ethernet.c

open source dhcp server client etc...

/* ethernet.c

   Packet assembly code, originally contributed by Archie Cobbs. */

/*
 * Copyright (c) 1996-2000 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 in cooperation with Vixie Enterprises and Nominum, Inc.
 * To learn more about the Internet Software Consortium, see
 * ``http://www.isc.org/''.  To learn more about Vixie Enterprises,
 * see ``http://www.vix.com''.   To learn more about Nominum, Inc., see
 * ``http://www.nominum.com''.
 */

#ifndef lint
static char copyright[] =
"$Id: ethernet.c,v 1.6.2.1 2001/06/14 19:15:27 mellon Exp $ Copyright (c) 1996-2000 The Internet Software Consortium.  All rights reserved.\n";
#endif /* not lint */

#include "dhcpd.h"

#if defined (PACKET_ASSEMBLY) || defined (PACKET_DECODING)
#include "includes/netinet/if_ether.h"
#endif /* PACKET_ASSEMBLY || PACKET_DECODING */

#if defined (PACKET_ASSEMBLY)
/* Assemble an hardware header... */

void assemble_ethernet_header (interface, buf, bufix, to)
	struct interface_info *interface;
	unsigned char *buf;
	unsigned *bufix;
	struct hardware *to;
{
	struct isc_ether_header eh;

	if (to && to -> hlen == 7) /* XXX */
		memcpy (eh.ether_dhost, &to -> hbuf [1],
			sizeof eh.ether_dhost);
	else
		memset (eh.ether_dhost, 0xff, sizeof (eh.ether_dhost));
	if (interface -> hw_address.hlen - 1 == sizeof (eh.ether_shost))
		memcpy (eh.ether_shost, &interface -> hw_address.hbuf [1],
			sizeof (eh.ether_shost));
	else
		memset (eh.ether_shost, 0x00, sizeof (eh.ether_shost));

	eh.ether_type = htons (ETHERTYPE_IP);

	memcpy (&buf [*bufix], &eh, ETHER_HEADER_SIZE);
	*bufix += ETHER_HEADER_SIZE;
}
#endif /* PACKET_ASSEMBLY */

#ifdef PACKET_DECODING
/* Decode a hardware header... */

ssize_t decode_ethernet_header (interface, buf, bufix, from)
     struct interface_info *interface;
     unsigned char *buf;
     unsigned bufix;
     struct hardware *from;
{
  struct isc_ether_header eh;

  memcpy (&eh, buf + bufix, ETHER_HEADER_SIZE);

#ifdef USERLAND_FILTER
  if (ntohs (eh.ether_type) != ETHERTYPE_IP)
	  return -1;
#endif
  memcpy (&from -> hbuf [1], eh.ether_shost, sizeof (eh.ether_shost));
  from -> hbuf [0] = ARPHRD_ETHER;
  from -> hlen = (sizeof eh.ether_shost) + 1;

  return ETHER_HEADER_SIZE;
}
#endif /* PACKET_DECODING */