compat/inet_ntop.c

   1 /*
   2  * Copyright (c) 1996-1999 by 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 DISCLAIMS
   9  * ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES
  10  * OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL INTERNET SOFTWARE
  11  * CONSORTIUM BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
  12  * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
  13  * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
  14  * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
  15  * SOFTWARE.
  16  */
  17
  18 #include <errno.h>
  19 #include <sys/types.h>
  20 #include <sys/socket.h>
  21 #include <sys/socket.h>
  22 #include <netinet/in.h>
  23 #include <arpa/inet.h>
  24 #include <stdio.h>
  25 #include <string.h>
  26
  27 #ifndef NS_INADDRSZ
  28 #define NS_INADDRSZ     4
  29 #endif
  30 #ifndef NS_IN6ADDRSZ
  31 #define NS_IN6ADDRSZ    16
  32 #endif
  33 #ifndef NS_INT16SZ
  34 #define NS_INT16SZ      2
  35 #endif
  36
  37 /*
  38  * WARNING: Don't even consider trying to compile this on a system where
  39  * sizeof(int) < 4.  sizeof(int) > 4 is fine; all the world's not a VAX.
  40  */
  41
  42 /* const char *
  43  * inet_ntop4(src, dst, size)
  44  *      format an IPv4 address
  45  * return:
  46  *      `dst' (as a const)
  47  * notes:
  48  *      (1) uses no statics
  49  *      (2) takes a u_char* not an in_addr as input
  50  * author:
  51  *      Paul Vixie, 1996.
  52  */
  53 static const char *
  54 inet_ntop4(src, dst, size)
  55         const u_char *src;
  56         char *dst;
  57         size_t size;
  58 {
  59         static const char fmt[] = "%u.%u.%u.%u";
  60         char tmp[sizeof "255.255.255.255"];
  61         int nprinted;
  62
  63         nprinted = snprintf(tmp, sizeof(tmp), fmt, src[0], src[1], src[2], src[3]);
  64         if (nprinted < 0)
  65                 return (NULL);  /* we assume "errno" was set by "snprintf()" */
  66         if ((size_t)nprinted > size) {
  67                 errno = ENOSPC;
  68                 return (NULL);
  69         }
  70         strcpy(dst, tmp);
  71         return (dst);
  72 }
  73
  74 #ifndef NO_IPV6
  75 /* const char *
  76  * inet_ntop6(src, dst, size)
  77  *      convert IPv6 binary address into presentation (printable) format
  78  * author:
  79  *      Paul Vixie, 1996.
  80  */
  81 static const char *
  82 inet_ntop6(src, dst, size)
  83         const u_char *src;
  84         char *dst;
  85         size_t size;
  86 {
  87         /*
  88          * Note that int32_t and int16_t need only be "at least" large enough
  89          * to contain a value of the specified size.  On some systems, like
  90          * Crays, there is no such thing as an integer variable with 16 bits.
  91          * Keep this in mind if you think this function should have been coded
  92          * to use pointer overlays.  All the world's not a VAX.
  93          */
  94         char tmp[sizeof "ffff:ffff:ffff:ffff:ffff:ffff:255.255.255.255"], *tp;
  95         struct { int base, len; } best, cur;
  96         unsigned int words[NS_IN6ADDRSZ / NS_INT16SZ];
  97         int i;
  98
  99         /*
 100          * Preprocess:
 101          *      Copy the input (bytewise) array into a wordwise array.
 102          *      Find the longest run of 0x00's in src[] for :: shorthanding.
 103          */
 104         memset(words, '\0', sizeof words);
 105         for (i = 0; i < NS_IN6ADDRSZ; i++)
 106                 words[i / 2] |= (src[i] << ((1 - (i % 2)) << 3));
 107         best.base = -1;
 108         cur.base = -1;
 109         for (i = 0; i < (NS_IN6ADDRSZ / NS_INT16SZ); i++) {
 110                 if (words[i] == 0) {
 111                         if (cur.base == -1)
 112                                 cur.base = i, cur.len = 1;
 113                         else
 114                                 cur.len++;
 115                 } else {
 116                         if (cur.base != -1) {
 117                                 if (best.base == -1 || cur.len > best.len)
 118                                         best = cur;
 119                                 cur.base = -1;
 120                         }
 121                 }
 122         }
 123         if (cur.base != -1) {
 124                 if (best.base == -1 || cur.len > best.len)
 125                         best = cur;
 126         }
 127         if (best.base != -1 && best.len < 2)
 128                 best.base = -1;
 129
 130         /*
 131          * Format the result.
 132          */
 133         tp = tmp;
 134         for (i = 0; i < (NS_IN6ADDRSZ / NS_INT16SZ); i++) {
 135                 /* Are we inside the best run of 0x00's? */
 136                 if (best.base != -1 && i >= best.base &&
 137                     i < (best.base + best.len)) {
 138                         if (i == best.base)
 139                                 *tp++ = ':';
 140                         continue;
 141                 }
 142                 /* Are we following an initial run of 0x00s or any real hex? */
 143                 if (i != 0)
 144                         *tp++ = ':';
 145                 /* Is this address an encapsulated IPv4? */
 146                 if (i == 6 && best.base == 0 &&
 147                     (best.len == 6 || (best.len == 5 && words[5] == 0xffff))) {
 148                         if (!inet_ntop4(src+12, tp, sizeof tmp - (tp - tmp)))
 149                                 return (NULL);
 150                         tp += strlen(tp);
 151                         break;
 152                 }
 153                 tp += snprintf(tp, sizeof tmp - (tp - tmp), "%x", words[i]);
 154         }
 155         /* Was it a trailing run of 0x00's? */
 156         if (best.base != -1 && (best.base + best.len) ==
 157             (NS_IN6ADDRSZ / NS_INT16SZ))
 158                 *tp++ = ':';
 159         *tp++ = '\0';
 160
 161         /*
 162          * Check for overflow, copy, and we're done.
 163          */
 164         if ((size_t)(tp - tmp) > size) {
 165                 errno = ENOSPC;
 166                 return (NULL);
 167         }
 168         strcpy(dst, tmp);
 169         return (dst);
 170 }
 171 #endif
 172
 173 /* char *
 174  * inet_ntop(af, src, dst, size)
 175  *      convert a network format address to presentation format.
 176  * return:
 177  *      pointer to presentation format address (`dst'), or NULL (see errno).
 178  * author:
 179  *      Paul Vixie, 1996.
 180  */
 181 const char *
 182 inet_ntop(af, src, dst, size)
 183         int af;
 184         const void *src;
 185         char *dst;
 186         size_t size;
 187 {
 188         switch (af) {
 189         case AF_INET:
 190                 return (inet_ntop4(src, dst, size));
 191 #ifndef NO_IPV6
 192         case AF_INET6:
 193                 return (inet_ntop6(src, dst, size));
 194 #endif
 195         default:
 196                 errno = EAFNOSUPPORT;
 197                 return (NULL);
 198         }
 199         /* NOTREACHED */
 200 }