common/ethernet.c

   1 /* ethernet.c
   2
   3    Packet assembly code, originally contributed by Archie Cobbs. */
   4
   5 /*
   6  * Copyright (c) 2004-2017 by Internet Systems Consortium, Inc. ("ISC")
   7  * Copyright (c) 1996-2003 by Internet Software Consortium
   8  *
   9  * This Source Code Form is subject to the terms of the Mozilla Public
  10  * License, v. 2.0. If a copy of the MPL was not distributed with this
  11  * file, You can obtain one at http://mozilla.org/MPL/2.0/.
  12  *
  13  * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES
  14  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
  15  * MERCHANTABILITY AND FITNESS.  IN NO EVENT SHALL ISC BE LIABLE FOR
  16  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
  17  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
  18  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT
  19  * OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  20  *
  21  *   Internet Systems Consortium, Inc.
  22  *   PO Box 360
  23  *   Newmarket, NH 03857 USA
  24  *   <info@isc.org>
  25  *   https://www.isc.org/
  26  *
  27  */
  28
  29 #include "dhcpd.h"
  30
  31 #if defined (PACKET_ASSEMBLY) || defined (PACKET_DECODING)
  32 #include "includes/netinet/if_ether.h"
  33 #endif /* PACKET_ASSEMBLY || PACKET_DECODING */
  34
  35 #if defined (PACKET_ASSEMBLY)
  36 /* Assemble an hardware header... */
  37
  38 void assemble_ethernet_header (interface, buf, bufix, to)
  39         struct interface_info *interface;
  40         unsigned char *buf;
  41         unsigned *bufix;
  42         struct hardware *to;
  43 {
  44         struct isc_ether_header eh;
  45
  46         if (to && to -> hlen == 7) /* XXX */
  47                 memcpy (eh.ether_dhost, &to -> hbuf [1],
  48                         sizeof eh.ether_dhost);
  49         else
  50                 memset (eh.ether_dhost, 0xff, sizeof (eh.ether_dhost));
  51         if (interface -> hw_address.hlen - 1 == sizeof (eh.ether_shost))
  52                 memcpy (eh.ether_shost, &interface -> hw_address.hbuf [1],
  53                         sizeof (eh.ether_shost));
  54         else
  55                 memset (eh.ether_shost, 0x00, sizeof (eh.ether_shost));
  56
  57         eh.ether_type = htons (ETHERTYPE_IP);
  58
  59         memcpy (&buf [*bufix], &eh, ETHER_HEADER_SIZE);
  60         *bufix += ETHER_HEADER_SIZE;
  61 }
  62 #endif /* PACKET_ASSEMBLY */
  63
  64 #ifdef PACKET_DECODING
  65 /* Decode a hardware header... */
  66
  67 ssize_t decode_ethernet_header (interface, buf, bufix, from)
  68      struct interface_info *interface;
  69      unsigned char *buf;
  70      unsigned bufix;
  71      struct hardware *from;
  72 {
  73   struct isc_ether_header eh;
  74
  75   memcpy (&eh, buf + bufix, ETHER_HEADER_SIZE);
  76
  77 #ifdef USERLAND_FILTER
  78   if (ntohs (eh.ether_type) != ETHERTYPE_IP)
  79           return -1;
  80 #endif
  81   memcpy (&from -> hbuf [1], eh.ether_shost, sizeof (eh.ether_shost));
  82   from -> hbuf [0] = ARPHRD_ETHER;
  83   from -> hlen = (sizeof eh.ether_shost) + 1;
  84
  85   return ETHER_HEADER_SIZE;
  86 }
  87 #endif /* PACKET_DECODING */