1/*
2 * Copyright (c) 1996-1999 by Internet Software Consortium.
3 *
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.
7 *
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.
16 */
17
18#if defined(LIBC_SCCS) && !defined(lint)
19static 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 */
21
22#include <sys/param.h>
23#include <sys/types.h>
24#include <sys/socket.h>
25
26#include <netinet/in.h>
27#include <arpa/inet.h>
28#include <arpa/nameser.h>
29
30#include <errno.h>
31#include <stdio.h>
32#include <string.h>
33
34#ifdef SPRINTF_CHAR
35# define SPRINTF(x) strlen(sprintf/**/x)
36#else
37# define SPRINTF(x) ((size_t)sprintf x)
38#endif
39
40/*
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.
43 */
44
45static const char *inet_ntop4 (const u_char *src, char *dst, socklen_t size)
46 internal_function;
47static const char *inet_ntop6 (const u_char *src, char *dst, socklen_t size)
48 internal_function;
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 */
58const char *
59inet_ntop(af, src, dst, size)
60 int af;
61 const void *src;
62 char *dst;
63 socklen_t size;
64{
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);
73 }
74 /* NOTREACHED */
75}
76libc_hidden_def (inet_ntop)
77
78/* const char *
79 * inet_ntop4(src, dst, size)
80 * format an IPv4 address
81 * return:
82 * `dst' (as a const)
83 * notes:
84 * (1) uses no statics
85 * (2) takes a u_char* not an in_addr as input
86 * author:
87 * Paul Vixie, 1996.
88 */
89static const char *
90internal_function
91inet_ntop4(src, dst, size)
92 const u_char *src;
93 char *dst;
94 socklen_t size;
95{
96 static const char fmt[] = "%u.%u.%u.%u";
97 char tmp[sizeof "255.255.255.255"];
98
99 if (SPRINTF((tmp, fmt, src[0], src[1], src[2], src[3])) >= size) {
100 __set_errno (ENOSPC);
101 return (NULL);
102 }
103 return strcpy(dst, tmp);
104}
105
106/* const char *
107 * inet_ntop6(src, dst, size)
108 * convert IPv6 binary address into presentation (printable) format
109 * author:
110 * Paul Vixie, 1996.
111 */
112static const char *
113internal_function
114inet_ntop6(src, dst, size)
115 const u_char *src;
116 char *dst;
117 socklen_t size;
118{
119 /*
120 * Note that int32_t and int16_t need only be "at least" large enough
121 * to contain a value of the specified size. On some systems, like
122 * Crays, there is no such thing as an integer variable with 16 bits.
123 * Keep this in mind if you think this function should have been coded
124 * to use pointer overlays. All the world's not a VAX.
125 */
126 char tmp[sizeof "ffff:ffff:ffff:ffff:ffff:ffff:255.255.255.255"], *tp;
127 struct { int base, len; } best, cur;
128 u_int words[NS_IN6ADDRSZ / NS_INT16SZ];
129 int i;
130
131 /*
132 * Preprocess:
133 * Copy the input (bytewise) array into a wordwise array.
134 * Find the longest run of 0x00's in src[] for :: shorthanding.
135 */
136 memset(words, '\0', sizeof words);
137 for (i = 0; i < NS_IN6ADDRSZ; i += 2)
138 words[i / 2] = (src[i] << 8) | src[i + 1];
139 best.base = -1;
140 cur.base = -1;
141 best.len = 0;
142 cur.len = 0;
143 for (i = 0; i < (NS_IN6ADDRSZ / NS_INT16SZ); i++) {
144 if (words[i] == 0) {
145 if (cur.base == -1)
146 cur.base = i, cur.len = 1;
147 else
148 cur.len++;
149 } else {
150 if (cur.base != -1) {
151 if (best.base == -1 || cur.len > best.len)
152 best = cur;
153 cur.base = -1;
154 }
155 }
156 }
157 if (cur.base != -1) {
158 if (best.base == -1 || cur.len > best.len)
159 best = cur;
160 }
161 if (best.base != -1 && best.len < 2)
162 best.base = -1;
163
164 /*
165 * Format the result.
166 */
167 tp = tmp;
168 for (i = 0; i < (NS_IN6ADDRSZ / NS_INT16SZ); i++) {
169 /* Are we inside the best run of 0x00's? */
170 if (best.base != -1 && i >= best.base &&
171 i < (best.base + best.len)) {
172 if (i == best.base)
173 *tp++ = ':';
174 continue;
175 }
176 /* Are we following an initial run of 0x00s or any real hex? */
177 if (i != 0)
178 *tp++ = ':';
179 /* Is this address an encapsulated IPv4? */
180 if (i == 6 && best.base == 0 &&
181 (best.len == 6 || (best.len == 5 && words[5] == 0xffff))) {
182 if (!inet_ntop4(src+12, tp, sizeof tmp - (tp - tmp)))
183 return (NULL);
184 tp += strlen(tp);
185 break;
186 }
187 tp += SPRINTF((tp, "%x", words[i]));
188 }
189 /* Was it a trailing run of 0x00's? */
190 if (best.base != -1 && (best.base + best.len) ==
191 (NS_IN6ADDRSZ / NS_INT16SZ))
192 *tp++ = ':';
193 *tp++ = '\0';
194
195 /*
196 * Check for overflow, copy, and we're done.
197 */
198 if ((socklen_t)(tp - tmp) > size) {
199 __set_errno (ENOSPC);
200 return (NULL);
201 }
202 return strcpy(dst, tmp);
203}
204