2 * SPDX-License-Identifier: ISC
4 * Copyright (c) 2004 by Internet Systems Consortium, Inc. ("ISC")
5 * Copyright (c) 1996-1999 by Internet Software Consortium.
7 * Permission to use, copy, modify, and distribute this software for any
8 * purpose with or without fee is hereby granted, provided that the above
9 * copyright notice and this permission notice appear in all copies.
11 * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES
12 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
13 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL ISC BE LIABLE FOR
14 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
15 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
16 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT
17 * OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
20 #if defined(LIBC_SCCS) && !defined(lint)
21 static const char rcsid[] = "$Id: inet_ntop.c,v 1.5 2005/11/03 22:59:52 marka Exp $";
22 #endif /* LIBC_SCCS and not lint */
23 #include <sys/cdefs.h>
24 __FBSDID("$FreeBSD$");
26 #include "port_before.h"
28 #include <sys/param.h>
29 #include <sys/socket.h>
31 #include <netinet/in.h>
32 #include <arpa/inet.h>
33 #include <arpa/nameser.h>
39 #include "port_after.h"
42 * WARNING: Don't even consider trying to compile this on a system where
43 * sizeof(int) < 4. sizeof(int) > 4 is fine; all the world's not a VAX.
46 static const char *inet_ntop4(const u_char *src, char *dst, socklen_t size);
47 static const char *inet_ntop6(const u_char *src, char *dst, socklen_t size);
50 * inet_ntop(af, src, dst, size)
51 * convert a network format address to presentation format.
53 * pointer to presentation format address (`dst'), or NULL (see errno).
58 inet_ntop(int af, const void * __restrict src, char * __restrict dst,
63 return (inet_ntop4(src, dst, size));
65 return (inet_ntop6(src, dst, size));
74 * inet_ntop4(src, dst, size)
75 * format an IPv4 address
80 * (2) takes a u_char* not an in_addr as input
85 inet_ntop4(const u_char *src, char *dst, socklen_t size)
87 static const char fmt[] = "%u.%u.%u.%u";
88 char tmp[sizeof "255.255.255.255"];
91 l = snprintf(tmp, sizeof(tmp), fmt, src[0], src[1], src[2], src[3]);
92 if (l <= 0 || (socklen_t) l >= size) {
96 strlcpy(dst, tmp, size);
101 * inet_ntop6(src, dst, size)
102 * convert IPv6 binary address into presentation (printable) format
107 inet_ntop6(const u_char *src, char *dst, socklen_t size)
110 * Note that int32_t and int16_t need only be "at least" large enough
111 * to contain a value of the specified size. On some systems, like
112 * Crays, there is no such thing as an integer variable with 16 bits.
113 * Keep this in mind if you think this function should have been coded
114 * to use pointer overlays. All the world's not a VAX.
116 char tmp[sizeof "ffff:ffff:ffff:ffff:ffff:ffff:255.255.255.255"], *tp;
117 struct { int base, len; } best, cur;
118 u_int words[NS_IN6ADDRSZ / NS_INT16SZ];
123 * Copy the input (bytewise) array into a wordwise array.
124 * Find the longest run of 0x00's in src[] for :: shorthanding.
126 memset(words, '\0', sizeof words);
127 for (i = 0; i < NS_IN6ADDRSZ; i++)
128 words[i / 2] |= (src[i] << ((1 - (i % 2)) << 3));
133 for (i = 0; i < (NS_IN6ADDRSZ / NS_INT16SZ); i++) {
136 cur.base = i, cur.len = 1;
140 if (cur.base != -1) {
141 if (best.base == -1 || cur.len > best.len)
147 if (cur.base != -1) {
148 if (best.base == -1 || cur.len > best.len)
151 if (best.base != -1 && best.len < 2)
158 for (i = 0; i < (NS_IN6ADDRSZ / NS_INT16SZ); i++) {
159 /* Are we inside the best run of 0x00's? */
160 if (best.base != -1 && i >= best.base &&
161 i < (best.base + best.len)) {
166 /* Are we following an initial run of 0x00s or any real hex? */
169 /* Is this address an encapsulated IPv4? */
170 if (i == 6 && best.base == 0 && (best.len == 6 ||
171 (best.len == 7 && words[7] != 0x0001) ||
172 (best.len == 5 && words[5] == 0xffff))) {
173 if (!inet_ntop4(src+12, tp, sizeof tmp - (tp - tmp))) {
180 tp += sprintf(tp, "%x", words[i]);
182 /* Was it a trailing run of 0x00's? */
183 if (best.base != -1 && (best.base + best.len) ==
184 (NS_IN6ADDRSZ / NS_INT16SZ))
189 * Check for overflow, copy, and we're done.
191 if ((socklen_t)(tp - tmp) > size) {
200 * Weak aliases for applications that use certain private entry points,
201 * and fail to include <arpa/inet.h>.
204 __weak_reference(__inet_ntop, inet_ntop);