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
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
33 static char *inet_ntop4(const u_char *src, char *dst, socklen_t size);
34 static 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 */
44 const char *
inet_ntop(int af,const void * src,char * dst,socklen_t size)45 inet_ntop(int af, const void *src, char *dst, socklen_t size)
46 {
47 memset(dst, 0, size);
48 switch (af) {
49 case AF_INET:
50 return inet_ntop4(src, dst, size);
51 case AF_INET6:
52 return inet_ntop6(src, dst, size);
53 default:
54 return NULL;
55 }
56 /* NOTREACHED */
57 }
58
59 /* const char *
60 * inet_ntop4(src, dst, size)
61 * format an IPv4 address
62 * return:
63 * `dst' (as a const)
64 * notes:
65 * (1) uses no statics
66 * (2) takes a u_char* not an in_addr as input
67 * author:
68 * Paul Vixie, 1996.
69 */
70 static char *
inet_ntop4(const u_char * src,char * dst,socklen_t size)71 inet_ntop4(const u_char *src, char *dst, socklen_t size)
72 {
73 static const char fmt[] = "%u.%u.%u.%u";
74 char tmp[sizeof "255.255.255.255"];
75 int l;
76
77 l = snprintf(tmp, sizeof(tmp), fmt, src[0], src[1], src[2], src[3]);
78 if (l <= 0 || (socklen_t) l >= size) {
79 return NULL;
80 }
81 strlcpy(dst, tmp, size);
82 return dst;
83 }
84
85 /* const char *
86 * inet_ntop6(src, dst, size)
87 * convert IPv6 binary address into presentation (printable) format
88 * author:
89 * Paul Vixie, 1996.
90 */
91 static char *
inet_ntop6(const u_char * src,char * dst,socklen_t size)92 inet_ntop6(const u_char *src, char *dst, socklen_t size)
93 {
94 /*
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.
100 */
101 char tmp[sizeof "ffff:ffff:ffff:ffff:ffff:ffff:255.255.255.255"], *tp;
102 struct { int base, len; } best, cur;
103 #define NS_IN6ADDRSZ 16
104 #define NS_INT16SZ 2
105 u_int words[NS_IN6ADDRSZ / NS_INT16SZ];
106 int i;
107
108 /*
109 * Preprocess:
110 * Copy the input (bytewise) array into a wordwise array.
111 * Find the longest run of 0x00's in src[] for :: shorthanding.
112 */
113 memset(words, '\0', sizeof words);
114 for (i = 0; i < NS_IN6ADDRSZ; i++) {
115 words[i / 2] |= (src[i] << ((1 - (i % 2)) << 3));
116 }
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;
125 cur.len = 1;
126 } else {
127 cur.len++;
128 }
129 } else {
130 if (cur.base != -1) {
131 if (best.base == -1 || cur.len > best.len) {
132 best = cur;
133 }
134 cur.base = -1;
135 }
136 }
137 }
138 if (cur.base != -1) {
139 if (best.base == -1 || cur.len > best.len) {
140 best = cur;
141 }
142 }
143 if (best.base != -1 && best.len < 2) {
144 best.base = -1;
145 }
146
147 /*
148 * Format the result.
149 */
150 tp = tmp;
151 for (i = 0; i < (NS_IN6ADDRSZ / NS_INT16SZ); i++) {
152 /* Are we inside the best run of 0x00's? */
153 if (best.base != -1 && i >= best.base &&
154 i < (best.base + best.len)) {
155 if (i == best.base) {
156 *tp++ = ':';
157 }
158 continue;
159 }
160 /* Are we following an initial run of 0x00s or any real hex? */
161 if (i != 0) {
162 *tp++ = ':';
163 }
164 /* Is this address an encapsulated IPv4? */
165 if (i == 6 && best.base == 0 && (best.len == 6 ||
166 (best.len == 7 && words[7] != 0x0001) ||
167 (best.len == 5 && words[5] == 0xffff))) {
168 if (!inet_ntop4(src + 12, tp,
169 (socklen_t)(sizeof tmp - (tp - tmp)))) {
170 return NULL;
171 }
172 tp += strlen(tp);
173 break;
174 }
175 tp += scnprintf(tp, sizeof(tmp), "%x", words[i]);
176 }
177 /* Was it a trailing run of 0x00's? */
178 if (best.base != -1 && (best.base + best.len) ==
179 (NS_IN6ADDRSZ / NS_INT16SZ)) {
180 *tp++ = ':';
181 }
182 *tp++ = '\0';
183
184 /*
185 * Check for overflow, copy, and we're done.
186 */
187 if ((socklen_t)(tp - tmp) > size) {
188 return NULL;
189 }
190 strlcpy(dst, tmp, size);
191 return dst;
192 }
193
194 /*! \file */
195