lib/replace/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
  19 #include "replace.h"
  20 #include "system/network.h"
  21
  22 #define NS_INT16SZ       2
  23 #define NS_IN6ADDRSZ    16
  24
  25 /*
  26  * WARNING: Don't even consider trying to compile this on a system where
  27  * sizeof(int) < 4.  sizeof(int) > 4 is fine; all the world's not a VAX.
  28  */
  29
  30 static const char *inet_ntop4(const unsigned char *src, char *dst,
  31                               socklen_t size);
  32
  33 #ifdef AF_INET6
  34 static const char *inet_ntop6(const unsigned char *src, char *dst,
  35                               socklen_t size);
  36 #endif
  37
  38 /* char *
  39  * isc_net_ntop(af, src, dst, size)
  40  *      convert a network format address to presentation format.
  41  * return:
  42  *      pointer to presentation format address (`dst'), or NULL (see errno).
  43  * author:
  44  *      Paul Vixie, 1996.
  45  */
  46 const char *
  47 rep_inet_ntop(int af, const void *src, char *dst, socklen_t size)
  48 {
  49         switch (af) {
  50         case AF_INET:
  51                 return (inet_ntop4(src, dst, size));
  52 #ifdef AF_INET6
  53         case AF_INET6:
  54                 return (inet_ntop6(src, dst, size));
  55 #endif
  56         default:
  57                 errno = EAFNOSUPPORT;
  58                 return (NULL);
  59         }
  60         /* NOTREACHED */
  61 }
  62
  63 /* const char *
  64  * inet_ntop4(src, dst, size)
  65  *      format an IPv4 address
  66  * return:
  67  *      `dst' (as a const)
  68  * notes:
  69  *      (1) uses no statics
  70  *      (2) takes a unsigned char* not an in_addr as input
  71  * author:
  72  *      Paul Vixie, 1996.
  73  */
  74 static const char *
  75 inet_ntop4(const unsigned char *src, char *dst, socklen_t size)
  76 {
  77         static const char *fmt = "%u.%u.%u.%u";
  78         char tmp[sizeof "255.255.255.255"];
  79         size_t len;
  80
  81         len = snprintf(tmp, sizeof tmp, fmt, src[0], src[1], src[2], src[3]);
  82         if (len >= size) {
  83                 errno = ENOSPC;
  84                 return (NULL);
  85         }
  86         memcpy(dst, tmp, len + 1);
  87
  88         return (dst);
  89 }
  90
  91 /* const char *
  92  * isc_inet_ntop6(src, dst, size)
  93  *      convert IPv6 binary address into presentation (printable) format
  94  * author:
  95  *      Paul Vixie, 1996.
  96  */
  97 #ifdef AF_INET6
  98 static const char *
  99 inet_ntop6(const unsigned char *src, char *dst, socklen_t size)
 100 {
 101         /*
 102          * Note that int32_t and int16_t need only be "at least" large enough
 103          * to contain a value of the specified size.  On some systems, like
 104          * Crays, there is no such thing as an integer variable with 16 bits.
 105          * Keep this in mind if you think this function should have been coded
 106          * to use pointer overlays.  All the world's not a VAX.
 107          */
 108         char tmp[sizeof "ffff:ffff:ffff:ffff:ffff:ffff:255.255.255.255"], *tp;
 109         struct { int base, len; } best, cur;
 110         unsigned int words[NS_IN6ADDRSZ / NS_INT16SZ];
 111         int i, inc;
 112
 113         /*
 114          * Preprocess:
 115          *      Copy the input (bytewise) array into a wordwise array.
 116          *      Find the longest run of 0x00's in src[] for :: shorthanding.
 117          */
 118         memset(words, '\0', sizeof words);
 119         for (i = 0; i < NS_IN6ADDRSZ; i++)
 120                 words[i / 2] |= (src[i] << ((1 - (i % 2)) << 3));
 121         best.base = -1;
 122         best.len = 0;
 123         cur.base = -1;
 124         cur.len = 0;
 125         for (i = 0; i < (NS_IN6ADDRSZ / NS_INT16SZ); i++) {
 126                 if (words[i] == 0) {
 127                         if (cur.base == -1)
 128                                 cur.base = i, cur.len = 1;
 129                         else
 130                                 cur.len++;
 131                 } else {
 132                         if (cur.base != -1) {
 133                                 if (best.base == -1 || cur.len > best.len)
 134                                         best = cur;
 135                                 cur.base = -1;
 136                         }
 137                 }
 138         }
 139         if (cur.base != -1) {
 140                 if (best.base == -1 || cur.len > best.len)
 141                         best = cur;
 142         }
 143         if (best.base != -1 && best.len < 2)
 144                 best.base = -1;
 145
 146         /*
 147          * Format the result.
 148          */
 149         tp = tmp;
 150         for (i = 0; i < (NS_IN6ADDRSZ / NS_INT16SZ); i++) {
 151                 /* Are we inside the best run of 0x00's? */
 152                 if (best.base != -1 && i >= best.base &&
 153                     i < (best.base + best.len)) {
 154                         if (i == best.base)
 155                                 *tp++ = ':';
 156                         continue;
 157                 }
 158                 /* Are we following an initial run of 0x00s or any real hex? */
 159                 if (i != 0)
 160                         *tp++ = ':';
 161                 /* Is this address an encapsulated IPv4? */
 162                 if (i == 6 && best.base == 0 &&
 163                     (best.len == 6 || (best.len == 5 && words[5] == 0xffff))) {
 164                         if (!inet_ntop4(src+12, tp, sizeof tmp - (tp - tmp)))
 165                                 return (NULL);
 166                         tp += strlen(tp);
 167                         break;
 168                 }
 169                 inc = snprintf(tp, 5, "%x", words[i]);
 170                 if (inc >= 5) {
 171                         abort();
 172                 }
 173                 tp += inc;
 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         memcpy(dst, tmp, tp - tmp);
 189         return (dst);
 190 }
 191 #endif /* AF_INET6 */