lib/inet_ntop.c

   1 /* inet_ntop.c -- convert IPv4 and IPv6 addresses from binary to text form
   2
   3    Copyright (C) 2005-2006, 2008-2011 Free Software Foundation, Inc.
   4
   5    This program is free software; you can redistribute it and/or modify
   6    it under the terms of the GNU Lesser General Public License as published by
   7    the Free Software Foundation; either version 2, or (at your option)
   8    any later version.
   9
  10    This program is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13    GNU Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public License
  16    along with this program; if not, write to the Free Software Foundation,
  17    Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.  */
  18
  19 /*
  20  * Copyright (c) 1996-1999 by Internet Software Consortium.
  21  *
  22  * Permission to use, copy, modify, and distribute this software for any
  23  * purpose with or without fee is hereby granted, provided that the above
  24  * copyright notice and this permission notice appear in all copies.
  25  *
  26  * THE SOFTWARE IS PROVIDED "AS IS" AND INTERNET SOFTWARE CONSORTIUM DISCLAIMS
  27  * ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES
  28  * OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL INTERNET SOFTWARE
  29  * CONSORTIUM BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
  30  * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
  31  * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
  32  * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
  33  * SOFTWARE.
  34  */
  35
  36 #include <config.h>
  37
  38 /* Specification.  */
  39 #include <arpa/inet.h>
  40
  41 #if HAVE_DECL_INET_NTOP
  42
  43 # undef inet_ntop
  44
  45 const char *
  46 rpl_inet_ntop (int af, const void *restrict src,
  47                char *restrict dst, socklen_t cnt)
  48 {
  49   return inet_ntop (af, src, dst, cnt);
  50 }
  51
  52 #else
  53
  54 # include <stdio.h>
  55 # include <string.h>
  56 # include <errno.h>
  57
  58 # define NS_IN6ADDRSZ 16
  59 # define NS_INT16SZ 2
  60
  61 /*
  62  * WARNING: Don't even consider trying to compile this on a system where
  63  * sizeof(int) < 4.  sizeof(int) > 4 is fine; all the world's not a VAX.
  64  */
  65 typedef int verify_int_size[4 <= sizeof (int) ? 1 : -1];
  66
  67 static const char *inet_ntop4 (const unsigned char *src, char *dst, socklen_t size);
  68 # if HAVE_IPV6
  69 static const char *inet_ntop6 (const unsigned char *src, char *dst, socklen_t size);
  70 # endif
  71
  72
  73 /* char *
  74  * inet_ntop(af, src, dst, size)
  75  *      convert a network format address to presentation format.
  76  * return:
  77  *      pointer to presentation format address (`dst'), or NULL (see errno).
  78  * author:
  79  *      Paul Vixie, 1996.
  80  */
  81 const char *
  82 inet_ntop (int af, const void *restrict src,
  83            char *restrict dst, socklen_t cnt)
  84 {
  85   switch (af)
  86     {
  87 # if HAVE_IPV4
  88     case AF_INET:
  89       return (inet_ntop4 (src, dst, cnt));
  90 # endif
  91
  92 # if HAVE_IPV6
  93     case AF_INET6:
  94       return (inet_ntop6 (src, dst, cnt));
  95 # endif
  96
  97     default:
  98       errno = EAFNOSUPPORT;
  99       return (NULL);
 100     }
 101   /* NOTREACHED */
 102 }
 103
 104 /* const char *
 105  * inet_ntop4(src, dst, size)
 106  *      format an IPv4 address
 107  * return:
 108  *      `dst' (as a const)
 109  * notes:
 110  *      (1) uses no statics
 111  *      (2) takes a u_char* not an in_addr as input
 112  * author:
 113  *      Paul Vixie, 1996.
 114  */
 115 static const char *
 116 inet_ntop4 (const unsigned char *src, char *dst, socklen_t size)
 117 {
 118   char tmp[sizeof "255.255.255.255"];
 119   int len;
 120
 121   len = sprintf (tmp, "%u.%u.%u.%u", src[0], src[1], src[2], src[3]);
 122   if (len < 0)
 123     return NULL;
 124
 125   if (len > size)
 126     {
 127       errno = ENOSPC;
 128       return NULL;
 129     }
 130
 131   return strcpy (dst, tmp);
 132 }
 133
 134 # if HAVE_IPV6
 135
 136 /* const char *
 137  * inet_ntop6(src, dst, size)
 138  *      convert IPv6 binary address into presentation (printable) format
 139  * author:
 140  *      Paul Vixie, 1996.
 141  */
 142 static const char *
 143 inet_ntop6 (const unsigned char *src, char *dst, socklen_t size)
 144 {
 145   /*
 146    * Note that int32_t and int16_t need only be "at least" large enough
 147    * to contain a value of the specified size.  On some systems, like
 148    * Crays, there is no such thing as an integer variable with 16 bits.
 149    * Keep this in mind if you think this function should have been coded
 150    * to use pointer overlays.  All the world's not a VAX.
 151    */
 152   char tmp[sizeof "ffff:ffff:ffff:ffff:ffff:ffff:255.255.255.255"], *tp;
 153   struct
 154   {
 155     int base, len;
 156   } best, cur;
 157   unsigned int words[NS_IN6ADDRSZ / NS_INT16SZ];
 158   int i;
 159
 160   /*
 161    * Preprocess:
 162    *      Copy the input (bytewise) array into a wordwise array.
 163    *      Find the longest run of 0x00's in src[] for :: shorthanding.
 164    */
 165   memset (words, '\0', sizeof words);
 166   for (i = 0; i < NS_IN6ADDRSZ; i += 2)
 167     words[i / 2] = (src[i] << 8) | src[i + 1];
 168   best.base = -1;
 169   cur.base = -1;
 170   for (i = 0; i < (NS_IN6ADDRSZ / NS_INT16SZ); i++)
 171     {
 172       if (words[i] == 0)
 173         {
 174           if (cur.base == -1)
 175             cur.base = i, cur.len = 1;
 176           else
 177             cur.len++;
 178         }
 179       else
 180         {
 181           if (cur.base != -1)
 182             {
 183               if (best.base == -1 || cur.len > best.len)
 184                 best = cur;
 185               cur.base = -1;
 186             }
 187         }
 188     }
 189   if (cur.base != -1)
 190     {
 191       if (best.base == -1 || cur.len > best.len)
 192         best = cur;
 193     }
 194   if (best.base != -1 && best.len < 2)
 195     best.base = -1;
 196
 197   /*
 198    * Format the result.
 199    */
 200   tp = tmp;
 201   for (i = 0; i < (NS_IN6ADDRSZ / NS_INT16SZ); i++)
 202     {
 203       /* Are we inside the best run of 0x00's? */
 204       if (best.base != -1 && i >= best.base && i < (best.base + best.len))
 205         {
 206           if (i == best.base)
 207             *tp++ = ':';
 208           continue;
 209         }
 210       /* Are we following an initial run of 0x00s or any real hex? */
 211       if (i != 0)
 212         *tp++ = ':';
 213       /* Is this address an encapsulated IPv4? */
 214       if (i == 6 && best.base == 0 &&
 215           (best.len == 6 || (best.len == 5 && words[5] == 0xffff)))
 216         {
 217           if (!inet_ntop4 (src + 12, tp, sizeof tmp - (tp - tmp)))
 218             return (NULL);
 219           tp += strlen (tp);
 220           break;
 221         }
 222       {
 223         int len = sprintf (tp, "%x", words[i]);
 224         if (len < 0)
 225           return NULL;
 226         tp += len;
 227       }
 228     }
 229   /* Was it a trailing run of 0x00's? */
 230   if (best.base != -1 && (best.base + best.len) ==
 231       (NS_IN6ADDRSZ / NS_INT16SZ))
 232     *tp++ = ':';
 233   *tp++ = '\0';
 234
 235   /*
 236    * Check for overflow, copy, and we're done.
 237    */
 238   if ((socklen_t) (tp - tmp) > size)
 239     {
 240       errno = ENOSPC;
 241       return NULL;
 242     }
 243
 244   return strcpy (dst, tmp);
 245 }
 246
 247 # endif
 248
 249 #endif