Major revisions to Modbus analyzer support (not quite done yet).

- Renamed many data structures to align with most recent standard.

- Reworked modbus events to make them more canonically "Bro".

- Converted the Modbus analyzer to a simpler style for easier maintenance.

- Modbus coil related events still don't work (I haven't finished the
  function for converting the data structures).

- Modbus file record events remain incomplete.

scripts/base/protocols/modbus/main.bro

@@ -1,12 +1,26 @@
-##! Base Modbus analysis script. For now it does not do anything else than
-##! activating the analyzer for connections on Modbus port 502/tcp.  
+##! Base Modbus analysis script.
 
 module Modbus;
 
 export {
+
 }
 
 # Configure DPD and the packet filter.
 redef capture_filters += { ["modbus"] = "tcp port 502" };
 redef dpd_config += { [ANALYZER_MODBUS] = [$ports = set(502/tcp)] };
 redef likely_server_ports += { 502/tcp };
+
+
+event modbus_exception(c: connection, header: ModbusHeaders, code: count)
+	{
+	print fmt("%.6f %s There was an exception: %s", network_time(), c$id, exception_codes[code]);
+	}
+
+event modbus_message(c: connection, header: ModbusHeaders, is_orig: bool)
+	{
+	#if ( function_codes[header$function_code] in set("READ_MULTIPLE_REGISTERS", "READ_WRITE_REGISTERS", "WRITE_MULTIPLE_REGISTERS") )
+	#	return; 
+
+	print fmt("%.6f %s %s: %s", network_time(), c$id, is_orig ? "request":"response", function_codes[header$function_code]);
+	}