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  }