basic/in-addr-util: add IN_ADDR_PREFIX_TO_STRING

2 files changed, 45 insertions, 24 deletions

diff --git a/src/basic/in-addr-util.c b/src/basic/in-addr-util.c
index 6bf017260b..6f8ffaf259 100644
--- a/src/basic/in-addr-util.c
+++ b/src/basic/in-addr-util.c
@@ -14,6 +14,7 @@
 #include "macro.h"
 #include "parse-util.h"
 #include "random-util.h"
+#include "stdio-util.h"
 #include "string-util.h"
 #include "strxcpyx.h"
 #include "util.h"
@@ -451,34 +452,26 @@ int in_addr_to_string(int family, const union in_addr_union *u, char **ret) {
         return 0;
 }
 
-int in_addr_prefix_to_string(int family, const union in_addr_union *u, unsigned prefixlen, char **ret) {
-        _cleanup_free_ char *x = NULL;
-        char *p;
-        size_t l;
+int in_addr_prefix_to_string(
+                int family,
+                const union in_addr_union *u,
+                unsigned prefixlen,
+                char *buf,
+                size_t buf_len) {
 
         assert(u);
-        assert(ret);
+        assert(buf);
 
-        if (family == AF_INET)
-                l = INET_ADDRSTRLEN + 1 + DECIMAL_STR_MAX(unsigned);
-        else if (family == AF_INET6)
-                l = INET6_ADDRSTRLEN + 1 + DECIMAL_STR_MAX(unsigned);
-        else
+        if (!IN_SET(family, AF_INET, AF_INET6))
                 return -EAFNOSUPPORT;
 
-        x = new(char, l);
-        if (!x)
-                return -ENOMEM;
-
         errno = 0;
-        if (!inet_ntop(family, u, x, l))
-                return errno_or_else(EINVAL);
+        if (!typesafe_inet_ntop(family, u, buf, buf_len))
+                return errno_or_else(ENOSPC);
 
-        p = x + strlen(x);
-        l -= strlen(x);
-        (void) strpcpyf(&p, l, "/%u", prefixlen);
-
-        *ret = TAKE_PTR(x);
+        size_t l = strlen(buf);
+        if (!snprintf_ok(buf + l, buf_len - l, "/%u", prefixlen))
+                return -ENOSPC;
         return 0;
 }
 
diff --git a/src/basic/in-addr-util.h b/src/basic/in-addr-util.h
index 89d0505c13..c1e7ef965d 100644
--- a/src/basic/in-addr-util.h
+++ b/src/basic/in-addr-util.h
@@ -93,10 +93,38 @@ static inline const char* typesafe_inet_ntop6(const struct in6_addr *a, char *bu
 #define IN4_ADDR_TO_STRING(addr) typesafe_inet_ntop4(addr, (char[INET_ADDRSTRLEN]){}, INET_ADDRSTRLEN)
 #define IN6_ADDR_TO_STRING(addr) typesafe_inet_ntop6(addr, (char[INET6_ADDRSTRLEN]){}, INET6_ADDRSTRLEN)
 
-int in_addr_prefix_to_string(int family, const union in_addr_union *u, unsigned prefixlen, char **ret);
-static inline int in6_addr_prefix_to_string(const struct in6_addr *u, unsigned prefixlen, char **ret) {
-        return in_addr_prefix_to_string(AF_INET6, (const union in_addr_union*) u, prefixlen, ret);
+int in_addr_prefix_to_string(
+                int family,
+                const union in_addr_union *u,
+                unsigned prefixlen,
+                char *buf,
+                size_t buf_len);
+
+static inline const char* _in_addr_prefix_to_string(
+                int family,
+                const union in_addr_union *u,
+                unsigned prefixlen,
+                char *buf,
+                size_t buf_len) {
+        /* We assume that this is called with an appropriately sized buffer and can never fail. */
+        assert_se(in_addr_prefix_to_string(family, u, prefixlen, buf, buf_len) == 0);
+        return buf;
 }
+static inline const char* _in4_addr_prefix_to_string(const struct in_addr *a, unsigned prefixlen, char *buf, size_t buf_len) {
+        return _in_addr_prefix_to_string(AF_INET, (const union in_addr_union *) a, prefixlen, buf, buf_len);
+}
+static inline const char* _in6_addr_prefix_to_string(const struct in6_addr *a, unsigned prefixlen, char *buf, size_t buf_len) {
+        return _in_addr_prefix_to_string(AF_INET6, (const union in_addr_union *) a, prefixlen, buf, buf_len);
+}
+
+#define PREFIX_SUFFIX_MAX (1 + DECIMAL_STR_MAX(unsigned))
+#define IN_ADDR_PREFIX_TO_STRING(family, addr, prefixlen) \
+        _in_addr_prefix_to_string(family, addr, prefixlen, (char[IN_ADDR_MAX + PREFIX_SUFFIX_MAX]){}, IN_ADDR_MAX + PREFIX_SUFFIX_MAX)
+#define IN4_ADDR_PREFIX_TO_STRING(addr, prefixlen) \
+        _in4_addr_prefix_to_string(addr, prefixlen, (char[INET_ADDRSTRLEN + PREFIX_SUFFIX_MAX]){}, INET_ADDRSTRLEN + PREFIX_SUFFIX_MAX)
+#define IN6_ADDR_PREFIX_TO_STRING(addr, prefixlen) \
+        _in6_addr_prefix_to_string(addr, prefixlen, (char[INET6_ADDRSTRLEN + PREFIX_SUFFIX_MAX]){}, INET6_ADDRSTRLEN + PREFIX_SUFFIX_MAX)
+
 int in_addr_port_ifindex_name_to_string(int family, const union in_addr_union *u, uint16_t port, int ifindex, const char *server_name, char **ret);
 static inline int in_addr_ifindex_to_string(int family, const union in_addr_union *u, int ifindex, char **ret) {
         return in_addr_port_ifindex_name_to_string(family, u, 0, ifindex, NULL, ret);