GPRS: Add something that should have become a histogram display...

One small problem... there is no way to be called at the end of
reading a pcap file...

openbsc/contrib/gprs/gprs-bssgp-histogram.lua

@@ -0,0 +1,62 @@
+-- Simple LUA script to print the size of BSSGP messages over their type...
+
+do
+	local ip_bucket = {}
+
+	local function init_listener()
+		-- handle the port as NS over IP
+		local udp_port_table = DissectorTable.get("udp.port")
+		local gprs_ns_dis = Dissector.get("gprs_ns")
+		udp_port_table:add(23000,gprs_ns_dis)
+
+		-- bssgp filters
+		local bssgp_pdu_get = Field.new("bssgp.pdu_type")
+		local udp_length_get = Field.new("udp.length")
+
+		local tap = Listener.new("ip", "udp.port == 23000")
+		function tap.packet(pinfo,tvb,ip)
+			local pdu = bssgp_pdu_get()
+			local len = udp_length_get()
+
+			-- only handle bssgp, but we also want the IP frame
+			if not pdu then
+				return
+			end
+
+			pdu = tostring(pdu)
+			if tonumber(pdu) == 0 or tonumber(pdu) == 1 then
+				return
+			end
+
+			local ip_src = tostring(ip.ip_src)
+			local bssgp_histo = ip_bucket[ip_src]
+			if not bssgp_histo then
+				bssgp_histo = {}
+				ip_bucket[ip_src] = bssgp_histo
+			end
+
+			local key = pdu
+			local bucket = bssgp_histo[key]
+			if not bucket then
+				bucket = {}
+				bssgp_histo[key] = bucket
+			end
+
+			table.insert(bucket, tostring(len))
+			print("IP: " .. ip_src .. " PDU: " .. pdu .. " Length: " .. tostring(len))
+		end
+
+		function tap.draw()
+			-- well... this will not be called...
+--			for ip,bssgp_histo in pairs(dumpers) do
+--				print("IP " .. ip)
+--			end
+		end
+
+		function tap.reset()
+			-- well... this will not be called...
+		end
+	end
+
+	init_listener()
+end