external/bsd/libbind/dist/inet/inet_ntop.c

   1 /*      $NetBSD$        */
   2
   3 /*
   4  * Copyright (c) 2004 by Internet Systems Consortium, Inc. ("ISC")
   5  * Copyright (c) 1996-1999 by Internet Software Consortium.
   6  *
   7  * Permission to use, copy, modify, and 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
  12  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
  13  * MERCHANTABILITY AND FITNESS.  IN NO EVENT SHALL ISC BE LIABLE FOR
  14  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
  15  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
  16  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT
  17  * OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  18  */
  19
  20 #if defined(LIBC_SCCS) && !defined(lint)
  21 static const char rcsid[] = "Id: inet_ntop.c,v 1.5 2005/11/03 22:59:52 marka Exp";
  22 #endif /* LIBC_SCCS and not lint */
  23
  24 #include "port_before.h"
  25
  26 #include <sys/param.h>
  27 #include <sys/types.h>
  28 #include <sys/socket.h>
  29
  30 #include <netinet/in.h>
  31 #include <arpa/inet.h>
  32 #include <arpa/nameser.h>
  33
  34 #include <errno.h>
  35 #include <stdio.h>
  36 #include <string.h>
  37
  38 #include "port_after.h"
  39
  40 #ifdef SPRINTF_CHAR
  41 # define SPRINTF(x) strlen(sprintf/**/x)
  42 #else
  43 # define SPRINTF(x) ((size_t)sprintf x)
  44 #endif
  45
  46 /*%
  47  * WARNING: Don't even consider trying to compile this on a system where
  48  * sizeof(int) < 4.  sizeof(int) > 4 is fine; all the world's not a VAX.
  49  */
  50
  51 static const char *inet_ntop4 __P((const u_char *src, char *dst, size_t size));
  52 static const char *inet_ntop6 __P((const u_char *src, char *dst, size_t size));
  53
  54 /* char *
  55  * inet_ntop(af, src, dst, size)
  56  *      convert a network format address to presentation format.
  57  * return:
  58  *      pointer to presentation format address (`dst'), or NULL (see errno).
  59  * author:
  60  *      Paul Vixie, 1996.
  61  */
  62 const char *
  63 inet_ntop(af, src, dst, size)
  64         int af;
  65         const void *src;
  66         char *dst;
  67         size_t size;
  68 {
  69         switch (af) {
  70         case AF_INET:
  71                 return (inet_ntop4(src, dst, size));
  72         case AF_INET6:
  73                 return (inet_ntop6(src, dst, size));
  74         default:
  75                 errno = EAFNOSUPPORT;
  76                 return (NULL);
  77         }
  78         /* NOTREACHED */
  79 }
  80
  81 /* const char *
  82  * inet_ntop4(src, dst, size)
  83  *      format an IPv4 address
  84  * return:
  85  *      `dst' (as a const)
  86  * notes:
  87  *      (1) uses no statics
  88  *      (2) takes a u_char* not an in_addr as input
  89  * author:
  90  *      Paul Vixie, 1996.
  91  */
  92 static const char *
  93 inet_ntop4(src, dst, size)
  94         const u_char *src;
  95         char *dst;
  96         size_t size;
  97 {
  98         static const char fmt[] = "%u.%u.%u.%u";
  99         char tmp[sizeof "255.255.255.255"];
 100
 101         if (SPRINTF((tmp, fmt, src[0], src[1], src[2], src[3])) >= size) {
 102                 errno = ENOSPC;
 103                 return (NULL);
 104         }
 105         strcpy(dst, tmp);
 106         return (dst);
 107 }
 108
 109 /* const char *
 110  * inet_ntop6(src, dst, size)
 111  *      convert IPv6 binary address into presentation (printable) format
 112  * author:
 113  *      Paul Vixie, 1996.
 114  */
 115 static const char *
 116 inet_ntop6(src, dst, size)
 117         const u_char *src;
 118         char *dst;
 119         size_t size;
 120 {
 121         /*
 122          * Note that int32_t and int16_t need only be "at least" large enough
 123          * to contain a value of the specified size.  On some systems, like
 124          * Crays, there is no such thing as an integer variable with 16 bits.
 125          * Keep this in mind if you think this function should have been coded
 126          * to use pointer overlays.  All the world's not a VAX.
 127          */
 128         char tmp[sizeof "ffff:ffff:ffff:ffff:ffff:ffff:255.255.255.255"], *tp;
 129         struct { int base, len; } best, cur;
 130         u_int words[NS_IN6ADDRSZ / NS_INT16SZ];
 131         int i;
 132
 133         /*
 134          * Preprocess:
 135          *      Copy the input (bytewise) array into a wordwise array.
 136          *      Find the longest run of 0x00's in src[] for :: shorthanding.
 137          */
 138         memset(words, '\0', sizeof words);
 139         for (i = 0; i < NS_IN6ADDRSZ; i++)
 140                 words[i / 2] |= (src[i] << ((1 - (i % 2)) << 3));
 141         best.base = -1;
 142         best.len = 0;
 143         cur.base = -1;
 144         cur.len = 0;
 145         for (i = 0; i < (NS_IN6ADDRSZ / NS_INT16SZ); i++) {
 146                 if (words[i] == 0) {
 147                         if (cur.base == -1)
 148                                 cur.base = i, cur.len = 1;
 149                         else
 150                                 cur.len++;
 151                 } else {
 152                         if (cur.base != -1) {
 153                                 if (best.base == -1 || cur.len > best.len)
 154                                         best = cur;
 155                                 cur.base = -1;
 156                         }
 157                 }
 158         }
 159         if (cur.base != -1) {
 160                 if (best.base == -1 || cur.len > best.len)
 161                         best = cur;
 162         }
 163         if (best.base != -1 && best.len < 2)
 164                 best.base = -1;
 165
 166         /*
 167          * Format the result.
 168          */
 169         tp = tmp;
 170         for (i = 0; i < (NS_IN6ADDRSZ / NS_INT16SZ); i++) {
 171                 /* Are we inside the best run of 0x00's? */
 172                 if (best.base != -1 && i >= best.base &&
 173                     i < (best.base + best.len)) {
 174                         if (i == best.base)
 175                                 *tp++ = ':';
 176                         continue;
 177                 }
 178                 /* Are we following an initial run of 0x00s or any real hex? */
 179                 if (i != 0)
 180                         *tp++ = ':';
 181                 /* Is this address an encapsulated IPv4? */
 182                 if (i == 6 && best.base == 0 && (best.len == 6 ||
 183                     (best.len == 7 && words[7] != 0x0001) ||
 184                     (best.len == 5 && words[5] == 0xffff))) {
 185                         if (!inet_ntop4(src+12, tp, sizeof tmp - (tp - tmp)))
 186                                 return (NULL);
 187                         tp += strlen(tp);
 188                         break;
 189                 }
 190                 tp += SPRINTF((tp, "%x", words[i]));
 191         }
 192         /* Was it a trailing run of 0x00's? */
 193         if (best.base != -1 && (best.base + best.len) ==
 194             (NS_IN6ADDRSZ / NS_INT16SZ))
 195                 *tp++ = ':';
 196         *tp++ = '\0';
 197
 198         /*
 199          * Check for overflow, copy, and we're done.
 200          */
 201         if ((size_t)(tp - tmp) > size) {
 202                 errno = ENOSPC;
 203                 return (NULL);
 204         }
 205         strcpy(dst, tmp);
 206         return (dst);
 207 }
 208
 209 /*! \file */