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 "port_before.h"
24
25 #include <sys/param.h>
26 #include <sys/socket.h>
27
28 #include <netinet/in.h>
29 #include <arpa/inet.h>
30 #include <arpa/nameser.h>
31
32 #include <errno.h>
33 #include <stdio.h>
34 #include <string.h>
35
36 #include "port_after.h"
37
38 /*%
39 * WARNING: Don't even consider trying to compile this on a system where
40 * sizeof(int) < 4. sizeof(int) > 4 is fine; all the world's not a VAX.
41 */
42
43 static const char *inet_ntop4(const u_char *src, char *dst, socklen_t size);
44 static const char *inet_ntop6(const u_char *src, char *dst, socklen_t size);
45
46 /* const 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 */
54 const char *
inet_ntop(int af,const void * __restrict src,char * __restrict dst,socklen_t size)55 inet_ntop(int af, const void * __restrict src, char * __restrict 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
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(const u_char * src,char * dst,socklen_t size)82 inet_ntop4(const u_char *src, char *dst, socklen_t size)
83 {
84 static const char fmt[] = "%u.%u.%u.%u";
85 char tmp[sizeof "255.255.255.255"];
86 int l;
87
88 l = snprintf(tmp, sizeof(tmp), fmt, src[0], src[1], src[2], src[3]);
89 if (l <= 0 || (socklen_t) l >= size) {
90 errno = ENOSPC;
91 return (NULL);
92 }
93 strlcpy(dst, tmp, size);
94 return (dst);
95 }
96
97 /* const char *
98 * inet_ntop6(src, dst, size)
99 * convert IPv6 binary address into presentation (printable) format
100 * author:
101 * Paul Vixie, 1996.
102 */
103 static const char *
inet_ntop6(const u_char * src,char * dst,socklen_t size)104 inet_ntop6(const u_char *src, char *dst, socklen_t size)
105 {
106 /*
107 * Note that int32_t and int16_t need only be "at least" large enough
108 * to contain a value of the specified size. On some systems, like
109 * Crays, there is no such thing as an integer variable with 16 bits.
110 * Keep this in mind if you think this function should have been coded
111 * to use pointer overlays. All the world's not a VAX.
112 */
113 char tmp[sizeof "ffff:ffff:ffff:ffff:ffff:ffff:255.255.255.255"], *tp;
114 struct { int base, len; } best, cur;
115 u_int words[NS_IN6ADDRSZ / NS_INT16SZ];
116 int i;
117
118 /*
119 * Preprocess:
120 * Copy the input (bytewise) array into a wordwise array.
121 * Find the longest run of 0x00's in src[] for :: shorthanding.
122 */
123 memset(words, '\0', sizeof words);
124 for (i = 0; i < NS_IN6ADDRSZ; i++)
125 words[i / 2] |= (src[i] << ((1 - (i % 2)) << 3));
126 best.base = -1;
127 best.len = 0;
128 cur.base = -1;
129 cur.len = 0;
130 for (i = 0; i < (NS_IN6ADDRSZ / NS_INT16SZ); i++) {
131 if (words[i] == 0) {
132 if (cur.base == -1)
133 cur.base = i, cur.len = 1;
134 else
135 cur.len++;
136 } else {
137 if (cur.base != -1) {
138 if (best.base == -1 || cur.len > best.len)
139 best = cur;
140 cur.base = -1;
141 }
142 }
143 }
144 if (cur.base != -1) {
145 if (best.base == -1 || cur.len > best.len)
146 best = cur;
147 }
148 if (best.base != -1 && best.len < 2)
149 best.base = -1;
150
151 /*
152 * Format the result.
153 */
154 tp = tmp;
155 for (i = 0; i < (NS_IN6ADDRSZ / NS_INT16SZ); i++) {
156 /* Are we inside the best run of 0x00's? */
157 if (best.base != -1 && i >= best.base &&
158 i < (best.base + best.len)) {
159 if (i == best.base)
160 *tp++ = ':';
161 continue;
162 }
163 /* Are we following an initial run of 0x00s or any real hex? */
164 if (i != 0)
165 *tp++ = ':';
166 /* Is this address an encapsulated IPv4? */
167 if (i == 6 && best.base == 0 && (best.len == 6 ||
168 (best.len == 7 && words[7] != 0x0001) ||
169 (best.len == 5 && words[5] == 0xffff))) {
170 if (!inet_ntop4(src+12, tp, sizeof tmp - (tp - tmp))) {
171 errno = ENOSPC;
172 return (NULL);
173 }
174 tp += strlen(tp);
175 break;
176 }
177 tp += sprintf(tp, "%x", words[i]);
178 }
179 /* Was it a trailing run of 0x00's? */
180 if (best.base != -1 && (best.base + best.len) ==
181 (NS_IN6ADDRSZ / NS_INT16SZ))
182 *tp++ = ':';
183 *tp++ = '\0';
184
185 /*
186 * Check for overflow, copy, and we're done.
187 */
188 if ((socklen_t)(tp - tmp) > size) {
189 errno = ENOSPC;
190 return (NULL);
191 }
192 strcpy(dst, tmp);
193 return (dst);
194 }
195
196 /*
197 * Weak aliases for applications that use certain private entry points,
198 * and fail to include <arpa/inet.h>.
199 */
200 #undef inet_ntop
201 __weak_reference(__inet_ntop, inet_ntop);
202
203 /*! \file */
204