The Tcpdump Group git mirrors - tcpdump/blob - addrtostr.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 #ifdef HAVE_CONFIG_H
  40 #include <config.h>
  41 #endif
  42
  43 #include "netdissect-stdinc.h"
  44 #include "addrtostr.h"
  45
  46 #include <stdio.h>
  47 #include <string.h>
  48
  49 /*
  50  *
  51  */
  52
  53 #ifndef IN6ADDRSZ
  54 #define IN6ADDRSZ   16   /* IPv6 T_AAAA */
  55 #endif
  56
  57 #ifndef INT16SZ
  58 #define INT16SZ     2    /* word size */
  59 #endif
  60
  61 const char *
  62 addrtostr (const void *src, char *dst, size_t size)
  63 {
  64     const u_char *srcaddr = (const u_char *)src;
  65     const char digits[] = "0123456789";
  66     int i;
  67     const char *orig_dst = dst;
  68
  69     if (size < INET_ADDRSTRLEN) {
  70         errno = ENOSPC;
  71         return NULL;
  72     }
  73     for (i = 0; i < 4; ++i) {
  74         int n = *srcaddr++;
  75         int non_zerop = 0;
  76
  77         if (non_zerop || n / 100 > 0) {
  78             *dst++ = digits[n / 100];
  79             n %= 100;
  80             non_zerop = 1;
  81         }
  82         if (non_zerop || n / 10 > 0) {
  83             *dst++ = digits[n / 10];
  84             n %= 10;
  85             non_zerop = 1;
  86         }
  87         *dst++ = digits[n];
  88         if (i != 3)
  89             *dst++ = '.';
  90     }
  91     *dst++ = '\0';
  92     return orig_dst;
  93 }
  94
  95 /*
  96  * Convert IPv6 binary address into presentation (printable) format.
  97  */
  98 const char *
  99 addrtostr6 (const void *src, char *dst, size_t size)
 100 {
 101   /*
 102    * Note that int32_t and int16_t need only be "at least" large enough
 103    * to contain a value of the specified size.  On some systems, like
 104    * Crays, there is no such thing as an integer variable with 16 bits.
 105    * Keep this in mind if you think this function should have been coded
 106    * to use pointer overlays.  All the world's not a VAX.
 107    */
 108   const u_char *srcaddr = (const u_char *)src;
 109   char *dp;
 110   size_t space_left, added_space;
 111   int snprintfed;
 112   struct {
 113     int base;
 114     int len;
 115   } best, cur;
 116   uint16_t words [IN6ADDRSZ / INT16SZ];
 117   int  i;
 118
 119   /* Preprocess:
 120    *  Copy the input (bytewise) array into a wordwise array.
 121    *  Find the longest run of 0x00's in src[] for :: shorthanding.
 122    */
 123   for (i = 0; i < (IN6ADDRSZ / INT16SZ); i++)
 124       words[i] = (srcaddr[2*i] << 8) | srcaddr[2*i + 1];
 125
 126   best.len = 0;
 127   best.base = -1;
 128   cur.len = 0;
 129   cur.base  = -1;
 130   for (i = 0; i < (IN6ADDRSZ / INT16SZ); i++)
 131   {
 132     if (words[i] == 0)
 133     {
 134       if (cur.base == -1)
 135            cur.base = i, cur.len = 1;
 136       else cur.len++;
 137     }
 138     else if (cur.base != -1)
 139     {
 140       if (best.base == -1 || cur.len > best.len)
 141          best = cur;
 142       cur.base = -1;
 143     }
 144   }
 145   if ((cur.base != -1) && (best.base == -1 || cur.len > best.len))
 146      best = cur;
 147   if (best.base != -1 && best.len < 2)
 148      best.base = -1;
 149
 150   /* Format the result.
 151    */
 152   dp = dst;
 153   space_left = size;
 154 #define APPEND_CHAR(c) \
 155     { \
 156         if (space_left == 0) { \
 157             errno = ENOSPC; \
 158             return (NULL); \
 159         } \
 160         *dp++ = c; \
 161         space_left--; \
 162     }
 163   for (i = 0; i < (IN6ADDRSZ / INT16SZ); i++)
 164   {
 165     /* Are we inside the best run of 0x00's?
 166      */
 167     if (best.base != -1 && i >= best.base && i < (best.base + best.len))
 168     {
 169       if (i == best.base)
 170          APPEND_CHAR(':');
 171       continue;
 172     }
 173
 174     /* Are we following an initial run of 0x00s or any real hex?
 175      */
 176     if (i != 0)
 177        APPEND_CHAR(':');
 178
 179     /* Is this address an encapsulated IPv4?
 180      */
 181     if (i == 6 && best.base == 0 &&
 182         (best.len == 6 || (best.len == 5 && words[5] == 0xffff)))
 183     {
 184       if (!addrtostr(srcaddr+12, dp, space_left))
 185       {
 186         errno = ENOSPC;
 187         return (NULL);
 188       }
 189       added_space = strlen(dp);
 190       dp += added_space;
 191       space_left -= added_space;
 192       break;
 193     }
 194     snprintfed = snprintf (dp, space_left, "%x", words[i]);
 195     if (snprintfed < 0)
 196         return (NULL);
 197     if ((size_t) snprintfed >= space_left)
 198     {
 199         errno = ENOSPC;
 200         return (NULL);
 201     }
 202     dp += snprintfed;
 203     space_left -= snprintfed;
 204   }
 205
 206   /* Was it a trailing run of 0x00's?
 207    */
 208   if (best.base != -1 && (best.base + best.len) == (IN6ADDRSZ / INT16SZ))
 209      APPEND_CHAR(':');
 210   APPEND_CHAR('\0');
 211
 212   return (dst);
 213 }