1 /* Copyright (c) 1996 by Internet Software Consortium.
3 * Permission to use, copy, modify, and distribute this software for any
4 * purpose with or without fee is hereby granted, provided that the above
5 * copyright notice and this permission notice appear in all copies.
7 * THE SOFTWARE IS PROVIDED "AS IS" AND INTERNET SOFTWARE CONSORTIUM DISCLAIMS
8 * ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES
9 * OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL INTERNET SOFTWARE
10 * CONSORTIUM BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
11 * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
12 * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
13 * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
17 #if defined(LIBC_SCCS) && !defined(lint)
18 static char rcsid[] = "$Id: inet_ntop.c,v 8.7 1996/08/05 08:41:18 vixie Exp $";
19 #endif /* LIBC_SCCS and not lint */
20 #include <sys/cdefs.h>
21 __FBSDID("$FreeBSD$");
23 #include <sys/param.h>
24 #include <sys/types.h>
25 #include <sys/socket.h>
26 #include <netinet/in.h>
27 #include <arpa/inet.h>
28 #include <arpa/nameser.h>
33 #define SPRINTF(x) ((socklen_t)sprintf x)
36 * WARNING: Don't even consider trying to compile this on a system where
37 * sizeof(int) < 4. sizeof(int) > 4 is fine; all the world's not a VAX.
40 static const char *inet_ntop4(const u_char *src, char *dst, socklen_t size);
41 static const char *inet_ntop6(const u_char *src, char *dst, socklen_t size);
44 * inet_ntop(af, src, dst, size)
45 * convert a network format address to presentation format.
47 * pointer to presentation format address (`dst'), or NULL (see errno).
52 inet_ntop(af, src, dst, size)
60 return (inet_ntop4(src, dst, size));
62 return (inet_ntop6(src, dst, size));
71 * inet_ntop4(src, dst, size)
72 * format an IPv4 address, more or less like inet_ntoa()
77 * (2) takes a u_char* not an in_addr as input
82 inet_ntop4(src, dst, size)
87 static const char fmt[] = "%u.%u.%u.%u";
88 char tmp[sizeof "255.255.255.255"];
90 if (SPRINTF((tmp, fmt, src[0], src[1], src[2], src[3])) > size) {
99 * inet_ntop6(src, dst, size)
100 * convert IPv6 binary address into presentation (printable) format
105 inet_ntop6(src, dst, size)
111 * Note that int32_t and int16_t need only be "at least" large enough
112 * to contain a value of the specified size. On some systems, like
113 * Crays, there is no such thing as an integer variable with 16 bits.
114 * Keep this in mind if you think this function should have been coded
115 * to use pointer overlays. All the world's not a VAX.
117 char tmp[sizeof "ffff:ffff:ffff:ffff:ffff:ffff:255.255.255.255"], *tp;
118 struct { int base, len; } best, cur;
119 u_int words[NS_IN6ADDRSZ / NS_INT16SZ];
124 * Copy the input (bytewise) array into a wordwise array.
125 * Find the longest run of 0x00's in src[] for :: shorthanding.
127 memset(words, '\0', sizeof words);
128 for (i = 0; i < NS_IN6ADDRSZ; i++)
129 words[i / 2] |= (src[i] << ((1 - (i % 2)) << 3));
132 for (i = 0; i < (NS_IN6ADDRSZ / NS_INT16SZ); i++) {
135 cur.base = i, cur.len = 1;
139 if (cur.base != -1) {
140 if (best.base == -1 || cur.len > best.len)
146 if (cur.base != -1) {
147 if (best.base == -1 || cur.len > best.len)
150 if (best.base != -1 && best.len < 2)
157 for (i = 0; i < (NS_IN6ADDRSZ / NS_INT16SZ); i++) {
158 /* Are we inside the best run of 0x00's? */
159 if (best.base != -1 && i >= best.base &&
160 i < (best.base + best.len)) {
165 /* Are we following an initial run of 0x00s or any real hex? */
168 /* Is this address an encapsulated IPv4? */
169 if (i == 6 && best.base == 0 &&
170 (best.len == 6 || (best.len == 5 && words[5] == 0xffff))) {
171 if (!inet_ntop4(src+12, tp, sizeof tmp - (tp - tmp)))
176 tp += SPRINTF((tp, "%x", words[i]));
178 /* Was it a trailing run of 0x00's? */
179 if (best.base != -1 && (best.base + best.len) ==
180 (NS_IN6ADDRSZ / NS_INT16SZ))
185 * Check for overflow, copy, and we're done.
187 if ((socklen_t)(tp - tmp) > size) {
196 * Weak aliases for applications that use certain private entry points,
197 * and fail to include <arpa/inet.h>.
200 __weak_reference(__inet_ntop, inet_ntop);