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
41static const char *inet_ntop4 (const u_char *src, char *dst, socklen_t size)
42 internal_function;
43static const char *inet_ntop6 (const u_char *src, char *dst, socklen_t size)
44 internal_function;
45
46/* char *
47 * inet_ntop(af, src, dst, size)
48 * convert a network format address to presentation format.
49 * return:
50 * pointer to presentation format address (`dst'), or NULL (see errno).
51 * author:
52 * Paul Vixie, 1996.
53 */
54const char *
55inet_ntop (int af, const void *src, char *dst, socklen_t size)
56{
57 switch (af) {
58 case AF_INET:
59 return (inet_ntop4(src, dst, size));
60 case AF_INET6:
61 return (inet_ntop6(src, dst, size));
62 default:
63 __set_errno (EAFNOSUPPORT);
64 return (NULL);
65 }
66 /* NOTREACHED */
67}
68libc_hidden_def (inet_ntop)
69
70/* const char *
71 * inet_ntop4(src, dst, size)
72 * format an IPv4 address
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 */
81static const char *
82internal_function
83inet_ntop4 (const u_char *src, char *dst, socklen_t size)
84{
85 static const char fmt[] = "%u.%u.%u.%u";
86 char tmp[sizeof "255.255.255.255"];
87
88 if (SPRINTF((tmp, fmt, src[0], src[1], src[2], src[3])) >= size) {
89 __set_errno (ENOSPC);
90 return (NULL);
91 }
92 return strcpy(dst, tmp);
93}
94
95/* const char *
96 * inet_ntop6(src, dst, size)
97 * convert IPv6 binary address into presentation (printable) format
98 * author:
99 * Paul Vixie, 1996.
100 */
101static const char *
102internal_function
103inet_ntop6 (const u_char *src, char *dst, socklen_t size)
104{
105 /*
106 * Note that int32_t and int16_t need only be "at least" large enough
107 * to contain a value of the specified size. On some systems, like
108 * Crays, there is no such thing as an integer variable with 16 bits.
109 * Keep this in mind if you think this function should have been coded
110 * to use pointer overlays. All the world's not a VAX.
111 */
112 char tmp[sizeof "ffff:ffff:ffff:ffff:ffff:ffff:255.255.255.255"], *tp;
113 struct { int base, len; } best, cur;
114 u_int words[NS_IN6ADDRSZ / NS_INT16SZ];
115 int i;
116
117 /*
118 * Preprocess:
119 * Copy the input (bytewise) array into a wordwise array.
120 * Find the longest run of 0x00's in src[] for :: shorthanding.
121 */
122 memset(words, '\0', sizeof words);
123 for (i = 0; i < NS_IN6ADDRSZ; i += 2)
124 words[i / 2] = (src[i] << 8) | src[i + 1];
125 best.base = -1;
126 cur.base = -1;
127 best.len = 0;
128 cur.len = 0;
129 for (i = 0; i < (NS_IN6ADDRSZ / NS_INT16SZ); i++) {
130 if (words[i] == 0) {
131 if (cur.base == -1)
132 cur.base = i, cur.len = 1;
133 else
134 cur.len++;
135 } else {
136 if (cur.base != -1) {
137 if (best.base == -1 || cur.len > best.len)
138 best = cur;
139 cur.base = -1;
140 }
141 }
142 }
143 if (cur.base != -1) {
144 if (best.base == -1 || cur.len > best.len)
145 best = cur;
146 }
147 if (best.base != -1 && best.len < 2)
148 best.base = -1;
149
150 /*
151 * Format the result.
152 */
153 tp = tmp;
154 for (i = 0; i < (NS_IN6ADDRSZ / NS_INT16SZ); i++) {
155 /* Are we inside the best run of 0x00's? */
156 if (best.base != -1 && i >= best.base &&
157 i < (best.base + best.len)) {
158 if (i == best.base)
159 *tp++ = ':';
160 continue;
161 }
162 /* Are we following an initial run of 0x00s or any real hex? */
163 if (i != 0)
164 *tp++ = ':';
165 /* Is this address an encapsulated IPv4? */
166 if (i == 6 && best.base == 0 &&
167 (best.len == 6 || (best.len == 5 && words[5] == 0xffff))) {
168 if (!inet_ntop4(src+12, tp, sizeof tmp - (tp - tmp)))
169 return (NULL);
170 tp += strlen(tp);
171 break;
172 }
173 tp += SPRINTF((tp, "%x", words[i]));
174 }
175 /* Was it a trailing run of 0x00's? */
176 if (best.base != -1 && (best.base + best.len) ==
177 (NS_IN6ADDRSZ / NS_INT16SZ))
178 *tp++ = ':';
179 *tp++ = '\0';
180
181 /*
182 * Check for overflow, copy, and we're done.
183 */
184 if ((socklen_t)(tp - tmp) > size) {
185 __set_errno (ENOSPC);
186 return (NULL);
187 }
188 return strcpy(dst, tmp);
189}
190