lib/liblwres/lwinetntop.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: lwinetntop.c,v 1.1 2004/03/15 20:35:25 as 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 <lwres/net.h>
  30
  31 #define NS_INT16SZ       2
  32 #define NS_IN6ADDRSZ    16
  33
  34 /*
  35  * WARNING: Don't even consider trying to compile this on a system where
  36  * sizeof(int) < 4.  sizeof(int) > 4 is fine; all the world's not a VAX.
  37  */
  38
  39 static const char *inet_ntop4(const unsigned char *src, char *dst,
  40                               size_t size);
  41
  42 #ifdef AF_INET6
  43 static const char *inet_ntop6(const unsigned char *src, char *dst,
  44                               size_t size);
  45 #endif
  46
  47 /* char *
  48  * lwres_net_ntop(af, src, dst, size)
  49  *      convert a network format address to presentation format.
  50  * return:
  51  *      pointer to presentation format address (`dst'), or NULL (see errno).
  52  * author:
  53  *      Paul Vixie, 1996.
  54  */
  55 const char *
  56 lwres_net_ntop(int af, const void *src, char *dst, size_t size) {
  57         switch (af) {
  58         case AF_INET:
  59                 return (inet_ntop4(src, dst, size));
  60 #ifdef AF_INET6
  61         case AF_INET6:
  62                 return (inet_ntop6(src, dst, size));
  63 #endif
  64         default:
  65                 errno = EAFNOSUPPORT;
  66                 return (NULL);
  67         }
  68         /* NOTREACHED */
  69 }
  70
  71 /* const char *
  72  * inet_ntop4(src, dst, size)
  73  *      format an IPv4 address
  74  * return:
  75  *      `dst' (as a const)
  76  * notes:
  77  *      (1) uses no statics
  78  *      (2) takes a unsigned char* not an in_addr as input
  79  * author:
  80  *      Paul Vixie, 1996.
  81  */
  82 static const char *
  83 inet_ntop4(const unsigned char *src, char *dst, size_t size) {
  84         static const char fmt[] = "%u.%u.%u.%u";
  85         char tmp[sizeof "255.255.255.255"];
  86
  87         if ((size_t)sprintf(tmp, fmt, src[0], src[1], src[2], src[3]) >= size)
  88         {
  89                 errno = ENOSPC;
  90                 return (NULL);
  91         }
  92         strcpy(dst, tmp);
  93
  94         return (dst);
  95 }
  96
  97 /* const char *
  98  * inet_ntop6(src, dst, size)
  99  *      convert IPv6 binary address into presentation (printable) format
 100  * author:
 101  *      Paul Vixie, 1996.
 102  */
 103 #ifdef AF_INET6
 104 static const char *
 105 inet_ntop6(const unsigned char *src, char *dst, size_t size) {
 106         /*
 107          * Note that int32_t and int16_t need only be "at least" large enough
 108          * to contain a value of the specified size.  On some systems, like
 109          * Crays, there is no such thing as an integer variable with 16 bits.
 110          * Keep this in mind if you think this function should have been coded
 111          * to use pointer overlays.  All the world's not a VAX.
 112          */
 113         char tmp[sizeof "ffff:ffff:ffff:ffff:ffff:ffff:255.255.255.255"], *tp;
 114         struct { int base, len; } best, cur;
 115         unsigned int words[NS_IN6ADDRSZ / NS_INT16SZ];
 116         int i;
 117
 118         /*
 119          * Preprocess:
 120          *      Copy the input (bytewise) array into a wordwise array.
 121          *      Find the longest run of 0x00's in src[] for :: shorthanding.
 122          */
 123         memset(words, '\0', sizeof words);
 124         for (i = 0; i < NS_IN6ADDRSZ; i++)
 125                 words[i / 2] |= (src[i] << ((1 - (i % 2)) << 3));
 126         best.base = -1;
 127         cur.base = -1;
 128         for (i = 0; i < (NS_IN6ADDRSZ / NS_INT16SZ); i++) {
 129                 if (words[i] == 0) {
 130                         if (cur.base == -1)
 131                                 cur.base = i, cur.len = 1;
 132                         else
 133                                 cur.len++;
 134                 } else {
 135                         if (cur.base != -1) {
 136                                 if (best.base == -1 || cur.len > best.len)
 137                                         best = cur;
 138                                 cur.base = -1;
 139                         }
 140                 }
 141         }
 142         if (cur.base != -1) {
 143                 if (best.base == -1 || cur.len > best.len)
 144                         best = cur;
 145         }
 146         if (best.base != -1 && best.len < 2)
 147                 best.base = -1;
 148
 149         /*
 150          * Format the result.
 151          */
 152         tp = tmp;
 153         for (i = 0; i < (NS_IN6ADDRSZ / NS_INT16SZ); i++) {
 154                 /* Are we inside the best run of 0x00's? */
 155                 if (best.base != -1 && i >= best.base &&
 156                     i < (best.base + best.len)) {
 157                         if (i == best.base)
 158                                 *tp++ = ':';
 159                         continue;
 160                 }
 161                 /* Are we following an initial run of 0x00s or any real hex? */
 162                 if (i != 0)
 163                         *tp++ = ':';
 164                 /* Is this address an encapsulated IPv4? */
 165                 if (i == 6 && best.base == 0 &&
 166                     (best.len == 6 || (best.len == 5 && words[5] == 0xffff))) {
 167                         if (!inet_ntop4(src+12, tp,
 168                                         sizeof tmp - (tp - tmp)))
 169                                 return (NULL);
 170                         tp += strlen(tp);
 171                         break;
 172                 }
 173                 tp += sprintf(tp, "%x", words[i]);
 174         }
 175         /* Was it a trailing run of 0x00's? */
 176         if (best.base != -1 && (best.base + best.len) ==
 177             (NS_IN6ADDRSZ / NS_INT16SZ))
 178                 *tp++ = ':';
 179         *tp++ = '\0';
 180
 181         /*
 182          * Check for overflow, copy, and we're done.
 183          */
 184         if ((size_t)(tp - tmp) > size) {
 185                 errno = ENOSPC;
 186                 return (NULL);
 187         }
 188         strcpy(dst, tmp);
 189         return (dst);
 190 }
 191 #endif /* AF_INET6 */