The Tcpdump Group git mirrors - tcpdump/blob - missing/inet_ntop.c

   1 /*
   2  * Copyright (c) 1999 Kungliga Tekniska Högskolan
   3  * (Royal Institute of Technology, Stockholm, Sweden).
   4  * All rights reserved.
   5  *
   6  * Redistribution and use in source and binary forms, with or without
   7  * modification, are permitted provided that the following conditions
   8  * are met:
   9  *
  10  * 1. Redistributions of source code must retain the above copyright
  11  *    notice, this list of conditions and the following disclaimer.
  12  *
  13  * 2. Redistributions in binary form must reproduce the above copyright
  14  *    notice, this list of conditions and the following disclaimer in the
  15  *    documentation and/or other materials provided with the distribution.
  16  *
  17  * 3. All advertising materials mentioning features or use of this software
  18  *    must display the following acknowledgement:
  19  *      This product includes software developed by the Kungliga Tekniska
  20  *      Högskolan and its contributors.
  21  *
  22  * 4. Neither the name of the Institute nor the names of its contributors
  23  *    may be used to endorse or promote products derived from this software
  24  *    without specific prior written permission.
  25  *
  26  * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
  27  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  28  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  29  * ARE DISCLAIMED.  IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
  30  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  31  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  32  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  33  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  34  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  35  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  36  * SUCH DAMAGE.
  37  */
  38
  39 #include <tcpdump-stdinc.h>
  40
  41 #include <stdio.h>
  42 #include <errno.h>
  43
  44 /*
  45  *
  46  */
  47
  48 #ifndef IN6ADDRSZ
  49 #define IN6ADDRSZ   16   /* IPv6 T_AAAA */
  50 #endif
  51
  52 #ifndef INT16SZ
  53 #define INT16SZ     2    /* word size */
  54 #endif
  55
  56 static const char *
  57 inet_ntop_v4 (const void *src, char *dst, size_t size)
  58 {
  59     const char digits[] = "0123456789";
  60     int i;
  61     struct in_addr *addr = (struct in_addr *)src;
  62     u_long a = ntohl(addr->s_addr);
  63     const char *orig_dst = dst;
  64
  65     if (size < INET_ADDRSTRLEN) {
  66         errno = ENOSPC;
  67         return NULL;
  68     }
  69     for (i = 0; i < 4; ++i) {
  70         int n = (a >> (24 - i * 8)) & 0xFF;
  71         int non_zerop = 0;
  72
  73         if (non_zerop || n / 100 > 0) {
  74             *dst++ = digits[n / 100];
  75             n %= 100;
  76             non_zerop = 1;
  77         }
  78         if (non_zerop || n / 10 > 0) {
  79             *dst++ = digits[n / 10];
  80             n %= 10;
  81             non_zerop = 1;
  82         }
  83         *dst++ = digits[n];
  84         if (i != 3)
  85             *dst++ = '.';
  86     }
  87     *dst++ = '\0';
  88     return orig_dst;
  89 }
  90
  91 #ifdef INET6
  92 /*
  93  * Convert IPv6 binary address into presentation (printable) format.
  94  */
  95 static const char *
  96 inet_ntop_v6 (const u_char *src, char *dst, size_t size)
  97 {
  98   /*
  99    * Note that int32_t and int16_t need only be "at least" large enough
 100    * to contain a value of the specified size.  On some systems, like
 101    * Crays, there is no such thing as an integer variable with 16 bits.
 102    * Keep this in mind if you think this function should have been coded
 103    * to use pointer overlays.  All the world's not a VAX.
 104    */
 105   char  tmp [INET6_ADDRSTRLEN+1];
 106   char *tp;
 107   struct {
 108     long base;
 109     long len;
 110   } best, cur;
 111   u_long words [IN6ADDRSZ / INT16SZ];
 112   int    i;
 113
 114   /* Preprocess:
 115    *  Copy the input (bytewise) array into a wordwise array.
 116    *  Find the longest run of 0x00's in src[] for :: shorthanding.
 117    */
 118   memset (words, 0, sizeof(words));
 119   for (i = 0; i < IN6ADDRSZ; i++)
 120       words[i/2] |= (src[i] << ((1 - (i % 2)) << 3));
 121
 122   best.base = -1;
 123   cur.base  = -1;
 124   for (i = 0; i < (IN6ADDRSZ / INT16SZ); i++)
 125   {
 126     if (words[i] == 0)
 127     {
 128       if (cur.base == -1)
 129            cur.base = i, cur.len = 1;
 130       else cur.len++;
 131     }
 132     else if (cur.base != -1)
 133     {
 134       if (best.base == -1 || cur.len > best.len)
 135          best = cur;
 136       cur.base = -1;
 137     }
 138   }
 139   if ((cur.base != -1) && (best.base == -1 || cur.len > best.len))
 140      best = cur;
 141   if (best.base != -1 && best.len < 2)
 142      best.base = -1;
 143
 144   /* Format the result.
 145    */
 146   tp = tmp;
 147   for (i = 0; i < (IN6ADDRSZ / INT16SZ); i++)
 148   {
 149     /* Are we inside the best run of 0x00's?
 150      */
 151     if (best.base != -1 && i >= best.base && i < (best.base + best.len))
 152     {
 153       if (i == best.base)
 154          *tp++ = ':';
 155       continue;
 156     }
 157
 158     /* Are we following an initial run of 0x00s or any real hex?
 159      */
 160     if (i != 0)
 161        *tp++ = ':';
 162
 163     /* Is this address an encapsulated IPv4?
 164      */
 165     if (i == 6 && best.base == 0 &&
 166         (best.len == 6 || (best.len == 5 && words[5] == 0xffff)))
 167     {
 168       if (!inet_ntop_v4(src+12, tp, sizeof(tmp) - (tp - tmp)))
 169       {
 170         errno = ENOSPC;
 171         return (NULL);
 172       }
 173       tp += strlen(tp);
 174       break;
 175     }
 176     tp += sprintf (tp, "%lX", words[i]);
 177   }
 178
 179   /* Was it a trailing run of 0x00's?
 180    */
 181   if (best.base != -1 && (best.base + best.len) == (IN6ADDRSZ / INT16SZ))
 182      *tp++ = ':';
 183   *tp++ = '\0';
 184
 185   /* Check for overflow, copy, and we're done.
 186    */
 187   if ((size_t)(tp - tmp) > size)
 188   {
 189     errno = ENOSPC;
 190     return (NULL);
 191   }
 192   return strcpy (dst, tmp);
 193 }
 194 #endif   /* INET6 */
 195
 196
 197 const char *
 198 inet_ntop(int af, const void *src, char *dst, size_t size)
 199 {
 200     switch (af) {
 201     case AF_INET :
 202         return inet_ntop_v4 (src, dst, size);
 203 #ifdef INET6
 204     case AF_INET6:
 205          return inet_ntop_v6 ((const u_char*)src, dst, size);
 206 #endif
 207     default :
 208         errno = EAFNOSUPPORT;
 209         return NULL;
 210     }
 211 }