contrib/bind/lib/bind/inet/inet_ntop.c

   1 /*
   2  * Copyright (c) 2004 by Internet Systems Consortium, Inc. ("ISC")
   3  * Copyright (c) 1996-1999 by Internet Software Consortium.
   4  *
   5  * Permission to use, copy, modify, and 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
  10  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
  11  * MERCHANTABILITY AND FITNESS.  IN NO EVENT SHALL ISC BE LIABLE FOR
  12  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
  13  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
  14  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT
  15  * OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  16  */
  17
  18 #if defined(LIBC_SCCS) && !defined(lint)
  19 static const char rcsid[] = "$Id: inet_ntop.c,v 1.5 2005/11/03 22:59:52 marka Exp $";
  20 #endif /* LIBC_SCCS and not lint */
  21
  22 #include "port_before.h"
  23
  24 #include <sys/param.h>
  25 #include <sys/types.h>
  26 #include <sys/socket.h>
  27
  28 #include <netinet/in.h>
  29 #include "arpa/inet.h"
  30 #include <arpa/nameser.h>
  31
  32 #include <errno.h>
  33 #include <stdio.h>
  34 #include <string.h>
  35
  36 #include "port_after.h"
  37
  38 #ifdef SPRINTF_CHAR
  39 # define SPRINTF(x) strlen(sprintf/**/x)
  40 #else
  41 # define SPRINTF(x) ((size_t)sprintf x)
  42 #endif
  43
  44 /*%
  45  * WARNING: Don't even consider trying to compile this on a system where
  46  * sizeof(int) < 4.  sizeof(int) > 4 is fine; all the world's not a VAX.
  47  */
  48
  49 static const char *inet_ntop4 __P((const u_char *src, char *dst, size_t size));
  50 static const char *inet_ntop6 __P((const u_char *src, char *dst, size_t size));
  51
  52 /* char *
  53  * inet_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 inet_ntop(af, src, dst, size)
  62         int af;
  63         const void *src;
  64         char *dst;
  65         size_t size;
  66 {
  67         switch (af) {
  68         case AF_INET:
  69                 return (inet_ntop4(src, dst, size));
  70         case AF_INET6:
  71                 return (inet_ntop6(src, dst, size));
  72         default:
  73                 errno = EAFNOSUPPORT;
  74                 return (NULL);
  75         }
  76         /* NOTREACHED */
  77 }
  78
  79 /* const char *
  80  * inet_ntop4(src, dst, size)
  81  *      format an IPv4 address
  82  * return:
  83  *      `dst' (as a const)
  84  * notes:
  85  *      (1) uses no statics
  86  *      (2) takes a u_char* not an in_addr as input
  87  * author:
  88  *      Paul Vixie, 1996.
  89  */
  90 static const char *
  91 inet_ntop4(src, dst, size)
  92         const u_char *src;
  93         char *dst;
  94         size_t size;
  95 {
  96         static const char fmt[] = "%u.%u.%u.%u";
  97         char tmp[sizeof "255.255.255.255"];
  98
  99         if (SPRINTF((tmp, fmt, src[0], src[1], src[2], src[3])) >= size) {
 100                 errno = ENOSPC;
 101                 return (NULL);
 102         }
 103         strcpy(dst, tmp);
 104         return (dst);
 105 }
 106
 107 /* const char *
 108  * inet_ntop6(src, dst, size)
 109  *      convert IPv6 binary address into presentation (printable) format
 110  * author:
 111  *      Paul Vixie, 1996.
 112  */
 113 static const char *
 114 inet_ntop6(src, dst, size)
 115         const u_char *src;
 116         char *dst;
 117         size_t size;
 118 {
 119         /*
 120          * Note that int32_t and int16_t need only be "at least" large enough
 121          * to contain a value of the specified size.  On some systems, like
 122          * Crays, there is no such thing as an integer variable with 16 bits.
 123          * Keep this in mind if you think this function should have been coded
 124          * to use pointer overlays.  All the world's not a VAX.
 125          */
 126         char tmp[sizeof "ffff:ffff:ffff:ffff:ffff:ffff:255.255.255.255"], *tp;
 127         struct { int base, len; } best, cur;
 128         u_int words[NS_IN6ADDRSZ / NS_INT16SZ];
 129         int i;
 130
 131         /*
 132          * Preprocess:
 133          *      Copy the input (bytewise) array into a wordwise array.
 134          *      Find the longest run of 0x00's in src[] for :: shorthanding.
 135          */
 136         memset(words, '\0', sizeof words);
 137         for (i = 0; i < NS_IN6ADDRSZ; i++)
 138                 words[i / 2] |= (src[i] << ((1 - (i % 2)) << 3));
 139         best.base = -1;
 140         best.len = 0;
 141         cur.base = -1;
 142         cur.len = 0;
 143         for (i = 0; i < (NS_IN6ADDRSZ / NS_INT16SZ); i++) {
 144                 if (words[i] == 0) {
 145                         if (cur.base == -1)
 146                                 cur.base = i, cur.len = 1;
 147                         else
 148                                 cur.len++;
 149                 } else {
 150                         if (cur.base != -1) {
 151                                 if (best.base == -1 || cur.len > best.len)
 152                                         best = cur;
 153                                 cur.base = -1;
 154                         }
 155                 }
 156         }
 157         if (cur.base != -1) {
 158                 if (best.base == -1 || cur.len > best.len)
 159                         best = cur;
 160         }
 161         if (best.base != -1 && best.len < 2)
 162                 best.base = -1;
 163
 164         /*
 165          * Format the result.
 166          */
 167         tp = tmp;
 168         for (i = 0; i < (NS_IN6ADDRSZ / NS_INT16SZ); i++) {
 169                 /* Are we inside the best run of 0x00's? */
 170                 if (best.base != -1 && i >= best.base &&
 171                     i < (best.base + best.len)) {
 172                         if (i == best.base)
 173                                 *tp++ = ':';
 174                         continue;
 175                 }
 176                 /* Are we following an initial run of 0x00s or any real hex? */
 177                 if (i != 0)
 178                         *tp++ = ':';
 179                 /* Is this address an encapsulated IPv4? */
 180                 if (i == 6 && best.base == 0 && (best.len == 6 ||
 181                     (best.len == 7 && words[7] != 0x0001) ||
 182                     (best.len == 5 && words[5] == 0xffff))) {
 183                         if (!inet_ntop4(src+12, tp, sizeof tmp - (tp - tmp)))
 184                                 return (NULL);
 185                         tp += strlen(tp);
 186                         break;
 187                 }
 188                 tp += SPRINTF((tp, "%x", words[i]));
 189         }
 190         /* Was it a trailing run of 0x00's? */
 191         if (best.base != -1 && (best.base + best.len) ==
 192             (NS_IN6ADDRSZ / NS_INT16SZ))
 193                 *tp++ = ':';
 194         *tp++ = '\0';
 195
 196         /*
 197          * Check for overflow, copy, and we're done.
 198          */
 199         if ((size_t)(tp - tmp) > size) {
 200                 errno = ENOSPC;
 201                 return (NULL);
 202         }
 203         strcpy(dst, tmp);
 204         return (dst);
 205 }
 206
 207 #ifdef _LIBC
 208 /*
 209  * Weak aliases for applications that use certain private entry points,
 210  * and fail to include <arpa/inet.h>.
 211  */
 212 #undef inet_ntop
 213 __weak_reference(__inet_ntop, inet_ntop);
 214 #endif
 215 /*! \file */