1 /*
2 * Copyright (C) 2004, 2005, 2007, 2009 Internet Systems Consortium, Inc. ("ISC")
3 * Copyright (C) 1996-2001 Internet Software Consortium.
4 *
5 * Permission to use, copy, modify, and/or 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 WITH
10 * REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
11 * AND FITNESS. IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT,
12 * INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
13 * LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
14 * OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
15 * PERFORMANCE OF THIS SOFTWARE.
16 */
17
18 /*! \file */
19
20 #if defined(LIBC_SCCS) && !defined(lint)
21 static char rcsid[] =
22 "$Id: inet_ntop.c,v 1.21 2009/07/17 23:47:41 tbox Exp $";
23 #endif /* LIBC_SCCS and not lint */
24
25 #include <config.h>
26
27 #include <errno.h>
28 #include <stdio.h>
29 #include <string.h>
30
31 #include <isc/net.h>
32 #include <isc/print.h>
33
34 #define NS_INT16SZ 2
35 #define NS_IN6ADDRSZ 16
36
37 /*
38 * WARNING: Don't even consider trying to compile this on a system where
39 * sizeof(int) < 4. sizeof(int) > 4 is fine; all the world's not a VAX.
40 */
41
42 static const char *inet_ntop4(const unsigned char *src, char *dst,
43 size_t size);
44
45 #ifdef AF_INET6
46 static const char *inet_ntop6(const unsigned char *src, char *dst,
47 size_t size);
48 #endif
49 const char *isc_net_ntop(int af, const void *src, char *dst, size_t size);
50
51 /*! char *
52 * isc_net_ntop(af, src, dst, size)
53 * convert a network format address to presentation format.
54 * \return
55 * pointer to presentation format address (`dst'), or NULL (see errno).
56 * \author
57 * Paul Vixie, 1996.
58 */
59 const char *
isc_net_ntop(int af,const void * src,char * dst,size_t size)60 isc_net_ntop(int af, const void *src, char *dst, size_t size)
61 {
62 switch (af) {
63 case AF_INET:
64 return (inet_ntop4(src, dst, size));
65 #ifdef AF_INET6
66 case AF_INET6:
67 return (inet_ntop6(src, dst, size));
68 #endif
69 default:
70 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 * \note
82 * (1) uses no statics
83 * \note
84 * (2) takes a unsigned char* not an in_addr as input
85 * \author
86 * Paul Vixie, 1996.
87 */
88 static const char *
inet_ntop4(const unsigned char * src,char * dst,size_t size)89 inet_ntop4(const unsigned char *src, char *dst, size_t size)
90 {
91 static const char *fmt = "%u.%u.%u.%u";
92 char tmp[sizeof("255.255.255.255")];
93 int len;
94
95 len = snprintf(tmp, sizeof(tmp), fmt, src[0], src[1], src[2], src[3]);
96 if (len < 0 || (size_t)len >= size)
97 {
98 errno = ENOSPC;
99 return (NULL);
100 }
101 memcpy(dst, tmp, 1 + len);
102
103 return (dst);
104 }
105
106 /*! const char *
107 * isc_inet_ntop6(src, dst, size)
108 * convert IPv6 binary address into presentation (printable) format
109 * \author
110 * Paul Vixie, 1996.
111 */
112 #ifdef AF_INET6
113 static const char *
inet_ntop6(const unsigned char * src,char * dst,size_t size)114 inet_ntop6(const unsigned char *src, char *dst, size_t size)
115 {
116 /*
117 * Note that int32_t and int16_t need only be "at least" large enough
118 * to contain a value of the specified size. On some systems, like
119 * Crays, there is no such thing as an integer variable with 16 bits.
120 * Keep this in mind if you think this function should have been coded
121 * to use pointer overlays. All the world's not a VAX.
122 */
123 char tmp[sizeof("ffff:ffff:ffff:ffff:ffff:ffff:255.255.255.255")], *tp;
124 struct { int base, len; } best, cur;
125 unsigned int words[NS_IN6ADDRSZ / NS_INT16SZ];
126 int i;
127
128 /*
129 * Preprocess:
130 * Copy the input (bytewise) array into a wordwise array.
131 * Find the longest run of 0x00's in src[] for :: shorthanding.
132 */
133 memset(words, '\0', sizeof(words));
134 for (i = 0; i < NS_IN6ADDRSZ; i++)
135 words[i / 2] |= (src[i] << ((1 - (i % 2)) << 3));
136 best.base = -1;
137 cur.base = -1;
138 best.len = cur.len = 0;
139 for (i = 0; i < (NS_IN6ADDRSZ / NS_INT16SZ); i++) {
140 if (words[i] == 0) {
141 if (cur.base == -1)
142 cur.base = i, cur.len = 1;
143 else
144 cur.len++;
145 } else {
146 if (cur.base != -1) {
147 if (best.base == -1 || cur.len > best.len)
148 best = cur;
149 cur.base = -1;
150 }
151 }
152 }
153 if (cur.base != -1) {
154 if (best.base == -1 || cur.len > best.len)
155 best = cur;
156 }
157 if (best.base != -1 && best.len < 2)
158 best.base = -1;
159
160 /*
161 * Format the result.
162 */
163 tp = tmp;
164 for (i = 0; i < (NS_IN6ADDRSZ / NS_INT16SZ); i++) {
165 /* Are we inside the best run of 0x00's? */
166 if (best.base != -1 && i >= best.base &&
167 i < (best.base + best.len)) {
168 if (i == best.base)
169 *tp++ = ':';
170 continue;
171 }
172 /* Are we following an initial run of 0x00s or any real hex? */
173 if (i != 0)
174 *tp++ = ':';
175 /* Is this address an encapsulated IPv4? */
176 if (i == 6 && best.base == 0 && (best.len == 6 ||
177 (best.len == 7 && words[7] != 0x0001) ||
178 (best.len == 5 && words[5] == 0xffff))) {
179 if (!inet_ntop4(src+12, tp,
180 sizeof(tmp) - (tp - tmp)))
181 return (NULL);
182 tp += strlen(tp);
183 break;
184 }
185 tp += snprintf(tp, sizeof(tmp) - (tp - tmp), "%x", words[i]);
186 }
187 /* Was it a trailing run of 0x00's? */
188 if (best.base != -1 && (best.base + best.len) ==
189 (NS_IN6ADDRSZ / NS_INT16SZ))
190 *tp++ = ':';
191 *tp++ = '\0';
192
193 /*
194 * Check for overflow, copy, and we're done.
195 */
196 if ((size_t)(tp - tmp) > size) {
197 errno = ENOSPC;
198 return (NULL);
199 }
200 memcpy(dst, tmp, (size_t)(tp - tmp));
201 return (dst);
202 }
203 #endif /* AF_INET6 */
204