resolv/inet_net_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 #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 }