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