1/*
2 * Copyright (c) 2004 by Internet Systems Consortium, Inc. ("ISC")
3 * Copyright (c) 1996-1999 by Internet Software Consortium.
4 *
5 * Permission to use, copy, modify, and distribute this software for any
6 * purpose with or without fee is hereby granted, provided that the above
7 * copyright notice and this permission notice appear in all copies.
8 *
9 * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES
10 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
11 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL ISC BE LIABLE FOR
12 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
13 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
14 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT
15 * OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
16 */
17
18#if defined(LIBC_SCCS) && !defined(lint)
19static const char rcsid[] = "$Id: inet_ntop.c,v 1.3.18.2 2005/11/03 23:02:22 marka Exp $";
20#endif /* LIBC_SCCS and not lint */
21
22#include <sys/param.h>
23#include <sys/socket.h>
24#include <sys/systm.h>
25
26#include <netinet/in.h>
27
28/*%
29 * WARNING: Don't even consider trying to compile this on a system where
30 * sizeof(int) < 4. sizeof(int) > 4 is fine; all the world's not a VAX.
31 */
32
33static char *inet_ntop4(const u_char *src, char *dst, socklen_t size);
34static char *inet_ntop6(const u_char *src, char *dst, socklen_t size);
35
36/* char *
37 * inet_ntop(af, src, dst, size)
38 * convert a network format address to presentation format.
39 * return:
40 * pointer to presentation format address (`dst'), or NULL (see errno).
41 * author:
42 * Paul Vixie, 1996.
43 */
44const char *
45inet_ntop(int af, const void *src, char *dst, socklen_t size)
46{
47 switch (af) {
48 case AF_INET:
49 return (inet_ntop4(src, dst, size));
50 case AF_INET6:
51 return (inet_ntop6(src, dst, size));
52 default:
53 return (NULL);
54 }
55 /* NOTREACHED */
56}
57
58/* const char *
59 * inet_ntop4(src, dst, size)
60 * format an IPv4 address
61 * return:
62 * `dst' (as a const)
63 * notes:
64 * (1) uses no statics
65 * (2) takes a u_char* not an in_addr as input
66 * author:
67 * Paul Vixie, 1996.
68 */
69static char *
70inet_ntop4(const u_char *src, char *dst, socklen_t size)
71{
72 static const char fmt[] = "%u.%u.%u.%u";
73 char tmp[sizeof "255.255.255.255"];
74 int l;
75
76 l = snprintf(tmp, sizeof(tmp), fmt, src[0], src[1], src[2], src[3]);
77 if (l <= 0 || (socklen_t) l >= size) {
78 return (NULL);
79 }
80 strlcpy(dst, tmp, size);
81 return (dst);
82}
83
84/* const char *
85 * inet_ntop6(src, dst, size)
86 * convert IPv6 binary address into presentation (printable) format
87 * author:
88 * Paul Vixie, 1996.
89 */
90static char *
91inet_ntop6(const u_char *src, char *dst, socklen_t size)
92{
93 /*
94 * Note that int32_t and int16_t need only be "at least" large enough
95 * to contain a value of the specified size. On some systems, like
96 * Crays, there is no such thing as an integer variable with 16 bits.
97 * Keep this in mind if you think this function should have been coded
98 * to use pointer overlays. All the world's not a VAX.
99 */
100 char tmp[sizeof "ffff:ffff:ffff:ffff:ffff:ffff:255.255.255.255"], *tp;
101 struct { int base, len; } best, cur;
102#define NS_IN6ADDRSZ 16
103#define NS_INT16SZ 2
104 u_int words[NS_IN6ADDRSZ / NS_INT16SZ];
105 int i;
106
107 /*
108 * Preprocess:
109 * Copy the input (bytewise) array into a wordwise array.
110 * Find the longest run of 0x00's in src[] for :: shorthanding.
111 */
112 memset(words, '\0', sizeof words);
113 for (i = 0; i < NS_IN6ADDRSZ; i++)
114 words[i / 2] |= (src[i] << ((1 - (i % 2)) << 3));
115 best.base = -1;
116 best.len = 0;
117 cur.base = -1;
118 cur.len = 0;
119 for (i = 0; i < (NS_IN6ADDRSZ / NS_INT16SZ); i++) {
120 if (words[i] == 0) {
121 if (cur.base == -1) {
122 cur.base = i;
123 cur.len = 1;
124 } else {
125 cur.len++;
126 }
127 } else {
128 if (cur.base != -1) {
129 if (best.base == -1 || cur.len > best.len)
130 best = cur;
131 cur.base = -1;
132 }
133 }
134 }
135 if (cur.base != -1) {
136 if (best.base == -1 || cur.len > best.len)
137 best = cur;
138 }
139 if (best.base != -1 && best.len < 2)
140 best.base = -1;
141
142 /*
143 * Format the result.
144 */
145 tp = tmp;
146 for (i = 0; i < (NS_IN6ADDRSZ / NS_INT16SZ); i++) {
147 /* Are we inside the best run of 0x00's? */
148 if (best.base != -1 && i >= best.base &&
149 i < (best.base + best.len)) {
150 if (i == best.base)
151 *tp++ = ':';
152 continue;
153 }
154 /* Are we following an initial run of 0x00s or any real hex? */
155 if (i != 0)
156 *tp++ = ':';
157 /* Is this address an encapsulated IPv4? */
158 if (i == 6 && best.base == 0 && (best.len == 6 ||
159 (best.len == 7 && words[7] != 0x0001) ||
160 (best.len == 5 && words[5] == 0xffff))) {
161 if (!inet_ntop4(src+12, tp, sizeof tmp - (tp - tmp)))
162 return (NULL);
163 tp += strlen(tp);
164 break;
165 }
166 tp += snprintf(tp, sizeof(tmp), "%x", words[i]);
167 }
168 /* Was it a trailing run of 0x00's? */
169 if (best.base != -1 && (best.base + best.len) ==
170 (NS_IN6ADDRSZ / NS_INT16SZ))
171 *tp++ = ':';
172 *tp++ = '\0';
173
174 /*
175 * Check for overflow, copy, and we're done.
176 */
177 if ((socklen_t)(tp - tmp) > size) {
178 return (NULL);
179 }
180 strlcpy(dst, tmp, size);
181 return (dst);
182}
183
184/*! \file */
185