Add support for what appears to be 3Com's scheme for encapsulating XNS

over Token Ring (and presumably other link layers using 802.2 LLC), and
for the XNS IDP and SPP protocols.

svn path=/trunk/; revision=13577

1 files changed, 124 insertions, 0 deletions

diff --git a/epan/dissectors/packet-3com-xns.c b/epan/dissectors/packet-3com-xns.c
new file mode 100644
index 0000000000..c604c55f85
--- /dev/null
+++ b/epan/dissectors/packet-3com-xns.c
@@ -0,0 +1,124 @@
+/* packet-xns-llc.c
+ * Routines for 3Com's encapsulation of XNS over 802.2 LLC
+ * (and other protocols using DSAP 80)
+ *
+ * $Id$
+ *
+ * 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 <glib.h>
+#include <epan/packet.h>
+#include "etypes.h"
+
+static int proto_3com_xns = -1;
+
+static int hf_3com_xns_type_ethertype = -1;
+static int hf_3com_xns_type_retix_bpdu = -1;
+
+static gint ett_3com_xns = -1;
+
+static const value_string retix_bpdu_type_vals[] = {
+	{ 0x0004, "Retix Spanning Tree" },
+	{ 0, NULL }
+};
+
+static dissector_handle_t retix_bpdu_handle;
+
+/*
+ * Apparently 3Com had some scheme for encapsulating XNS in 802.2 LLC,
+ * using a DSAP and SSAP of 0x80, and putting a 2-byte field that appeared
+ * to contain, at least for IPP, the Ethertype value for IPP.
+ *
+ * We assume that the value there is an Ethertype value, except for
+ * the Retix spanning tree protocol, which also uses a DSAP and SSAP
+ * of 0x80 but has, at least in one capture, 0x0004 as the type
+ * field.  We handle that specially.
+ *
+ * XXX - I've also seen packets on 802.11 with a DSAP and SSAP of 0x80,
+ * but with random stuff that appears neither to be XNS nor Retix
+ * spanning tree.
+ */
+static void
+dissect_3com_xns(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
+{
+	proto_tree *subtree = NULL;
+	proto_tree *ti;
+	guint16 type;
+
+	if (check_col(pinfo->cinfo, COL_PROTOCOL))
+		col_set_str(pinfo->cinfo, COL_PROTOCOL, "3Com XNS");
+	if (check_col(pinfo->cinfo, COL_INFO))
+		col_clear(pinfo->cinfo, COL_INFO);
+
+	if (tree) {
+		ti = proto_tree_add_item(tree, proto_3com_xns, tvb, 0, 4, FALSE);
+		subtree = proto_item_add_subtree(ti, ett_3com_xns);
+	}
+
+	type = tvb_get_ntohs(tvb, 0);
+	if (type == 0x0004) {
+		proto_tree_add_uint(subtree, hf_3com_xns_type_retix_bpdu,
+		    tvb, 0, 2, type);
+		call_dissector(retix_bpdu_handle,
+		    tvb_new_subset(tvb, 2, -1, -1), pinfo, tree);
+	} else {
+		ethertype(type, tvb, 2, pinfo, tree, subtree,
+		    hf_3com_xns_type_ethertype, -1, 0);
+	}
+}
+
+void
+proto_register_3com_xns(void)
+{
+	static hf_register_info hf[] = {
+		/* registered here but handled in ethertype.c */
+		{ &hf_3com_xns_type_ethertype,
+		{ "Type", "xnsllc.type", FT_UINT16, BASE_HEX,
+			VALS(etype_vals), 0x0, "", HFILL }},
+
+		{ &hf_3com_xns_type_retix_bpdu,
+		{ "Type", "xnsllc.type", FT_UINT16, BASE_HEX,
+			VALS(retix_bpdu_type_vals), 0x0, "", HFILL }},
+	};
+
+	static gint *ett[] ={
+		&ett_3com_xns,
+	};
+
+	proto_3com_xns = proto_register_protocol("3Com XNS Encapsulation", "3COMXNS", "3comxns");
+	proto_register_field_array(proto_3com_xns, hf, array_length(hf)); 
+	proto_register_subtree_array(ett, array_length(ett));
+}
+
+void
+proto_reg_handoff_3com_xns(void)
+{
+	dissector_handle_t our_xns_handle;
+
+	retix_bpdu_handle = find_dissector("rbpdu");
+
+	our_xns_handle = create_dissector_handle(dissect_3com_xns,
+	    proto_3com_xns);
+	dissector_add("llc.dsap", 0x80, our_xns_handle);
+}