path: root/lib/vty.c

/*
 * Virtual terminal [aka TeletYpe] interface routine.
 * Copyright (C) 1997, 98 Kunihiro Ishiguro
 *
 * This file is part of GNU Zebra.
 *
 * GNU Zebra is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by the
 * Free Software Foundation; either version 2, or (at your option) any
 * later version.
 *
 * GNU Zebra is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program; see the file COPYING; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
 */

#include <zebra.h>

#include <lib/version.h>
#include <sys/types.h>
#include <sys/types.h>
#ifdef HAVE_LIBPCREPOSIX
#include <pcreposix.h>
#else
#include <regex.h>
#endif /* HAVE_LIBPCREPOSIX */
#include <stdio.h>

#include "linklist.h"
#include "thread.h"
#include "buffer.h"
#include "command.h"
#include "sockunion.h"
#include "memory.h"
#include "log.h"
#include "prefix.h"
#include "filter.h"
#include "vty.h"
#include "privs.h"
#include "network.h"
#include "libfrr.h"
#include "frrstr.h"
#include "lib_errors.h"
#include "northbound_cli.h"
#include "printfrr.h"

#include <arpa/telnet.h>
#include <termios.h>

#ifndef VTYSH_EXTRACT_PL
#include "lib/vty_clippy.c"
#endif

DEFINE_MTYPE_STATIC(LIB, VTY, "VTY")
DEFINE_MTYPE_STATIC(LIB, VTY_OUT_BUF, "VTY output buffer")
DEFINE_MTYPE_STATIC(LIB, VTY_HIST, "VTY history")

/* Vty events */
enum event {
	VTY_SERV,
	VTY_READ,
	VTY_WRITE,
	VTY_TIMEOUT_RESET,
#ifdef VTYSH
	VTYSH_SERV,
	VTYSH_READ,
	VTYSH_WRITE
#endif /* VTYSH */
};

static void vty_event(enum event, int, struct vty *);

/* Extern host structure from command.c */
extern struct host host;

/* Vector which store each vty structure. */
static vector vtyvec;

/* Vty timeout value. */
static unsigned long vty_timeout_val = VTY_TIMEOUT_DEFAULT;

/* Vty access-class command */
static char *vty_accesslist_name = NULL;

/* Vty access-calss for IPv6. */
static char *vty_ipv6_accesslist_name = NULL;

/* VTY server thread. */
static vector Vvty_serv_thread;

/* Current directory. */
static char vty_cwd[MAXPATHLEN];

/* Login password check. */
static int no_password_check = 0;

/* Integrated configuration file path */
static char integrate_default[] = SYSCONFDIR INTEGRATE_DEFAULT_CONFIG;

static bool do_log_commands;
static bool do_log_commands_perm;

void vty_frame(struct vty *vty, const char *format, ...)
{
	va_list args;

	va_start(args, format);
	vsnprintfrr(vty->frame + vty->frame_pos,
		    sizeof(vty->frame) - vty->frame_pos, format, args);
	vty->frame_pos = strlen(vty->frame);
	va_end(args);
}

void vty_endframe(struct vty *vty, const char *endtext)
{
	if (vty->frame_pos == 0 && endtext)
		vty_out(vty, "%s", endtext);
	vty->frame_pos = 0;
}

bool vty_set_include(struct vty *vty, const char *regexp)
{
	int errcode;
	bool ret = true;
	char errbuf[256];

	if (!regexp) {
		if (vty->filter) {
			regfree(&vty->include);
			vty->filter = false;
		}
		return true;
	}

	errcode = regcomp(&vty->include, regexp,
			  REG_EXTENDED | REG_NEWLINE | REG_NOSUB);
	if (errcode) {
		ret = false;
		regerror(ret, &vty->include, errbuf, sizeof(errbuf));
		vty_out(vty, "%% Regex compilation error: %s", errbuf);
	} else {
		vty->filter = true;
	}

	return ret;
}

/* VTY standard output function. */
int vty_out(struct vty *vty, const char *format, ...)
{
	va_list args;
	ssize_t len;
	char buf[1024];
	char *p = NULL;
	char *filtered;

	if (vty->frame_pos) {
		vty->frame_pos = 0;
		vty_out(vty, "%s", vty->frame);
	}

	va_start(args, format);
	p = vasnprintfrr(MTYPE_VTY_OUT_BUF, buf, sizeof(buf), format, args);
	va_end(args);

	len = strlen(p);

	/* filter buffer */
	if (vty->filter) {
		vector lines = frrstr_split_vec(p, "\n");

		/* Place first value in the cache */
		char *firstline = vector_slot(lines, 0);
		buffer_put(vty->lbuf, (uint8_t *) firstline, strlen(firstline));

		/* If our split returned more than one entry, time to filter */
		if (vector_active(lines) > 1) {
			/*
			 * returned string is MTYPE_TMP so it matches the MTYPE
			 * of everything else in the vector
			 */
			char *bstr = buffer_getstr(vty->lbuf);
			buffer_reset(vty->lbuf);
			XFREE(MTYPE_TMP, lines->index[0]);
			vector_set_index(lines, 0, bstr);
			frrstr_filter_vec(lines, &vty->include);
			vector_compact(lines);
			/*
			 * Consider the string "foo\n". If the regex is an empty string
			 * and the line ended with a newline, then the vector will look
			 * like:
			 *
			 * [0]: 'foo'
			 * [1]: ''
			 *
			 * If the regex isn't empty, the vector will look like:
			 *
			 * [0]: 'foo'
			 *
			 * In this case we'd like to preserve the newline, so we add
			 * the empty string [1] as in the first example.
			 */
			if (p[strlen(p) - 1] == '\n' && vector_active(lines) > 0
			    && strlen(vector_slot(lines, vector_active(lines) - 1)))
				vector_set(lines, XSTRDUP(MTYPE_TMP, ""));

			filtered = frrstr_join_vec(lines, "\n");
		}
		else {
			filtered = NULL;
		}

		frrstr_strvec_free(lines);

	} else {
		filtered = p;
	}

	if (!filtered)
		goto done;

	switch (vty->type) {
	case VTY_TERM:
		/* print with crlf replacement */
		buffer_put_crlf(vty->obuf, (uint8_t *)filtered,
				strlen(filtered));
		break;
	case VTY_SHELL:
		if (vty->of) {
			fprintf(vty->of, "%s", filtered);
			fflush(vty->of);
		} else if (vty->of_saved) {
			fprintf(vty->of_saved, "%s", filtered);
			fflush(vty->of_saved);
		}
		break;
	case VTY_SHELL_SERV:
	case VTY_FILE:
	default:
		/* print without crlf replacement */
		buffer_put(vty->obuf, (uint8_t *)filtered, strlen(filtered));
		break;
	}

done:

	if (vty->filter && filtered)
		XFREE(MTYPE_TMP, filtered);

	/* If p is not different with buf, it is allocated buffer.  */
	if (p != buf)
		XFREE(MTYPE_VTY_OUT_BUF, p);

	return len;
}

static int vty_log_out(struct vty *vty, const char *level,
		       const char *proto_str, const char *msg,
		       struct timestamp_control *ctl)
{
	int ret;
	int len;
	char buf[1024];

	if (!ctl->already_rendered) {
		ctl->len = quagga_timestamp(ctl->precision, ctl->buf,
					    sizeof(ctl->buf));
		ctl->already_rendered = 1;
	}
	if (ctl->len + 1 >= sizeof(buf))
		return -1;
	memcpy(buf, ctl->buf, len = ctl->len);
	buf[len++] = ' ';
	buf[len] = '\0';

	if (level)
		ret = snprintf(buf + len, sizeof(buf) - len, "%s: %s: ", level,
			       proto_str);
	else
		ret = snprintf(buf + len, sizeof(buf) - len, "%s: ", proto_str);
	if ((ret < 0) || ((size_t)(len += ret) >= sizeof(buf)))
		return -1;

	if (((ret = snprintf(buf + len, sizeof(buf) - len, "%s", msg)) < 0)
	    || ((size_t)((len += ret) + 2) > sizeof(buf)))
		return -1;

	buf[len++] = '\r';
	buf[len++] = '\n';

	if (write(vty->wfd, buf, len) < 0) {
		if (ERRNO_IO_RETRY(errno))
			/* Kernel buffer is full, probably too much debugging
			   output, so just
			   drop the data and ignore. */
			return -1;
		/* Fatal I/O error. */
		vty->monitor =
			0; /* disable monitoring to avoid infinite recursion */
		flog_err(EC_LIB_SOCKET,
			 "%s: write failed to vty client fd %d, closing: %s",
			 __func__, vty->fd, safe_strerror(errno));
		buffer_reset(vty->obuf);
		buffer_reset(vty->lbuf);
		/* cannot call vty_close, because a parent routine may still try
		   to access the vty struct */
		vty->status = VTY_CLOSE;
		shutdown(vty->fd, SHUT_RDWR);
		return -1;
	}
	return 0;
}

/* Output current time to the vty. */
void vty_time_print(struct vty *vty, int cr)
{
	char buf[QUAGGA_TIMESTAMP_LEN];

	if (quagga_timestamp(0, buf, sizeof(buf)) == 0) {
		zlog_info("quagga_timestamp error");
		return;
	}
	if (cr)
		vty_out(vty, "%s\n", buf);
	else
		vty_out(vty, "%s ", buf);

	return;
}

/* Say hello to vty interface. */
void vty_hello(struct vty *vty)
{
	if (host.motdfile) {
		FILE *f;
		char buf[4096];

		f = fopen(host.motdfile, "r");
		if (f) {
			while (fgets(buf, sizeof(buf), f)) {
				char *s;
				/* work backwards to ignore trailling isspace()
				 */
				for (s = buf + strlen(buf);
				     (s > buf) && isspace((unsigned char)s[-1]);
				     s--)
					;
				*s = '\0';
				vty_out(vty, "%s\n", buf);
			}
			fclose(f);
		} else
			vty_out(vty, "MOTD file not found\n");
	} else if (host.motd)
		vty_out(vty, "%s", host.motd);

#if CONFDATE > 20200901
	CPP_NOTICE("Please remove solaris code from system as it is deprecated");
#endif
#ifdef SUNOS_5
	zlog_warn("If you are using FRR on Solaris, the FRR developers would love to hear from you\n");
	zlog_warn("Please send email to dev@lists.frrouting.org about this message\n");
	zlog_warn("We are considering deprecating Solaris and want to find users of Solaris systems\n");
#endif
}

/* Put out prompt and wait input from user. */
static void vty_prompt(struct vty *vty)
{
	if (vty->type == VTY_TERM) {
		vty_out(vty, cmd_prompt(vty->node), cmd_hostname_get());
	}
}

/* Send WILL TELOPT_ECHO to remote server. */
static void vty_will_echo(struct vty *vty)
{
	unsigned char cmd[] = {IAC, WILL, TELOPT_ECHO, '\0'};
	vty_out(vty, "%s", cmd);
}

/* Make suppress Go-Ahead telnet option. */
static void vty_will_suppress_go_ahead(struct vty *vty)
{
	unsigned char cmd[] = {IAC, WILL, TELOPT_SGA, '\0'};
	vty_out(vty, "%s", cmd);
}

/* Make don't use linemode over telnet. */
static void vty_dont_linemode(struct vty *vty)
{
	unsigned char cmd[] = {IAC, DONT, TELOPT_LINEMODE, '\0'};
	vty_out(vty, "%s", cmd);
}

/* Use window size. */
static void vty_do_window_size(struct vty *vty)
{
	unsigned char cmd[] = {IAC, DO, TELOPT_NAWS, '\0'};
	vty_out(vty, "%s", cmd);
}

#if 0  /* Currently not used. */
/* Make don't use lflow vty interface. */
static void
vty_dont_lflow_ahead (struct vty *vty)
{
  unsigned char cmd[] = { IAC, DONT, TELOPT_LFLOW, '\0' };
  vty_out (vty, "%s", cmd);
}
#endif /* 0 */

/* Authentication of vty */
static void vty_auth(struct vty *vty, char *buf)
{
	char *passwd = NULL;
	enum node_type next_node = 0;
	int fail;
	char *crypt(const char *, const char *);

	switch (vty->node) {
	case AUTH_NODE:
		if (host.encrypt)
			passwd = host.password_encrypt;
		else
			passwd = host.password;
		if (host.advanced)
			next_node = host.enable ? VIEW_NODE : ENABLE_NODE;
		else
			next_node = VIEW_NODE;
		break;
	case AUTH_ENABLE_NODE:
		if (host.encrypt)
			passwd = host.enable_encrypt;
		else
			passwd = host.enable;
		next_node = ENABLE_NODE;
		break;
	}

	if (passwd) {
		if (host.encrypt)
			fail = strcmp(crypt(buf, passwd), passwd);
		else
			fail = strcmp(buf, passwd);
	} else
		fail = 1;

	if (!fail) {
		vty->fail = 0;
		vty->node = next_node; /* Success ! */
	} else {
		vty->fail++;
		if (vty->fail >= 3) {
			if (vty->node == AUTH_NODE) {
				vty_out(vty,
					"%% Bad passwords, too many failures!\n");
				vty->status = VTY_CLOSE;
			} else {
				/* AUTH_ENABLE_NODE */
				vty->fail = 0;
				vty_out(vty,
					"%% Bad enable passwords, too many failures!\n");
				vty->status = VTY_CLOSE;
			}
		}
	}
}

/* Command execution over the vty interface. */
static int vty_command(struct vty *vty, char *buf)
{
	int ret;
	const char *protocolname;
	char *cp = NULL;

	assert(vty);

	/*
	 * Log non empty command lines
	 */
	if (do_log_commands)
		cp = buf;
	if (cp != NULL) {
		/* Skip white spaces. */
		while (isspace((unsigned char)*cp) && *cp != '\0')
			cp++;
	}
	if (cp != NULL && *cp != '\0') {
		unsigned i;
		char vty_str[VTY_BUFSIZ];
		char prompt_str[VTY_BUFSIZ];

		/* format the base vty info */
		snprintf(vty_str, sizeof(vty_str), "vty[??]@%s", vty->address);

		for (i = 0; i < vector_active(vtyvec); i++)
			if (vty == vector_slot(vtyvec, i)) {
				snprintf(vty_str, sizeof(vty_str), "vty[%d]@%s",
					 i, vty->address);
				break;
			}

		/* format the prompt */
		snprintf(prompt_str, sizeof(prompt_str), cmd_prompt(vty->node),
			 vty_str);

		/* now log the command */
		zlog_notice("%s%s", prompt_str, buf);
	}

#ifdef CONSUMED_TIME_CHECK
	{
		RUSAGE_T before;
		RUSAGE_T after;
		unsigned long realtime, cputime;

		GETRUSAGE(&before);
#endif /* CONSUMED_TIME_CHECK */

		ret = cmd_execute(vty, buf, NULL, 0);

		/* Get the name of the protocol if any */
		protocolname = frr_protoname;

#ifdef CONSUMED_TIME_CHECK
		GETRUSAGE(&after);
		if ((realtime = thread_consumed_time(&after, &before, &cputime))
		    > CONSUMED_TIME_CHECK)
			/* Warn about CPU hog that must be fixed. */
			flog_warn(
				EC_LIB_SLOW_THREAD,
				"SLOW COMMAND: command took %lums (cpu time %lums): %s",
				realtime / 1000, cputime / 1000, buf);
	}
#endif /* CONSUMED_TIME_CHECK */

	if (ret != CMD_SUCCESS)
		switch (ret) {
		case CMD_WARNING:
			if (vty->type == VTY_FILE)
				vty_out(vty, "Warning...\n");
			break;
		case CMD_ERR_AMBIGUOUS:
			vty_out(vty, "%% Ambiguous command.\n");
			break;
		case CMD_ERR_NO_MATCH:
			vty_out(vty, "%% [%s] Unknown command: %s\n",
				protocolname, buf);
			break;
		case CMD_ERR_INCOMPLETE:
			vty_out(vty, "%% Command incomplete.\n");
			break;
		}

	return ret;
}

static const char telnet_backward_char = 0x08;
static const char telnet_space_char = ' ';

/* Basic function to write buffer to vty. */
static void vty_write(struct vty *vty, const char *buf, size_t nbytes)
{
	if ((vty->node == AUTH_NODE) || (vty->node == AUTH_ENABLE_NODE))
		return;

	/* Should we do buffering here ?  And make vty_flush (vty) ? */
	buffer_put(vty->obuf, buf, nbytes);
}

/* Basic function to insert character into vty. */
static void vty_self_insert(struct vty *vty, char c)
{
	int i;
	int length;

	if (vty->length + 1 >= VTY_BUFSIZ)
		return;

	length = vty->length - vty->cp;
	memmove(&vty->buf[vty->cp + 1], &vty->buf[vty->cp], length);
	vty->buf[vty->cp] = c;

	vty_write(vty, &vty->buf[vty->cp], length + 1);
	for (i = 0; i < length; i++)
		vty_write(vty, &telnet_backward_char, 1);

	vty->cp++;
	vty->length++;

	vty->buf[vty->length] = '\0';
}

/* Self insert character 'c' in overwrite mode. */
static void vty_self_insert_overwrite(struct vty *vty, char c)
{
	if (vty->cp == vty->length) {
		vty_self_insert(vty, c);
		return;
	}

	vty->buf[vty->cp++] = c;
	vty_write(vty, &c, 1);
}

/**
 * Insert a string into vty->buf at the current cursor position.
 *
 * If the resultant string would be larger than VTY_BUFSIZ it is
 * truncated to fit.
 */
static void vty_insert_word_overwrite(struct vty *vty, char *str)
{
	if (vty->cp == VTY_BUFSIZ)
		return;

	size_t nwrite = MIN((int)strlen(str), VTY_BUFSIZ - vty->cp - 1);
	memcpy(&vty->buf[vty->cp], str, nwrite);
	vty->cp += nwrite;
	vty->length = MAX(vty->cp, vty->length);
	vty->buf[vty->length] = '\0';
	vty_write(vty, str, nwrite);
}

/* Forward character. */
static void vty_forward_char(struct vty *vty)
{
	if (vty->cp < vty->length) {
		vty_write(vty, &vty->buf[vty->cp], 1);
		vty->cp++;
	}
}

/* Backward character. */
static void vty_backward_char(struct vty *vty)
{
	if (vty->cp > 0) {
		vty->cp--;
		vty_write(vty, &telnet_backward_char, 1);
	}
}

/* Move to the beginning of the line. */
static void vty_beginning_of_line(struct vty *vty)
{
	while (vty->cp)
		vty_backward_char(vty);
}

/* Move to the end of the line. */
static void vty_end_of_line(struct vty *vty)
{
	while (vty->cp < vty->length)
		vty_forward_char(vty);
}

static void vty_kill_line_from_beginning(struct vty *);
static void vty_redraw_line(struct vty *);

/* Print command line history.  This function is called from
   vty_next_line and vty_previous_line. */
static void vty_history_print(struct vty *vty)
{
	int length;

	vty_kill_line_from_beginning(vty);

	/* Get previous line from history buffer */
	length = strlen(vty->hist[vty->hp]);
	memcpy(vty->buf, vty->hist[vty->hp], length);
	vty->cp = vty->length = length;
	vty->buf[vty->length] = '\0';

	/* Redraw current line */
	vty_redraw_line(vty);
}

/* Show next command line history. */
static void vty_next_line(struct vty *vty)
{
	int try_index;

	if (vty->hp == vty->hindex)
		return;

	/* Try is there history exist or not. */
	try_index = vty->hp;
	if (try_index == (VTY_MAXHIST - 1))
		try_index = 0;
	else
		try_index++;

	/* If there is not history return. */
	if (vty->hist[try_index] == NULL)
		return;
	else
		vty->hp = try_index;

	vty_history_print(vty);
}

/* Show previous command line history. */
static void vty_previous_line(struct vty *vty)
{
	int try_index;

	try_index = vty->hp;
	if (try_index == 0)
		try_index = VTY_MAXHIST - 1;
	else
		try_index--;

	if (vty->hist[try_index] == NULL)
		return;
	else
		vty->hp = try_index;

	vty_history_print(vty);
}

/* This function redraw all of the command line character. */
static void vty_redraw_line(struct vty *vty)
{
	vty_write(vty, vty->buf, vty->length);
	vty->cp = vty->length;
}

/* Forward word. */
static void vty_forward_word(struct vty *vty)
{
	while (vty->cp != vty->length && vty->buf[vty->cp] != ' ')
		vty_forward_char(vty);

	while (vty->cp != vty->length && vty->buf[vty->cp] == ' ')
		vty_forward_char(vty);
}

/* Backward word without skipping training space. */
static void vty_backward_pure_word(struct vty *vty)
{
	while (vty->cp > 0 && vty->buf[vty->cp - 1] != ' ')
		vty_backward_char(vty);
}

/* Backward word. */
static void vty_backward_word(struct vty *vty)
{
	while (vty->cp > 0 && vty->buf[vty->cp - 1] == ' ')
		vty_backward_char(vty);

	while (vty->cp > 0 && vty->buf[vty->cp - 1] != ' ')
		vty_backward_char(vty);
}

/* When '^D' is typed at the beginning of the line we move to the down
   level. */
static void vty_down_level(struct vty *vty)
{
	vty_out(vty, "\n");
	cmd_exit(vty);
	vty_prompt(vty);
	vty->cp = 0;
}

/* When '^Z' is received from vty, move down to the enable mode. */
static void vty_end_config(struct vty *vty)
{
	vty_out(vty, "\n");

	if (vty->config) {
		vty_config_exit(vty);
		vty->node = ENABLE_NODE;
	}

	vty_prompt(vty);
	vty->cp = 0;
}

/* Delete a charcter at the current point. */
static void vty_delete_char(struct vty *vty)
{
	int i;
	int size;

	if (vty->length == 0) {
		vty_down_level(vty);
		return;
	}

	if (vty->cp == vty->length)
		return; /* completion need here? */

	size = vty->length - vty->cp;

	vty->length--;
	memmove(&vty->buf[vty->cp], &vty->buf[vty->cp + 1], size - 1);
	vty->buf[vty->length] = '\0';

	if (vty->node == AUTH_NODE || vty->node == AUTH_ENABLE_NODE)
		return;

	vty_write(vty, &vty->buf[vty->cp], size - 1);
	vty_write(vty, &telnet_space_char, 1);

	for (i = 0; i < size; i++)
		vty_write(vty, &telnet_backward_char, 1);
}

/* Delete a character before the point. */
static void vty_delete_backward_char(struct vty *vty)
{
	if (vty->cp == 0)
		return;

	vty_backward_char(vty);
	vty_delete_char(vty);
}

/* Kill rest of line from current point. */
static void vty_kill_line(struct vty *vty)
{
	int i;
	int size;

	size = vty->length - vty->cp;

	if (size == 0)
		return;

	for (i = 0; i < size; i++)
		vty_write(vty, &telnet_space_char, 1);
	for (i = 0; i < size; i++)
		vty_write(vty, &telnet_backward_char, 1);

	memset(&vty->buf[vty->cp], 0, size);
	vty->length = vty->cp;
}

/* Kill line from the beginning. */
static void vty_kill_line_from_beginning(struct vty *vty)
{
	vty_beginning_of_line(vty);
	vty_kill_line(vty);
}

/* Delete a word before the point. */
static void vty_forward_kill_word(struct vty *vty)
{
	while (vty->cp != vty->length && vty->buf[vty->cp] == ' ')
		vty_delete_char(vty);
	while (vty->cp != vty->length && vty->buf[vty->cp] != ' ')
		vty_delete_char(vty);
}

/* Delete a word before the point. */
static void vty_backward_kill_word(struct vty *vty)
{
	while (vty->cp > 0 && vty->buf[vty->cp - 1] == ' ')
		vty_delete_backward_char(vty);
	while (vty->cp > 0 && vty->buf[vty->cp - 1] != ' ')
		vty_delete_backward_char(vty);
}

/* Transpose chars before or at the point. */
static void vty_transpose_chars(struct vty *vty)
{
	char c1, c2;

	/* If length is short or point is near by the beginning of line then
	   return. */
	if (vty->length < 2 || vty->cp < 1)
		return;

	/* In case of point is located at the end of the line. */
	if (vty->cp == vty->length) {
		c1 = vty->buf[vty->cp - 1];
		c2 = vty->buf[vty->cp - 2];

		vty_backward_char(vty);
		vty_backward_char(vty);
		vty_self_insert_overwrite(vty, c1);
		vty_self_insert_overwrite(vty, c2);
	} else {
		c1 = vty->buf[vty->cp];
		c2 = vty->buf[vty->cp - 1];

		vty_backward_char(vty);
		vty_self_insert_overwrite(vty, c1);
		vty_self_insert_overwrite(vty, c2);
	}
}

/* Do completion at vty interface. */
static void vty_complete_command(struct vty *vty)
{
	int i;
	int ret;
	char **matched = NULL;
	vector vline;

	if (vty->node == AUTH_NODE || vty->node == AUTH_ENABLE_NODE)
		return;

	vline = cmd_make_strvec(vty->buf);
	if (vline == NULL)
		return;

	/* In case of 'help \t'. */
	if (isspace((unsigned char)vty->buf[vty->length - 1]))
		vector_set(vline, NULL);

	matched = cmd_complete_command(vline, vty, &ret);

	cmd_free_strvec(vline);

	vty_out(vty, "\n");
	switch (ret) {
	case CMD_ERR_AMBIGUOUS:
		vty_out(vty, "%% Ambiguous command.\n");
		vty_prompt(vty);
		vty_redraw_line(vty);
		break;
	case CMD_ERR_NO_MATCH:
		/* vty_out (vty, "%% There is no matched command.\n"); */
		vty_prompt(vty);
		vty_redraw_line(vty);
		break;
	case CMD_COMPLETE_FULL_MATCH:
		if (!matched[0]) {
			/* 2016-11-28 equinox -- need to debug, SEGV here */
			vty_out(vty, "%% CLI BUG: FULL_MATCH with NULL str\n");
			vty_prompt(vty);
			vty_redraw_line(vty);
			break;
		}
		vty_prompt(vty);
		vty_redraw_line(vty);
		vty_backward_pure_word(vty);
		vty_insert_word_overwrite(vty, matched[0]);
		vty_self_insert(vty, ' ');
		XFREE(MTYPE_COMPLETION, matched[0]);
		break;
	case CMD_COMPLETE_MATCH:
		vty_prompt(vty);
		vty_redraw_line(vty);
		vty_backward_pure_word(vty);
		vty_insert_word_overwrite(vty, matched[0]);
		XFREE(MTYPE_COMPLETION, matched[0]);
		break;
	case CMD_COMPLETE_LIST_MATCH:
		for (i = 0; matched[i] != NULL; i++) {
			if (i != 0 && ((i % 6) == 0))
				vty_out(vty, "\n");
			vty_out(vty, "%-10s ", matched[i]);
			XFREE(MTYPE_COMPLETION, matched[i]);
		}
		vty_out(vty, "\n");

		vty_prompt(vty);
		vty_redraw_line(vty);
		break;
	case CMD_ERR_NOTHING_TODO:
		vty_prompt(vty);
		vty_redraw_line(vty);
		break;
	default:
		break;
	}
	XFREE(MTYPE_TMP, matched);
}

static void vty_describe_fold(struct vty *vty, int cmd_width,
			      unsigned int desc_width, struct cmd_token *token)
{
	char *buf;
	const char *cmd, *p;
	int pos;

	cmd = token->text;

	if (desc_width <= 0) {
		vty_out(vty, "  %-*s  %s\n", cmd_width, cmd, token->desc);
		return;
	}

	buf = XCALLOC(MTYPE_TMP, strlen(token->desc) + 1);

	for (p = token->desc; strlen(p) > desc_width; p += pos + 1) {
		for (pos = desc_width; pos > 0; pos--)
			if (*(p + pos) == ' ')
				break;

		if (pos == 0)
			break;

		memcpy(buf, p, pos);
		buf[pos] = '\0';
		vty_out(vty, "  %-*s  %s\n", cmd_width, cmd, buf);

		cmd = "";
	}

	vty_out(vty, "  %-*s  %s\n", cmd_width, cmd, p);

	XFREE(MTYPE_TMP, buf);
}

/* Describe matched command function. */
static void vty_describe_command(struct vty *vty)
{
	int ret;
	vector vline;
	vector describe;
	unsigned int i, width, desc_width;
	struct cmd_token *token, *token_cr = NULL;

	vline = cmd_make_strvec(vty->buf);

	/* In case of '> ?'. */
	if (vline == NULL) {
		vline = vector_init(1);
		vector_set(vline, NULL);
	} else if (isspace((unsigned char)vty->buf[vty->length - 1]))
		vector_set(vline, NULL);

	describe = cmd_describe_command(vline, vty, &ret);

	vty_out(vty, "\n");

	/* Ambiguous error. */
	switch (ret) {
	case CMD_ERR_AMBIGUOUS:
		vty_out(vty, "%% Ambiguous command.\n");
		goto out;
		break;
	case CMD_ERR_NO_MATCH:
		vty_out(vty, "%% There is no matched command.\n");
		goto out;
		break;
	}

	/* Get width of command string. */
	width = 0;
	for (i = 0; i < vector_active(describe); i++)
		if ((token = vector_slot(describe, i)) != NULL) {
			unsigned int len;

			if (token->text[0] == '\0')
				continue;

			len = strlen(token->text);

			if (width < len)
				width = len;
		}

	/* Get width of description string. */
	desc_width = vty->width - (width + 6);

	/* Print out description. */
	for (i = 0; i < vector_active(describe); i++)
		if ((token = vector_slot(describe, i)) != NULL) {
			if (token->text[0] == '\0')
				continue;

			if (strcmp(token->text, CMD_CR_TEXT) == 0) {
				token_cr = token;
				continue;
			}

			if (!token->desc)
				vty_out(vty, "  %-s\n", token->text);
			else if (desc_width >= strlen(token->desc))
				vty_out(vty, "  %-*s  %s\n", width, token->text,
					token->desc);
			else
				vty_describe_fold(vty, width, desc_width,
						  token);

			if (IS_VARYING_TOKEN(token->type)) {
				const char *ref = vector_slot(
					vline, vector_active(vline) - 1);

				vector varcomps = vector_init(VECTOR_MIN_SIZE);
				cmd_variable_complete(token, ref, varcomps);

				if (vector_active(varcomps) > 0) {
					char *ac = cmd_variable_comp2str(
						varcomps, vty->width);
					vty_out(vty, "%s\n", ac);
					XFREE(MTYPE_TMP, ac);
				}

				vector_free(varcomps);
			}
#if 0
        vty_out (vty, "  %-*s %s\n", width
                 desc->cmd[0] == '.' ? desc->cmd + 1 : desc->cmd,
                 desc->str ? desc->str : "");
#endif /* 0 */
		}

	if ((token = token_cr)) {
		if (!token->desc)
			vty_out(vty, "  %-s\n", token->text);
		else if (desc_width >= strlen(token->desc))
			vty_out(vty, "  %-*s  %s\n", width, token->text,
				token->desc);
		else
			vty_describe_fold(vty, width, desc_width, token);
	}

out:
	cmd_free_strvec(vline);
	if (describe)
		vector_free(describe);

	vty_prompt(vty);
	vty_redraw_line(vty);
}

static void vty_clear_buf(struct vty *vty)
{
	memset(vty->buf, 0, vty->max);
}

/* ^C stop current input and do not add command line to the history. */
static void vty_stop_input(struct vty *vty)
{
	vty->cp = vty->length = 0;
	vty_clear_buf(vty);
	vty_out(vty, "\n");

	if (vty->config) {
		vty_config_exit(vty);
		vty->node = ENABLE_NODE;
	}

	vty_prompt(vty);

	/* Set history pointer to the latest one. */
	vty->hp = vty->hindex;
}

/* Add current command line to the history buffer. */
static void vty_hist_add(struct vty *vty)
{
	int index;

	if (vty->length == 0)
		return;

	index = vty->hindex ? vty->hindex - 1 : VTY_MAXHIST - 1;

	/* Ignore the same string as previous one. */
	if (vty->hist[index])
		if (strcmp(vty->buf, vty->hist[index]) == 0) {
			vty->hp = vty->hindex;
			return;
		}

	/* Insert history entry. */
	XFREE(MTYPE_VTY_HIST, vty->hist[vty->hindex]);
	vty->hist[vty->hindex] = XSTRDUP(MTYPE_VTY_HIST, vty->buf);

	/* History index rotation. */
	vty->hindex++;
	if (vty->hindex == VTY_MAXHIST)
		vty->hindex = 0;

	vty->hp = vty->hindex;
}

/* #define TELNET_OPTION_DEBUG */

/* Get telnet window size. */
static int vty_telnet_option(struct vty *vty, unsigned char *buf, int nbytes)
{
#ifdef TELNET_OPTION_DEBUG
	int i;

	for (i = 0; i < nbytes; i++) {
		switch (buf[i]) {
		case IAC:
			vty_out(vty, "IAC ");
			break;
		case WILL:
			vty_out(vty, "WILL ");
			break;
		case WONT:
			vty_out(vty, "WONT ");
			break;
		case DO:
			vty_out(vty, "DO ");
			break;
		case DONT:
			vty_out(vty, "DONT ");
			break;
		case SB:
			vty_out(vty, "SB ");
			break;
		case SE:
			vty_out(vty, "SE ");
			break;
		case TELOPT_ECHO:
			vty_out(vty, "TELOPT_ECHO \n");
			break;
		case TELOPT_SGA:
			vty_out(vty, "TELOPT_SGA \n");
			break;
		case TELOPT_NAWS:
			vty_out(vty, "TELOPT_NAWS \n");
			break;
		default:
			vty_out(vty, "%x ", buf[i]);
			break;
		}
	}
	vty_out(vty, "\n");

#endif /* TELNET_OPTION_DEBUG */

	switch (buf[0]) {
	case SB:
		vty->sb_len = 0;
		vty->iac_sb_in_progress = 1;
		return 0;
	case SE: {
		if (!vty->iac_sb_in_progress)
			return 0;

		if ((vty->sb_len == 0) || (vty->sb_buf[0] == '\0')) {
			vty->iac_sb_in_progress = 0;
			return 0;
		}
		switch (vty->sb_buf[0]) {
		case TELOPT_NAWS:
			if (vty->sb_len != TELNET_NAWS_SB_LEN)
				flog_err(
					EC_LIB_SYSTEM_CALL,
					"RFC 1073 violation detected: telnet NAWS option "
					"should send %d characters, but we received %lu",
					TELNET_NAWS_SB_LEN,
					(unsigned long)vty->sb_len);
			else if (sizeof(vty->sb_buf) < TELNET_NAWS_SB_LEN)
				flog_err(
					EC_LIB_DEVELOPMENT,
					"Bug detected: sizeof(vty->sb_buf) %lu < %d, too small to handle the telnet NAWS option",
					(unsigned long)sizeof(vty->sb_buf),
					TELNET_NAWS_SB_LEN);
			else {
				vty->width = ((vty->sb_buf[1] << 8)
					      | vty->sb_buf[2]);
				vty->height = ((vty->sb_buf[3] << 8)
					       | vty->sb_buf[4]);
#ifdef TELNET_OPTION_DEBUG
				vty_out(vty,
					"TELNET NAWS window size negotiation completed: "
					"width %d, height %d\n",
					vty->width, vty->height);
#endif
			}
			break;
		}
		vty->iac_sb_in_progress = 0;
		return 0;
	}
	default:
		break;
	}
	return 1;
}

/* Execute current command line. */
static int vty_execute(struct vty *vty)
{
	int ret;

	ret = CMD_SUCCESS;

	switch (vty->node) {
	case AUTH_NODE:
	case AUTH_ENABLE_NODE:
		vty_auth(vty, vty->buf);
		break;
	default:
		ret = vty_command(vty, vty->buf);
		if (vty->type == VTY_TERM)
			vty_hist_add(vty);
		break;
	}

	/* Clear command line buffer. */
	vty->cp = vty->length = 0;
	vty_clear_buf(vty);

	if (vty->status != VTY_CLOSE)
		vty_prompt(vty);

	return ret;
}

#define CONTROL(X)  ((X) - '@')
#define VTY_NORMAL     0
#define VTY_PRE_ESCAPE 1
#define VTY_ESCAPE     2

/* Escape character command map. */
static void vty_escape_map(unsigned char c, struct vty *vty)
{
	switch (c) {
	case ('A'):
		vty_previous_line(vty);
		break;
	case ('B'):
		vty_next_line(vty);
		break;
	case ('C'):
		vty_forward_char(vty);
		break;
	case ('D'):
		vty_backward_char(vty);
		break;
	default:
		break;
	}

	/* Go back to normal mode. */
	vty->escape = VTY_NORMAL;
}

/* Quit print out to the buffer. */
static void vty_buffer_reset(struct vty *vty)
{
	buffer_reset(vty->obuf);
	buffer_reset(vty->lbuf);
	vty_prompt(vty);
	vty_redraw_line(vty);
}

/* Read data via vty socket. */
static int vty_read(struct thread *thread)
{
	int i;
	int nbytes;
	unsigned char buf[VTY_READ_BUFSIZ];

	int vty_sock = THREAD_FD(thread);
	struct vty *vty = THREAD_ARG(thread);

	/* Read raw data from socket */
	if ((nbytes = read(vty->fd, buf, VTY_READ_BUFSIZ)) <= 0) {
		if (nbytes < 0) {
			if (ERRNO_IO_RETRY(errno)) {
				vty_event(VTY_READ, vty_sock, vty);
				return 0;
			}
			vty->monitor = 0; /* disable monitoring to avoid
					     infinite recursion */
			flog_err(
				EC_LIB_SOCKET,
				"%s: read error on vty client fd %d, closing: %s",
				__func__, vty->fd, safe_strerror(errno));
			buffer_reset(vty->obuf);
			buffer_reset(vty->lbuf);
		}
		vty->status = VTY_CLOSE;
	}

	for (i = 0; i < nbytes; i++) {
		if (buf[i] == IAC) {
			if (!vty->iac) {
				vty->iac = 1;
				continue;
			} else {
				vty->iac = 0;
			}
		}

		if (vty->iac_sb_in_progress && !vty->iac) {
			if (vty->sb_len < sizeof(vty->sb_buf))
				vty->sb_buf[vty->sb_len] = buf[i];
			vty->sb_len++;
			continue;
		}

		if (vty->iac) {
			/* In case of telnet command */
			int ret = 0;
			ret = vty_telnet_option(vty, buf + i, nbytes - i);
			vty->iac = 0;
			i += ret;
			continue;
		}


		if (vty->status == VTY_MORE) {
			switch (buf[i]) {
			case CONTROL('C'):
			case 'q':
			case 'Q':
				vty_buffer_reset(vty);
				break;
#if 0 /* More line does not work for "show ip bgp".  */
            case '\n':
            case '\r':
              vty->status = VTY_MORELINE;
              break;
#endif
			default:
				break;
			}
			continue;
		}

		/* Escape character. */
		if (vty->escape == VTY_ESCAPE) {
			vty_escape_map(buf[i], vty);
			continue;
		}

		/* Pre-escape status. */
		if (vty->escape == VTY_PRE_ESCAPE) {
			switch (buf[i]) {
			case '[':
				vty->escape = VTY_ESCAPE;
				break;
			case 'b':
				vty_backward_word(vty);
				vty->escape = VTY_NORMAL;
				break;
			case 'f':
				vty_forward_word(vty);
				vty->escape = VTY_NORMAL;
				break;
			case 'd':
				vty_forward_kill_word(vty);
				vty->escape = VTY_NORMAL;
				break;
			case CONTROL('H'):
			case 0x7f:
				vty_backward_kill_word(vty);
				vty->escape = VTY_NORMAL;
				break;
			default:
				vty->escape = VTY_NORMAL;
				break;
			}
			continue;
		}

		switch (buf[i]) {
		case CONTROL('A'):
			vty_beginning_of_line(vty);
			break;
		case CONTROL('B'):
			vty_backward_char(vty);
			break;
		case CONTROL('C'):
			vty_stop_input(vty);
			break;
		case CONTROL('D'):
			vty_delete_char(vty);
			break;
		case CONTROL('E'):
			vty_end_of_line(vty);
			break;
		case CONTROL('F'):
			vty_forward_char(vty);
			break;
		case CONTROL('H'):
		case 0x7f:
			vty_delete_backward_char(vty);
			break;
		case CONTROL('K'):
			vty_kill_line(vty);
			break;
		case CONTROL('N'):
			vty_next_line(vty);
			break;
		case CONTROL('P'):
			vty_previous_line(vty);
			break;
		case CONTROL('T'):
			vty_transpose_chars(vty);
			break;
		case CONTROL('U'):
			vty_kill_line_from_beginning(vty);
			break;
		case CONTROL('W'):
			vty_backward_kill_word(vty);
			break;
		case CONTROL('Z'):
			vty_end_config(vty);
			break;
		case '\n':
		case '\r':
			vty_out(vty, "\n");
			vty_execute(vty);
			break;
		case '\t':
			vty_complete_command(vty);
			break;
		case '?':
			if (vty->node == AUTH_NODE
			    || vty->node == AUTH_ENABLE_NODE)
				vty_self_insert(vty, buf[i]);
			else
				vty_describe_command(vty);
			break;
		case '\033':
			if (i + 1 < nbytes && buf[i + 1] == '[') {
				vty->escape = VTY_ESCAPE;
				i++;
			} else
				vty->escape = VTY_PRE_ESCAPE;
			break;
		default:
			if (buf[i] > 31 && buf[i] < 127)
				vty_self_insert(vty, buf[i]);
			break;
		}
	}

	/* Check status. */
	if (vty->status == VTY_CLOSE)
		vty_close(vty);
	else {
		vty_event(VTY_WRITE, vty->wfd, vty);
		vty_event(VTY_READ, vty_sock, vty);
	}
	return 0;
}

/* Flush buffer to the vty. */
static int vty_flush(struct thread *thread)
{
	int erase;
	buffer_status_t flushrc;
	int vty_sock = THREAD_FD(thread);
	struct vty *vty = THREAD_ARG(thread);

	/* Tempolary disable read thread. */
	if (vty->lines == 0)
		THREAD_OFF(vty->t_read);

	/* Function execution continue. */
	erase = ((vty->status == VTY_MORE || vty->status == VTY_MORELINE));

	/* N.B. if width is 0, that means we don't know the window size. */
	if ((vty->lines == 0) || (vty->width == 0) || (vty->height == 0))
		flushrc = buffer_flush_available(vty->obuf, vty_sock);
	else if (vty->status == VTY_MORELINE)
		flushrc = buffer_flush_window(vty->obuf, vty_sock, vty->width,
					      1, erase, 0);
	else
		flushrc = buffer_flush_window(
			vty->obuf, vty_sock, vty->width,
			vty->lines >= 0 ? vty->lines : vty->height, erase, 0);
	switch (flushrc) {
	case BUFFER_ERROR:
		vty->monitor =
			0; /* disable monitoring to avoid infinite recursion */
		zlog_info("buffer_flush failed on vty client fd %d, closing",
			  vty->fd);
		buffer_reset(vty->lbuf);
		buffer_reset(vty->obuf);
		vty_close(vty);
		return 0;
	case BUFFER_EMPTY:
		if (vty->status == VTY_CLOSE)
			vty_close(vty);
		else {
			vty->status = VTY_NORMAL;
			if (vty->lines == 0)
				vty_event(VTY_READ, vty_sock, vty);
		}
		break;
	case BUFFER_PENDING:
		/* There is more data waiting to be written. */
		vty->status = VTY_MORE;
		if (vty->lines == 0)
			vty_event(VTY_WRITE, vty_sock, vty);
		break;
	}

	return 0;
}

/* Allocate new vty struct. */
struct vty *vty_new(void)
{
	struct vty *new = XCALLOC(MTYPE_VTY, sizeof(struct vty));

	new->fd = new->wfd = -1;
	new->of = stdout;
	new->lbuf = buffer_new(0);
	new->obuf = buffer_new(0); /* Use default buffer size. */
	new->buf = XCALLOC(MTYPE_VTY, VTY_BUFSIZ);
	new->max = VTY_BUFSIZ;

	return new;
}


/* allocate and initialise vty */
static struct vty *vty_new_init(int vty_sock)
{
	struct vty *vty;

	vty = vty_new();
	vty->fd = vty_sock;
	vty->wfd = vty_sock;
	vty->type = VTY_TERM;
	vty->node = AUTH_NODE;
	vty->fail = 0;
	vty->cp = 0;
	vty_clear_buf(vty);
	vty->length = 0;
	memset(vty->hist, 0, sizeof(vty->hist));
	vty->hp = 0;
	vty->hindex = 0;
	vty->xpath_index = 0;
	memset(vty->xpath, 0, sizeof(vty->xpath));
	vty->private_config = false;
	vty->candidate_config = vty_shared_candidate_config;
	vector_set_index(vtyvec, vty_sock, vty);
	vty->status = VTY_NORMAL;
	vty->lines = -1;
	vty->iac = 0;
	vty->iac_sb_in_progress = 0;
	vty->sb_len = 0;

	return vty;
}

/* Create new vty structure. */
static struct vty *vty_create(int vty_sock, union sockunion *su)
{
	char buf[SU_ADDRSTRLEN];
	struct vty *vty;

	sockunion2str(su, buf, SU_ADDRSTRLEN);

	/* Allocate new vty structure and set up default values. */
	vty = vty_new_init(vty_sock);

	/* configurable parameters not part of basic init */
	vty->v_timeout = vty_timeout_val;
	strlcpy(vty->address, buf, sizeof(vty->address));
	if (no_password_check) {
		if (host.advanced)
			vty->node = ENABLE_NODE;
		else
			vty->node = VIEW_NODE;
	}
	if (host.lines >= 0)
		vty->lines = host.lines;

	if (!no_password_check) {
		/* Vty is not available if password isn't set. */
		if (host.password == NULL && host.password_encrypt == NULL) {
			vty_out(vty, "Vty password is not set.\n");
			vty->status = VTY_CLOSE;
			vty_close(vty);
			return NULL;
		}
	}

	/* Say hello to the world. */
	vty_hello(vty);
	if (!no_password_check)
		vty_out(vty, "\nUser Access Verification\n\n");

	/* Setting up terminal. */
	vty_will_echo(vty);
	vty_will_suppress_go_ahead(vty);

	vty_dont_linemode(vty);
	vty_do_window_size(vty);
	/* vty_dont_lflow_ahead (vty); */

	vty_prompt(vty);

	/* Add read/write thread. */
	vty_event(VTY_WRITE, vty_sock, vty);
	vty_event(VTY_READ, vty_sock, vty);

	return vty;
}

/* create vty for stdio */
static struct termios stdio_orig_termios;
static struct vty *stdio_vty = NULL;
static bool stdio_termios = false;
static void (*stdio_vty_atclose)(int isexit);

static void vty_stdio_reset(int isexit)
{
	if (stdio_vty) {
		if (stdio_termios)
			tcsetattr(0, TCSANOW, &stdio_orig_termios);
		stdio_termios = false;

		stdio_vty = NULL;

		if (stdio_vty_atclose)
			stdio_vty_atclose(isexit);
		stdio_vty_atclose = NULL;
	}
}

static void vty_stdio_atexit(void)
{
	vty_stdio_reset(1);
}

void vty_stdio_suspend(void)
{
	if (!stdio_vty)
		return;

	THREAD_OFF(stdio_vty->t_write);
	THREAD_OFF(stdio_vty->t_read);
	THREAD_OFF(stdio_vty->t_timeout);

	if (stdio_termios)
		tcsetattr(0, TCSANOW, &stdio_orig_termios);
	stdio_termios = false;
}

void vty_stdio_resume(void)
{
	if (!stdio_vty)
		return;

	if (!tcgetattr(0, &stdio_orig_termios)) {
		struct termios termios;

		termios = stdio_orig_termios;
		termios.c_iflag &= ~(IGNBRK | BRKINT | PARMRK | ISTRIP | INLCR
				     | IGNCR | ICRNL | IXON);
		termios.c_oflag &= ~OPOST;
		termios.c_lflag &= ~(ECHO | ECHONL | ICANON | IEXTEN);
		termios.c_cflag &= ~(CSIZE | PARENB);
		termios.c_cflag |= CS8;
		tcsetattr(0, TCSANOW, &termios);
		stdio_termios = true;
	}

	vty_prompt(stdio_vty);

	/* Add read/write thread. */
	vty_event(VTY_WRITE, 1, stdio_vty);
	vty_event(VTY_READ, 0, stdio_vty);
}

void vty_stdio_close(void)
{
	if (!stdio_vty)
		return;
	vty_close(stdio_vty);
}

struct vty *vty_stdio(void (*atclose)(int isexit))
{
	struct vty *vty;

	/* refuse creating two vtys on stdio */
	if (stdio_vty)
		return NULL;

	vty = stdio_vty = vty_new_init(0);
	stdio_vty_atclose = atclose;
	vty->wfd = 1;

	/* always have stdio vty in a known _unchangeable_ state, don't want
	 * config
	 * to have any effect here to make sure scripting this works as intended
	 */
	vty->node = ENABLE_NODE;
	vty->v_timeout = 0;
	strlcpy(vty->address, "console", sizeof(vty->address));

	vty_stdio_resume();
	return vty;
}

/* Accept connection from the network. */
static int vty_accept(struct thread *thread)
{
	int vty_sock;
	union sockunion su;
	int ret;
	unsigned int on;
	int accept_sock;
	struct prefix p;
	struct access_list *acl = NULL;
	char buf[SU_ADDRSTRLEN];

	accept_sock = THREAD_FD(thread);

	/* We continue hearing vty socket. */
	vty_event(VTY_SERV, accept_sock, NULL);

	memset(&su, 0, sizeof(union sockunion));

	/* We can handle IPv4 or IPv6 socket. */
	vty_sock = sockunion_accept(accept_sock, &su);
	if (vty_sock < 0) {
		flog_err(EC_LIB_SOCKET, "can't accept vty socket : %s",
			 safe_strerror(errno));
		return -1;
	}
	set_nonblocking(vty_sock);
	set_cloexec(vty_sock);

	sockunion2hostprefix(&su, &p);

	/* VTY's accesslist apply. */
	if (p.family == AF_INET && vty_accesslist_name) {
		if ((acl = access_list_lookup(AFI_IP, vty_accesslist_name))
		    && (access_list_apply(acl, &p) == FILTER_DENY)) {
			zlog_info("Vty connection refused from %s",
				  sockunion2str(&su, buf, SU_ADDRSTRLEN));
			close(vty_sock);

			/* continue accepting connections */
			vty_event(VTY_SERV, accept_sock, NULL);

			return 0;
		}
	}

	/* VTY's ipv6 accesslist apply. */
	if (p.family == AF_INET6 && vty_ipv6_accesslist_name) {
		if ((acl = access_list_lookup(AFI_IP6,
					      vty_ipv6_accesslist_name))
		    && (access_list_apply(acl, &p) == FILTER_DENY)) {
			zlog_info("Vty connection refused from %s",
				  sockunion2str(&su, buf, SU_ADDRSTRLEN));
			close(vty_sock);

			/* continue accepting connections */
			vty_event(VTY_SERV, accept_sock, NULL);

			return 0;
		}
	}

	on = 1;
	ret = setsockopt(vty_sock, IPPROTO_TCP, TCP_NODELAY, (char *)&on,
			 sizeof(on));
	if (ret < 0)
		zlog_info("can't set sockopt to vty_sock : %s",
			  safe_strerror(errno));

	zlog_info("Vty connection from %s",
		  sockunion2str(&su, buf, SU_ADDRSTRLEN));

	vty_create(vty_sock, &su);

	return 0;
}

static void vty_serv_sock_addrinfo(const char *hostname, unsigned short port)
{
	int ret;
	struct addrinfo req;
	struct addrinfo *ainfo;
	struct addrinfo *ainfo_save;
	int sock;
	char port_str[BUFSIZ];

	memset(&req, 0, sizeof(struct addrinfo));
	req.ai_flags = AI_PASSIVE;
	req.ai_family = AF_UNSPEC;
	req.ai_socktype = SOCK_STREAM;
	sprintf(port_str, "%d", port);
	port_str[sizeof(port_str) - 1] = '\0';

	ret = getaddrinfo(hostname, port_str, &req, &ainfo);

	if (ret != 0) {
		flog_err_sys(EC_LIB_SYSTEM_CALL, "getaddrinfo failed: %s",
			     gai_strerror(ret));
		exit(1);
	}

	ainfo_save = ainfo;

	do {
		if (ainfo->ai_family != AF_INET && ainfo->ai_family != AF_INET6)
			continue;

		sock = socket(ainfo->ai_family, ainfo->ai_socktype,
			      ainfo->ai_protocol);
		if (sock < 0)
			continue;

		sockopt_v6only(ainfo->ai_family, sock);
		sockopt_reuseaddr(sock);
		sockopt_reuseport(sock);
		set_cloexec(sock);

		ret = bind(sock, ainfo->ai_addr, ainfo->ai_addrlen);
		if (ret < 0) {
			close(sock); /* Avoid sd leak. */
			continue;
		}

		ret = listen(sock, 3);
		if (ret < 0) {
			close(sock); /* Avoid sd leak. */
			continue;
		}

		vty_event(VTY_SERV, sock, NULL);
	} while ((ainfo = ainfo->ai_next) != NULL);

	freeaddrinfo(ainfo_save);
}

#ifdef VTYSH
/* For sockaddr_un. */
#include <sys/un.h>

/* VTY shell UNIX domain socket. */
static void vty_serv_un(const char *path)
{
	int ret;
	int sock, len;
	struct sockaddr_un serv;
	mode_t old_mask;
	struct zprivs_ids_t ids;

	/* First of all, unlink existing socket */
	unlink(path);

	/* Set umask */
	old_mask = umask(0007);

	/* Make UNIX domain socket. */
	sock = socket(AF_UNIX, SOCK_STREAM, 0);
	if (sock < 0) {
		flog_err_sys(EC_LIB_SOCKET,
			     "Cannot create unix stream socket: %s",
			     safe_strerror(errno));
		return;
	}

	/* Make server socket. */
	memset(&serv, 0, sizeof(struct sockaddr_un));
	serv.sun_family = AF_UNIX;
	strlcpy(serv.sun_path, path, sizeof(serv.sun_path));
#ifdef HAVE_STRUCT_SOCKADDR_UN_SUN_LEN
	len = serv.sun_len = SUN_LEN(&serv);
#else
	len = sizeof(serv.sun_family) + strlen(serv.sun_path);
#endif /* HAVE_STRUCT_SOCKADDR_UN_SUN_LEN */

	set_cloexec(sock);

	ret = bind(sock, (struct sockaddr *)&serv, len);
	if (ret < 0) {
		flog_err_sys(EC_LIB_SOCKET, "Cannot bind path %s: %s", path,
			     safe_strerror(errno));
		close(sock); /* Avoid sd leak. */
		return;
	}

	ret = listen(sock, 5);
	if (ret < 0) {
		flog_err_sys(EC_LIB_SOCKET, "listen(fd %d) failed: %s", sock,
			     safe_strerror(errno));
		close(sock); /* Avoid sd leak. */
		return;
	}

	umask(old_mask);

	zprivs_get_ids(&ids);

	/* Hack: ids.gid_vty is actually a uint, but we stored -1 in it
	   earlier for the case when we don't need to chown the file
	   type casting it here to make a compare */
	if ((int)ids.gid_vty > 0) {
		/* set group of socket */
		if (chown(path, -1, ids.gid_vty)) {
			flog_err_sys(EC_LIB_SYSTEM_CALL,
				     "vty_serv_un: could chown socket, %s",
				     safe_strerror(errno));
		}
	}

	vty_event(VTYSH_SERV, sock, NULL);
}

/* #define VTYSH_DEBUG 1 */

static int vtysh_accept(struct thread *thread)
{
	int accept_sock;
	int sock;
	int client_len;
	struct sockaddr_un client;
	struct vty *vty;

	accept_sock = THREAD_FD(thread);

	vty_event(VTYSH_SERV, accept_sock, NULL);

	memset(&client, 0, sizeof(struct sockaddr_un));
	client_len = sizeof(struct sockaddr_un);

	sock = accept(accept_sock, (struct sockaddr *)&client,
		      (socklen_t *)&client_len);

	if (sock < 0) {
		flog_err(EC_LIB_SOCKET, "can't accept vty socket : %s",
			 safe_strerror(errno));
		return -1;
	}

	if (set_nonblocking(sock) < 0) {
		flog_err(
			EC_LIB_SOCKET,
			"vtysh_accept: could not set vty socket %d to non-blocking, %s, closing",
			sock, safe_strerror(errno));
		close(sock);
		return -1;
	}
	set_cloexec(sock);

#ifdef VTYSH_DEBUG
	printf("VTY shell accept\n");
#endif /* VTYSH_DEBUG */

	vty = vty_new();
	vty->fd = sock;
	vty->wfd = sock;
	vty->type = VTY_SHELL_SERV;
	vty->node = VIEW_NODE;

	vty_event(VTYSH_READ, sock, vty);

	return 0;
}

static int vtysh_flush(struct vty *vty)
{
	switch (buffer_flush_available(vty->obuf, vty->wfd)) {
	case BUFFER_PENDING:
		vty_event(VTYSH_WRITE, vty->wfd, vty);
		break;
	case BUFFER_ERROR:
		vty->monitor =
			0; /* disable monitoring to avoid infinite recursion */
		flog_err(EC_LIB_SOCKET, "%s: write error to fd %d, closing",
			 __func__, vty->fd);
		buffer_reset(vty->lbuf);
		buffer_reset(vty->obuf);
		vty_close(vty);
		return -1;
	case BUFFER_EMPTY:
		break;
	}
	return 0;
}

static int vtysh_read(struct thread *thread)
{
	int ret;
	int sock;
	int nbytes;
	struct vty *vty;
	unsigned char buf[VTY_READ_BUFSIZ];
	unsigned char *p;
	uint8_t header[4] = {0, 0, 0, 0};

	sock = THREAD_FD(thread);
	vty = THREAD_ARG(thread);

	if ((nbytes = read(sock, buf, VTY_READ_BUFSIZ)) <= 0) {
		if (nbytes < 0) {
			if (ERRNO_IO_RETRY(errno)) {
				vty_event(VTYSH_READ, sock, vty);
				return 0;
			}
			vty->monitor = 0; /* disable monitoring to avoid
					     infinite recursion */
			flog_err(
				EC_LIB_SOCKET,
				"%s: read failed on vtysh client fd %d, closing: %s",
				__func__, sock, safe_strerror(errno));
		}
		buffer_reset(vty->lbuf);
		buffer_reset(vty->obuf);
		vty_close(vty);
#ifdef VTYSH_DEBUG
		printf("close vtysh\n");
#endif /* VTYSH_DEBUG */
		return 0;
	}

#ifdef VTYSH_DEBUG
	printf("line: %.*s\n", nbytes, buf);
#endif /* VTYSH_DEBUG */

	if (vty->length + nbytes >= VTY_BUFSIZ) {
		/* Clear command line buffer. */
		vty->cp = vty->length = 0;
		vty_clear_buf(vty);
		vty_out(vty, "%% Command is too long.\n");
	} else {
		for (p = buf; p < buf + nbytes; p++) {
			vty->buf[vty->length++] = *p;
			if (*p == '\0') {
				/* Pass this line to parser. */
				ret = vty_execute(vty);
/* Note that vty_execute clears the command buffer and resets
   vty->length to 0. */

/* Return result. */
#ifdef VTYSH_DEBUG
				printf("result: %d\n", ret);
				printf("vtysh node: %d\n", vty->node);
#endif /* VTYSH_DEBUG */

				/* hack for asynchronous "write integrated"
				 * - other commands in "buf" will be ditched
				 * - input during pending config-write is
				 * "unsupported" */
				if (ret == CMD_SUSPEND)
					break;

				/* warning: watchfrr hardcodes this result write
				 */
				header[3] = ret;
				buffer_put(vty->obuf, header, 4);

				if (!vty->t_write && (vtysh_flush(vty) < 0))
					/* Try to flush results; exit if a write
					 * error occurs. */
					return 0;
			}
		}
	}

	if (vty->status == VTY_CLOSE)
		vty_close(vty);
	else
		vty_event(VTYSH_READ, sock, vty);

	return 0;
}

static int vtysh_write(struct thread *thread)
{
	struct vty *vty = THREAD_ARG(thread);

	vtysh_flush(vty);
	return 0;
}

#endif /* VTYSH */

/* Determine address family to bind. */
void vty_serv_sock(const char *addr, unsigned short port, const char *path)
{
	/* If port is set to 0, do not listen on TCP/IP at all! */
	if (port)
		vty_serv_sock_addrinfo(addr, port);

#ifdef VTYSH
	vty_serv_un(path);
#endif /* VTYSH */
}

static void vty_error_delete(void *arg)
{
	struct vty_error *ve = arg;

	XFREE(MTYPE_TMP, ve);
}

/* Close vty interface.  Warning: call this only from functions that
   will be careful not to access the vty afterwards (since it has
   now been freed).  This is safest from top-level functions (called
   directly by the thread dispatcher). */
void vty_close(struct vty *vty)
{
	int i;
	bool was_stdio = false;

	/* Cancel threads.*/
	THREAD_OFF(vty->t_read);
	THREAD_OFF(vty->t_write);
	THREAD_OFF(vty->t_timeout);

	/* Flush buffer. */
	buffer_flush_all(vty->obuf, vty->wfd);

	/* Free input buffer. */
	buffer_free(vty->obuf);
	buffer_free(vty->lbuf);

	/* Free command history. */
	for (i = 0; i < VTY_MAXHIST; i++) {
		XFREE(MTYPE_VTY_HIST, vty->hist[i]);
	}

	/* Unset vector. */
	if (vty->fd != -1)
		vector_unset(vtyvec, vty->fd);

	if (vty->wfd > 0 && vty->type == VTY_FILE)
		fsync(vty->wfd);

	/* Close socket.
	 * note check is for fd > STDERR_FILENO, not fd != -1.
	 * We never close stdin/stdout/stderr here, because we may be
	 * running in foreground mode with logging to stdout.  Also,
	 * additionally, we'd need to replace these fds with /dev/null. */
	if (vty->wfd > STDERR_FILENO && vty->wfd != vty->fd)
		close(vty->wfd);
	if (vty->fd > STDERR_FILENO)
		close(vty->fd);
	if (vty->fd == STDIN_FILENO)
		was_stdio = true;

	XFREE(MTYPE_VTY, vty->buf);

	if (vty->error) {
		vty->error->del = vty_error_delete;
		list_delete(&vty->error);
	}

	/* Check configure. */
	vty_config_exit(vty);

	/* OK free vty. */
	XFREE(MTYPE_VTY, vty);

	if (was_stdio)
		vty_stdio_reset(0);
}

/* When time out occur output message then close connection. */
static int vty_timeout(struct thread *thread)
{
	struct vty *vty;

	vty = THREAD_ARG(thread);
	vty->v_timeout = 0;

	/* Clear buffer*/
	buffer_reset(vty->lbuf);
	buffer_reset(vty->obuf);
	vty_out(vty, "\nVty connection is timed out.\n");

	/* Close connection. */
	vty->status = VTY_CLOSE;
	vty_close(vty);

	return 0;
}

/* Read up configuration file from file_name. */
static void vty_read_file(struct nb_config *config, FILE *confp)
{
	int ret;
	struct vty *vty;
	struct vty_error *ve;
	struct listnode *node;
	unsigned int line_num = 0;

	vty = vty_new();
	/* vty_close won't close stderr;  if some config command prints
	 * something it'll end up there.  (not ideal; it'd be beter if output
	 * from a file-load went to logging instead.  Also note that if this
	 * function is called after daemonizing, stderr will be /dev/null.)
	 *
	 * vty->fd will be -1 from vty_new()
	 */
	vty->wfd = STDERR_FILENO;
	vty->type = VTY_FILE;
	vty->node = CONFIG_NODE;
	vty->config = true;
	if (config)
		vty->candidate_config = config;
	else {
		vty->private_config = true;
		vty->candidate_config = nb_config_new(NULL);
	}

	/* Execute configuration file */
	ret = config_from_file(vty, confp, &line_num);

	/* Flush any previous errors before printing messages below */
	buffer_flush_all(vty->obuf, vty->wfd);

	if (!((ret == CMD_SUCCESS) || (ret == CMD_ERR_NOTHING_TODO))) {
		const char *message = NULL;
		char *nl;

		switch (ret) {
		case CMD_ERR_AMBIGUOUS:
			message = "Ambiguous command";
			break;
		case CMD_ERR_NO_MATCH:
			message = "No such command";
			break;
		case CMD_WARNING:
			message = "Command returned Warning";
			break;
		case CMD_WARNING_CONFIG_FAILED:
			message = "Command returned Warning Config Failed";
			break;
		case CMD_ERR_INCOMPLETE:
			message = "Command returned Incomplete";
			break;
		case CMD_ERR_EXEED_ARGC_MAX:
			message =
				"Command exceeded maximum number of Arguments";
			break;
		default:
			message = "Command returned unhandled error message";
			break;
		}

		for (ALL_LIST_ELEMENTS_RO(vty->error, node, ve)) {
			nl = strchr(ve->error_buf, '\n');
			if (nl)
				*nl = '\0';
			flog_err(EC_LIB_VTY, "ERROR: %s on config line %u: %s",
				 message, ve->line_num, ve->error_buf);
		}
	}

	/*
	 * Automatically commit the candidate configuration after
	 * reading the configuration file.
	 */
	if (config == NULL) {
		ret = nb_candidate_commit(vty->candidate_config, NB_CLIENT_CLI,
					  vty, true, "Read configuration file",
					  NULL);
		if (ret != NB_OK && ret != NB_ERR_NO_CHANGES)
			zlog_err("%s: failed to read configuration file.",
				 __func__);
	}

	vty_close(vty);
}

static FILE *vty_use_backup_config(const char *fullpath)
{
	char *fullpath_sav, *fullpath_tmp;
	FILE *ret = NULL;
	int tmp, sav;
	int c;
	char buffer[512];

	size_t fullpath_sav_sz = strlen(fullpath) + strlen(CONF_BACKUP_EXT) + 1;
	fullpath_sav = malloc(fullpath_sav_sz);
	strlcpy(fullpath_sav, fullpath, fullpath_sav_sz);
	strlcat(fullpath_sav, CONF_BACKUP_EXT, fullpath_sav_sz);

	sav = open(fullpath_sav, O_RDONLY);
	if (sav < 0) {
		free(fullpath_sav);
		return NULL;
	}

	fullpath_tmp = malloc(strlen(fullpath) + 8);
	sprintf(fullpath_tmp, "%s.XXXXXX", fullpath);

	/* Open file to configuration write. */
	tmp = mkstemp(fullpath_tmp);
	if (tmp < 0)
		goto out_close_sav;

	if (fchmod(tmp, CONFIGFILE_MASK) != 0)
		goto out_close;

	while ((c = read(sav, buffer, 512)) > 0) {
		if (write(tmp, buffer, c) <= 0)
			goto out_close;
	}
	close(sav);
	close(tmp);

	if (rename(fullpath_tmp, fullpath) == 0)
		ret = fopen(fullpath, "r");
	else
		unlink(fullpath_tmp);

	if (0) {
	out_close:
		close(tmp);
		unlink(fullpath_tmp);
	out_close_sav:
		close(sav);
	}

	free(fullpath_sav);
	free(fullpath_tmp);
	return ret;
}

/* Read up configuration file from file_name. */
bool vty_read_config(struct nb_config *config, const char *config_file,
		     char *config_default_dir)
{
	char cwd[MAXPATHLEN];
	FILE *confp = NULL;
	const char *fullpath;
	char *tmp = NULL;
	bool read_success = false;

	/* If -f flag specified. */
	if (config_file != NULL) {
		if (!IS_DIRECTORY_SEP(config_file[0])) {
			if (getcwd(cwd, MAXPATHLEN) == NULL) {
				flog_err_sys(
					EC_LIB_SYSTEM_CALL,
					"%s: failure to determine Current Working Directory %d!",
					__func__, errno);
				goto tmp_free_and_out;
			}
			tmp = XMALLOC(MTYPE_TMP,
				      strlen(cwd) + strlen(config_file) + 2);
			sprintf(tmp, "%s/%s", cwd, config_file);
			fullpath = tmp;
		} else
			fullpath = config_file;

		confp = fopen(fullpath, "r");

		if (confp == NULL) {
			flog_warn(
				EC_LIB_BACKUP_CONFIG,
				"%s: failed to open configuration file %s: %s, checking backup",
				__func__, fullpath, safe_strerror(errno));

			confp = vty_use_backup_config(fullpath);
			if (confp)
				flog_warn(
					EC_LIB_BACKUP_CONFIG,
					"WARNING: using backup configuration file!");
			else {
				flog_err(
					EC_LIB_VTY,
					"%s: can't open configuration file [%s]",
					__func__, config_file);
				goto tmp_free_and_out;
			}
		}
	} else {

		host_config_set(config_default_dir);

#ifdef VTYSH
		int ret;
		struct stat conf_stat;

		/* !!!!PLEASE LEAVE!!!!
		 * This is NEEDED for use with vtysh -b, or else you can get
		 * a real configuration food fight with a lot garbage in the
		 * merged configuration file it creates coming from the per
		 * daemon configuration files.  This also allows the daemons
		 * to start if there default configuration file is not
		 * present or ignore them, as needed when using vtysh -b to
		 * configure the daemons at boot - MAG
		 */

		/* Stat for vtysh Zebra.conf, if found startup and wait for
		 * boot configuration
		 */

		if (strstr(config_default_dir, "vtysh") == NULL) {
			ret = stat(integrate_default, &conf_stat);
			if (ret >= 0) {
				read_success = true;
				goto tmp_free_and_out;
			}
		}
#endif /* VTYSH */
		confp = fopen(config_default_dir, "r");
		if (confp == NULL) {
			flog_err(
				EC_LIB_SYSTEM_CALL,
				"%s: failed to open configuration file %s: %s, checking backup",
				__func__, config_default_dir,
				safe_strerror(errno));

			confp = vty_use_backup_config(config_default_dir);
			if (confp) {
				flog_warn(
					EC_LIB_BACKUP_CONFIG,
					"WARNING: using backup configuration file!");
				fullpath = config_default_dir;
			} else {
				flog_err(EC_LIB_VTY,
					 "can't open configuration file [%s]",
					 config_default_dir);
				goto tmp_free_and_out;
			}
		} else
			fullpath = config_default_dir;
	}

	vty_read_file(config, confp);
	read_success = true;

	fclose(confp);

	host_config_set(fullpath);

tmp_free_and_out:
	XFREE(MTYPE_TMP, tmp);

	return read_success;
}

/* Small utility function which output log to the VTY. */
void vty_log(const char *level, const char *proto_str, const char *msg,
	     struct timestamp_control *ctl)
{
	unsigned int i;
	struct vty *vty;

	if (!vtyvec)
		return;

	for (i = 0; i < vector_active(vtyvec); i++)
		if ((vty = vector_slot(vtyvec, i)) != NULL)
			if (vty->monitor)
				vty_log_out(vty, level, proto_str, msg, ctl);
}

/* Async-signal-safe version of vty_log for fixed strings. */
void vty_log_fixed(char *buf, size_t len)
{
	unsigned int i;
	struct iovec iov[2];
	char crlf[4] = "\r\n";

	/* vty may not have been initialised */
	if (!vtyvec)
		return;

	iov[0].iov_base = buf;
	iov[0].iov_len = len;
	iov[1].iov_base = crlf;
	iov[1].iov_len = 2;

	for (i = 0; i < vector_active(vtyvec); i++) {
		struct vty *vty;
		if (((vty = vector_slot(vtyvec, i)) != NULL) && vty->monitor)
			/* N.B. We don't care about the return code, since
			   process is
			   most likely just about to die anyway. */
			if (writev(vty->wfd, iov, 2) == -1) {
				fprintf(stderr, "Failure to writev: %d\n",
					errno);
				exit(-1);
			}
	}
}

int vty_config_enter(struct vty *vty, bool private_config, bool exclusive)
{
	if (exclusive && nb_running_lock(NB_CLIENT_CLI, vty)) {
		vty_out(vty, "%% Configuration is locked by other client\n");
		return CMD_WARNING;
	}

	vty->node = CONFIG_NODE;
	vty->config = true;
	vty->private_config = private_config;
	vty->xpath_index = 0;

	if (private_config) {
		vty->candidate_config = nb_config_dup(running_config);
		vty->candidate_config_base = nb_config_dup(running_config);
		vty_out(vty,
			"Warning: uncommitted changes will be discarded on exit.\n\n");
	} else {
		vty->candidate_config = vty_shared_candidate_config;
		if (frr_get_cli_mode() == FRR_CLI_TRANSACTIONAL)
			vty->candidate_config_base =
				nb_config_dup(running_config);
	}

	return CMD_SUCCESS;
}

void vty_config_exit(struct vty *vty)
{
	/* Check if there's a pending confirmed commit. */
	if (vty->t_confirmed_commit_timeout) {
		vty_out(vty,
			"WARNING: exiting with a pending confirmed commit. Rolling back to previous configuration.\n\n");
		nb_cli_confirmed_commit_rollback(vty);
		nb_cli_confirmed_commit_clean(vty);
	}

	(void)nb_running_unlock(NB_CLIENT_CLI, vty);

	if (vty->candidate_config) {
		if (vty->private_config)
			nb_config_free(vty->candidate_config);
		vty->candidate_config = NULL;
	}
	if (vty->candidate_config_base) {
		nb_config_free(vty->candidate_config_base);
		vty->candidate_config_base = NULL;
	}

	vty->config = false;
}

/* Master of the threads. */
static struct thread_master *vty_master;

static void vty_event(enum event event, int sock, struct vty *vty)
{
	struct thread *vty_serv_thread = NULL;

	switch (event) {
	case VTY_SERV:
		vty_serv_thread = thread_add_read(vty_master, vty_accept, vty,
						  sock, NULL);
		vector_set_index(Vvty_serv_thread, sock, vty_serv_thread);
		break;
#ifdef VTYSH
	case VTYSH_SERV:
		vty_serv_thread = thread_add_read(vty_master, vtysh_accept, vty,
						  sock, NULL);
		vector_set_index(Vvty_serv_thread, sock, vty_serv_thread);
		break;
	case VTYSH_READ:
		thread_add_read(vty_master, vtysh_read, vty, sock,
				&vty->t_read);
		break;
	case VTYSH_WRITE:
		thread_add_write(vty_master, vtysh_write, vty, sock,
				 &vty->t_write);
		break;
#endif /* VTYSH */
	case VTY_READ:
		thread_add_read(vty_master, vty_read, vty, sock, &vty->t_read);

		/* Time out treatment. */
		if (vty->v_timeout) {
			THREAD_OFF(vty->t_timeout);
			thread_add_timer(vty_master, vty_timeout, vty,
					 vty->v_timeout, &vty->t_timeout);
		}
		break;
	case VTY_WRITE:
		thread_add_write(vty_master, vty_flush, vty, sock,
				 &vty->t_write);
		break;
	case VTY_TIMEOUT_RESET:
		THREAD_OFF(vty->t_timeout);
		if (vty->v_timeout)
			thread_add_timer(vty_master, vty_timeout, vty,
					 vty->v_timeout, &vty->t_timeout);
		break;
	}
}

DEFUN_NOSH (config_who,
       config_who_cmd,
       "who",
       "Display who is on vty\n")
{
	unsigned int i;
	struct vty *v;

	for (i = 0; i < vector_active(vtyvec); i++)
		if ((v = vector_slot(vtyvec, i)) != NULL)
			vty_out(vty, "%svty[%d] connected from %s.\n",
				v->config ? "*" : " ", i, v->address);
	return CMD_SUCCESS;
}

/* Move to vty configuration mode. */
DEFUN_NOSH (line_vty,
       line_vty_cmd,
       "line vty",
       "Configure a terminal line\n"
       "Virtual terminal\n")
{
	vty->node = VTY_NODE;
	return CMD_SUCCESS;
}

/* Set time out value. */
static int exec_timeout(struct vty *vty, const char *min_str,
			const char *sec_str)
{
	unsigned long timeout = 0;

	/* min_str and sec_str are already checked by parser.  So it must be
	   all digit string. */
	if (min_str) {
		timeout = strtol(min_str, NULL, 10);
		timeout *= 60;
	}
	if (sec_str)
		timeout += strtol(sec_str, NULL, 10);

	vty_timeout_val = timeout;
	vty->v_timeout = timeout;
	vty_event(VTY_TIMEOUT_RESET, 0, vty);


	return CMD_SUCCESS;
}

DEFUN (exec_timeout_min,
       exec_timeout_min_cmd,
       "exec-timeout (0-35791)",
       "Set timeout value\n"
       "Timeout value in minutes\n")
{
	int idx_number = 1;
	return exec_timeout(vty, argv[idx_number]->arg, NULL);
}

DEFUN (exec_timeout_sec,
       exec_timeout_sec_cmd,
       "exec-timeout (0-35791) (0-2147483)",
       "Set the EXEC timeout\n"
       "Timeout in minutes\n"
       "Timeout in seconds\n")
{
	int idx_number = 1;
	int idx_number_2 = 2;
	return exec_timeout(vty, argv[idx_number]->arg,
			    argv[idx_number_2]->arg);
}

DEFUN (no_exec_timeout,
       no_exec_timeout_cmd,
       "no exec-timeout",
       NO_STR
       "Set the EXEC timeout\n")
{
	return exec_timeout(vty, NULL, NULL);
}

/* Set vty access class. */
DEFUN (vty_access_class,
       vty_access_class_cmd,
       "access-class WORD",
       "Filter connections based on an IP access list\n"
       "IP access list\n")
{
	int idx_word = 1;
	if (vty_accesslist_name)
		XFREE(MTYPE_VTY, vty_accesslist_name);

	vty_accesslist_name = XSTRDUP(MTYPE_VTY, argv[idx_word]->arg);

	return CMD_SUCCESS;
}

/* Clear vty access class. */
DEFUN (no_vty_access_class,
       no_vty_access_class_cmd,
       "no access-class [WORD]",
       NO_STR
       "Filter connections based on an IP access list\n"
       "IP access list\n")
{
	int idx_word = 2;
	const char *accesslist = (argc == 3) ? argv[idx_word]->arg : NULL;
	if (!vty_accesslist_name
	    || (argc == 3 && strcmp(vty_accesslist_name, accesslist))) {
		vty_out(vty, "Access-class is not currently applied to vty\n");
		return CMD_WARNING_CONFIG_FAILED;
	}

	XFREE(MTYPE_VTY, vty_accesslist_name);

	vty_accesslist_name = NULL;

	return CMD_SUCCESS;
}

/* Set vty access class. */
DEFUN (vty_ipv6_access_class,
       vty_ipv6_access_class_cmd,
       "ipv6 access-class WORD",
       IPV6_STR
       "Filter connections based on an IP access list\n"
       "IPv6 access list\n")
{
	int idx_word = 2;
	if (vty_ipv6_accesslist_name)
		XFREE(MTYPE_VTY, vty_ipv6_accesslist_name);

	vty_ipv6_accesslist_name = XSTRDUP(MTYPE_VTY, argv[idx_word]->arg);

	return CMD_SUCCESS;
}

/* Clear vty access class. */
DEFUN (no_vty_ipv6_access_class,
       no_vty_ipv6_access_class_cmd,
       "no ipv6 access-class [WORD]",
       NO_STR
       IPV6_STR
       "Filter connections based on an IP access list\n"
       "IPv6 access list\n")
{
	int idx_word = 3;
	const char *accesslist = (argc == 4) ? argv[idx_word]->arg : NULL;

	if (!vty_ipv6_accesslist_name
	    || (argc == 4 && strcmp(vty_ipv6_accesslist_name, accesslist))) {
		vty_out(vty,
			"IPv6 access-class is not currently applied to vty\n");
		return CMD_WARNING_CONFIG_FAILED;
	}

	XFREE(MTYPE_VTY, vty_ipv6_accesslist_name);

	vty_ipv6_accesslist_name = NULL;

	return CMD_SUCCESS;
}

/* vty login. */
DEFUN (vty_login,
       vty_login_cmd,
       "login",
       "Enable password checking\n")
{
	no_password_check = 0;
	return CMD_SUCCESS;
}

DEFUN (no_vty_login,
       no_vty_login_cmd,
       "no login",
       NO_STR
       "Enable password checking\n")
{
	no_password_check = 1;
	return CMD_SUCCESS;
}

DEFUN (service_advanced_vty,
       service_advanced_vty_cmd,
       "service advanced-vty",
       "Set up miscellaneous service\n"
       "Enable advanced mode vty interface\n")
{
	host.advanced = 1;
	return CMD_SUCCESS;
}

DEFUN (no_service_advanced_vty,
       no_service_advanced_vty_cmd,
       "no service advanced-vty",
       NO_STR
       "Set up miscellaneous service\n"
       "Enable advanced mode vty interface\n")
{
	host.advanced = 0;
	return CMD_SUCCESS;
}

DEFUN_NOSH (terminal_monitor,
       terminal_monitor_cmd,
       "terminal monitor",
       "Set terminal line parameters\n"
       "Copy debug output to the current terminal line\n")
{
	vty->monitor = 1;
	return CMD_SUCCESS;
}

DEFUN_NOSH (terminal_no_monitor,
       terminal_no_monitor_cmd,
       "terminal no monitor",
       "Set terminal line parameters\n"
       NO_STR
       "Copy debug output to the current terminal line\n")
{
	vty->monitor = 0;
	return CMD_SUCCESS;
}

DEFUN_NOSH (no_terminal_monitor,
       no_terminal_monitor_cmd,
       "no terminal monitor",
       NO_STR
       "Set terminal line parameters\n"
       "Copy debug output to the current terminal line\n")
{
	return terminal_no_monitor(self, vty, argc, argv);
}


DEFUN_NOSH (show_history,
       show_history_cmd,
       "show history",
       SHOW_STR
       "Display the session command history\n")
{
	int index;

	for (index = vty->hindex + 1; index != vty->hindex;) {
		if (index == VTY_MAXHIST) {
			index = 0;
			continue;
		}

		if (vty->hist[index] != NULL)
			vty_out(vty, "  %s\n", vty->hist[index]);

		index++;
	}

	return CMD_SUCCESS;
}

/* vty login. */
DEFPY (log_commands,
       log_commands_cmd,
       "[no] log commands",
       NO_STR
       "Logging control\n"
       "Log all commands\n")
{
	if (no) {
		if (do_log_commands_perm) {
			vty_out(vty,
				"Daemon started with permanent logging turned on for commands, ignoring\n");
			return CMD_WARNING;
		}

		do_log_commands = false;
	} else
		do_log_commands = true;

	return CMD_SUCCESS;
}

/* Display current configuration. */
static int vty_config_write(struct vty *vty)
{
	vty_out(vty, "line vty\n");

	if (vty_accesslist_name)
		vty_out(vty, " access-class %s\n", vty_accesslist_name);

	if (vty_ipv6_accesslist_name)
		vty_out(vty, " ipv6 access-class %s\n",
			vty_ipv6_accesslist_name);

	/* exec-timeout */
	if (vty_timeout_val != VTY_TIMEOUT_DEFAULT)
		vty_out(vty, " exec-timeout %ld %ld\n", vty_timeout_val / 60,
			vty_timeout_val % 60);

	/* login */
	if (no_password_check)
		vty_out(vty, " no login\n");

	if (do_log_commands)
		vty_out(vty, "log commands\n");

	vty_out(vty, "!\n");

	return CMD_SUCCESS;
}

struct cmd_node vty_node = {
	.node = VTY_NODE,
	.prompt = "%s(config-line)# ",
};

/* Reset all VTY status. */
void vty_reset(void)
{
	unsigned int i;
	struct vty *vty;
	struct thread *vty_serv_thread;

	for (i = 0; i < vector_active(vtyvec); i++)
		if ((vty = vector_slot(vtyvec, i)) != NULL) {
			buffer_reset(vty->lbuf);
			buffer_reset(vty->obuf);
			vty->status = VTY_CLOSE;
			vty_close(vty);
		}

	for (i = 0; i < vector_active(Vvty_serv_thread); i++)
		if ((vty_serv_thread = vector_slot(Vvty_serv_thread, i))
		    != NULL) {
			THREAD_OFF(vty_serv_thread);
			vector_slot(Vvty_serv_thread, i) = NULL;
			close(i);
		}

	vty_timeout_val = VTY_TIMEOUT_DEFAULT;

	XFREE(MTYPE_VTY, vty_accesslist_name);
	XFREE(MTYPE_VTY, vty_ipv6_accesslist_name);
}

static void vty_save_cwd(void)
{
	char *c;

	c = getcwd(vty_cwd, sizeof(vty_cwd));

	if (!c) {
		/*
		 * At this point if these go wrong, more than likely
		 * the whole world is coming down around us
		 * Hence not worrying about it too much.
		 */
		if (!chdir(SYSCONFDIR)) {
			flog_err_sys(EC_LIB_SYSTEM_CALL,
				     "Failure to chdir to %s, errno: %d",
				     SYSCONFDIR, errno);
			exit(-1);
		}
		if (getcwd(vty_cwd, sizeof(vty_cwd)) == NULL) {
			flog_err_sys(EC_LIB_SYSTEM_CALL,
				     "Failure to getcwd, errno: %d", errno);
			exit(-1);
		}
	}
}

char *vty_get_cwd(void)
{
	return vty_cwd;
}

int vty_shell(struct vty *vty)
{
	return vty->type == VTY_SHELL ? 1 : 0;
}

int vty_shell_serv(struct vty *vty)
{
	return vty->type == VTY_SHELL_SERV ? 1 : 0;
}

void vty_init_vtysh(void)
{
	vtyvec = vector_init(VECTOR_MIN_SIZE);
}

/* Install vty's own commands like `who' command. */
void vty_init(struct thread_master *master_thread, bool do_command_logging)
{
	/* For further configuration read, preserve current directory. */
	vty_save_cwd();

	vtyvec = vector_init(VECTOR_MIN_SIZE);

	vty_master = master_thread;

	atexit(vty_stdio_atexit);

	/* Initilize server thread vector. */
	Vvty_serv_thread = vector_init(VECTOR_MIN_SIZE);

	/* Install bgp top node. */
	install_node(&vty_node, vty_config_write);

	install_element(VIEW_NODE, &config_who_cmd);
	install_element(VIEW_NODE, &show_history_cmd);
	install_element(CONFIG_NODE, &line_vty_cmd);
	install_element(CONFIG_NODE, &service_advanced_vty_cmd);
	install_element(CONFIG_NODE, &no_service_advanced_vty_cmd);
	install_element(CONFIG_NODE, &show_history_cmd);
	install_element(CONFIG_NODE, &log_commands_cmd);

	if (do_command_logging) {
		do_log_commands = true;
		do_log_commands_perm = true;
	}

	install_element(ENABLE_NODE, &terminal_monitor_cmd);
	install_element(ENABLE_NODE, &terminal_no_monitor_cmd);
	install_element(ENABLE_NODE, &no_terminal_monitor_cmd);

	install_default(VTY_NODE);
	install_element(VTY_NODE, &exec_timeout_min_cmd);
	install_element(VTY_NODE, &exec_timeout_sec_cmd);
	install_element(VTY_NODE, &no_exec_timeout_cmd);
	install_element(VTY_NODE, &vty_access_class_cmd);
	install_element(VTY_NODE, &no_vty_access_class_cmd);
	install_element(VTY_NODE, &vty_login_cmd);
	install_element(VTY_NODE, &no_vty_login_cmd);
	install_element(VTY_NODE, &vty_ipv6_access_class_cmd);
	install_element(VTY_NODE, &no_vty_ipv6_access_class_cmd);
}

void vty_terminate(void)
{
	memset(vty_cwd, 0x00, sizeof(vty_cwd));

	if (vtyvec && Vvty_serv_thread) {
		vty_reset();
		vector_free(vtyvec);
		vector_free(Vvty_serv_thread);
		vtyvec = NULL;
		Vvty_serv_thread = NULL;
	}
}