1 | /* $OpenBSD: inet_ntop.c,v 1.1 1997/03/13 19:07:32 downsj 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 | #define __P(a) a
19 |
20 | #if defined(LIBC_SCCS) && !defined(lint)
21 | #if 0
22 | static char rcsid[] = "$From: inet_ntop.c,v 8.7 1996/08/05 08:41:18 vixie Exp $";
23 | #else
24 | static char rcsid[] = "$OpenBSD: inet_ntop.c,v 1.1 1997/03/13 19:07:32 downsj Exp $";
25 | #endif
26 | #endif /* LIBC_SCCS and not lint */
27 |
28 | #include <sys/param.h>
29 | #include <sys/types.h>
30 | #include <sys/socket.h>
31 | #include <netinet/in.h>
32 | #include <arpa/inet.h>
33 | #include <arpa/nameser.h>
34 |
35 | #include <string.h>
36 | #include <errno.h>
37 | #include <stdio.h>
38 |
39 | #include "inet6def.h"
40 |
41 | /*
42 | * WARNING: Don't even consider trying to compile this on a system where
43 | * sizeof(int) < 4. sizeof(int) > 4 is fine; all the world's not a VAX.
44 | */
45 |
46 | static const char *inet_ntop4 __P((const u_char *src, char *dst, size_t size));
47 | static const char *inet_ntop6 __P((const u_char *src, char *dst, size_t size));
48 |
49 | /* char *
50 | * inet_ntop(af, src, dst, size)
51 | * convert a network format address to presentation format.
52 | * return:
53 | * pointer to presentation format address (`dst'), or NULL (see errno).
54 | * author:
55 | * Paul Vixie, 1996.
56 | */
57 | const char *
58 | inet_ntop(af, src, dst, size)
59 | int af;
60 | const void *src;
61 | char *dst;
62 | size_t size;
63 | {
64 | switch (af) {
65 | case AF_INET:
66 | return (inet_ntop4(src, dst, size));
67 | case AF_INET6:
68 | return (inet_ntop6(src, dst, size));
69 | default:
70 | errno = EAFNOSUPPORT;
71 | return (NULL);
72 | }
73 | /* NOTREACHED */
74 | }
75 |
76 | /* const char *
77 | * inet_ntop4(src, dst, size)
78 | * format an IPv4 address, more or less like inet_ntoa()
79 | * return:
80 | * `dst' (as a const)
81 | * notes:
82 | * (1) uses no statics
83 | * (2) takes a u_char* not an in_addr as input
84 | * author:
85 | * Paul Vixie, 1996.
86 | */
87 | static const char *
88 | inet_ntop4(src, dst, size)
89 | const u_char *src;
90 | char *dst;
91 | size_t size;
92 | {
93 | static const char fmt[] = "%u.%u.%u.%u";
94 | char tmp[sizeof "255.255.255.255"];
95 |
96 | if (sprintf(tmp, fmt, src[0], src[1], src[2], src[3]) > size) {
97 | errno = ENOSPC;
98 | return (NULL);
99 | }
100 | strcpy(dst, tmp);
101 | return (dst);
102 | }
103 |
104 | /* const char *
105 | * inet_ntop6(src, dst, size)
106 | * convert IPv6 binary address into presentation (printable) format
107 | * author:
108 | * Paul Vixie, 1996.
109 | */
110 | static const char *
111 | inet_ntop6(src, dst, size)
112 | const u_char *src;
113 | char *dst;
114 | size_t size;
115 | {
116 | /*
117 | * Note that int32_t and int16_t need only be "at least" large enough
118 | * to contain a value of the specified size. On some systems, like
119 | * Crays, there is no such thing as an integer variable with 16 bits.
120 | * Keep this in mind if you think this function should have been coded
121 | * to use pointer overlays. All the world's not a VAX.
122 | */
123 | char tmp[sizeof "ffff:ffff:ffff:ffff:ffff:ffff:255.255.255.255"], *tp;
124 | struct { int base, len; } best, cur;
125 | u_int words[IN6ADDRSZ / INT16SZ];
126 | int i;
127 |
128 | /*
129 | * Preprocess:
130 | * Copy the input (bytewise) array into a wordwise array.
131 | * Find the longest run of 0x00's in src[] for :: shorthanding.
132 | */
133 | memset(words, '\0', sizeof words);
134 | for (i = 0; i < IN6ADDRSZ; i++)
135 | words[i / 2] |= (src[i] << ((1 - (i % 2)) << 3));
136 | best.base = -1;
137 | cur.base = -1;
138 | for (i = 0; i < (IN6ADDRSZ / INT16SZ); i++) {
139 | if (words[i] == 0) {
140 | if (cur.base == -1)
141 | cur.base = i, cur.len = 1;
142 | else
143 | cur.len++;
144 | } else {
145 | if (cur.base != -1) {
146 | if (best.base == -1 || cur.len > best.len)
147 | best = cur;
148 | cur.base = -1;
149 | }
150 | }
151 | }
152 | if (cur.base != -1) {
153 | if (best.base == -1 || cur.len > best.len)
154 | best = cur;
155 | }
156 | if (best.base != -1 && best.len < 2)
157 | best.base = -1;
158 |
159 | /*
160 | * Format the result.
161 | */
162 | tp = tmp;
163 | for (i = 0; i < (IN6ADDRSZ / INT16SZ); i++) {
164 | /* Are we inside the best run of 0x00's? */
165 | if (best.base != -1 && i >= best.base &&
166 | i < (best.base + best.len)) {
167 | if (i == best.base)
168 | *tp++ = ':';
169 | continue;
170 | }
171 | /* Are we following an initial run of 0x00s or any real hex? */
172 | if (i != 0)
173 | *tp++ = ':';
174 | /* Is this address an encapsulated IPv4? */
175 | if (i == 6 && best.base == 0 &&
176 | (best.len == 6 || (best.len == 5 && words[5] == 0xffff))) {
177 | if (!inet_ntop4(src+12, tp, sizeof tmp - (tp - tmp)))
178 | return (NULL);
179 | tp += strlen(tp);
180 | break;
181 | }
182 | tp += sprintf(tp, "%x", words[i]);
183 | }
184 | /* Was it a trailing run of 0x00's? */
185 | if (best.base != -1 && (best.base + best.len) == (IN6ADDRSZ / INT16SZ))
186 | *tp++ = ':';
187 | *tp++ = '\0';
188 |
189 | /*
190 | * Check for overflow, copy, and we're done.
191 | */
192 | if ((size_t)(tp - tmp) > size) {
193 | errno = ENOSPC;
194 | return (NULL);
195 | }
196 | strcpy(dst, tmp);
197 | return (dst);
198 | }