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