Discard the WTAP_ENCAP_LAPD encapsulation type in favor of a

WTAP_ENCAP_ISDN encapsulation type, which includes a pseudo-header
giving the direction (user-to-network or network-to-user) and the
channel number.

Add a new circuit type, using the ISDN channel number as the circuit ID.

Add an ISDN dissector to put the direction and channel number into the
protocol tree and to call the appropriate dissector for the payload
based on the channel (LAPD for the D channel; V.120, PPP, or data for B
channels, based on some heuristics).


git-svn-id: http://anonsvn.wireshark.org/wireshark/trunk@6521 f5534014-38df-0310-8fa8-9805f1628bb7

1 files changed, 229 insertions, 0 deletions

diff --git a/packet-isdn.c b/packet-isdn.c
new file mode 100644
index 0000000000..ad9ca1d270
--- /dev/null
+++ b/packet-isdn.c
@@ -0,0 +1,229 @@
+/* packet-isdn.c
+ * Routines for ISDN packet disassembly
+ *
+ * $Id: packet-isdn.c,v 1.1 2002/10/31 07:12:23 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 <stdio.h>
+#include <glib.h>
+#include <epan/packet.h>
+#include <epan/circuit.h>
+
+static int proto_isdn = -1;
+static int hf_isdn_direction = -1;
+static int hf_isdn_channel = -1;
+
+static gint ett_isdn = -1;
+
+static dissector_handle_t lapd_handle;
+static dissector_handle_t ppp_hdlc_handle;
+static dissector_handle_t v120_handle;
+static dissector_handle_t data_handle;
+
+static const true_false_string direction_tfs = {
+	"User-to-network",
+	"Network-to-user"
+};
+
+static const value_string channel_vals[] = {
+	{ 0,	"D" },
+	{ 1,	"B1" },
+	{ 2,	"B2" },
+	{ 3,	"B3" },
+	{ 4,	"B4" },
+	{ 5,	"B5" },
+	{ 6,	"B6" },
+	{ 7,	"B7" },
+	{ 8,	"B8" },
+	{ 9,	"B9" },
+	{ 10,	"B10" },
+	{ 11,	"B11" },
+	{ 12,	"B12" },
+	{ 13,	"B13" },
+	{ 14,	"B14" },
+	{ 15,	"B15" },
+	{ 16,	"B16" },
+	{ 17,	"B17" },
+	{ 18,	"B19" },
+	{ 19,	"B19" },
+	{ 20,	"B20" },
+	{ 21,	"B21" },
+	{ 22,	"B22" },
+	{ 23,	"B23" },
+	{ 24,	"B24" },
+	{ 25,	"B25" },
+	{ 26,	"B26" },
+	{ 27,	"B27" },
+	{ 28,	"B29" },
+	{ 29,	"B29" },
+	{ 30,	"B30" },
+	{ 0,	NULL }
+};
+
+static void
+dissect_isdn(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
+{
+	proto_tree *isdn_tree;
+	proto_item *ti;
+	static const char v120_sabme[3] = { 0x08, 0x01, 0x7F };
+	static const char ppp[2] = { 0xFF, 0x03 };
+	circuit_t *circuit;
+
+	if (check_col(pinfo->cinfo, COL_PROTOCOL))
+		col_set_str(pinfo->cinfo, COL_PROTOCOL, "ISDN");
+
+	if (pinfo->pseudo_header->isdn.uton) {
+		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 {
+		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");
+	}
+
+	pinfo->ctype = CT_ISDN;
+	pinfo->circuit_id = pinfo->pseudo_header->isdn.channel;
+
+	if (tree) {
+		ti = proto_tree_add_item(tree, proto_isdn, tvb, 0, 0, FALSE);
+		isdn_tree = proto_item_add_subtree(ti, ett_isdn);
+
+		proto_tree_add_boolean(isdn_tree, hf_isdn_direction, tvb, 0, 0,
+		    pinfo->pseudo_header->isdn.uton);
+		proto_tree_add_uint(isdn_tree, hf_isdn_channel, tvb, 0, 0,
+		    pinfo->pseudo_header->isdn.channel);
+	}
+
+	/*
+	 * Set up a circuit for this channel, and assign it a dissector.
+	 */
+	circuit = find_circuit(pinfo->ctype, pinfo->circuit_id);
+	if (circuit == NULL)
+		circuit = circuit_new(pinfo->ctype, pinfo->circuit_id);
+
+	if (circuit_get_dissector(circuit) == NULL) {
+		/*
+		 * We don't yet know the type of traffic on the circuit.
+		 */
+		switch (pinfo->pseudo_header->isdn.channel) {
+
+		case 0:
+			/*
+			 * D-channel.  Treat it as LAPD.
+			 */
+			circuit_set_dissector(circuit, lapd_handle);
+			break;
+
+		default:
+			/*
+			 * B-channel.
+			 *
+			 * We don't know yet whether the datastream is
+			 * V.120 or not; this heuristic tries to figure
+			 * that out.
+			 *
+			 * We cannot glean this from the Q.931 SETUP message,
+			 * because no commercial V.120 implementation I've
+			 * seen actually sets the V.120 protocol discriminator
+			 * (that, or I'm misreading the spec badly).
+			 *
+			 * TODO: close the circuit after a close on the B
+			 * channel is detected.
+			 *
+			 *	-Bert Driehuis (from the i4btrace reader;
+			 *	 this heuristic was moved from there to
+			 *	 here)
+			 *
+			 * XXX - I don't know that one can guarantee that
+			 * the SABME will appear in the first frame on
+			 * the channels, so we probably can't just say
+			 * "it must be PPP" if we don't immediately see
+			 * the V.120 SABME frame, so we do so only if
+			 * we see the 0xFF 0x03.  Unfortunately, that
+			 * won't do the right thing if the PPP-over-HDLC
+			 * headers aren't being used....
+			 */
+			if (tvb_bytes_exist(tvb, 0, 3) &&
+			    tvb_memeql(tvb, 0, v120_sabme, 3) == 0) {
+				/*
+				 * We assume this is V.120.
+				 */
+				circuit_set_dissector(circuit, v120_handle);
+			} else if (tvb_bytes_exist(tvb, 0, 2) &&
+			    tvb_memeql(tvb, 0, ppp, 2) == 0) {
+				/*
+				 * We assume this is PPP.
+				 */
+				circuit_set_dissector(circuit, ppp_hdlc_handle);
+			}
+			break;
+		}
+	}
+
+	if (!try_circuit_dissector(pinfo->ctype, pinfo->circuit_id,
+	    tvb, pinfo, tree))
+		call_dissector(data_handle, tvb, pinfo, tree);
+}
+
+void
+proto_register_isdn(void)
+{
+	static hf_register_info hf[] = {
+		{ &hf_isdn_direction,
+		{ "Direction",	"isdn.direction", FT_BOOLEAN, BASE_NONE,
+		  TFS(&direction_tfs), 0x0, "", HFILL }},
+
+		{ &hf_isdn_channel,
+		{ "Channel",	"isdn.channel", FT_UINT8, BASE_DEC,
+		  VALS(channel_vals), 0x0, "", HFILL }},
+	};
+	static gint *ett[] = {
+		&ett_isdn,
+	};
+	proto_isdn = proto_register_protocol("ISDN", "ISDN", "isdn");
+	proto_register_field_array(proto_isdn, hf, array_length(hf));
+	proto_register_subtree_array(ett, array_length(ett));
+}
+
+void
+proto_reg_handoff_isdn(void)
+{
+	dissector_handle_t isdn_handle;
+
+	/*
+	 * Get handles for the LAPD, PPP, and V.120 dissectors.
+	 */
+	lapd_handle = find_dissector("lapd");
+	ppp_hdlc_handle = find_dissector("ppp_hdlc");
+	v120_handle = find_dissector("v120");
+	data_handle = find_dissector("data");
+
+	isdn_handle = create_dissector_handle(dissect_isdn, proto_isdn);
+
+	dissector_add("wtap_encap", WTAP_ENCAP_ISDN, isdn_handle);
+}