/* packet-eth.c * Routines for ethernet packet disassembly * * $Id: packet-eth.c,v 1.72 2002/01/21 07:36:34 guy Exp $ * * Ethereal - Network traffic analyzer * By Gerald Combs * 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 #endif #include #include #include "etypes.h" #include #include "packet-eth.h" #include "packet-ieee8023.h" #include "packet-ipx.h" #include "packet-isl.h" #include "packet-llc.h" /* 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; #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, 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]); /* 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, 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(pd, offset, len, 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(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree) { proto_item *ti; const guint8 *dst, *src; guint16 etype; volatile gboolean is_802_2; proto_tree *volatile fh_tree = NULL; if (check_col(pinfo->cinfo, COL_PROTOCOL)) col_set_str(pinfo->cinfo, 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) { /* 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; } /* 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); 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); } dissect_802_3(etype, is_802_2, tvb, ETH_HEADER_SIZE, pinfo, tree, fh_tree, hf_eth_len, hf_eth_trailer); } else { 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"); 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); } ethertype(etype, tvb, ETH_HEADER_SIZE, pinfo, tree, fh_tree, hf_eth_type, hf_eth_trailer); } } 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, }; 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, proto_eth); } void proto_reg_handoff_eth(void) { dissector_handle_t eth_handle; /* * Get a handle for the ISL dissector. */ isl_handle = find_dissector("isl"); eth_handle = find_dissector("eth"); dissector_add("wtap_encap", WTAP_ENCAP_ETHERNET, eth_handle); dissector_add("ethertype", ETHERTYPE_ETHBRIDGE, eth_handle); dissector_add("chdlctype", ETHERTYPE_ETHBRIDGE, eth_handle); dissector_add("gre.proto", ETHERTYPE_ETHBRIDGE, eth_handle); }