1 /* Copyright (c) 1996 by Internet Software Consortium.
2 *
3 * Permission to use, copy, modify, and distribute this software for any
4 * purpose with or without fee is hereby granted, provided that the above
5 * copyright notice and this permission notice appear in all copies.
6 *
7 * THE SOFTWARE IS PROVIDED "AS IS" AND INTERNET SOFTWARE CONSORTIUM DISCLAIMS
8 * ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES
9 * OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL INTERNET SOFTWARE
10 * CONSORTIUM BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
11 * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
12 * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
13 * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
14 * SOFTWARE.
15 */
16
17 #if defined(LIBC_SCCS) && !defined(lint)
18 static char rcsid[] = "$Id: inet_ntop.c 135 2004-10-08 10:01:07Z oyvind $";
19 #endif /* LIBC_SCCS and not lint */
20 #include <sys/cdefs.h>
21 #include <sys/types.h>
22
23 #include <sys/param.h>
24 #include <sys/types.h>
25 #include <sys/socket.h>
26 #include <netinet/in.h>
27 #include <arpa/inet.h>
28 #include <arpa/nameser.h>
29 #include <errno.h>
30 #include <stdio.h>
31 #include <string.h>
32
33 #define SPRINTF(x) ((socklen_t)sprintf x)
34
35 /*
36 * WARNING: Don't even consider trying to compile this on a system where
37 * sizeof(int) < 4. sizeof(int) > 4 is fine; all the world's not a VAX.
38 */
39
40 static const char *inet_ntop4(const u_char *src, char *dst, socklen_t size);
41 static const char *inet_ntop6(const u_char *src, char *dst, socklen_t size);
42
43 /* char *
44 * inet_ntop(af, src, dst, size)
45 * convert a network format address to presentation format.
46 * return:
47 * pointer to presentation format address (`dst'), or NULL (see errno).
48 * author:
49 * Paul Vixie, 1996.
50 */
51 const char *
inet_ntop(af,src,dst,size)52 inet_ntop(af, src, dst, size)
53 int af;
54 const void *src;
55 char *dst;
56 socklen_t size;
57 {
58 switch (af) {
59 case AF_INET:
60 return (inet_ntop4(src, dst, size));
61 case AF_INET6:
62 return (inet_ntop6(src, dst, size));
63 default:
64 errno = EAFNOSUPPORT;
65 return (NULL);
66 }
67 /* NOTREACHED */
68 }
69
70 /* const char *
71 * inet_ntop4(src, dst, size)
72 * format an IPv4 address, more or less like inet_ntoa()
73 * return:
74 * `dst' (as a const)
75 * notes:
76 * (1) uses no statics
77 * (2) takes a u_char* not an in_addr as input
78 * author:
79 * Paul Vixie, 1996.
80 */
81 static const char *
inet_ntop4(src,dst,size)82 inet_ntop4(src, dst, size)
83 const u_char *src;
84 char *dst;
85 socklen_t size;
86 {
87 static const char fmt[] = "%u.%u.%u.%u";
88 char tmp[sizeof "255.255.255.255"];
89
90 if (SPRINTF((tmp, fmt, src[0], src[1], src[2], src[3])) > size) {
91 errno = ENOSPC;
92 return (NULL);
93 }
94 strcpy(dst, tmp);
95 return (dst);
96 }
97
98 /* const char *
99 * inet_ntop6(src, dst, size)
100 * convert IPv6 binary address into presentation (printable) format
101 * author:
102 * Paul Vixie, 1996.
103 */
104 static const char *
inet_ntop6(src,dst,size)105 inet_ntop6(src, dst, size)
106 const u_char *src;
107 char *dst;
108 socklen_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"], *tp;
118 struct { int base, len; } best, cur;
119 u_int words[NS_IN6ADDRSZ / NS_INT16SZ];
120 int i;
121
122 /*
123 * Preprocess:
124 * Copy the input (bytewise) array into a wordwise array.
125 * Find the longest run of 0x00's in src[] for :: shorthanding.
126 */
127 memset(words, '\0', sizeof words);
128 for (i = 0; i < NS_IN6ADDRSZ; i++)
129 words[i / 2] |= (src[i] << ((1 - (i % 2)) << 3));
130 best.base = -1;
131 cur.base = -1;
132 for (i = 0; i < (NS_IN6ADDRSZ / NS_INT16SZ); i++) {
133 if (words[i] == 0) {
134 if (cur.base == -1)
135 cur.base = i, cur.len = 1;
136 else
137 cur.len++;
138 } else {
139 if (cur.base != -1) {
140 if (best.base == -1 || cur.len > best.len)
141 best = cur;
142 cur.base = -1;
143 }
144 }
145 }
146 if (cur.base != -1) {
147 if (best.base == -1 || cur.len > best.len)
148 best = cur;
149 }
150 if (best.base != -1 && best.len < 2)
151 best.base = -1;
152
153 /*
154 * Format the result.
155 */
156 tp = tmp;
157 for (i = 0; i < (NS_IN6ADDRSZ / NS_INT16SZ); i++) {
158 /* Are we inside the best run of 0x00's? */
159 if (best.base != -1 && i >= best.base &&
160 i < (best.base + best.len)) {
161 if (i == best.base)
162 *tp++ = ':';
163 continue;
164 }
165 /* Are we following an initial run of 0x00s or any real hex? */
166 if (i != 0)
167 *tp++ = ':';
168 /* Is this address an encapsulated IPv4? */
169 if (i == 6 && best.base == 0 &&
170 (best.len == 6 || (best.len == 5 && words[5] == 0xffff))) {
171 if (!inet_ntop4(src+12, tp, sizeof tmp - (tp - tmp)))
172 return (NULL);
173 tp += strlen(tp);
174 break;
175 }
176 tp += SPRINTF((tp, "%x", words[i]));
177 }
178 /* Was it a trailing run of 0x00's? */
179 if (best.base != -1 && (best.base + best.len) ==
180 (NS_IN6ADDRSZ / NS_INT16SZ))
181 *tp++ = ':';
182 *tp++ = '\0';
183
184 /*
185 * Check for overflow, copy, and we're done.
186 */
187 if ((socklen_t)(tp - tmp) > size) {
188 errno = ENOSPC;
189 return (NULL);
190 }
191 strcpy(dst, tmp);
192 return (dst);
193 }
194
195 /*
196 * Weak aliases for applications that use certain private entry points,
197 * and fail to include <arpa/inet.h>.
198 */
199 #undef inet_ntop
200 __weak_reference(__inet_ntop, inet_ntop);
201