lib/libc/inet/inet_cidr_ntop.c

   1 /*      $NetBSD: inet_cidr_ntop.c,v 1.7 2009/04/12 17:07:16 christos Exp $      */
   2
   3 /*
   4  * Copyright (c) 2004 by Internet Systems Consortium, Inc. ("ISC")
   5  * Copyright (c) 1998,1999 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 ISC DISCLAIMS ALL WARRANTIES
  12  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
  13  * MERCHANTABILITY AND FITNESS.  IN NO EVENT SHALL ISC BE LIABLE FOR
  14  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
  15  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
  16  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT
  17  * OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  18  */
  19
  20 #include <sys/cdefs.h>
  21 #if defined(LIBC_SCCS) && !defined(lint)
  22 #if 0
  23 static const char rcsid[] = "Id: inet_cidr_ntop.c,v 1.7 2006/10/11 02:18:18 marka Exp";
  24 #else
  25 __RCSID("$NetBSD: inet_cidr_ntop.c,v 1.7 2009/04/12 17:07:16 christos Exp $");
  26 #endif
  27 #endif
  28
  29 #include "port_before.h"
  30
  31 #include "namespace.h"
  32 #include <sys/types.h>
  33 #include <sys/socket.h>
  34 #include <netinet/in.h>
  35 #include <arpa/nameser.h>
  36 #include <arpa/inet.h>
  37
  38 #include <errno.h>
  39 #include <stdio.h>
  40 #include <string.h>
  41 #include <stdlib.h>
  42
  43 #include "port_after.h"
  44
  45 #ifdef __weak_alias
  46 __weak_alias(inet_cidr_ntop,_inet_cidr_ntop)
  47 #endif
  48
  49 #ifdef SPRINTF_CHAR
  50 # define SPRINTF(x) strlen(sprintf/**/x)
  51 #else
  52 # define SPRINTF(x) ((size_t)sprintf x)
  53 #endif
  54
  55 static char *
  56 inet_cidr_ntop_ipv4(const u_char *src, int bits, char *dst, size_t size);
  57 static char *
  58 inet_cidr_ntop_ipv6(const u_char *src, int bits, char *dst, size_t size);
  59
  60 /*%
  61  * char *
  62  * inet_cidr_ntop(af, src, bits, dst, size)
  63  *      convert network address from network to presentation format.
  64  *      "src"'s size is determined from its "af".
  65  * return:
  66  *      pointer to dst, or NULL if an error occurred (check errno).
  67  * note:
  68  *      192.5.5.1/28 has a nonzero host part, which means it isn't a network
  69  *      as called for by inet_net_ntop() but it can be a host address with
  70  *      an included netmask.
  71  * author:
  72  *      Paul Vixie (ISC), October 1998
  73  */
  74 char *
  75 inet_cidr_ntop(int af, const void *src, int bits, char *dst, size_t size) {
  76         switch (af) {
  77         case AF_INET:
  78                 return (inet_cidr_ntop_ipv4(src, bits, dst, size));
  79         case AF_INET6:
  80                 return (inet_cidr_ntop_ipv6(src, bits, dst, size));
  81         default:
  82                 errno = EAFNOSUPPORT;
  83                 return (NULL);
  84         }
  85 }
  86
  87 static int
  88 decoct(const u_char *src, size_t bytes, char *dst, size_t size) {
  89         char *odst = dst;
  90         char *t;
  91         size_t b;
  92
  93         for (b = 1; b <= bytes; b++) {
  94                 if (size < sizeof "255.")
  95                         return (0);
  96                 t = dst;
  97                 dst += SPRINTF((dst, "%u", *src++));
  98                 if (b != bytes) {
  99                         *dst++ = '.';
 100                         *dst = '\0';
 101                 }
 102                 size -= (size_t)(dst - t);
 103         }
 104         return (dst - odst);
 105 }
 106
 107 /*%
 108  * static char *
 109  * inet_cidr_ntop_ipv4(src, bits, dst, size)
 110  *      convert IPv4 network address from network to presentation format.
 111  *      "src"'s size is determined from its "af".
 112  * return:
 113  *      pointer to dst, or NULL if an error occurred (check errno).
 114  * note:
 115  *      network byte order assumed.  this means 192.5.5.240/28 has
 116  *      0b11110000 in its fourth octet.
 117  * author:
 118  *      Paul Vixie (ISC), October 1998
 119  */
 120 static char *
 121 inet_cidr_ntop_ipv4(const u_char *src, int bits, char *dst, size_t size) {
 122         char *odst = dst;
 123         size_t len = 4;
 124         size_t b;
 125         size_t bytes;
 126
 127         if ((bits < -1) || (bits > 32)) {
 128                 errno = EINVAL;
 129                 return (NULL);
 130         }
 131
 132         /* Find number of significant bytes in address. */
 133         if (bits == -1)
 134                 len = 4;
 135         else
 136                 for (len = 1, b = 1 ; b < 4U; b++)
 137                         if (*(src + b))
 138                                 len = b + 1;
 139
 140         /* Format whole octets plus nonzero trailing octets. */
 141         bytes = (((bits <= 0) ? 1 : bits) + 7) / 8;
 142         if (len > bytes)
 143                 bytes = len;
 144         b = decoct(src, bytes, dst, size);
 145         if (b == 0U)
 146                 goto emsgsize;
 147         dst += b;
 148         size -= b;
 149
 150         if (bits != -1) {
 151                 /* Format CIDR /width. */
 152                 if (size < sizeof "/32")
 153                         goto emsgsize;
 154                 dst += SPRINTF((dst, "/%u", bits));
 155         }
 156
 157         return (odst);
 158
 159  emsgsize:
 160         errno = EMSGSIZE;
 161         return (NULL);
 162 }
 163
 164 static char *
 165 inet_cidr_ntop_ipv6(const u_char *src, int bits, char *dst, size_t size) {
 166         /*
 167          * Note that int32_t and int16_t need only be "at least" large enough
 168          * to contain a value of the specified size.  On some systems, like
 169          * Crays, there is no such thing as an integer variable with 16 bits.
 170          * Keep this in mind if you think this function should have been coded
 171          * to use pointer overlays.  All the world's not a VAX.
 172          */
 173         char tmp[sizeof "ffff:ffff:ffff:ffff:ffff:ffff:255.255.255.255/128"];
 174         char *tp;
 175         struct { int base, len; } best, cur;
 176         u_int words[NS_IN6ADDRSZ / NS_INT16SZ];
 177         int i;
 178
 179         if ((bits < -1) || (bits > 128)) {
 180                 errno = EINVAL;
 181                 return (NULL);
 182         }
 183
 184         /*
 185          * Preprocess:
 186          *      Copy the input (bytewise) array into a wordwise array.
 187          *      Find the longest run of 0x00's in src[] for :: shorthanding.
 188          */
 189         memset(words, '\0', sizeof words);
 190         for (i = 0; i < NS_IN6ADDRSZ; i++)
 191                 words[i / 2] |= (src[i] << ((1 - (i % 2)) << 3));
 192         best.base = -1;
 193         best.len = 0;
 194         cur.base = -1;
 195         cur.len = 0;
 196         for (i = 0; i < (NS_IN6ADDRSZ / NS_INT16SZ); i++) {
 197                 if (words[i] == 0) {
 198                         if (cur.base == -1)
 199                                 cur.base = i, cur.len = 1;
 200                         else
 201                                 cur.len++;
 202                 } else {
 203                         if (cur.base != -1) {
 204                                 if (best.base == -1 || cur.len > best.len)
 205                                         best = cur;
 206                                 cur.base = -1;
 207                         }
 208                 }
 209         }
 210         if (cur.base != -1) {
 211                 if (best.base == -1 || cur.len > best.len)
 212                         best = cur;
 213         }
 214         if (best.base != -1 && best.len < 2)
 215                 best.base = -1;
 216
 217         /*
 218          * Format the result.
 219          */
 220         tp = tmp;
 221         for (i = 0; i < (NS_IN6ADDRSZ / NS_INT16SZ); i++) {
 222                 /* Are we inside the best run of 0x00's? */
 223                 if (best.base != -1 && i >= best.base &&
 224                     i < (best.base + best.len)) {
 225                         if (i == best.base)
 226                                 *tp++ = ':';
 227                         continue;
 228                 }
 229                 /* Are we following an initial run of 0x00s or any real hex? */
 230                 if (i != 0)
 231                         *tp++ = ':';
 232                 /* Is this address an encapsulated IPv4? */
 233                 if (i == 6 && best.base == 0 && (best.len == 6 ||
 234                     (best.len == 7 && words[7] != 0x0001) ||
 235                     (best.len == 5 && words[5] == 0xffff))) {
 236                         size_t n;
 237
 238                         if (src[15] || bits == -1 || bits > 120)
 239                                 n = 4;
 240                         else if (src[14] || bits > 112)
 241                                 n = 3;
 242                         else
 243                                 n = 2;
 244                         n = decoct(src+12, n, tp, sizeof tmp - (tp - tmp));
 245                         if (n == 0) {
 246                                 errno = EMSGSIZE;
 247                                 return (NULL);
 248                         }
 249                         tp += strlen(tp);
 250                         break;
 251                 }
 252                 tp += SPRINTF((tp, "%x", words[i]));
 253         }
 254
 255         /* Was it a trailing run of 0x00's? */
 256         if (best.base != -1 && (best.base + best.len) ==
 257             (NS_IN6ADDRSZ / NS_INT16SZ))
 258                 *tp++ = ':';
 259         *tp = '\0';
 260
 261         if (bits != -1)
 262                 tp += SPRINTF((tp, "/%u", bits));
 263
 264         /*
 265          * Check for overflow, copy, and we're done.
 266          */
 267         if ((size_t)(tp - tmp) > size) {
 268                 errno = EMSGSIZE;
 269                 return (NULL);
 270         }
 271         strcpy(dst, tmp);
 272         return (dst);
 273 }
 274
 275 /*! \file */