text: /* inet.c
  
     Subroutines to manipulate internet addresses in a safely portable
     way... */
  
  /*
   * Copyright (c) 1996 The Internet Software Consortium.  All rights reserved.
   *
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted provided that the following conditions
   * are met:
   *
   * 1. Redistributions of source code must retain the above copyright
   *    notice, this list of conditions and the following disclaimer.
   * 2. Redistributions in binary form must reproduce the above copyright
   *    notice, this list of conditions and the following disclaimer in the
   *    documentation and/or other materials provided with the distribution.
   * 3. Neither the name of The Internet Software Consortium nor the names
   *    of its contributors may be used to endorse or promote products derived
   *    from this software without specific prior written permission.
   *
   * THIS SOFTWARE IS PROVIDED BY THE INTERNET SOFTWARE CONSORTIUM AND
   * CONTRIBUTORS ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES,
   * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
   * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
   * DISCLAIMED.  IN NO EVENT SHALL THE INTERNET SOFTWARE CONSORTIUM OR
   * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
   * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
   * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
   * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
   * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
   * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
   * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   * SUCH DAMAGE.
   *
   * This software has been written for the Internet Software Consortium
   * by Ted Lemon <mellon@fugue.com> in cooperation with Vixie
   * Enterprises.  To learn more about the Internet Software Consortium,
   * see ``http://www.vix.com/isc''.  To learn more about Vixie
   * Enterprises, see ``http://www.vix.com''.
   */
  
  #include "dhcpd.h"
  
  /* Return just the network number of an internet address... */
  
  struct iaddr subnet_number (addr, mask)
  	struct iaddr addr;
  	struct iaddr mask;
  {
  	int i;
  	struct iaddr rv;
  
  	rv.len = 0;
  
  	/* Both addresses must have the same length... */
  	if (addr.len != mask.len)
  		return rv;
  
  	rv.len = addr.len;
  	for (i = 0; i < rv.len; i++)
  		rv.iabuf [i] = addr.iabuf [i] & mask.iabuf [i];
  	return rv;
  }
  
  /* Combine a network number and a integer to produce an internet address.
     This won't work for subnets with more than 32 bits of host address, but
     maybe this isn't a problem. */
  
  struct iaddr ip_addr (subnet, mask, host_address)
  	struct iaddr subnet;
  	struct iaddr mask;
  	u_int32_t host_address;
  {
  	int i, j, k;
  	u_int32_t swaddr;
  	struct iaddr rv;
  	unsigned char habuf [sizeof swaddr];
  
  	swaddr = htonl (host_address);
  	memcpy (habuf, &swaddr, sizeof swaddr);
  
  	/* Combine the subnet address and the host address.   If
  	   the host address is bigger than can fit in the subnet,
  	   return a zero-length iaddr structure. */
  	rv = subnet;
  	j = rv.len - sizeof habuf;
  	for (i = sizeof habuf - 1; i >= 0; i--) {
  		if (mask.iabuf [i + j]) {
  			if (habuf [i] > (mask.iabuf [i + j] ^ 0xFF)) {
  				rv.len = 0;
  				return rv;
  			}
  			for (k = i - 1; k >= 0; k--) {
  				if (habuf [k]) {
  					rv.len = 0;
  					return rv;
  				}
  			}
  			rv.iabuf [i + j] |= habuf [i];
  			break;
  		} else
  			rv.iabuf [i + j] = habuf [i];
  	}
  		
  	return rv;
  }
  
  /* Given a subnet number and netmask, return the address on that subnet
     for which the host portion of the address is all ones (the standard
     broadcast address). */
  
  struct iaddr broadcast_addr (subnet, mask)
  	struct iaddr subnet;
  	struct iaddr mask;
  {
  	int i, j, k;
  	struct iaddr rv;
  
  	if (subnet.len != mask.len) {
  		rv.len = 0;
  		return rv;
  	}
  
  	for (i = 0; i < subnet.len; i++) {
  		rv.iabuf [i] = subnet.iabuf [i] | (~mask.iabuf [i] & 255);
  	}
  	rv.len = subnet.len;
  
  	return rv;
  }
  
  u_int32_t host_addr (addr, mask)
  	struct iaddr addr;
  	struct iaddr mask;
  {
  	int i;
  	u_int32_t swaddr;
  	struct iaddr rv;
  
  	rv.len = 0;
  
  	/* Mask out the network bits... */
  	rv.len = addr.len;
  	for (i = 0; i < rv.len; i++)
  		rv.iabuf [i] = addr.iabuf [i] & ~mask.iabuf [i];
  
  	/* Copy out up to 32 bits... */
  	memcpy (&swaddr, &rv.iabuf [rv.len - sizeof swaddr], sizeof swaddr);
  
  	/* Swap it and return it. */
  	return ntohl (swaddr);
  }
  
  int addr_eq (addr1, addr2)
  	struct iaddr addr1, addr2;
  {
  	if (addr1.len != addr2.len)
  		return 0;
  	return memcmp (addr1.iabuf, addr2.iabuf, addr1.len) == 0;
  }
  
  char *piaddr (addr)
  	struct iaddr addr;
  {
  	static char pbuf [4 * 16];
  	char *s = pbuf;
  	int i;
  
  	if (addr.len == 0) {
  		strcpy (s, "<null address>");
  	}
  	for (i = 0; i < addr.len; i++) {
  		sprintf (s, "%s%d", i ? "." : "", addr.iabuf [i]);
  		s += strlen (s);
  	}
  	return pbuf;
  }
  