Fix for bug 1545.

Add a preference to support BVLC on non standard UDP port.

svn path=/trunk/; revision=21747

1 files changed, 38 insertions, 16 deletions

diff --git a/epan/dissectors/packet-bvlc.c b/epan/dissectors/packet-bvlc.c
index 19d5fb8fb2..b4caf9052e 100644
--- a/epan/dissectors/packet-bvlc.c
+++ b/epan/dissectors/packet-bvlc.c
@@ -39,6 +39,17 @@
 
 #include <epan/packet.h>
 
+/* Taken from add-135a (BACnet-IP-standard paper):
+ *
+ * The default UDP port for both directed messages and broadcasts shall
+ * be X'BAC0' and all B/IP devices shall support it. In some cases,
+ * e.g., a situation where it is desirable for two groups of BACnet devices
+ * to coexist independently on the same IP subnet, the UDP port may be
+ * configured locally to a different value without it being considered
+ * a violation of this protocol.
+ */
+static int additional_bvlc_udp_port = 0;
+
 static int proto_bvlc = -1;
 static int hf_bvlc_type = -1;
 static int hf_bvlc_function = -1;
@@ -306,6 +317,8 @@ dissect_bvlc(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
 	return tvb_length(tvb);
 }
 
+void proto_reg_handoff_bvlc(void);
+
 void
 proto_register_bvlc(void)
 {
@@ -390,12 +403,20 @@ proto_register_bvlc(void)
 		&ett_fdt,
 	};
 
+	module_t *bvlc_module;
+
 	proto_bvlc = proto_register_protocol("BACnet Virtual Link Control",
 	    "BVLC", "bvlc");
 
 	proto_register_field_array(proto_bvlc, hf, array_length(hf));
 	proto_register_subtree_array(ett, array_length(ett));
 
+	bvlc_module = prefs_register_protocol(proto_bvlc, proto_reg_handoff_bvlc);
+	prefs_register_uint_preference(bvlc_module, "additional_udp_port",
+					"Additional UDP port", "Set an additional UDP port, "
+					"besides the standard X'BAC0' (47808) port.",
+					10, &additional_bvlc_udp_port);
+
 	new_register_dissector("bvlc", dissect_bvlc, proto_bvlc);
 
 	bvlc_dissector_table = register_dissector_table("bvlc.function",
@@ -405,22 +426,23 @@ proto_register_bvlc(void)
 void
 proto_reg_handoff_bvlc(void)
 {
-	dissector_handle_t bvlc_handle;
+	static int bvlc_initialized = FALSE;
+	static dissector_handle_t bvlc_handle;
+	static int bvlc_udp_port;
+	
+	if (!bvlc_initialized)
+	{
+		bvlc_handle = find_dissector("bvlc");
+		dissector_add("udp.port", 0xBAC0, bvlc_handle);
+		bvlc_initialized = TRUE;
+	}
+	else
+	{
+		dissector_delete("udp.port", bvlc_udp_port, bvlc_handle);
+	}
+
+	bvlc_udp_port = additional_bvlc_udp_port;
+	dissector_add("udp.port", bvlc_udp_port, bvlc_handle);
 
-	bvlc_handle = find_dissector("bvlc");
-	dissector_add("udp.port", 0xBAC0, bvlc_handle);
 	data_handle = find_dissector("data");
 }
-/* Taken from add-135a (BACnet-IP-standard paper):
- *
- * The default UDP port for both directed messages and broadcasts shall
- * be X'BAC0' and all B/IP devices shall support it. In some cases,
- * e.g., a situation where it is desirable for two groups of BACnet devices
- * to coexist independently on the same IP subnet, the UDP port may be
- * configured locally to a different value without it being considered
- * a violation of this protocol.
- *
- * This dissector does not analyse UDP packets other than on port 0xBAC0.
- * If you changed your BACnet port locally, use the wireshark feature
- * "Decode As".
- */