dist/ntp/libisc/inet_ntop.c

   1 /*      $NetBSD$        */
   2
   3 /*
   4  * Copyright (C) 1996-2001  Internet Software Consortium.
   5  *
   6  * Permission to use, copy, modify, and distribute this software for any
   7  * purpose with or without fee is hereby granted, provided that the above
   8  * copyright notice and this permission notice appear in all copies.
   9  *
  10  * THE SOFTWARE IS PROVIDED "AS IS" AND INTERNET SOFTWARE CONSORTIUM
  11  * DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL
  12  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL
  13  * INTERNET SOFTWARE CONSORTIUM BE LIABLE FOR ANY SPECIAL, DIRECT,
  14  * INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING
  15  * FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT,
  16  * NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION
  17  * WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  18  */
  19
  20 #if defined(LIBC_SCCS) && !defined(lint)
  21 static char rcsid[] =
  22         "Id: inet_ntop.c,v 1.13 2001/11/27 01:56:00 gson Exp";
  23 #endif /* LIBC_SCCS and not lint */
  24
  25 #include <config.h>
  26
  27 #include <errno.h>
  28 #include <stdio.h>
  29 #include <string.h>
  30
  31 #include <isc/net.h>
  32
  33 #include "ntp_sprintf.h"
  34
  35 #define NS_INT16SZ       2
  36 #define NS_IN6ADDRSZ    16
  37
  38 /*
  39  * WARNING: Don't even consider trying to compile this on a system where
  40  * sizeof(int) < 4.  sizeof(int) > 4 is fine; all the world's not a VAX.
  41  */
  42
  43 static const char *inet_ntop4(const unsigned char *src, char *dst,
  44                               size_t size);
  45
  46 #ifdef AF_INET6
  47 static const char *inet_ntop6(const unsigned char *src, char *dst,
  48                               size_t size);
  49 #endif
  50
  51 /* char *
  52  * isc_net_ntop(af, src, dst, size)
  53  *      convert a network format address to presentation format.
  54  * return:
  55  *      pointer to presentation format address (`dst'), or NULL (see errno).
  56  * author:
  57  *      Paul Vixie, 1996.
  58  */
  59 const char *
  60 isc_net_ntop(int af, const void *src, char *dst, size_t size)
  61 {
  62         switch (af) {
  63         case AF_INET:
  64                 return (inet_ntop4(src, dst, size));
  65 #ifdef AF_INET6
  66         case AF_INET6:
  67                 return (inet_ntop6(src, dst, size));
  68 #endif
  69         default:
  70                 errno = EAFNOSUPPORT;
  71                 return (NULL);
  72         }
  73         /* NOTREACHED */
  74 }
  75
  76 /* const char *
  77  * inet_ntop4(src, dst, size)
  78  *      format an IPv4 address
  79  * return:
  80  *      `dst' (as a const)
  81  * notes:
  82  *      (1) uses no statics
  83  *      (2) takes a unsigned char* not an in_addr as input
  84  * author:
  85  *      Paul Vixie, 1996.
  86  */
  87 static const char *
  88 inet_ntop4(const unsigned char *src, char *dst, size_t size)
  89 {
  90         static const char *fmt = "%u.%u.%u.%u";
  91         char tmp[sizeof("255.255.255.255")];
  92
  93         if (SPRINTF((tmp, fmt, src[0], src[1], src[2], src[3])) >= size)
  94         {
  95                 errno = ENOSPC;
  96                 return (NULL);
  97         }
  98         strcpy(dst, tmp);
  99
 100         return (dst);
 101 }
 102
 103 /* const char *
 104  * isc_inet_ntop6(src, dst, size)
 105  *      convert IPv6 binary address into presentation (printable) format
 106  * author:
 107  *      Paul Vixie, 1996.
 108  */
 109 #ifdef AF_INET6
 110 static const char *
 111 inet_ntop6(const unsigned char *src, char *dst, size_t size)
 112 {
 113         /*
 114          * Note that int32_t and int16_t need only be "at least" large enough
 115          * to contain a value of the specified size.  On some systems, like
 116          * Crays, there is no such thing as an integer variable with 16 bits.
 117          * Keep this in mind if you think this function should have been coded
 118          * to use pointer overlays.  All the world's not a VAX.
 119          */
 120         char tmp[sizeof("ffff:ffff:ffff:ffff:ffff:ffff:255.255.255.255")], *tp;
 121         struct { int base, len; } best, cur;
 122         unsigned int words[NS_IN6ADDRSZ / NS_INT16SZ];
 123         int i;
 124
 125         /*
 126          * Preprocess:
 127          *      Copy the input (bytewise) array into a wordwise array.
 128          *      Find the longest run of 0x00's in src[] for :: shorthanding.
 129          */
 130         memset(words, '\0', sizeof(words));
 131         for (i = 0; i < NS_IN6ADDRSZ; i++)
 132                 words[i / 2] |= (src[i] << ((1 - (i % 2)) << 3));
 133         best.base = -1;
 134         best.len = 0;
 135         cur.base = -1;
 136         cur.len = 0;
 137         for (i = 0; i < (NS_IN6ADDRSZ / NS_INT16SZ); i++) {
 138                 if (words[i] == 0) {
 139                         if (cur.base == -1)
 140                                 cur.base = i, cur.len = 1;
 141                         else
 142                                 cur.len++;
 143                 } else {
 144                         if (cur.base != -1) {
 145                                 if (best.base == -1 || cur.len > best.len)
 146                                         best = cur;
 147                                 cur.base = -1;
 148                         }
 149                 }
 150         }
 151         if (cur.base != -1) {
 152                 if (best.base == -1 || cur.len > best.len)
 153                         best = cur;
 154         }
 155         if (best.base != -1 && best.len < 2)
 156                 best.base = -1;
 157
 158         /*
 159          * Format the result.
 160          */
 161         tp = tmp;
 162         for (i = 0; i < (NS_IN6ADDRSZ / NS_INT16SZ); i++) {
 163                 /* Are we inside the best run of 0x00's? */
 164                 if (best.base != -1 && i >= best.base &&
 165                     i < (best.base + best.len)) {
 166                         if (i == best.base)
 167                                 *tp++ = ':';
 168                         continue;
 169                 }
 170                 /* Are we following an initial run of 0x00s or any real hex? */
 171                 if (i != 0)
 172                         *tp++ = ':';
 173                 /* Is this address an encapsulated IPv4? */
 174                 if (i == 6 && best.base == 0 &&
 175                     (best.len == 6 || (best.len == 5 && words[5] == 0xffff))) {
 176                         if (!inet_ntop4(src+12, tp,
 177                                         sizeof(tmp) - (tp - tmp)))
 178                                 return (NULL);
 179                         tp += strlen(tp);
 180                         break;
 181                 }
 182                 tp += SPRINTF((tp, "%x", words[i]));
 183         }
 184         /* Was it a trailing run of 0x00's? */
 185         if (best.base != -1 && (best.base + best.len) ==
 186             (NS_IN6ADDRSZ / NS_INT16SZ))
 187                 *tp++ = ':';
 188         *tp++ = '\0';
 189
 190         /*
 191          * Check for overflow, copy, and we're done.
 192          */
 193         if ((size_t)(tp - tmp) > size) {
 194                 errno = ENOSPC;
 195                 return (NULL);
 196         }
 197         strcpy(dst, tmp);
 198         return (dst);
 199 }
 200 #endif /* AF_INET6 */