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 (int af, const void *src, int bits, char *dst, size_t size)
  53 {
  54         switch (af) {
  55         case AF_INET:
  56                 return (inet_net_ntop_ipv4(src, bits, dst, size));
  57         default:
  58                 __set_errno (EAFNOSUPPORT);
  59                 return (NULL);
  60         }
  61 }
  62
  63 /*
  64  * static char *
  65  * inet_net_ntop_ipv4(src, bits, dst, size)
  66  *      convert IPv4 network number from network to presentation format.
  67  *      generates CIDR style result always.
  68  * return:
  69  *      pointer to dst, or NULL if an error occurred (check errno).
  70  * note:
  71  *      network byte order assumed.  this means 192.5.5.240/28 has
  72  *      0b11110000 in its fourth octet.
  73  * author:
  74  *      Paul Vixie (ISC), July 1996
  75  */
  76 static char *
  77 inet_net_ntop_ipv4 (const u_char *src, int bits, char *dst, size_t size)
  78 {
  79         char *odst = dst;
  80         char *t;
  81         u_int m;
  82         int b;
  83
  84         if (bits < 0 || bits > 32) {
  85                 __set_errno (EINVAL);
  86                 return (NULL);
  87         }
  88         if (bits == 0) {
  89                 if (size < sizeof "0")
  90                         goto emsgsize;
  91                 *dst++ = '0';
  92                 size--;
  93                 *dst = '\0';
  94         }
  95
  96         /* Format whole octets. */
  97         for (b = bits / 8; b > 0; b--) {
  98                 if (size < sizeof "255.")
  99                         goto emsgsize;
 100                 t = dst;
 101                 dst += SPRINTF((dst, "%u", *src++));
 102                 if (b > 1) {
 103                         *dst++ = '.';
 104                         *dst = '\0';
 105                 }
 106                 size -= (size_t)(dst - t);
 107         }
 108
 109         /* Format partial octet. */
 110         b = bits % 8;
 111         if (b > 0) {
 112                 if (size < sizeof ".255")
 113                         goto emsgsize;
 114                 t = dst;
 115                 if (dst != odst)
 116                         *dst++ = '.';
 117                 m = ((1 << b) - 1) << (8 - b);
 118                 dst += SPRINTF((dst, "%u", *src & m));
 119                 size -= (size_t)(dst - t);
 120         }
 121
 122         /* Format CIDR /width. */
 123         if (size < sizeof "/32")
 124                 goto emsgsize;
 125         dst += SPRINTF((dst, "/%u", bits));
 126         return (odst);
 127
 128  emsgsize:
 129         __set_errno (EMSGSIZE);
 130         return (NULL);
 131 }