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/param.h>
26 #include <sys/types.h>
27 #include <sys/socket.h>
28 #include <netinet/in.h>
29 #include <arpa/inet.h>
30 #include <arpa/nameser.h>
31 #include <string.h>
32 #include <errno.h>
33 #include <stdio.h>
34
35 #ifndef IN6ADDRSZ
36 #define IN6ADDRSZ 16 /* IPv6 T_AAAA */
37 #endif
38
39 #ifndef INT16SZ
40 #define INT16SZ 2 /* for systems without 16-bit ints */
41 #endif
42
43 /*
44 * WARNING: Don't even consider trying to compile this on a system where
45 * sizeof(int) < 4. sizeof(int) > 4 is fine; all the world's not a VAX.
46 */
47
48 static const char *inet_ntop4(const u_char *src, char *dst, size_t size);
49 static const char *inet_ntop6(const u_char *src, char *dst, size_t size);
50
51 /* char *
52 * inet_ntop(af, src, dst, size)
53 * convert a network format address to presentation format.
54 * return:
55 * pointer to presentation format address (`dst'), or NULL (see errno).
56 * author:
57 * Paul Vixie, 1996.
58 */
59 const char *
inet_ntop(int af,const void * src,char * dst,socklen_t size)60 inet_ntop(int af, const void *src, char *dst, socklen_t size)
61 {
62 switch (af) {
63 case AF_INET:
64 return (inet_ntop4(src, dst, (size_t)size));
65 case AF_INET6:
66 return (inet_ntop6(src, dst, (size_t)size));
67 default:
68 errno = EAFNOSUPPORT;
69 return (NULL);
70 }
71 /* NOTREACHED */
72 }
73
74 /* const char *
75 * inet_ntop4(src, dst, size)
76 * format an IPv4 address, more or less like inet_ntoa()
77 * return:
78 * `dst' (as a const)
79 * notes:
80 * (1) uses no statics
81 * (2) takes a u_char* not an in_addr as input
82 * author:
83 * Paul Vixie, 1996.
84 */
85 static const char *
inet_ntop4(const u_char * src,char * dst,size_t size)86 inet_ntop4(const u_char *src, char *dst, size_t size)
87 {
88 static const char fmt[] = "%u.%u.%u.%u";
89 char tmp[sizeof "255.255.255.255"];
90 int l;
91
92 l = snprintf(tmp, size, fmt, src[0], src[1], src[2], src[3]);
93 if (l <= 0 || l >= size) {
94 errno = ENOSPC;
95 return (NULL);
96 }
97 strlcpy(dst, tmp, size);
98 return (dst);
99 }
100
101 /* const char *
102 * inet_ntop6(src, dst, size)
103 * convert IPv6 binary address into presentation (printable) format
104 * author:
105 * Paul Vixie, 1996.
106 */
107 static const char *
inet_ntop6(const u_char * src,char * dst,size_t size)108 inet_ntop6(const u_char *src, char *dst, size_t size)
109 {
110 /*
111 * Note that int32_t and int16_t need only be "at least" large enough
112 * to contain a value of the specified size. On some systems, like
113 * Crays, there is no such thing as an integer variable with 16 bits.
114 * Keep this in mind if you think this function should have been coded
115 * to use pointer overlays. All the world's not a VAX.
116 */
117 char tmp[sizeof "ffff:ffff:ffff:ffff:ffff:ffff:255.255.255.255"];
118 char *tp, *ep;
119 struct { int base, len; } best, cur;
120 u_int words[IN6ADDRSZ / INT16SZ];
121 int i;
122 int advance;
123
124 /*
125 * Preprocess:
126 * Copy the input (bytewise) array into a wordwise array.
127 * Find the longest run of 0x00's in src[] for :: shorthanding.
128 */
129 memset(words, '\0', sizeof words);
130 for (i = 0; i < IN6ADDRSZ; i++)
131 words[i / 2] |= (src[i] << ((1 - (i % 2)) << 3));
132 best.base = -1;
133 cur.base = -1;
134 for (i = 0; i < (IN6ADDRSZ / INT16SZ); i++) {
135 if (words[i] == 0) {
136 if (cur.base == -1)
137 cur.base = i, cur.len = 1;
138 else
139 cur.len++;
140 } else {
141 if (cur.base != -1) {
142 if (best.base == -1 || cur.len > best.len)
143 best = cur;
144 cur.base = -1;
145 }
146 }
147 }
148 if (cur.base != -1) {
149 if (best.base == -1 || cur.len > best.len)
150 best = cur;
151 }
152 if (best.base != -1 && best.len < 2)
153 best.base = -1;
154
155 /*
156 * Format the result.
157 */
158 tp = tmp;
159 ep = tmp + sizeof(tmp);
160 for (i = 0; i < (IN6ADDRSZ / INT16SZ) && tp < ep; i++) {
161 /* Are we inside the best run of 0x00's? */
162 if (best.base != -1 && i >= best.base &&
163 i < (best.base + best.len)) {
164 if (i == best.base) {
165 if (tp + 1 >= ep)
166 return (NULL);
167 *tp++ = ':';
168 }
169 continue;
170 }
171 /* Are we following an initial run of 0x00s or any real hex? */
172 if (i != 0) {
173 if (tp + 1 >= ep)
174 return (NULL);
175 *tp++ = ':';
176 }
177 /* Is this address an encapsulated IPv4? */
178 if (i == 6 && best.base == 0 &&
179 (best.len == 6 || (best.len == 5 && words[5] == 0xffff))) {
180 if (!inet_ntop4(src+12, tp, (size_t)(ep - tp)))
181 return (NULL);
182 tp += strlen(tp);
183 break;
184 }
185 advance = snprintf(tp, ep - tp, "%x", words[i]);
186 if (advance <= 0 || advance >= ep - tp)
187 return (NULL);
188 tp += advance;
189 }
190 /* Was it a trailing run of 0x00's? */
191 if (best.base != -1 && (best.base + best.len) == (IN6ADDRSZ / INT16SZ)) {
192 if (tp + 1 >= ep)
193 return (NULL);
194 *tp++ = ':';
195 }
196 if (tp + 1 >= ep)
197 return (NULL);
198 *tp++ = '\0';
199
200 /*
201 * Check for overflow, copy, and we're done.
202 */
203 if ((size_t)(tp - tmp) > size) {
204 errno = ENOSPC;
205 return (NULL);
206 }
207 strlcpy(dst, tmp, size);
208 return (dst);
209 }
210
211 #endif /* !HAVE_INET_NTOP */
212