lib/inet_ntop.c

   1 /*
   2  * Copyright (C) 1996-2001  Internet Software Consortium.
   3  *
   4  * Permission to use, copy, modify, and distribute this software for any
   5  * purpose with or without fee is hereby granted, provided that the above
   6  * copyright notice and this permission notice appear in all copies.
   7  *
   8  * THE SOFTWARE IS PROVIDED "AS IS" AND INTERNET SOFTWARE CONSORTIUM
   9  * DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL
  10  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL
  11  * INTERNET SOFTWARE CONSORTIUM BE LIABLE FOR ANY SPECIAL, DIRECT,
  12  * INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING
  13  * FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT,
  14  * NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION
  15  * WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  16  */
  17
  18
  19 #include "rsync.h"
  20
  21 #define NS_INT16SZ       2
  22 #define NS_IN6ADDRSZ    16
  23
  24 /*
  25  * WARNING: Don't even consider trying to compile this on a system where
  26  * sizeof(int) < 4.  sizeof(int) > 4 is fine; all the world's not a VAX.
  27  */
  28
  29 static const char *inet_ntop4(const unsigned char *src, char *dst,
  30                               size_t size);
  31
  32 #ifdef AF_INET6
  33 static const char *inet_ntop6(const unsigned char *src, char *dst,
  34                               size_t size);
  35 #endif
  36
  37 /* char *
  38  * isc_net_ntop(af, src, dst, size)
  39  *      convert a network format address to presentation format.
  40  * return:
  41  *      pointer to presentation format address (`dst'), or NULL (see errno).
  42  * author:
  43  *      Paul Vixie, 1996.
  44  */
  45 const char *
  46 inet_ntop(int af, const void *src, char *dst, size_t size)
  47 {
  48         switch (af) {
  49         case AF_INET:
  50                 return (inet_ntop4(src, dst, size));
  51 #ifdef AF_INET6
  52         case AF_INET6:
  53                 return (inet_ntop6(src, dst, size));
  54 #endif
  55         default:
  56                 errno = EAFNOSUPPORT;
  57                 return (NULL);
  58         }
  59         /* NOTREACHED */
  60 }
  61
  62 /* const char *
  63  * inet_ntop4(src, dst, size)
  64  *      format an IPv4 address
  65  * return:
  66  *      `dst' (as a const)
  67  * notes:
  68  *      (1) uses no statics
  69  *      (2) takes a unsigned char* not an in_addr as input
  70  * author:
  71  *      Paul Vixie, 1996.
  72  */
  73 static const char *
  74 inet_ntop4(const unsigned char *src, char *dst, size_t size)
  75 {
  76         static const char *fmt = "%u.%u.%u.%u";
  77         char tmp[sizeof "255.255.255.255"];
  78
  79         if ((size_t)sprintf(tmp, fmt, src[0], src[1], src[2], src[3]) >= size)
  80         {
  81                 errno = ENOSPC;
  82                 return (NULL);
  83         }
  84         strcpy(dst, tmp);
  85
  86         return (dst);
  87 }
  88
  89 /* const char *
  90  * isc_inet_ntop6(src, dst, size)
  91  *      convert IPv6 binary address into presentation (printable) format
  92  * author:
  93  *      Paul Vixie, 1996.
  94  */
  95 #ifdef AF_INET6
  96 static const char *
  97 inet_ntop6(const unsigned char *src, char *dst, size_t size)
  98 {
  99         /*
 100          * Note that int32_t and int16_t need only be "at least" large enough
 101          * to contain a value of the specified size.  On some systems, like
 102          * Crays, there is no such thing as an integer variable with 16 bits.
 103          * Keep this in mind if you think this function should have been coded
 104          * to use pointer overlays.  All the world's not a VAX.
 105          */
 106         char tmp[sizeof "ffff:ffff:ffff:ffff:ffff:ffff:255.255.255.255"], *tp;
 107         struct { int base, len; } best, cur;
 108         unsigned int words[NS_IN6ADDRSZ / NS_INT16SZ];
 109         int i;
 110
 111         /*
 112          * Preprocess:
 113          *      Copy the input (bytewise) array into a wordwise array.
 114          *      Find the longest run of 0x00's in src[] for :: shorthanding.
 115          */
 116         memset(words, '\0', sizeof words);
 117         for (i = 0; i < NS_IN6ADDRSZ; i++)
 118                 words[i / 2] |= (src[i] << ((1 - (i % 2)) << 3));
 119         best.base = -1;
 120         cur.base = -1;
 121         for (i = 0; i < (NS_IN6ADDRSZ / NS_INT16SZ); i++) {
 122                 if (words[i] == 0) {
 123                         if (cur.base == -1)
 124                                 cur.base = i, cur.len = 1;
 125                         else
 126                                 cur.len++;
 127                 } else {
 128                         if (cur.base != -1) {
 129                                 if (best.base == -1 || cur.len > best.len)
 130                                         best = cur;
 131                                 cur.base = -1;
 132                         }
 133                 }
 134         }
 135         if (cur.base != -1) {
 136                 if (best.base == -1 || cur.len > best.len)
 137                         best = cur;
 138         }
 139         if (best.base != -1 && best.len < 2)
 140                 best.base = -1;
 141
 142         /*
 143          * Format the result.
 144          */
 145         tp = tmp;
 146         for (i = 0; i < (NS_IN6ADDRSZ / NS_INT16SZ); i++) {
 147                 /* Are we inside the best run of 0x00's? */
 148                 if (best.base != -1 && i >= best.base &&
 149                     i < (best.base + best.len)) {
 150                         if (i == best.base)
 151                                 *tp++ = ':';
 152                         continue;
 153                 }
 154                 /* Are we following an initial run of 0x00s or any real hex? */
 155                 if (i != 0)
 156                         *tp++ = ':';
 157                 /* Is this address an encapsulated IPv4? */
 158                 if (i == 6 && best.base == 0 &&
 159                     (best.len == 6 || (best.len == 5 && words[5] == 0xffff))) {
 160                         if (!inet_ntop4(src+12, tp,
 161                                         sizeof tmp - (tp - tmp)))
 162                                 return (NULL);
 163                         tp += strlen(tp);
 164                         break;
 165                 }
 166                 tp += sprintf(tp, "%x", words[i]);
 167         }
 168         /* Was it a trailing run of 0x00's? */
 169         if (best.base != -1 && (best.base + best.len) ==
 170             (NS_IN6ADDRSZ / NS_INT16SZ))
 171                 *tp++ = ':';
 172         *tp++ = '\0';
 173
 174         /*
 175          * Check for overflow, copy, and we're done.
 176          */
 177         if ((size_t)(tp - tmp) > size) {
 178                 errno = ENOSPC;
 179                 return (NULL);
 180         }
 181         strcpy(dst, tmp);
 182         return (dst);
 183 }
 184 #endif /* AF_INET6 */