external/bsd/bind/dist/lib/isc/inet_ntop.c

   1 /*      $NetBSD: inet_ntop.c,v 1.4 2014/12/10 04:37:59 christos Exp $   */
   2
   3 /*
   4  * Copyright (C) 2004, 2005, 2007, 2009  Internet Systems Consortium, Inc. ("ISC")
   5  * Copyright (C) 1996-2001  Internet Software Consortium.
   6  *
   7  * Permission to use, copy, modify, and/or distribute this software for any
   8  * purpose with or without fee is hereby granted, provided that the above
   9  * copyright notice and this permission notice appear in all copies.
  10  *
  11  * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH
  12  * REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
  13  * AND FITNESS.  IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT,
  14  * INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
  15  * LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
  16  * OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
  17  * PERFORMANCE OF THIS SOFTWARE.
  18  */
  19
  20 /*! \file */
  21
  22 #if defined(LIBC_SCCS) && !defined(lint)
  23 static char rcsid[] =
  24         "Id: inet_ntop.c,v 1.21 2009/07/17 23:47:41 tbox Exp ";
  25 #endif /* LIBC_SCCS and not lint */
  26
  27 #include <config.h>
  28
  29 #include <errno.h>
  30 #include <stdio.h>
  31 #include <string.h>
  32
  33 #include <isc/net.h>
  34 #include <isc/print.h>
  35
  36 #define NS_INT16SZ       2
  37 #define NS_IN6ADDRSZ    16
  38
  39 /*
  40  * WARNING: Don't even consider trying to compile this on a system where
  41  * sizeof(int) < 4.  sizeof(int) > 4 is fine; all the world's not a VAX.
  42  */
  43
  44 static const char *inet_ntop4(const unsigned char *src, char *dst,
  45                               size_t size);
  46
  47 #ifdef AF_INET6
  48 static const char *inet_ntop6(const unsigned char *src, char *dst,
  49                               size_t size);
  50 #endif
  51
  52 /*! char *
  53  * isc_net_ntop(af, src, dst, size)
  54  *      convert a network format address to presentation format.
  55  * \return
  56  *      pointer to presentation format address (`dst'), or NULL (see errno).
  57  * \author
  58  *      Paul Vixie, 1996.
  59  */
  60 const char *
  61 isc_net_ntop(int af, const void *src, char *dst, size_t size)
  62 {
  63         switch (af) {
  64         case AF_INET:
  65                 return (inet_ntop4(src, dst, size));
  66 #ifdef AF_INET6
  67         case AF_INET6:
  68                 return (inet_ntop6(src, dst, size));
  69 #endif
  70         default:
  71                 errno = EAFNOSUPPORT;
  72                 return (NULL);
  73         }
  74         /* NOTREACHED */
  75 }
  76
  77 /*! const char *
  78  * inet_ntop4(src, dst, size)
  79  *      format an IPv4 address
  80  * \return
  81  *      `dst' (as a const)
  82  * \note
  83  *      (1) uses no statics
  84  * \note
  85  *      (2) takes a unsigned char* not an in_addr as input
  86  * \author
  87  *      Paul Vixie, 1996.
  88  */
  89 static const char *
  90 inet_ntop4(const unsigned char *src, char *dst, size_t size)
  91 {
  92         static const char *fmt = "%u.%u.%u.%u";
  93         char tmp[sizeof("255.255.255.255")];
  94
  95         if ((size_t)sprintf(tmp, fmt, src[0], src[1], src[2], src[3]) >= size)
  96         {
  97                 errno = ENOSPC;
  98                 return (NULL);
  99         }
 100         strcpy(dst, tmp);
 101
 102         return (dst);
 103 }
 104
 105 /*! const char *
 106  * isc_inet_ntop6(src, dst, size)
 107  *      convert IPv6 binary address into presentation (printable) format
 108  * \author
 109  *      Paul Vixie, 1996.
 110  */
 111 #ifdef AF_INET6
 112 static const char *
 113 inet_ntop6(const unsigned char *src, char *dst, size_t size)
 114 {
 115         /*
 116          * Note that int32_t and int16_t need only be "at least" large enough
 117          * to contain a value of the specified size.  On some systems, like
 118          * Crays, there is no such thing as an integer variable with 16 bits.
 119          * Keep this in mind if you think this function should have been coded
 120          * to use pointer overlays.  All the world's not a VAX.
 121          */
 122         char tmp[sizeof("ffff:ffff:ffff:ffff:ffff:ffff:255.255.255.255")], *tp;
 123         struct { int base, len; } best, cur;
 124         unsigned int words[NS_IN6ADDRSZ / NS_INT16SZ];
 125         int i;
 126
 127         /*
 128          * Preprocess:
 129          *      Copy the input (bytewise) array into a wordwise array.
 130          *      Find the longest run of 0x00's in src[] for :: shorthanding.
 131          */
 132         memset(words, '\0', sizeof(words));
 133         for (i = 0; i < NS_IN6ADDRSZ; i++)
 134                 words[i / 2] |= (src[i] << ((1 - (i % 2)) << 3));
 135         best.base = -1;
 136         cur.base = -1;
 137         for (i = 0; i < (NS_IN6ADDRSZ / NS_INT16SZ); i++) {
 138                 if (words[i] == 0) {
 139                         if (cur.base == -1)
 140                                 cur.base = i, cur.len = 1;
 141                         else
 142                                 cur.len++;
 143                 } else {
 144                         if (cur.base != -1) {
 145                                 if (best.base == -1 || cur.len > best.len)
 146                                         best = cur;
 147                                 cur.base = -1;
 148                         }
 149                 }
 150         }
 151         if (cur.base != -1) {
 152                 if (best.base == -1 || cur.len > best.len)
 153                         best = cur;
 154         }
 155         if (best.base != -1 && best.len < 2)
 156                 best.base = -1;
 157
 158         /*
 159          * Format the result.
 160          */
 161         tp = tmp;
 162         for (i = 0; i < (NS_IN6ADDRSZ / NS_INT16SZ); i++) {
 163                 /* Are we inside the best run of 0x00's? */
 164                 if (best.base != -1 && i >= best.base &&
 165                     i < (best.base + best.len)) {
 166                         if (i == best.base)
 167                                 *tp++ = ':';
 168                         continue;
 169                 }
 170                 /* Are we following an initial run of 0x00s or any real hex? */
 171                 if (i != 0)
 172                         *tp++ = ':';
 173                 /* Is this address an encapsulated IPv4? */
 174                 if (i == 6 && best.base == 0 && (best.len == 6 ||
 175                     (best.len == 7 && words[7] != 0x0001) ||
 176                     (best.len == 5 && words[5] == 0xffff))) {
 177                         if (!inet_ntop4(src+12, tp,
 178                                         sizeof(tmp) - (tp - tmp)))
 179                                 return (NULL);
 180                         tp += strlen(tp);
 181                         break;
 182                 }
 183                 tp += sprintf(tp, "%x", words[i]);
 184         }
 185         /* Was it a trailing run of 0x00's? */
 186         if (best.base != -1 && (best.base + best.len) ==
 187             (NS_IN6ADDRSZ / NS_INT16SZ))
 188                 *tp++ = ':';
 189         *tp++ = '\0';
 190
 191         /*
 192          * Check for overflow, copy, and we're done.
 193          */
 194         if ((size_t)(tp - tmp) > size) {
 195                 errno = ENOSPC;
 196                 return (NULL);
 197         }
 198         strcpy(dst, tmp);
 199         return (dst);
 200 }
 201 #endif /* AF_INET6 */