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: #if defined(LIBC_SCCS) && !defined(lint)
   19: static const char rcsid[] = "$BINDId: inet_net_ntop.c,v 1.6 1999/01/08 19:23:42 vixie Exp $";
   20: #endif
   21: 
   22: #include <sys/types.h>
   23: #include <sys/socket.h>
   24: #include <netinet/in.h>
   25: #include <arpa/inet.h>
   26: 
   27: #include <errno.h>
   28: #include <stdio.h>
   29: #include <string.h>
   30: #include <stdlib.h>
   31: 
   32: #ifdef SPRINTF_CHAR
   33: # define SPRINTF(x) strlen(sprintf/**/x)
   34: #else
   35: # define SPRINTF(x) ((size_t)sprintf x)
   36: #endif
   37: 
   38: static char *   inet_net_ntop_ipv4 (const u_char *src, int bits,
   39:                                     char *dst, size_t size) __THROW;
   40: 
   41: /*
   42:  * char *
   43:  * inet_net_ntop(af, src, bits, dst, size)
   44:  *      convert network number from network to presentation format.
   45:  *      generates CIDR style result always.
   46:  * return:
   47:  *      pointer to dst, or NULL if an error occurred (check errno).
   48:  * author:
   49:  *      Paul Vixie (ISC), July 1996
   50:  */
   51: char *
   52: inet_net_ntop(af, src, bits, dst, size)
   53:         int af;
   54:         const void *src;
   55:         int bits;
   56:         char *dst;
   57:         size_t size;
   58: {
   59:         switch (af) {
   60:         case AF_INET:
   61:                 return (inet_net_ntop_ipv4(src, bits, dst, size));
   62:         default:
   63:                 __set_errno (EAFNOSUPPORT);
   64:                 return (NULL);
   65:         }
   66: }
   67: 
   68: /*
   69:  * static char *
   70:  * inet_net_ntop_ipv4(src, bits, dst, size)
   71:  *      convert IPv4 network number from network to presentation format.
   72:  *      generates CIDR style result always.
   73:  * return:
   74:  *      pointer to dst, or NULL if an error occurred (check errno).
   75:  * note:
   76:  *      network byte order assumed.  this means 192.5.5.240/28 has
   77:  *      0b11110000 in its fourth octet.
   78:  * author:
   79:  *      Paul Vixie (ISC), July 1996
   80:  */
   81: static char *
   82: inet_net_ntop_ipv4(src, bits, dst, size)
   83:         const u_char *src;
   84:         int bits;
   85:         char *dst;
   86:         size_t size;
   87: {
   88:         char *odst = dst;
   89:         char *t;
   90:         u_int m;
   91:         int b;
   92: 
   93:         if (bits < 0 || bits > 32) {
   94:                 __set_errno (EINVAL);
   95:                 return (NULL);
   96:         }
   97:         if (bits == 0) {
   98:                 if (size < sizeof "0")
   99:                         goto emsgsize;
  100:                 *dst++ = '0';
  101:                 size--;
  102:                 *dst = '\0';
  103:         }
  104: 
  105:         /* Format whole octets. */
  106:         for (b = bits / 8; b > 0; b--) {
  107:                 if (size < sizeof "255.")
  108:                         goto emsgsize;
  109:                 t = dst;
  110:                 dst += SPRINTF((dst, "%u", *src++));
  111:                 if (b > 1) {
  112:                         *dst++ = '.';
  113:                         *dst = '\0';
  114:                 }
  115:                 size -= (size_t)(dst - t);
  116:         }
  117: 
  118:         /* Format partial octet. */
  119:         b = bits % 8;
  120:         if (b > 0) {
  121:                 if (size < sizeof ".255")
  122:                         goto emsgsize;
  123:                 t = dst;
  124:                 if (dst != odst)
  125:                         *dst++ = '.';
  126:                 m = ((1 << b) - 1) << (8 - b);
  127:                 dst += SPRINTF((dst, "%u", *src & m));
  128:                 size -= (size_t)(dst - t);
  129:         }
  130: 
  131:         /* Format CIDR /width. */
  132:         if (size < sizeof "/32")
  133:                 goto emsgsize;
  134:         dst += SPRINTF((dst, "/%u", bits));
  135:         return (odst);
  136: 
  137:  emsgsize:
  138:         __set_errno (EMSGSIZE);
  139:         return (NULL);
  140: }