1 files changed, 296 insertions, 0 deletions
diff --git a/epan/dissectors/packet-lapd.c b/epan/dissectors/packet-lapd.c
new file mode 100644
index 0000000000..d766047ef8
--- /dev/null
+++ b/epan/dissectors/packet-lapd.c
@@ -0,0 +1,296 @@
+/* packet-lapd.c
+ * Routines for LAPD frame disassembly
+ * Gilbert Ramirez <gram@alumni.rice.edu>
+ *
+ * $Id$
+ *
+ * Ethereal - Network traffic analyzer
+ * By Gerald Combs <gerald@ethereal.com>
+ * 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
+
+#include <stdio.h>
+#include <glib.h>
+#include <string.h>
+#include <epan/packet.h>
+#include "xdlc.h"
+
+#include "lapd_sapi.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 int hf_lapd_n_r = -1;
+static int hf_lapd_n_s = -1;
+static int hf_lapd_p = -1;
+static int hf_lapd_p_ext = -1;
+static int hf_lapd_f = -1;
+static int hf_lapd_f_ext = -1;
+static int hf_lapd_s_ftype = -1;
+static int hf_lapd_u_modifier_cmd = -1;
+static int hf_lapd_u_modifier_resp = -1;
+static int hf_lapd_ftype_i = -1;
+static int hf_lapd_ftype_s_u = -1;
+static int hf_lapd_ftype_s_u_ext = -1;
+
+static gint ett_lapd = -1;
+static gint ett_lapd_address = -1;
+static gint ett_lapd_control = -1;
+
+static dissector_table_t lapd_sapi_dissector_table;
+
+static dissector_handle_t data_handle;
+static dissector_handle_t tei_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 */
+
+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 }
+};
+
+/* Used only for U frames */
+static const xdlc_cf_items lapd_cf_items = {
+	NULL,
+	NULL,
+	&hf_lapd_p,
+	&hf_lapd_f,
+	NULL,
+	&hf_lapd_u_modifier_cmd,
+	&hf_lapd_u_modifier_resp,
+	NULL,
+	&hf_lapd_ftype_s_u
+};
+
+/* Used only for I and S frames */
+static const xdlc_cf_items lapd_cf_items_ext = {
+	&hf_lapd_n_r,
+	&hf_lapd_n_s,
+	&hf_lapd_p_ext,
+	&hf_lapd_f_ext,
+	&hf_lapd_s_ftype,
+	NULL,
+	NULL,
+	&hf_lapd_ftype_i,
+	&hf_lapd_ftype_s_u_ext
+};
+
+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->p2p_dir == P2P_DIR_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 {
+		/* XXX - what if the direction is unknown? */
+		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, &lapd_cf_items, &lapd_cf_items_ext, NULL, NULL,
+	    is_response, TRUE, FALSE);
+	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 */
+		if (!dissector_try_port(lapd_sapi_dissector_table, sapi,
+		    next_tvb, pinfo, tree))
+			call_dissector(data_handle,next_tvb, pinfo, tree);
+	} 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 }},
+
+	{ &hf_lapd_n_r,
+	    { "N(R)", "lapd.control.n_r", FT_UINT16, BASE_DEC,
+		NULL, XDLC_N_R_EXT_MASK, "", HFILL }},
+
+	{ &hf_lapd_n_s,
+	    { "N(S)", "lapd.control.n_s", FT_UINT16, BASE_DEC,
+		NULL, XDLC_N_S_EXT_MASK, "", HFILL }},
+
+	{ &hf_lapd_p,
+	    { "Poll", "lapd.control.p", FT_BOOLEAN, 8,
+		TFS(&flags_set_truth), XDLC_P_F, "", HFILL }},
+
+	{ &hf_lapd_p_ext,
+	    { "Poll", "lapd.control.p", FT_BOOLEAN, 16,
+		TFS(&flags_set_truth), XDLC_P_F_EXT, "", HFILL }},
+
+	{ &hf_lapd_f,
+	    { "Final", "lapd.control.f", FT_BOOLEAN, 8,
+		TFS(&flags_set_truth), XDLC_P_F, "", HFILL }},
+
+	{ &hf_lapd_f_ext,
+	    { "Final", "lapd.control.f", FT_BOOLEAN, 16,
+		TFS(&flags_set_truth), XDLC_P_F_EXT, "", HFILL }},
+
+	{ &hf_lapd_s_ftype,
+	    { "Supervisory frame type", "lapd.control.s_ftype", FT_UINT16, BASE_HEX,
+		VALS(stype_vals), XDLC_S_FTYPE_MASK, "", HFILL }},
+
+	{ &hf_lapd_u_modifier_cmd,
+	    { "Command", "lapd.control.u_modifier_cmd", FT_UINT8, BASE_HEX,
+		VALS(modifier_vals_cmd), XDLC_U_MODIFIER_MASK, "", HFILL }},
+
+	{ &hf_lapd_u_modifier_resp,
+	    { "Response", "lapd.control.u_modifier_resp", FT_UINT8, BASE_HEX,
+		VALS(modifier_vals_resp), XDLC_U_MODIFIER_MASK, "", HFILL }},
+
+	{ &hf_lapd_ftype_i,
+	    { "Frame type", "lapd.control.ftype", FT_UINT16, BASE_HEX,
+		VALS(ftype_vals), XDLC_I_MASK, "", HFILL }},
+
+	{ &hf_lapd_ftype_s_u,
+	    { "Frame type", "lapd.control.ftype", FT_UINT8, BASE_HEX,
+		VALS(ftype_vals), XDLC_S_U_MASK, "", HFILL }},
+
+	{ &hf_lapd_ftype_s_u_ext,
+	    { "Frame type", "lapd.control.ftype", FT_UINT16, BASE_HEX,
+		VALS(ftype_vals), XDLC_S_U_MASK, "", 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));
+
+    register_dissector("lapd", dissect_lapd, proto_lapd);
+
+    lapd_sapi_dissector_table = register_dissector_table("lapd.sapi",
+	    "LAPD SAPI", FT_UINT16, BASE_DEC);
+}
+
+void
+proto_reg_handoff_lapd(void)
+{
+	data_handle = find_dissector("data");
+	tei_handle = find_dissector("tei");
+}