lib/libc/inet/inet_cidr_ntop.c

   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 *
  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
  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 *
 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 *
 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 */