/* packet-eth.c * Routines for ethernet packet disassembly * * $Id: packet-eth.c,v 1.44 2000/08/13 14:08:10 deniel 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 "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; #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 not 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 dissect_llc(). -- 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; /* These are static because gcc says that they might get clobbered * otherwise. */ static tvbuff_t *next_tvb = NULL; static tvbuff_t *trailer_tvb; static proto_tree *fh_tree; CHECK_DISPLAY_AS_DATA(proto_eth, tvb, pinfo, tree); tvb_compat(tvb, &pd, (int*)ð_offset); /* Reset this static variable to NULL since I test it's value later */ trailer_tvb = NULL; pinfo->current_proto = "Ethernet"; orig_captured_len = pinfo->captured_len; if (check_col(pinfo->fd, COL_PROTOCOL)) col_add_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 ) { dissect_isl(pd, eth_offset, pinfo->fd, 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. */ length += eth_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; if (check_col(pinfo->fd, COL_INFO)) col_add_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; /* Give the next dissector only 'length' number of bytes */ if (etype <= IEEE_802_3_MAX_LEN) { 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) { next_tvb = tvb_new_subset(tvb, ETH_HEADER_SIZE, -1, etype); } ENDTRY; } else { next_tvb = tvb_new_subset(tvb, ETH_HEADER_SIZE, -1, -1); } switch (ethhdr_type) { case ETHERNET_802_3: dissect_ipx(next_tvb, pinfo, tree); break; case ETHERNET_802_2: dissect_llc(next_tvb, pinfo, tree); break; case ETHERNET_II: ethertype(etype, tvb, ETH_HEADER_SIZE, pinfo, tree, fh_tree, hf_eth_type); break; } /* If there's some bytes left over, mark them. */ if (trailer_tvb && tree) { int trailer_length; const guint8 *ptr; trailer_length = tvb_length(trailer_tvb); if (trailer_length > 0) { ptr = tvb_get_ptr(trailer_tvb, 0, trailer_length); proto_tree_add_bytes(fh_tree, hf_eth_trailer, tvb, ETH_HEADER_SIZE + etype, trailer_length, ptr); } } } 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", "eth" ); proto_register_field_array(proto_eth, hf, array_length(hf)); proto_register_subtree_array(ett, array_length(ett)); }