/* packet-eth.c
 * Routines for ethernet packet disassembly
 *
 * $Id: packet-eth.c,v 1.53 2001/01/03 10:34:41 guy Exp $
 *
 * Ethereal - Network traffic analyzer
 * By Gerald Combs <gerald@zing.org>
 * Copyright 1998 Gerald Combs
 *
 * 
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 * 
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
 */

#ifdef HAVE_CONFIG_H
# include "config.h"
#endif

#ifdef HAVE_SYS_TYPES_H
# include <sys/types.h>
#endif

#include <glib.h>
#include "packet.h"
#include "etypes.h"
#include "resolv.h"
#include "packet-eth.h"
#include "packet-ipx.h"
#include "packet-isl.h"
#include "packet-llc.h"

extern const value_string etype_vals[];

/* protocols and header fields */
static int proto_eth = -1;
static int hf_eth_dst = -1;
static int hf_eth_src = -1;
static int hf_eth_len = -1;
static int hf_eth_type = -1;
static int hf_eth_addr = -1;
static int hf_eth_trailer = -1;

static gint ett_ieee8023 = -1;
static gint ett_ether2 = -1;

static dissector_handle_t isl_handle;
static dissector_handle_t llc_handle;

#define ETH_HEADER_SIZE	14

/* These are the Netware-ish names for the different Ethernet frame types.
	EthernetII: The ethernet with a Type field instead of a length field
	Ethernet802.2: An 802.3 header followed by an 802.2 header
	Ethernet802.3: A raw 802.3 packet. IPX/SPX can be the only payload.
			There's no 802.2 hdr in this.
	EthernetSNAP: Basically 802.2, just with 802.2SNAP. For our purposes,
		there's no difference between 802.2 and 802.2SNAP, since we just
		pass it down to the LLC dissector. -- Gilbert
*/
#define ETHERNET_II 	0
#define ETHERNET_802_2	1
#define ETHERNET_802_3	2
#define ETHERNET_SNAP	3

void
capture_eth(const u_char *pd, int offset, packet_counts *ld)
{
  guint16    etype, length;
  int     ethhdr_type;	/* the type of ethernet frame */

  if (!BYTES_ARE_IN_FRAME(offset, ETH_HEADER_SIZE)) {
    ld->other++;
    return;
  }
  
  etype = pntohs(&pd[offset+12]);

	/* either ethernet802.3 or ethernet802.2 */
  if (etype <= IEEE_802_3_MAX_LEN) {
    length = etype;

    /* Is there an 802.2 layer? I can tell by looking at the first 2
       bytes after the 802.3 header. If they are 0xffff, then what
       follows the 802.3 header is an IPX payload, meaning no 802.2.
       (IPX/SPX is they only thing that can be contained inside a
       straight 802.3 packet). A non-0xffff value means that there's an
       802.2 layer inside the 802.3 layer */
    if (pd[offset+14] == 0xff && pd[offset+15] == 0xff) {
      ethhdr_type = ETHERNET_802_3;
    }
    else {
      ethhdr_type = ETHERNET_802_2;
    }

    /* Oh, yuck.  Cisco ISL frames require special interpretation of the
       destination address field; fortunately, they can be recognized by
       checking the first 5 octets of the destination address, which are
       01-00-0C-00-00 for ISL frames. */
    if (pd[offset] == 0x01 && pd[offset+1] == 0x00 && pd[offset+2] == 0x0C
	&& pd[offset+3] == 0x00 && pd[offset+4] == 0x00) {
      capture_isl(pd, offset, ld);
      return;
    }

    /* Convert the LLC length from the 802.3 header to a total
       frame length, by adding in the size of any data that preceded
       the Ethernet header, and adding in the Ethernet header size,
       and set the payload and captured-payload lengths to the minima
       of the total length and the frame lengths. */
    length += offset + ETH_HEADER_SIZE;
    if (pi.len > length)
      pi.len = length;
    if (pi.captured_len > length)
      pi.captured_len = length;
  } else {
    ethhdr_type = ETHERNET_II;
  }
  offset += ETH_HEADER_SIZE;

  switch (ethhdr_type) {
    case ETHERNET_802_3:
      capture_ipx(pd, offset, ld);
      break;
    case ETHERNET_802_2:
      capture_llc(pd, offset, ld);
      break;
    case ETHERNET_II:
      capture_ethertype(etype, offset, pd, ld);
      break;
  }
}

void
dissect_eth(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
{
  int        		orig_captured_len;
  proto_item		*ti;
  guint8		*dst, *src;
  const guint8		*pd;

  volatile guint16	etype;
  volatile int		ethhdr_type;	/* the type of Ethernet frame */
  volatile int		eth_offset;
  volatile guint16  	length;
  tvbuff_t		*volatile next_tvb;
  tvbuff_t		*volatile trailer_tvb;
  proto_tree		*volatile fh_tree;
  guint			length_before;

  CHECK_DISPLAY_AS_DATA(proto_eth, tvb, pinfo, tree);

  tvb_compat(tvb, &pd, (int*)&eth_offset);

  pinfo->current_proto = "Ethernet";
  orig_captured_len = pinfo->captured_len;

  if (check_col(pinfo->fd, COL_PROTOCOL))
    col_set_str(pinfo->fd, COL_PROTOCOL, "Ethernet");

  src = tvb_get_ptr(tvb, 6, 6);
  dst = tvb_get_ptr(tvb, 0, 6);
  SET_ADDRESS(&pinfo->dl_src,	AT_ETHER, 6, src);
  SET_ADDRESS(&pinfo->src,	AT_ETHER, 6, src);
  SET_ADDRESS(&pinfo->dl_dst,	AT_ETHER, 6, dst);
  SET_ADDRESS(&pinfo->dst,	AT_ETHER, 6, dst);

  etype = tvb_get_ntohs(tvb, 12);

	/* either ethernet802.3 or ethernet802.2 */
  if (etype <= IEEE_802_3_MAX_LEN) {
    length = etype;

    /* Is there an 802.2 layer? I can tell by looking at the first 2
       bytes after the 802.3 header. If they are 0xffff, then what
       follows the 802.3 header is an IPX payload, meaning no 802.2.
       (IPX/SPX is they only thing that can be contained inside a
       straight 802.3 packet). A non-0xffff value means that there's an
       802.2 layer inside the 802.3 layer */
    ethhdr_type = ETHERNET_802_2;
    TRY {
	    if (tvb_get_ntohs(tvb, 14) == 0xffff) {
	      ethhdr_type = ETHERNET_802_3;
	    }
    }
    CATCH2(BoundsError, ReportedBoundsError) {
	    ; /* do nothing */

    }
    ENDTRY;

    /* Oh, yuck.  Cisco ISL frames require special interpretation of the
       destination address field; fortunately, they can be recognized by
       checking the first 5 octets of the destination address, which are
       01-00-0C-00-00 for ISL frames. */
    if (	tvb_get_guint8(tvb, 0) == 0x01 &&
		tvb_get_guint8(tvb, 1) == 0x00 &&
		tvb_get_guint8(tvb, 2) == 0x0C &&
		tvb_get_guint8(tvb, 3) == 0x00 &&
		tvb_get_guint8(tvb, 4) == 0x00 ) {
      call_dissector(isl_handle, tvb, pinfo, tree);
      return;
    }

    if (check_col(pinfo->fd, COL_INFO)) {
      col_add_fstr(pinfo->fd, COL_INFO, "IEEE 802.3 %s",
		(ethhdr_type == ETHERNET_802_3 ? "Raw " : ""));
    }
    if (tree) {

	ti = proto_tree_add_protocol_format(tree, proto_eth, tvb, 0, ETH_HEADER_SIZE,
		"IEEE 802.3 %s", (ethhdr_type == ETHERNET_802_3 ? "Raw " : ""));

	fh_tree = proto_item_add_subtree(ti, ett_ieee8023);

	proto_tree_add_ether(fh_tree, hf_eth_dst, tvb, 0, 6, dst);
	proto_tree_add_ether(fh_tree, hf_eth_src, tvb, 6, 6, src);

/* add items for eth.addr filter */
	proto_tree_add_ether_hidden(fh_tree, hf_eth_addr, tvb, 0, 6, dst);
	proto_tree_add_ether_hidden(fh_tree, hf_eth_addr, tvb, 6, 6, src);

	proto_tree_add_uint(fh_tree, hf_eth_len, tvb, 12, 2, length);
    }

    /* Convert the LLC length from the 802.3 header to a total
       frame length, by adding in the size of any data that preceded
       the Ethernet header, and adding in the Ethernet header size,
       and set the payload and captured-payload lengths to the minima
       of the total length and the frame lengths.

       XXX - when all dissectors are tvbuffified we shouldn't have to
       do this any more. */
    length += eth_offset + ETH_HEADER_SIZE;
    if (pinfo->len > length)
      pinfo->len = length;
    if (pinfo->captured_len > length)
      pinfo->captured_len = length;
  } else {
    ethhdr_type = ETHERNET_II;
    if (check_col(pinfo->fd, COL_INFO))
      col_set_str(pinfo->fd, COL_INFO, "Ethernet II");
    if (tree) {

	ti = proto_tree_add_protocol_format(tree, proto_eth, tvb, 0, ETH_HEADER_SIZE,
		"Ethernet II");

	fh_tree = proto_item_add_subtree(ti, ett_ether2);

	proto_tree_add_ether(fh_tree, hf_eth_dst, tvb, 0, 6, dst);
	proto_tree_add_ether(fh_tree, hf_eth_src, tvb, 6, 6, src);
/* add items for eth.addr filter */
	proto_tree_add_ether_hidden(fh_tree, hf_eth_addr, tvb, 0, 6, dst);
	proto_tree_add_ether_hidden(fh_tree, hf_eth_addr, tvb, 6, 6, src);
    }
  }
  eth_offset += ETH_HEADER_SIZE;

  if (etype <= IEEE_802_3_MAX_LEN) {
	  /* Give the next dissector only 'length' number of bytes */
	  TRY {
	    next_tvb = tvb_new_subset(tvb, ETH_HEADER_SIZE, etype, etype);
	    trailer_tvb = tvb_new_subset(tvb, ETH_HEADER_SIZE + etype, -1, -1);
	  }
	  CATCH2(BoundsError, ReportedBoundsError) {
	    /* Either:

		 the packet doesn't have "etype" bytes worth of
		 captured data left in it - or it may not even have
		 "etype" bytes worth of data in it, period -
		 so the "tvb_new_subset()" creating "next_tvb"
		 threw an exception

	       or

		 the packet has exactly "etype" bytes worth of
		 captured data left in it, so the "tvb_new_subset()"
		 creating "trailer_tvb" threw an exception.

	      In either case, this means that all the data in the frame
	      is within the length value, so we give all the data to the
	      next protocol and have no trailer. */
	    next_tvb = tvb_new_subset(tvb, ETH_HEADER_SIZE, -1, etype);
	    trailer_tvb = NULL;
	  }
	  ENDTRY;
  }
  else {
     next_tvb = NULL;	/* "ethertype()" will create the next tvb for us */
     trailer_tvb = NULL;	/* we don't know how big the trailer is */
  }

  switch (ethhdr_type) {
    case ETHERNET_802_3:
      dissect_ipx(next_tvb, pinfo, tree);
      break;
    case ETHERNET_802_2:
      call_dissector(llc_handle, next_tvb, pinfo, tree);
      break;
    case ETHERNET_II:
      length_before = tvb_reported_length(tvb);
      length = ethertype(etype, tvb, ETH_HEADER_SIZE, pinfo, tree, fh_tree,
          hf_eth_type) + ETH_HEADER_SIZE;
      if (length < length_before) {
	/*
	 * Create a tvbuff for the padding.
	 */
	TRY {
	  trailer_tvb = tvb_new_subset(tvb, length, -1, -1);
	}
	CATCH2(BoundsError, ReportedBoundsError) {
	  /* The packet doesn't have "length" bytes worth of captured
	     data left in it.  No trailer to display. */
	  trailer_tvb = NULL;
	}
	ENDTRY;
      }
      break;
  }

  /* If there's some bytes left over, mark them. */
  if (trailer_tvb && tree) {
	  guint           trailer_length;

	  trailer_length = tvb_length(trailer_tvb);
	  if (trailer_length != 0) {
		  proto_tree_add_item(fh_tree, hf_eth_trailer, trailer_tvb, 0,
			  trailer_length, FALSE);
	  }
  }

}

void
proto_register_eth(void)
{
	static hf_register_info hf[] = {

		{ &hf_eth_dst,
		{ "Destination",	"eth.dst", FT_ETHER, BASE_NONE, NULL, 0x0,
			"Destination Hardware Address" }},

		{ &hf_eth_src,
		{ "Source",		"eth.src", FT_ETHER, BASE_NONE, NULL, 0x0,
			"Source Hardware Address" }},

		{ &hf_eth_len,
		{ "Length",		"eth.len", FT_UINT16, BASE_DEC, NULL, 0x0,
			"" }},

		/* registered here but handled in ethertype.c */
		{ &hf_eth_type,
		{ "Type",		"eth.type", FT_UINT16, BASE_HEX, VALS(etype_vals), 0x0,
			"" }},
		{ &hf_eth_addr,
		{ "Source or Destination Address", "eth.addr", FT_ETHER, BASE_NONE, NULL, 0x0,
			"Source or Destination Hardware Address" }},

                { &hf_eth_trailer,
		{ "Trailer", "eth.trailer", FT_BYTES, BASE_NONE, NULL, 0x0,
			"Ethernet Trailer or Checksum" }},

	};
	static gint *ett[] = {
		&ett_ieee8023,
		&ett_ether2,
	};

	proto_eth = proto_register_protocol("Ethernet", "Ethernet", "eth");
	proto_register_field_array(proto_eth, hf, array_length(hf));
	proto_register_subtree_array(ett, array_length(ett));

	register_dissector("eth", dissect_eth);
}

void
proto_reg_handoff_eth(void)
{
	/*
	 * Get handles for the ISL and LLC dissectors.
	 */
	isl_handle = find_dissector("isl");
	llc_handle = find_dissector("llc");

	dissector_add("wtap_encap", WTAP_ENCAP_ETHERNET, dissect_eth);
}