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