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wireshark/packet-eth.c

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/* packet-eth.c
* Routines for ethernet packet disassembly
*
* $Id: packet-eth.c,v 1.89 2004/02/03 23:19:54 guy Exp $
*
* Ethereal - Network traffic analyzer
* By Gerald Combs <gerald@ethereal.com>
* 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
#include <glib.h>
#include <epan/packet.h>
#include "prefs.h"
#include "etypes.h"
#include <epan/resolv.h>
#include "packet-eth.h"
#include "packet-ieee8023.h"
#include "packet-ipx.h"
#include "packet-isl.h"
#include "packet-llc.h"
#include "crc32.h"
#include "tap.h"
/* Interpret capture file as FW1 monitor file */
static gboolean eth_interpret_as_fw1_monitor = FALSE;
/* 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 fw1_handle;
static heur_dissector_list_t heur_subdissector_list;
static int eth_tap = -1;
#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 guchar *pd, int offset, int len, packet_counts *ld)
{
guint16 etype, length;
int ethhdr_type; /* the type of ethernet frame */
if (!BYTES_ARE_IN_FRAME(offset, len, ETH_HEADER_SIZE)) {
ld->other++;
return;
}
etype = pntohs(&pd[offset+12]);
/*
* If the type/length field is <= the maximum 802.3 length,
* and is not zero, this is an 802.3 frame, and it's a length
* field; it might be an Novell "raw 802.3" frame, with no
* 802.2 LLC header, or it might be a frame with an 802.2 LLC
* header.
*
* If the type/length field is > the maximum 802.3 length,
* this is an Ethernet II frame, and it's a type field.
*
* If the type/length field is zero (ETHERTYPE_UNK), this is
* a frame used internally by the Cisco MDS switch to contain
* Fibre Channel ("Vegas"). We treat that as an Ethernet II
* frame; the dissector for those frames registers itself with
* an ethernet type of ETHERTYPE_UNK.
*/
if (etype <= IEEE_802_3_MAX_LEN && etype != ETHERTYPE_UNK) {
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, len, 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 (len > length)
len = length;
} else {
ethhdr_type = ETHERNET_II;
}
offset += ETH_HEADER_SIZE;
switch (ethhdr_type) {
case ETHERNET_802_3:
capture_ipx(ld);
break;
case ETHERNET_802_2:
capture_llc(pd, offset, len, ld);
break;
case ETHERNET_II:
capture_ethertype(etype, pd, offset, len, ld);
break;
}
}
static void
dissect_eth_common(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree,
int fcs_len)
{
proto_item *ti;
eth_hdr *ehdr;
volatile gboolean is_802_2;
proto_tree *volatile fh_tree = NULL;
const char *src_addr, *dst_addr;
static eth_hdr ehdrs[4];
static int ehdr_num=0;
ehdr_num++;
if(ehdr_num>=4){
ehdr_num=0;
}
ehdr=&ehdrs[ehdr_num];
if (check_col(pinfo->cinfo, COL_PROTOCOL))
col_set_str(pinfo->cinfo, COL_PROTOCOL, "Ethernet");
src_addr=tvb_get_ptr(tvb, 6, 6);
SET_ADDRESS(&pinfo->dl_src, AT_ETHER, 6, src_addr);
SET_ADDRESS(&pinfo->src, AT_ETHER, 6, src_addr);
SET_ADDRESS(&ehdr->src, AT_ETHER, 6, src_addr);
dst_addr=tvb_get_ptr(tvb, 0, 6);
SET_ADDRESS(&pinfo->dl_dst, AT_ETHER, 6, dst_addr);
SET_ADDRESS(&pinfo->dst, AT_ETHER, 6, dst_addr);
SET_ADDRESS(&ehdr->dst, AT_ETHER, 6, dst_addr);
ehdr->type = tvb_get_ntohs(tvb, 12);
/*
* In case the packet is a non-Ethernet packet inside
* Ethernet framing, allow heuristic dissectors to take
* a first look before we assume that it's actually an
* Ethernet packet.
*/
if (dissector_try_heuristic(heur_subdissector_list, tvb, pinfo, tree))
goto end_of_eth;
/*
* If the type/length field is <= the maximum 802.3 length,
* and is not zero, this is an 802.3 frame, and it's a length
* field; it might be an Novell "raw 802.3" frame, with no
* 802.2 LLC header, or it might be a frame with an 802.2 LLC
* header.
*
* If the type/length field is > the maximum 802.3 length,
* this is an Ethernet II frame, and it's a type field.
*
* If the type/length field is zero (ETHERTYPE_UNK), this is
* a frame used internally by the Cisco MDS switch to contain
* Fibre Channel ("Vegas"). We treat that as an Ethernet II
* frame; the dissector for those frames registers itself with
* an ethernet type of ETHERTYPE_UNK.
*/
if (ehdr->type <= IEEE_802_3_MAX_LEN && ehdr->type != ETHERTYPE_UNK) {
/* 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);
goto end_of_eth;
}
/* 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 */
is_802_2 = TRUE;
TRY {
if (tvb_get_ntohs(tvb, 14) == 0xffff) {
is_802_2 = FALSE;
}
}
CATCH2(BoundsError, ReportedBoundsError) {
; /* do nothing */
}
ENDTRY;
if (check_col(pinfo->cinfo, COL_INFO)) {
col_add_fstr(pinfo->cinfo, COL_INFO, "IEEE 802.3 Ethernet %s",
(is_802_2 ? "" : "Raw "));
}
if (tree) {
ti = proto_tree_add_protocol_format(tree, proto_eth, tvb, 0, ETH_HEADER_SIZE,
"IEEE 802.3 Ethernet %s", (is_802_2 ? "" : "Raw "));
fh_tree = proto_item_add_subtree(ti, ett_ieee8023);
}
proto_tree_add_ether(fh_tree, hf_eth_dst, tvb, 0, 6, dst_addr);
proto_tree_add_ether(fh_tree, hf_eth_src, tvb, 6, 6, src_addr);
/* add items for eth.addr filter */
proto_tree_add_ether_hidden(fh_tree, hf_eth_addr, tvb, 0, 6, dst_addr);
proto_tree_add_ether_hidden(fh_tree, hf_eth_addr, tvb, 6, 6, src_addr);
dissect_802_3(ehdr->type, is_802_2, tvb, ETH_HEADER_SIZE, pinfo, tree, fh_tree,
hf_eth_len, hf_eth_trailer, fcs_len);
} else {
if (eth_interpret_as_fw1_monitor) {
call_dissector(fw1_handle, tvb, pinfo, tree);
goto end_of_eth;
}
if (check_col(pinfo->cinfo, COL_INFO))
col_set_str(pinfo->cinfo, COL_INFO, "Ethernet II");
if (tree) {
ti = proto_tree_add_protocol_format(tree, proto_eth, tvb, 0, ETH_HEADER_SIZE,
"Ethernet II, Src: %s, Dst: %s",
ether_to_str(src_addr), ether_to_str(dst_addr));
fh_tree = proto_item_add_subtree(ti, ett_ether2);
}
proto_tree_add_ether(fh_tree, hf_eth_dst, tvb, 0, 6, dst_addr);
proto_tree_add_ether(fh_tree, hf_eth_src, tvb, 6, 6, src_addr);
/* add items for eth.addr filter */
proto_tree_add_ether_hidden(fh_tree, hf_eth_addr, tvb, 0, 6, dst_addr);
proto_tree_add_ether_hidden(fh_tree, hf_eth_addr, tvb, 6, 6, src_addr);
ethertype(ehdr->type, tvb, ETH_HEADER_SIZE, pinfo, tree, fh_tree, hf_eth_type,
hf_eth_trailer, fcs_len);
}
end_of_eth:
tap_queue_packet(eth_tap, pinfo, ehdr);
return;
}
/*
* Add an Ethernet trailer - which, for some captures, might be the FCS
* rather than a pad-to-60-bytes trailer.
*
* If fcs_len is 0, we assume the frame has no FCS; if it's 4, we assume
* it has an FCS; if it's anything else (such as -1, which means "maybe
* it does, maybe it doesn't"), we try to infer whether it has an FCS.
*/
void
add_ethernet_trailer(proto_tree *fh_tree, int trailer_id, tvbuff_t *tvb,
tvbuff_t *trailer_tvb, int fcs_len)
{
/* If there're some bytes left over, show those bytes as a trailer.
However, if the Ethernet frame was claimed to have had 64 or more
bytes - i.e., it was at least an FCS worth of data longer than
the minimum payload size - assume the last 4 bytes of the trailer
are an FCS. */
if (trailer_tvb && fh_tree) {
guint trailer_length, trailer_reported_length;
gboolean has_fcs = FALSE;
trailer_length = tvb_length(trailer_tvb);
trailer_reported_length = tvb_reported_length(trailer_tvb);
if (fcs_len != 0) {
/* If fcs_len is 4, we assume we definitely have an FCS.
Otherwise, then, if the frame is big enough that, if we
have a trailer, it probably inclues an FCS, and we have
enough space in the trailer for the FCS, we assume we
have an FCS.
"Big enough" means 64 bytes or more; any frame that big
needs no trailer, as there's no need to pad an Ethernet
packet past 60 bytes.
The trailer must be at least 4 bytes long to have enough
space for an FCS. */
if (fcs_len == 4 || (tvb_reported_length(tvb) >= 64 &&
trailer_reported_length >= 4)) {
/* Either we know we have an FCS, or we believe we have an FCS. */
if (trailer_length < trailer_reported_length) {
/* The packet is claimed to have enough data for a 4-byte FCS,
but we didn't capture all of the packet.
Slice off the 4-byte FCS from the reported length, and
trim the captured length so it's no more than the reported
length; that will slice off what of the FCS, if any, is
in the captured packet. */
trailer_reported_length -= 4;
if (trailer_length > trailer_reported_length)
trailer_length = trailer_reported_length;
has_fcs = TRUE;
} else {
/* We captured all of the packet, including what appears to
be a 4-byte FCS. Slice it off. */
trailer_length -= 4;
trailer_reported_length -= 4;
has_fcs = TRUE;
}
}
}
if (trailer_length != 0) {
proto_tree_add_item(fh_tree, trailer_id, trailer_tvb, 0,
trailer_length, FALSE);
}
if (has_fcs) {
guint32 sent_fcs = tvb_get_ntohl(trailer_tvb, trailer_length);
guint32 fcs = crc32_tvb_802(tvb, tvb_length(tvb) - 4);
if (fcs == sent_fcs) {
proto_tree_add_text(fh_tree, trailer_tvb, trailer_length, 4,
"Frame check sequence: 0x%08x (correct)",
sent_fcs);
} else {
proto_tree_add_text(fh_tree, trailer_tvb, trailer_length, 4,
"Frame check sequence: 0x%08x (incorrect, should be 0x%08x)",
sent_fcs, fcs);
}
}
}
}
/* Called for the Ethernet Wiretap encapsulation type; pass the FCS length
reported to us. */
static void
dissect_eth_maybefcs(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
{
dissect_eth_common(tvb, pinfo, tree, pinfo->pseudo_header->eth.fcs_len);
}
/* Called by other dissectors - for now, we assume Ethernet encapsulated
inside other protocols doesn't include the FCS. */
static void
dissect_eth(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
{
dissect_eth_common(tvb, pinfo, tree, 0);
}
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", HFILL }},
{ &hf_eth_src,
{ "Source", "eth.src", FT_ETHER, BASE_NONE, NULL, 0x0,
"Source Hardware Address", HFILL }},
{ &hf_eth_len,
{ "Length", "eth.len", FT_UINT16, BASE_DEC, NULL, 0x0,
"", HFILL }},
/* registered here but handled in ethertype.c */
{ &hf_eth_type,
{ "Type", "eth.type", FT_UINT16, BASE_HEX, VALS(etype_vals), 0x0,
"", HFILL }},
{ &hf_eth_addr,
{ "Source or Destination Address", "eth.addr", FT_ETHER, BASE_NONE, NULL, 0x0,
"Source or Destination Hardware Address", HFILL }},
{ &hf_eth_trailer,
{ "Trailer", "eth.trailer", FT_BYTES, BASE_NONE, NULL, 0x0,
"Ethernet Trailer or Checksum", HFILL }},
};
static gint *ett[] = {
&ett_ieee8023,
&ett_ether2,
};
module_t *eth_module;
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));
/* subdissector code */
register_heur_dissector_list("eth", &heur_subdissector_list);
/* Register configuration preferences */
eth_module = prefs_register_protocol(proto_eth, NULL);
prefs_register_bool_preference(eth_module, "interpret_as_fw1_monitor",
"Interpret as FireWall-1 monitor file",
"Whether the capture file should be interpreted as a CheckPoint FireWall-1 monitor file",
&eth_interpret_as_fw1_monitor);
register_dissector("eth", dissect_eth, proto_eth);
eth_tap = register_tap("eth");
}
void
proto_reg_handoff_eth(void)
{
dissector_handle_t eth_handle, eth_maybefcs_handle;
/*
* Get a handle for the ISL dissector.
*/
isl_handle = find_dissector("isl");
fw1_handle = find_dissector("fw1");
eth_maybefcs_handle = create_dissector_handle(dissect_eth_maybefcs,
proto_eth);
dissector_add("wtap_encap", WTAP_ENCAP_ETHERNET, eth_maybefcs_handle);
eth_handle = find_dissector("eth");
dissector_add("ethertype", ETHERTYPE_ETHBRIDGE, eth_handle);
dissector_add("chdlctype", ETHERTYPE_ETHBRIDGE, eth_handle);
dissector_add("gre.proto", ETHERTYPE_ETHBRIDGE, eth_handle);
}
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