lib/libc/inet/inet_ntop.c

   1 /*      $NetBSD: inet_ntop.c,v 1.9 2012/03/20 17:08:13 matt 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 1.9 2012/03/20 17:08:13 matt 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(int af, const void *src, char *dst, socklen_t size)
  70 {
  71
  72         _DIAGASSERT(src != NULL);
  73         _DIAGASSERT(dst != NULL);
  74
  75         switch (af) {
  76         case AF_INET:
  77                 return (inet_ntop4(src, dst, size));
  78         case AF_INET6:
  79                 return (inet_ntop6(src, dst, size));
  80         default:
  81                 errno = EAFNOSUPPORT;
  82                 return (NULL);
  83         }
  84         /* NOTREACHED */
  85 }
  86
  87 /* const char *
  88  * inet_ntop4(src, dst, size)
  89  *      format an IPv4 address, more or less like inet_ntoa()
  90  * return:
  91  *      `dst' (as a const)
  92  * notes:
  93  *      (1) uses no statics
  94  *      (2) takes a u_char* not an in_addr as input
  95  * author:
  96  *      Paul Vixie, 1996.
  97  */
  98 static const char *
  99 inet_ntop4(const u_char *src, char *dst, socklen_t size)
 100 {
 101         char tmp[sizeof "255.255.255.255"];
 102         int l;
 103
 104         _DIAGASSERT(src != NULL);
 105         _DIAGASSERT(dst != NULL);
 106
 107         l = snprintf(tmp, sizeof(tmp), "%u.%u.%u.%u",
 108             src[0], src[1], src[2], src[3]);
 109         if (l <= 0 || (socklen_t) l >= size) {
 110                 errno = ENOSPC;
 111                 return (NULL);
 112         }
 113         strlcpy(dst, tmp, size);
 114         return (dst);
 115 }
 116
 117 /* const char *
 118  * inet_ntop6(src, dst, size)
 119  *      convert IPv6 binary address into presentation (printable) format
 120  * author:
 121  *      Paul Vixie, 1996.
 122  */
 123 static const char *
 124 inet_ntop6(const u_char *src, char *dst, socklen_t size)
 125 {
 126         /*
 127          * Note that int32_t and int16_t need only be "at least" large enough
 128          * to contain a value of the specified size.  On some systems, like
 129          * Crays, there is no such thing as an integer variable with 16 bits.
 130          * Keep this in mind if you think this function should have been coded
 131          * to use pointer overlays.  All the world's not a VAX.
 132          */
 133         char tmp[sizeof "ffff:ffff:ffff:ffff:ffff:ffff:255.255.255.255"];
 134         char *tp, *ep;
 135         struct { int base, len; } best, cur;
 136         u_int words[NS_IN6ADDRSZ / NS_INT16SZ];
 137         int i;
 138         int advance;
 139
 140         _DIAGASSERT(src != NULL);
 141         _DIAGASSERT(dst != NULL);
 142
 143         /*
 144          * Preprocess:
 145          *      Copy the input (bytewise) array into a wordwise array.
 146          *      Find the longest run of 0x00's in src[] for :: shorthanding.
 147          */
 148         memset(words, '\0', sizeof words);
 149         for (i = 0; i < NS_IN6ADDRSZ; i++)
 150                 words[i / 2] |= (src[i] << ((1 - (i % 2)) << 3));
 151         best.base = -1;
 152         best.len = 0;
 153         cur.base = -1;
 154         cur.len = 0;
 155         for (i = 0; i < (NS_IN6ADDRSZ / NS_INT16SZ); i++) {
 156                 if (words[i] == 0) {
 157                         if (cur.base == -1)
 158                                 cur.base = i, cur.len = 1;
 159                         else
 160                                 cur.len++;
 161                 } else {
 162                         if (cur.base != -1) {
 163                                 if (best.base == -1 || cur.len > best.len)
 164                                         best = cur;
 165                                 cur.base = -1;
 166                         }
 167                 }
 168         }
 169         if (cur.base != -1) {
 170                 if (best.base == -1 || cur.len > best.len)
 171                         best = cur;
 172         }
 173         if (best.base != -1 && best.len < 2)
 174                 best.base = -1;
 175
 176         /*
 177          * Format the result.
 178          */
 179         tp = tmp;
 180         ep = tmp + sizeof(tmp);
 181         for (i = 0; i < (NS_IN6ADDRSZ / NS_INT16SZ); i++) {
 182                 /* Are we inside the best run of 0x00's? */
 183                 if (best.base != -1 && i >= best.base &&
 184                     i < (best.base + best.len)) {
 185                         if (i == best.base)
 186                                 *tp++ = ':';
 187                         continue;
 188                 }
 189                 /* Are we following an initial run of 0x00s or any real hex? */
 190                 if (i != 0) {
 191                         if (tp + 1 >= ep)
 192                                 return (NULL);
 193                         *tp++ = ':';
 194                 }
 195                 /* Is this address an encapsulated IPv4? */
 196                 if (i == 6 && best.base == 0 &&
 197                     (best.len == 6 ||
 198                     (best.len == 7 && words[7] != 0x0001) ||
 199                     (best.len == 5 && words[5] == 0xffff))) {
 200                         if (!inet_ntop4(src+12, tp, (socklen_t)(ep - tp)))
 201                                 return (NULL);
 202                         tp += strlen(tp);
 203                         break;
 204                 }
 205                 advance = snprintf(tp, (size_t)(ep - tp), "%x", words[i]);
 206                 if (advance <= 0 || advance >= ep - tp)
 207                         return (NULL);
 208                 tp += advance;
 209         }
 210         /* Was it a trailing run of 0x00's? */
 211         if (best.base != -1 && (best.base + best.len) ==
 212             (NS_IN6ADDRSZ / NS_INT16SZ)) {
 213                 if (tp + 1 >= ep)
 214                         return (NULL);
 215                 *tp++ = ':';
 216         }
 217         if (tp + 1 >= ep)
 218                 return (NULL);
 219         *tp++ = '\0';
 220
 221         /*
 222          * Check for overflow, copy, and we're done.
 223          */
 224         if ((size_t)(tp - tmp) > size) {
 225                 errno = ENOSPC;
 226                 return (NULL);
 227         }
 228         strlcpy(dst, tmp, size);
 229         return (dst);
 230 }
 231
 232 /*! \file */