initial commit

client/init.lua

@@ -0,0 +1,142 @@
+local socket = require("socket")
+
+local network = {}
+
+local client
+
+-- Packet IDs
+network.MSG_KEY_PRESS = 1
+network.MSG_GAMESTATE = 2
+
+--------------------------------------------------
+-- Packing
+--------------------------------------------------
+
+local function packU16(n)
+	return string.char(math.floor(n / 256) % 256, n % 256)
+end
+
+local function packU32(n)
+	return string.char(math.floor(n / 16777216) % 256, math.floor(n / 65536) % 256, math.floor(n / 256) % 256, n % 256)
+end
+
+local function unpackU16(s)
+	local b1, b2 = s:byte(1, 2)
+	return b1 * 256 + b2
+end
+
+local function unpackU32(s)
+	local b1, b2, b3, b4 = s:byte(1, 4)
+
+	return b1 * 16777216 + b2 * 65536 + b3 * 256 + b4
+end
+
+--------------------------------------------------
+-- Connection
+--------------------------------------------------
+
+function network.connect(ip, port)
+	client = assert(socket.tcp())
+
+	client:settimeout(0)
+
+	local ok, err = client:connect(ip, port)
+
+	-- Non-blocking connect is expected
+	if not ok and err ~= "timeout" then
+		error(err)
+	end
+
+	print("Connecting...")
+end
+
+--------------------------------------------------
+-- Sending
+--------------------------------------------------
+
+function network.sendPacket(id, payload)
+	if not client then
+		return
+	end
+
+	payload = payload or ""
+
+	local length = 2 + #payload
+
+	local packet = packU32(length) .. packU16(id) .. payload
+
+	client:send(packet)
+end
+
+function network.sendKey(key)
+	network.sendPacket(network.MSG_KEY_PRESS, key)
+end
+
+--------------------------------------------------
+-- Packet handlers
+--------------------------------------------------
+
+network.handlers = {}
+
+function network.on(id, callback)
+	network.handlers[id] = callback
+end
+
+--------------------------------------------------
+-- Receiving
+--------------------------------------------------
+
+local function receivePacket()
+	local lenData, err = client:receive(4)
+
+	if not lenData then
+		return nil
+	end
+
+	local length = unpackU32(lenData)
+
+	local idData = client:receive(2)
+	if not idData then
+		return nil
+	end
+
+	local msgID = unpackU16(idData)
+
+	local payload = ""
+
+	if length > 2 then
+		payload = client:receive(length - 2)
+
+		if not payload then
+			return nil
+		end
+	end
+
+	return msgID, payload
+end
+
+--------------------------------------------------
+-- Poll every frame
+--------------------------------------------------
+
+function network.update()
+	if not client then
+		return
+	end
+
+	while true do
+		local id, payload = receivePacket()
+
+		if not id then
+			break
+		end
+
+		local handler = network.handlers[id]
+
+		if handler then
+			handler(payload)
+		end
+	end
+end
+
+return network