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