd, &getsockname);
+	dns_te_initname(remote, fd, &getpeername);
+}
+
+static struct dns_trace_event *dns_te_init(struct dns_trace_event *te, int type) {
+	/* NB: silence valgrind */
+	memset(te, '\0', offsetof(struct dns_trace_event, data));
+	te->type = type;
+	return te;
+}
+
+int dns_trace_abi(void) {
+	return DNS_TRACE_ABI;
+}
+
+struct dns_trace *dns_trace_open(FILE *fp, dns_error_t *error) {
+	static const struct dns_trace trace_initializer = { .refcount = 1 };
+	struct dns_trace *trace;
+
+	if (!(trace = malloc(sizeof *trace)))
+		goto syerr;
+
+	*trace = trace_initializer;
+
+	if (fp) {
+		trace->fp = fp;
+	} else if (!(fp = tmpfile())) {
+		goto syerr;
+	}
+
+	trace->id = dns_trace_mkid();
+
+	return trace;
+syerr:
+	*error = dns_syerr();
+
+	dns_trace_close(trace);
+
+	return NULL;
+} /* dns_trace_open() */
+
+void dns_trace_close(struct dns_trace *trace) {
+	if (!trace || 1 != dns_trace_release(trace))
+		return;
+
+	if (trace->fp)
+		fclose(trace->fp);
+	free(trace);
+} /* dns_trace_close() */
+
+dns_refcount_t dns_trace_acquire(struct dns_trace *trace) {
+	return dns_atomic_fetch_add(&trace->refcount);
+} /* dns_trace_acquire() */
+
+static struct dns_trace *dns_trace_acquire_p(struct dns_trace *trace) {
+	return (trace)? dns_trace_acquire(trace), trace : NULL;
+} /* dns_trace_acquire_p() */
+
+dns_refcount_t dns_trace_release(struct dns_trace *trace) {
+	return dns_atomic_fetch_sub(&trace->refcount);
+} /* dns_trace_release() */
+
+dns_trace_id_t dns_trace_id(struct dns_trace *trace) {
+	return trace->id;
+} /* dns_trace_id() */
+
+dns_trace_id_t dns_trace_setid(struct dns_trace *trace, dns_trace_id_t id) {
+	trace->id = (id)? id : dns_trace_mkid();
+	return trace->id;
+} /* dns_trace_setid() */
+
+struct dns_trace_event *dns_trace_get(struct dns_trace *trace, struct dns_trace_event **tp, dns_error_t *error) {
+	return dns_trace_fget(tp, trace->fp, error);
+} /* dns_trace_get() */
+
+dns_error_t dns_trace_put(struct dns_trace *trace, const struct dns_trace_event *te, const void *data, size_t datasize) {
+	return dns_trace_fput(te, data, datasize, trace->fp);
+} /* dns_trace_put() */
+
+struct dns_trace_event *dns_trace_tag(struct dns_trace *trace, struct dns_trace_event *te) {
+	struct timeval tv;
+
+	te->id = trace->id;
+	gettimeofday(&tv, NULL);
+	dns_tv2ts(&te->ts, &tv);
+	te->abi = DNS_TRACE_ABI;
+
+	return te;
+} /* dns_trace_tag() */
+
+static dns_error_t dns_trace_tag_and_put(struct dns_trace *trace, struct dns_trace_event *te, const void *data, size_t datasize) {
+	return dns_trace_put(trace, dns_trace_tag(trace, te), data, datasize);
+} /* dns_trace_tag_and_put() */
+
+struct dns_trace_event *dns_trace_fget(struct dns_trace_event **tp, FILE *fp, dns_error_t *error) {
+	const size_t headsize = offsetof(struct dns_trace_event, data);
+	struct dns_trace_event tmp, *te;
+	size_t n;
+
+	errno = 0;
+	if (!(n = fread(&tmp, 1, headsize, fp)))
+		goto none;
+	if (n < offsetof(struct dns_trace_event, data))
+		goto some;
+
+	if (!(te = realloc(*tp, DNS_PP_MAX(headsize, tmp.size)))) {
+		*error = errno;
+		return NULL;
+	}
+
+	*tp = te;
+	memcpy(te, &tmp, offsetof(struct dns_trace_event, data));
+
+	if (dns_te_datasize(te)) {
+		errno = 0;
+		if (!(n = fread(te->data, 1, dns_te_datasize(te), fp)))
+			goto none;
+		if (n < dns_te_datasize(te))
+			goto some;
+	}
+
+	return te;
+none:
+	*error = (ferror(fp))? errno : 0;
+	return NULL;
+some:
+	*error = 0;
+	return NULL;
+}
+
+dns_error_t dns_trace_fput(const struct dns_trace_event *te, const void *data, size_t datasize, FILE *fp) {
+	size_t headsize = offsetof(struct dns_trace_event, data);
+	struct dns_trace_event tmp;
+
+	memcpy(&tmp, te, headsize);
+	tmp.size = headsize + datasize;
+
+	/* NB: ignore seek error as fp might not point to a regular file */
+	(void)fseek(fp, 0, SEEK_END);
+
+	if (fwrite(&tmp, 1, headsize, fp) < headsize)
+		return errno;
+	if (fwrite(data, 1, datasize, fp) < datasize)
+		return errno;
+	if (fflush(fp))
+		return errno;
+
+	return 0;
+}
+
+static void dns_trace_setcname(struct dns_trace *trace, const char *host, const struct sockaddr *addr) {
+	if (!trace || !trace->fp)
+		return;
+
+	struct dns_trace_cname *cname = &trace->cnames.base[trace->cnames.p];
+	dns_strlcpy(cname->host, host, sizeof cname->host);
+	memcpy(&cname->addr, addr, DNS_PP_MIN(dns_sa_len(addr), sizeof cname->addr));
+
+	trace->cnames.p = (trace->cnames.p + 1) % lengthof(trace->cnames.base);
+}
+
+static const char *dns_trace_cname(struct dns_trace *trace, const struct sockaddr *addr) {
+	if (!trace || !trace->fp)
+		return NULL;
+
+	/* NB: start search from the write cursor to  */
+	for (const struct dns_trace_cname *cname = trace->cnames.base; cname < endof(trace->cnames.base); cname++) {
+		if (0 == dns_sa_cmp((struct sockaddr *)addr, (struct sockaddr *)&cname->addr))
+			return cname->host;
+	}
+
+	return NULL;
+}
+
+static void dns_trace_res_submit(struct dns_trace *trace, const char *qname, enum dns_type qtype, enum dns_class qclass, int error) {
+	if (!trace || !trace->fp)
+		return;
+
+	struct dns_trace_event te;
+	dns_te_init(&te, DNS_TE_RES_SUBMIT);
+	dns_strlcpy(te.res_submit.qname, qname, sizeof te.res_submit.qname);
+	te.res_submit.qtype = qtype;
+	te.res_submit.qclass = qclass;
+	te.res_submit.error = error;
+	dns_trace_tag_and_put(trace, &te, NULL, 0);
+}
+
+static void dns_trace_res_fetch(struct dns_trace *trace, const struct dns_packet *packet, int error) {
+	if (!trace || !trace->fp)
+		return;
+
+	struct dns_trace_event te;
+	dns_te_init(&te, DNS_TE_RES_FETCH);
+	const void *data = (packet)? packet->data : NULL;
+	size_t datasize = (packet)? packet->end : 0;
+	te.res_fetch.error = error;
+	dns_trace_tag_and_put(trace, &te, data, datasize);
+}
+
+static void dns_trace_so_submit(struct dns_trace *trace, const struct dns_packet *packet, const struct sockaddr *haddr, int error) {
+	if (!trace || !trace->fp)
+		return;
+
+	struct dns_trace_event te;
+	dns_te_init(&te, DNS_TE_SO_SUBMIT);
+	memcpy(&te.so_submit.haddr, haddr, DNS_PP_MIN(dns_sa_len(haddr), sizeof te.so_submit.haddr));
+	const char *cname;
+	if ((cname = dns_trace_cname(trace, haddr)))
+		dns_strlcpy(te.so_submit.hname, cname, sizeof te.so_submit.hname);
+	te.so_submit.error = error;
+	dns_trace_tag_and_put(trace, &te, packet->data, packet->end);
+}
+
+static void dns_trace_so_verify(struct dns_trace *trace, const struct dns_packet *packet, int error) {
+	if (!trace || !trace->fp)
+		return;
+
+	struct dns_trace_event te;
+	dns_te_init(&te, DNS_TE_SO_VERIFY);
+	te.so_verify.error = error;
+	dns_trace_tag_and_put(trace, &te, packet->data, packet->end);
+}
+
+static void dns_trace_so_fetch(struct dns_trace *trace, const struct dns_packet *packet, int error) {
+	if (!trace || !trace->fp)
+		return;
+
+	struct dns_trace_event te;
+	dns_te_init(&te, DNS_TE_SO_FETCH);
+	const void *data = (packet)? packet->data : NULL;
+	size_t datasize = (packet)? packet->end : 0;
+	te.so_fetch.error = error;
+	dns_trace_tag_and_put(trace, &te, data, datasize);
+}
+
+static void dns_trace_sys_connect(struct dns_trace *trace, int fd, int socktype, const struct sockaddr *dst, int error) {
+	if (!trace || !trace->fp)
+		return;
+
+	struct dns_trace_event te;
+	dns_te_init(&te, DNS_TE_SYS_CONNECT);
+	dns_te_initname(&te.sys_connect.src, fd, &getsockname);
+	memcpy(&te.sys_connect.dst, dst, DNS_PP_MIN(dns_sa_len(dst), sizeof te.sys_connect.dst));
+	te.sys_connect.socktype = socktype;
+	te.sys_connect.error = error;
+	dns_trace_tag_and_put(trace, &te, NULL, 0);
+}
+
+static void dns_trace_sys_send(struct dns_trace *trace, int fd, int socktype, const void *data, size_t datasize, int error) {
+	if (!trace || !trace->fp)
+		return;
+
+	struct dns_trace_event te;
+	dns_te_init(&te, DNS_TE_SYS_SEND);
+	dns_te_initnames(&te.sys_send.src, &te.sys_send.dst, fd);
+	te.sys_send.socktype = socktype;
+	te.sys_send.error = error;
+	dns_trace_tag_and_put(trace, &te, data, datasize);
+}
+
+static void dns_trace_sys_recv(struct dns_trace *trace, int fd, int socktype, const void *data, size_t datasize, int error) {
+	if (!trace || !trace->fp)
+		return;
+
+	struct dns_trace_event te;
+	dns_te_init(&te, DNS_TE_SYS_RECV);
+	dns_te_initnames(&te.sys_recv.dst, &te.sys_recv.src, fd);
+	te.sys_recv.socktype = socktype;
+	te.sys_recv.error = error;
+	dns_trace_tag_and_put(trace, &te, data, datasize);
+}
+
+static dns_error_t dns_trace_dump_packet(struct dns_trace *trace, const char *prefix, const unsigned char *data, size_t datasize, FILE *fp) {
+	struct dns_packet *packet = NULL;
+	char *line = NULL, *p;
+	size_t size = 1, skip = 0;
+	int error;
+
+	if (!(packet = dns_p_make(datasize, &error)))
+		goto error;
+
+	memcpy(packet->data, data, datasize);
+	packet->end = datasize;
+	(void)dns_p_study(packet);
+resize:
+	if (!(p = dns_reallocarray(line, size, 2, &error)))
+		goto error;
+	line = p;
+	size *= 2;
+
+	struct dns_rr_i records = { 0 };
+	struct dns_p_lines_i lines = { 0 };
+	size_t len, count = 0;
+
+	while ((len = dns_p_lines(line, size, &error, packet, &records, &lines))) {
+		if (!(len < size)) {
+			skip = count;
+			goto resize;
+		} else if (skip <= count) {
+			fputs(prefix, fp);
+			fwrite(line, 1, len, fp);
+		}
+		count++;
+	}
+
+	if (error)
+		goto error;
+
+	error = 0;
+error:
+	free(line);
+	dns_p_free(packet);
+
+	return error;
+}
+
+static dns_error_t dns_trace_dump_data(struct dns_trace *trace, const char *prefix, const unsigned char *data, size_t datasize, FILE *fp) {
+	struct dns_hxd_lines_i lines = { 0 };
+	char line[128];
+	size_t len;
+
+	while ((len = dns_hxd_lines(line, sizeof line, data, datasize, &lines))) {
+		if (len >= sizeof line)
+			return EOVERFLOW; /* shouldn't be possible */
+		fputs(prefix, fp);
+		fwrite(line, 1, len, fp);
+	}
+
+	return 0;
+}
+
+static dns_error_t dns_trace_dump_addr(struct dns_trace *trace, const char *prefix, const struct sockaddr_storage *ss, FILE *fp) {
+	const void *addr;
+	const char *path;
+	socklen_t len;
+	int error;
+
+	if ((addr = dns_sa_addr(ss->ss_family, (struct sockaddr *)ss, NULL))) {
+		char ip[INET6_ADDRSTRLEN + 1];
+
+		if ((error = dns_ntop(ss->ss_family, addr, ip, sizeof ip)))
+			return error;
+		fprintf(fp, "%s%s\n", prefix, ip);
+	} else if ((path = dns_sa_path((struct sockaddr *)ss, &len))) {
+		fprintf(fp, "%sunix:%.*s", prefix, (int)len, path);
+	} else {
+		return EINVAL;
+	}
+
+	return 0;
+}
+
+static dns_error_t dns_trace_dump_meta(struct dns_trace *trace, const char *prefix, const struct dns_trace_event *te, dns_microseconds_t elapsed, FILE *fp) {
+	char time_s[48], elapsed_s[48];
+
+	dns_utime_print(time_s, sizeof time_s, dns_ts2us(&te->ts, 0));
+	dns_utime_print(elapsed_s, sizeof elapsed_s, elapsed);
+
+	fprintf(fp, "%sid: %"DNS_TRACE_ID_PRI"\n", prefix, te->id);
+	fprintf(fp, "%sts: %s (%s)\n", prefix, time_s, elapsed_s);
+	fprintf(fp, "%sabi: 0x%x (0x%x)\n", prefix, te->abi, DNS_TRACE_ABI);
+	return 0;
+}
+
+static dns_error_t dns_trace_dump_error(struct dns_trace *trace, const char *prefix, int error, FILE *fp) {
+	fprintf(fp, "%s%d (%s)\n", prefix, error, (error)? dns_strerror(error) : "none");
+	return 0;
+}
+
+dns_error_t dns_trace_dump(struct dns_trace *trace, FILE *fp) {
+	struct dns_trace_event *te = NULL;
+	struct {
+		dns_trace_id_t id;
+		dns_microseconds_t begin, elapsed;
+	} state = { 0 };
+	int error;
+
+	if (!trace || !trace->fp)
+		return EINVAL;
+
+	if (0 != fseek(trace->fp, 0, SEEK_SET))
+		goto syerr;
+
+	while (dns_trace_fget(&te, trace->fp, &error)) {
+		size_t datasize = dns_te_datasize(te);
+		const unsigned char *data = (datasize)? te->data : NULL;
+
+		if (state.id != te->id) {
+			state.id = te->id;
+			state.begin = dns_ts2us(&te->ts, 0);
+		}
+		dns_time_diff(&state.elapsed, dns_ts2us(&te->ts, 0), state.begin);
+
+		switch(te->type) {
+		case DNS_TE_RES_SUBMIT:
+			fprintf(fp, "dns_res_submit:\n");
+			dns_trace_dump_meta(trace, "  ", te, state.elapsed, fp);
+			fprintf(fp, "  qname: %s\n", te->res_submit.qname);
+			fprintf(fp, "  qtype: %s\n", dns_strtype(te->res_submit.qtype));
+			fprintf(fp, "  qclass: %s\n", dns_strclass(te->res_submit.qclass));
+			dns_trace_dump_error(trace, "  error: ", te->res_submit.error, fp);
+			break;
+		case DNS_TE_RES_FETCH:
+			fprintf(fp, "dns_res_fetch:\n");
+			dns_trace_dump_meta(trace, "  ", te, state.elapsed, fp);
+			dns_trace_dump_error(trace, "  error: ", te->res_fetch.error, fp);
+
+			if (data) {
+				fprintf(fp, "  packet: |\n");
+				if ((error = dns_trace_dump_packet(trace, "    ", data, datasize, fp)))
+					goto error;
+				fprintf(fp, "  data: |\n");
+				if ((error = dns_trace_dump_data(trace, "    ", data, datasize, fp)))
+					goto error;
+			}
+
+			break;
+		case DNS_TE_SO_SUBMIT:
+			fprintf(fp, "dns_so_submit:\n");
+			dns_trace_dump_meta(trace, "  ", te, state.elapsed, fp);
+			fprintf(fp, "  hname: %s\n", te->so_submit.hname);
+			dns_trace_dump_addr(trace, "  haddr: ", &te->so_submit.haddr, fp);
+			dns_trace_dump_error(trace, "  error: ", te->so_submit.error, fp);
+
+			if (data) {
+				fprintf(fp, "  packet: |\n");
+				if ((error = dns_trace_dump_packet(trace, "    ", data, datasize, fp)))
+					goto error;
+				fprintf(fp, "  data: |\n");
+				if ((error = dns_trace_dump_data(trace, "    ", data, datasize, fp)))
+					goto error;
+			}
+
+			break;
+		case DNS_TE_SO_VERIFY:
+			fprintf(fp, "dns_so_verify:\n");
+			dns_trace_dump_meta(trace, "  ", te, state.elapsed, fp);
+			dns_trace_dump_error(trace, "  error: ", te->so_verify.error, fp);
+
+			if (data) {
+				fprintf(fp, "  packet: |\n");
+				if ((error = dns_trace_dump_packet(trace, "    ", data, datasize, fp)))
+					goto error;
+				fprintf(fp, "  data: |\n");
+				if ((error = dns_trace_dump_data(trace, "    ", data, datasize, fp)))
+					goto error;
+			}
+
+			break;
+		case DNS_TE_SO_FETCH:
+			fprintf(fp, "dns_so_fetch:\n");
+			dns_trace_dump_meta(trace, "  ", te, state.elapsed, fp);
+			dns_trace_dump_error(trace, "  error: ", te->so_fetch.error, fp);
+
+			if (data) {
+				fprintf(fp, "  packet: |\n");
+				if ((error = dns_trace_dump_packet(trace, "    ", data, datasize, fp)))
+					goto error;
+				fprintf(fp, "  data: |\n");
+				if ((error = dns_trace_dump_data(trace, "    ", data, datasize, fp)))
+					goto error;
+			}
+
+			break;
+		case DNS_TE_SYS_CONNECT: {
+			fprintf(fp, "dns_sys_connect:\n");
+			dns_trace_dump_meta(trace, "  ", te, state.elapsed, fp);
+			dns_trace_dump_addr(trace, "  src: ", &te->sys_connect.src, fp);
+			dns_trace_dump_addr(trace, "  dst: ", &te->sys_connect.dst, fp);
+			int socktype = te->sys_connect.socktype;
+			fprintf(fp, "  socktype: %d (%s)\n", socktype, ((socktype == SOCK_STREAM)? "SOCK_STREAM" : (socktype == SOCK_DGRAM)? "SOCK_DGRAM" : "?"));
+			dns_trace_dump_error(trace, "  error: ", te->sys_connect.error, fp);
+
+			break;
+		}
+		case DNS_TE_SYS_SEND: {
+			fprintf(fp, "dns_sys_send:\n");
+			dns_trace_dump_meta(trace, "  ", te, state.elapsed, fp);
+			dns_trace_dump_addr(trace, "  src: ", &te->sys_send.src, fp);
+			dns_trace_dump_addr(trace, "  dst: ", &te->sys_send.dst, fp);
+			int socktype = te->sys_send.socktype;
+			fprintf(fp, "  socktype: %d (%s)\n", socktype, ((socktype == SOCK_STREAM)? "SOCK_STREAM" : (socktype == SOCK_DGRAM)? "SOCK_DGRAM" : "?"));
+			dns_trace_dump_error(trace, "  error: ", te->sys_send.error, fp);
+
+			if (data) {
+				fprintf(fp, "  data: |\n");
+				if ((error = dns_trace_dump_data(trace, "    ", data, datasize, fp)))
+					goto error;
+			}
+
+			break;
+		}
+		case DNS_TE_SYS_RECV: {
+			fprintf(fp, "dns_sys_recv:\n");
+			dns_trace_dump_meta(trace, "  ", te, state.elapsed, fp);
+			dns_trace_dump_addr(trace, "  src: ", &te->sys_recv.src, fp);
+			dns_trace_dump_addr(trace, "  dst: ", &te->sys_recv.dst, fp);
+			int socktype = te->sys_recv.socktype;
+			fprintf(fp, "  socktype: %d (%s)\n", socktype, ((socktype == SOCK_STREAM)? "SOCK_STREAM" : (socktype == SOCK_DGRAM)? "SOCK_DGRAM" : "?"));
+			dns_trace_dump_error(trace, "  error: ", te->sys_recv.error, fp);
+
+			if (data) {
+				fprintf(fp, "  data: |\n");
+				if ((error = dns_trace_dump_data(trace, "    ", data, datasize, fp)))
+					goto error;
+			}
+
+			break;
+		}
+		default:
+			fprintf(fp, "unknown(0x%.2x):\n", te->type);
+			dns_trace_dump_meta(trace, "  ", te, state.elapsed, fp);
+
+			if (data) {
+				fprintf(fp, "  data: |\n");
+				if ((error = dns_trace_dump_data(trace, "    ", data, datasize, fp)))
+					goto error;
+			}
+
+			break;
+		}
+	}
+
+	goto epilog;
+syerr:
+	error = errno;
+error:
+	(void)0;
+epilog:
+	free(te);
+
+	return error;
+}
+
+/*
+ * H O S T S  R O U T I N E S
+ *
+ * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
+
+struct dns_hosts {
+	struct dns_hosts_entry {
+		char host[DNS_D_MAXNAME + 1];
+		char arpa[73 + 1];
+
+		int af;
+
+		union {
+			struct in_addr a4;
+			struct in6_addr a6;
+		} addr;
+
+		_Bool alias;
+
+		struct dns_hosts_entry *next;
+	} *head, **tail;
+
+	dns_atomic_t refcount;
+}; /* struct dns_hosts */
+
+
+struct dns_hosts *dns_hosts_open(int *error) {
+	static const struct dns_hosts hosts_initializer	= { .refcount = 1 };
+	struct dns_hosts *hosts;
+
+	if (!(hosts = malloc(sizeof *hosts)))
+		goto syerr;
+
+	*hosts	= hosts_initializer;
+
+	hosts->tail	= &hosts->head;
+
+	return hosts;
+syerr:
+	*error	= dns_syerr();
+
+	free(hosts);
+
+	return 0;
+} /* dns_hosts_open() */
+
+
+void dns_hosts_close(struct dns_hosts *hosts) {
+	struct dns_hosts_entry *ent, *xnt;
+
+	if (!hosts || 1 != dns_hosts_release(hosts))
+		return;
+
+	for (ent = hosts->head; ent; ent = xnt) {
+		xnt	= ent->next;
+
+		free(ent);
+	}
+
+	free(hosts);
+
+	return;
+} /* dns_hosts_close() */
+
+
+dns_refcount_t dns_hosts_acquire(struct dns_hosts *hosts) {
+	return dns_atomic_fetch_add(&hosts->refcount);
+} /* dns_hosts_acquire() */
+
+
+dns_refcount_t dns_hosts_release(struct dns_hosts *hosts) {
+	return dns_atomic_fetch_sub(&hosts->refcount);
+} /* dns_hosts_release() */
+
+
+struct dns_hosts *dns_hosts_mortal(struct dns_hosts *hosts) {
+	if (hosts)
+		dns_hosts_release(hosts);
+
+	return hosts;
+} /* dns_hosts_mortal() */
+
+
+struct dns_hosts *dns_hosts_local(int *error_) {
+	struct dns_hosts *hosts;
+	int error;
+
+	if (!(hosts = dns_hosts_open(&error)))
+		goto error;
+
+	if ((error = dns_hosts_loadpath(hosts, "/etc/hosts")))
+		goto error;
+
+	return hosts;
+error:
+	*error_	= error;
+
+	dns_hosts_close(hosts);
+
+	return 0;
+} /* dns_hosts_local() */
+
+
+#define dns_hosts_issep(ch)	(dns_isspace(ch))
+#define dns_hosts_iscom(ch)	((ch) == '#' || (ch) == ';')
+
+int dns_hosts_loadfile(struct dns_hosts *hosts, FILE *fp) {
+	struct dns_hosts_entry ent;
+	char word[DNS_PP_MAX(INET6_ADDRSTRLEN, DNS_D_MAXNAME) + 1];
+	unsigned wp, wc, skip;
+	int ch, error;
+
+	rewind(fp);
+
+	do {
+		memset(&ent, '\0', sizeof ent);
+		wc	= 0;
+		skip	= 0;
+
+		do {
+			memset(word, '\0', sizeof word);
+			wp	= 0;
+
+			while (EOF != (ch = fgetc(fp)) && ch != '\n') {
+				skip	|= !!dns_hosts_iscom(ch);
+
+				if (skip)
+					continue;
+
+				if (dns_hosts_issep(ch))
+					break;
+
+				if (wp < sizeof word - 1)
+					word[wp]	= ch;
+				wp++;
+			}
+
+			if (!wp)
+				continue;
+
+			wc++;
+
+			switch (wc) {
+			case 0:
+				break;
+			case 1:
+				ent.af	= (strchr(word, ':'))? AF_INET6 : AF_INET;
+				skip	= (1 != dns_inet_pton(ent.af, word, &ent.addr));
+
+				break;
+			default:
+				if (!wp)
+					break;
+
+				dns_d_anchor(ent.host, sizeof ent.host, word, wp);
+
+				if ((error = dns_hosts_insert(hosts, ent.af, &ent.addr, ent.host, (wc > 2))))
+					return error;
+
+				break;
+			} /* switch() */
+		} while (ch != EOF && ch != '\n');
+	} while (ch != EOF);
+
+	return 0;
+} /* dns_hosts_loadfile() */
+
+
+int dns_hosts_loadpath(struct dns_hosts *hosts, const char *path) {
+	FILE *fp;
+	int error;
+
+	if (!(fp = dns_fopen(path, "rt", &error)))
+		return error;
+
+	error = dns_hosts_loadfile(hosts, fp);
+
+	fclose(fp);
+
+	return error;
+} /* dns_hosts_loadpath() */
+
+
+int dns_hosts_dump(struct dns_hosts *hosts, FILE *fp) {
+	struct dns_hosts_entry *ent, *xnt;
+	char addr[INET6_ADDRSTRLEN + 1];
+	unsigned i;
+
+	for (ent = hosts->head; ent; ent = xnt) {
+		xnt	= ent->next;
+
+		dns_inet_ntop(ent->af, &ent->addr, addr, sizeof addr);
+
+		fputs(addr, fp);
+
+		for (i = strlen(addr); i < INET_ADDRSTRLEN; i++)
+			fputc(' ', fp);
+
+		fputc(' ', fp);
+
+		fputs(ent->host, fp);
+		fputc('\n', fp);
+	}
+
+	return 0;
+} /* dns_hosts_dump() */
+
+
+int dns_hosts_insert(struct dns_hosts *hosts, int af, const void *addr, const void *host, _Bool alias) {
+	struct dns_hosts_entry *ent;
+	int error;
+
+	if (!(ent = malloc(sizeof *ent)))
+		goto syerr;
+
+	dns_d_anchor(ent->host, sizeof ent->host, host, strlen(host));
+
+	switch ((ent->af = af)) {
+	case AF_INET6:
+		memcpy(&ent->addr.a6, addr, sizeof ent->addr.a6);
+
+		dns_aaaa_arpa(ent->arpa, sizeof ent->arpa, addr);
+
+		break;
+	case AF_INET:
+		memcpy(&ent->addr.a4, addr, sizeof ent->addr.a4);
+
+		dns_a_arpa(ent->arpa, sizeof ent->arpa, addr);
+
+		break;
+	default:
+		error	= EINVAL;
+
+		goto error;
+	} /* switch() */
+
+	ent->alias	= alias;
+
+	ent->next	= 0;
+	*hosts->tail	= ent;
+	hosts->tail	= &ent->next;
+
+	return 0;
+syerr:
+	error	= dns_syerr();
+error:
+	free(ent);
+
+	return error;
+} /* dns_hosts_insert() */
+
+
+struct dns_packet *dns_hosts_query(struct dns_hosts *hosts, struct dns_packet *Q, int *error_) {
+	struct dns_packet *P	= dns_p_new(512);
+	struct dns_packet *A	= 0;
+	struct dns_rr rr;
+	struct dns_hosts_entry *ent;
+	int error, af;
+	char qname[DNS_D_MAXNAME + 1];
+	size_t qlen;
+
+	if ((error = dns_rr_parse(&rr, 12, Q)))
+		goto error;
+
+	if (!(qlen = dns_d_expand(qname, sizeof qname, rr.dn.p, Q, &error)))
+		goto error;
+	else if (qlen >= sizeof qname)
+		goto toolong;
+
+	if ((error = dns_p_push(P, DNS_S_QD, qname, qlen, rr.type, rr.class, 0, 0)))
+		goto error;
+
+	switch (rr.type) {
+	case DNS_T_PTR:
+		for (ent = hosts->head; ent; ent = ent->next) {
+			if (ent->alias || 0 != strcasecmp(qname, ent->arpa))
+				continue;
+
+			if ((error = dns_p_push(P, DNS_S_AN, qname, qlen, rr.type, rr.class, 0, ent->host)))
+				goto error;
+		}
+
+		break;
+	case DNS_T_AAAA:
+		af	= AF_INET6;
+
+		goto loop;
+	case DNS_T_A:
+		af	= AF_INET;
+
+loop:		for (ent = hosts->head; ent; ent = ent->next) {
+			if (ent->af != af || 0 != strcasecmp(qname, ent->host))
+				continue;
+
+			if ((error = dns_p_push(P, DNS_S_AN, qname, qlen, rr.type, rr.class, 0, &ent->addr)))
+				goto error;
+		}
+
+		break;
+	default:
+		break;
+	} /* switch() */
+
+
+	if (!(A = dns_p_copy(dns_p_make(P->end, &error), P)))
+		goto error;
+
+	return A;
+toolong:
+	error = DNS_EILLEGAL;
+error:
+	*error_	= error;
+
+	dns_p_free(A);
+
+	return 0;
+} /* dns_hosts_query() */
+
+
+/*
+ * R E S O L V . C O N F  R O U T I N E S
+ *
+ * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
+
+struct dns_resolv_conf *dns_resconf_open(int *error) {
+	static const struct dns_resolv_conf resconf_initializer = {
+		.lookup = "bf",
+		.family = { AF_INET, AF_INET6 },
+		.options = { .ndots = 1, .timeout = 5, .attempts = 2, .tcp = DNS_RESCONF_TCP_ENABLE, },
+		.iface = { .ss_family = AF_INET },
+	};
+	struct dns_resolv_conf *resconf;
+	struct sockaddr_in *sin;
+
+	if (!(resconf = malloc(sizeof *resconf)))
+		goto syerr;
+
+	*resconf = resconf_initializer;
+
+	sin = (struct sockaddr_in *)&resconf->nameserver[0];
+	sin->sin_family      = AF_INET;
+	sin->sin_addr.s_addr = INADDR_ANY;
+	sin->sin_port        = htons(53);
+#if defined(SA_LEN)
+	sin->sin_len         = sizeof *sin;
+#endif
+
+	if (0 != gethostname(resconf->search[0], sizeof resconf->search[0]))
+		goto syerr;
+
+	dns_d_anchor(resconf->search[0], sizeof resconf->search[0], resconf->search[0], strlen(resconf->search[0]));
+	dns_d_cleave(resconf->search[0], sizeof resconf->search[0], resconf->search[0], strlen(resconf->search[0]));
+
+	/*
+	 * XXX: If gethostname() returned a string without any label
+	 *      separator, then search[0][0] should be NUL.
+	 */
+
+	dns_resconf_acquire(resconf);
+
+	return resconf;
+syerr:
+	*error	= dns_syerr();
+
+	free(resconf);
+
+	return 0;
+} /* dns_resconf_open() */
+
+
+void dns_resconf_close(struct dns_resolv_conf *resconf) {
+	if (!resconf || 1 != dns_resconf_release(resconf))
+		return /* void */;
+
+	free(resconf);
+} /* dns_resconf_close() */
+
+
+dns_refcount_t dns_resconf_acquire(struct dns_resolv_conf *resconf) {
+	return dns_atomic_fetch_add(&resconf->_.refcount);
+} /* dns_resconf_acquire() */
+
+
+dns_refcount_t dns_resconf_release(struct dns_resolv_conf *resconf) {
+	return dns_atomic_fetch_sub(&resconf->_.refcount);
+} /* dns_resconf_release() */
+
+
+struct dns_resolv_conf *dns_resconf_mortal(struct dns_resolv_conf *resconf) {
+	if (resconf)
+		dns_resconf_release(resconf);
+
+	return resconf;
+} /* dns_resconf_mortal() */
+
+
+struct dns_resolv_conf *dns_resconf_local(int *error_) {
+	struct dns_resolv_conf *resconf;
+	int error;
+
+	if (!(resconf = dns_resconf_open(&error)))
+		goto error;
+
+	if ((error = dns_resconf_loadpath(resconf, "/etc/resolv.conf"))) {
+		/*
+		 * NOTE: Both the glibc and BIND9 resolvers ignore a missing
+		 * /etc/resolv.conf, defaulting to a nameserver of
+		 * 127.0.0.1. See also dns_hints_insert_resconf, and the
+		 * default initialization of nameserver[0] in
+		 * dns_resconf_open.
+		 */
+		if (error != ENOENT)
+			goto error;
+	}
+
+	if ((error = dns_nssconf_loadpath(resconf, "/etc/nsswitch.conf"))) {
+		if (error != ENOENT)
+			goto error;
+	}
+
+	return resconf;
+error:
+	*error_	= error;
+
+	dns_resconf_close(resconf);
+
+	return 0;
+} /* dns_resconf_local() */
+
+
+struct dns_resolv_conf *dns_resconf_root(int *error) {
+	struct dns_resolv_conf *resconf;
+
+	if ((resconf = dns_resconf_local(error)))
+		resconf->options.recurse = 1;
+
+	return resconf;
+} /* dns_resconf_root() */
+
+
+static time_t dns_resconf_timeout(const struct dns_resolv_conf *resconf) {
+	return (time_t)DNS_PP_MIN(INT_MAX, resconf->options.timeout);
+} /* dns_resconf_timeout() */
+
+
+enum dns_resconf_keyword {
+	DNS_RESCONF_NAMESERVER,
+	DNS_RESCONF_DOMAIN,
+	DNS_RESCONF_SEARCH,
+	DNS_RESCONF_LOOKUP,
+	DNS_RESCONF_FILE,
+	DNS_RESCONF_BIND,
+	DNS_RESCONF_CACHE,
+	DNS_RESCONF_FAMILY,
+	DNS_RESCONF_INET4,
+	DNS_RESCONF_INET6,
+	DNS_RESCONF_OPTIONS,
+	DNS_RESCONF_EDNS0,
+	DNS_RESCONF_NDOTS,
+	DNS_RESCONF_TIMEOUT,
+	DNS_RESCONF_ATTEMPTS,
+	DNS_RESCONF_ROTATE,
+	DNS_RESCONF_RECURSE,
+	DNS_RESCONF_SMART,
+	DNS_RESCONF_TCP,
+	DNS_RESCONF_TCPx,
+	DNS_RESCONF_INTERFACE,
+	DNS_RESCONF_ZERO,
+	DNS_RESCONF_ONE,
+	DNS_RESCONF_ENABLE,
+	DNS_RESCONF_ONLY,
+	DNS_RESCONF_DISABLE,
+}; /* enum dns_resconf_keyword */
+
+static enum dns_resconf_keyword dns_resconf_keyword(const char *word) {
+	static const char *words[]	= {
+		[DNS_RESCONF_NAMESERVER]	= "nameserver",
+		[DNS_RESCONF_DOMAIN]		= "domain",
+		[DNS_RESCONF_SEARCH]		= "search",
+		[DNS_RESCONF_LOOKUP]		= "lookup",
+		[DNS_RESCONF_FILE]		= "file",
+		[DNS_RESCONF_BIND]		= "bind",
+		[DNS_RESCONF_CACHE]		= "cache",
+		[DNS_RESCONF_FAMILY]		= "family",
+		[DNS_RESCONF_INET4]		= "inet4",
+		[DNS_RESCONF_INET6]		= "inet6",
+		[DNS_RESCONF_OPTIONS]		= "options",
+		[DNS_RESCONF_EDNS0]		= "edns0",
+		[DNS_RESCONF_ROTATE]		= "rotate",
+		[DNS_RESCONF_RECURSE]		= "recurse",
+		[DNS_RESCONF_SMART]		= "smart",
+		[DNS_RESCONF_TCP]		= "tcp",
+		[DNS_RESCONF_INTERFACE]		= "interface",
+		[DNS_RESCONF_ZERO]		= "0",
+		[DNS_RESCONF_ONE]		= "1",
+		[DNS_RESCONF_ENABLE]		= "enable",
+		[DNS_RESCONF_ONLY]		= "only",
+		[DNS_RESCONF_DISABLE]		= "disable",
+	};
+	unsigned i;
+
+	for (i = 0; i < lengthof(words); i++) {
+		if (words[i] && 0 == strcasecmp(words[i], word))
+			return i;
+	}
+
+	if (0 == strncasecmp(word, "ndots:", sizeof "ndots:" - 1))
+		return DNS_RESCONF_NDOTS;
+
+	if (0 == strncasecmp(word, "timeout:", sizeof "timeout:" - 1))
+		return DNS_RESCONF_TIMEOUT;
+
+	if (0 == strncasecmp(word, "attempts:", sizeof "attempts:" - 1))
+		return DNS_RESCONF_ATTEMPTS;
+
+	if (0 == strncasecmp(word, "tcp:", sizeof "tcp:" - 1))
+		return DNS_RESCONF_TCPx;
+
+	return -1;
+} /* dns_resconf_keyword() */
+
+
+/** OpenBSD-style "[1.2.3.4]:53" nameserver syntax */
+int dns_resconf_pton(struct sockaddr_storage *ss, const char *src) {
+	struct { char buf[128], *p; } addr = { "", addr.buf };
+	unsigned short port = 0;
+	int ch, af = AF_INET, error;
+
+	while ((ch = *src++)) {
+		switch (ch) {
+		case ' ':
+			/* FALL THROUGH */
+		case '\t':
+			break;
+		case '[':
+			break;
+		case ']':
+			while ((ch = *src++)) {
+				if (dns_isdigit(ch)) {
+					port *= 10;
+					port += ch - '0';
+				}
+			}
+
+			goto inet;
+		case ':':
+			af = AF_INET6;
+
+			/* FALL THROUGH */
+		default:
+			if (addr.p < endof(addr.buf) - 1)
+				*addr.p++ = ch;
+
+			break;
+		} /* switch() */
+	} /* while() */
+inet:
+
+	if ((error = dns_pton(af, addr.buf, dns_sa_addr(af, ss, NULL))))
+		return error;
+
+	port = (!port)? 53 : port;
+	*dns_sa_port(af, ss) = htons(port);
+	dns_sa_family(ss) = af;
+
+	return 0;
+} /* dns_resconf_pton() */
+
+#define dns_resconf_issep(ch)	(dns_isspace(ch) || (ch) == ',')
+#define dns_resconf_iscom(ch)	((ch) == '#' || (ch) == ';')
+
+int dns_resconf_loadfile(struct dns_resolv_conf *resconf, FILE *fp) {
+	unsigned sa_count	= 0;
+	char words[6][DNS_D_MAXNAME + 1];
+	unsigned wp, wc, i, j, n;
+	int ch, error;
+
+	rewind(fp);
+
+	do {
+		memset(words, '\0', sizeof words);
+		wp	= 0;
+		wc	= 0;
+
+		while (EOF != (ch = getc(fp)) && ch != '\n') {
+			if (dns_resconf_issep(ch)) {
+				if (wp > 0) {
+					wp	= 0;
+
+					if (++wc >= lengthof(words))
+						goto skip;
+				}
+			} else if (dns_resconf_iscom(ch)) {
+skip:
+				do {
+					ch	= getc(fp);
+				} while (ch != EOF && ch != '\n');
+
+				break;
+			} else if (wp < sizeof words[wc] - 1) {
+				words[wc][wp++] = ch;
+			} else {
+				wp = 0; /* drop word */
+				goto skip;
+			}
+		}
+
+		if (wp > 0)
+			wc++;
+
+		if (wc < 2)
+			continue;
+
+		switch (dns_resconf_keyword(words[0])) {
+		case DNS_RESCONF_NAMESERVER:
+			if (sa_count >= lengthof(resconf->nameserver))
+				continue;
+
+			if ((error = dns_resconf_pton(&resconf->nameserver[sa_count], words[1])))
+				continue;
+
+			sa_count++;
+
+			break;
+		case DNS_RESCONF_DOMAIN:
+		case DNS_RESCONF_SEARCH:
+			memset(resconf->search, '\0', sizeof resconf->search);
+
+			for (i = 1, j = 0; i < wc && j < lengthof(resconf->search); i++, j++)
+				dns_d_anchor(resconf->search[j], sizeof resconf->search[j], words[i], strlen(words[i]));
+
+			break;
+		case DNS_RESCONF_LOOKUP:
+			for (i = 1, j = 0; i < wc && j < lengthof(resconf->lookup); i++) {
+				switch (dns_resconf_keyword(words[i])) {
+				case DNS_RESCONF_FILE:
+					resconf->lookup[j++]	= 'f';
+
+					break;
+				case DNS_RESCONF_BIND:
+					resconf->lookup[j++]	= 'b';
+
+					break;
+				case DNS_RESCONF_CACHE:
+					resconf->lookup[j++]	= 'c';
+
+					break;
+				default:
+					break;
+				} /* switch() */
+			} /* for() */
+
+			break;
+		case DNS_RESCONF_FAMILY:
+			for (i = 1, j = 0; i < wc && j < lengthof(resconf->family); i++) {
+				switch (dns_resconf_keyword(words[i])) {
+				case DNS_RESCONF_INET4:
+					resconf->family[j++]	= AF_INET;
+
+					break;
+				case DNS_RESCONF_INET6:
+					resconf->family[j++]	= AF_INET6;
+
+					break;
+				default:
+					break;
+				}
+			}
+
+			break;
+		case DNS_RESCONF_OPTIONS:
+			for (i = 1; i < wc; i++) {
+				switch (dns_resconf_keyword(words[i])) {
+				case DNS_RESCONF_EDNS0:
+					resconf->options.edns0	= 1;
+
+					break;
+				case DNS_RESCONF_NDOTS:
+					for (j = sizeof "ndots:" - 1, n = 0; dns_isdigit(words[i][j]); j++) {
+						n	*= 10;
+						n	+= words[i][j] - '0';
+					} /* for() */
+
+					resconf->options.ndots	= n;
+
+					break;
+				case DNS_RESCONF_TIMEOUT:
+					for (j = sizeof "timeout:" - 1, n = 0; dns_isdigit(words[i][j]); j++) {
+						n	*= 10;
+						n	+= words[i][j] - '0';
+					} /* for() */
+
+					resconf->options.timeout	= n;
+
+					break;
+				case DNS_RESCONF_ATTEMPTS:
+					for (j = sizeof "attempts:" - 1, n = 0; dns_isdigit(words[i][j]); j++) {
+						n	*= 10;
+						n	+= words[i][j] - '0';
+					} /* for() */
+
+					resconf->options.attempts	= n;
+
+					break;
+				case DNS_RESCONF_ROTATE:
+					resconf->options.rotate		= 1;
+
+					break;
+				case DNS_RESCONF_RECURSE:
+					resconf->options.recurse	= 1;
+
+					break;
+				case DNS_RESCONF_SMART:
+					resconf->options.smart		= 1;
+
+					break;
+				case DNS_RESCONF_TCP:
+					resconf->options.tcp		= DNS_RESCONF_TCP_ONLY;
+
+					break;
+				case DNS_RESCONF_TCPx:
+					switch (dns_resconf_keyword(&words[i][sizeof "tcp:" - 1])) {
+					case DNS_RESCONF_ENABLE:
+						resconf->options.tcp	= DNS_RESCONF_TCP_ENABLE;
+
+						break;
+					case DNS_RESCONF_ONE:
+					case DNS_RESCONF_ONLY:
+						resconf->options.tcp	= DNS_RESCONF_TCP_ONLY;
+
+						break;
+					case DNS_RESCONF_ZERO:
+					case DNS_RESCONF_DISABLE:
+						resconf->options.tcp	= DNS_RESCONF_TCP_DISABLE;
+
+						break;
+					default:
+						break;
+					} /* switch() */
+
+					break;
+				default:
+					break;
+				} /* switch() */
+			} /* for() */
+
+			break;
+		case DNS_RESCONF_INTERFACE:
+			for (i = 0, n = 0; dns_isdigit(words[2][i]); i++) {
+				n	*= 10;
+				n	+= words[2][i] - '0';
+			}
+
+			dns_resconf_setiface(resconf, words[1], n);
+
+			break;
+		default:
+			break;
+		} /* switch() */
+	} while (ch != EOF);
+
+	return 0;
+} /* dns_resconf_loadfile() */
+
+
+int dns_resconf_loadpath(struct dns_resolv_conf *resconf, const char *path) {
+	FILE *fp;
+	int error;
+
+	if (!(fp = dns_fopen(path, "rt", &error)))
+		return error;
+
+	error = dns_resconf_loadfile(resconf, fp);
+
+	fclose(fp);
+
+	return error;
+} /* dns_resconf_loadpath() */
+
+
+struct dns_anyconf {
+	char *token[16];
+	unsigned count;
+	char buffer[1024], *tp, *cp;
+}; /* struct dns_anyconf */
+
+
+static void dns_anyconf_reset(struct dns_anyconf *cf) {
+	cf->count = 0;
+	cf->tp = cf->cp = cf->buffer;
+} /* dns_anyconf_reset() */
+
+
+static int dns_anyconf_push(struct dns_anyconf *cf) {
+	if (!(cf->cp < endof(cf->buffer) && cf->count < lengthof(cf->token)))
+		return ENOMEM;
+
+	*cf->cp++ = '\0';
+	cf->token[cf->count++] = cf->tp;
+	cf->tp = cf->cp;
+
+	return 0;
+} /* dns_anyconf_push() */
+
+
+static void dns_anyconf_pop(struct dns_anyconf *cf) {
+	if (cf->count > 0) {
+		--cf->count;
+		cf->tp = cf->cp = cf->token[cf->count];
+		cf->token[cf->count] = 0;
+	}
+} /* dns_anyconf_pop() */
+
+
+static int dns_anyconf_addc(struct dns_anyconf *cf, int ch) {
+	if (!(cf->cp < endof(cf->buffer)))
+		return ENOMEM;
+
+	*cf->cp++ = ch;
+
+	return 0;
+} /* dns_anyconf_addc() */
+
+
+static _Bool dns_anyconf_match(const char *pat, int mc) {
+	_Bool match;
+	int pc;
+
+	if (*pat == '^') {
+		match = 0;
+		++pat;
+	} else {
+		match = 1;
+	}
+
+	while ((pc = *(const unsigned char *)pat++)) {
+		switch (pc) {
+		case '%':
+			if (!(pc = *(const unsigned char *)pat++))
+				return !match;
+
+			switch (pc) {
+			case 'a':
+				if (dns_isalpha(mc))
+					return match;
+				break;
+			case 'd':
+				if (dns_isdigit(mc))
+					return match;
+				break;
+			case 'w':
+				if (dns_isalnum(mc))
+					return match;
+				break;
+			case 's':
+				if (dns_isspace(mc))
+					return match;
+				break;
+			default:
+				if (mc == pc)
+					return match;
+				break;
+			} /* switch() */
+
+			break;
+		default:
+			if (mc == pc)
+				return match;
+			break;
+		} /* switch() */
+	} /* while() */
+
+	return !match;
+} /* dns_anyconf_match() */
+
+
+static int dns_anyconf_peek(FILE *fp) {
+	int ch;
+	ch = getc(fp);
+	ungetc(ch, fp);
+	return ch;
+} /* dns_anyconf_peek() */
+
+
+static size_t dns_anyconf_skip(const char *pat, FILE *fp) {
+	size_t count = 0;
+	int ch;
+
+	while (EOF != (ch = getc(fp))) {
+		if (dns_anyconf_match(pat, ch)) {
+			count++;
+			continue;
+		}
+
+		ungetc(ch, fp);
+
+		break;
+	}
+
+	return count;
+} /* dns_anyconf_skip() */
+
+
+static size_t dns_anyconf_scan(struct dns_anyconf *cf, const char *pat, FILE *fp, int *error) {
+	size_t len;
+	int ch;
+
+	while (EOF != (ch = getc(fp))) {
+		if (dns_anyconf_match(pat, ch)) {
+			if ((*error = dns_anyconf_addc(cf, ch)))
+				return 0;
+
+			continue;
+		} else {
+			ungetc(ch, fp);
+
+			break;
+		}
+	}
+
+	if ((len = cf->cp - cf->tp)) {
+		if ((*error = dns_anyconf_push(cf)))
+			return 0;
+
+		return len;
+	} else {
+		*error = 0;
+
+		return 0;
+	}
+} /* dns_anyconf_scan() */
+
+
+DNS_NOTUSED static void dns_anyconf_dump(struct dns_anyconf *cf, FILE *fp) {
+	unsigned i;
+
+	fprintf(fp, "tokens:");
+
+	for (i = 0; i < cf->count; i++) {
+		fprintf(fp, " %s", cf->token[i]);
+	}
+
+	fputc('\n', fp);
+} /* dns_anyconf_dump() */
+
+
+enum dns_nssconf_keyword {
+	DNS_NSSCONF_INVALID = 0,
+	DNS_NSSCONF_HOSTS   = 1,
+	DNS_NSSCONF_SUCCESS,
+	DNS_NSSCONF_NOTFOUND,
+	DNS_NSSCONF_UNAVAIL,
+	DNS_NSSCONF_TRYAGAIN,
+	DNS_NSSCONF_CONTINUE,
+	DNS_NSSCONF_RETURN,
+	DNS_NSSCONF_FILES,
+	DNS_NSSCONF_DNS,
+	DNS_NSSCONF_MDNS,
+
+	DNS_NSSCONF_LAST,
+}; /* enum dns_nssconf_keyword */
+
+static enum dns_nssconf_keyword dns_nssconf_keyword(const char *word) {
+	static const char *list[] = {
+		[DNS_NSSCONF_HOSTS]    = "hosts",
+		[DNS_NSSCONF_SUCCESS]  = "success",
+		[DNS_NSSCONF_NOTFOUND] = "notfound",
+		[DNS_NSSCONF_UNAVAIL]  = "unavail",
+		[DNS_NSSCONF_TRYAGAIN] = "tryagain",
+		[DNS_NSSCONF_CONTINUE] = "continue",
+		[DNS_NSSCONF_RETURN]   = "return",
+		[DNS_NSSCONF_FILES]    = "files",
+		[DNS_NSSCONF_DNS]      = "dns",
+		[DNS_NSSCONF_MDNS]     = "mdns",
+	};
+	unsigned i;
+
+	for (i = 1; i < lengthof(list); i++) {
+		if (list[i] && 0 == strcasecmp(list[i], word))
+			return i;
+	}
+
+	return DNS_NSSCONF_INVALID;
+} /* dns_nssconf_keyword() */
+
+
+static enum dns_nssconf_keyword dns_nssconf_c2k(int ch) {
+	static const char map[] = {
+		['S'] = DNS_NSSCONF_SUCCESS,
+		['N'] = DNS_NSSCONF_NOTFOUND,
+		['U'] = DNS_NSSCONF_UNAVAIL,
+		['T'] = DNS_NSSCONF_TRYAGAIN,
+		['C'] = DNS_NSSCONF_CONTINUE,
+		['R'] = DNS_NSSCONF_RETURN,
+		['f'] = DNS_NSSCONF_FILES,
+		['F'] = DNS_NSSCONF_FILES,
+		['d'] = DNS_NSSCONF_DNS,
+		['D'] = DNS_NSSCONF_DNS,
+		['b'] = DNS_NSSCONF_DNS,
+		['B'] = DNS_NSSCONF_DNS,
+		['m'] = DNS_NSSCONF_MDNS,
+		['M'] = DNS_NSSCONF_MDNS,
+	};
+
+	return (ch >= 0 && ch < (int)lengthof(map))? map[ch] : DNS_NSSCONF_INVALID;
+} /* dns_nssconf_c2k() */
+
+
+DNS_PRAGMA_PUSH
+DNS_PRAGMA_QUIET
+
+static int dns_nssconf_k2c(int k) {
+	static const char map[DNS_NSSCONF_LAST] = {
+		[DNS_NSSCONF_SUCCESS]  = 'S',
+		[DNS_NSSCONF_NOTFOUND] = 'N',
+		[DNS_NSSCONF_UNAVAIL]  = 'U',
+		[DNS_NSSCONF_TRYAGAIN] = 'T',
+		[DNS_NSSCONF_CONTINUE] = 'C',
+		[DNS_NSSCONF_RETURN]   = 'R',
+		[DNS_NSSCONF_FILES]    = 'f',
+		[DNS_NSSCONF_DNS]      = 'b',
+		[DNS_NSSCONF_MDNS]     = 'm',
+	};
+
+	return (k >= 0 && k < (int)lengthof(map))? (map[k]? map[k] : '?') : '?';
+} /* dns_nssconf_k2c() */
+
+static const char *dns_nssconf_k2s(int k) {
+	static const char *const map[DNS_NSSCONF_LAST] = {
+		[DNS_NSSCONF_SUCCESS]  = "SUCCESS",
+		[DNS_NSSCONF_NOTFOUND] = "NOTFOUND",
+		[DNS_NSSCONF_UNAVAIL]  = "UNAVAIL",
+		[DNS_NSSCONF_TRYAGAIN] = "TRYAGAIN",
+		[DNS_NSSCONF_CONTINUE] = "continue",
+		[DNS_NSSCONF_RETURN]   = "return",
+		[DNS_NSSCONF_FILES]    = "files",
+		[DNS_NSSCONF_DNS]      = "dns",
+		[DNS_NSSCONF_MDNS]     = "mdns",
+	};
+
+	return (k >= 0 && k < (int)lengthof(map))? (map[k]? map[k] : "") : "";
+} /* dns_nssconf_k2s() */
+
+DNS_PRAGMA_POP
+
+
+int dns_nssconf_loadfile(struct dns_resolv_conf *resconf, FILE *fp) {
+	enum dns_nssconf_keyword source, status, action;
+	char lookup[sizeof resconf->lookup] = "", *lp;
+	struct dns_anyconf cf;
+	size_t i;
+	int error;
+
+	while (!feof(fp) && !ferror(fp)) {
+		dns_anyconf_reset(&cf);
+
+		dns_anyconf_skip("%s", fp);
+
+		if (!dns_anyconf_scan(&cf, "%w_", fp, &error))
+			goto nextent;
+
+		if (DNS_NSSCONF_HOSTS != dns_nssconf_keyword(cf.token[0]))
+			goto nextent;
+
+		dns_anyconf_pop(&cf);
+
+		if (!dns_anyconf_skip(": \t", fp))
+			goto nextent;
+
+		*(lp = lookup) = '\0';
+
+		while (dns_anyconf_scan(&cf, "%w_", fp, &error)) {
+			dns_anyconf_skip(" \t", fp);
+
+			if ('[' == dns_anyconf_peek(fp)) {
+				dns_anyconf_skip("[ \t", fp);
+
+				while (dns_anyconf_scan(&cf, "%w_", fp, &error)) {
+					dns_anyconf_skip("= \t", fp);
+					if (!dns_anyconf_scan(&cf, "%w_", fp, &error)) {
+						dns_anyconf_pop(&cf); /* discard status */
+						dns_anyconf_skip("^#;]\n", fp); /* skip to end of criteria */
+						break;
+					}
+					dns_anyconf_skip(" \t", fp);
+				}
+
+				dns_anyconf_skip("] \t", fp);
+			}
+
+			if ((size_t)(endof(lookup) - lp) < cf.count + 1) /* +1 for '\0' */
+				goto nextsrc;
+
+			source = dns_nssconf_keyword(cf.token[0]);
+
+			switch (source) {
+			case DNS_NSSCONF_DNS:
+			case DNS_NSSCONF_MDNS:
+			case DNS_NSSCONF_FILES:
+				*lp++ = dns_nssconf_k2c(source);
+				break;
+			default:
+				goto nextsrc;
+			}
+
+			for (i = 1; i + 1 < cf.count; i += 2) {
+				status = dns_nssconf_keyword(cf.token[i]);
+				action = dns_nssconf_keyword(cf.token[i + 1]);
+
+				switch (status) {
+				case DNS_NSSCONF_SUCCESS:
+				case DNS_NSSCONF_NOTFOUND:
+				case DNS_NSSCONF_UNAVAIL:
+				case DNS_NSSCONF_TRYAGAIN:
+					*lp++ = dns_nssconf_k2c(status);
+					break;
+				default:
+					continue;
+				}
+
+				switch (action) {
+				case DNS_NSSCONF_CONTINUE:
+				case DNS_NSSCONF_RETURN:
+					break;
+				default:
+					action = (status == DNS_NSSCONF_SUCCESS)
+					       ? DNS_NSSCONF_RETURN
+					       : DNS_NSSCONF_CONTINUE;
+					break;
+				}
+
+				*lp++ = dns_nssconf_k2c(action);
+			}
+nextsrc:
+			*lp = '\0';
+			dns_anyconf_reset(&cf);
+		}
+nextent:
+		dns_anyconf_skip("^\n", fp);
+	}
+
+	if (*lookup)
+		strncpy(resconf->lookup, lookup, sizeof resconf->lookup);
+
+	return 0;
+} /* dns_nssconf_loadfile() */
+
+
+int dns_nssconf_loadpath(struct dns_resolv_conf *resconf, const char *path) {
+	FILE *fp;
+	int error;
+
+	if (!(fp = dns_fopen(path, "rt", &error)))
+		return error;
+
+	error = dns_nssconf_loadfile(resconf, fp);
+
+	fclose(fp);
+
+	return error;
+} /* dns_nssconf_loadpath() */
+
+
+struct dns_nssconf_source {
+	enum dns_nssconf_keyword source, success, notfound, unavail, tryagain;
+}; /* struct dns_nssconf_source */
+
+typedef unsigned dns_nssconf_i;
+
+static inline int dns_nssconf_peek(const struct dns_resolv_conf *resconf, dns_nssconf_i state) {
+	return (state < lengthof(resconf->lookup) && resconf->lookup[state])? resconf->lookup[state] : 0;
+} /* dns_nssconf_peek() */
+
+static _Bool dns_nssconf_next(struct dns_nssconf_source *src, const struct dns_resolv_conf *resconf, dns_nssconf_i *state) {
+	int source, status, action;
+
+	src->source = DNS_NSSCONF_INVALID;
+	src->success = DNS_NSSCONF_RETURN;
+	src->notfound = DNS_NSSCONF_CONTINUE;
+	src->unavail = DNS_NSSCONF_CONTINUE;
+	src->tryagain = DNS_NSSCONF_CONTINUE;
+
+	while ((source = dns_nssconf_peek(resconf, *state))) {
+		source = dns_nssconf_c2k(source);
+		++*state;
+
+		switch (source) {
+		case DNS_NSSCONF_FILES:
+		case DNS_NSSCONF_DNS:
+		case DNS_NSSCONF_MDNS:
+			src->source = source;
+			break;
+		default:
+			continue;
+		}
+
+		while ((status = dns_nssconf_peek(resconf, *state)) && (action = dns_nssconf_peek(resconf, *state + 1))) {
+			status = dns_nssconf_c2k(status);
+			action = dns_nssconf_c2k(action);
+
+			switch (action) {
+			case DNS_NSSCONF_RETURN:
+			case DNS_NSSCONF_CONTINUE:
+				break;
+			default:
+				goto done;
+			}
+
+			switch (status) {
+			case DNS_NSSCONF_SUCCESS:
+				src->success = action;
+				break;
+			case DNS_NSSCONF_NOTFOUND:
+				src->notfound = action;
+				break;
+			case DNS_NSSCONF_UNAVAIL:
+				src->unavail = action;
+				break;
+			case DNS_NSSCONF_TRYAGAIN:
+				src->tryagain = action;
+				break;
+			default:
+				goto done;
+			}
+
+			*state += 2;
+		}
+
+		break;
+	}
+done:
+	return src->source != DNS_NSSCONF_INVALID;
+} /* dns_nssconf_next() */
+
+
+static int dns_nssconf_dump_status(int status, int action, unsigned *count, FILE *fp) {
+	switch (status) {
+	case DNS_NSSCONF_SUCCESS:
+		if (action == DNS_NSSCONF_RETURN)
+			return 0;
+		break;
+	default:
+		if (action == DNS_NSSCONF_CONTINUE)
+			return 0;
+		break;
+	}
+
+	fputc(' ', fp);
+
+	if (!*count)
+		fputc('[', fp);
+
+	fprintf(fp, "%s=%s", dns_nssconf_k2s(status), dns_nssconf_k2s(action));
+
+	++*count;
+
+	return 0;
+} /* dns_nssconf_dump_status() */
+
+
+int dns_nssconf_dump(struct dns_resolv_conf *resconf, FILE *fp) {
+	struct dns_nssconf_source src;
+	dns_nssconf_i i = 0;
+
+	fputs("hosts:", fp);
+
+	while (dns_nssconf_next(&src, resconf, &i)) {
+		unsigned n = 0;
+
+		fprintf(fp, " %s", dns_nssconf_k2s(src.source));
+
+		dns_nssconf_dump_status(DNS_NSSCONF_SUCCESS, src.success, &n, fp);
+		dns_nssconf_dump_status(DNS_NSSCONF_NOTFOUND, src.notfound, &n, fp);
+		dns_nssconf_dump_status(DNS_NSSCONF_UNAVAIL, src.unavail, &n, fp);
+		dns_nssconf_dump_status(DNS_NSSCONF_TRYAGAIN, src.tryagain, &n, fp);
+
+		if (n)
+			fputc(']', fp);
+	}
+
+	fputc('\n', fp);
+
+	return 0;
+} /* dns_nssconf_dump() */
+
+
+int dns_resconf_setiface(struct dns_resolv_conf *resconf, const char *addr, unsigned short port) {
+	int af = (strchr(addr, ':'))? AF_INET6 : AF_INET;
+	int error;
+
+	if ((error = dns_pton(af, addr, dns_sa_addr(af, &resconf->iface, NULL))))
+		return error;
+
+	*dns_sa_port(af, &resconf->iface)	= htons(port);
+	resconf->iface.ss_family		= af;
+
+	return 0;
+} /* dns_resconf_setiface() */
+
+
+#define DNS_SM_RESTORE \
+	do { \
+		pc = 0xff & (*state >> 0); \
+		srchi = 0xff & (*state >> 8); \
+		ndots = 0xff & (*state >> 16); \
+	} while (0)
+
+#define DNS_SM_SAVE \
+	do { \
+		*state = ((0xff & pc) << 0) \
+		       | ((0xff & srchi) << 8) \
+		       | ((0xff & ndots) << 16); \
+	} while (0)
+
+size_t dns_resconf_search(void *dst, size_t lim, const void *qname, size_t qlen, struct dns_resolv_conf *resconf, dns_resconf_i_t *state) {
+	unsigned pc, srchi, ndots, len;
+
+	DNS_SM_ENTER;
+
+	/* if FQDN then return as-is and finish */
+	if (dns_d_isanchored(qname, qlen)) {
+		len = dns_d_anchor(dst, lim, qname, qlen);
+		DNS_SM_YIELD(len);
+		DNS_SM_EXIT;
+	}
+
+	ndots = dns_d_ndots(qname, qlen);
+
+	if (ndots >= resconf->options.ndots) {
+		len = dns_d_anchor(dst, lim, qname, qlen);
+		DNS_SM_YIELD(len);
+	}
+
+	while (srchi < lengthof(resconf->search) && resconf->search[srchi][0]) {
+		struct dns_buf buf = DNS_B_INTO(dst, lim);
+		const char *dn = resconf->search[srchi++];
+
+		dns_b_put(&buf, qname, qlen);
+		dns_b_putc(&buf, '.');
+		dns_b_puts(&buf, dn);
+		if (!dns_d_isanchored(dn, strlen(dn)))
+			dns_b_putc(&buf, '.');
+		len = dns_b_strllen(&buf);
+		DNS_SM_YIELD(len);
+	}
+
+	if (ndots < resconf->options.ndots) {
+		len = dns_d_anchor(dst, lim, qname, qlen);
+		DNS_SM_YIELD(len);
+	}
+
+	DNS_SM_LEAVE;
+
+	return dns_strlcpy(dst, "", lim);
+} /* dns_resconf_search() */
+
+#undef DNS_SM_SAVE
+#undef DNS_SM_RESTORE
+
+
+int dns_resconf_dump(struct dns_resolv_conf *resconf, FILE *fp) {
+	unsigned i;
+	int af;
+
+	for (i = 0; i < lengthof(resconf->nameserver) && (af = resconf->nameserver[i].ss_family) != AF_UNSPEC; i++) {
+		char addr[INET6_ADDRSTRLEN + 1]	= "[INVALID]";
+		unsigned short port;
+
+		dns_inet_ntop(af, dns_sa_addr(af, &resconf->nameserver[i], NULL), addr, sizeof addr);
+		port = ntohs(*dns_sa_port(af, &resconf->nameserver[i]));
+
+		if (port == 53)
+			fprintf(fp, "nameserver %s\n", addr);
+		else
+			fprintf(fp, "nameserver [%s]:%hu\n", addr, port);
+	}
+
+
+	fprintf(fp, "search");
+
+	for (i = 0; i < lengthof(resconf->search) && resconf->search[i][0]; i++)
+		fprintf(fp, " %s", resconf->search[i]);
+
+	fputc('\n', fp);
+
+
+	fputs("; ", fp);
+	dns_nssconf_dump(resconf, fp);
+
+	fprintf(fp, "lookup");
+
+	for (i = 0; i < lengthof(resconf->lookup) && resconf->lookup[i]; i++) {
+		switch (resconf->lookup[i]) {
+		case 'b':
+			fprintf(fp, " bind"); break;
+		case 'f':
+			fprintf(fp, " file"); break;
+		case 'c':
+			fprintf(fp, " cache"); break;
+		}
+	}
+
+	fputc('\n', fp);
+
+
+	fprintf(fp, "options ndots:%u timeout:%u attempts:%u", resconf->options.ndots, resconf->options.timeout, resconf->options.attempts);
+
+	if (resconf->options.edns0)
+		fprintf(fp, " edns0");
+	if (resconf->options.rotate)
+		fprintf(fp, " rotate");
+	if (resconf->options.recurse)
+		fprintf(fp, " recurse");
+	if (resconf->options.smart)
+		fprintf(fp, " smart");
+
+	switch (resconf->options.tcp) {
+	case DNS_RESCONF_TCP_ENABLE:
+		break;
+	case DNS_RESCONF_TCP_ONLY:
+		fprintf(fp, " tcp");
+		break;
+	case DNS_RESCONF_TCP_SOCKS:
+		fprintf(fp, " tcp:socks");
+		break;
+	case DNS_RESCONF_TCP_DISABLE:
+		fprintf(fp, " tcp:disable");
+		break;
+	}
+
+	fputc('\n', fp);
+
+
+	if ((af = resconf->iface.ss_family) != AF_UNSPEC) {
+		char addr[INET6_ADDRSTRLEN + 1]	= "[INVALID]";
+
+		dns_inet_ntop(af, dns_sa_addr(af, &resconf->iface, NULL), addr, sizeof addr);
+
+		fprintf(fp, "interface %s %hu\n", addr, ntohs(*dns_sa_port(af, &resconf->iface)));
+	}
+
+	return 0;
+} /* dns_resconf_dump() */
+
+
+/*
+ * H I N T  S E R V E R  R O U T I N E S
+ *
+ * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
+
+struct dns_hints_soa {
+	unsigned char zone[DNS_D_MAXNAME + 1];
+
+	struct {
+		struct sockaddr_storage ss;
+		unsigned priority;
+	} addrs[16];
+
+	unsigned count;
+
+	struct dns_hints_soa *next;
+}; /* struct dns_hints_soa */
+
+
+struct dns_hints {
+	dns_atomic_t refcount;
+
+	struct dns_hints_soa *head;
+}; /* struct dns_hints */
+
+
+struct dns_hints *dns_hints_open(struct dns_resolv_conf *resconf, int *error) {
+	static const struct dns_hints H_initializer;
+	struct dns_hints *H;
+
+	(void)resconf;
+
+	if (!(H = malloc(sizeof *H)))
+		goto syerr;
+
+	*H	= H_initializer;
+
+	dns_hints_acquire(H);
+
+	return H;
+syerr:
+	*error	= dns_syerr();
+
+	free(H);
+
+	return 0;
+} /* dns_hints_open() */
+
+
+void dns_hints_close(struct dns_hints *H) {
+	struct dns_hints_soa *soa, *nxt;
+
+	if (!H || 1 != dns_hints_release(H))
+		return /* void */;
+
+	for (soa = H->head; soa; soa = nxt) {
+		nxt	= soa->next;
+
+		free(soa);
+	}
+
+	free(H);
+
+	return /* void */;
+} /* dns_hints_close() */
+
+
+dns_refcount_t dns_hints_acquire(struct dns_hints *H) {
+	return dns_atomic_fetch_add(&H->refcount);
+} /* dns_hints_acquire() */
+
+
+dns_refcount_t dns_hints_release(struct dns_hints *H) {
+	return dns_atomic_fetch_sub(&H->refcount);
+} /* dns_hints_release() */
+
+
+struct dns_hints *dns_hints_mortal(struct dns_hints *hints) {
+	if (hints)
+		dns_hints_release(hints);
+
+	return hints;
+} /* dns_hints_mortal() */
+
+
+struct dns_hints *dns_hints_local(struct dns_resolv_conf *resconf, int *error_) {
+	struct dns_hints *hints		= 0;
+	int error;
+
+	if (resconf)
+		dns_resconf_acquire(resconf);
+	else if (!(resconf = dns_resconf_local(&error)))
+		goto error;
+
+	if (!(hints = dns_hints_open(resconf, &error)))
+		goto error;
+
+	error	= 0;
+
+	if (0 == dns_hints_insert_resconf(hints, ".", resconf, &error) && error)
+		goto error;
+
+	dns_resconf_close(resconf);
+
+	return hints;
+error:
+	*error_	= error;
+
+	dns_resconf_close(resconf);
+	dns_hints_close(hints);
+
+	return 0;
+} /* dns_hints_local() */
+
+
+struct dns_hints *dns_hints_root(struct dns_resolv_conf *resconf, int *error_) {
+	static const struct {
+		int af;
+		char addr[INET6_ADDRSTRLEN];
+	} root_hints[] = {
+		{ AF_INET,	"198.41.0.4"		},	/* A.ROOT-SERVERS.NET. */
+		{ AF_INET6,	"2001:503:ba3e::2:30"	},	/* A.ROOT-SERVERS.NET. */
+		{ AF_INET,	"192.228.79.201"	},	/* B.ROOT-SERVERS.NET. */
+		{ AF_INET6,	"2001:500:84::b"	},	/* B.ROOT-SERVERS.NET. */
+		{ AF_INET,	"192.33.4.12"		},	/* C.ROOT-SERVERS.NET. */
+		{ AF_INET6,	"2001:500:2::c"		},	/* C.ROOT-SERVERS.NET. */
+		{ AF_INET,	"199.7.91.13"		},	/* D.ROOT-SERVERS.NET. */
+		{ AF_INET6,	"2001:500:2d::d"	},	/* D.ROOT-SERVERS.NET. */
+		{ AF_INET,	"192.203.230.10"	},	/* E.ROOT-SERVERS.NET. */
+		{ AF_INET,	"192.5.5.241"		},	/* F.ROOT-SERVERS.NET. */
+		{ AF_INET6,	"2001:500:2f::f"	},	/* F.ROOT-SERVERS.NET. */
+		{ AF_INET,	"192.112.36.4"		},	/* G.ROOT-SERVERS.NET. */
+		{ AF_INET,	"128.63.2.53"		},	/* H.ROOT-SERVERS.NET. */
+		{ AF_INET6,	"2001:500:1::803f:235"	},	/* H.ROOT-SERVERS.NET. */
+		{ AF_INET,	"192.36.148.17"		},	/* I.ROOT-SERVERS.NET. */
+		{ AF_INET6,	"2001:7FE::53"		},	/* I.ROOT-SERVERS.NET. */
+		{ AF_INET,	"192.58.128.30"		},	/* J.ROOT-SERVERS.NET. */
+		{ AF_INET6,	"2001:503:c27::2:30"	},	/* J.ROOT-SERVERS.NET. */
+		{ AF_INET,	"193.0.14.129"		},	/* K.ROOT-SERVERS.NET. */
+		{ AF_INET6,	"2001:7FD::1"		},	/* K.ROOT-SERVERS.NET. */
+		{ AF_INET,	"199.7.83.42"		},	/* L.ROOT-SERVERS.NET. */
+		{ AF_INET6,	"2001:500:3::42"	},	/* L.ROOT-SERVERS.NET. */
+		{ AF_INET,	"202.12.27.33"		},	/* M.ROOT-SERVERS.NET. */
+		{ AF_INET6,	"2001:DC3::35"		},	/* M.ROOT-SERVERS.NET. */
+	};
+	struct dns_hints *hints		= 0;
+	struct sockaddr_storage ss;
+	unsigned i;
+	int error, af;
+
+	if (!(hints = dns_hints_open(resconf, &error)))
+		goto error;
+
+	for (i = 0; i < lengthof(root_hints); i++) {
+		af	= root_hints[i].af;
+
+		if ((error = dns_pton(af, root_hints[i].addr, dns_sa_addr(af, &ss, NULL))))
+			goto error;
+
+		*dns_sa_port(af, &ss)	= htons(53);
+		ss.ss_family		= af;
+
+		if ((error = dns_hints_insert(hints, ".", (struct sockaddr *)&ss, 1)))
+			goto error;
+	}
+
+	return hints;
+error:
+	*error_	= error;
+
+	dns_hints_close(hints);
+
+	return 0;
+} /* dns_hints_root() */
+
+
+static struct dns_hints_soa *dns_hints_fetch(struct dns_hints *H, const char *zone) {
+	struct dns_hints_soa *soa;
+
+	for (soa = H->head; soa; soa = soa->next) {
+		if (0 == strcasecmp(zone, (char *)soa->zone))
+			return soa;
+	}
+
+	return 0;
+} /* dns_hints_fetch() */
+
+
+int dns_hints_insert(struct dns_hints *H, const char *zone, const struct sockaddr *sa, unsigned priority) {
+	static const struct dns_hints_soa soa_initializer;
+	struct dns_hints_soa *soa;
+	unsigned i;
+
+	if (!(soa = dns_hints_fetch(H, zone))) {
+		if (!(soa = malloc(sizeof *soa)))
+			return dns_syerr();
+		*soa = soa_initializer;
+		dns_strlcpy((char *)soa->zone, zone, sizeof soa->zone);
+
+		soa->next = H->head;
+		H->head = soa;
+	}
+
+	i = soa->count % lengthof(soa->addrs);
+
+	memcpy(&soa->addrs[i].ss, sa, dns_sa_len(sa));
+
+	soa->addrs[i].priority = DNS_PP_MAX(1, priority);
+
+	if (soa->count < lengthof(soa->addrs))
+		soa->count++;
+
+	return 0;
+} /* dns_hints_insert() */
+
+
+static _Bool dns_hints_isinaddr_any(const void *sa) {
+	struct in_addr *addr;
+
+	if (dns_sa_family(sa) != AF_INET)
+		return 0;
+
+	addr = dns_sa_addr(AF_INET, sa, NULL);
+	return addr->s_addr == htonl(INADDR_ANY);
+}
+
+unsigned dns_hints_insert_resconf(struct dns_hints *H, const char *zone, const struct dns_resolv_conf *resconf, int *error_) {
+	unsigned i, n, p;
+	int error;
+
+	for (i = 0, n = 0, p = 1; i < lengthof(resconf->nameserver) && resconf->nameserver[i].ss_family != AF_UNSPEC; i++, n++) {
+		union { struct sockaddr_in sin; } tmp;
+		struct sockaddr *ns;
+
+		/*
+		 * dns_resconf_open initializes nameserver[0] to INADDR_ANY.
+		 *
+		 * Traditionally the semantics of 0.0.0.0 meant the default
+		 * interface, which evolved to mean the loopback interface.
+		 * See comment block preceding resolv/res_init.c:res_init in
+		 * glibc 2.23. As of 2.23, glibc no longer translates
+		 * 0.0.0.0 despite the code comment, but it does default to
+		 * 127.0.0.1 when no nameservers are present.
+		 *
+		 * BIND9 as of 9.10.3 still translates 0.0.0.0 to 127.0.0.1.
+		 * See lib/lwres/lwconfig.c:lwres_create_addr and the
+		 * convert_zero flag. 127.0.0.1 is also the default when no
+		 * nameservers are present.
+		 */
+		if (dns_hints_isinaddr_any(&resconf->nameserver[i])) {
+			memcpy(&tmp.sin, &resconf->nameserver[i], sizeof tmp.sin);
+			tmp.sin.sin_addr.s_addr = htonl(INADDR_LOOPBACK);
+			ns = (struct sockaddr *)&tmp.sin;
+		} else {
+			ns = (struct sockaddr *)&resconf->nameserver[i];
+		}
+
+		if ((error = dns_hints_insert(H, zone, ns, p)))
+			goto error;
+
+		p += !resconf->options.rotate;
+	}
+
+	return n;
+error:
+	*error_ = error;
+
+	return n;
+} /* dns_hints_insert_resconf() */
+
+
+static int dns_hints_i_cmp(unsigned a, unsigned b, struct dns_hints_i *i, struct dns_hints_soa *soa) {
+	int cmp;
+
+	if ((cmp = soa->addrs[a].priority - soa->addrs[b].priority))
+		return cmp;
+
+	return dns_k_shuffle16(a, i->state.seed) - dns_k_shuffle16(b, i->state.seed);
+} /* dns_hints_i_cmp() */
+
+
+static unsigned dns_hints_i_start(struct dns_hints_i *i, struct dns_hints_soa *soa) {
+	unsigned p0, p;
+
+	p0	= 0;
+
+	for (p = 1; p < soa->count; p++) {
+		if (dns_hints_i_cmp(p, p0, i, soa) < 0)
+			p0	= p;
+	}
+
+	return p0;
+} /* dns_hints_i_start() */
+
+
+static unsigned dns_hints_i_skip(unsigned p0, struct dns_hints_i *i, struct dns_hints_soa *soa) {
+	unsigned pZ, p;
+
+	for (pZ = 0; pZ < soa->count; pZ++) {
+		if (dns_hints_i_cmp(pZ, p0, i, soa) > 0)
+			goto cont;
+	}
+
+	return soa->count;
+cont:
+	for (p = pZ + 1; p < soa->count; p++) {
+		if (dns_hints_i_cmp(p, p0, i, soa) <= 0)
+			continue;
+
+		if (dns_hints_i_cmp(p, pZ, i, soa) >= 0)
+			continue;
+
+		pZ	= p;
+	}
+
+
+	return pZ;
+} /* dns_hints_i_skip() */
+
+
+static struct dns_hints_i *dns_hints_i_init(struct dns_hints_i *i, struct dns_hints *hints) {
+	static const struct dns_hints_i i_initializer;
+	struct dns_hints_soa *soa;
+
+	i->state	= i_initializer.state;
+
+	do {
+		i->state.seed	= dns_random();
+	} while (0 == i->state.seed);
+
+	if ((soa = dns_hints_fetch(hints, i->zone))) {
+		i->state.next	= dns_hints_i_start(i, soa);
+	}
+
+	return i;
+} /* dns_hints_i_init() */
+
+
+unsigned dns_hints_grep(struct sockaddr **sa, socklen_t *sa_len, unsigned lim, struct dns_hints_i *i, struct dns_hints *H) {
+	struct dns_hints_soa *soa;
+	unsigned n;
+
+	if (!(soa = dns_hints_fetch(H, i->zone)))
+		return 0;
+
+	n	= 0;
+
+	while (i->state.next < soa->count && n < lim) {
+		*sa	= (struct sockaddr *)&soa->addrs[i->state.next].ss;
+		*sa_len	= dns_sa_len(*sa);
+
+		sa++;
+		sa_len++;
+		n++;
+
+		i->state.next	= dns_hints_i_skip(i->state.next, i, soa);
+	}
+
+	return n;
+} /* dns_hints_grep() */
+
+
+struct dns_packet *dns_hints_query(struct dns_hints *hints, struct dns_packet *Q, int *error_) {
+	struct dns_packet *A, *P;
+	struct dns_rr rr;
+	char zone[DNS_D_MAXNAME + 1];
+	size_t zlen;
+	struct dns_hints_i i;
+	struct sockaddr *sa;
+	socklen_t slen;
+	int error;
+
+	if (!dns_rr_grep(&rr, 1, dns_rr_i_new(Q, .section = DNS_S_QUESTION), Q, &error))
+		goto error;
+
+	if (!(zlen = dns_d_expand(zone, sizeof zone, rr.dn.p, Q, &error)))
+		goto error;
+	else if (zlen >= sizeof zone)
+		goto toolong;
+
+	P			= dns_p_new(512);
+	dns_header(P)->qr	= 1;
+
+	if ((error = dns_rr_copy(P, &rr, Q)))
+		goto error;
+
+	if ((error = dns_p_push(P, DNS_S_AUTHORITY, ".", strlen("."), DNS_T_NS, DNS_C_IN, 0, "hints.local.")))
+		goto error;
+
+	do {
+		i.zone	= zone;
+
+		dns_hints_i_init(&i, hints);
+
+		while (dns_hints_grep(&sa, &slen, 1, &i, hints)) {
+			int af		= sa->sa_family;
+			int rtype	= (af == AF_INET6)? DNS_T_AAAA : DNS_T_A;
+
+			if ((error = dns_p_push(P, DNS_S_ADDITIONAL, "hints.local.", strlen("hints.local."), rtype, DNS_C_IN, 0, dns_sa_addr(af, sa, NULL))))
+				goto error;
+		}
+	} while ((zlen = dns_d_cleave(zone, sizeof zone, zone, zlen)));
+
+	if (!(A = dns_p_copy(dns_p_make(P->end, &error), P)))
+		goto error;
+
+	return A;
+toolong:
+	error = DNS_EILLEGAL;
+error:
+	*error_	= error;
+
+	return 0;
+} /* dns_hints_query() */
+
+
+/** ugly hack to support specifying ports other than 53 in resolv.conf. */
+static unsigned short dns_hints_port(struct dns_hints *hints, int af, void *addr) {
+	struct dns_hints_soa *soa;
+	void *addrsoa;
+	socklen_t addrlen;
+	unsigned short port;
+	unsigned i;
+
+	for (soa = hints->head; soa; soa = soa->next) {
+		for (i = 0; i < soa->count; i++) {
+			if (af != soa->addrs[i].ss.ss_family)
+				continue;
+
+			if (!(addrsoa = dns_sa_addr(af, &soa->addrs[i].ss, &addrlen)))
+				continue;
+
+			if (memcmp(addr, addrsoa, addrlen))
+				continue;
+
+			port = *dns_sa_port(af, &soa->addrs[i].ss);
+
+			return (port)? port : htons(53);
+		}
+	}
+
+	return htons(53);
+} /* dns_hints_port() */
+
+
+int dns_hints_dump(struct dns_hints *hints, FILE *fp) {
+	struct dns_hints_soa *soa;
+	char addr[INET6_ADDRSTRLEN];
+	unsigned i;
+	int af, error;
+
+	for (soa = hints->head; soa; soa = soa->next) {
+		fprintf(fp, "ZONE \"%s\"\n", soa->zone);
+
+		for (i = 0; i < soa->count; i++) {
+			af = soa->addrs[i].ss.ss_family;
+
+			if ((error = dns_ntop(af, dns_sa_addr(af, &soa->addrs[i].ss, NULL), addr, sizeof addr)))
+				return error;
+
+			fprintf(fp, "\t(%d) [%s]:%hu\n", (int)soa->addrs[i].priority, addr, ntohs(*dns_sa_port(af, &soa->addrs[i].ss)));
+		}
+	}
+
+	return 0;
+} /* dns_hints_dump() */
+
+
+/*
+ * C A C H E  R O U T I N E S
+ *
+ * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
+
+static dns_refcount_t dns_cache_acquire(struct dns_cache *cache) {
+	return dns_atomic_fetch_add(&cache->_.refcount);
+} /* dns_cache_acquire() */
+
+
+static dns_refcount_t dns_cache_release(struct dns_cache *cache) {
+	return dns_atomic_fetch_sub(&cache->_.refcount);
+} /* dns_cache_release() */
+
+
+static struct dns_packet *dns_cache_query(struct dns_packet *query, struct dns_cache *cache, int *error) {
+	(void)query;
+	(void)cache;
+	(void)error;
+
+	return NULL;
+} /* dns_cache_query() */
+
+
+static int dns_cache_submit(struct dns_packet *query, struct dns_cache *cache) {
+	(void)query;
+	(void)cache;
+
+	return 0;
+} /* dns_cache_submit() */
+
+
+static int dns_cache_check(struct dns_cache *cache) {
+	(void)cache;
+
+	return 0;
+} /* dns_cache_check() */
+
+
+static struct dns_packet *dns_cache_fetch(struct dns_cache *cache, int *error) {
+	(void)cache;
+	(void)error;
+
+	return NULL;
+} /* dns_cache_fetch() */
+
+
+static int dns_cache_pollfd(struct dns_cache *cache) {
+	(void)cache;
+
+	return -1;
+} /* dns_cache_pollfd() */
+
+
+static short dns_cache_events(struct dns_cache *cache) {
+	(void)cache;
+
+	return 0;
+} /* dns_cache_events() */
+
+
+static void dns_cache_clear(struct dns_cache *cache) {
+	(void)cache;
+
+	return;
+} /* dns_cache_clear() */
+
+
+struct dns_cache *dns_cache_init(struct dns_cache *cache) {
+	static const struct dns_cache c_init = {
+		.acquire = &dns_cache_acquire,
+		.release = &dns_cache_release,
+		.query   = &dns_cache_query,
+		.submit  = &dns_cache_submit,
+		.check   = &dns_cache_check,
+		.fetch   = &dns_cache_fetch,
+		.pollfd  = &dns_cache_pollfd,
+		.events  = &dns_cache_events,
+		.clear   = &dns_cache_clear,
+		._ = { .refcount = 1, },
+	};
+
+	*cache = c_init;
+
+	return cache;
+} /* dns_cache_init() */
+
+
+void dns_cache_close(struct dns_cache *cache) {
+	if (cache)
+		cache->release(cache);
+} /* dns_cache_close() */
+
+
+/*
+ * S O C K E T  R O U T I N E S
+ *
+ * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
+
+static void dns_socketclose(int *fd, const struct dns_options *opts) {
+	if (opts && opts->closefd.cb)
+		opts->closefd.cb(fd, opts->closefd.arg);
+
+	if (*fd != -1) {
+#if _WIN32
+		closesocket(*fd);
+#else
+		close(*fd);
+#endif
+		*fd	= -1;
+	}
+} /* dns_socketclose() */
+
+
+#ifndef HAVE_IOCTLSOCKET
+#define HAVE_IOCTLSOCKET (_WIN32 || _WIN64)
+#endif
+
+#ifndef HAVE_SOCK_CLOEXEC
+#define HAVE_SOCK_CLOEXEC (defined SOCK_CLOEXEC)
+#endif
+
+#ifndef HAVE_SOCK_NONBLOCK
+#define HAVE_SOCK_NONBLOCK (defined SOCK_NONBLOCK)
+#endif
+
+#define DNS_SO_MAXTRY	7
+
+static int dns_socket(struct sockaddr *local, int type, int *error_) {
+	int fd = -1, flags, error;
+#if defined FIONBIO
+	unsigned long opt;
+#endif
+
+	flags = 0;
+#if HAVE_SOCK_CLOEXEC
+	flags |= SOCK_CLOEXEC;
+#endif
+#if HAVE_SOCK_NONBLOCK
+	flags |= SOCK_NONBLOCK;
+#endif
+	if (-1 == (fd = socket(local->sa_family, type|flags, 0)))
+		goto soerr;
+
+#if defined F_SETFD && !HAVE_SOCK_CLOEXEC
+	if (-1 == fcntl(fd, F_SETFD, 1))
+		goto syerr;
+#endif
+
+#if defined O_NONBLOCK && !HAVE_SOCK_NONBLOCK
+	if (-1 == (flags = fcntl(fd, F_GETFL)))
+		goto syerr;
+	if (-1 == fcntl(fd, F_SETFL, flags | O_NONBLOCK))
+		goto syerr;
+#elif defined FIONBIO && HAVE_IOCTLSOCKET
+	opt = 1;
+	if (0 != ioctlsocket(fd, FIONBIO, &opt))
+		goto soerr;
+#endif
+
+#if defined SO_NOSIGPIPE
+	if (type != SOCK_DGRAM) {
+		if (0 != setsockopt(fd, SOL_SOCKET, SO_NOSIGPIPE, &(int){ 1 }, sizeof (int)))
+			goto soerr;
+	}
+#endif
+
+	if (local->sa_family != AF_INET && local->sa_family != AF_INET6)
+		return fd;
+
+	if (type != SOCK_DGRAM)
+		return fd;
+
+	/*
+	 * FreeBSD, Linux, OpenBSD, OS X, and Solaris use random ports by
+	 * default. Though the ephemeral range is quite small on OS X
+	 * (49152-65535 on 10.10) and Linux (32768-60999 on 4.4.0, Ubuntu
+	 * Xenial). See also RFC 6056.
+	 *
+	 * TODO: Optionally rely on the kernel to select a random port.
+	 */
+	if (*dns_sa_port(local->sa_family, local) == 0) {
+		struct sockaddr_storage tmp;
+		unsigned i, port;
+
+		memcpy(&tmp, local, dns_sa_len(local));
+
+		for (i = 0; i < DNS_SO_MAXTRY; i++) {
+			port = 1025 + (dns_random() % 64510);
+
+			*dns_sa_port(tmp.ss_family, &tmp) = htons(port);
+
+			if (0 == bind(fd, (struct sockaddr *)&tmp, dns_sa_len(&tmp)))
+				return fd;
+		}
+
+		/* NB: continue to next bind statement */
+	}
+
+	if (0 == bind(fd, local, dns_sa_len(local)))
+		return fd;
+
+	/* FALL THROUGH */
+soerr:
+	error = dns_soerr();
+
+	goto error;
+#if (defined F_SETFD && !HAVE_SOCK_CLOEXEC) || (defined O_NONBLOCK && !HAVE_SOCK_NONBLOCK)
+syerr:
+	error = dns_syerr();
+
+	goto error;
+#endif
+error:
+	*error_ = error;
+
+	dns_socketclose(&fd, NULL);
+
+	return -1;
+} /* dns_socket() */
+
+
+enum {
+	DNS_SO_UDP_INIT	= 1,
+	DNS_SO_UDP_CONN,
+	DNS_SO_UDP_SEND,
+	DNS_SO_UDP_RECV,
+	DNS_SO_UDP_DONE,
+
+	DNS_SO_TCP_INIT,
+	DNS_SO_TCP_CONN,
+	DNS_SO_TCP_SEND,
+	DNS_SO_TCP_RECV,
+	DNS_SO_TCP_DONE,
+
+	DNS_SO_SOCKS_INIT,
+	DNS_SO_SOCKS_CONN,
+	DNS_SO_SOCKS_AUTH_SEND,
+	DNS_SO_SOCKS_AUTH_RECV,
+	DNS_SO_SOCKS_REQUEST_SEND,
+	DNS_SO_SOCKS_REQUEST_RECV,
+	DNS_SO_SOCKS_REQUEST_RECV_V6,
+	DNS_SO_SOCKS_HANDSHAKE_DONE,
+};
+
+struct dns_socket {
+	struct dns_options opts;
+
+	int udp;
+	int tcp;
+
+	int *old;
+	unsigned onum, olim;
+
+	int type;
+
+	struct sockaddr_storage local, remote;
+
+	struct dns_k_permutor qids;
+
+	struct dns_stat stat;
+
+	struct dns_trace *trace;
+
+	/*
+	 * NOTE: dns_so_reset() zeroes everything from here down.
+	 */
+	int state;
+
+	unsigned short qid;
+	char qname[DNS_D_MAXNAME + 1];
+	size_t qlen;
+	enum dns_type qtype;
+	enum dns_class qclass;
+
+	struct dns_packet *query;
+	size_t qout;
+
+	/* During a SOCKS handshake the query is temporarily stored
+	 * here.  */
+	struct dns_packet *query_backup;
+
+	struct dns_clock elapsed;
+
+	struct dns_packet *answer;
+	size_t alen, apos;
+}; /* struct dns_socket */
+
+
+/*
+ * NOTE: Actual closure delayed so that kqueue(2) and epoll(2) callers have
+ * a chance to recognize a state change after installing a persistent event
+ * and where sequential descriptors with the same integer value returned
+ * from _pollfd() would be ambiguous. See dns_so_closefds().
+ */
+static int dns_so_closefd(struct dns_socket *so, int *fd) {
+	int error;
+
+	if (*fd == -1)
+		return 0;
+
+	if (so->opts.closefd.cb) {
+		if ((error = so->opts.closefd.cb(fd, so->opts.closefd.arg))) {
+			return error;
+		} else if (*fd == -1)
+			return 0;
+	}
+
+	if (!(so->onum < so->olim)) {
+		unsigned olim = DNS_PP_MAX(4, so->olim * 2);
+		void *old;
+
+		if (!(old = realloc(so->old, sizeof so->old[0] * olim)))
+			return dns_syerr();
+
+		so->old  = old;
+		so->olim = olim;
+	}
+
+	so->old[so->onum++] = *fd;
+	*fd = -1;
+
+	return 0;
+} /* dns_so_closefd() */
+
+
+#define DNS_SO_CLOSE_UDP 0x01
+#define DNS_SO_CLOSE_TCP 0x02
+#define DNS_SO_CLOSE_OLD 0x04
+#define DNS_SO_CLOSE_ALL (DNS_SO_CLOSE_UDP|DNS_SO_CLOSE_TCP|DNS_SO_CLOSE_OLD)
+
+static void dns_so_closefds(struct dns_socket *so, int which) {
+	if (DNS_SO_CLOSE_UDP & which)
+		dns_socketclose(&so->udp, &so->opts);
+	if (DNS_SO_CLOSE_TCP & which)
+		dns_socketclose(&so->tcp, &so->opts);
+	if (DNS_SO_CLOSE_OLD & which) {
+		unsigned i;
+		for (i = 0; i < so->onum; i++)
+			dns_socketclose(&so->old[i], &so->opts);
+		so->onum = 0;
+		free(so->old);
+		so->old  = 0;
+		so->olim = 0;
+	}
+} /* dns_so_closefds() */
+
+
+static void dns_so_destroy(struct dns_socket *);
+
+static struct dns_socket *dns_so_init(struct dns_socket *so, const struct sockaddr *local, int type, const struct dns_options *opts, int *error) {
+	static const struct dns_socket so_initializer = { .opts = DNS_OPTS_INITIALIZER, .udp = -1, .tcp = -1, };
+
+	*so		= so_initializer;
+	so->type	= type;
+
+	if (opts)
+		so->opts = *opts;
+
+	if (local)
+		memcpy(&so->local, local, dns_sa_len(local));
+
+	if (-1 == (so->udp = dns_socket((struct sockaddr *)&so->local, SOCK_DGRAM, error)))
+		goto error;
+
+	dns_k_permutor_init(&so->qids, 1, 65535);
+
+	return so;
+error:
+	dns_so_destroy(so);
+
+	return 0;
+} /* dns_so_init() */
+
+
+struct dns_socket *dns_so_open(const struct sockaddr *local, int type, const struct dns_options *opts, int *error) {
+	struct dns_socket *so;
+
+	if (!(so = malloc(sizeof *so)))
+		goto syerr;
+
+	if (!dns_so_init(so, local, type, opts, error))
+		goto error;
+
+	return so;
+syerr:
+	*error	= dns_syerr();
+error:
+	dns_so_close(so);
+
+	return 0;
+} /* dns_so_open() */
+
+
+static void dns_so_destroy(struct dns_socket *so) {
+	dns_so_reset(so);
+	dns_so_closefds(so, DNS_SO_CLOSE_ALL);
+	dns_trace_close(so->trace);
+} /* dns_so_destroy() */
+
+
+void dns_so_close(struct dns_socket *so) {
+	if (!so)
+		return;
+
+	dns_so_destroy(so);
+
+	free(so);
+} /* dns_so_close() */
+
+
+void dns_so_reset(struct dns_socket *so) {
+	dns_p_setptr(&so->answer, NULL);
+
+	memset(&so->state, '\0', sizeof *so - offsetof(struct dns_socket, state));
+} /* dns_so_reset() */
+
+
+unsigned short dns_so_mkqid(struct dns_socket *so) {
+	return dns_k_permutor_step(&so->qids);
+} /* dns_so_mkqid() */
+
+
+#define DNS_SO_MINBUF	768
+
+static int dns_so_newanswer(struct dns_socket *so, size_t len) {
+	size_t size	= offsetof(struct dns_packet, data) + DNS_PP_MAX(len, DNS_SO_MINBUF);
+	void *p;
+
+	if (!(p = realloc(so->answer, size)))
+		return dns_syerr();
+
+	so->answer	= dns_p_init(p, size);
+
+	return 0;
+} /* dns_so_newanswer() */
+
+
+int dns_so_submit(struct dns_socket *so, struct dns_packet *Q, struct sockaddr *host) {
+	struct dns_rr rr;
+	int error = DNS_EUNKNOWN;
+
+	dns_so_reset(so);
+
+	if ((error = dns_rr_parse(&rr, 12, Q)))
+		goto error;
+
+	if (!(so->qlen = dns_d_expand(so->qname, sizeof so->qname, rr.dn.p, Q, &error)))
+		goto error;
+	/*
+	 * NOTE: Don't bail if expansion is too long; caller may be
+	 * intentionally sending long names. However, we won't be able to
+	 * verify it on return.
+	 */
+
+	so->qtype	= rr.type;
+	so->qclass	= rr.class;
+
+	if ((error = dns_so_newanswer(so, (Q->memo.opt.maxudp)? Q->memo.opt.maxudp : DNS_SO_MINBUF)))
+		goto syerr;
+
+	memcpy(&so->remote, host, dns_sa_len(host));
+
+	so->query	= Q;
+	so->qout	= 0;
+
+	dns_begin(&so->elapsed);
+
+	if (dns_header(so->query)->qid == 0)
+		dns_header(so->query)->qid	= dns_so_mkqid(so);
+
+	so->qid		= dns_header(so->query)->qid;
+	so->state	= (so->opts.socks_host && so->opts.socks_host->ss_family) ? DNS_SO_SOCKS_INIT :
+		(so->type == SOCK_STREAM)? DNS_SO_TCP_INIT : DNS_SO_UDP_INIT;
+
+	so->stat.queries++;
+	dns_trace_so_submit(so->trace, Q, host, 0);
+
+	return 0;
+syerr:
+	error	= dns_syerr();
+error:
+	dns_so_reset(so);
+	dns_trace_so_submit(so->trace, Q, host, error);
+	return error;
+} /* dns_so_submit() */
+
+
+static int dns_so_verify(struct dns_socket *so, struct dns_packet *P) {
+	char qname[DNS_D_MAXNAME + 1];
+	size_t qlen;
+	struct dns_rr rr;
+	int error = -1;
+
+	if (P->end < 12)
+		goto reject;
+
+	if (so->qid != dns_header(P)->qid)
+		goto reject;
+
+	if (!dns_p_count(P, DNS_S_QD))
+		goto reject;
+
+	if (0 != dns_rr_parse(&rr, 12, P))
+		goto reject;
+
+	if (rr.type != so->qtype || rr.class != so->qclass)
+		goto reject;
+
+	if (!(qlen = dns_d_expand(qname, sizeof qname, rr.dn.p, P, &error)))
+		goto error;
+	else if (qlen >= sizeof qname || qlen != so->qlen)
+		goto reject;
+
+	if (0 != strcasecmp(so->qname, qname))
+		goto reject;
+
+	dns_trace_so_verify(so->trace, P, 0);
+
+	return 0;
+reject:
+	error = DNS_EVERIFY;
+error:
+	DNS_SHOW(P, "rejecting packet (%s)", dns_strerror(error));
+	dns_trace_so_verify(so->trace, P, error);
+
+	return error;
+} /* dns_so_verify() */
+
+
+static _Bool dns_so_tcp_keep(struct dns_socket *so) {
+	struct sockaddr_storage remote;
+
+	if (so->tcp == -1)
+		return 0;
+
+	if (0 != getpeername(so->tcp, (struct sockaddr *)&remote, &(socklen_t){ sizeof remote }))
+		return 0;
+
+	return 0 == dns_sa_cmp(&remote, &so->remote);
+} /* dns_so_tcp_keep() */
+
+
+#if defined __clang__
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Warray-bounds"
+#endif
+
+static int dns_so_tcp_send(struct dns_socket *so) {
+	unsigned char *qsrc;
+	size_t qend;
+	int error;
+	size_t n;
+
+	so->query->data[-2] = 0xff & (so->query->end >> 8);
+	so->query->data[-1] = 0xff & (so->query->end >> 0);
+
+	qend = so->query->end + 2;
+
+	while (so->qout < qend) {
+		qsrc = &so->query->data[-2] + so->qout;
+		n = dns_send_nopipe(so->tcp, (void *)qsrc, qend - so->qout, 0, &error);
+		dns_trace_sys_send(so->trace, so->tcp, SOCK_STREAM, qsrc, n, error);
+		if (error)
+			return error;
+		so->qout += n;
+		so->stat.tcp.sent.bytes += n;
+	}
+
+	so->stat.tcp.sent.count++;
+
+	return 0;
+} /* dns_so_tcp_send() */
+
+
+static int dns_so_tcp_recv(struct dns_socket *so) {
+	unsigned char *asrc;
+	size_t aend, alen, n;
+	int error;
+
+	aend = so->alen + 2;
+
+	while (so->apos < aend) {
+		asrc = &so->answer->data[-2];
+
+		n = dns_recv(so->tcp, (void *)&asrc[so->apos], aend - so->apos, 0, &error);
+		dns_trace_sys_recv(so->trace, so->tcp, SOCK_STREAM, &asrc[so->apos], n, error);
+		if (error)
+			return error;
+
+		so->apos += n;
+		so->stat.tcp.rcvd.bytes += n;
+
+		if (so->alen == 0 && so->apos >= 2) {
+			alen = ((0xff & so->answer->data[-2]) << 8)
+			     | ((0xff & so->answer->data[-1]) << 0);
+
+			if ((error = dns_so_newanswer(so, alen)))
+				return error;
+
+			so->alen = alen;
+			aend = alen + 2;
+		}
+	}
+
+	so->answer->end	= so->alen;
+	so->stat.tcp.rcvd.count++;
+
+	return 0;
+} /* dns_so_tcp_recv() */
+
+#if __clang__
+#pragma clang diagnostic pop
+#endif
+
+
+int dns_so_check(struct dns_socket *so) {
+	int error;
+	size_t n;
+
+	/* XXX */
+	unsigned char *buffer;
+	int method;
+
+retry:
+	switch (so->state) {
+	case DNS_SO_UDP_INIT:
+		so->state++;
+	case DNS_SO_UDP_CONN:
+		error = dns_connect(so->udp, (struct sockaddr *)&so->remote, dns_sa_len(&so->remote));
+		dns_trace_sys_connect(so->trace, so->udp, SOCK_DGRAM, (struct sockaddr *)&so->remote, error);
+		if (error)
+			goto error;
+
+		so->state++;
+	case DNS_SO_UDP_SEND:
+		n = dns_send(so->udp, (void *)so->query->data, so->query->end, 0, &error);
+		dns_trace_sys_send(so->trace, so->udp, SOCK_DGRAM, so->query->data, n, error);
+		if (error)
+			goto error;
+
+		so->stat.udp.sent.bytes += n;
+		so->stat.udp.sent.count++;
+
+		so->state++;
+	case DNS_SO_UDP_RECV:
+		n = dns_recv(so->udp, (void *)so->answer->data, so->answer->size, 0, &error);
+		dns_trace_sys_recv(so->trace, so->udp, SOCK_DGRAM, so->answer->data, n, error);
+		if (error)
+			goto error;
+
+		so->answer->end = n;
+		so->stat.udp.rcvd.bytes += n;
+		so->stat.udp.rcvd.count++;
+
+		if ((error = dns_so_verify(so, so->answer)))
+			goto trash;
+
+		so->state++;
+	case DNS_SO_UDP_DONE:
+		if (!dns_header(so->answer)->tc || so->type == SOCK_DGRAM)
+			return 0;
+
+		so->state++;
+	case DNS_SO_TCP_INIT:
+		if (dns_so_tcp_keep(so)) {
+			so->state = DNS_SO_TCP_SEND;
+
+			goto retry;
+		}
+
+		if ((error = dns_so_closefd(so, &so->tcp)))
+			goto error;
+
+		if (-1 == (so->tcp = dns_socket((struct sockaddr *)&so->local, SOCK_STREAM, &error)))
+			goto error;
+
+		so->state++;
+	case DNS_SO_TCP_CONN:
+		error = dns_connect(so->tcp, (struct sockaddr *)&so->remote, dns_sa_len(&so->remote));
+		dns_trace_sys_connect(so->trace, so->tcp, SOCK_STREAM, (struct sockaddr *)&so->remote, error);
+		if (error && error != DNS_EISCONN)
+			goto error;
+
+		so->state++;
+	case DNS_SO_TCP_SEND:
+		if ((error = dns_so_tcp_send(so)))
+			goto error;
+
+		so->state++;
+	case DNS_SO_TCP_RECV:
+		if ((error = dns_so_tcp_recv(so)))
+			goto error;
+
+		so->state++;
+	case DNS_SO_TCP_DONE:
+		/* close unless DNS_RESCONF_TCP_ONLY (see dns_res_tcp2type) */
+		if (so->type != SOCK_STREAM) {
+			if ((error = dns_so_closefd(so, &so->tcp)))
+				goto error;
+		}
+
+		if ((error = dns_so_verify(so, so->answer)))
+			goto error;
+
+		return 0;
+	case DNS_SO_SOCKS_INIT:
+		if ((error = dns_so_closefd(so, &so->tcp)))
+			goto error;
+
+		if (-1 == (so->tcp = dns_socket((struct sockaddr *)&so->local, SOCK_STREAM, &error)))
+			goto error;
+
+		so->state++;
+	case DNS_SO_SOCKS_CONN:
+		error = dns_connect(so->tcp, (struct sockaddr *)so->opts.socks_host, dns_sa_len(so->opts.socks_host));
+		dns_trace_sys_connect(so->trace, so->tcp, SOCK_STREAM, (struct sockaddr *)so->opts.socks_host, error);
+		if (error && error != DNS_EISCONN)
+			goto error;
+
+		/* We need to do a handshake with the SOCKS server,
+		 * but the query is already in the buffer.  Move it
+		 * out of the way.  */
+		dns_p_movptr(&so->query_backup, &so->query);
+
+		/* Create a new buffer for the handshake.  */
+		dns_p_grow(&so->query);
+
+		/* Skip the two octets length field when
+		   transmitting, send three octets.  */
+		so->qout = 2;
+		so->query->end = 3;
+		buffer = so->query->data;
+
+		/* Negotiate method.  */
+		buffer[0] = 5; /* RFC-1928 VER field.  */
+		buffer[1] = 1; /* NMETHODS */
+		if (0 /* XXX */)
+			method = 2;  /* Method: username/password authentication. */
+		else
+			method = 0;  /* Method: No authentication required. */
+		buffer[2] = method;
+
+		so->state++;
+	case DNS_SO_SOCKS_AUTH_SEND:
+		if ((error = dns_so_tcp_send(so)))
+			goto error;
+
+		/* Skip the two length octets, and receive two octets.  */
+		so->apos = 2;
+		so->alen = 2;
+
+		so->state++;
+	case DNS_SO_SOCKS_AUTH_RECV:
+		if ((error = dns_so_tcp_recv(so)))
+			goto error;
+
+		buffer = so->answer->data;
+		method = 0; /* XXX authentication not yet supported */
+		if (buffer[0] != 5 || buffer[1] != method) {
+			/* Socks server returned wrong version or does
+			   not support our requested method.  */
+			error = ENOTSUP; /* Fixme: Is there a better errno? */
+			goto error;
+		}
+
+		/* Skip the two octets length field when
+		   transmitting.  */
+		so->qout = 2;
+		buffer = so->query->data;
+
+		/* Send request details (rfc-1928, 4).  */
+		buffer[0] = 5; /* VER  */
+		buffer[1] = 1; /* CMD = CONNECT  */
+		buffer[2] = 0; /* RSV  */
+		if (so->remote.ss_family == AF_INET6) {
+			struct sockaddr_in6 *addr_in6 = (struct sockaddr_in6 *)&so->remote;
+
+			buffer[3] = 4; /* ATYP = IPv6 */
+			memcpy (buffer+ 4, &addr_in6->sin6_addr.s6_addr, 16); /* DST.ADDR */
+			memcpy (buffer+20, &addr_in6->sin6_port, 2);          /* DST.PORT */
+			so->query->end = 22;
+		} else {
+			struct sockaddr_in *addr_in = (struct sockaddr_in *)&so->remote;
+
+			buffer[3] = 1; /* ATYP = IPv4 */
+			memcpy (buffer+4, &addr_in->sin_addr.s_addr, 4); /* DST.ADDR */
+			memcpy (buffer+8, &addr_in->sin_port, 2);        /* DST.PORT */
+			so->query->end = 10;
+		}
+
+		so->state++;
+	case DNS_SO_SOCKS_REQUEST_SEND:
+		if ((error = dns_so_tcp_send(so)))
+			goto error;
+
+		/* Skip the two length octets, and receive ten octets.
+		 * This is the length of the response assuming a IPv4
+		 * address is used.  */
+		so->apos = 2;
+		so->alen = 10;
+
+		so->state++;
+	case DNS_SO_SOCKS_REQUEST_RECV:
+		if ((error = dns_so_tcp_recv(so)))
+			goto error;
+
+		buffer = so->answer->data;
+		if (buffer[0] != 5 || buffer[2] != 0 ) {
+			/* Socks server returned wrong version or the
+			   reserved field is not zero.  */
+			error = EPROTO;
+			goto error;
+		}
+		if (buffer[1]) {
+			switch (buffer[1]) {
+			case 0x01: /* general SOCKS server failure.  */
+				error = ENETDOWN;
+				break;
+			case 0x02: /* connection not allowed by ruleset.  */
+				error = EACCES;
+				break;
+			case 0x03: /* Network unreachable */
+				error = ENETUNREACH;
+				break;
+			case 0x04: /* Host unreachable */
+				error = EHOSTUNREACH;
+				break;
+			case 0x05: /* Connection refused */
+				error = ECONNREFUSED;
+				break;
+			case 0x06: /* TTL expired */
+				error = ETIMEDOUT;
+				break;
+			case 0x08: /* Address type not supported */
+				error = EPROTONOSUPPORT;
+				break;
+			case 0x07: /* Command not supported */
+			default:
+				error = ENOTSUP; /* Fixme: Is there a better error? */
+				break;
+			}
+			goto error;
+		}
+
+		if (buffer[3] == 1) {
+			/* This was indeed an IPv4 address.  */
+			so->state = DNS_SO_SOCKS_HANDSHAKE_DONE;
+			goto retry;
+		}
+
+		if (buffer[3] != 4) {
+			error = ENOTSUP;
+			goto error;
+		}
+
+		/* ATYP indicates a v6 address.  Skip the two length
+		 * octets, and receive twelve octets.  This accounts
+		 * for the remaining bytes assuming an IPv6 address is
+		 * used.  */
+		so->apos = 2;
+		so->alen = 12;
+
+		so->state++;
+	case DNS_SO_SOCKS_REQUEST_RECV_V6:
+		if ((error = dns_so_tcp_recv(so)))
+			goto error;
+
+		so->state++;
+	case DNS_SO_SOCKS_HANDSHAKE_DONE:
+		/* We have not way to store the actual address used by
+		 * the server.  Then again, we don't really care.  */
+
+		/* Restore the query.  */
+		dns_p_movptr(&so->query, &so->query_backup);
+
+		/* Reset cursors.  */
+		so->qout = 0;
+		so->apos = 0;
+		so->alen = 0;
+
+		/* SOCKS handshake is done.  Proceed with the
+		 * lookup.  */
+		so->state = DNS_SO_TCP_SEND;
+		goto retry;
+	default:
+		error	= DNS_EUNKNOWN;
+
+		goto error;
+	} /* switch() */
+
+trash:
+	DNS_CARP("discarding packet");
+	goto retry;
+error:
+	switch (error) {
+	case DNS_EINTR:
+		goto retry;
+	case DNS_EINPROGRESS:
+		/* FALL THROUGH */
+	case DNS_EALREADY:
+		/* FALL THROUGH */
+#if DNS_EWOULDBLOCK != DNS_EAGAIN
+	case DNS_EWOULDBLOCK:
+		/* FALL THROUGH */
+#endif
+		error	= DNS_EAGAIN;
+
+		break;
+	} /* switch() */
+
+	return error;
+} /* dns_so_check() */
+
+
+struct dns_packet *dns_so_fetch(struct dns_socket *so, int *error) {
+	struct dns_packet *answer;
+
+	switch (so->state) {
+	case DNS_SO_UDP_DONE:
+	case DNS_SO_TCP_DONE:
+		answer		= so->answer;
+		so->answer	= 0;
+		dns_trace_so_fetch(so->trace, answer, 0);
+
+		return answer;
+	default:
+		*error	= DNS_EUNKNOWN;
+		dns_trace_so_fetch(so->trace, NULL, *error);
+
+		return 0;
+	}
+} /* dns_so_fetch() */
+
+
+struct dns_packet *dns_so_query(struct dns_socket *so, struct dns_packet *Q, struct sockaddr *host, int *error_) {
+	struct dns_packet *A;
+	int error;
+
+	if (!so->state) {
+		if ((error = dns_so_submit(so, Q, host)))
+			goto error;
+	}
+
+	if ((error = dns_so_check(so)))
+		goto error;
+
+	if (!(A = dns_so_fetch(so, &error)))
+		goto error;
+
+	dns_so_reset(so);
+
+	return A;
+error:
+	*error_	= error;
+
+	return 0;
+} /* dns_so_query() */
+
+
+time_t dns_so_elapsed(struct dns_socket *so) {
+	return dns_elapsed(&so->elapsed);
+} /* dns_so_elapsed() */
+
+
+void dns_so_clear(struct dns_socket *so) {
+	dns_so_closefds(so, DNS_SO_CLOSE_OLD);
+} /* dns_so_clear() */
+
+
+static int dns_so_events2(struct dns_socket *so, enum dns_events type) {
+	int events = 0;
+
+	switch (so->state) {
+	case DNS_SO_UDP_CONN:
+	case DNS_SO_UDP_SEND:
+		events |= DNS_POLLOUT;
+
+		break;
+	case DNS_SO_UDP_RECV:
+		events |= DNS_POLLIN;
+
+		break;
+	case DNS_SO_TCP_CONN:
+	case DNS_SO_TCP_SEND:
+		events |= DNS_POLLOUT;
+
+		break;
+	case DNS_SO_TCP_RECV:
+		events |= DNS_POLLIN;
+
+		break;
+	} /* switch() */
+
+	switch (type) {
+	case DNS_LIBEVENT:
+		return DNS_POLL2EV(events);
+	default:
+		return events;
+	} /* switch() */
+} /* dns_so_events2() */
+
+
+int dns_so_events(struct dns_socket *so) {
+	return dns_so_events2(so, so->opts.events);
+} /* dns_so_events() */
+
+
+int dns_so_pollfd(struct dns_socket *so) {
+	switch (so->state) {
+	case DNS_SO_UDP_CONN:
+	case DNS_SO_UDP_SEND:
+	case DNS_SO_UDP_RECV:
+		return so->udp;
+	case DNS_SO_TCP_CONN:
+	case DNS_SO_TCP_SEND:
+	case DNS_SO_TCP_RECV:
+		return so->tcp;
+	} /* switch() */
+
+	return -1;
+} /* dns_so_pollfd() */
+
+
+int dns_so_poll(struct dns_socket *so, int timeout) {
+	return dns_poll(dns_so_pollfd(so), dns_so_events2(so, DNS_SYSPOLL), timeout);
+} /* dns_so_poll() */
+
+
+const struct dns_stat *dns_so_stat(struct dns_socket *so) {
+	return &so->stat;
+} /* dns_so_stat() */
+
+
+struct dns_trace *dns_so_trace(struct dns_socket *so) {
+	return so->trace;
+} /* dns_so_trace() */
+
+
+void dns_so_settrace(struct dns_socket *so, struct dns_trace *trace) {
+	struct dns_trace *otrace = so->trace;
+	so->trace = dns_trace_acquire_p(trace);
+	dns_trace_close(otrace);
+} /* dns_so_settrace() */
+
+
+/*
+ * R E S O L V E R  R O U T I N E S
+ *
+ * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
+
+enum dns_res_state {
+	DNS_R_INIT,
+	DNS_R_GLUE,
+	DNS_R_SWITCH,		/* (B)IND, (F)ILE, (C)ACHE */
+
+	DNS_R_FILE,		/* Lookup in local hosts database */
+
+	DNS_R_CACHE,		/* Lookup in application cache */
+	DNS_R_SUBMIT,
+	DNS_R_CHECK,
+	DNS_R_FETCH,
+
+	DNS_R_BIND,		/* Lookup in the network */
+	DNS_R_SEARCH,
+	DNS_R_HINTS,
+	DNS_R_ITERATE,
+	DNS_R_FOREACH_NS,
+	DNS_R_RESOLV0_NS,	/* Prologue: Setup next frame and recurse */
+	DNS_R_RESOLV1_NS,	/* Epilog: Inspect answer */
+	DNS_R_FOREACH_A,
+	DNS_R_QUERY_A,
+	DNS_R_CNAME0_A,
+	DNS_R_CNAME1_A,
+
+	DNS_R_FINISH,
+	DNS_R_SMART0_A,
+	DNS_R_SMART1_A,
+	DNS_R_DONE,
+	DNS_R_SERVFAIL,
+}; /* enum dns_res_state */
+
+
+#define DNS_R_MAXDEPTH	8
+#define DNS_R_ENDFRAME	(DNS_R_MAXDEPTH - 1)
+
+struct dns_resolver {
+	struct dns_socket so;
+
+	struct dns_resolv_conf *resconf;
+	struct dns_hosts *hosts;
+	struct dns_hints *hints;
+	struct dns_cache *cache;
+	struct dns_trace *trace;
+
+	dns_atomic_t refcount;
+
+	/* Reset zeroes everything below here. */
+
+	char qname[DNS_D_MAXNAME + 1];
+	size_t qlen;
+
+	enum dns_type qtype;
+	enum dns_class qclass;
+
+	struct dns_clock elapsed;
+
+	dns_resconf_i_t search;
+
+	struct dns_rr_i smart;
+
+	struct dns_packet *nodata; /* answer if nothing better */
+
+	unsigned sp;
+
+	struct dns_res_frame {
+		enum dns_res_state state;
+
+		int error;
+		int which;	/* (B)IND, (F)ILE; index into resconf->lookup */
+		int qflags;
+
+		unsigned attempts;
+
+		struct dns_packet *query, *answer, *hints;
+
+		struct dns_rr_i hints_i, hints_j;
+		struct dns_rr hints_ns, ans_cname;
+	} stack[DNS_R_MAXDEPTH];
+}; /* struct dns_resolver */
+
+
+static int dns_res_tcp2type(int tcp) {
+	switch (tcp) {
+	case DNS_RESCONF_TCP_ONLY:
+	case DNS_RESCONF_TCP_SOCKS:
+		return SOCK_STREAM;
+	case DNS_RESCONF_TCP_DISABLE:
+		return SOCK_DGRAM;
+	default:
+		return 0;
+	}
+} /* dns_res_tcp2type() */
+
+struct dns_resolver *dns_res_open(struct dns_resolv_conf *resconf, struct dns_hosts *hosts, struct dns_hints *hints, struct dns_cache *cache, const struct dns_options *opts, int *_error) {
+	static const struct dns_resolver R_initializer
+		= { .refcount = 1, };
+	struct dns_resolver *R	= 0;
+	int type, error;
+
+	/*
+	 * Grab ref count early because the caller may have passed us a mortal
+	 * reference, and we want to do the right thing if we return early
+	 * from an error.
+	 */
+	if (resconf)
+		dns_resconf_acquire(resconf);
+	if (hosts)
+		dns_hosts_acquire(hosts);
+	if (hints)
+		dns_hints_acquire(hints);
+	if (cache)
+		dns_cache_acquire(cache);
+
+	/*
+	 * Don't try to load it ourselves because a NULL object might be an
+	 * error from, say, dns_resconf_root(), and loading
+	 * dns_resconf_local() by default would create undesirable surpises.
+	 */
+	if (!resconf || !hosts || !hints) {
+		if (!*_error)
+			*_error = EINVAL;
+		goto _error;
+	}
+
+	if (!(R = malloc(sizeof *R)))
+		goto syerr;
+
+	*R	= R_initializer;
+	type	= dns_res_tcp2type(resconf->options.tcp);
+
+	if (!dns_so_init(&R->so, (struct sockaddr *)&resconf->iface, type, opts, &error))
+		goto error;
+
+	R->resconf	= resconf;
+	R->hosts	= hosts;
+	R->hints	= hints;
+	R->cache	= cache;
+
+	return R;
+syerr:
+	error	= dns_syerr();
+error:
+	*_error	= error;
+_error:
+	dns_res_close(R);
+
+	dns_resconf_close(resconf);
+	dns_hosts_close(hosts);
+	dns_hints_close(hints);
+	dns_cache_close(cache);
+
+	return 0;
+} /* dns_res_open() */
+
+
+struct dns_resolver *dns_res_stub(const struct dns_options *opts, int *error) {
+	struct dns_resolv_conf *resconf	= 0;
+	struct dns_hosts *hosts		= 0;
+	struct dns_hints *hints		= 0;
+	struct dns_resolver *res	= 0;
+
+	if (!(resconf = dns_resconf_local(error)))
+		goto epilog;
+
+	if (!(hosts = dns_hosts_local(error)))
+		goto epilog;
+
+	if (!(hints = dns_hints_local(resconf, error)))
+		goto epilog;
+
+	if (!(res = dns_res_open(resconf, hosts, hints, NULL, opts, error)))
+		goto epilog;
+
+epilog:
+	dns_resconf_close(resconf);
+	dns_hosts_close(hosts);
+	dns_hints_close(hints);
+
+	return res;
+} /* dns_res_stub() */
+
+
+static void dns_res_frame_destroy(struct dns_resolver *R, struct dns_res_frame *frame) {
+	(void)R;
+
+	dns_p_setptr(&frame->query, NULL);
+	dns_p_setptr(&frame->answer, NULL);
+	dns_p_setptr(&frame->hints, NULL);
+} /* dns_res_frame_destroy() */
+
+
+static void dns_res_frame_init(struct dns_resolver *R, struct dns_res_frame *frame) {
+	memset(frame, '\0', sizeof *frame);
+
+	/*
+	 * NB: Can be invoked from dns_res_open, before R->resconf has been
+	 * initialized.
+	 */
+	if (R->resconf) {
+		if (!R->resconf->options.recurse)
+			frame->qflags |= DNS_Q_RD;
+		if (R->resconf->options.edns0)
+			frame->qflags |= DNS_Q_EDNS0;
+	}
+} /* dns_res_frame_init() */
+
+
+static void dns_res_frame_reset(struct dns_resolver *R, struct dns_res_frame *frame) {
+	dns_res_frame_destroy(R, frame);
+	dns_res_frame_init(R, frame);
+} /* dns_res_frame_reset() */
+
+
+static dns_error_t dns_res_frame_prepare(struct dns_resolver *R, struct dns_res_frame *F, const char *qname, enum dns_type qtype, enum dns_class qclass) {
+	struct dns_packet *P = NULL;
+
+	if (!(F < endof(R->stack)))
+		return DNS_EUNKNOWN;
+
+	dns_p_movptr(&P, &F->query);
+	dns_res_frame_reset(R, F);
+	dns_p_movptr(&F->query, &P);
+
+	return dns_q_make(&F->query, qname, qtype, qclass, F->qflags);
+} /* dns_res_frame_prepare() */
+
+
+void dns_res_reset(struct dns_resolver *R) {
+	unsigned i;
+
+	dns_so_reset(&R->so);
+	dns_p_setptr(&R->nodata, NULL);
+
+	for (i = 0; i < lengthof(R->stack); i++)
+		dns_res_frame_destroy(R, &R->stack[i]);
+
+	memset(&R->qname, '\0', sizeof *R - offsetof(struct dns_resolver, qname));
+
+	for (i = 0; i < lengthof(R->stack); i++)
+		dns_res_frame_init(R, &R->stack[i]);
+} /* dns_res_reset() */
+
+
+void dns_res_close(struct dns_resolver *R) {
+	if (!R || 1 < dns_res_release(R))
+		return;
+
+	dns_res_reset(R);
+
+	dns_so_destroy(&R->so);
+
+	dns_hints_close(R->hints);
+	dns_hosts_close(R->hosts);
+	dns_resconf_close(R->resconf);
+	dns_cache_close(R->cache);
+	dns_trace_close(R->trace);
+
+	free(R);
+} /* dns_res_close() */
+
+
+dns_refcount_t dns_res_acquire(struct dns_resolver *R) {
+	return dns_atomic_fetch_add(&R->refcount);
+} /* dns_res_acquire() */
+
+
+dns_refcount_t dns_res_release(struct dns_resolver *R) {
+	return dns_atomic_fetch_sub(&R->refcount);
+} /* dns_res_release() */
+
+
+struct dns_resolver *dns_res_mortal(struct dns_resolver *res) {
+	if (res)
+		dns_res_release(res);
+	return res;
+} /* dns_res_mortal() */
+
+
+static struct dns_packet *dns_res_merge(struct dns_packet *P0, struct dns_packet *P1, int *error_) {
+	size_t bufsiz	= P0->end + P1->end;
+	struct dns_packet *P[3]	= { P0, P1, 0 };
+	struct dns_rr rr[3];
+	int error, copy, i;
+	enum dns_section section;
+
+retry:
+	if (!(P[2] = dns_p_make(bufsiz, &error)))
+		goto error;
+
+	dns_rr_foreach(&rr[0], P[0], .section = DNS_S_QD) {
+		if ((error = dns_rr_copy(P[2], &rr[0], P[0])))
+			goto error;
+	}
+
+	for (section = DNS_S_AN; (DNS_S_ALL & section); section <<= 1) {
+		for (i = 0; i < 2; i++) {
+			dns_rr_foreach(&rr[i], P[i], .section = section) {
+				copy	= 1;
+
+				dns_rr_foreach(&rr[2], P[2], .type = rr[i].type, .section = (DNS_S_ALL & ~DNS_S_QD)) {
+					if (0 == dns_rr_cmp(&rr[i], P[i], &rr[2], P[2])) {
+						copy	= 0;
+
+						break;
+					}
+				}
+
+				if (copy && (error = dns_rr_copy(P[2], &rr[i], P[i]))) {
+					if (error == DNS_ENOBUFS && bufsiz < 65535) {
+						dns_p_setptr(&P[2], NULL);
+
+						bufsiz	= DNS_PP_MAX(65535, bufsiz * 2);
+
+						goto retry;
+					}
+
+					goto error;
+				}
+			} /* foreach(rr) */
+		} /* foreach(packet) */
+	} /* foreach(section) */
+
+	return P[2];
+error:
+	*error_	= error;
+
+	dns_p_free(P[2]);
+
+	return 0;
+} /* dns_res_merge() */
+
+
+static struct dns_packet *dns_res_glue(struct dns_resolver *R, struct dns_packet *Q) {
+	struct dns_packet *P	= dns_p_new(512);
+	char qname[DNS_D_MAXNAME + 1];
+	size_t qlen;
+	enum dns_type qtype;
+	struct dns_rr rr;
+	unsigned sp;
+	int error;
+
+	if (!(qlen = dns_d_expand(qname, sizeof qname, 12, Q, &error))
+	||  qlen >= sizeof qname)
+		return 0;
+
+	if (!(qtype = dns_rr_type(12, Q)))
+		return 0;
+
+	if ((error = dns_p_push(P, DNS_S_QD, qname, strlen(qname), qtype, DNS_C_IN, 0, 0)))
+		return 0;
+
+	for (sp = 0; sp <= R->sp; sp++) {
+		if (!R->stack[sp].answer)
+			continue;
+
+		dns_rr_foreach(&rr, R->stack[sp].answer, .name = qname, .type = qtype, .section = (DNS_S_ALL & ~DNS_S_QD)) {
+			rr.section	= DNS_S_AN;
+
+			if ((error = dns_rr_copy(P, &rr, R->stack[sp].answer)))
+				return 0;
+		}
+	}
+
+	if (dns_p_count(P, DNS_S_AN) > 0)
+		goto copy;
+
+	/* Otherwise, look for a CNAME */
+	for (sp = 0; sp <= R->sp; sp++) {
+		if (!R->stack[sp].answer)
+			continue;
+
+		dns_rr_foreach(&rr, R->stack[sp].answer, .name = qname, .type = DNS_T_CNAME, .section = (DNS_S_ALL & ~DNS_S_QD)) {
+			rr.section	= DNS_S_AN;
+
+			if ((error = dns_rr_copy(P, &rr, R->stack[sp].answer)))
+				return 0;
+		}
+	}
+
+	if (!dns_p_count(P, DNS_S_AN))
+		return 0;
+
+copy:
+	return dns_p_copy(dns_p_make(P->end, &error), P);
+} /* dns_res_glue() */
+
+
+/*
+ * Sort NS records by three criteria:
+ *
+ * 	1) Whether glue is present.
+ * 	2) Whether glue record is original or of recursive lookup.
+ * 	3) Randomly shuffle records which share the above criteria.
+ *
+ * NOTE: Assumes only NS records passed, AND ASSUMES no new NS records will
+ *       be added during an iteration.
+ *
+ * FIXME: Only groks A glue, not AAAA glue.
+ */
+static int dns_res_nameserv_cmp(struct dns_rr *a, struct dns_rr *b, struct dns_rr_i *i, struct dns_packet *P) {
+	_Bool glued[2] = { 0 };
+	struct dns_rr x = { 0 }, y = { 0 };
+	struct dns_ns ns;
+	int cmp, error;
+
+	if (!(error = dns_ns_parse(&ns, a, P)))
+		glued[0] = !!dns_rr_grep(&x, 1, dns_rr_i_new(P, .section = (DNS_S_ALL & ~DNS_S_QD), .name = ns.host, .type = DNS_T_A), P, &error);
+
+	if (!(error = dns_ns_parse(&ns, b, P)))
+		glued[1] = !!dns_rr_grep(&y, 1, dns_rr_i_new(P, .section = (DNS_S_ALL & ~DNS_S_QD), .name = ns.host, .type = DNS_T_A), P, &error);
+
+	if ((cmp = glued[1] - glued[0])) {
+		return cmp;
+	} else if ((cmp = (dns_rr_offset(&y) < i->args[0]) - (dns_rr_offset(&x) < i->args[0]))) {
+		return cmp;
+	} else {
+		return dns_rr_i_shuffle(a, b, i, P);
+	}
+} /* dns_res_nameserv_cmp() */
+
+
+#define dgoto(sp, i)	\
+	do { R->stack[(sp)].state = (i); goto exec; } while (0)
+
+static int dns_res_exec(struct dns_resolver *R) {
+	struct dns_res_frame *F;
+	struct dns_packet *P;
+	union {
+		char host[DNS_D_MAXNAME + 1];
+		char name[DNS_D_MAXNAME + 1];
+		struct dns_ns ns;
+		struct dns_cname cname;
+	} u;
+	size_t len;
+	struct dns_rr rr;
+	int error;
+
+exec:
+
+	F	= &R->stack[R->sp];
+
+	switch (F->state) {
+	case DNS_R_INIT:
+		F->state++;
+	case DNS_R_GLUE:
+		if (R->sp == 0)
+			dgoto(R->sp, DNS_R_SWITCH);
+
+		if (!F->query)
+			goto noquery;
+
+		if (!(F->answer = dns_res_glue(R, F->query)))
+			dgoto(R->sp, DNS_R_SWITCH);
+
+		if (!(len = dns_d_expand(u.name, sizeof u.name, 12, F->query, &error)))
+			goto error;
+		else if (len >= sizeof u.name)
+			goto toolong;
+
+		dns_rr_foreach(&rr, F->answer, .name = u.name, .type = dns_rr_type(12, F->query), .section = DNS_S_AN) {
+			dgoto(R->sp, DNS_R_FINISH);
+		}
+
+		dns_rr_foreach(&rr, F->answer, .name = u.name, .type = DNS_T_CNAME, .section = DNS_S_AN) {
+			F->ans_cname	= rr;
+
+			dgoto(R->sp, DNS_R_CNAME0_A);
+		}
+
+		F->state++;
+	case DNS_R_SWITCH:
+		while (F->which < (int)sizeof R->resconf->lookup && R->resconf->lookup[F->which]) {
+			switch (R->resconf->lookup[F->which++]) {
+			case 'b': case 'B':
+				dgoto(R->sp, DNS_R_BIND);
+			case 'f': case 'F':
+				dgoto(R->sp, DNS_R_FILE);
+			case 'c': case 'C':
+				if (R->cache)
+					dgoto(R->sp, DNS_R_CACHE);
+
+				break;
+			default:
+				break;
+			}
+		}
+
+		/*
+		 * FIXME: Examine more closely whether our logic is correct
+		 * and DNS_R_SERVFAIL is the correct default response.
+		 *
+		 * Case 1: We got here because we never got an answer on the
+		 *   wire. All queries timed-out and we reached maximum
+		 *   attempts count. See DNS_R_FOREACH_NS. In that case
+		 *   DNS_R_SERVFAIL is the correct state, unless we want to
+		 *   return DNS_ETIMEDOUT.
+		 *
+		 * Case 2: We were a stub resolver and got an unsatisfactory
+		 *   answer (empty ANSWER section) which caused us to jump
+		 *   back to DNS_R_SEARCH and ultimately to DNS_R_SWITCH. We
+		 *   return the answer returned from the wire, which we
+		 *   stashed in R->nodata.
+		 *
+		 * Case 3: We reached maximum attempts count as in case #1,
+		 *   but never got an authoritative response which caused us
+		 *   to short-circuit. See end of DNS_R_QUERY_A case. We
+		 *   should probably prepare R->nodata as in case #2.
+		 */
+		if (R->sp == 0 && R->nodata) { /* XXX: can we just return nodata regardless? */
+			dns_p_movptr(&F->answer, &R->nodata);
+			dgoto(R->sp, DNS_R_FINISH);
+		}
+
+		dgoto(R->sp, DNS_R_SERVFAIL);
+	case DNS_R_FILE:
+		if (R->sp > 0) {
+			if (!dns_p_setptr(&F->answer, dns_hosts_query(R->hosts, F->query, &error)))
+				goto error;
+
+			if (dns_p_count(F->answer, DNS_S_AN) > 0)
+				dgoto(R->sp, DNS_R_FINISH);
+
+			dns_p_setptr(&F->answer, NULL);
+		} else {
+			R->search = 0;
+
+			while ((len = dns_resconf_search(u.name, sizeof u.name, R->qname, R->qlen, R->resconf, &R->search))) {
+				if ((error = dns_q_make2(&F->query, u.name, len, R->qtype, R->qclass, F->qflags)))
+					goto error;
+
+				if (!dns_p_setptr(&F->answer, dns_hosts_query(R->hosts, F->query, &error)))
+					goto error;
+
+				if (dns_p_count(F->answer, DNS_S_AN) > 0)
+					dgoto(R->sp, DNS_R_FINISH);
+
+				dns_p_setptr(&F->answer, NULL);
+			}
+		}
+
+		dgoto(R->sp, DNS_R_SWITCH);
+	case DNS_R_CACHE:
+		error = 0;
+
+		if (!F->query && (error = dns_q_make(&F->query, R->qname, R->qtype, R->qclass, F->qflags)))
+			goto error;
+
+		if (dns_p_setptr(&F->answer, R->cache->query(F->query, R->cache, &error))) {
+			if (dns_p_count(F->answer, DNS_S_AN) > 0)
+				dgoto(R->sp, DNS_R_FINISH);
+
+			dns_p_setptr(&F->answer, NULL);
+
+			dgoto(R->sp, DNS_R_SWITCH);
+		} else if (error)
+			goto error;
+
+		F->state++;
+	case DNS_R_SUBMIT:
+		if ((error = R->cache->submit(F->query, R->cache)))
+			goto error;
+
+		F->state++;
+	case DNS_R_CHECK:
+		if ((error = R->cache->check(R->cache)))
+			goto error;
+
+		F->state++;
+	case DNS_R_FETCH:
+		error = 0;
+
+		if (dns_p_setptr(&F->answer, R->cache->fetch(R->cache, &error))) {
+			if (dns_p_count(F->answer, DNS_S_AN) > 0)
+				dgoto(R->sp, DNS_R_FINISH);
+
+			dns_p_setptr(&F->answer, NULL);
+
+			dgoto(R->sp, DNS_R_SWITCH);
+		} else if (error)
+			goto error;
+
+		dgoto(R->sp, DNS_R_SWITCH);
+	case DNS_R_BIND:
+		if (R->sp > 0) {
+			if (!F->query)
+				goto noquery;
+
+			dgoto(R->sp, DNS_R_HINTS);
+		}
+
+		R->search = 0;
+
+		F->state++;
+	case DNS_R_SEARCH:
+		/*
+		 * XXX: We probably should only apply the domain search
+		 * algorithm if R->sp == 0.
+		 */
+		if (!(len = dns_resconf_search(u.name, sizeof u.name, R->qname, R->qlen, R->resconf, &R->search)))
+			dgoto(R->sp, DNS_R_SWITCH);
+
+		if ((error = dns_q_make2(&F->query, u.name, len, R->qtype, R->qclass, F->qflags)))
+			goto error;
+
+		F->state++;
+	case DNS_R_HINTS:
+		if (!dns_p_setptr(&F->hints, dns_hints_query(R->hints, F->query, &error)))
+			goto error;
+
+		F->state++;
+	case DNS_R_ITERATE:
+		dns_rr_i_init(&F->hints_i, F->hints);
+
+		F->hints_i.section	= DNS_S_AUTHORITY;
+		F->hints_i.type		= DNS_T_NS;
+		F->hints_i.sort		= &dns_res_nameserv_cmp;
+		F->hints_i.args[0]	= F->hints->end;
+
+		F->state++;
+	case DNS_R_FOREACH_NS:
+		dns_rr_i_save(&F->hints_i);
+
+		/* Load our next nameserver host. */
+		if (!dns_rr_grep(&F->hints_ns, 1, &F->hints_i, F->hints, &error)) {
+			if (++F->attempts < R->resconf->options.attempts)
+				dgoto(R->sp, DNS_R_ITERATE);
+
+			dgoto(R->sp, DNS_R_SWITCH);
+		}
+
+		dns_rr_i_init(&F->hints_j, F->hints);
+
+		/* Assume there are glue records */
+		dgoto(R->sp, DNS_R_FOREACH_A);
+	case DNS_R_RESOLV0_NS:
+		/* Have we reached our max depth? */
+		if (&F[1] >= endof(R->stack))
+			dgoto(R->sp, DNS_R_FOREACH_NS);
+
+		if ((error = dns_ns_parse(&u.ns, &F->hints_ns, F->hints)))
+			goto error;
+		if ((error = dns_res_frame_prepare(R, &F[1], u.ns.host, DNS_T_A, DNS_C_IN)))
+			goto error;
+
+		F->state++;
+
+		dgoto(++R->sp, DNS_R_INIT);
+	case DNS_R_RESOLV1_NS:
+		if (!(len = dns_d_expand(u.host, sizeof u.host, 12, F[1].query, &error)))
+			goto error;
+		else if (len >= sizeof u.host)
+			goto toolong;
+
+		dns_rr_foreach(&rr, F[1].answer, .name = u.host, .type = DNS_T_A, .section = (DNS_S_ALL & ~DNS_S_QD)) {
+			rr.section	= DNS_S_AR;
+
+			if ((error = dns_rr_copy(F->hints, &rr, F[1].answer)))
+				goto error;
+
+			dns_rr_i_rewind(&F->hints_i);	/* Now there's glue. */
+		}
+
+		dgoto(R->sp, DNS_R_FOREACH_NS);
+	case DNS_R_FOREACH_A: {
+		struct dns_a a;
+		struct sockaddr_in sin;
+
+		/*
+		 * NOTE: Iterator initialized in DNS_R_FOREACH_NS because
+		 * this state is re-entrant, but we need to reset
+		 * .name to a valid pointer each time.
+		 */
+		if ((error = dns_ns_parse(&u.ns, &F->hints_ns, F->hints)))
+			goto error;
+
+		F->hints_j.name		= u.ns.host;
+		F->hints_j.type		= DNS_T_A;
+		F->hints_j.section	= DNS_S_ALL & ~DNS_S_QD;
+
+		if (!dns_rr_grep(&rr, 1, &F->hints_j, F->hints, &error)) {
+			if (!dns_rr_i_count(&F->hints_j))
+				dgoto(R->sp, DNS_R_RESOLV0_NS);
+
+			dgoto(R->sp, DNS_R_FOREACH_NS);
+		}
+
+		if ((error = dns_a_parse(&a, &rr, F->hints)))
+			goto error;
+
+		memset(&sin, '\0', sizeof sin); /* NB: silence valgrind */
+		sin.sin_family	= AF_INET;
+		sin.sin_addr	= a.addr;
+		if (R->sp == 0)
+			sin.sin_port = dns_hints_port(R->hints, AF_INET, &sin.sin_addr);
+		else
+			sin.sin_port = htons(53);
+
+		if (DNS_DEBUG) {
+			char addr[INET_ADDRSTRLEN + 1];
+			dns_a_print(addr, sizeof addr, &a);
+			dns_header(F->query)->qid = dns_so_mkqid(&R->so);
+			DNS_SHOW(F->query, "ASKING: %s/%s @ DEPTH: %u)", u.ns.host, addr, R->sp);
+		}
+
+		dns_trace_setcname(R->trace, u.ns.host, (struct sockaddr *)&sin);
+
+		if ((error = dns_so_submit(&R->so, F->query, (struct sockaddr *)&sin)))
+			goto error;
+
+		F->state++;
+	}
+	case DNS_R_QUERY_A:
+		if (dns_so_elapsed(&R->so) >= dns_resconf_timeout(R->resconf))
+			dgoto(R->sp, DNS_R_FOREACH_A);
+
+		if ((error = dns_so_check(&R->so)))
+			goto error;
+
+		if (!dns_p_setptr(&F->answer, dns_so_fetch(&R->so, &error)))
+			goto error;
+
+		if (DNS_DEBUG) {
+			DNS_SHOW(F->answer, "ANSWER @ DEPTH: %u)", R->sp);
+		}
+
+		if (dns_p_rcode(F->answer) == DNS_RC_FORMERR ||
+		    dns_p_rcode(F->answer) == DNS_RC_NOTIMP ||
+		    dns_p_rcode(F->answer) == DNS_RC_BADVERS) {
+			/* Temporarily disable EDNS0 and try again. */
+			if (F->qflags & DNS_Q_EDNS0) {
+				F->qflags &= ~DNS_Q_EDNS0;
+				if ((error = dns_q_remake(&F->query, F->qflags)))
+					goto error;
+
+				dgoto(R->sp, DNS_R_FOREACH_A);
+			}
+		}
+
+		if ((error = dns_rr_parse(&rr, 12, F->query)))
+			goto error;
+
+		if (!(len = dns_d_expand(u.name, sizeof u.name, rr.dn.p, F->query, &error)))
+			goto error;
+		else if (len >= sizeof u.name)
+			goto toolong;
+
+		dns_rr_foreach(&rr, F->answer, .section = DNS_S_AN, .name = u.name, .type = rr.type) {
+			dgoto(R->sp, DNS_R_FINISH);	/* Found */
+		}
+
+		dns_rr_foreach(&rr, F->answer, .section = DNS_S_AN, .name = u.name, .type = DNS_T_CNAME) {
+			F->ans_cname	= rr;
+
+			dgoto(R->sp, DNS_R_CNAME0_A);
+		}
+
+		/*
+		 * XXX: The condition here should probably check whether
+		 * R->sp == 0, because DNS_R_SEARCH runs regardless of
+		 * options.recurse. See DNS_R_BIND.
+		 */
+		if (!R->resconf->options.recurse) {
+			/* Make first answer our tentative answer */
+			if (!R->nodata)
+				dns_p_movptr(&R->nodata, &F->answer);
+
+			dgoto(R->sp, DNS_R_SEARCH);
+		}
+
+		dns_rr_foreach(&rr, F->answer, .section = DNS_S_NS, .type = DNS_T_NS) {
+			dns_p_movptr(&F->hints, &F->answer);
+
+			dgoto(R->sp, DNS_R_ITERATE);
+		}
+
+		/* XXX: Should this go further up? */
+		if (dns_header(F->answer)->aa)
+			dgoto(R->sp, DNS_R_FINISH);
+
+		/* XXX: Should we copy F->answer to R->nodata? */
+
+		dgoto(R->sp, DNS_R_FOREACH_A);
+	case DNS_R_CNAME0_A:
+		if (&F[1] >= endof(R->stack))
+			dgoto(R->sp, DNS_R_FINISH);
+
+		if ((error = dns_cname_parse(&u.cname, &F->ans_cname, F->answer)))
+			goto error;
+		if ((error = dns_res_frame_prepare(R, &F[1], u.cname.host, dns_rr_type(12, F->query), DNS_C_IN)))
+			goto error;
+
+		F->state++;
+
+		dgoto(++R->sp, DNS_R_INIT);
+	case DNS_R_CNAME1_A:
+		if (!(P = dns_res_merge(F->answer, F[1].answer, &error)))
+			goto error;
+
+		dns_p_setptr(&F->answer, P);
+
+		dgoto(R->sp, DNS_R_FINISH);
+	case DNS_R_FINISH:
+		if (!F->answer)
+			goto noanswer;
+
+		if (!R->resconf->options.smart || R->sp > 0)
+			dgoto(R->sp, DNS_R_DONE);
+
+		R->smart.section	= DNS_S_AN;
+		R->smart.type		= R->qtype;
+
+		dns_rr_i_init(&R->smart, F->answer);
+
+		F->state++;
+	case DNS_R_SMART0_A:
+		if (&F[1] >= endof(R->stack))
+			dgoto(R->sp, DNS_R_DONE);
+
+		while (dns_rr_grep(&rr, 1, &R->smart, F->answer, &error)) {
+			union {
+				struct dns_ns ns;
+				struct dns_mx mx;
+				struct dns_srv srv;
+			} rd;
+			const char *qname;
+			enum dns_type qtype;
+			enum dns_class qclass;
+
+			switch (rr.type) {
+			case DNS_T_NS:
+				if ((error = dns_ns_parse(&rd.ns, &rr, F->answer)))
+					goto error;
+
+				qname	= rd.ns.host;
+				qtype	= DNS_T_A;
+				qclass	= DNS_C_IN;
+
+				break;
+			case DNS_T_MX:
+				if ((error = dns_mx_parse(&rd.mx, &rr, F->answer)))
+					goto error;
+
+				qname	= rd.mx.host;
+				qtype	= DNS_T_A;
+				qclass	= DNS_C_IN;
+
+				break;
+			case DNS_T_SRV:
+				if ((error = dns_srv_parse(&rd.srv, &rr, F->answer)))
+					goto error;
+
+				qname	= rd.srv.target;
+				qtype	= DNS_T_A;
+				qclass	= DNS_C_IN;
+
+				break;
+			default:
+				continue;
+			} /* switch() */
+
+			if ((error = dns_res_frame_prepare(R, &F[1], qname, qtype, qclass)))
+				goto error;
+
+			F->state++;
+
+			dgoto(++R->sp, DNS_R_INIT);
+		} /* while() */
+
+		/*
+		 * NOTE: SMTP specification says to fallback to A record.
+		 *
+		 * XXX: Should we add a mock MX answer?
+		 */
+		if (R->qtype == DNS_T_MX && R->smart.state.count == 0) {
+			if ((error = dns_res_frame_prepare(R, &F[1], R->qname, DNS_T_A, DNS_C_IN)))
+				goto error;
+
+			R->smart.state.count++;
+			F->state++;
+
+			dgoto(++R->sp, DNS_R_INIT);
+		}
+
+		dgoto(R->sp, DNS_R_DONE);
+	case DNS_R_SMART1_A:
+		if (!F[1].answer)
+			goto noanswer;
+
+		/*
+		 * FIXME: For CNAME chains (which are typically illegal in
+		 * this context), we should rewrite the record host name
+		 * to the original smart qname. All the user cares about
+		 * is locating that A/AAAA record.
+		 */
+		dns_rr_foreach(&rr, F[1].answer, .section = DNS_S_AN, .type = DNS_T_A) {
+			rr.section	= DNS_S_AR;
+
+			if (dns_rr_exists(&rr, F[1].answer, F->answer))
+				continue;
+
+			while ((error = dns_rr_copy(F->answer, &rr, F[1].answer))) {
+				if (error != DNS_ENOBUFS)
+					goto error;
+				if ((error = dns_p_grow(&F->answer)))
+					goto error;
+			}
+		}
+
+		dgoto(R->sp, DNS_R_SMART0_A);
+	case DNS_R_DONE:
+		if (!F->answer)
+			goto noanswer;
+
+		if (R->sp > 0)
+			dgoto(--R->sp, F[-1].state);
+
+		break;
+	case DNS_R_SERVFAIL:
+		if (!dns_p_setptr(&F->answer, dns_p_make(DNS_P_QBUFSIZ, &error)))
+			goto error;
+
+		dns_header(F->answer)->qr	= 1;
+		dns_header(F->answer)->rcode	= DNS_RC_SERVFAIL;
+
+		if ((error = dns_p_push(F->answer, DNS_S_QD, R->qname, strlen(R->qname), R->qtype, R->qclass, 0, 0)))
+			goto error;
+
+		dgoto(R->sp, DNS_R_DONE);
+	default:
+		error	= EINVAL;
+
+		goto error;
+	} /* switch () */
+
+	return 0;
+noquery:
+	error = DNS_ENOQUERY;
+
+	goto error;
+noanswer:
+	error = DNS_ENOANSWER;
+
+	goto error;
+toolong:
+	error = DNS_EILLEGAL;
+
+	/* FALL THROUGH */
+error:
+	return error;
+} /* dns_res_exec() */
+
+#undef goto
+
+
+void dns_res_clear(struct dns_resolver *R) {
+	switch (R->stack[R->sp].state) {
+	case DNS_R_CHECK:
+		R->cache->clear(R->cache);
+		break;
+	default:
+		dns_so_clear(&R->so);
+		break;
+	}
+} /* dns_res_clear() */
+
+
+static int dns_res_events2(struct dns_resolver *R, enum dns_events type) {
+	int events;
+
+	switch (R->stack[R->sp].state) {
+	case DNS_R_CHECK:
+		events = R->cache->events(R->cache);
+
+		return (type == DNS_LIBEVENT)? DNS_POLL2EV(events) : events;
+	default:
+		return dns_so_events2(&R->so, type);
+	}
+} /* dns_res_events2() */
+
+
+int dns_res_events(struct dns_resolver *R) {
+	return dns_res_events2(R, R->so.opts.events);
+} /* dns_res_events() */
+
+
+int dns_res_pollfd(struct dns_resolver *R) {
+	switch (R->stack[R->sp].state) {
+	case DNS_R_CHECK:
+		return R->cache->pollfd(R->cache);
+	default:
+		return dns_so_pollfd(&R->so);
+	}
+} /* dns_res_pollfd() */
+
+
+time_t dns_res_timeout(struct dns_resolver *R) {
+	time_t elapsed;
+
+	switch (R->stack[R->sp].state) {
+#if 0
+	case DNS_R_QUERY_AAAA:
+#endif
+	case DNS_R_QUERY_A:
+		elapsed = dns_so_elapsed(&R->so);
+
+		if (elapsed <= dns_resconf_timeout(R->resconf))
+			return R->resconf->options.timeout - elapsed;
+
+		break;
+	default:
+		break;
+	} /* switch() */
+
+	/*
+	 * NOTE: We're not in a pollable state, or the user code hasn't
+	 * called dns_res_check properly. The calling code is probably
+	 * broken. Put them into a slow-burn pattern.
+	 */
+	return 1;
+} /* dns_res_timeout() */
+
+
+time_t dns_res_elapsed(struct dns_resolver *R) {
+	return dns_elapsed(&R->elapsed);
+} /* dns_res_elapsed() */
+
+
+int dns_res_poll(struct dns_resolver *R, int timeout) {
+	return dns_poll(dns_res_pollfd(R), dns_res_events2(R, DNS_SYSPOLL), timeout);
+} /* dns_res_poll() */
+
+
+int dns_res_submit2(struct dns_resolver *R, const char *qname, size_t qlen, enum dns_type qtype, enum dns_class qclass) {
+	dns_res_reset(R);
+
+	/* Don't anchor; that can conflict with searchlist generation. */
+	dns_d_init(R->qname, sizeof R->qname, qname, (R->qlen = qlen), 0);
+
+	R->qtype	= qtype;
+	R->qclass	= qclass;
+
+	dns_begin(&R->elapsed);
+
+	dns_trace_res_submit(R->trace, R->qname, R->qtype, R->qclass, 0);
+
+	return 0;
+} /* dns_res_submit2() */
+
+
+int dns_res_submit(struct dns_resolver *R, const char *qname, enum dns_type qtype, enum dns_class qclass) {
+	return dns_res_submit2(R, qname, strlen(qname), qtype, qclass);
+} /* dns_res_submit() */
+
+
+int dns_res_check(struct dns_resolver *R) {
+	int error;
+
+	if (R->stack[0].state != DNS_R_DONE) {
+		if ((error = dns_res_exec(R)))
+			return error;
+	}
+
+	return 0;
+} /* dns_res_check() */
+
+
+struct dns_packet *dns_res_fetch(struct dns_resolver *R, int *_error) {
+	struct dns_packet *P = NULL;
+	int error;
+
+	if (R->stack[0].state != DNS_R_DONE) {
+		error = DNS_EUNKNOWN;
+		goto error;
+	}
+
+	if (!dns_p_movptr(&P, &R->stack[0].answer)) {
+		error = DNS_EFETCHED;
+		goto error;
+	}
+
+	dns_trace_res_fetch(R->trace, P, 0);
+
+	return P;
+error:
+	*_error = error;
+	dns_trace_res_fetch(R->trace, NULL, error);
+	return NULL;
+} /* dns_res_fetch() */
+
+
+static struct dns_packet *dns_res_fetch_and_study(struct dns_resolver *R, int *_error) {
+	struct dns_packet *P = NULL;
+	int error;
+
+	if (!(P = dns_res_fetch(R, &error)))
+		goto error;
+	if ((error = dns_p_study(P)))
+		goto error;
+
+	return P;
+error:
+	*_error = error;
+
+	dns_p_free(P);
+
+	return NULL;
+} /* dns_res_fetch_and_study() */
+
+
+struct dns_packet *dns_res_query(struct dns_resolver *res, const char *qname, enum dns_type qtype, enum dns_class qclass, int timeout, int *error_) {
+	int error;
+
+	if ((error = dns_res_submit(res, qname, qtype, qclass)))
+		goto error;
+
+	while ((error = dns_res_check(res))) {
+		if (dns_res_elapsed(res) > timeout)
+			error = DNS_ETIMEDOUT;
+
+		if (error != DNS_EAGAIN)
+			goto error;
+
+		if ((error = dns_res_poll(res, 1)))
+			goto error;
+	}
+
+	return dns_res_fetch(res, error_);
+error:
+	*error_ = error;
+
+	return 0;
+} /* dns_res_query() */
+
+
+const struct dns_stat *dns_res_stat(struct dns_resolver *res) {
+	return dns_so_stat(&res->so);
+} /* dns_res_stat() */
+
+
+void dns_res_sethints(struct dns_resolver *res, struct dns_hints *hints) {
+	dns_hints_acquire(hints); /* acquire first in case same hints object */
+	dns_hints_close(res->hints);
+	res->hints = hints;
+} /* dns_res_sethints() */
+
+
+struct dns_trace *dns_res_trace(struct dns_resolver *res) {
+	return res->trace;
+} /* dns_res_trace() */
+
+
+void dns_res_settrace(struct dns_resolver *res, struct dns_trace *trace) {
+	struct dns_trace *otrace = res->trace;
+	res->trace = dns_trace_acquire_p(trace);
+	dns_trace_close(otrace);
+	dns_so_settrace(&res->so, trace);
+} /* dns_res_settrace() */
+
+
+/*
+ * A D D R I N F O  R O U T I N E S
+ *
+ * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
+
+struct dns_addrinfo {
+	struct addrinfo hints;
+	struct dns_resolver *res;
+	struct dns_trace *trace;
+
+	char qname[DNS_D_MAXNAME + 1];
+	enum dns_type qtype;
+	unsigned short qport, port;
+
+	struct {
+		unsigned long todo;
+		int state;
+		int atype;
+		enum dns_type qtype;
+	} af;
+
+	struct dns_packet *answer;
+	struct dns_packet *glue;
+
+	struct dns_rr_i i, g;
+	struct dns_rr rr;
+
+	char cname[DNS_D_MAXNAME + 1];
+	char i_cname[DNS_D_MAXNAME + 1], g_cname[DNS_D_MAXNAME + 1];
+
+	int g_depth;
+
+	int state;
+	int found;
+
+	struct dns_stat st;
+}; /* struct dns_addrinfo */
+
+
+#define DNS_AI_AFMAX 32
+#define DNS_AI_AF2INDEX(af) (1UL << ((af) - 1))
+
+static inline unsigned long dns_ai_af2index(int af) {
+	dns_static_assert(dns_same_type(unsigned long, DNS_AI_AF2INDEX(1), 1), "internal type mismatch");
+	dns_static_assert(dns_same_type(unsigned long, ((struct dns_addrinfo *)0)->af.todo, 1), "internal type mismatch");
+
+	return (af > 0 && af <= DNS_AI_AFMAX)? DNS_AI_AF2INDEX(af) : 0;
+}
+
+static int dns_ai_setaf(struct dns_addrinfo *ai, int af, int qtype) {
+	ai->af.atype = af;
+	ai->af.qtype = qtype;
+
+	ai->af.todo &= ~dns_ai_af2index(af);
+
+	return af;
+} /* dns_ai_setaf() */
+
+#define DNS_SM_RESTORE \
+	do { pc = 0xff & (ai->af.state >> 0); i = 0xff & (ai->af.state >> 8); } while (0)
+#define DNS_SM_SAVE \
+	do { ai->af.state = ((0xff & pc) << 0) | ((0xff & i) << 8); } while (0)
+
+static int dns_ai_nextaf(struct dns_addrinfo *ai) {
+	int i, pc;
+
+	dns_static_assert(AF_UNSPEC == 0, "AF_UNSPEC constant not 0");
+	dns_static_assert(AF_INET <= DNS_AI_AFMAX, "AF_INET constant too large");
+	dns_static_assert(AF_INET6 <= DNS_AI_AFMAX, "AF_INET6 constant too large");
+
+	DNS_SM_ENTER;
+
+	if (ai->res) {
+		/*
+		 * NB: On OpenBSD, at least, the types of entries resolved
+		 * is the intersection of the /etc/resolv.conf families and
+		 * the families permitted by the .ai_type hint. So if
+		 * /etc/resolv.conf has "family inet4" and .ai_type
+		 * is AF_INET6, then the address ::1 will return 0 entries
+		 * even if AI_NUMERICHOST is specified in .ai_flags.
+		 */
+		while (i < (int)lengthof(ai->res->resconf->family)) {
+			int af = ai->res->resconf->family[i++];
+
+			if (af == AF_UNSPEC) {
+				DNS_SM_EXIT;
+			} else if (af < 0 || af > DNS_AI_AFMAX) {
+				continue;
+			} else if (!(DNS_AI_AF2INDEX(af) & ai->af.todo)) {
+				continue;
+			} else if (af == AF_INET) {
+				DNS_SM_YIELD(dns_ai_setaf(ai, AF_INET, DNS_T_A));
+			} else if (af == AF_INET6) {
+				DNS_SM_YIELD(dns_ai_setaf(ai, AF_INET6, DNS_T_AAAA));
+			}
+		}
+	} else {
+		/*
+		 * NB: If we get here than AI_NUMERICFLAGS should be set and
+		 * order shouldn't matter.
+		 */
+		if (DNS_AI_AF2INDEX(AF_INET) & ai->af.todo)
+			DNS_SM_YIELD(dns_ai_setaf(ai, AF_INET, DNS_T_A));
+		if (DNS_AI_AF2INDEX(AF_INET6) & ai->af.todo)
+			DNS_SM_YIELD(dns_ai_setaf(ai, AF_INET6, DNS_T_AAAA));
+	}
+
+	DNS_SM_LEAVE;
+
+	return dns_ai_setaf(ai, AF_UNSPEC, 0);
+} /* dns_ai_nextaf() */
+
+#undef DNS_SM_RESTORE
+#undef DNS_SM_SAVE
+
+static enum dns_type dns_ai_qtype(struct dns_addrinfo *ai) {
+	return (ai->qtype)? ai->qtype : ai->af.qtype;
+} /* dns_ai_qtype() */
+
+/* JW: This is not defined on mingw.  */
+#ifndef AI_NUMERICSERV
+#define AI_NUMERICSERV	0
+#endif
+
+static dns_error_t dns_ai_parseport(unsigned short *port, const char *serv, const struct addrinfo *hints) {
+	const char *cp = serv;
+	unsigned long n = 0;
+
+	while (*cp >= '0' && *cp <= '9' && n < 65536) {
+		n *= 10;
+		n += *cp++ - '0';
+	}
+
+	if (*cp == '\0') {
+		if (cp == serv || n >= 65536)
+			return DNS_ESERVICE;
+
+		*port = n;
+
+		return 0;
+	}
+
+	if (hints->ai_flags & AI_NUMERICSERV)
+		return DNS_ESERVICE;
+
+	/* TODO: try getaddrinfo(NULL, serv, { .ai_flags = AI_NUMERICSERV }) */
+
+	return DNS_ESERVICE;
+} /* dns_ai_parseport() */
+
+
+struct dns_addrinfo *dns_ai_open(const char *host, const char *serv, enum dns_type qtype, const struct addrinfo *hints, struct dns_resolver *res, int *_error) {
+	static const struct dns_addrinfo ai_initializer;
+	struct dns_addrinfo *ai;
+	int error;
+
+	if (res) {
+		dns_res_acquire(res);
+	} else if (!(hints->ai_flags & AI_NUMERICHOST)) {
+		/*
+		 * NOTE: it's assumed that *_error is set from a previous
+		 * API function call, such as dns_res_stub(). Should change
+		 * this semantic, but it's applied elsewhere, too.
+		 */
+		if (!*_error)
+			*_error = EINVAL;
+		return NULL;
+	}
+
+	if (!(ai = malloc(sizeof *ai)))
+		goto syerr;
+
+	*ai = ai_initializer;
+	ai->hints = *hints;
+
+	ai->res = res;
+	res = NULL;
+
+	if (sizeof ai->qname <= dns_strlcpy(ai->qname, host, sizeof ai->qname))
+		{ error = ENAMETOOLONG; goto error; }
+
+	ai->qtype = qtype;
+	ai->qport = 0;
+
+	if (serv && (error = dns_ai_parseport(&ai->qport, serv, hints)))
+		goto error;
+	ai->port = ai->qport;
+
+	/*
+	 * FIXME: If an explicit A or AAAA record type conflicts with
+	 * .ai_family or with resconf.family (i.e. AAAA specified but
+	 * AF_INET6 not in interection of .ai_family and resconf.family),
+	 * then what?
+	 */
+	switch (ai->qtype) {
+	case DNS_T_A:
+		ai->af.todo = DNS_AI_AF2INDEX(AF_INET);
+		break;
+	case DNS_T_AAAA:
+		ai->af.todo = DNS_AI_AF2INDEX(AF_INET6);
+		break;
+	default: /* 0, MX, SRV, etc */
+		switch (ai->hints.ai_family) {
+		case AF_UNSPEC:
+			ai->af.todo = DNS_AI_AF2INDEX(AF_INET) | DNS_AI_AF2INDEX(AF_INET6);
+			break;
+		case AF_INET:
+			ai->af.todo = DNS_AI_AF2INDEX(AF_INET);
+			break;
+		case AF_INET6:
+			ai->af.todo = DNS_AI_AF2INDEX(AF_INET6);
+			break;
+		default:
+			break;
+		}
+	}
+
+	return ai;
+syerr:
+	error = dns_syerr();
+error:
+	*_error = error;
+
+	dns_ai_close(ai);
+	dns_res_close(res);
+
+	return NULL;
+} /* dns_ai_open() */
+
+
+void dns_ai_close(struct dns_addrinfo *ai) {
+	if (!ai)
+		return;
+
+	dns_res_close(ai->res);
+	dns_trace_close(ai->trace);
+
+	if (ai->answer != ai->glue)
+		dns_p_free(ai->glue);
+
+	dns_p_free(ai->answer);
+	free(ai);
+} /* dns_ai_close() */
+
+
+static int dns_ai_setent(struct addrinfo **ent, union dns_any *any, enum dns_type type, struct dns_addrinfo *ai) {
+	struct sockaddr *saddr;
+	struct sockaddr_in sin;
+	struct sockaddr_in6 sin6;
+	const char *cname;
+	size_t clen;
+
+	switch (type) {
+	case DNS_T_A:
+		saddr	= memset(&sin, '\0', sizeof sin);
+
+		sin.sin_family	= AF_INET;
+		sin.sin_port	= htons(ai->port);
+
+		memcpy(&sin.sin_addr, any, sizeof sin.sin_addr);
+
+		break;
+	case DNS_T_AAAA:
+		saddr	= memset(&sin6, '\0', sizeof sin6);
+
+		sin6.sin6_family	= AF_INET6;
+		sin6.sin6_port		= htons(ai->port);
+
+		memcpy(&sin6.sin6_addr, any, sizeof sin6.sin6_addr);
+
+		break;
+	default:
+		return EINVAL;
+	} /* switch() */
+
+	if (ai->hints.ai_flags & AI_CANONNAME) {
+		cname	= (*ai->cname)? ai->cname : ai->qname;
+		clen	= strlen(cname);
+	} else {
+		cname	= NULL;
+		clen	= 0;
+	}
+
+	if (!(*ent = malloc(sizeof **ent + dns_sa_len(saddr) + ((ai->hints.ai_flags & AI_CANONNAME)? clen + 1 : 0))))
+		return dns_syerr();
+
+	memset(*ent, '\0', sizeof **ent);
+
+	(*ent)->ai_family	= saddr->sa_family;
+	(*ent)->ai_socktype	= ai->hints.ai_socktype;
+	(*ent)->ai_protocol	= ai->hints.ai_protocol;
+
+	(*ent)->ai_addr		= memcpy((unsigned char *)*ent + sizeof **ent, saddr, dns_sa_len(saddr));
+	(*ent)->ai_addrlen	= dns_sa_len(saddr);
+
+	if (ai->hints.ai_flags & AI_CANONNAME)
+		(*ent)->ai_canonname	= memcpy((unsigned char *)*ent + sizeof **ent + dns_sa_len(saddr), cname, clen + 1);
+
+	ai->found++;
+
+	return 0;
+} /* dns_ai_setent() */
+
+
+enum dns_ai_state {
+	DNS_AI_S_INIT,
+	DNS_AI_S_NEXTAF,
+	DNS_AI_S_NUMERIC,
+	DNS_AI_S_SUBMIT,
+	DNS_AI_S_CHECK,
+	DNS_AI_S_FETCH,
+	DNS_AI_S_FOREACH_I,
+	DNS_AI_S_INIT_G,
+	DNS_AI_S_ITERATE_G,
+	DNS_AI_S_FOREACH_G,
+	DNS_AI_S_SUBMIT_G,
+	DNS_AI_S_CHECK_G,
+	DNS_AI_S_FETCH_G,
+	DNS_AI_S_DONE,
+}; /* enum dns_ai_state */
+
+#define dns_ai_goto(which)	do { ai->state = (which); goto exec; } while (0)
+
+int dns_ai_nextent(struct addrinfo **ent, struct dns_addrinfo *ai) {
+	struct dns_packet *ans, *glue;
+	struct dns_rr rr;
+	char qname[DNS_D_MAXNAME + 1];
+	union dns_any any;
+	size_t qlen, clen;
+	int error;
+
+	*ent = 0;
+
+exec:
+
+	switch (ai->state) {
+	case DNS_AI_S_INIT:
+		ai->state++;
+	case DNS_AI_S_NEXTAF:
+		if (!dns_ai_nextaf(ai))
+			dns_ai_goto(DNS_AI_S_DONE);
+
+		ai->state++;
+	case DNS_AI_S_NUMERIC:
+		if (1 == dns_inet_pton(AF_INET, ai->qname, &any.a)) {
+			if (ai->af.atype == AF_INET) {
+				ai->state = DNS_AI_S_NEXTAF;
+				return dns_ai_setent(ent, &any, DNS_T_A, ai);
+			} else {
+				dns_ai_goto(DNS_AI_S_NEXTAF);
+			}
+		}
+
+		if (1 == dns_inet_pton(AF_INET6, ai->qname, &any.aaaa)) {
+			if (ai->af.atype == AF_INET6) {
+				ai->state = DNS_AI_S_NEXTAF;
+				return dns_ai_setent(ent, &any, DNS_T_AAAA, ai);
+			} else {
+				dns_ai_goto(DNS_AI_S_NEXTAF);
+			}
+		}
+
+		if (ai->hints.ai_flags & AI_NUMERICHOST)
+			dns_ai_goto(DNS_AI_S_NEXTAF);
+
+		ai->state++;
+	case DNS_AI_S_SUBMIT:
+		assert(ai->res);
+
+		if ((error = dns_res_submit(ai->res, ai->qname, dns_ai_qtype(ai), DNS_C_IN)))
+			return error;
+
+		ai->state++;
+	case DNS_AI_S_CHECK:
+		if ((error = dns_res_check(ai->res)))
+			return error;
+
+		ai->state++;
+	case DNS_AI_S_FETCH:
+		if (!(ans = dns_res_fetch_and_study(ai->res, &error)))
+			return error;
+		if (ai->glue != ai->answer)
+			dns_p_free(ai->glue);
+		ai->glue = dns_p_movptr(&ai->answer, &ans);
+
+		/* Search generator may have changed the qname. */
+		if (!(qlen = dns_d_expand(qname, sizeof qname, 12, ai->answer, &error)))
+			return error;
+		else if (qlen >= sizeof qname)
+			return DNS_EILLEGAL;
+		if (!dns_d_cname(ai->cname, sizeof ai->cname, qname, qlen, ai->answer, &error))
+			return error;
+
+		dns_strlcpy(ai->i_cname, ai->cname, sizeof ai->i_cname);
+		dns_rr_i_init(&ai->i, ai->answer);
+		ai->i.section = DNS_S_AN;
+		ai->i.name    = ai->i_cname;
+		ai->i.type    = dns_ai_qtype(ai);
+		ai->i.sort    = &dns_rr_i_order;
+
+		ai->state++;
+	case DNS_AI_S_FOREACH_I:
+		if (!dns_rr_grep(&rr, 1, &ai->i, ai->answer, &error))
+			dns_ai_goto(DNS_AI_S_NEXTAF);
+
+		if ((error = dns_any_parse(&any, &rr, ai->answer)))
+			return error;
+
+		ai->port = ai->qport;
+
+		switch (rr.type) {
+		case DNS_T_A:
+		case DNS_T_AAAA:
+			return dns_ai_setent(ent, &any, rr.type, ai);
+		default:
+			if (!(clen = dns_any_cname(ai->cname, sizeof ai->cname, &any, rr.type)))
+				dns_ai_goto(DNS_AI_S_FOREACH_I);
+
+			/*
+			 * Find the "real" canonical name. Some authorities
+			 * publish aliases where an RFC defines a canonical
+			 * name. We trust that the resolver followed any
+			 * CNAME chains on it's own, regardless of whether
+			 * the "smart" option is enabled.
+			 */
+			if (!dns_d_cname(ai->cname, sizeof ai->cname, ai->cname, clen, ai->answer, &error))
+				return error;
+
+			if (rr.type == DNS_T_SRV)
+				ai->port = any.srv.port;
+
+			break;
+		} /* switch() */
+
+		ai->state++;
+	case DNS_AI_S_INIT_G:
+		ai->g_depth = 0;
+
+		ai->state++;
+	case DNS_AI_S_ITERATE_G:
+		dns_strlcpy(ai->g_cname, ai->cname, sizeof ai->g_cname);
+		dns_rr_i_init(&ai->g, ai->glue);
+		ai->g.section = DNS_S_ALL & ~DNS_S_QD;
+		ai->g.name    = ai->g_cname;
+		ai->g.type    = ai->af.qtype;
+
+		ai->state++;
+	case DNS_AI_S_FOREACH_G:
+		if (!dns_rr_grep(&rr, 1, &ai->g, ai->glue, &error)) {
+			if (dns_rr_i_count(&ai->g) > 0)
+				dns_ai_goto(DNS_AI_S_FOREACH_I);
+			else
+				dns_ai_goto(DNS_AI_S_SUBMIT_G);
+		}
+
+		if ((error = dns_any_parse(&any, &rr, ai->glue)))
+			return error;
+
+		return dns_ai_setent(ent, &any, rr.type, ai);
+	case DNS_AI_S_SUBMIT_G:
+		/* skip if already queried */
+		if (dns_rr_grep(&rr, 1, dns_rr_i_new(ai->glue, .section = DNS_S_QD, .name = ai->g.name, .type = ai->g.type), ai->glue, &error))
+			dns_ai_goto(DNS_AI_S_FOREACH_I);
+		/* skip if we recursed (CNAME chains should have been handled in the resolver) */
+		if (++ai->g_depth > 1)
+			dns_ai_goto(DNS_AI_S_FOREACH_I);
+
+		if ((error = dns_res_submit(ai->res, ai->g.name, ai->g.type, DNS_C_IN)))
+			return error;
+
+		ai->state++;
+	case DNS_AI_S_CHECK_G:
+		if ((error = dns_res_check(ai->res)))
+			return error;
+
+		ai->state++;
+	case DNS_AI_S_FETCH_G:
+		if (!(ans = dns_res_fetch_and_study(ai->res, &error)))
+			return error;
+
+		glue = dns_p_merge(ai->glue, DNS_S_ALL, ans, DNS_S_ALL, &error);
+		dns_p_setptr(&ans, NULL);
+		if (!glue)
+			return error;
+
+		if (ai->glue != ai->answer)
+			dns_p_free(ai->glue);
+		ai->glue = glue;
+
+		if (!dns_d_cname(ai->cname, sizeof ai->cname, ai->g.name, strlen(ai->g.name), ai->glue, &error))
+			dns_ai_goto(DNS_AI_S_FOREACH_I);
+
+		dns_ai_goto(DNS_AI_S_ITERATE_G);
+	case DNS_AI_S_DONE:
+		if (ai->found) {
+			return ENOENT; /* TODO: Just return 0 */
+		} else if (ai->answer) {
+			switch (dns_p_rcode(ai->answer)) {
+			case DNS_RC_NOERROR:
+				/* FALL THROUGH */
+			case DNS_RC_NXDOMAIN:
+				return DNS_ENONAME;
+			default:
+				return DNS_EFAIL;
+			}
+		} else {
+			return DNS_EFAIL;
+		}
+	default:
+		return EINVAL;
+	} /* switch() */
+} /* dns_ai_nextent() */
+
+
+time_t dns_ai_elapsed(struct dns_addrinfo *ai) {
+	return (ai->res)? dns_res_elapsed(ai->res) : 0;
+} /* dns_ai_elapsed() */
+
+
+void dns_ai_clear(struct dns_addrinfo *ai) {
+	if (ai->res)
+		dns_res_clear(ai->res);
+} /* dns_ai_clear() */
+
+
+int dns_ai_events(struct dns_addrinfo *ai) {
+	return (ai->res)? dns_res_events(ai->res) : 0;
+} /* dns_ai_events() */
+
+
+int dns_ai_pollfd(struct dns_addrinfo *ai) {
+	return (ai->res)? dns_res_pollfd(ai->res) : -1;
+} /* dns_ai_pollfd() */
+
+
+time_t dns_ai_timeout(struct dns_addrinfo *ai) {
+	return (ai->res)? dns_res_timeout(ai->res) : 0;
+} /* dns_ai_timeout() */
+
+
+int dns_ai_poll(struct dns_addrinfo *ai, int timeout) {
+	return (ai->res)? dns_res_poll(ai->res, timeout) : 0;
+} /* dns_ai_poll() */
+
+
+size_t dns_ai_print(void *_dst, size_t lim, struct addrinfo *ent, struct dns_addrinfo *ai) {
+	struct dns_buf dst = DNS_B_INTO(_dst, lim);
+	char addr[DNS_PP_MAX(INET_ADDRSTRLEN, INET6_ADDRSTRLEN) + 1];
+
+	dns_b_puts(&dst, "[ ");
+	dns_b_puts(&dst, ai->qname);
+	dns_b_puts(&dst, " IN ");
+	if (ai->qtype) {
+		dns_b_puts(&dst, dns_strtype(ai->qtype));
+	} else if (ent->ai_family == AF_INET) {
+		dns_b_puts(&dst, dns_strtype(DNS_T_A));
+	} else if (ent->ai_family == AF_INET6) {
+		dns_b_puts(&dst, dns_strtype(DNS_T_AAAA));
+	} else {
+		dns_b_puts(&dst, "0");
+	}
+	dns_b_puts(&dst, " ]\n");
+
+	dns_b_puts(&dst, ".ai_family    = ");
+	switch (ent->ai_family) {
+	case AF_INET:
+		dns_b_puts(&dst, "AF_INET");
+		break;
+	case AF_INET6:
+		dns_b_puts(&dst, "AF_INET6");
+		break;
+	default:
+		dns_b_fmtju(&dst, ent->ai_family, 0);
+		break;
+	}
+	dns_b_putc(&dst, '\n');
+
+	dns_b_puts(&dst, ".ai_socktype  = ");
+	switch (ent->ai_socktype) {
+	case SOCK_STREAM:
+		dns_b_puts(&dst, "SOCK_STREAM");
+		break;
+	case SOCK_DGRAM:
+		dns_b_puts(&dst, "SOCK_DGRAM");
+		break;
+	default:
+		dns_b_fmtju(&dst, ent->ai_socktype, 0);
+		break;
+	}
+	dns_b_putc(&dst, '\n');
+
+	dns_inet_ntop(dns_sa_family(ent->ai_addr), dns_sa_addr(dns_sa_family(ent->ai_addr), ent->ai_addr, NULL), addr, sizeof addr);
+	dns_b_puts(&dst, ".ai_addr      = [");
+	dns_b_puts(&dst, addr);
+	dns_b_puts(&dst, "]:");
+	dns_b_fmtju(&dst, ntohs(*dns_sa_port(dns_sa_family(ent->ai_addr), ent->ai_addr)), 0);
+	dns_b_putc(&dst, '\n');
+
+	dns_b_puts(&dst, ".ai_canonname = ");
+	dns_b_puts(&dst, (ent->ai_canonname)? ent->ai_canonname : "[NULL]");
+	dns_b_putc(&dst, '\n');
+
+	return dns_b_strllen(&dst);
+} /* dns_ai_print() */
+
+
+const struct dns_stat *dns_ai_stat(struct dns_addrinfo *ai) {
+	return (ai->res)? dns_res_stat(ai->res) : &ai->st;
+} /* dns_ai_stat() */
+
+
+struct dns_trace *dns_ai_trace(struct dns_addrinfo *ai) {
+	return ai->trace;
+} /* dns_ai_trace() */
+
+
+void dns_ai_settrace(struct dns_addrinfo *ai, struct dns_trace *trace) {
+	struct dns_trace *otrace = ai->trace;
+	ai->trace = dns_trace_acquire_p(trace);
+	dns_trace_close(otrace);
+	if (ai->res)
+		dns_res_settrace(ai->res, trace);
+} /* dns_ai_settrace() */
+
+
+/*
+ * M I S C E L L A N E O U S  R O U T I N E S
+ *
+ * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
+
+static const struct {
+	char name[16];
+	enum dns_section type;
+} dns_sections[] = {
+	{ "QUESTION",   DNS_S_QUESTION },
+	{ "QD",         DNS_S_QUESTION },
+	{ "ANSWER",     DNS_S_ANSWER },
+	{ "AN",         DNS_S_ANSWER },
+	{ "AUTHORITY",  DNS_S_AUTHORITY },
+	{ "NS",         DNS_S_AUTHORITY },
+	{ "ADDITIONAL", DNS_S_ADDITIONAL },
+	{ "AR",         DNS_S_ADDITIONAL },
+};
+
+const char *(dns_strsection)(enum dns_section section, void *_dst, size_t lim) {
+	struct dns_buf dst = DNS_B_INTO(_dst, lim);
+	unsigned i;
+
+	for (i = 0; i < lengthof(dns_sections); i++) {
+		if (dns_sections[i].type & section) {
+			dns_b_puts(&dst, dns_sections[i].name);
+			section &= ~dns_sections[i].type;
+			if (section)
+				dns_b_putc(&dst, '|');
+		}
+	}
+
+	if (section || dst.p == dst.base)
+		dns_b_fmtju(&dst, (0xffff & section), 0);
+
+	return dns_b_tostring(&dst);
+} /* dns_strsection() */
+
+
+enum dns_section dns_isection(const char *src) {
+	enum dns_section section = 0;
+	char sbuf[128];
+	char *name, *next;
+	unsigned i;
+
+	dns_strlcpy(sbuf, src, sizeof sbuf);
+	next = sbuf;
+
+	while ((name = dns_strsep(&next, "|+, \t"))) {
+		for (i = 0; i < lengthof(dns_sections); i++) {
+			if (!strcasecmp(dns_sections[i].name, name)) {
+				section |= dns_sections[i].type;
+				break;
+			}
+		}
+	}
+
+	return section;
+} /* dns_isection() */
+
+
+static const struct {
+	char name[8];
+	enum dns_class type;
+} dns_classes[] = {
+	{ "IN", DNS_C_IN },
+};
+
+const char *(dns_strclass)(enum dns_class type, void *_dst, size_t lim) {
+	struct dns_buf dst = DNS_B_INTO(_dst, lim);
+	unsigned i;
+
+	for (i = 0; i < lengthof(dns_classes); i++) {
+		if (dns_classes[i].type == type) {
+			dns_b_puts(&dst, dns_classes[i].name);
+			break;
+		}
+	}
+
+	if (dst.p == dst.base)
+		dns_b_fmtju(&dst, (0xffff & type), 0);
+
+	return dns_b_tostring(&dst);
+} /* dns_strclass() */
+
+
+enum dns_class dns_iclass(const char *name) {
+	unsigned i, class;
+
+	for (i = 0; i < lengthof(dns_classes); i++) {
+		if (!strcasecmp(dns_classes[i].name, name))
+			return dns_classes[i].type;
+	}
+
+	class = 0;
+	while (dns_isdigit(*name)) {
+		class *= 10;
+		class += *name++ - '0';
+	}
+
+	return DNS_PP_MIN(class, 0xffff);
+} /* dns_iclass() */
+
+
+const char *(dns_strtype)(enum dns_type type, void *_dst, size_t lim) {
+	struct dns_buf dst = DNS_B_INTO(_dst, lim);
+	unsigned i;
+
+	for (i = 0; i < lengthof(dns_rrtypes); i++) {
+		if (dns_rrtypes[i].type == type) {
+			dns_b_puts(&dst, dns_rrtypes[i].name);
+			break;
+		}
+	}
+
+	if (dst.p == dst.base)
+		dns_b_fmtju(&dst, (0xffff & type), 0);
+
+	return dns_b_tostring(&dst);
+} /* dns_strtype() */
+
+
+enum dns_type dns_itype(const char *name) {
+	unsigned i, type;
+
+	for (i = 0; i < lengthof(dns_rrtypes); i++) {
+		if (!strcasecmp(dns_rrtypes[i].name, name))
+			return dns_rrtypes[i].type;
+	}
+
+	type = 0;
+	while (dns_isdigit(*name)) {
+		type *= 10;
+		type += *name++ - '0';
+	}
+
+	return DNS_PP_MIN(type, 0xffff);
+} /* dns_itype() */
+
+
+static char dns_opcodes[16][16] = {
+	[DNS_OP_QUERY]  = "QUERY",
+	[DNS_OP_IQUERY] = "IQUERY",
+	[DNS_OP_STATUS] = "STATUS",
+	[DNS_OP_NOTIFY] = "NOTIFY",
+	[DNS_OP_UPDATE] = "UPDATE",
+};
+
+static const char *dns__strcode(int code, volatile char *dst, size_t lim) {
+	char _tmp[48] = "";
+	struct dns_buf tmp;
+	size_t p;
+
+	assert(lim > 0);
+	dns_b_fmtju(dns_b_into(&tmp, _tmp, DNS_PP_MIN(sizeof _tmp, lim - 1)), code, 0);
+
+	/* copy downwards so first byte is copied last (see below) */
+	p = (size_t)(tmp.p - tmp.base);
+	dst[p] = '\0';
+	while (p--)
+		dst[p] = _tmp[p];
+
+	return (const char *)dst;
+}
+
+const char *dns_stropcode(enum dns_opcode opcode) {
+	opcode = (unsigned)opcode % lengthof(dns_opcodes);
+
+	if ('\0' == dns_opcodes[opcode][0])
+		return dns__strcode(opcode, dns_opcodes[opcode], sizeof dns_opcodes[opcode]);
+
+	return dns_opcodes[opcode];
+} /* dns_stropcode() */
+
+
+enum dns_opcode dns_iopcode(const char *name) {
+	unsigned opcode;
+
+	for (opcode = 0; opcode < lengthof(dns_opcodes); opcode++) {
+		if (!strcasecmp(name, dns_opcodes[opcode]))
+			return opcode;
+	}
+
+	opcode = 0;
+	while (dns_isdigit(*name)) {
+		opcode *= 10;
+		opcode += *name++ - '0';
+	}
+
+	return DNS_PP_MIN(opcode, 0x0f);
+} /* dns_iopcode() */
+
+
+static char dns_rcodes[32][16] = {
+	[DNS_RC_NOERROR]  = "NOERROR",
+	[DNS_RC_FORMERR]  = "FORMERR",
+	[DNS_RC_SERVFAIL] = "SERVFAIL",
+	[DNS_RC_NXDOMAIN] = "NXDOMAIN",
+	[DNS_RC_NOTIMP]   = "NOTIMP",
+	[DNS_RC_REFUSED]  = "REFUSED",
+	[DNS_RC_YXDOMAIN] = "YXDOMAIN",
+	[DNS_RC_YXRRSET]  = "YXRRSET",
+	[DNS_RC_NXRRSET]  = "NXRRSET",
+	[DNS_RC_NOTAUTH]  = "NOTAUTH",
+	[DNS_RC_NOTZONE]  = "NOTZONE",
+	/* EDNS(0) extended RCODEs ... */
+	[DNS_RC_BADVERS]  = "BADVERS",
+};
+
+const char *dns_strrcode(enum dns_rcode rcode) {
+	rcode = (unsigned)rcode % lengthof(dns_rcodes);
+
+	if ('\0' == dns_rcodes[rcode][0])
+		return dns__strcode(rcode, dns_rcodes[rcode], sizeof dns_rcodes[rcode]);
+
+	return dns_rcodes[rcode];
+} /* dns_strrcode() */
+
+
+enum dns_rcode dns_ircode(const char *name) {
+	unsigned rcode;
+
+	for (rcode = 0; rcode < lengthof(dns_rcodes); rcode++) {
+		if (!strcasecmp(name, dns_rcodes[rcode]))
+			return rcode;
+	}
+
+	rcode = 0;
+	while (dns_isdigit(*name)) {
+		rcode *= 10;
+		rcode += *name++ - '0';
+	}
+
+	return DNS_PP_MIN(rcode, 0xfff);
+} /* dns_ircode() */
+
+
+
+/*
+ * C O M M A N D - L I N E / R E G R E S S I O N  R O U T I N E S
+ *
+ * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
+#if DNS_MAIN
+
+#include <stdarg.h>
+#include <stdlib.h>
+#include <stdio.h>
+
+#include <ctype.h>
+
+#if _WIN32
+#include <getopt.h>
+#endif
+
+#if !_WIN32
+#include <err.h>
+#endif
+
+
+struct {
+	struct {
+		const char *path[8];
+		unsigned count;
+	} resconf, nssconf, hosts, cache;
+
+	const char *qname;
+	enum dns_type qtype;
+
+	int (*sort)();
+
+	const char *trace;
+
+	int verbose;
+
+	struct {
+		struct dns_resolv_conf *resconf;
+		struct dns_hosts *hosts;
+		struct dns_trace *trace;
+	} memo;
+
+	struct sockaddr_storage socks_host;
+} MAIN = {
+	.sort	= &dns_rr_i_packet,
+};
+
+
+static void hexdump(const unsigned char *src, size_t len, FILE *fp) {
+	struct dns_hxd_lines_i lines = { 0 };
+	char line[128];
+
+	while (dns_hxd_lines(line, sizeof line, src, len, &lines)) {
+		fputs(line, fp);
+	}
+} /* hexdump() */
+
+
+DNS_NORETURN static void panic(const char *fmt, ...) {
+	va_list ap;
+
+	va_start(ap, fmt);
+
+#if _WIN32
+	vfprintf(stderr, fmt, ap);
+
+	exit(EXIT_FAILURE);
+#else
+	verrx(EXIT_FAILURE, fmt, ap);
+#endif
+} /* panic() */
+
+#define panic_(fn, ln, fmt, ...)	\
+	panic(fmt "%0s", (fn), (ln), __VA_ARGS__)
+#define panic(...)			\
+	panic_(__func__, __LINE__, "(%s:%d) " __VA_ARGS__, "")
+
+
+static void *grow(unsigned char *p, size_t size) {
+	void *tmp;
+
+	if (!(tmp = realloc(p, size)))
+		panic("realloc(%"PRIuZ"): %s", size, dns_strerror(errno));
+
+	return tmp;
+} /* grow() */
+
+
+static size_t add(size_t a, size_t b) {
+	if (~a < b)
+		panic("%"PRIuZ" + %"PRIuZ": integer overflow", a, b);
+
+	return a + b;
+} /* add() */
+
+
+static size_t append(unsigned char **dst, size_t osize, const void *src, size_t len) {
+	size_t size = add(osize, len);
+
+	*dst = grow(*dst, size);
+	memcpy(*dst + osize, src, len);
+
+	return size;
+} /* append() */
+
+
+static size_t slurp(unsigned char **dst, size_t osize, FILE *fp, const char *path) {
+	size_t size = osize;
+	unsigned char buf[1024];
+	size_t count;
+
+	while ((count = fread(buf, 1, sizeof buf, fp)))
+		size = append(dst, size, buf, count);
+
+	if (ferror(fp))
+		panic("%s: %s", path, dns_strerror(errno));
+
+	return size;
+} /* slurp() */
+
+
+static struct dns_resolv_conf *resconf(void) {
+	struct dns_resolv_conf **resconf = &MAIN.memo.resconf;
+	const char *path;
+	unsigned i;
+	int error;
+
+	if (*resconf)
+		return *resconf;
+
+	if (!(*resconf = dns_resconf_open(&error)))
+		panic("dns_resconf_open: %s", dns_strerror(error));
+
+	if (!MAIN.resconf.count)
+		MAIN.resconf.path[MAIN.resconf.count++]	= "/etc/resolv.conf";
+
+	for (i = 0; i < MAIN.resconf.count; i++) {
+		path	= MAIN.resconf.path[i];
+
+		if (0 == strcmp(path, "-"))
+			error	= dns_resconf_loadfile(*resconf, stdin);
+		else
+			error	= dns_resconf_loadpath(*resconf, path);
+
+		if (error)
+			panic("%s: %s", path, dns_strerror(error));
+	}
+
+	for (i = 0; i < MAIN.nssconf.count; i++) {
+		path	= MAIN.nssconf.path[i];
+
+		if (0 == strcmp(path, "-"))
+			error	= dns_nssconf_loadfile(*resconf, stdin);
+		else
+			error	= dns_nssconf_loadpath(*resconf, path);
+
+		if (error)
+			panic("%s: %s", path, dns_strerror(error));
+	}
+
+	if (!MAIN.nssconf.count) {
+		path = "/etc/nsswitch.conf";
+
+		if (!(error = dns_nssconf_loadpath(*resconf, path)))
+			MAIN.nssconf.path[MAIN.nssconf.count++] = path;
+		else if (error != ENOENT)
+			panic("%s: %s", path, dns_strerror(error));
+	}
+
+	return *resconf;
+} /* resconf() */
+
+
+static struct dns_hosts *hosts(void) {
+	struct dns_hosts **hosts = &MAIN.memo.hosts;
+	const char *path;
+	unsigned i;
+	int error;
+
+	if (*hosts)
+		return *hosts;
+
+	if (!MAIN.hosts.count) {
+		MAIN.hosts.path[MAIN.hosts.count++]	= "/etc/hosts";
+
+		/* Explicitly test dns_hosts_local() */
+		if (!(*hosts = dns_hosts_local(&error)))
+			panic("%s: %s", "/etc/hosts", dns_strerror(error));
+
+		return *hosts;
+	}
+
+	if (!(*hosts = dns_hosts_open(&error)))
+		panic("dns_hosts_open: %s", dns_strerror(error));
+
+	for (i = 0; i < MAIN.hosts.count; i++) {
+		path	= MAIN.hosts.path[i];
+
+		if (0 == strcmp(path, "-"))
+			error	= dns_hosts_loadfile(*hosts, stdin);
+		else
+			error	= dns_hosts_loadpath(*hosts, path);
+
+		if (error)
+			panic("%s: %s", path, dns_strerror(error));
+	}
+
+	return *hosts;
+} /* hosts() */
+
+
+#if DNS_CACHE
+#include "cache.h"
+
+static struct dns_cache *cache(void) {
+	static struct cache *cache;
+	const char *path;
+	unsigned i;
+	int error;
+
+	if (cache)
+		return cache_resi(cache);
+	if (!MAIN.cache.count)
+		return NULL;
+
+	if (!(cache = cache_open(&error)))
+		panic("%s: %s", MAIN.cache.path[0], dns_strerror(error));
+
+	for (i = 0; i < MAIN.cache.count; i++) {
+		path = MAIN.cache.path[i];
+
+		if (!strcmp(path, "-")) {
+			if ((error = cache_loadfile(cache, stdin, NULL, 0)))
+				panic("%s: %s", path, dns_strerror(error));
+		} else if ((error = cache_loadpath(cache, path, NULL, 0)))
+			panic("%s: %s", path, dns_strerror(error));
+	}
+
+	return cache_resi(cache);
+} /* cache() */
+#else
+static struct dns_cache *cache(void) { return NULL; }
+#endif
+
+
+static struct dns_trace *trace(const char *mode) {
+	static char omode[64] = "";
+	struct dns_trace **trace = &MAIN.memo.trace;
+	FILE *fp;
+	int error;
+
+	if (*trace && 0 == strcmp(omode, mode))
+		return *trace;
+	if (!MAIN.trace)
+		return NULL;
+
+	if (!(fp = fopen(MAIN.trace, mode)))
+		panic("%s: %s", MAIN.trace, strerror(errno));
+	dns_trace_close(*trace);
+	if (!(*trace = dns_trace_open(fp, &error)))
+		panic("%s: %s", MAIN.trace, dns_strerror(error));
+	dns_strlcpy(omode, mode, sizeof omode);
+
+	return *trace;
+}
+
+
+static void print_packet(struct dns_packet *P, FILE *fp) {
+	dns_p_dump3(P, dns_rr_i_new(P, .sort = MAIN.sort), fp);
+
+	if (MAIN.verbose > 2)
+		hexdump(P->data, P->end, fp);
+} /* print_packet() */
+
+
+static int parse_packet(int argc DNS_NOTUSED, char *argv[] DNS_NOTUSED) {
+	struct dns_packet *P	= dns_p_new(512);
+	struct dns_packet *Q	= dns_p_new(512);
+	enum dns_section section;
+	struct dns_rr rr;
+	int error;
+	union dns_any any;
+	char pretty[sizeof any * 2];
+	size_t len;
+
+	P->end	= fread(P->data, 1, P->size, stdin);
+
+	fputs(";; [HEADER]\n", stdout);
+	fprintf(stdout, ";;     qr : %s(%d)\n", (dns_header(P)->qr)? "RESPONSE" : "QUERY", dns_header(P)->qr);
+	fprintf(stdout, ";; opcode : %s(%d)\n", dns_stropcode(dns_header(P)->opcode), dns_header(P)->opcode);
+	fprintf(stdout, ";;     aa : %s(%d)\n", (dns_header(P)->aa)? "AUTHORITATIVE" : "NON-AUTHORITATIVE", dns_header(P)->aa);
+	fprintf(stdout, ";;     tc : %s(%d)\n", (dns_header(P)->tc)? "TRUNCATED" : "NOT-TRUNCATED", dns_header(P)->tc);
+	fprintf(stdout, ";;     rd : %s(%d)\n", (dns_header(P)->rd)? "RECURSION-DESIRED" : "RECURSION-NOT-DESIRED", dns_header(P)->rd);
+	fprintf(stdout, ";;     ra : %s(%d)\n", (dns_header(P)->ra)? "RECURSION-ALLOWED" : "RECURSION-NOT-ALLOWED", dns_header(P)->ra);
+	fprintf(stdout, ";;  rcode : %s(%d)\n", dns_strrcode(dns_p_rcode(P)), dns_p_rcode(P));
+
+	section	= 0;
+
+	dns_rr_foreach(&rr, P, .sort = MAIN.sort) {
+		if (section != rr.section)
+			fprintf(stdout, "\n;; [%s:%d]\n", dns_strsection(rr.section), dns_p_count(P, rr.section));
+
+		if ((len = dns_rr_print(pretty, sizeof pretty, &rr, P, &error)))
+			fprintf(stdout, "%s\n", pretty);
+
+		dns_rr_copy(Q, &rr, P);
+
+		section	= rr.section;
+	}
+
+	fputs("; ; ; ; ; ; ; ;\n\n", stdout);
+
+	section	= 0;
+
+#if 0
+	dns_rr_foreach(&rr, Q, .name = "ns8.yahoo.com.") {
+#else
+	struct dns_rr rrset[32];
+	struct dns_rr_i *rri	= dns_rr_i_new(Q, .name = dns_d_new("ns8.yahoo.com", DNS_D_ANCHOR), .sort = MAIN.sort);
+	unsigned rrcount	= dns_rr_grep(rrset, lengthof(rrset), rri, Q, &error);
+
+	for (unsigned i = 0; i < rrcount; i++) {
+		rr	= rrset[i];
+#endif
+		if (section != rr.section)
+			fprintf(stdout, "\n;; [%s:%d]\n", dns_strsection(rr.section), dns_p_count(Q, rr.section));
+
+		if ((len = dns_rr_print(pretty, sizeof pretty, &rr, Q, &error)))
+			fprintf(stdout, "%s\n", pretty);
+
+		section	= rr.section;
+	}
+
+	if (MAIN.verbose > 1) {
+		fprintf(stderr, "orig:%"PRIuZ"\n", P->end);
+		hexdump(P->data, P->end, stdout);
+
+		fprintf(stderr, "copy:%"PRIuZ"\n", Q->end);
+		hexdump(Q->data, Q->end, stdout);
+	}
+
+	return 0;
+} /* parse_packet() */
+
+
+static int parse_domain(int argc, char *argv[]) {
+	char *dn;
+
+	dn	= (argc > 1)? argv[1] : "f.l.google.com";
+
+	printf("[%s]\n", dn);
+
+	dn	= dns_d_new(dn);
+
+	do {
+		puts(dn);
+	} while (dns_d_cleave(dn, strlen(dn) + 1, dn, strlen(dn)));
+
+	return 0;
+} /* parse_domain() */
+
+
+static int trim_domain(int argc, char **argv) {
+	for (argc--, argv++; argc > 0; argc--, argv++) {
+		char name[DNS_D_MAXNAME + 1];
+
+		dns_d_trim(name, sizeof name, *argv, strlen(*argv), DNS_D_ANCHOR);
+
+		puts(name);
+	}
+
+	return 0;
+} /* trim_domain() */
+
+
+static int expand_domain(int argc, char *argv[]) {
+	unsigned short rp = 0;
+	unsigned char *src = NULL;
+	unsigned char *dst;
+	struct dns_packet *pkt;
+	size_t lim = 0, len;
+	int error;
+
+	if (argc > 1)
+		rp = atoi(argv[1]);
+
+	len = slurp(&src, 0, stdin, "-");
+
+	if (!(pkt = dns_p_make(len, &error)))
+		panic("malloc(%"PRIuZ"): %s", len, dns_strerror(error));
+
+	memcpy(pkt->data, src, len);
+	pkt->end = len;
+
+	lim = 1;
+	dst = grow(NULL, lim);
+
+	while (lim <= (len = dns_d_expand(dst, lim, rp, pkt, &error))) {
+		lim = add(len, 1);
+		dst = grow(dst, lim);
+	}
+
+	if (!len)
+		panic("expand: %s", dns_strerror(error));
+
+	fwrite(dst, 1, len, stdout);
+	fflush(stdout);
+
+	free(src);
+	free(dst);
+	free(pkt);
+
+	return 0;
+} /* expand_domain() */
+
+
+static int show_resconf(int argc DNS_NOTUSED, char *argv[] DNS_NOTUSED) {
+	unsigned i;
+
+	resconf(); /* load it */
+
+	fputs("; SOURCES\n", stdout);
+
+	for (i = 0; i < MAIN.resconf.count; i++)
+		fprintf(stdout, ";   %s\n", MAIN.resconf.path[i]);
+
+	for (i = 0; i < MAIN.nssconf.count; i++)
+		fprintf(stdout, ";   %s\n", MAIN.nssconf.path[i]);
+
+	fputs(";\n", stdout);
+
+	dns_resconf_dump(resconf(), stdout);
+
+	return 0;
+} /* show_resconf() */
+
+
+static int show_nssconf(int argc DNS_NOTUSED, char *argv[] DNS_NOTUSED) {
+	unsigned i;
+
+	resconf();
+
+	fputs("# SOURCES\n", stdout);
+
+	for (i = 0; i < MAIN.resconf.count; i++)
+		fprintf(stdout, "#   %s\n", MAIN.resconf.path[i]);
+
+	for (i = 0; i < MAIN.nssconf.count; i++)
+		fprintf(stdout, "#   %s\n", MAIN.nssconf.path[i]);
+
+	fputs("#\n", stdout);
+
+	dns_nssconf_dump(resconf(), stdout);
+
+	return 0;
+} /* show_nssconf() */
+
+
+static int show_hosts(int argc DNS_NOTUSED, char *argv[] DNS_NOTUSED) {
+	unsigned i;
+
+	hosts();
+
+	fputs("# SOURCES\n", stdout);
+
+	for (i = 0; i < MAIN.hosts.count; i++)
+		fprintf(stdout, "#   %s\n", MAIN.hosts.path[i]);
+
+	fputs("#\n", stdout);
+
+	dns_hosts_dump(hosts(), stdout);
+
+	return 0;
+} /* show_hosts() */
+
+
+static int query_hosts(int argc, char *argv[]) {
+	struct dns_packet *Q	= dns_p_new(512);
+	struct dns_packet *A;
+	char qname[DNS_D_MAXNAME + 1];
+	size_t qlen;
+	int error;
+
+	if (!MAIN.qname)
+		MAIN.qname	= (argc > 1)? argv[1] : "localhost";
+	if (!MAIN.qtype)
+		MAIN.qtype	= DNS_T_A;
+
+	hosts();
+
+	if (MAIN.qtype == DNS_T_PTR && !strstr(MAIN.qname, "arpa")) {
+		union { struct in_addr a; struct in6_addr a6; } addr;
+		int af	= (strchr(MAIN.qname, ':'))? AF_INET6 : AF_INET;
+
+		if ((error = dns_pton(af, MAIN.qname, &addr)))
+			panic("%s: %s", MAIN.qname, dns_strerror(error));
+
+		qlen	= dns_ptr_qname(qname, sizeof qname, af, &addr);
+	} else
+		qlen	= dns_strlcpy(qname, MAIN.qname, sizeof qname);
+
+	if ((error = dns_p_push(Q, DNS_S_QD, qname, qlen, MAIN.qtype, DNS_C_IN, 0, 0)))
+		panic("%s: %s", qname, dns_strerror(error));
+
+	if (!(A = dns_hosts_query(hosts(), Q, &error)))
+		panic("%s: %s", qname, dns_strerror(error));
+
+	print_packet(A, stdout);
+
+	free(A);
+
+	return 0;
+} /* query_hosts() */
+
+
+static int search_list(int argc, char *argv[]) {
+	const char *qname	= (argc > 1)? argv[1] : "f.l.google.com";
+	unsigned long i		= 0;
+	char name[DNS_D_MAXNAME + 1];
+
+	printf("[%s]\n", qname);
+
+	while (dns_resconf_search(name, sizeof name, qname, strlen(qname), resconf(), &i))
+		puts(name);
+
+	return 0;
+} /* search_list() */
+
+
+static int permute_set(int argc, char *argv[]) {
+	unsigned lo, hi, i;
+	struct dns_k_permutor p;
+
+	hi	= (--argc > 0)? atoi(argv[argc]) : 8;
+	lo	= (--argc > 0)? atoi(argv[argc]) : 0;
+
+	fprintf(stderr, "[%u .. %u]\n", lo, hi);
+
+	dns_k_permutor_init(&p, lo, hi);
+
+	for (i = lo; i <= hi; i++)
+		fprintf(stdout, "%u\n", dns_k_permutor_step(&p));
+//		printf("%u -> %u -> %u\n", i, dns_k_permutor_E(&p, i), dns_k_permutor_D(&p, dns_k_permutor_E(&p, i)));
+
+	return 0;
+} /* permute_set() */
+
+
+static int shuffle_16(int argc, char *argv[]) {
+	unsigned n, r;
+
+	if (--argc > 0) {
+		n = 0xffff & atoi(argv[argc]);
+		r = (--argc > 0)? (unsigned)atoi(argv[argc]) : dns_random();
+
+		fprintf(stdout, "%hu\n", dns_k_shuffle16(n, r));
+	} else {
+		r = dns_random();
+
+		for (n = 0; n < 65536; n++)
+			fprintf(stdout, "%hu\n", dns_k_shuffle16(n, r));
+	}
+
+	return 0;
+} /* shuffle_16() */
+
+
+static int dump_random(int argc, char *argv[]) {
+	unsigned char b[32];
+	unsigned i, j, n, r;
+
+	n	= (argc > 1)? atoi(argv[1]) : 32;
+
+	while (n) {
+		i	= 0;
+
+		do {
+			r	= dns_random();
+
+			for (j = 0; j < sizeof r && i < n && i < sizeof b; i++, j++) {
+				b[i]	= 0xff & r;
+				r	>>= 8;
+			}
+		} while (i < n && i < sizeof b);
+
+		hexdump(b, i, stdout);
+
+		n	-= i;
+	}
+
+	return 0;
+} /* dump_random() */
+
+
+static int send_query(int argc, char *argv[]) {
+	struct dns_packet *A, *Q	= dns_p_new(512);
+	char host[INET6_ADDRSTRLEN + 1];
+	struct sockaddr_storage ss;
+	struct dns_socket *so;
+	int error, type;
+
+	if (argc > 1) {
+		ss.ss_family	= (strchr(argv[1], ':'))? AF_INET6 : AF_INET;
+
+		if ((error = dns_pton(ss.ss_family, argv[1], dns_sa_addr(ss.ss_family, &ss, NULL))))
+			panic("%s: %s", argv[1], dns_strerror(error));
+
+		*dns_sa_port(ss.ss_family, &ss)	= htons(53);
+	} else
+		memcpy(&ss, &resconf()->nameserver[0], dns_sa_len(&resconf()->nameserver[0]));
+
+	if (!dns_inet_ntop(ss.ss_family, dns_sa_addr(ss.ss_family, &ss, NULL), host, sizeof host))
+		panic("bad host address, or none provided");
+
+	if (!MAIN.qname)
+		MAIN.qname	= "ipv6.google.com";
+	if (!MAIN.qtype)
+		MAIN.qtype	= DNS_T_AAAA;
+
+	if ((error = dns_p_push(Q, DNS_S_QD, MAIN.qname, strlen(MAIN.qname), MAIN.qtype, DNS_C_IN, 0, 0)))
+		panic("dns_p_push: %s", dns_strerror(error));
+
+	dns_header(Q)->rd	= 1;
+
+	if (strstr(argv[0], "udp"))
+		type	= SOCK_DGRAM;
+	else if (strstr(argv[0], "tcp"))
+		type	= SOCK_STREAM;
+	else
+		type	= dns_res_tcp2type(resconf()->options.tcp);
+
+	fprintf(stderr, "querying %s for %s IN %s\n", host, MAIN.qname, dns_strtype(MAIN.qtype));
+
+	if (!(so = dns_so_open((struct sockaddr *)&resconf()->iface, type, dns_opts(), &error)))
+		panic("dns_so_open: %s", dns_strerror(error));
+
+	while (!(A = dns_so_query(so, Q, (struct sockaddr *)&ss, &error))) {
+		if (error != DNS_EAGAIN)
+			panic("dns_so_query: %s (%d)", dns_strerror(error), error);
+		if (dns_so_elapsed(so) > 10)
+			panic("query timed-out");
+
+		dns_so_poll(so, 1);
+	}
+
+	print_packet(A, stdout);
+
+	dns_so_close(so);
+
+	return 0;
+} /* send_query() */
+
+
+static int print_arpa(int argc, char *argv[]) {
+	const char *ip	= (argc > 1)? argv[1] : "::1";
+	int af		= (strchr(ip, ':'))? AF_INET6 : AF_INET;
+	union { struct in_addr a4; struct in6_addr a6; } addr;
+	char host[DNS_D_MAXNAME + 1];
+
+	if (1 != dns_inet_pton(af, ip, &addr) || 0 == dns_ptr_qname(host, sizeof host, af, &addr))
+		panic("%s: invalid address", ip);
+
+	fprintf(stdout, "%s\n", host);
+
+	return 0;
+} /* print_arpa() */
+
+
+static int show_hints(int argc, char *argv[]) {
+	struct dns_hints *(*load)(struct dns_resolv_conf *, int *);
+	const char *which, *how, *who;
+	struct dns_hints *hints;
+	int error;
+
+	which	= (argc > 1)? argv[1] : "local";
+	how	= (argc > 2)? argv[2] : "plain";
+	who	= (argc > 3)? argv[3] : "google.com";
+
+	load	= (0 == strcmp(which, "local"))
+		? &dns_hints_local
+		: &dns_hints_root;
+
+	if (!(hints = load(resconf(), &error)))
+		panic("%s: %s", argv[0], dns_strerror(error));
+
+	if (0 == strcmp(how, "plain")) {
+		dns_hints_dump(hints, stdout);
+	} else {
+		struct dns_packet *query, *answer;
+
+		query	= dns_p_new(512);
+
+		if ((error = dns_p_push(query, DNS_S_QUESTION, who, strlen(who), DNS_T_A, DNS_C_IN, 0, 0)))
+			panic("%s: %s", who, dns_strerror(error));
+
+		if (!(answer = dns_hints_query(hints, query, &error)))
+			panic("%s: %s", who, dns_strerror(error));
+
+		print_packet(answer, stdout);
+
+		free(answer);
+	}
+
+	dns_hints_close(hints);
+
+	return 0;
+} /* show_hints() */
+
+
+static int resolve_query(int argc DNS_NOTUSED, char *argv[]) {
+	_Bool recurse = !!strstr(argv[0], "recurse");
+	struct dns_hints *(*hints)() = (recurse)? &dns_hints_root : &dns_hints_local;
+	struct dns_resolver *R;
+	struct dns_packet *ans;
+	const struct dns_stat *st;
+	int error;
+
+	if (!MAIN.qname)
+		MAIN.qname = "www.google.com";
+	if (!MAIN.qtype)
+		MAIN.qtype = DNS_T_A;
+
+	resconf()->options.recurse = recurse;
+
+	if (!(R = dns_res_open(resconf(), hosts(), dns_hints_mortal(hints(resconf(), &error)), cache(),
+			       dns_opts(.socks_host=&MAIN.socks_host), &error)))
+		panic("%s: %s", MAIN.qname, dns_strerror(error));
+
+	dns_res_settrace(R, trace("w+b"));
+
+	if ((error = dns_res_submit(R, MAIN.qname, MAIN.qtype, DNS_C_IN)))
+		panic("%s: %s", MAIN.qname, dns_strerror(error));
+
+	while ((error = dns_res_check(R))) {
+		if (error != DNS_EAGAIN)
+			panic("dns_res_check: %s (%d)", dns_strerror(error), error);
+		if (dns_res_elapsed(R) > 30)
+			panic("query timed-out");
+
+		dns_res_poll(R, 1);
+	}
+
+	ans = dns_res_fetch(R, &error);
+	print_packet(ans, stdout);
+	free(ans);
+
+	st = dns_res_stat(R);
+	putchar('\n');
+	printf(";; queries:  %"PRIuZ"\n", st->queries);
+	printf(";; udp sent: %"PRIuZ" in %"PRIuZ" bytes\n", st->udp.sent.count, st->udp.sent.bytes);
+	printf(";; udp rcvd: %"PRIuZ" in %"PRIuZ" bytes\n", st->udp.rcvd.count, st->udp.rcvd.bytes);
+	printf(";; tcp sent: %"PRIuZ" in %"PRIuZ" bytes\n", st->tcp.sent.count, st->tcp.sent.bytes);
+	printf(";; tcp rcvd: %"PRIuZ" in %"PRIuZ" bytes\n", st->tcp.rcvd.count, st->tcp.rcvd.bytes);
+
+	dns_res_close(R);
+
+	return 0;
+} /* resolve_query() */
+
+
+static int resolve_addrinfo(int argc DNS_NOTUSED, char *argv[]) {
+	_Bool recurse = !!strstr(argv[0], "recurse");
+	struct dns_hints *(*hints)() = (recurse)? &dns_hints_root : &dns_hints_local;
+	struct dns_resolver *res = NULL;
+	struct dns_addrinfo *ai = NULL;
+	struct addrinfo ai_hints = { .ai_family = PF_UNSPEC, .ai_socktype = SOCK_STREAM, .ai_flags = AI_CANONNAME };
+	struct addrinfo *ent;
+	char pretty[512];
+	int error;
+
+	if (!MAIN.qname)
+		MAIN.qname = "www.google.com";
+	/* NB: MAIN.qtype of 0 means obey hints.ai_family */
+
+	resconf()->options.recurse = recurse;
+
+	if (!(res = dns_res_open(resconf(), hosts(), dns_hints_mortal(hints(resconf(), &error)), cache(), dns_opts(), &error)))
+		panic("%s: %s", MAIN.qname, dns_strerror(error));
+
+	if (!(ai = dns_ai_open(MAIN.qname, "80", MAIN.qtype, &ai_hints, res, &error)))
+		panic("%s: %s", MAIN.qname, dns_strerror(error));
+
+	dns_ai_settrace(ai, trace("w+b"));
+
+	do {
+		switch (error = dns_ai_nextent(&ent, ai)) {
+		case 0:
+			dns_ai_print(pretty, sizeof pretty, ent, ai);
+
+			fputs(pretty, stdout);
+
+			free(ent);
+
+			break;
+		case ENOENT:
+			break;
+		case DNS_EAGAIN:
+			if (dns_ai_elapsed(ai) > 30)
+				panic("query timed-out");
+
+			dns_ai_poll(ai, 1);
+
+			break;
+		default:
+			panic("dns_ai_nextent: %s (%d)", dns_strerror(error), error);
+		}
+	} while (error != ENOENT);
+
+	dns_res_close(res);
+	dns_ai_close(ai);
+
+	return 0;
+} /* resolve_addrinfo() */
+
+
+static int dump_trace(int argc DNS_NOTUSED, char *argv[]) {
+	int error;
+
+	if (!MAIN.trace)
+		panic("no trace file specified");
+
+	if ((error = dns_trace_dump(trace("r"), stdout)))
+		panic("dump_trace: %s", dns_strerror(error));
+
+	return 0;
+} /* dump_trace() */
+
+
+static int echo_port(int argc DNS_NOTUSED, char *argv[] DNS_NOTUSED) {
+	union {
+		struct sockaddr sa;
+		struct sockaddr_in sin;
+	} port;
+	int fd;
+
+	memset(&port, 0, sizeof port);
+	port.sin.sin_family = AF_INET;
+	port.sin.sin_port = htons(5354);
+	port.sin.sin_addr.s_addr = inet_addr("127.0.0.1");
+
+	if (-1 == (fd = socket(PF_INET, SOCK_DGRAM, 0)))
+		panic("socket: %s", strerror(errno));
+
+	if (0 != bind(fd, &port.sa, sizeof port.sa))
+		panic("127.0.0.1:5353: %s", dns_strerror(errno));
+
+	for (;;) {
+		struct dns_packet *pkt = dns_p_new(512);
+		struct sockaddr_storage ss;
+		socklen_t slen = sizeof ss;
+		ssize_t count;
+#if defined(MSG_WAITALL) /* MinGW issue */
+		int rflags = MSG_WAITALL;
+#else
+		int rflags = 0;
+#endif
+
+		count = recvfrom(fd, (char *)pkt->data, pkt->size, rflags, (struct sockaddr *)&ss, &slen);
+
+		if (!count || count < 0)
+			panic("recvfrom: %s", strerror(errno));
+
+		pkt->end = count;
+
+		dns_p_dump(pkt, stdout);
+
+		(void)sendto(fd, (char *)pkt->data, pkt->end, 0, (struct sockaddr *)&ss, slen);
+	}
+
+	return 0;
+} /* echo_port() */
+
+
+static int isection(int argc, char *argv[]) {
+	const char *name = (argc > 1)? argv[1] : "";
+	int type;
+
+	type = dns_isection(name);
+	name = dns_strsection(type);
+
+	printf("%s (%d)\n", name, type);
+
+	return 0;
+} /* isection() */
+
+
+static int iclass(int argc, char *argv[]) {
+	const char *name = (argc > 1)? argv[1] : "";
+	int type;
+
+	type = dns_iclass(name);
+	name = dns_strclass(type);
+
+	printf("%s (%d)\n", name, type);
+
+	return 0;
+} /* iclass() */
+
+
+static int itype(int argc, char *argv[]) {
+	const char *name = (argc > 1)? argv[1] : "";
+	int type;
+
+	type = dns_itype(name);
+	name = dns_strtype(type);
+
+	printf("%s (%d)\n", name, type);
+
+	return 0;
+} /* itype() */
+
+
+static int iopcode(int argc, char *argv[]) {
+	const char *name = (argc > 1)? argv[1] : "";
+	int type;
+
+	type = dns_iopcode(name);
+	name = dns_stropcode(type);
+
+	printf("%s (%d)\n", name, type);
+
+	return 0;
+} /* iopcode() */
+
+
+static int ircode(int argc, char *argv[]) {
+	const char *name = (argc > 1)? argv[1] : "";
+	int type;
+
+	type = dns_ircode(name);
+	name = dns_strrcode(type);
+
+	printf("%s (%d)\n", name, type);
+
+	return 0;
+} /* ircode() */
+
+
+#define SIZE1(x) { DNS_PP_STRINGIFY(x), sizeof (x) }
+#define SIZE2(x, ...) SIZE1(x), SIZE1(__VA_ARGS__)
+#define SIZE3(x, ...) SIZE1(x), SIZE2(__VA_ARGS__)
+#define SIZE4(x, ...) SIZE1(x), SIZE3(__VA_ARGS__)
+#define SIZE(...) DNS_PP_CALL(DNS_PP_XPASTE(SIZE, DNS_PP_NARG(__VA_ARGS__)), __VA_ARGS__)
+
+static int sizes(int argc DNS_NOTUSED, char *argv[] DNS_NOTUSED) {
+	static const struct { const char *name; size_t size; } type[] = {
+		SIZE(struct dns_header, struct dns_packet, struct dns_rr, struct dns_rr_i),
+		SIZE(struct dns_a, struct dns_aaaa, struct dns_mx, struct dns_ns),
+		SIZE(struct dns_cname, struct dns_soa, struct dns_ptr, struct dns_srv),
+		SIZE(struct dns_sshfp, struct dns_txt, union dns_any),
+		SIZE(struct dns_resolv_conf, struct dns_hosts, struct dns_hints, struct dns_hints_i),
+		SIZE(struct dns_options, struct dns_socket, struct dns_resolver, struct dns_addrinfo),
+		SIZE(struct dns_cache), SIZE(size_t), SIZE(void *), SIZE(long)
+	};
+	unsigned i, max;
+
+	for (i = 0, max = 0; i < lengthof(type); i++)
+		max = DNS_PP_MAX(max, strlen(type[i].name));
+
+	for (i = 0; i < lengthof(type); i++)
+		printf("%*s : %"PRIuZ"\n", max, type[i].name, type[i].size);
+
+	return 0;
+} /* sizes() */
+
+
+static const struct { const char *cmd; int (*run)(); const char *help; } cmds[] = {
+	{ "parse-packet",	&parse_packet,		"parse binary packet from stdin" },
+	{ "parse-domain",	&parse_domain,		"anchor and iteratively cleave domain" },
+	{ "trim-domain",	&trim_domain,		"trim and anchor domain name" },
+	{ "expand-domain",	&expand_domain,		"expand domain at offset NN in packet from stdin" },
+	{ "show-resconf",	&show_resconf,		"show resolv.conf data" },
+	{ "show-hosts",		&show_hosts,		"show hosts data" },
+	{ "show-nssconf",	&show_nssconf,		"show nsswitch.conf data" },
+	{ "query-hosts",	&query_hosts,		"query A, AAAA or PTR in hosts data" },
+	{ "search-list",	&search_list,		"generate query search list from domain" },
+	{ "permute-set",	&permute_set,		"generate random permutation -> (0 .. N or N .. M)" },
+	{ "shuffle-16",		&shuffle_16,		"simple 16-bit permutation" },
+	{ "dump-random",	&dump_random,		"generate random bytes" },
+	{ "send-query",		&send_query,		"send query to host" },
+	{ "send-query-udp",	&send_query,		"send udp query to host" },
+	{ "send-query-tcp",	&send_query,		"send tcp query to host" },
+	{ "print-arpa",		&print_arpa,		"print arpa. zone name of address" },
+	{ "show-hints",		&show_hints,		"print hints: show-hints [local|root] [plain|packet]" },
+	{ "resolve-stub",	&resolve_query,		"resolve as stub resolver" },
+	{ "resolve-recurse",	&resolve_query,		"resolve as recursive resolver" },
+	{ "addrinfo-stub",	&resolve_addrinfo,	"resolve through getaddrinfo clone" },
+	{ "addrinfo-recurse",	&resolve_addrinfo,	"resolve through getaddrinfo clone" },
+/*	{ "resolve-nameinfo",	&resolve_query,		"resolve as recursive resolver" }, */
+	{ "dump-trace",         &dump_trace,            "dump the contents of a trace file" },
+	{ "echo",		&echo_port,		"server echo mode, for nmap fuzzing" },
+	{ "isection",		&isection,		"parse section string" },
+	{ "iclass",		&iclass,		"parse class string" },
+	{ "itype",		&itype,			"parse type string" },
+	{ "iopcode",		&iopcode,		"parse opcode string" },
+	{ "ircode",		&ircode,		"parse rcode string" },
+	{ "sizes",		&sizes,			"print data structure sizes" },
+};
+
+
+static void print_usage(const char *progname, FILE *fp) {
+	static const char *usage	=
+		" [OPTIONS] COMMAND [ARGS]\n"
+		"  -c PATH   Path to resolv.conf\n"
+		"  -n PATH   Path to nsswitch.conf\n"
+		"  -l PATH   Path to local hosts\n"
+		"  -z PATH   Path to zone cache\n"
+		"  -q QNAME  Query name\n"
+		"  -t QTYPE  Query type\n"
+		"  -s HOW    Sort records\n"
+		"  -S ADDR   Address of SOCKS server to use\n"
+		"  -P PORT   Port of SOCKS server to use\n"
+		"  -f PATH   Path to trace file\n"
+		"  -v        Be more verbose (-vv show packets; -vvv hexdump packets)\n"
+		"  -V        Print version info\n"
+		"  -h        Print this usage message\n"
+		"\n";
+	unsigned i, n, m;
+
+	fputs(progname, fp);
+	fputs(usage, fp);
+
+	for (i = 0, m = 0; i < lengthof(cmds); i++) {
+		if (strlen(cmds[i].cmd) > m)
+			m	= strlen(cmds[i].cmd);
+	}
+
+	for (i = 0; i < lengthof(cmds); i++) {
+		fprintf(fp, "  %s  ", cmds[i].cmd);
+
+		for (n = strlen(cmds[i].cmd); n < m; n++)
+			putc(' ', fp);
+
+		fputs(cmds[i].help, fp);
+		putc('\n', fp);
+	}
+
+	fputs("\nReport bugs to William Ahern <william@25thandClement.com>\n", fp);
+} /* print_usage() */
+
+
+static void print_version(const char *progname, FILE *fp) {
+	fprintf(fp, "%s (dns.c) %.8X\n", progname, dns_v_rel());
+	fprintf(fp, "vendor  %s\n", dns_vendor());
+	fprintf(fp, "release %.8X\n", dns_v_rel());
+	fprintf(fp, "abi     %.8X\n", dns_v_abi());
+	fprintf(fp, "api     %.8X\n", dns_v_api());
+} /* print_version() */
+
+
+static void main_exit(void) {
+	dns_trace_close(MAIN.memo.trace);
+	MAIN.memo.trace = NULL;
+	dns_hosts_close(MAIN.memo.hosts);
+	MAIN.memo.hosts = NULL;
+	dns_resconf_close(MAIN.memo.resconf);
+	MAIN.memo.resconf = NULL;
+} /* main_exit() */
+
+int main(int argc, char **argv) {
+	extern int optind;
+	extern char *optarg;
+	const char *progname	= argv[0];
+	unsigned i;
+	int ch;
+
+	atexit(&main_exit);
+
+	while (-1 != (ch = getopt(argc, argv, "q:t:c:n:l:z:s:S:P:f:vVh"))) {
+		switch (ch) {
+		case 'c':
+			assert(MAIN.resconf.count < lengthof(MAIN.resconf.path));
+
+			MAIN.resconf.path[MAIN.resconf.count++]	= optarg;
+
+			break;
+		case 'n':
+			assert(MAIN.nssconf.count < lengthof(MAIN.nssconf.path));
+
+			MAIN.nssconf.path[MAIN.nssconf.count++]	= optarg;
+
+			break;
+		case 'l':
+			assert(MAIN.hosts.count < lengthof(MAIN.hosts.path));
+
+			MAIN.hosts.path[MAIN.hosts.count++]	= optarg;
+
+			break;
+		case 'z':
+			assert(MAIN.cache.count < lengthof(MAIN.cache.path));
+
+			MAIN.cache.path[MAIN.cache.count++]	= optarg;
+
+			break;
+		case 'q':
+			MAIN.qname	= optarg;
+
+			break;
+		case 't':
+			for (i = 0; i < lengthof(dns_rrtypes); i++) {
+				if (0 == strcasecmp(dns_rrtypes[i].name, optarg))
+					{ MAIN.qtype = dns_rrtypes[i].type; break; }
+			}
+
+			if (MAIN.qtype)
+				break;
+
+			for (i = 0; dns_isdigit(optarg[i]); i++) {
+				MAIN.qtype	*= 10;
+				MAIN.qtype	+= optarg[i] - '0';
+			}
+
+			if (!MAIN.qtype)
+				panic("%s: invalid query type", optarg);
+
+			break;
+		case 's':
+			if (0 == strcasecmp(optarg, "packet"))
+				MAIN.sort	= &dns_rr_i_packet;
+			else if (0 == strcasecmp(optarg, "shuffle"))
+				MAIN.sort	= &dns_rr_i_shuffle;
+			else if (0 == strcasecmp(optarg, "order"))
+				MAIN.sort	= &dns_rr_i_order;
+			else
+				panic("%s: invalid sort method", optarg);
+
+			break;
+		case 'S': {
+			dns_error_t error;
+			struct dns_resolv_conf *conf = resconf();
+			conf->options.tcp = DNS_RESCONF_TCP_SOCKS;
+
+			MAIN.socks_host.ss_family = (strchr(optarg, ':')) ? AF_INET6 : AF_INET;
+			if ((error = dns_pton(MAIN.socks_host.ss_family, optarg,
+					      dns_sa_addr(MAIN.socks_host.ss_family,
+							  &MAIN.socks_host, NULL))))
+				panic("%s: %s", optarg, dns_strerror(error));
+
+			*dns_sa_port(MAIN.socks_host.ss_family, &MAIN.socks_host) = htons(1080);
+
+			break;
+		}
+		case 'P':
+			if (! MAIN.socks_host.ss_family)
+				panic("-P without prior -S");
+			*dns_sa_port(MAIN.socks_host.ss_family, &MAIN.socks_host) = htons(atoi(optarg));
+
+			break;
+		case 'f':
+			MAIN.trace = optarg;
+
+			break;
+		case 'v':
+			dns_debug = ++MAIN.verbose;
+
+			break;
+		case 'V':
+			print_version(progname, stdout);
+
+			return 0;
+		case 'h':
+			print_usage(progname, stdout);
+
+			return 0;
+		default:
+			print_usage(progname, stderr);
+
+			return EXIT_FAILURE;
+		} /* switch() */
+	} /* while() */
+
+	argc	-= optind;
+	argv	+= optind;
+
+	for (i = 0; i < lengthof(cmds) && argv[0]; i++) {
+		if (0 == strcmp(cmds[i].cmd, argv[0]))
+			return cmds[i].run(argc, argv);
+	}
+
+	print_usage(progname, stderr);
+
+	return EXIT_FAILURE;
+} /* main() */
+
+
+#endif /* DNS_MAIN */
+
+
+/*
+ * pop file-scoped compiler annotations
+ */
+#if __clang__
+#pragma clang diagnostic pop
+#elif DNS_GNUC_PREREQ(4,6,0)
+#pragma GCC diagnostic pop
+#endif