openbsd-compat/inet_ntop.c

   1 /*      $OpenBSD: inet_ntop.c,v 1.7 2005/08/06 20:30:03 espie Exp $     */
   2
   3 /* Copyright (c) 1996 by Internet Software Consortium.
   4  *
   5  * Permission to use, copy, modify, and distribute this software for any
   6  * purpose with or without fee is hereby granted, provided that the above
   7  * copyright notice and this permission notice appear in all copies.
   8  *
   9  * THE SOFTWARE IS PROVIDED "AS IS" AND INTERNET SOFTWARE CONSORTIUM DISCLAIMS
  10  * ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES
  11  * OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL INTERNET SOFTWARE
  12  * CONSORTIUM BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
  13  * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
  14  * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
  15  * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
  16  * SOFTWARE.
  17  */
  18
  19 /* OPENBSD ORIGINAL: lib/libc/net/inet_ntop.c */
  20
  21 #include "includes.h"
  22
  23 #ifndef HAVE_INET_NTOP
  24
  25 #include <sys/param.h>
  26 #include <sys/types.h>
  27 #include <sys/socket.h>
  28 #include <netinet/in.h>
  29 #include <arpa/inet.h>
  30 #include <arpa/nameser.h>
  31 #include <string.h>
  32 #include <errno.h>
  33 #include <stdio.h>
  34
  35 #ifndef IN6ADDRSZ
  36 #define IN6ADDRSZ   16   /* IPv6 T_AAAA */
  37 #endif
  38
  39 #ifndef INT16SZ
  40 #define INT16SZ     2    /* for systems without 16-bit ints */
  41 #endif
  42
  43 /*
  44  * WARNING: Don't even consider trying to compile this on a system where
  45  * sizeof(int) < 4.  sizeof(int) > 4 is fine; all the world's not a VAX.
  46  */
  47
  48 static const char *inet_ntop4(const u_char *src, char *dst, size_t size);
  49 static const char *inet_ntop6(const u_char *src, char *dst, size_t size);
  50
  51 /* char *
  52  * inet_ntop(af, src, dst, size)
  53  *      convert a network format address to presentation format.
  54  * return:
  55  *      pointer to presentation format address (`dst'), or NULL (see errno).
  56  * author:
  57  *      Paul Vixie, 1996.
  58  */
  59 const char *
  60 inet_ntop(int af, const void *src, char *dst, size_t size)
  61 {
  62         switch (af) {
  63         case AF_INET:
  64                 return (inet_ntop4(src, dst, size));
  65         case AF_INET6:
  66                 return (inet_ntop6(src, dst, size));
  67         default:
  68                 errno = EAFNOSUPPORT;
  69                 return (NULL);
  70         }
  71         /* NOTREACHED */
  72 }
  73
  74 /* const char *
  75  * inet_ntop4(src, dst, size)
  76  *      format an IPv4 address, more or less like inet_ntoa()
  77  * return:
  78  *      `dst' (as a const)
  79  * notes:
  80  *      (1) uses no statics
  81  *      (2) takes a u_char* not an in_addr as input
  82  * author:
  83  *      Paul Vixie, 1996.
  84  */
  85 static const char *
  86 inet_ntop4(const u_char *src, char *dst, size_t size)
  87 {
  88         static const char fmt[] = "%u.%u.%u.%u";
  89         char tmp[sizeof "255.255.255.255"];
  90         int l;
  91
  92         l = snprintf(tmp, size, fmt, src[0], src[1], src[2], src[3]);
  93         if (l <= 0 || l >= size) {
  94                 errno = ENOSPC;
  95                 return (NULL);
  96         }
  97         strlcpy(dst, tmp, size);
  98         return (dst);
  99 }
 100
 101 /* const char *
 102  * inet_ntop6(src, dst, size)
 103  *      convert IPv6 binary address into presentation (printable) format
 104  * author:
 105  *      Paul Vixie, 1996.
 106  */
 107 static const char *
 108 inet_ntop6(const u_char *src, char *dst, size_t size)
 109 {
 110         /*
 111          * Note that int32_t and int16_t need only be "at least" large enough
 112          * to contain a value of the specified size.  On some systems, like
 113          * Crays, there is no such thing as an integer variable with 16 bits.
 114          * Keep this in mind if you think this function should have been coded
 115          * to use pointer overlays.  All the world's not a VAX.
 116          */
 117         char tmp[sizeof "ffff:ffff:ffff:ffff:ffff:ffff:255.255.255.255"];
 118         char *tp, *ep;
 119         struct { int base, len; } best, cur;
 120         u_int words[IN6ADDRSZ / INT16SZ];
 121         int i;
 122         int advance;
 123
 124         /*
 125          * Preprocess:
 126          *      Copy the input (bytewise) array into a wordwise array.
 127          *      Find the longest run of 0x00's in src[] for :: shorthanding.
 128          */
 129         memset(words, '\0', sizeof words);
 130         for (i = 0; i < IN6ADDRSZ; i++)
 131                 words[i / 2] |= (src[i] << ((1 - (i % 2)) << 3));
 132         best.base = -1;
 133         cur.base = -1;
 134         for (i = 0; i < (IN6ADDRSZ / INT16SZ); i++) {
 135                 if (words[i] == 0) {
 136                         if (cur.base == -1)
 137                                 cur.base = i, cur.len = 1;
 138                         else
 139                                 cur.len++;
 140                 } else {
 141                         if (cur.base != -1) {
 142                                 if (best.base == -1 || cur.len > best.len)
 143                                         best = cur;
 144                                 cur.base = -1;
 145                         }
 146                 }
 147         }
 148         if (cur.base != -1) {
 149                 if (best.base == -1 || cur.len > best.len)
 150                         best = cur;
 151         }
 152         if (best.base != -1 && best.len < 2)
 153                 best.base = -1;
 154
 155         /*
 156          * Format the result.
 157          */
 158         tp = tmp;
 159         ep = tmp + sizeof(tmp);
 160         for (i = 0; i < (IN6ADDRSZ / INT16SZ) && tp < ep; i++) {
 161                 /* Are we inside the best run of 0x00's? */
 162                 if (best.base != -1 && i >= best.base &&
 163                     i < (best.base + best.len)) {
 164                         if (i == best.base) {
 165                                 if (tp + 1 >= ep)
 166                                         return (NULL);
 167                                 *tp++ = ':';
 168                         }
 169                         continue;
 170                 }
 171                 /* Are we following an initial run of 0x00s or any real hex? */
 172                 if (i != 0) {
 173                         if (tp + 1 >= ep)
 174                                 return (NULL);
 175                         *tp++ = ':';
 176                 }
 177                 /* Is this address an encapsulated IPv4? */
 178                 if (i == 6 && best.base == 0 &&
 179                     (best.len == 6 || (best.len == 5 && words[5] == 0xffff))) {
 180                         if (!inet_ntop4(src+12, tp, (size_t)(ep - tp)))
 181                                 return (NULL);
 182                         tp += strlen(tp);
 183                         break;
 184                 }
 185                 advance = snprintf(tp, ep - tp, "%x", words[i]);
 186                 if (advance <= 0 || advance >= ep - tp)
 187                         return (NULL);
 188                 tp += advance;
 189         }
 190         /* Was it a trailing run of 0x00's? */
 191         if (best.base != -1 && (best.base + best.len) == (IN6ADDRSZ / INT16SZ)) {
 192                 if (tp + 1 >= ep)
 193                         return (NULL);
 194                 *tp++ = ':';
 195         }
 196         if (tp + 1 >= ep)
 197                 return (NULL);
 198         *tp++ = '\0';
 199
 200         /*
 201          * Check for overflow, copy, and we're done.
 202          */
 203         if ((size_t)(tp - tmp) > size) {
 204                 errno = ENOSPC;
 205                 return (NULL);
 206         }
 207         strlcpy(dst, tmp, size);
 208         return (dst);
 209 }
 210
 211 #endif /* !HAVE_INET_NTOP */