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 #include <sys/param.h>
19 #include <sys/types.h>
20 #include <sys/socket.h>
21
22 #include <netinet/in.h>
23 #include <arpa/inet.h>
24 #include <arpa/nameser.h>
25
26 #include <errno.h>
27 #include <stdio.h>
28 #include <string.h>
29
30 #ifdef SPRINTF_CHAR
31 # define SPRINTF(x) strlen(sprintf/**/x)
32 #else
33 # define SPRINTF(x) ((size_t)sprintf x)
34 #endif
35
36 /*
37 * WARNING: Don't even consider trying to compile this on a system where
38 * sizeof(int) < 4. sizeof(int) > 4 is fine; all the world's not a VAX.
39 */
40
41 static const char *inet_ntop4 (const u_char *src, char *dst, socklen_t size);
42 static const char *inet_ntop6 (const u_char *src, char *dst, socklen_t size);
43
44 /* char *
45 * inet_ntop(af, src, dst, size)
46 * convert a network format address to presentation format.
47 * return:
48 * pointer to presentation format address (`dst'), or NULL (see errno).
49 * author:
50 * Paul Vixie, 1996.
51 */
52 const char *
53 inet_ntop (int af, const void *src, char *dst, socklen_t size)
54 {
55 switch (af) {
56 case AF_INET:
57 return (inet_ntop4(src, dst, size));
58 case AF_INET6:
59 return (inet_ntop6(src, dst, size));
60 default:
61 __set_errno (EAFNOSUPPORT);
62 return (NULL);
63 }
64 /* NOTREACHED */
65 }
66 libc_hidden_def (inet_ntop)
67
68 /* const char *
69 * inet_ntop4(src, dst, size)
70 * format an IPv4 address
71 * return:
72 * `dst' (as a const)
73 * notes:
74 * (1) uses no statics
75 * (2) takes a u_char* not an in_addr as input
76 * author:
77 * Paul Vixie, 1996.
78 */
79 static const char *
80 inet_ntop4 (const u_char *src, char *dst, socklen_t size)
81 {
82 static const char fmt[] = "%u.%u.%u.%u";
83 char tmp[sizeof "255.255.255.255"];
84
85 if (SPRINTF((tmp, fmt, src[0], src[1], src[2], src[3])) >= size) {
86 __set_errno (ENOSPC);
87 return (NULL);
88 }
89 return strcpy(dst, tmp);
90 }
91
92 /* const char *
93 * inet_ntop6(src, dst, size)
94 * convert IPv6 binary address into presentation (printable) format
95 * author:
96 * Paul Vixie, 1996.
97 */
98 static const char *
99 inet_ntop6 (const u_char *src, char *dst, socklen_t size)
100 {
101 /*
102 * Note that int32_t and int16_t need only be "at least" large enough
103 * to contain a value of the specified size. On some systems, like
104 * Crays, there is no such thing as an integer variable with 16 bits.
105 * Keep this in mind if you think this function should have been coded
106 * to use pointer overlays. All the world's not a VAX.
107 */
108 char tmp[sizeof "ffff:ffff:ffff:ffff:ffff:ffff:255.255.255.255"], *tp;
109 struct { int base, len; } best, cur;
110 u_int words[NS_IN6ADDRSZ / NS_INT16SZ];
111 int i;
112
113 /*
114 * Preprocess:
115 * Copy the input (bytewise) array into a wordwise array.
116 * Find the longest run of 0x00's in src[] for :: shorthanding.
117 */
118 memset(words, '\0', sizeof words);
119 for (i = 0; i < NS_IN6ADDRSZ; i += 2)
120 words[i / 2] = (src[i] << 8) | src[i + 1];
121 best.base = -1;
122 cur.base = -1;
123 best.len = 0;
124 cur.len = 0;
125 for (i = 0; i < (NS_IN6ADDRSZ / NS_INT16SZ); i++) {
126 if (words[i] == 0) {
127 if (cur.base == -1)
128 cur.base = i, cur.len = 1;
129 else
130 cur.len++;
131 } else {
132 if (cur.base != -1) {
133 if (best.base == -1 || cur.len > best.len)
134 best = cur;
135 cur.base = -1;
136 }
137 }
138 }
139 if (cur.base != -1) {
140 if (best.base == -1 || cur.len > best.len)
141 best = cur;
142 }
143 if (best.base != -1 && best.len < 2)
144 best.base = -1;
145
146 /*
147 * Format the result.
148 */
149 tp = tmp;
150 for (i = 0; i < (NS_IN6ADDRSZ / NS_INT16SZ); i++) {
151 /* Are we inside the best run of 0x00's? */
152 if (best.base != -1 && i >= best.base &&
153 i < (best.base + best.len)) {
154 if (i == best.base)
155 *tp++ = ':';
156 continue;
157 }
158 /* Are we following an initial run of 0x00s or any real hex? */
159 if (i != 0)
160 *tp++ = ':';
161 /* Is this address an encapsulated IPv4? */
162 if (i == 6 && best.base == 0 &&
163 (best.len == 6 || (best.len == 5 && words[5] == 0xffff))) {
164 if (!inet_ntop4(src+12, tp, sizeof tmp - (tp - tmp)))
165 return (NULL);
166 tp += strlen(tp);
167 break;
168 }
169 tp += SPRINTF((tp, "%x", words[i]));
170 }
171 /* Was it a trailing run of 0x00's? */
172 if (best.base != -1 && (best.base + best.len) ==
173 (NS_IN6ADDRSZ / NS_INT16SZ))
174 *tp++ = ':';
175 *tp++ = '\0';
176
177 /*
178 * Check for overflow, copy, and we're done.
179 */
180 if ((socklen_t)(tp - tmp) > size) {
181 __set_errno (ENOSPC);
182 return (NULL);
183 }
184 return strcpy(dst, tmp);
185 }