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