1 /* $OpenBSD: inet_ntop.c,v 1.8 2008/12/09 19:38:38 otto Exp $ */
2
3 /* Copyright (c) 1996 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 INTERNET SOFTWARE CONSORTIUM DISCLAIMS
10 * ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES
11 * OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL INTERNET SOFTWARE
12 * CONSORTIUM BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
13 * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
14 * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
15 * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
16 * SOFTWARE.
17 */
18
19 /* OPENBSD ORIGINAL: lib/libc/net/inet_ntop.c */
20
21 #include "includes.h"
22
23 #ifndef HAVE_INET_NTOP
24
25 #include <sys/types.h>
26 #include <sys/socket.h>
27 #include <netinet/in.h>
28 #include <arpa/inet.h>
29 #include <arpa/nameser.h>
30 #include <string.h>
31 #include <errno.h>
32 #include <stdio.h>
33
34 #ifndef IN6ADDRSZ
35 #define IN6ADDRSZ 16 /* IPv6 T_AAAA */
36 #endif
37
38 #ifndef INT16SZ
39 #define INT16SZ 2 /* for systems without 16-bit ints */
40 #endif
41
42 /*
43 * WARNING: Don't even consider trying to compile this on a system where
44 * sizeof(int) < 4. sizeof(int) > 4 is fine; all the world's not a VAX.
45 */
46
47 static const char *inet_ntop4(const u_char *src, char *dst, size_t size);
48 static const char *inet_ntop6(const u_char *src, char *dst, size_t size);
49
50 /* char *
51 * inet_ntop(af, src, dst, size)
52 * convert a network format address to presentation format.
53 * return:
54 * pointer to presentation format address (`dst'), or NULL (see errno).
55 * author:
56 * Paul Vixie, 1996.
57 */
58 const char *
inet_ntop(int af,const void * src,char * dst,socklen_t size)59 inet_ntop(int af, const void *src, char *dst, socklen_t size)
60 {
61 switch (af) {
62 case AF_INET:
63 return (inet_ntop4(src, dst, (size_t)size));
64 case AF_INET6:
65 return (inet_ntop6(src, dst, (size_t)size));
66 default:
67 errno = EAFNOSUPPORT;
68 return (NULL);
69 }
70 /* NOTREACHED */
71 }
72
73 /* const char *
74 * inet_ntop4(src, dst, size)
75 * format an IPv4 address, more or less like inet_ntoa()
76 * return:
77 * `dst' (as a const)
78 * notes:
79 * (1) uses no statics
80 * (2) takes a u_char* not an in_addr as input
81 * author:
82 * Paul Vixie, 1996.
83 */
84 static const char *
inet_ntop4(const u_char * src,char * dst,size_t size)85 inet_ntop4(const u_char *src, char *dst, size_t size)
86 {
87 static const char fmt[] = "%u.%u.%u.%u";
88 char tmp[sizeof "255.255.255.255"];
89 int l;
90
91 l = snprintf(tmp, size, fmt, src[0], src[1], src[2], src[3]);
92 if (l <= 0 || l >= size) {
93 errno = ENOSPC;
94 return (NULL);
95 }
96 strlcpy(dst, tmp, size);
97 return (dst);
98 }
99
100 /* const char *
101 * inet_ntop6(src, dst, size)
102 * convert IPv6 binary address into presentation (printable) format
103 * author:
104 * Paul Vixie, 1996.
105 */
106 static const char *
inet_ntop6(const u_char * src,char * dst,size_t size)107 inet_ntop6(const u_char *src, char *dst, size_t size)
108 {
109 /*
110 * Note that int32_t and int16_t need only be "at least" large enough
111 * to contain a value of the specified size. On some systems, like
112 * Crays, there is no such thing as an integer variable with 16 bits.
113 * Keep this in mind if you think this function should have been coded
114 * to use pointer overlays. All the world's not a VAX.
115 */
116 char tmp[sizeof "ffff:ffff:ffff:ffff:ffff:ffff:255.255.255.255"];
117 char *tp, *ep;
118 struct { int base, len; } best, cur;
119 u_int words[IN6ADDRSZ / INT16SZ];
120 int i;
121 int advance;
122
123 /*
124 * Preprocess:
125 * Copy the input (bytewise) array into a wordwise array.
126 * Find the longest run of 0x00's in src[] for :: shorthanding.
127 */
128 memset(words, '\0', sizeof words);
129 for (i = 0; i < IN6ADDRSZ; i++)
130 words[i / 2] |= (src[i] << ((1 - (i % 2)) << 3));
131 best.base = -1;
132 cur.base = -1;
133 for (i = 0; i < (IN6ADDRSZ / INT16SZ); i++) {
134 if (words[i] == 0) {
135 if (cur.base == -1)
136 cur.base = i, cur.len = 1;
137 else
138 cur.len++;
139 } else {
140 if (cur.base != -1) {
141 if (best.base == -1 || cur.len > best.len)
142 best = cur;
143 cur.base = -1;
144 }
145 }
146 }
147 if (cur.base != -1) {
148 if (best.base == -1 || cur.len > best.len)
149 best = cur;
150 }
151 if (best.base != -1 && best.len < 2)
152 best.base = -1;
153
154 /*
155 * Format the result.
156 */
157 tp = tmp;
158 ep = tmp + sizeof(tmp);
159 for (i = 0; i < (IN6ADDRSZ / INT16SZ) && tp < ep; i++) {
160 /* Are we inside the best run of 0x00's? */
161 if (best.base != -1 && i >= best.base &&
162 i < (best.base + best.len)) {
163 if (i == best.base) {
164 if (tp + 1 >= ep)
165 return (NULL);
166 *tp++ = ':';
167 }
168 continue;
169 }
170 /* Are we following an initial run of 0x00s or any real hex? */
171 if (i != 0) {
172 if (tp + 1 >= ep)
173 return (NULL);
174 *tp++ = ':';
175 }
176 /* Is this address an encapsulated IPv4? */
177 if (i == 6 && best.base == 0 &&
178 (best.len == 6 || (best.len == 5 && words[5] == 0xffff))) {
179 if (!inet_ntop4(src+12, tp, (size_t)(ep - tp)))
180 return (NULL);
181 tp += strlen(tp);
182 break;
183 }
184 advance = snprintf(tp, ep - tp, "%x", words[i]);
185 if (advance <= 0 || advance >= ep - tp)
186 return (NULL);
187 tp += advance;
188 }
189 /* Was it a trailing run of 0x00's? */
190 if (best.base != -1 && (best.base + best.len) == (IN6ADDRSZ / INT16SZ)) {
191 if (tp + 1 >= ep)
192 return (NULL);
193 *tp++ = ':';
194 }
195 if (tp + 1 >= ep)
196 return (NULL);
197 *tp++ = '\0';
198
199 /*
200 * Check for overflow, copy, and we're done.
201 */
202 if ((size_t)(tp - tmp) > size) {
203 errno = ENOSPC;
204 return (NULL);
205 }
206 strlcpy(dst, tmp, size);
207 return (dst);
208 }
209
210 #endif /* !HAVE_INET_NTOP */
211