update dissector

dissector.lua

@@ -4,21 +4,27 @@ my_protocol = Proto("myprotocol", "My Custom Protocol")
 -- Define the fields you want to display in Wireshark
 my_protocol.fields = {}
 my_protocol.fields.type = ProtoField.string("myprotocol.type", "Type")
-my_protocol.fields.payload = ProtoField.bytes("myprotocol.payload", "Data")
+my_protocol.fields.payload = ProtoField.bytes("myprotocol.payload", "Payload")
 my_protocol.fields.len = ProtoField.uint16("myprotocol.len", "Len", base.HEX)
 
 my_protocol.fields.m_type 		= ProtoField.uint8("myprotocol.m_type", "Stream Type", base.HEX)
 my_protocol.fields.m_stream_id 	= ProtoField.uint8("myprotocol.m_stream_id", "Stream ID", base.HEX)
+my_protocol.fields.pkt_seq 		= ProtoField.uint16("myprotocol.pkt_seq", "Packet ID", base.HEX)
 my_protocol.fields.elem_count	= ProtoField.uint16("myprotocol.elem_count", "Elem count", base.DEC)
 
 my_protocol.fields.cmd_payload_len 	= ProtoField.uint16("myprotocol.cmd_payload_len", "CMD Payload Len", base.HEX)
 my_protocol.fields.cmd 				= ProtoField.uint16("myprotocol.cmd", "CMD", base.HEX)
 my_protocol.fields.start 			= ProtoField.uint16("myprotocol.start", "Start", base.HEX)
 my_protocol.fields.cmd_dest 		= ProtoField.uint16("myprotocol.cmd_dest", "Dest", base.HEX)
-my_protocol.fields.cmd_payload 		= ProtoField.bytes("myprotocol.payload", "Payload", base.DASH)
+my_protocol.fields.auth_token 		= ProtoField.bytes("myprotocol.auth_token", "CMD auth token", base.DASH)
+my_protocol.fields.cmd_payload 		= ProtoField.bytes("myprotocol.payload", "CMD Payload", base.DASH)
+-- jpeg | audio | continuation type?
+-- my_protocol.fields.cmd_payload 		= ProtoField.bytes("myprotocol.payload", "Payload", base.DASH)
+-- my_protocol.fields.cmd_payload 		= ProtoField.bytes("myprotocol.payload", "Payload", base.DASH)
 
 my_protocol.fields.encrypted 		= ProtoField.bool("myprotocol.encrypted", "Encrypted")
-my_protocol.fields.cmd_type 		= ProtoField.string("myprotocol.payload", "Cmd Pkt Type")
+my_protocol.fields.cmd_type 		= ProtoField.string("myprotocol.cmd_type", "Cmd Pkt Type")
+my_protocol.fields.decrypted_data	= ProtoField.bytes("myprotocol.decrypted_data", "Decrypted data")
 
 lut = {
     [0xf1f0] = "Close",
@@ -67,24 +73,60 @@ function my_protocol.dissector(buffer, pinfo, tree)
 
 	end
 	if packetname == "Drw" then
-		subtree:add(my_protocol.fields.len, buffer(2, 2))
+		local b_pkt_len = buffer(2, 2)
+		local pkt_len = b_pkt_len:uint()
+		subtree:add(my_protocol.fields.len, b_pkt_len)
 		subtree:add(my_protocol.fields.m_type, buffer(4, 1))
 		subtree:add(my_protocol.fields.m_stream_id, buffer(5, 1))
+		subtree:add(my_protocol.fields.pkt_seq, buffer(6, 2))
 		subtree:add_le(my_protocol.fields.start, buffer(8, 2))
 		subtree:add_le(my_protocol.fields.cmd, buffer(0xa, 2))
+		local b_payload_len = buffer(0xc, 2)
 		local payload_len = buffer(0xc, 2):le_uint()
-		subtree:add_le(my_protocol.fields.cmd_payload_len, buffer(0xc, 2))
 
-		subtree:add(my_protocol.fields.encrypted, payload_len >= 5):set_generated()
 		if buffer(0xb, 1):uint() % 2 == 1 then
 			cmdtype = "ack"
 		else
 			cmdtype = "cmd"
 		end
-		subtree:add(my_protocol.fields.cmd_type, cmdtype):set_generated()
 
+		subtree:add_le(my_protocol.fields.cmd_payload_len, b_payload_len)
 		subtree:add_le(my_protocol.fields.cmd_dest, buffer(0xe, 2))
-		subtree:add(my_protocol.fields.cmd_payload, buffer(0x10, payload_len))
+		-- inline value for short-payload bytes
+		subtree:add(my_protocol.fields.auth_token, buffer(0x10, 4))
+
+		subtree:add(my_protocol.fields.cmd_type, cmdtype):set_generated()
+		subtree:add(my_protocol.fields.encrypted, payload_len >= 5):set_generated()
+		if payload_len >= 5 then
+			local payload = buffer(0x14, payload_len - 4)
+			local dec_payload = ByteArray.new()
+			dec_payload:set_size(payload_len - 4)
+			for i=4,payload_len-5 do -- inclusive upper range
+				local v = buffer(0x14 + i-4, 1):uint()
+				if (v % 2) == 0 then
+					v = v + 1
+				else
+					v = v - 1
+				end
+				dec_payload:set_index(i, v)
+			end
+			for i=0,3 do
+				local v = buffer(pkt_len+i, 1):uint()
+				if v % 2 == 0 then
+					v = v + 1
+				else
+					v = v - 1
+				end
+				dec_payload:set_index(i, v)
+			end
+			local dec_tvb = ByteArray.tvb(dec_payload, "Decrypted payload")
+			subtree:add(my_protocol.fields.decrypted_data, dec_tvb:range(0, payload_len -4) ):set_generated()
+
+			local payload_tvb = ByteArray.tvb(buffer(0x14, payload_len -4):bytes(), "CMD Payload")
+			subtree:add(my_protocol.fields.cmd_payload, payload_tvb:range(0, payload_len -4))
+		end
+
+		--
 		-- subtree:add(my_protocol.fields.cmd, buffer(0xc, 2))
 
 	end