1 /*-
2 * SPDX-License-Identifier: ISC
3 *
4 * Copyright (c) 2004 by Internet Systems Consortium, Inc. ("ISC")
5 * Copyright (c) 1996-1999 by Internet Software Consortium.
6 *
7 * Permission to use, copy, modify, and distribute this software for any
8 * purpose with or without fee is hereby granted, provided that the above
9 * copyright notice and this permission notice appear in all copies.
10 *
11 * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES
12 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
13 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL ISC BE LIABLE FOR
14 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
15 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
16 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT
17 * OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
18 */
19
20 #include "port_before.h"
21
22 #include <sys/param.h>
23 #include <sys/socket.h>
24
25 #include <netinet/in.h>
26 #include <arpa/inet.h>
27 #include <arpa/nameser.h>
28
29 #include <errno.h>
30 #include <stdio.h>
31 #include <string.h>
32
33 #include "port_after.h"
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 /* const 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(int af,const void * __restrict src,char * __restrict dst,socklen_t size)52 inet_ntop(int af, const void * __restrict src, char * __restrict dst,
53 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 errno = EAFNOSUPPORT;
62 return (NULL);
63 }
64 /* NOTREACHED */
65 }
66
67 /* const char *
68 * inet_ntop4(src, dst, size)
69 * format an IPv4 address
70 * return:
71 * `dst' (as a const)
72 * notes:
73 * (1) uses no statics
74 * (2) takes a u_char* not an in_addr as input
75 * author:
76 * Paul Vixie, 1996.
77 */
78 static const char *
inet_ntop4(const u_char * src,char * dst,socklen_t size)79 inet_ntop4(const u_char *src, char *dst, socklen_t size)
80 {
81 static const char fmt[] = "%u.%u.%u.%u";
82 char tmp[sizeof "255.255.255.255"];
83 int l;
84
85 l = snprintf(tmp, sizeof(tmp), fmt, src[0], src[1], src[2], src[3]);
86 if (l <= 0 || (socklen_t) l >= size) {
87 errno = ENOSPC;
88 return (NULL);
89 }
90 strlcpy(dst, tmp, size);
91 return (dst);
92 }
93
94 /* const char *
95 * inet_ntop6(src, dst, size)
96 * convert IPv6 binary address into presentation (printable) format
97 * author:
98 * Paul Vixie, 1996.
99 */
100 static const char *
inet_ntop6(const u_char * src,char * dst,socklen_t size)101 inet_ntop6(const u_char *src, char *dst, socklen_t size)
102 {
103 /*
104 * Note that int32_t and int16_t need only be "at least" large enough
105 * to contain a value of the specified size. On some systems, like
106 * Crays, there is no such thing as an integer variable with 16 bits.
107 * Keep this in mind if you think this function should have been coded
108 * to use pointer overlays. All the world's not a VAX.
109 */
110 char tmp[sizeof "ffff:ffff:ffff:ffff:ffff:ffff:255.255.255.255"], *tp;
111 struct { int base, len; } best, cur;
112 u_int words[NS_IN6ADDRSZ / NS_INT16SZ];
113 int i;
114
115 /*
116 * Preprocess:
117 * Copy the input (bytewise) array into a wordwise array.
118 * Find the longest run of 0x00's in src[] for :: shorthanding.
119 */
120 memset(words, '\0', sizeof words);
121 for (i = 0; i < NS_IN6ADDRSZ; i++)
122 words[i / 2] |= (src[i] << ((1 - (i % 2)) << 3));
123 best.base = -1;
124 best.len = 0;
125 cur.base = -1;
126 cur.len = 0;
127 for (i = 0; i < (NS_IN6ADDRSZ / NS_INT16SZ); i++) {
128 if (words[i] == 0) {
129 if (cur.base == -1)
130 cur.base = i, cur.len = 1;
131 else
132 cur.len++;
133 } else {
134 if (cur.base != -1) {
135 if (best.base == -1 || cur.len > best.len)
136 best = cur;
137 cur.base = -1;
138 }
139 }
140 }
141 if (cur.base != -1) {
142 if (best.base == -1 || cur.len > best.len)
143 best = cur;
144 }
145 if (best.base != -1 && best.len < 2)
146 best.base = -1;
147
148 /*
149 * Format the result.
150 */
151 tp = tmp;
152 for (i = 0; i < (NS_IN6ADDRSZ / NS_INT16SZ); i++) {
153 /* Are we inside the best run of 0x00's? */
154 if (best.base != -1 && i >= best.base &&
155 i < (best.base + best.len)) {
156 if (i == best.base)
157 *tp++ = ':';
158 continue;
159 }
160 /* Are we following an initial run of 0x00s or any real hex? */
161 if (i != 0)
162 *tp++ = ':';
163 /* Is this address an encapsulated IPv4? */
164 if (i == 6 && best.base == 0 && (best.len == 6 ||
165 (best.len == 7 && words[7] != 0x0001) ||
166 (best.len == 5 && words[5] == 0xffff))) {
167 if (!inet_ntop4(src+12, tp, sizeof tmp - (tp - tmp))) {
168 errno = ENOSPC;
169 return (NULL);
170 }
171 tp += strlen(tp);
172 break;
173 }
174 tp += sprintf(tp, "%x", words[i]);
175 }
176 /* Was it a trailing run of 0x00's? */
177 if (best.base != -1 && (best.base + best.len) ==
178 (NS_IN6ADDRSZ / NS_INT16SZ))
179 *tp++ = ':';
180 *tp++ = '\0';
181
182 /*
183 * Check for overflow, copy, and we're done.
184 */
185 if ((socklen_t)(tp - tmp) > size) {
186 errno = ENOSPC;
187 return (NULL);
188 }
189 strcpy(dst, tmp);
190 return (dst);
191 }
192
193 /*
194 * Weak aliases for applications that use certain private entry points,
195 * and fail to include <arpa/inet.h>.
196 */
197 #undef inet_ntop
198 __weak_reference(__inet_ntop, inet_ntop);
199
200 /*! \file */
201