1 /* $NetBSD: inet_ntop.c,v 1.9 2012/03/20 17:08:13 matt Exp $ */
2
3 /*
4 * Copyright (c) 2004 by Internet Systems Consortium, Inc. ("ISC")
5 * Copyright (c) 1996-1999 by Internet Software Consortium.
6 *
7 * Permission to use, copy, modify, and distribute this software for any
8 * purpose with or without fee is hereby granted, provided that the above
9 * copyright notice and this permission notice appear in all copies.
10 *
11 * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES
12 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
13 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL ISC BE LIABLE FOR
14 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
15 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
16 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT
17 * OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
18 */
19
20 #include <sys/cdefs.h>
21 #if defined(LIBC_SCCS) && !defined(lint)
22 #if 0
23 static const char rcsid[] = "Id: inet_ntop.c,v 1.5 2005/11/03 22:59:52 marka Exp";
24 #else
25 __RCSID("$NetBSD: inet_ntop.c,v 1.9 2012/03/20 17:08:13 matt Exp $");
26 #endif
27 #endif /* LIBC_SCCS and not lint */
28
29 #include "port_before.h"
30
31 #include "namespace.h"
32 #include <sys/param.h>
33 #include <sys/types.h>
34 #include <sys/socket.h>
35
36 #include <netinet/in.h>
37 #include <arpa/inet.h>
38 #include <arpa/nameser.h>
39
40 #include <assert.h>
41 #include <errno.h>
42 #include <stdio.h>
43 #include <stdlib.h>
44 #include <string.h>
45
46 #include "port_after.h"
47
48 #ifdef __weak_alias
49 __weak_alias(inet_ntop,_inet_ntop)
50 #endif
51
52 /*%
53 * WARNING: Don't even consider trying to compile this on a system where
54 * sizeof(int) < 4. sizeof(int) > 4 is fine; all the world's not a VAX.
55 */
56
57 static const char *inet_ntop4(const u_char *src, char *dst, socklen_t size);
58 static const char *inet_ntop6(const u_char *src, char *dst, socklen_t size);
59
60 /* char *
61 * inet_ntop(af, src, dst, size)
62 * convert a network format address to presentation format.
63 * return:
64 * pointer to presentation format address (`dst'), or NULL (see errno).
65 * author:
66 * Paul Vixie, 1996.
67 */
68 const char *
inet_ntop(int af,const void * src,char * dst,socklen_t size)69 inet_ntop(int af, const void *src, char *dst, socklen_t size)
70 {
71
72 _DIAGASSERT(src != NULL);
73 _DIAGASSERT(dst != NULL);
74
75 switch (af) {
76 case AF_INET:
77 return (inet_ntop4(src, dst, size));
78 case AF_INET6:
79 return (inet_ntop6(src, dst, size));
80 default:
81 errno = EAFNOSUPPORT;
82 return (NULL);
83 }
84 /* NOTREACHED */
85 }
86
87 /* const char *
88 * inet_ntop4(src, dst, size)
89 * format an IPv4 address, more or less like inet_ntoa()
90 * return:
91 * `dst' (as a const)
92 * notes:
93 * (1) uses no statics
94 * (2) takes a u_char* not an in_addr as input
95 * author:
96 * Paul Vixie, 1996.
97 */
98 static const char *
inet_ntop4(const u_char * src,char * dst,socklen_t size)99 inet_ntop4(const u_char *src, char *dst, socklen_t size)
100 {
101 char tmp[sizeof "255.255.255.255"];
102 int l;
103
104 _DIAGASSERT(src != NULL);
105 _DIAGASSERT(dst != NULL);
106
107 l = snprintf(tmp, sizeof(tmp), "%u.%u.%u.%u",
108 src[0], src[1], src[2], src[3]);
109 if (l <= 0 || (socklen_t) l >= size) {
110 errno = ENOSPC;
111 return (NULL);
112 }
113 strlcpy(dst, tmp, size);
114 return (dst);
115 }
116
117 /* const char *
118 * inet_ntop6(src, dst, size)
119 * convert IPv6 binary address into presentation (printable) format
120 * author:
121 * Paul Vixie, 1996.
122 */
123 static const char *
inet_ntop6(const u_char * src,char * dst,socklen_t size)124 inet_ntop6(const u_char *src, char *dst, socklen_t size)
125 {
126 /*
127 * Note that int32_t and int16_t need only be "at least" large enough
128 * to contain a value of the specified size. On some systems, like
129 * Crays, there is no such thing as an integer variable with 16 bits.
130 * Keep this in mind if you think this function should have been coded
131 * to use pointer overlays. All the world's not a VAX.
132 */
133 char tmp[sizeof "ffff:ffff:ffff:ffff:ffff:ffff:255.255.255.255"];
134 char *tp, *ep;
135 struct { int base, len; } best, cur;
136 u_int words[NS_IN6ADDRSZ / NS_INT16SZ];
137 int i;
138 int advance;
139
140 _DIAGASSERT(src != NULL);
141 _DIAGASSERT(dst != NULL);
142
143 /*
144 * Preprocess:
145 * Copy the input (bytewise) array into a wordwise array.
146 * Find the longest run of 0x00's in src[] for :: shorthanding.
147 */
148 memset(words, '\0', sizeof words);
149 for (i = 0; i < NS_IN6ADDRSZ; i++)
150 words[i / 2] |= (src[i] << ((1 - (i % 2)) << 3));
151 best.base = -1;
152 best.len = 0;
153 cur.base = -1;
154 cur.len = 0;
155 for (i = 0; i < (NS_IN6ADDRSZ / NS_INT16SZ); i++) {
156 if (words[i] == 0) {
157 if (cur.base == -1)
158 cur.base = i, cur.len = 1;
159 else
160 cur.len++;
161 } else {
162 if (cur.base != -1) {
163 if (best.base == -1 || cur.len > best.len)
164 best = cur;
165 cur.base = -1;
166 }
167 }
168 }
169 if (cur.base != -1) {
170 if (best.base == -1 || cur.len > best.len)
171 best = cur;
172 }
173 if (best.base != -1 && best.len < 2)
174 best.base = -1;
175
176 /*
177 * Format the result.
178 */
179 tp = tmp;
180 ep = tmp + sizeof(tmp);
181 for (i = 0; i < (NS_IN6ADDRSZ / NS_INT16SZ); i++) {
182 /* Are we inside the best run of 0x00's? */
183 if (best.base != -1 && i >= best.base &&
184 i < (best.base + best.len)) {
185 if (i == best.base)
186 *tp++ = ':';
187 continue;
188 }
189 /* Are we following an initial run of 0x00s or any real hex? */
190 if (i != 0) {
191 if (tp + 1 >= ep)
192 return (NULL);
193 *tp++ = ':';
194 }
195 /* Is this address an encapsulated IPv4? */
196 if (i == 6 && best.base == 0 &&
197 (best.len == 6 ||
198 (best.len == 7 && words[7] != 0x0001) ||
199 (best.len == 5 && words[5] == 0xffff))) {
200 if (!inet_ntop4(src+12, tp, (socklen_t)(ep - tp)))
201 return (NULL);
202 tp += strlen(tp);
203 break;
204 }
205 advance = snprintf(tp, (size_t)(ep - tp), "%x", words[i]);
206 if (advance <= 0 || advance >= ep - tp)
207 return (NULL);
208 tp += advance;
209 }
210 /* Was it a trailing run of 0x00's? */
211 if (best.base != -1 && (best.base + best.len) ==
212 (NS_IN6ADDRSZ / NS_INT16SZ)) {
213 if (tp + 1 >= ep)
214 return (NULL);
215 *tp++ = ':';
216 }
217 if (tp + 1 >= ep)
218 return (NULL);
219 *tp++ = '\0';
220
221 /*
222 * Check for overflow, copy, and we're done.
223 */
224 if ((size_t)(tp - tmp) > size) {
225 errno = ENOSPC;
226 return (NULL);
227 }
228 strlcpy(dst, tmp, size);
229 return (dst);
230 }
231
232 /*! \file */
233