1 /*
2 * Copyright (c) 2004 by Internet Systems Consortium, Inc. ("ISC")
3 * Copyright (c) 1996-1999 by Internet Software Consortium.
4 *
5 * Permission to use, copy, modify, and distribute this software for any
6 * purpose with or without fee is hereby granted, provided that the above
7 * copyright notice and this permission notice appear in all copies.
8 *
9 * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES
10 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
11 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL ISC BE LIABLE FOR
12 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
13 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
14 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT
15 * OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
16 */
17
18 #include "ares_setup.h"
19
20 #ifdef HAVE_NETINET_IN_H
21 # include <netinet/in.h>
22 #endif
23 #ifdef HAVE_ARPA_INET_H
24 # include <arpa/inet.h>
25 #endif
26 #ifdef HAVE_ARPA_NAMESER_H
27 # include <arpa/nameser.h>
28 #else
29 # include "nameser.h"
30 #endif
31 #ifdef HAVE_ARPA_NAMESER_COMPAT_H
32 # include <arpa/nameser_compat.h>
33 #endif
34
35 #include "ares.h"
36 #include "ares_ipv6.h"
37
38 #ifndef HAVE_INET_NTOP
39
40 /*
41 * WARNING: Don't even consider trying to compile this on a system where
42 * sizeof(int) < 4. sizeof(int) > 4 is fine; all the world's not a VAX.
43 */
44
45 static const char *inet_ntop4(const unsigned char *src, char *dst, size_t size);
46 static const char *inet_ntop6(const unsigned char *src, char *dst, size_t size);
47
48 /* char *
49 * inet_ntop(af, src, dst, size)
50 * convert a network format address to presentation format.
51 * return:
52 * pointer to presentation format address (`dst'), or NULL (see errno).
53 * note:
54 * On Windows we store the error in the thread errno, not
55 * in the winsock error code. This is to avoid loosing the
56 * actual last winsock error. So use macro ERRNO to fetch the
57 * errno this function sets when returning NULL, not SOCKERRNO.
58 * author:
59 * Paul Vixie, 1996.
60 */
61 const char *
ares_inet_ntop(int af,const void * src,char * dst,ares_socklen_t size)62 ares_inet_ntop(int af, const void *src, char *dst, ares_socklen_t size)
63 {
64 switch (af) {
65 case AF_INET:
66 return (inet_ntop4(src, dst, (size_t)size));
67 case AF_INET6:
68 return (inet_ntop6(src, dst, (size_t)size));
69 default:
70 SET_ERRNO(EAFNOSUPPORT);
71 return (NULL);
72 }
73 /* NOTREACHED */
74 }
75
76 /* const char *
77 * inet_ntop4(src, dst, size)
78 * format an IPv4 address
79 * return:
80 * `dst' (as a const)
81 * notes:
82 * (1) uses no statics
83 * (2) takes a unsigned char* not an in_addr as input
84 * author:
85 * Paul Vixie, 1996.
86 */
87 static const char *
inet_ntop4(const unsigned char * src,char * dst,size_t size)88 inet_ntop4(const unsigned char *src, char *dst, size_t size)
89 {
90 static const char fmt[] = "%u.%u.%u.%u";
91 char tmp[sizeof("255.255.255.255")];
92
93 if ((size_t)sprintf(tmp, fmt, src[0], src[1], src[2], src[3]) >= size) {
94 SET_ERRNO(ENOSPC);
95 return (NULL);
96 }
97 strcpy(dst, tmp);
98 return (dst);
99 }
100
101 /* const char *
102 * inet_ntop6(src, dst, size)
103 * convert IPv6 binary address into presentation (printable) format
104 * author:
105 * Paul Vixie, 1996.
106 */
107 static const char *
inet_ntop6(const unsigned char * src,char * dst,size_t size)108 inet_ntop6(const unsigned char *src, char *dst, size_t size)
109 {
110 /*
111 * Note that int32_t and int16_t need only be "at least" large enough
112 * to contain a value of the specified size. On some systems, like
113 * Crays, there is no such thing as an integer variable with 16 bits.
114 * Keep this in mind if you think this function should have been coded
115 * to use pointer overlays. All the world's not a VAX.
116 */
117 char tmp[sizeof("ffff:ffff:ffff:ffff:ffff:ffff:255.255.255.255")];
118 char *tp;
119 struct { int base, len; } best, cur;
120 unsigned int words[NS_IN6ADDRSZ / NS_INT16SZ];
121 int i;
122
123 /*
124 * Preprocess:
125 * Copy the input (bytewise) array into a wordwise array.
126 * Find the longest run of 0x00's in src[] for :: shorthanding.
127 */
128 memset(words, '\0', sizeof(words));
129 for (i = 0; i < NS_IN6ADDRSZ; i++)
130 words[i / 2] |= (src[i] << ((1 - (i % 2)) << 3));
131 best.base = -1;
132 best.len = 0;
133 cur.base = -1;
134 cur.len = 0;
135 for (i = 0; i < (NS_IN6ADDRSZ / NS_INT16SZ); i++) {
136 if (words[i] == 0) {
137 if (cur.base == -1)
138 cur.base = i, cur.len = 1;
139 else
140 cur.len++;
141 } else {
142 if (cur.base != -1) {
143 if (best.base == -1 || cur.len > best.len)
144 best = cur;
145 cur.base = -1;
146 }
147 }
148 }
149 if (cur.base != -1) {
150 if (best.base == -1 || cur.len > best.len)
151 best = cur;
152 }
153 if (best.base != -1 && best.len < 2)
154 best.base = -1;
155
156 /*
157 * Format the result.
158 */
159 tp = tmp;
160 for (i = 0; i < (NS_IN6ADDRSZ / NS_INT16SZ); i++) {
161 /* Are we inside the best run of 0x00's? */
162 if (best.base != -1 && i >= best.base &&
163 i < (best.base + best.len)) {
164 if (i == best.base)
165 *tp++ = ':';
166 continue;
167 }
168 /* Are we following an initial run of 0x00s or any real hex? */
169 if (i != 0)
170 *tp++ = ':';
171 /* Is this address an encapsulated IPv4? */
172 if (i == 6 && best.base == 0 && (best.len == 6 ||
173 (best.len == 7 && words[7] != 0x0001) ||
174 (best.len == 5 && words[5] == 0xffff))) {
175 if (!inet_ntop4(src+12, tp, sizeof(tmp) - (tp - tmp)))
176 return (NULL);
177 tp += strlen(tp);
178 break;
179 }
180 tp += sprintf(tp, "%x", words[i]);
181 }
182 /* Was it a trailing run of 0x00's? */
183 if (best.base != -1 && (best.base + best.len) == (NS_IN6ADDRSZ / NS_INT16SZ))
184 *tp++ = ':';
185 *tp++ = '\0';
186
187 /*
188 * Check for overflow, copy, and we're done.
189 */
190 if ((size_t)(tp - tmp) > size) {
191 SET_ERRNO(ENOSPC);
192 return (NULL);
193 }
194 strcpy(dst, tmp);
195 return (dst);
196 }
197
198 #else /* HAVE_INET_NTOP */
199
200 const char *
ares_inet_ntop(int af,const void * src,char * dst,ares_socklen_t size)201 ares_inet_ntop(int af, const void *src, char *dst, ares_socklen_t size)
202 {
203 /* just relay this to the underlying function */
204 return inet_ntop(af, src, dst, size);
205 }
206
207 #endif /* HAVE_INET_NTOP */
208