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      1 /*	$NetBSD: ethernet.c,v 1.3 2022/04/03 01:10:58 christos Exp $	*/
      2 
      3 /* ethernet.c
      4 
      5    Packet assembly code, originally contributed by Archie Cobbs. */
      6 
      7 /*
      8  * Copyright (C) 2004-2022 Internet Systems Consortium, Inc. ("ISC")
      9  * Copyright (c) 1996-2003 by Internet Software Consortium
     10  *
     11  * This Source Code Form is subject to the terms of the Mozilla Public
     12  * License, v. 2.0. If a copy of the MPL was not distributed with this
     13  * file, You can obtain one at http://mozilla.org/MPL/2.0/.
     14  *
     15  * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES
     16  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
     17  * MERCHANTABILITY AND FITNESS.  IN NO EVENT SHALL ISC BE LIABLE FOR
     18  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
     19  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
     20  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT
     21  * OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
     22  *
     23  *   Internet Systems Consortium, Inc.
     24  *   PO Box 360
     25  *   Newmarket, NH 03857 USA
     26  *   <info (at) isc.org>
     27  *   https://www.isc.org/
     28  *
     29  */
     30 
     31 #include <sys/cdefs.h>
     32 __RCSID("$NetBSD: ethernet.c,v 1.3 2022/04/03 01:10:58 christos Exp $");
     33 
     34 #include "dhcpd.h"
     35 
     36 #if defined (PACKET_ASSEMBLY) || defined (PACKET_DECODING)
     37 #include "includes/netinet/if_ether.h"
     38 #endif /* PACKET_ASSEMBLY || PACKET_DECODING */
     39 
     40 #if defined (PACKET_ASSEMBLY)
     41 /* Assemble an hardware header... */
     42 
     43 void assemble_ethernet_header (interface, buf, bufix, to)
     44 	struct interface_info *interface;
     45 	unsigned char *buf;
     46 	unsigned *bufix;
     47 	struct hardware *to;
     48 {
     49 	struct isc_ether_header eh;
     50 
     51 	if (to && to -> hlen == 7) /* XXX */
     52 		memcpy (eh.ether_dhost, &to -> hbuf [1],
     53 			sizeof eh.ether_dhost);
     54 	else
     55 		memset (eh.ether_dhost, 0xff, sizeof (eh.ether_dhost));
     56 	if (interface -> hw_address.hlen - 1 == sizeof (eh.ether_shost))
     57 		memcpy (eh.ether_shost, &interface -> hw_address.hbuf [1],
     58 			sizeof (eh.ether_shost));
     59 	else
     60 		memset (eh.ether_shost, 0x00, sizeof (eh.ether_shost));
     61 
     62 	eh.ether_type = htons (ETHERTYPE_IP);
     63 
     64 	memcpy (&buf [*bufix], &eh, ETHER_HEADER_SIZE);
     65 	*bufix += ETHER_HEADER_SIZE;
     66 }
     67 #endif /* PACKET_ASSEMBLY */
     68 
     69 #ifdef PACKET_DECODING
     70 /* Decode a hardware header... */
     71 
     72 ssize_t decode_ethernet_header (interface, buf, bufix, from)
     73      struct interface_info *interface;
     74      unsigned char *buf;
     75      unsigned bufix;
     76      struct hardware *from;
     77 {
     78   struct isc_ether_header eh;
     79 
     80   memcpy (&eh, buf + bufix, ETHER_HEADER_SIZE);
     81 
     82 #ifdef USERLAND_FILTER
     83   if (ntohs (eh.ether_type) != ETHERTYPE_IP)
     84 	  return -1;
     85 #endif
     86   memcpy (&from -> hbuf [1], eh.ether_shost, sizeof (eh.ether_shost));
     87   from -> hbuf [0] = ARPHRD_ETHER;
     88   from -> hlen = (sizeof eh.ether_shost) + 1;
     89 
     90   return ETHER_HEADER_SIZE;
     91 }
     92 #endif /* PACKET_DECODING */
     93