contrib/ntp/libisc/inet_ntop.c

   1 /*
   2  * Copyright (C) 1996-2001  Internet Software Consortium.
   3  *
   4  * Permission to use, copy, modify, and distribute this software for any
   5  * purpose with or without fee is hereby granted, provided that the above
   6  * copyright notice and this permission notice appear in all copies.
   7  *
   8  * THE SOFTWARE IS PROVIDED "AS IS" AND INTERNET SOFTWARE CONSORTIUM
   9  * DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL
  10  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL
  11  * INTERNET SOFTWARE CONSORTIUM BE LIABLE FOR ANY SPECIAL, DIRECT,
  12  * INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING
  13  * FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT,
  14  * NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION
  15  * WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  16  */
  17
  18 #if defined(LIBC_SCCS) && !defined(lint)
  19 static char rcsid[] =
  20         "$Id: inet_ntop.c,v 1.13 2001/11/27 01:56:00 gson Exp $";
  21 #endif /* LIBC_SCCS and not lint */
  22
  23 #include <config.h>
  24
  25 #include <errno.h>
  26 #include <stdio.h>
  27 #include <string.h>
  28
  29 #include <isc/net.h>
  30
  31 #include "ntp_sprintf.h"
  32
  33 #define NS_INT16SZ       2
  34 #define NS_IN6ADDRSZ    16
  35
  36 /*
  37  * WARNING: Don't even consider trying to compile this on a system where
  38  * sizeof(int) < 4.  sizeof(int) > 4 is fine; all the world's not a VAX.
  39  */
  40
  41 static const char *inet_ntop4(const unsigned char *src, char *dst,
  42                               size_t size);
  43
  44 #ifdef AF_INET6
  45 static const char *inet_ntop6(const unsigned char *src, char *dst,
  46                               size_t size);
  47 #endif
  48
  49 /* char *
  50  * isc_net_ntop(af, src, dst, size)
  51  *      convert a network format address to presentation format.
  52  * return:
  53  *      pointer to presentation format address (`dst'), or NULL (see errno).
  54  * author:
  55  *      Paul Vixie, 1996.
  56  */
  57 const char *
  58 isc_net_ntop(int af, const void *src, char *dst, size_t size)
  59 {
  60         switch (af) {
  61         case AF_INET:
  62                 return (inet_ntop4(src, dst, size));
  63 #ifdef AF_INET6
  64         case AF_INET6:
  65                 return (inet_ntop6(src, dst, size));
  66 #endif
  67         default:
  68                 errno = EAFNOSUPPORT;
  69                 return (NULL);
  70         }
  71         /* NOTREACHED */
  72 }
  73
  74 /* const char *
  75  * inet_ntop4(src, dst, size)
  76  *      format an IPv4 address
  77  * return:
  78  *      `dst' (as a const)
  79  * notes:
  80  *      (1) uses no statics
  81  *      (2) takes a unsigned char* not an in_addr as input
  82  * author:
  83  *      Paul Vixie, 1996.
  84  */
  85 static const char *
  86 inet_ntop4(const unsigned char *src, char *dst, size_t size)
  87 {
  88         static const char *fmt = "%u.%u.%u.%u";
  89         char tmp[sizeof("255.255.255.255")];
  90
  91         if (SPRINTF((tmp, fmt, src[0], src[1], src[2], src[3])) >= size)
  92         {
  93                 errno = ENOSPC;
  94                 return (NULL);
  95         }
  96         strcpy(dst, tmp);
  97
  98         return (dst);
  99 }
 100
 101 /* const char *
 102  * isc_inet_ntop6(src, dst, size)
 103  *      convert IPv6 binary address into presentation (printable) format
 104  * author:
 105  *      Paul Vixie, 1996.
 106  */
 107 #ifdef AF_INET6
 108 static const char *
 109 inet_ntop6(const unsigned char *src, char *dst, size_t size)
 110 {
 111         /*
 112          * Note that int32_t and int16_t need only be "at least" large enough
 113          * to contain a value of the specified size.  On some systems, like
 114          * Crays, there is no such thing as an integer variable with 16 bits.
 115          * Keep this in mind if you think this function should have been coded
 116          * to use pointer overlays.  All the world's not a VAX.
 117          */
 118         char tmp[sizeof("ffff:ffff:ffff:ffff:ffff:ffff:255.255.255.255")], *tp;
 119         struct { int base, len; } best, cur;
 120         unsigned int words[NS_IN6ADDRSZ / NS_INT16SZ];
 121         int i;
 122
 123         /*
 124          * Preprocess:
 125          *      Copy the input (bytewise) array into a wordwise array.
 126          *      Find the longest run of 0x00's in src[] for :: shorthanding.
 127          */
 128         memset(words, '\0', sizeof(words));
 129         for (i = 0; i < NS_IN6ADDRSZ; i++)
 130                 words[i / 2] |= (src[i] << ((1 - (i % 2)) << 3));
 131         best.base = -1;
 132         best.len = 0;
 133         cur.base = -1;
 134         cur.len = 0;
 135         for (i = 0; i < (NS_IN6ADDRSZ / NS_INT16SZ); i++) {
 136                 if (words[i] == 0) {
 137                         if (cur.base == -1)
 138                                 cur.base = i, cur.len = 1;
 139                         else
 140                                 cur.len++;
 141                 } else {
 142                         if (cur.base != -1) {
 143                                 if (best.base == -1 || cur.len > best.len)
 144                                         best = cur;
 145                                 cur.base = -1;
 146                         }
 147                 }
 148         }
 149         if (cur.base != -1) {
 150                 if (best.base == -1 || cur.len > best.len)
 151                         best = cur;
 152         }
 153         if (best.base != -1 && best.len < 2)
 154                 best.base = -1;
 155
 156         /*
 157          * Format the result.
 158          */
 159         tp = tmp;
 160         for (i = 0; i < (NS_IN6ADDRSZ / NS_INT16SZ); i++) {
 161                 /* Are we inside the best run of 0x00's? */
 162                 if (best.base != -1 && i >= best.base &&
 163                     i < (best.base + best.len)) {
 164                         if (i == best.base)
 165                                 *tp++ = ':';
 166                         continue;
 167                 }
 168                 /* Are we following an initial run of 0x00s or any real hex? */
 169                 if (i != 0)
 170                         *tp++ = ':';
 171                 /* Is this address an encapsulated IPv4? */
 172                 if (i == 6 && best.base == 0 &&
 173                     (best.len == 6 || (best.len == 5 && words[5] == 0xffff))) {
 174                         if (!inet_ntop4(src+12, tp,
 175                                         sizeof(tmp) - (tp - tmp)))
 176                                 return (NULL);
 177                         tp += strlen(tp);
 178                         break;
 179                 }
 180                 tp += SPRINTF((tp, "%x", words[i]));
 181         }
 182         /* Was it a trailing run of 0x00's? */
 183         if (best.base != -1 && (best.base + best.len) ==
 184             (NS_IN6ADDRSZ / NS_INT16SZ))
 185                 *tp++ = ':';
 186         *tp++ = '\0';
 187
 188         /*
 189          * Check for overflow, copy, and we're done.
 190          */
 191         if ((size_t)(tp - tmp) > size) {
 192                 errno = ENOSPC;
 193                 return (NULL);
 194         }
 195         strcpy(dst, tmp);
 196         return (dst);
 197 }
 198 #endif /* AF_INET6 */