openbsd-compat/inet_ntop.c

   1 /* OPENBSD ORIGINAL: lib/libc/net/inet_ntop.c */
   2
   3 /*      $OpenBSD: inet_ntop.c,v 1.5 2002/08/23 16:27:31 itojun Exp $    */
   4
   5 /* Copyright (c) 1996 by Internet Software Consortium.
   6  *
   7  * Permission to use, copy, modify, and distribute this software for any
   8  * purpose with or without fee is hereby granted, provided that the above
   9  * copyright notice and this permission notice appear in all copies.
  10  *
  11  * THE SOFTWARE IS PROVIDED "AS IS" AND INTERNET SOFTWARE CONSORTIUM DISCLAIMS
  12  * ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES
  13  * OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL INTERNET SOFTWARE
  14  * CONSORTIUM BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
  15  * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
  16  * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
  17  * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
  18  * SOFTWARE.
  19  */
  20
  21 #include "includes.h"
  22
  23 #ifndef HAVE_INET_NTOP
  24
  25 #if defined(LIBC_SCCS) && !defined(lint)
  26 #if 0
  27 static char rcsid[] = "$From: inet_ntop.c,v 8.7 1996/08/05 08:41:18 vixie Exp $";
  28 #else
  29 static char rcsid[] = "$OpenBSD: inet_ntop.c,v 1.5 2002/08/23 16:27:31 itojun Exp $";
  30 #endif
  31 #endif /* LIBC_SCCS and not lint */
  32
  33 #include <sys/param.h>
  34 #include <sys/types.h>
  35 #include <sys/socket.h>
  36 #include <netinet/in.h>
  37 #include <arpa/inet.h>
  38 #include <arpa/nameser.h>
  39 #include <string.h>
  40 #include <errno.h>
  41 #include <stdio.h>
  42
  43 #ifndef IN6ADDRSZ
  44 #define IN6ADDRSZ   16   /* IPv6 T_AAAA */
  45 #endif
  46
  47 #ifndef INT16SZ
  48 #define INT16SZ     2    /* for systems without 16-bit ints */
  49 #endif
  50
  51 /*
  52  * WARNING: Don't even consider trying to compile this on a system where
  53  * sizeof(int) < 4.  sizeof(int) > 4 is fine; all the world's not a VAX.
  54  */
  55
  56 static const char *inet_ntop4(const u_char *src, char *dst, size_t size);
  57 static const char *inet_ntop6(const u_char *src, char *dst, size_t size);
  58
  59 /* char *
  60  * inet_ntop(af, src, dst, size)
  61  *      convert a network format address to presentation format.
  62  * return:
  63  *      pointer to presentation format address (`dst'), or NULL (see errno).
  64  * author:
  65  *      Paul Vixie, 1996.
  66  */
  67 const char *
  68 inet_ntop(af, src, dst, size)
  69         int af;
  70         const void *src;
  71         char *dst;
  72         size_t size;
  73 {
  74         switch (af) {
  75         case AF_INET:
  76                 return (inet_ntop4(src, dst, size));
  77         case AF_INET6:
  78                 return (inet_ntop6(src, dst, size));
  79         default:
  80                 errno = EAFNOSUPPORT;
  81                 return (NULL);
  82         }
  83         /* NOTREACHED */
  84 }
  85
  86 /* const char *
  87  * inet_ntop4(src, dst, size)
  88  *      format an IPv4 address, more or less like inet_ntoa()
  89  * return:
  90  *      `dst' (as a const)
  91  * notes:
  92  *      (1) uses no statics
  93  *      (2) takes a u_char* not an in_addr as input
  94  * author:
  95  *      Paul Vixie, 1996.
  96  */
  97 static const char *
  98 inet_ntop4(src, dst, size)
  99         const u_char *src;
 100         char *dst;
 101         size_t size;
 102 {
 103         static const char fmt[] = "%u.%u.%u.%u";
 104         char tmp[sizeof "255.255.255.255"];
 105         int l;
 106
 107         l = snprintf(tmp, size, fmt, src[0], src[1], src[2], src[3]);
 108         if (l <= 0 || l >= size) {
 109                 errno = ENOSPC;
 110                 return (NULL);
 111         }
 112         strlcpy(dst, tmp, size);
 113         return (dst);
 114 }
 115
 116 /* const char *
 117  * inet_ntop6(src, dst, size)
 118  *      convert IPv6 binary address into presentation (printable) format
 119  * author:
 120  *      Paul Vixie, 1996.
 121  */
 122 static const char *
 123 inet_ntop6(src, dst, size)
 124         const u_char *src;
 125         char *dst;
 126         size_t size;
 127 {
 128         /*
 129          * Note that int32_t and int16_t need only be "at least" large enough
 130          * to contain a value of the specified size.  On some systems, like
 131          * Crays, there is no such thing as an integer variable with 16 bits.
 132          * Keep this in mind if you think this function should have been coded
 133          * to use pointer overlays.  All the world's not a VAX.
 134          */
 135         char tmp[sizeof "ffff:ffff:ffff:ffff:ffff:ffff:255.255.255.255"];
 136         char *tp, *ep;
 137         struct { int base, len; } best, cur;
 138         u_int words[IN6ADDRSZ / INT16SZ];
 139         int i;
 140         int advance;
 141
 142         /*
 143          * Preprocess:
 144          *      Copy the input (bytewise) array into a wordwise array.
 145          *      Find the longest run of 0x00's in src[] for :: shorthanding.
 146          */
 147         memset(words, '\0', sizeof words);
 148         for (i = 0; i < IN6ADDRSZ; i++)
 149                 words[i / 2] |= (src[i] << ((1 - (i % 2)) << 3));
 150         best.base = -1;
 151         cur.base = -1;
 152         for (i = 0; i < (IN6ADDRSZ / INT16SZ); i++) {
 153                 if (words[i] == 0) {
 154                         if (cur.base == -1)
 155                                 cur.base = i, cur.len = 1;
 156                         else
 157                                 cur.len++;
 158                 } else {
 159                         if (cur.base != -1) {
 160                                 if (best.base == -1 || cur.len > best.len)
 161                                         best = cur;
 162                                 cur.base = -1;
 163                         }
 164                 }
 165         }
 166         if (cur.base != -1) {
 167                 if (best.base == -1 || cur.len > best.len)
 168                         best = cur;
 169         }
 170         if (best.base != -1 && best.len < 2)
 171                 best.base = -1;
 172
 173         /*
 174          * Format the result.
 175          */
 176         tp = tmp;
 177         ep = tmp + sizeof(tmp);
 178         for (i = 0; i < (IN6ADDRSZ / INT16SZ) && tp < ep; i++) {
 179                 /* Are we inside the best run of 0x00's? */
 180                 if (best.base != -1 && i >= best.base &&
 181                     i < (best.base + best.len)) {
 182                         if (i == best.base) {
 183                                 if (tp + 1 >= ep)
 184                                         return (NULL);
 185                                 *tp++ = ':';
 186                         }
 187                         continue;
 188                 }
 189                 /* Are we following an initial run of 0x00s or any real hex? */
 190                 if (i != 0) {
 191                         if (tp + 1 >= ep)
 192                                 return (NULL);
 193                         *tp++ = ':';
 194                 }
 195                 /* Is this address an encapsulated IPv4? */
 196                 if (i == 6 && best.base == 0 &&
 197                     (best.len == 6 || (best.len == 5 && words[5] == 0xffff))) {
 198                         if (!inet_ntop4(src+12, tp, (size_t)(ep - tp)))
 199                                 return (NULL);
 200                         tp += strlen(tp);
 201                         break;
 202                 }
 203                 advance = snprintf(tp, ep - tp, "%x", words[i]);
 204                 if (advance <= 0 || advance >= ep - tp)
 205                         return (NULL);
 206                 tp += advance;
 207         }
 208         /* Was it a trailing run of 0x00's? */
 209         if (best.base != -1 && (best.base + best.len) == (IN6ADDRSZ / INT16SZ)) {
 210                 if (tp + 1 >= ep)
 211                         return (NULL);
 212                 *tp++ = ':';
 213         }
 214         if (tp + 1 >= ep)
 215                 return (NULL);
 216         *tp++ = '\0';
 217
 218         /*
 219          * Check for overflow, copy, and we're done.
 220          */
 221         if ((size_t)(tp - tmp) > size) {
 222                 errno = ENOSPC;
 223                 return (NULL);
 224         }
 225         strlcpy(dst, tmp, size);
 226         return (dst);
 227 }
 228
 229 #endif /* !HAVE_INET_NTOP */