Update.
[glibc.git] / resolv / inet_ntop.c
blobf99a69ba7550fadc3b97d17ba0a3391e3bb7f5fa
1 /*
2 * Copyright (c) 1996-1999 by Internet Software Consortium.
4 * Permission to use, copy, modify, and distribute this software for any
5 * purpose with or without fee is hereby granted, provided that the above
6 * copyright notice and this permission notice appear in all copies.
8 * THE SOFTWARE IS PROVIDED "AS IS" AND INTERNET SOFTWARE CONSORTIUM DISCLAIMS
9 * ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES
10 * OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL INTERNET SOFTWARE
11 * CONSORTIUM BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
12 * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
13 * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
14 * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
15 * SOFTWARE.
18 #if defined(LIBC_SCCS) && !defined(lint)
19 static const char rcsid[] = "$BINDId: inet_ntop.c,v 1.8 1999/10/13 16:39:28 vixie Exp $";
20 #endif /* LIBC_SCCS and not lint */
22 #include <sys/param.h>
23 #include <sys/types.h>
24 #include <sys/socket.h>
26 #include <netinet/in.h>
27 #include <arpa/inet.h>
28 #include <arpa/nameser.h>
30 #include <errno.h>
31 #include <stdio.h>
32 #include <string.h>
34 #ifdef SPRINTF_CHAR
35 # define SPRINTF(x) strlen(sprintf/**/x)
36 #else
37 # define SPRINTF(x) ((size_t)sprintf x)
38 #endif
41 * WARNING: Don't even consider trying to compile this on a system where
42 * sizeof(int) < 4. sizeof(int) > 4 is fine; all the world's not a VAX.
45 static const char *inet_ntop4 (const u_char *src, char *dst, socklen_t size)
46 internal_function;
47 static const char *inet_ntop6 (const u_char *src, char *dst, socklen_t size)
48 internal_function;
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.
58 const char *
59 inet_ntop(af, src, dst, size)
60 int af;
61 const void *src;
62 char *dst;
63 socklen_t size;
65 switch (af) {
66 case AF_INET:
67 return (inet_ntop4(src, dst, size));
68 case AF_INET6:
69 return (inet_ntop6(src, dst, size));
70 default:
71 __set_errno (EAFNOSUPPORT);
72 return (NULL);
74 /* NOTREACHED */
77 /* const char *
78 * inet_ntop4(src, dst, size)
79 * format an IPv4 address
80 * return:
81 * `dst' (as a const)
82 * notes:
83 * (1) uses no statics
84 * (2) takes a u_char* not an in_addr as input
85 * author:
86 * Paul Vixie, 1996.
88 static const char *
89 internal_function
90 inet_ntop4(src, dst, size)
91 const u_char *src;
92 char *dst;
93 socklen_t size;
95 static const char fmt[] = "%u.%u.%u.%u";
96 char tmp[sizeof "255.255.255.255"];
98 if (SPRINTF((tmp, fmt, src[0], src[1], src[2], src[3])) > size) {
99 __set_errno (ENOSPC);
100 return (NULL);
102 return strcpy(dst, tmp);
105 /* const char *
106 * inet_ntop6(src, dst, size)
107 * convert IPv6 binary address into presentation (printable) format
108 * author:
109 * Paul Vixie, 1996.
111 static const char *
112 internal_function
113 inet_ntop6(src, dst, size)
114 const u_char *src;
115 char *dst;
116 socklen_t size;
119 * Note that int32_t and int16_t need only be "at least" large enough
120 * to contain a value of the specified size. On some systems, like
121 * Crays, there is no such thing as an integer variable with 16 bits.
122 * Keep this in mind if you think this function should have been coded
123 * to use pointer overlays. All the world's not a VAX.
125 char tmp[sizeof "ffff:ffff:ffff:ffff:ffff:ffff:255.255.255.255"], *tp;
126 struct { int base, len; } best, cur;
127 u_int words[NS_IN6ADDRSZ / NS_INT16SZ];
128 int i;
131 * Preprocess:
132 * Copy the input (bytewise) array into a wordwise array.
133 * Find the longest run of 0x00's in src[] for :: shorthanding.
135 memset(words, '\0', sizeof words);
136 for (i = 0; i < NS_IN6ADDRSZ; i += 2)
137 words[i / 2] = (src[i] << 8) | src[i + 1];
138 best.base = -1;
139 cur.base = -1;
140 for (i = 0; i < (NS_IN6ADDRSZ / NS_INT16SZ); i++) {
141 if (words[i] == 0) {
142 if (cur.base == -1)
143 cur.base = i, cur.len = 1;
144 else
145 cur.len++;
146 } else {
147 if (cur.base != -1) {
148 if (best.base == -1 || cur.len > best.len)
149 best = cur;
150 cur.base = -1;
154 if (cur.base != -1) {
155 if (best.base == -1 || cur.len > best.len)
156 best = cur;
158 if (best.base != -1 && best.len < 2)
159 best.base = -1;
162 * Format the result.
164 tp = tmp;
165 for (i = 0; i < (NS_IN6ADDRSZ / NS_INT16SZ); i++) {
166 /* Are we inside the best run of 0x00's? */
167 if (best.base != -1 && i >= best.base &&
168 i < (best.base + best.len)) {
169 if (i == best.base)
170 *tp++ = ':';
171 continue;
173 /* Are we following an initial run of 0x00s or any real hex? */
174 if (i != 0)
175 *tp++ = ':';
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, sizeof tmp - (tp - tmp)))
180 return (NULL);
181 tp += strlen(tp);
182 break;
184 tp += SPRINTF((tp, "%x", words[i]));
186 /* Was it a trailing run of 0x00's? */
187 if (best.base != -1 && (best.base + best.len) ==
188 (NS_IN6ADDRSZ / NS_INT16SZ))
189 *tp++ = ':';
190 *tp++ = '\0';
193 * Check for overflow, copy, and we're done.
195 if ((socklen_t)(tp - tmp) > size) {
196 __set_errno (ENOSPC);
197 return (NULL);
199 return strcpy(dst, tmp);