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
16 * $FreeBSD: src/lib/libc/net/inet_ntop.c,v 1.6.2.2 2002/12/16 15:19:35 robert Exp $
17 * $DragonFly: src/lib/libc/net/inet_ntop.c,v 1.4 2005/11/13 02:04:47 swildner Exp $
20 #include <sys/param.h>
21 #include <sys/types.h>
22 #include <sys/socket.h>
23 #include <netinet/in.h>
24 #include <arpa/inet.h>
25 #include <arpa/nameser.h>
31 * WARNING: Don't even consider trying to compile this on a system where
32 * sizeof(int) < 4. sizeof(int) > 4 is fine; all the world's not a VAX.
35 static const char *inet_ntop4 (const u_char *src, char *dst, size_t size);
36 static const char *inet_ntop6 (const u_char *src, char *dst, size_t size);
39 * inet_ntop(af, src, dst, size)
40 * convert a network format address to presentation format.
42 * pointer to presentation format address (`dst'), or NULL (see errno).
47 inet_ntop(int af, const void *src, char *dst, size_t size)
51 return (inet_ntop4(src, dst, size));
53 return (inet_ntop6(src, dst, size));
62 * inet_ntop4(src, dst, size)
63 * format an IPv4 address, more or less like inet_ntoa()
68 * (2) takes a u_char* not an in_addr as input
73 inet_ntop4(const u_char *src, char *dst, size_t size)
75 static const char fmt[] = "%u.%u.%u.%u";
77 if ((size_t)snprintf(dst, size, fmt, src[0], src[1], src[2], src[3])
86 * inet_ntop6(src, dst, size)
87 * convert IPv6 binary address into presentation (printable) format
92 inet_ntop6(const u_char *src, char *dst, size_t size)
95 * Note that int32_t and int16_t need only be "at least" large enough
96 * to contain a value of the specified size. On some systems, like
97 * Crays, there is no such thing as an integer variable with 16 bits.
98 * Keep this in mind if you think this function should have been coded
99 * to use pointer overlays. All the world's not a VAX.
101 char tmp[sizeof "ffff:ffff:ffff:ffff:ffff:ffff:255.255.255.255"], *tp;
102 struct { int base, len; } best, cur;
103 u_int words[NS_IN6ADDRSZ / NS_INT16SZ];
108 * Copy the input (bytewise) array into a wordwise array.
109 * Find the longest run of 0x00's in src[] for :: shorthanding.
111 memset(words, '\0', sizeof words);
112 for (i = 0; i < NS_IN6ADDRSZ; i++)
113 words[i / 2] |= (src[i] << ((1 - (i % 2)) << 3));
116 for (i = 0; i < (NS_IN6ADDRSZ / NS_INT16SZ); i++) {
119 cur.base = i, cur.len = 1;
123 if (cur.base != -1) {
124 if (best.base == -1 || cur.len > best.len)
130 if (cur.base != -1) {
131 if (best.base == -1 || cur.len > best.len)
134 if (best.base != -1 && best.len < 2)
141 for (i = 0; i < (NS_IN6ADDRSZ / NS_INT16SZ); i++) {
142 /* Are we inside the best run of 0x00's? */
143 if (best.base != -1 && i >= best.base &&
144 i < (best.base + best.len)) {
149 /* Are we following an initial run of 0x00s or any real hex? */
152 /* Is this address an encapsulated IPv4? */
153 if (i == 6 && best.base == 0 &&
154 (best.len == 6 || (best.len == 5 && words[5] == 0xffff))) {
155 if (!inet_ntop4(src+12, tp, sizeof tmp - (tp - tmp)))
160 tp += sprintf(tp, "%x", words[i]);
162 /* Was it a trailing run of 0x00's? */
163 if (best.base != -1 && (best.base + best.len) ==
164 (NS_IN6ADDRSZ / NS_INT16SZ))
169 * Check for overflow, copy, and we're done.
171 if ((size_t)(tp - tmp) > size) {
180 * Weak aliases for applications that use certain private entry points,
181 * and fail to include <arpa/inet.h>.
184 __weak_reference(__inet_ntop, inet_ntop);