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         cur.base = -1;
 102         for (i = 0; i < (NS_IN6ADDRSZ / NS_INT16SZ); i++) {
 103                 if (words[i] == 0) {
 104                         if (cur.base == -1)
 105                                 cur.base = i, cur.len = 1;
 106                         else
 107                                 cur.len++;
 108                 } else {
 109                         if (cur.base != -1) {
 110                                 if (best.base == -1 || cur.len > best.len)
 111                                         best = cur;
 112                                 cur.base = -1;
 113                         }
 114                 }
 115         }
 116         if (cur.base != -1) {
 117                 if (best.base == -1 || cur.len > best.len)
 118                         best = cur;
 119         }
 120         if (best.base != -1 && best.len < 2)
 121                 best.base = -1;
 122
 123         /*
 124          * Format the result.
 125          */
 126         tp = tmp;
 127         for (i = 0; i < (NS_IN6ADDRSZ / NS_INT16SZ); i++) {
 128                 /* Are we inside the best run of 0x00's? */
 129                 if (best.base != -1 && i >= best.base &&
 130                     i < (best.base + best.len)) {
 131                         if (i == best.base)
 132                                 *tp++ = ':';
 133                         continue;
 134                 }
 135                 /* Are we following an initial run of 0x00s or any real hex? */
 136                 if (i != 0)
 137                         *tp++ = ':';
 138                 /* Is this address an encapsulated IPv4? */
 139                 if (i == 6 && best.base == 0 &&
 140                     (best.len == 6 || (best.len == 5 && words[5] == 0xffff))) {
 141                         if (!inet_ntop4(src+12, tp, sizeof tmp - (tp - tmp)))
 142                                 return (NULL);
 143                         tp += strlen(tp);
 144                         break;
 145                 }
 146                 tp += snprintf(tp, sizeof tmp - (tp - tmp), "%x", words[i]);
 147         }
 148         /* Was it a trailing run of 0x00's? */
 149         if (best.base != -1 && (best.base + best.len) ==
 150             (NS_IN6ADDRSZ / NS_INT16SZ))
 151                 *tp++ = ':';
 152         *tp++ = '\0';
 153
 154         /*
 155          * Check for overflow, copy, and we're done.
 156          */
 157         if ((size_t)(tp - tmp) > size) {
 158                 errno = ENOSPC;
 159                 return (NULL);
 160         }
 161         strcpy(dst, tmp);
 162         return (dst);
 163 }
 164 #endif
 165
 166 /* char *
 167  * inet_ntop(af, src, dst, size)
 168  *      convert a network format address to presentation format.
 169  * return:
 170  *      pointer to presentation format address (`dst'), or NULL (see errno).
 171  * author:
 172  *      Paul Vixie, 1996.
 173  */
 174 const char *
 175 inet_ntop(int af, const void *src, char *dst, size_t size)
 176 {
 177         switch (af) {
 178         case AF_INET:
 179                 return (inet_ntop4(src, dst, size));
 180 #ifndef NO_IPV6
 181         case AF_INET6:
 182                 return (inet_ntop6(src, dst, size));
 183 #endif
 184         default:
 185                 errno = EAFNOSUPPORT;
 186                 return (NULL);
 187         }
 188         /* NOTREACHED */
 189 }