1 /* $NetBSD: inet_cidr_ntop.c,v 1.8 2012/03/13 21:13:38 christos Exp $ */
2
3 /*
4 * Copyright (c) 2004 by Internet Systems Consortium, Inc. ("ISC")
5 * Copyright (c) 1998,1999 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 <sys/cdefs.h>
21 #if defined(LIBC_SCCS) && !defined(lint)
22 #if 0
23 static const char rcsid[] = "Id: inet_cidr_ntop.c,v 1.7 2006/10/11 02:18:18 marka Exp";
24 #else
25 __RCSID("$NetBSD: inet_cidr_ntop.c,v 1.8 2012/03/13 21:13:38 christos Exp $");
26 #endif
27 #endif
28
29 #include "port_before.h"
30
31 #include "namespace.h"
32 #include <sys/types.h>
33 #include <sys/socket.h>
34 #include <netinet/in.h>
35 #include <arpa/nameser.h>
36 #include <arpa/inet.h>
37
38 #include <assert.h>
39 #include <errno.h>
40 #include <stdio.h>
41 #include <string.h>
42 #include <stdlib.h>
43
44 #include "port_after.h"
45
46 #ifdef __weak_alias
47 __weak_alias(inet_cidr_ntop,_inet_cidr_ntop)
48 #endif
49
50 #ifdef SPRINTF_CHAR
51 # define SPRINTF(x) strlen(sprintf/**/x)
52 #else
53 # define SPRINTF(x) ((size_t)sprintf x)
54 #endif
55
56 static char *
57 inet_cidr_ntop_ipv4(const u_char *src, int bits, char *dst, size_t size);
58 static char *
59 inet_cidr_ntop_ipv6(const u_char *src, int bits, char *dst, size_t size);
60
61 /*%
62 * char *
63 * inet_cidr_ntop(af, src, bits, dst, size)
64 * convert network address from network to presentation format.
65 * "src"'s size is determined from its "af".
66 * return:
67 * pointer to dst, or NULL if an error occurred (check errno).
68 * note:
69 * 192.5.5.1/28 has a nonzero host part, which means it isn't a network
70 * as called for by inet_net_ntop() but it can be a host address with
71 * an included netmask.
72 * author:
73 * Paul Vixie (ISC), October 1998
74 */
75 char *
inet_cidr_ntop(int af,const void * src,int bits,char * dst,size_t size)76 inet_cidr_ntop(int af, const void *src, int bits, char *dst, size_t size) {
77 switch (af) {
78 case AF_INET:
79 return (inet_cidr_ntop_ipv4(src, bits, dst, size));
80 case AF_INET6:
81 return (inet_cidr_ntop_ipv6(src, bits, dst, size));
82 default:
83 errno = EAFNOSUPPORT;
84 return (NULL);
85 }
86 }
87
88 static int
decoct(const u_char * src,size_t bytes,char * dst,size_t size)89 decoct(const u_char *src, size_t bytes, char *dst, size_t size) {
90 char *odst = dst;
91 char *t;
92 size_t b;
93
94 for (b = 1; b <= bytes; b++) {
95 if (size < sizeof "255.")
96 return (0);
97 t = dst;
98 dst += SPRINTF((dst, "%u", *src++));
99 if (b != bytes) {
100 *dst++ = '.';
101 *dst = '\0';
102 }
103 size -= (size_t)(dst - t);
104 }
105 _DIAGASSERT(__type_fit(int, dst - odst));
106 return (int)(dst - odst);
107 }
108
109 /*%
110 * static char *
111 * inet_cidr_ntop_ipv4(src, bits, dst, size)
112 * convert IPv4 network address from network to presentation format.
113 * "src"'s size is determined from its "af".
114 * return:
115 * pointer to dst, or NULL if an error occurred (check errno).
116 * note:
117 * network byte order assumed. this means 192.5.5.240/28 has
118 * 0b11110000 in its fourth octet.
119 * author:
120 * Paul Vixie (ISC), October 1998
121 */
122 static char *
inet_cidr_ntop_ipv4(const u_char * src,int bits,char * dst,size_t size)123 inet_cidr_ntop_ipv4(const u_char *src, int bits, char *dst, size_t size) {
124 char *odst = dst;
125 size_t len = 4;
126 size_t b;
127 size_t bytes;
128
129 if ((bits < -1) || (bits > 32)) {
130 errno = EINVAL;
131 return (NULL);
132 }
133
134 /* Find number of significant bytes in address. */
135 if (bits == -1)
136 len = 4;
137 else
138 for (len = 1, b = 1 ; b < 4U; b++)
139 if (*(src + b))
140 len = b + 1;
141
142 /* Format whole octets plus nonzero trailing octets. */
143 bytes = (((bits <= 0) ? 1 : bits) + 7) / 8;
144 if (len > bytes)
145 bytes = len;
146 b = decoct(src, bytes, dst, size);
147 if (b == 0U)
148 goto emsgsize;
149 dst += b;
150 size -= b;
151
152 if (bits != -1) {
153 /* Format CIDR /width. */
154 if (size < sizeof "/32")
155 goto emsgsize;
156 dst += SPRINTF((dst, "/%u", bits));
157 }
158
159 return (odst);
160
161 emsgsize:
162 errno = EMSGSIZE;
163 return (NULL);
164 }
165
166 static char *
inet_cidr_ntop_ipv6(const u_char * src,int bits,char * dst,size_t size)167 inet_cidr_ntop_ipv6(const u_char *src, int bits, char *dst, size_t size) {
168 /*
169 * Note that int32_t and int16_t need only be "at least" large enough
170 * to contain a value of the specified size. On some systems, like
171 * Crays, there is no such thing as an integer variable with 16 bits.
172 * Keep this in mind if you think this function should have been coded
173 * to use pointer overlays. All the world's not a VAX.
174 */
175 char tmp[sizeof "ffff:ffff:ffff:ffff:ffff:ffff:255.255.255.255/128"];
176 char *tp;
177 struct { int base, len; } best, cur;
178 u_int words[NS_IN6ADDRSZ / NS_INT16SZ];
179 int i;
180
181 if ((bits < -1) || (bits > 128)) {
182 errno = EINVAL;
183 return (NULL);
184 }
185
186 /*
187 * Preprocess:
188 * Copy the input (bytewise) array into a wordwise array.
189 * Find the longest run of 0x00's in src[] for :: shorthanding.
190 */
191 memset(words, '\0', sizeof words);
192 for (i = 0; i < NS_IN6ADDRSZ; i++)
193 words[i / 2] |= (src[i] << ((1 - (i % 2)) << 3));
194 best.base = -1;
195 best.len = 0;
196 cur.base = -1;
197 cur.len = 0;
198 for (i = 0; i < (NS_IN6ADDRSZ / NS_INT16SZ); i++) {
199 if (words[i] == 0) {
200 if (cur.base == -1)
201 cur.base = i, cur.len = 1;
202 else
203 cur.len++;
204 } else {
205 if (cur.base != -1) {
206 if (best.base == -1 || cur.len > best.len)
207 best = cur;
208 cur.base = -1;
209 }
210 }
211 }
212 if (cur.base != -1) {
213 if (best.base == -1 || cur.len > best.len)
214 best = cur;
215 }
216 if (best.base != -1 && best.len < 2)
217 best.base = -1;
218
219 /*
220 * Format the result.
221 */
222 tp = tmp;
223 for (i = 0; i < (NS_IN6ADDRSZ / NS_INT16SZ); i++) {
224 /* Are we inside the best run of 0x00's? */
225 if (best.base != -1 && i >= best.base &&
226 i < (best.base + best.len)) {
227 if (i == best.base)
228 *tp++ = ':';
229 continue;
230 }
231 /* Are we following an initial run of 0x00s or any real hex? */
232 if (i != 0)
233 *tp++ = ':';
234 /* Is this address an encapsulated IPv4? */
235 if (i == 6 && best.base == 0 && (best.len == 6 ||
236 (best.len == 7 && words[7] != 0x0001) ||
237 (best.len == 5 && words[5] == 0xffff))) {
238 size_t n;
239
240 if (src[15] || bits == -1 || bits > 120)
241 n = 4;
242 else if (src[14] || bits > 112)
243 n = 3;
244 else
245 n = 2;
246 n = decoct(src+12, n, tp, sizeof tmp - (tp - tmp));
247 if (n == 0) {
248 errno = EMSGSIZE;
249 return (NULL);
250 }
251 tp += strlen(tp);
252 break;
253 }
254 tp += SPRINTF((tp, "%x", words[i]));
255 }
256
257 /* Was it a trailing run of 0x00's? */
258 if (best.base != -1 && (best.base + best.len) ==
259 (NS_IN6ADDRSZ / NS_INT16SZ))
260 *tp++ = ':';
261 *tp = '\0';
262
263 if (bits != -1)
264 tp += SPRINTF((tp, "/%u", bits));
265
266 /*
267 * Check for overflow, copy, and we're done.
268 */
269 if ((size_t)(tp - tmp) > size) {
270 errno = EMSGSIZE;
271 return (NULL);
272 }
273 strcpy(dst, tmp);
274 return (dst);
275 }
276
277 /*! \file */
278