1 /*        $NetBSD: inet_cidr_ntop.c,v 1.1.1.2 2012/09/09 16:07:50 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 #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 
24 #include "port_before.h"
25 
26 #include <sys/types.h>
27 #include <sys/socket.h>
28 #include <netinet/in.h>
29 #include <arpa/nameser.h>
30 #include <arpa/inet.h>
31 
32 #include <errno.h>
33 #include <stdio.h>
34 #include <string.h>
35 #include <stdlib.h>
36 
37 #include "port_after.h"
38 
39 #ifdef SPRINTF_CHAR
40 # define SPRINTF(x) strlen(sprintf/**/x)
41 #else
42 # define SPRINTF(x) ((size_t)sprintf x)
43 #endif
44 
45 static char *
46 inet_cidr_ntop_ipv4(const u_char *src, int bits, char *dst, size_t size);
47 static char *
48 inet_cidr_ntop_ipv6(const u_char *src, int bits, char *dst, size_t size);
49 
50 /*%
51  * char *
52  * inet_cidr_ntop(af, src, bits, dst, size)
53  *        convert network address from network to presentation format.
54  *        "src"'s size is determined from its "af".
55  * return:
56  *        pointer to dst, or NULL if an error occurred (check errno).
57  * note:
58  *        192.5.5.1/28 has a nonzero host part, which means it isn't a network
59  *        as called for by inet_net_ntop() but it can be a host address with
60  *        an included netmask.
61  * author:
62  *        Paul Vixie (ISC), October 1998
63  */
64 char *
inet_cidr_ntop(int af,const void * src,int bits,char * dst,size_t size)65 inet_cidr_ntop(int af, const void *src, int bits, char *dst, size_t size) {
66           switch (af) {
67           case AF_INET:
68                     return (inet_cidr_ntop_ipv4(src, bits, dst, size));
69           case AF_INET6:
70                     return (inet_cidr_ntop_ipv6(src, bits, dst, size));
71           default:
72                     errno = EAFNOSUPPORT;
73                     return (NULL);
74           }
75 }
76 
77 static int
decoct(const u_char * src,int bytes,char * dst,size_t size)78 decoct(const u_char *src, int bytes, char *dst, size_t size) {
79           char *odst = dst;
80           char *t;
81           int b;
82 
83           for (b = 1; b <= bytes; b++) {
84                     if (size < sizeof "255.")
85                               return (0);
86                     t = dst;
87                     dst += SPRINTF((dst, "%u", *src++));
88                     if (b != bytes) {
89                               *dst++ = '.';
90                               *dst = '\0';
91                     }
92                     size -= (size_t)(dst - t);
93           }
94           return (dst - odst);
95 }
96 
97 /*%
98  * static char *
99  * inet_cidr_ntop_ipv4(src, bits, dst, size)
100  *        convert IPv4 network address from network to presentation format.
101  *        "src"'s size is determined from its "af".
102  * return:
103  *        pointer to dst, or NULL if an error occurred (check errno).
104  * note:
105  *        network byte order assumed.  this means 192.5.5.240/28 has
106  *        0b11110000 in its fourth octet.
107  * author:
108  *        Paul Vixie (ISC), October 1998
109  */
110 static char *
inet_cidr_ntop_ipv4(const u_char * src,int bits,char * dst,size_t size)111 inet_cidr_ntop_ipv4(const u_char *src, int bits, char *dst, size_t size) {
112           char *odst = dst;
113           size_t len = 4;
114           size_t b;
115           size_t bytes;
116 
117           if ((bits < -1) || (bits > 32)) {
118                     errno = EINVAL;
119                     return (NULL);
120           }
121 
122           /* Find number of significant bytes in address. */
123           if (bits == -1)
124                     len = 4;
125           else
126                     for (len = 1, b = 1 ; b < 4U; b++)
127                               if (*(src + b))
128                                         len = b + 1;
129 
130           /* Format whole octets plus nonzero trailing octets. */
131           bytes = (((bits <= 0) ? 1 : bits) + 7) / 8;
132           if (len > bytes)
133                     bytes = len;
134           b = decoct(src, bytes, dst, size);
135           if (b == 0U)
136                     goto emsgsize;
137           dst += b;
138           size -= b;
139 
140           if (bits != -1) {
141                     /* Format CIDR /width. */
142                     if (size < sizeof "/32")
143                               goto emsgsize;
144                     dst += SPRINTF((dst, "/%u", bits));
145           }
146 
147           return (odst);
148 
149  emsgsize:
150           errno = EMSGSIZE;
151           return (NULL);
152 }
153 
154 static char *
inet_cidr_ntop_ipv6(const u_char * src,int bits,char * dst,size_t size)155 inet_cidr_ntop_ipv6(const u_char *src, int bits, char *dst, size_t size) {
156           /*
157            * Note that int32_t and int16_t need only be "at least" large enough
158            * to contain a value of the specified size.  On some systems, like
159            * Crays, there is no such thing as an integer variable with 16 bits.
160            * Keep this in mind if you think this function should have been coded
161            * to use pointer overlays.  All the world's not a VAX.
162            */
163           char tmp[sizeof "ffff:ffff:ffff:ffff:ffff:ffff:255.255.255.255/128"];
164           char *tp;
165           struct { int base, len; } best, cur;
166           u_int words[NS_IN6ADDRSZ / NS_INT16SZ];
167           int i;
168 
169           if ((bits < -1) || (bits > 128)) {
170                     errno = EINVAL;
171                     return (NULL);
172           }
173 
174           /*
175            * Preprocess:
176            *        Copy the input (bytewise) array into a wordwise array.
177            *        Find the longest run of 0x00's in src[] for :: shorthanding.
178            */
179           memset(words, '\0', sizeof words);
180           for (i = 0; i < NS_IN6ADDRSZ; i++)
181                     words[i / 2] |= (src[i] << ((1 - (i % 2)) << 3));
182           best.base = -1;
183           best.len = 0;
184           cur.base = -1;
185           cur.len = 0;
186           for (i = 0; i < (NS_IN6ADDRSZ / NS_INT16SZ); i++) {
187                     if (words[i] == 0) {
188                               if (cur.base == -1)
189                                         cur.base = i, cur.len = 1;
190                               else
191                                         cur.len++;
192                     } else {
193                               if (cur.base != -1) {
194                                         if (best.base == -1 || cur.len > best.len)
195                                                   best = cur;
196                                         cur.base = -1;
197                               }
198                     }
199           }
200           if (cur.base != -1) {
201                     if (best.base == -1 || cur.len > best.len)
202                               best = cur;
203           }
204           if (best.base != -1 && best.len < 2)
205                     best.base = -1;
206 
207           /*
208            * Format the result.
209            */
210           tp = tmp;
211           for (i = 0; i < (NS_IN6ADDRSZ / NS_INT16SZ); i++) {
212                     /* Are we inside the best run of 0x00's? */
213                     if (best.base != -1 && i >= best.base &&
214                         i < (best.base + best.len)) {
215                               if (i == best.base)
216                                         *tp++ = ':';
217                               continue;
218                     }
219                     /* Are we following an initial run of 0x00s or any real hex? */
220                     if (i != 0)
221                               *tp++ = ':';
222                     /* Is this address an encapsulated IPv4? */
223                     if (i == 6 && best.base == 0 && (best.len == 6 ||
224                         (best.len == 7 && words[7] != 0x0001) ||
225                         (best.len == 5 && words[5] == 0xffff))) {
226                               int n;
227 
228                               if (src[15] || bits == -1 || bits > 120)
229                                         n = 4;
230                               else if (src[14] || bits > 112)
231                                         n = 3;
232                               else
233                                         n = 2;
234                               n = decoct(src+12, n, tp, sizeof tmp - (tp - tmp));
235                               if (n == 0) {
236                                         errno = EMSGSIZE;
237                                         return (NULL);
238                               }
239                               tp += strlen(tp);
240                               break;
241                     }
242                     tp += SPRINTF((tp, "%x", words[i]));
243           }
244 
245           /* Was it a trailing run of 0x00's? */
246           if (best.base != -1 && (best.base + best.len) ==
247               (NS_IN6ADDRSZ / NS_INT16SZ))
248                     *tp++ = ':';
249           *tp = '\0';
250 
251           if (bits != -1)
252                     tp += SPRINTF((tp, "/%u", bits));
253 
254           /*
255            * Check for overflow, copy, and we're done.
256            */
257           if ((size_t)(tp - tmp) > size) {
258                     errno = EMSGSIZE;
259                     return (NULL);
260           }
261           strcpy(dst, tmp);
262           return (dst);
263 }
264 
265 /*! \file */
266