lib/libc/inet/inet_ntop.c

   1 /*      $NetBSD: inet_ntop.c,v 1.1.1.4 2009/04/12 16:35:45 christos Exp $       */
   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 #include <sys/cdefs.h>
  21 #if defined(LIBC_SCCS) && !defined(lint)
  22 #if 0
  23 static const char rcsid[] = "Id: inet_ntop.c,v 1.5 2005/11/03 22:59:52 marka Exp";
  24 #else
  25 __RCSID("$NetBSD: inet_ntop.c,v 1.7 2008/09/11 15:40:43 christos Exp $");
  26 #endif
  27 #endif /* LIBC_SCCS and not lint */
  28
  29 #include "port_before.h"
  30
  31 #include "namespace.h"
  32 #include <sys/param.h>
  33 #include <sys/types.h>
  34 #include <sys/socket.h>
  35
  36 #include <netinet/in.h>
  37 #include <arpa/inet.h>
  38 #include <arpa/nameser.h>
  39
  40 #include <assert.h>
  41 #include <errno.h>
  42 #include <stdio.h>
  43 #include <stdlib.h>
  44 #include <string.h>
  45
  46 #include "port_after.h"
  47
  48 #ifdef __weak_alias
  49 __weak_alias(inet_ntop,_inet_ntop)
  50 #endif
  51
  52 /*%
  53  * WARNING: Don't even consider trying to compile this on a system where
  54  * sizeof(int) < 4.  sizeof(int) > 4 is fine; all the world's not a VAX.
  55  */
  56
  57 static const char *inet_ntop4(const u_char *src, char *dst, socklen_t size);
  58 static const char *inet_ntop6(const u_char *src, char *dst, socklen_t size);
  59
  60 /* char *
  61  * inet_ntop(af, src, dst, size)
  62  *      convert a network format address to presentation format.
  63  * return:
  64  *      pointer to presentation format address (`dst'), or NULL (see errno).
  65  * author:
  66  *      Paul Vixie, 1996.
  67  */
  68 const char *
  69 inet_ntop(af, src, dst, size)
  70         int af;
  71         const void *src;
  72         char *dst;
  73         socklen_t size;
  74 {
  75
  76         _DIAGASSERT(src != NULL);
  77         _DIAGASSERT(dst != NULL);
  78
  79         switch (af) {
  80         case AF_INET:
  81                 return (inet_ntop4(src, dst, size));
  82         case AF_INET6:
  83                 return (inet_ntop6(src, dst, size));
  84         default:
  85                 errno = EAFNOSUPPORT;
  86                 return (NULL);
  87         }
  88         /* NOTREACHED */
  89 }
  90
  91 /* const char *
  92  * inet_ntop4(src, dst, size)
  93  *      format an IPv4 address, more or less like inet_ntoa()
  94  * return:
  95  *      `dst' (as a const)
  96  * notes:
  97  *      (1) uses no statics
  98  *      (2) takes a u_char* not an in_addr as input
  99  * author:
 100  *      Paul Vixie, 1996.
 101  */
 102 static const char *
 103 inet_ntop4(src, dst, size)
 104         const u_char *src;
 105         char *dst;
 106         socklen_t size;
 107 {
 108         char tmp[sizeof "255.255.255.255"];
 109         int l;
 110
 111         _DIAGASSERT(src != NULL);
 112         _DIAGASSERT(dst != NULL);
 113
 114         l = snprintf(tmp, sizeof(tmp), "%u.%u.%u.%u",
 115             src[0], src[1], src[2], src[3]);
 116         if (l <= 0 || (socklen_t) l >= size) {
 117                 errno = ENOSPC;
 118                 return (NULL);
 119         }
 120         strlcpy(dst, tmp, size);
 121         return (dst);
 122 }
 123
 124 /* const char *
 125  * inet_ntop6(src, dst, size)
 126  *      convert IPv6 binary address into presentation (printable) format
 127  * author:
 128  *      Paul Vixie, 1996.
 129  */
 130 static const char *
 131 inet_ntop6(src, dst, size)
 132         const u_char *src;
 133         char *dst;
 134         socklen_t size;
 135 {
 136         /*
 137          * Note that int32_t and int16_t need only be "at least" large enough
 138          * to contain a value of the specified size.  On some systems, like
 139          * Crays, there is no such thing as an integer variable with 16 bits.
 140          * Keep this in mind if you think this function should have been coded
 141          * to use pointer overlays.  All the world's not a VAX.
 142          */
 143         char tmp[sizeof "ffff:ffff:ffff:ffff:ffff:ffff:255.255.255.255"];
 144         char *tp, *ep;
 145         struct { int base, len; } best, cur;
 146         u_int words[NS_IN6ADDRSZ / NS_INT16SZ];
 147         int i;
 148         int advance;
 149
 150         _DIAGASSERT(src != NULL);
 151         _DIAGASSERT(dst != NULL);
 152
 153         /*
 154          * Preprocess:
 155          *      Copy the input (bytewise) array into a wordwise array.
 156          *      Find the longest run of 0x00's in src[] for :: shorthanding.
 157          */
 158         memset(words, '\0', sizeof words);
 159         for (i = 0; i < NS_IN6ADDRSZ; i++)
 160                 words[i / 2] |= (src[i] << ((1 - (i % 2)) << 3));
 161         best.base = -1;
 162         best.len = 0;
 163         cur.base = -1;
 164         cur.len = 0;
 165         for (i = 0; i < (NS_IN6ADDRSZ / NS_INT16SZ); i++) {
 166                 if (words[i] == 0) {
 167                         if (cur.base == -1)
 168                                 cur.base = i, cur.len = 1;
 169                         else
 170                                 cur.len++;
 171                 } else {
 172                         if (cur.base != -1) {
 173                                 if (best.base == -1 || cur.len > best.len)
 174                                         best = cur;
 175                                 cur.base = -1;
 176                         }
 177                 }
 178         }
 179         if (cur.base != -1) {
 180                 if (best.base == -1 || cur.len > best.len)
 181                         best = cur;
 182         }
 183         if (best.base != -1 && best.len < 2)
 184                 best.base = -1;
 185
 186         /*
 187          * Format the result.
 188          */
 189         tp = tmp;
 190         ep = tmp + sizeof(tmp);
 191         for (i = 0; i < (NS_IN6ADDRSZ / NS_INT16SZ); i++) {
 192                 /* Are we inside the best run of 0x00's? */
 193                 if (best.base != -1 && i >= best.base &&
 194                     i < (best.base + best.len)) {
 195                         if (i == best.base)
 196                                 *tp++ = ':';
 197                         continue;
 198                 }
 199                 /* Are we following an initial run of 0x00s or any real hex? */
 200                 if (i != 0) {
 201                         if (tp + 1 >= ep)
 202                                 return (NULL);
 203                         *tp++ = ':';
 204                 }
 205                 /* Is this address an encapsulated IPv4? */
 206                 if (i == 6 && best.base == 0 &&
 207                     (best.len == 6 ||
 208                     (best.len == 7 && words[7] != 0x0001) ||
 209                     (best.len == 5 && words[5] == 0xffff))) {
 210                         if (!inet_ntop4(src+12, tp, (socklen_t)(ep - tp)))
 211                                 return (NULL);
 212                         tp += strlen(tp);
 213                         break;
 214                 }
 215                 advance = snprintf(tp, (size_t)(ep - tp), "%x", words[i]);
 216                 if (advance <= 0 || advance >= ep - tp)
 217                         return (NULL);
 218                 tp += advance;
 219         }
 220         /* Was it a trailing run of 0x00's? */
 221         if (best.base != -1 && (best.base + best.len) ==
 222             (NS_IN6ADDRSZ / NS_INT16SZ)) {
 223                 if (tp + 1 >= ep)
 224                         return (NULL);
 225                 *tp++ = ':';
 226         }
 227         if (tp + 1 >= ep)
 228                 return (NULL);
 229         *tp++ = '\0';
 230
 231         /*
 232          * Check for overflow, copy, and we're done.
 233          */
 234         if ((size_t)(tp - tmp) > size) {
 235                 errno = ENOSPC;
 236                 return (NULL);
 237         }
 238         strlcpy(dst, tmp, size);
 239         return (dst);
 240 }
 241
 242 /*! \file */