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)
19 static const char rcsid[] = "$Id: inet_ntop.c,v 1.3.18.2 2005/11/03 23:02:22 marka Exp $";
20 #endif /* LIBC_SCCS and not lint */
21 #include <sys/cdefs.h>
22 __FBSDID("$FreeBSD$");
23
24 #include <sys/param.h>
25 #include <sys/socket.h>
26 #include <sys/systm.h>
27
28 #include <netinet/in.h>
29
30 /*%
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.
33 */
34
35 static char *inet_ntop4(const u_char *src, char *dst, socklen_t size);
36 static char *inet_ntop6(const u_char *src, char *dst, socklen_t size);
37
38 /* char *
39 * inet_ntop(af, src, dst, size)
40 * convert a network format address to presentation format.
41 * return:
42 * pointer to presentation format address (`dst'), or NULL (see errno).
43 * author:
44 * Paul Vixie, 1996.
45 */
46 char *
47 inet_ntop(int af, const void *src, char *dst, socklen_t size)
48 {
49 switch (af) {
50 case AF_INET:
51 return (inet_ntop4(src, dst, size));
52 case AF_INET6:
53 return (inet_ntop6(src, dst, size));
54 default:
55 return (NULL);
56 }
57 /* NOTREACHED */
58 }
59
60 /* const char *
61 * inet_ntop4(src, dst, size)
62 * format an IPv4 address
63 * return:
64 * `dst' (as a const)
65 * notes:
66 * (1) uses no statics
67 * (2) takes a u_char* not an in_addr as input
68 * author:
69 * Paul Vixie, 1996.
70 */
71 static char *
72 inet_ntop4(const u_char *src, char *dst, socklen_t size)
73 {
74 static const char fmt[] = "%u.%u.%u.%u";
75 char tmp[sizeof "255.255.255.255"];
76 int l;
77
78 l = snprintf(tmp, sizeof(tmp), fmt, src[0], src[1], src[2], src[3]);
79 if (l <= 0 || (socklen_t) l >= size) {
80 return (NULL);
81 }
82 strlcpy(dst, tmp, size);
83 return (dst);
84 }
85
86 /* const char *
87 * inet_ntop6(src, dst, size)
88 * convert IPv6 binary address into presentation (printable) format
89 * author:
90 * Paul Vixie, 1996.
91 */
92 static char *
93 inet_ntop6(const u_char *src, char *dst, socklen_t size)
94 {
95 /*
96 * Note that int32_t and int16_t need only be "at least" large enough
97 * to contain a value of the specified size. On some systems, like
98 * Crays, there is no such thing as an integer variable with 16 bits.
99 * Keep this in mind if you think this function should have been coded
100 * to use pointer overlays. All the world's not a VAX.
101 */
102 char tmp[sizeof "ffff:ffff:ffff:ffff:ffff:ffff:255.255.255.255"], *tp;
103 struct { int base, len; } best, cur;
104 #define NS_IN6ADDRSZ 16
105 #define NS_INT16SZ 2
106 u_int words[NS_IN6ADDRSZ / NS_INT16SZ];
107 int i;
108
109 /*
110 * Preprocess:
111 * Copy the input (bytewise) array into a wordwise array.
112 * Find the longest run of 0x00's in src[] for :: shorthanding.
113 */
114 memset(words, '\0', sizeof words);
115 for (i = 0; i < NS_IN6ADDRSZ; i++)
116 words[i / 2] |= (src[i] << ((1 - (i % 2)) << 3));
117 best.base = -1;
118 best.len = 0;
119 cur.base = -1;
120 cur.len = 0;
121 for (i = 0; i < (NS_IN6ADDRSZ / NS_INT16SZ); i++) {
122 if (words[i] == 0) {
123 if (cur.base == -1)
124 cur.base = i, cur.len = 1;
125 else
126 cur.len++;
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 += sprintf(tp, "%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 strcpy(dst, tmp);
181 return (dst);
182 }
183
184 /*! \file */
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