/* packet-lapd.c * Routines for LAPD frame disassembly * Gilbert Ramirez * * $Id: packet-lapd.c,v 1.29 2002/02/22 08:54:54 guy Exp $ * * Ethereal - Network traffic analyzer * By Gerald Combs * Copyright 1998 * * 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 #include #include "xdlc.h" /* ISDN/LAPD references: * * http://www.cisco.com/univercd/cc/td/doc/cisintwk/ito_doc/isdn.htm * http://www.ece.wpi.edu/courses/ee535/hwk11cd95/agrebe/agrebe.html * http://www.acacia-net.com/Clarinet/Protocol/q9213o84.htm */ static int proto_lapd = -1; static int hf_lapd_address = -1; static int hf_lapd_sapi = -1; static int hf_lapd_cr = -1; static int hf_lapd_ea1 = -1; static int hf_lapd_tei = -1; static int hf_lapd_ea2 = -1; static int hf_lapd_control = -1; static gint ett_lapd = -1; static gint ett_lapd_address = -1; static gint ett_lapd_control = -1; static dissector_handle_t q931_handle; static dissector_handle_t data_handle; /* * Bits in the address field. */ #define LAPD_SAPI 0xfc00 /* Service Access Point Identifier */ #define LAPD_SAPI_SHIFT 10 #define LAPD_CR 0x0200 /* Command/Response bit */ #define LAPD_EA1 0x0100 /* First Address Extension bit */ #define LAPD_TEI 0x00fe /* Terminal Endpoint Identifier */ #define LAPD_EA2 0x0001 /* Second Address Extension bit */ #define LAPD_SAPI_Q931 0 /* Q.931 call control procedure */ #define LAPD_SAPI_PM_Q931 1 /* Packet mode Q.931 call control procedure */ #define LAPD_SAPI_X25 16 /* X.25 Level 3 procedures */ #define LAPD_SAPI_L2 63 /* Layer 2 management procedures */ static const value_string lapd_sapi_vals[] = { { LAPD_SAPI_Q931, "Q.931 Call control procedure" }, { LAPD_SAPI_PM_Q931, "Packet mode Q.931 Call control procedure" }, { LAPD_SAPI_X25, "X.25 Level 3 procedures" }, { LAPD_SAPI_L2, "Layer 2 management procedures" }, { 0, NULL } }; static void dissect_lapd(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree) { proto_tree *lapd_tree, *addr_tree; proto_item *lapd_ti, *addr_ti; guint16 control; int lapd_header_len; guint16 address, cr, sapi; gboolean is_response; tvbuff_t *next_tvb; if (check_col(pinfo->cinfo, COL_PROTOCOL)) col_set_str(pinfo->cinfo, COL_PROTOCOL, "LAPD"); if (check_col(pinfo->cinfo, COL_INFO)) col_clear(pinfo->cinfo, COL_INFO); address = tvb_get_ntohs(tvb, 0); cr = address & LAPD_CR; sapi = (address & LAPD_SAPI) >> LAPD_SAPI_SHIFT; lapd_header_len = 2; /* address */ if (pinfo->pseudo_header->p2p.sent) { is_response = cr ? TRUE : FALSE; if(check_col(pinfo->cinfo, COL_RES_DL_DST)) col_set_str(pinfo->cinfo, COL_RES_DL_DST, "Network"); if(check_col(pinfo->cinfo, COL_RES_DL_SRC)) col_set_str(pinfo->cinfo, COL_RES_DL_SRC, "User"); } else { is_response = cr ? FALSE : TRUE; if(check_col(pinfo->cinfo, COL_RES_DL_DST)) col_set_str(pinfo->cinfo, COL_RES_DL_DST, "User"); if(check_col(pinfo->cinfo, COL_RES_DL_SRC)) col_set_str(pinfo->cinfo, COL_RES_DL_SRC, "Network"); } if (tree) { lapd_ti = proto_tree_add_item(tree, proto_lapd, tvb, 0, -1, FALSE); lapd_tree = proto_item_add_subtree(lapd_ti, ett_lapd); addr_ti = proto_tree_add_uint(lapd_tree, hf_lapd_address, tvb, 0, 2, address); addr_tree = proto_item_add_subtree(addr_ti, ett_lapd_address); proto_tree_add_uint(addr_tree, hf_lapd_sapi,tvb, 0, 1, address); proto_tree_add_uint(addr_tree, hf_lapd_cr, tvb, 0, 1, address); proto_tree_add_uint(addr_tree, hf_lapd_ea1, tvb, 0, 1, address); proto_tree_add_uint(addr_tree, hf_lapd_tei, tvb, 1, 1, address); proto_tree_add_uint(addr_tree, hf_lapd_ea2, tvb, 1, 1, address); } else { lapd_ti = NULL; lapd_tree = NULL; } control = dissect_xdlc_control(tvb, 2, pinfo, lapd_tree, hf_lapd_control, ett_lapd_control, is_response, TRUE); lapd_header_len += XDLC_CONTROL_LEN(control, TRUE); if (tree) proto_item_set_len(lapd_ti, lapd_header_len); next_tvb = tvb_new_subset(tvb, lapd_header_len, -1, -1); if (XDLC_IS_INFORMATION(control)) { /* call next protocol */ switch (sapi) { case LAPD_SAPI_Q931: call_dissector(q931_handle, next_tvb, pinfo, tree); break; default: call_dissector(data_handle,next_tvb, pinfo, tree); break; } } else call_dissector(data_handle,next_tvb, pinfo, tree); } void proto_register_lapd(void) { static hf_register_info hf[] = { { &hf_lapd_address, { "Address Field", "lapd.address", FT_UINT16, BASE_HEX, NULL, 0x0, "Address", HFILL }}, { &hf_lapd_sapi, { "SAPI", "lapd.sapi", FT_UINT16, BASE_DEC, VALS(lapd_sapi_vals), LAPD_SAPI, "Service Access Point Identifier", HFILL }}, { &hf_lapd_cr, { "C/R", "lapd.cr", FT_UINT16, BASE_DEC, NULL, LAPD_CR, "Command/Response bit", HFILL }}, { &hf_lapd_ea1, { "EA1", "lapd.ea1", FT_UINT16, BASE_DEC, NULL, LAPD_EA1, "First Address Extension bit", HFILL }}, { &hf_lapd_tei, { "TEI", "lapd.tei", FT_UINT16, BASE_DEC, NULL, LAPD_TEI, "Terminal Endpoint Identifier", HFILL }}, { &hf_lapd_ea2, { "EA2", "lapd.ea2", FT_UINT16, BASE_DEC, NULL, LAPD_EA2, "Second Address Extension bit", HFILL }}, { &hf_lapd_control, { "Control Field", "lapd.control", FT_UINT16, BASE_HEX, NULL, 0x0, "Control field", HFILL }}, }; static gint *ett[] = { &ett_lapd, &ett_lapd_address, &ett_lapd_control, }; proto_lapd = proto_register_protocol("Link Access Procedure, Channel D (LAPD)", "LAPD", "lapd"); proto_register_field_array (proto_lapd, hf, array_length(hf)); proto_register_subtree_array(ett, array_length(ett)); } void proto_reg_handoff_lapd(void) { dissector_handle_t lapd_handle; /* * Get handle for the Q.931 dissector. */ q931_handle = find_dissector("q931"); data_handle = find_dissector("data"); lapd_handle = create_dissector_handle(dissect_lapd, proto_lapd); dissector_add("wtap_encap", WTAP_ENCAP_LAPD, lapd_handle); }