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 #if defined(LIBC_SCCS) && !defined(lint)
21 static const char rcsid[] = "$Id: inet_ntop.c,v 1.5 2005/11/03 22:59:52 marka Exp $";
22 #endif /* LIBC_SCCS and not lint */
23 #include <sys/cdefs.h>
24 #include "port_before.h"
25
26 #include <sys/param.h>
27 #include <sys/socket.h>
28
29 #include <netinet/in.h>
30 #include <arpa/inet.h>
31 #include <arpa/nameser.h>
32
33 #include <errno.h>
34 #include <stdio.h>
35 #include <string.h>
36
37 #include "port_after.h"
38
39 /*%
40 * WARNING: Don't even consider trying to compile this on a system where
41 * sizeof(int) < 4. sizeof(int) > 4 is fine; all the world's not a VAX.
42 */
43
44 static const char *inet_ntop4(const u_char *src, char *dst, socklen_t size);
45 static const char *inet_ntop6(const u_char *src, char *dst, socklen_t size);
46
47 /* const char *
48 * inet_ntop(af, src, dst, size)
49 * convert a network format address to presentation format.
50 * return:
51 * pointer to presentation format address (`dst'), or NULL (see errno).
52 * author:
53 * Paul Vixie, 1996.
54 */
55 const char *
inet_ntop(int af,const void * __restrict src,char * __restrict dst,socklen_t size)56 inet_ntop(int af, const void * __restrict src, char * __restrict dst,
57 socklen_t size)
58 {
59 switch (af) {
60 case AF_INET:
61 return (inet_ntop4(src, dst, size));
62 case AF_INET6:
63 return (inet_ntop6(src, dst, size));
64 default:
65 errno = EAFNOSUPPORT;
66 return (NULL);
67 }
68 /* NOTREACHED */
69 }
70
71 /* const char *
72 * inet_ntop4(src, dst, size)
73 * format an IPv4 address
74 * return:
75 * `dst' (as a const)
76 * notes:
77 * (1) uses no statics
78 * (2) takes a u_char* not an in_addr as input
79 * author:
80 * Paul Vixie, 1996.
81 */
82 static const char *
inet_ntop4(const u_char * src,char * dst,socklen_t size)83 inet_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 int l;
88
89 l = snprintf(tmp, sizeof(tmp), fmt, src[0], src[1], src[2], src[3]);
90 if (l <= 0 || (socklen_t) l >= size) {
91 errno = ENOSPC;
92 return (NULL);
93 }
94 strlcpy(dst, tmp, size);
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(const u_char * src,char * dst,socklen_t size)105 inet_ntop6(const u_char *src, char *dst, socklen_t size)
106 {
107 /*
108 * Note that int32_t and int16_t need only be "at least" large enough
109 * to contain a value of the specified size. On some systems, like
110 * Crays, there is no such thing as an integer variable with 16 bits.
111 * Keep this in mind if you think this function should have been coded
112 * to use pointer overlays. All the world's not a VAX.
113 */
114 char tmp[sizeof "ffff:ffff:ffff:ffff:ffff:ffff:255.255.255.255"], *tp;
115 struct { int base, len; } best, cur;
116 u_int words[NS_IN6ADDRSZ / NS_INT16SZ];
117 int i;
118
119 /*
120 * Preprocess:
121 * Copy the input (bytewise) array into a wordwise array.
122 * Find the longest run of 0x00's in src[] for :: shorthanding.
123 */
124 memset(words, '\0', sizeof words);
125 for (i = 0; i < NS_IN6ADDRSZ; i++)
126 words[i / 2] |= (src[i] << ((1 - (i % 2)) << 3));
127 best.base = -1;
128 best.len = 0;
129 cur.base = -1;
130 cur.len = 0;
131 for (i = 0; i < (NS_IN6ADDRSZ / NS_INT16SZ); i++) {
132 if (words[i] == 0) {
133 if (cur.base == -1)
134 cur.base = i, cur.len = 1;
135 else
136 cur.len++;
137 } else {
138 if (cur.base != -1) {
139 if (best.base == -1 || cur.len > best.len)
140 best = cur;
141 cur.base = -1;
142 }
143 }
144 }
145 if (cur.base != -1) {
146 if (best.base == -1 || cur.len > best.len)
147 best = cur;
148 }
149 if (best.base != -1 && best.len < 2)
150 best.base = -1;
151
152 /*
153 * Format the result.
154 */
155 tp = tmp;
156 for (i = 0; i < (NS_IN6ADDRSZ / NS_INT16SZ); i++) {
157 /* Are we inside the best run of 0x00's? */
158 if (best.base != -1 && i >= best.base &&
159 i < (best.base + best.len)) {
160 if (i == best.base)
161 *tp++ = ':';
162 continue;
163 }
164 /* Are we following an initial run of 0x00s or any real hex? */
165 if (i != 0)
166 *tp++ = ':';
167 /* Is this address an encapsulated IPv4? */
168 if (i == 6 && best.base == 0 && (best.len == 6 ||
169 (best.len == 7 && words[7] != 0x0001) ||
170 (best.len == 5 && words[5] == 0xffff))) {
171 if (!inet_ntop4(src+12, tp, sizeof tmp - (tp - tmp))) {
172 errno = ENOSPC;
173 return (NULL);
174 }
175 tp += strlen(tp);
176 break;
177 }
178 tp += sprintf(tp, "%x", words[i]);
179 }
180 /* Was it a trailing run of 0x00's? */
181 if (best.base != -1 && (best.base + best.len) ==
182 (NS_IN6ADDRSZ / NS_INT16SZ))
183 *tp++ = ':';
184 *tp++ = '\0';
185
186 /*
187 * Check for overflow, copy, and we're done.
188 */
189 if ((socklen_t)(tp - tmp) > size) {
190 errno = ENOSPC;
191 return (NULL);
192 }
193 strcpy(dst, tmp);
194 return (dst);
195 }
196
197 /*
198 * Weak aliases for applications that use certain private entry points,
199 * and fail to include <arpa/inet.h>.
200 */
201 #undef inet_ntop
202 __weak_reference(__inet_ntop, inet_ntop);
203
204 /*! \file */
205