contrib/bind-9.5.2/lib/isc/inet_ntop.c

   1 /*
   2  * Copyright (C) 2004, 2005, 2007, 2009  Internet Systems Consortium, Inc. ("ISC")
   3  * Copyright (C) 1996-2001  Internet Software Consortium.
   4  *
   5  * Permission to use, copy, modify, and/or distribute this software for any
   6  * purpose with or without fee is hereby granted, provided that the above
   7  * copyright notice and this permission notice appear in all copies.
   8  *
   9  * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH
  10  * REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
  11  * AND FITNESS.  IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT,
  12  * INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
  13  * LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
  14  * OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
  15  * PERFORMANCE OF THIS SOFTWARE.
  16  */
  17
  18 /*! \file */
  19
  20 #if defined(LIBC_SCCS) && !defined(lint)
  21 static char rcsid[] =
  22         "$Id: inet_ntop.c,v 1.19.128.2 2009/07/18 23:46:53 tbox Exp $";
  23 #endif /* LIBC_SCCS and not lint */
  24
  25 #include <config.h>
  26
  27 #include <errno.h>
  28 #include <stdio.h>
  29 #include <string.h>
  30
  31 #include <isc/net.h>
  32 #include <isc/print.h>
  33
  34 #define NS_INT16SZ       2
  35 #define NS_IN6ADDRSZ    16
  36
  37 /*
  38  * WARNING: Don't even consider trying to compile this on a system where
  39  * sizeof(int) < 4.  sizeof(int) > 4 is fine; all the world's not a VAX.
  40  */
  41
  42 static const char *inet_ntop4(const unsigned char *src, char *dst,
  43                               size_t size);
  44
  45 #ifdef AF_INET6
  46 static const char *inet_ntop6(const unsigned char *src, char *dst,
  47                               size_t size);
  48 #endif
  49
  50 /*! char *
  51  * isc_net_ntop(af, src, dst, size)
  52  *      convert a network format address to presentation format.
  53  * \return
  54  *      pointer to presentation format address (`dst'), or NULL (see errno).
  55  * \author
  56  *      Paul Vixie, 1996.
  57  */
  58 const char *
  59 isc_net_ntop(int af, const void *src, char *dst, size_t size)
  60 {
  61         switch (af) {
  62         case AF_INET:
  63                 return (inet_ntop4(src, dst, size));
  64 #ifdef AF_INET6
  65         case AF_INET6:
  66                 return (inet_ntop6(src, dst, size));
  67 #endif
  68         default:
  69                 errno = EAFNOSUPPORT;
  70                 return (NULL);
  71         }
  72         /* NOTREACHED */
  73 }
  74
  75 /*! const char *
  76  * inet_ntop4(src, dst, size)
  77  *      format an IPv4 address
  78  * \return
  79  *      `dst' (as a const)
  80  * \note
  81  *      (1) uses no statics
  82  * \note
  83  *      (2) takes a unsigned char* not an in_addr as input
  84  * \author
  85  *      Paul Vixie, 1996.
  86  */
  87 static const char *
  88 inet_ntop4(const unsigned char *src, char *dst, size_t size)
  89 {
  90         static const char *fmt = "%u.%u.%u.%u";
  91         char tmp[sizeof("255.255.255.255")];
  92
  93         if ((size_t)sprintf(tmp, fmt, src[0], src[1], src[2], src[3]) >= size)
  94         {
  95                 errno = ENOSPC;
  96                 return (NULL);
  97         }
  98         strcpy(dst, tmp);
  99
 100         return (dst);
 101 }
 102
 103 /*! const char *
 104  * isc_inet_ntop6(src, dst, size)
 105  *      convert IPv6 binary address into presentation (printable) format
 106  * \author
 107  *      Paul Vixie, 1996.
 108  */
 109 #ifdef AF_INET6
 110 static const char *
 111 inet_ntop6(const unsigned char *src, char *dst, size_t size)
 112 {
 113         /*
 114          * Note that int32_t and int16_t need only be "at least" large enough
 115          * to contain a value of the specified size.  On some systems, like
 116          * Crays, there is no such thing as an integer variable with 16 bits.
 117          * Keep this in mind if you think this function should have been coded
 118          * to use pointer overlays.  All the world's not a VAX.
 119          */
 120         char tmp[sizeof("ffff:ffff:ffff:ffff:ffff:ffff:255.255.255.255")], *tp;
 121         struct { int base, len; } best, cur;
 122         unsigned int words[NS_IN6ADDRSZ / NS_INT16SZ];
 123         int i;
 124
 125         /*
 126          * Preprocess:
 127          *      Copy the input (bytewise) array into a wordwise array.
 128          *      Find the longest run of 0x00's in src[] for :: shorthanding.
 129          */
 130         memset(words, '\0', sizeof(words));
 131         for (i = 0; i < NS_IN6ADDRSZ; i++)
 132                 words[i / 2] |= (src[i] << ((1 - (i % 2)) << 3));
 133         best.base = -1;
 134         cur.base = -1;
 135         for (i = 0; i < (NS_IN6ADDRSZ / NS_INT16SZ); i++) {
 136                 if (words[i] == 0) {
 137                         if (cur.base == -1)
 138                                 cur.base = i, cur.len = 1;
 139                         else
 140                                 cur.len++;
 141                 } else {
 142                         if (cur.base != -1) {
 143                                 if (best.base == -1 || cur.len > best.len)
 144                                         best = cur;
 145                                 cur.base = -1;
 146                         }
 147                 }
 148         }
 149         if (cur.base != -1) {
 150                 if (best.base == -1 || cur.len > best.len)
 151                         best = cur;
 152         }
 153         if (best.base != -1 && best.len < 2)
 154                 best.base = -1;
 155
 156         /*
 157          * Format the result.
 158          */
 159         tp = tmp;
 160         for (i = 0; i < (NS_IN6ADDRSZ / NS_INT16SZ); i++) {
 161                 /* Are we inside the best run of 0x00's? */
 162                 if (best.base != -1 && i >= best.base &&
 163                     i < (best.base + best.len)) {
 164                         if (i == best.base)
 165                                 *tp++ = ':';
 166                         continue;
 167                 }
 168                 /* Are we following an initial run of 0x00s or any real hex? */
 169                 if (i != 0)
 170                         *tp++ = ':';
 171                 /* Is this address an encapsulated IPv4? */
 172                 if (i == 6 && best.base == 0 && (best.len == 6 ||
 173                     (best.len == 7 && words[7] != 0x0001) ||
 174                     (best.len == 5 && words[5] == 0xffff))) {
 175                         if (!inet_ntop4(src+12, tp,
 176                                         sizeof(tmp) - (tp - tmp)))
 177                                 return (NULL);
 178                         tp += strlen(tp);
 179                         break;
 180                 }
 181                 tp += sprintf(tp, "%x", words[i]);
 182         }
 183         /* Was it a trailing run of 0x00's? */
 184         if (best.base != -1 && (best.base + best.len) ==
 185             (NS_IN6ADDRSZ / NS_INT16SZ))
 186                 *tp++ = ':';
 187         *tp++ = '\0';
 188
 189         /*
 190          * Check for overflow, copy, and we're done.
 191          */
 192         if ((size_t)(tp - tmp) > size) {
 193                 errno = ENOSPC;
 194                 return (NULL);
 195         }
 196         strcpy(dst, tmp);
 197         return (dst);
 198 }
 199 #endif /* AF_INET6 */