Added source verification

src/config.go

@@ -61,8 +61,8 @@ func ipcGetOperation(device *Device, socket *bufio.ReadWriter) error {
 			if peer.endpoint != nil {
 				send("endpoint=" + peer.endpoint.String())
 			}
-			send(fmt.Sprintf("tx_bytes=%d", peer.tx_bytes))
-			send(fmt.Sprintf("rx_bytes=%d", peer.rx_bytes))
+			send(fmt.Sprintf("tx_bytes=%d", peer.txBytes))
+			send(fmt.Sprintf("rx_bytes=%d", peer.rxBytes))
 			send(fmt.Sprintf("persistent_keepalive_interval=%d", peer.persistentKeepaliveInterval))
 			for _, ip := range device.routingTable.AllowedIPs(peer) {
 				send("allowed_ip=" + ip.String())
@@ -73,7 +73,6 @@ func ipcGetOperation(device *Device, socket *bufio.ReadWriter) error {
 	// send lines
 
 	for _, line := range lines {
-		device.log.Debug.Println("Response:", line)
 		_, err := socket.WriteString(line + "\n")
 		if err != nil {
 			return err

src/device.go

@@ -31,10 +31,16 @@ type Device struct {
 	signal struct {
 		stop chan struct{}
 	}
-	peers map[NoisePublicKey]*Peer
-	mac   MACStateDevice
+	congestionState int32 // used as an atomic bool
+	peers           map[NoisePublicKey]*Peer
+	mac             MACStateDevice
 }
 
+const (
+	CongestionStateUnderLoad = iota
+	CongestionStateOkay
+)
+
 func (device *Device) SetPrivateKey(sk NoisePrivateKey) {
 	device.mutex.Lock()
 	defer device.mutex.Unlock()
@@ -93,6 +99,7 @@ func NewDevice(tun TUNDevice, logLevel int) *Device {
 		go device.RoutineDecryption()
 		go device.RoutineHandshake()
 	}
+	go device.RoutineBusyMonitor()
 	go device.RoutineReadFromTUN(tun)
 	go device.RoutineReceiveIncomming()
 	go device.RoutineWriteToTUN(tun)

src/peer.go

@@ -17,8 +17,8 @@ type Peer struct {
 	keyPairs                    KeyPairs
 	handshake                   Handshake
 	device                      *Device
-	tx_bytes                    uint64
-	rx_bytes                    uint64
+	txBytes                     uint64
+	rxBytes                     uint64
 	time                        struct {
 		lastSend      time.Time // last send message
 		lastHandshake time.Time // last completed handshake

src/receive.go

@@ -72,12 +72,48 @@ func addToHandshakeQueue(
 	}
 }
 
+/* Routine determining the busy state of the interface
+ *
+ * TODO: prehaps nicer to do this in response to events
+ * TODO: more well reasoned definition of "busy"
+ */
+func (device *Device) RoutineBusyMonitor() {
+	samples := 0
+	interval := time.Second
+	for timer := time.NewTimer(interval); ; {
+
+		select {
+		case <-device.signal.stop:
+			return
+		case <-timer.C:
+		}
+
+		// compute busy heuristic
+
+		if len(device.queue.handshake) > QueueHandshakeBusySize {
+			samples += 1
+		} else if samples > 0 {
+			samples -= 1
+		}
+		samples %= 30
+		busy := samples > 5
+
+		// update busy state
+
+		if busy {
+			atomic.StoreInt32(&device.congestionState, CongestionStateUnderLoad)
+		} else {
+			atomic.StoreInt32(&device.congestionState, CongestionStateOkay)
+		}
+
+		timer.Reset(interval)
+	}
+}
+
 func (device *Device) RoutineReceiveIncomming() {
 
-	debugLog := device.log.Debug
-	debugLog.Println("Routine, receive incomming, started")
-
-	errorLog := device.log.Error
+	logDebug := device.log.Debug
+	logDebug.Println("Routine, receive incomming, started")
 
 	var buffer []byte
 
@@ -122,33 +158,6 @@ func (device *Device) RoutineReceiveIncomming() {
 
 			case MessageInitiationType, MessageResponseType:
 
-				// verify mac1
-
-				if !device.mac.CheckMAC1(packet) {
-					debugLog.Println("Received packet with invalid mac1")
-					return
-				}
-
-				// check if busy, TODO: refine definition of "busy"
-
-				busy := len(device.queue.handshake) > QueueHandshakeBusySize
-				if busy && !device.mac.CheckMAC2(packet, raddr) {
-					sender := binary.LittleEndian.Uint32(packet[4:8]) // "sender" always follows "type"
-					reply, err := device.CreateMessageCookieReply(packet, sender, raddr)
-					if err != nil {
-						errorLog.Println("Failed to create cookie reply:", err)
-						return
-					}
-					writer := bytes.NewBuffer(packet[:0])
-					binary.Write(writer, binary.LittleEndian, reply)
-					packet = writer.Bytes()
-					_, err = device.net.conn.WriteToUDP(packet, raddr)
-					if err != nil {
-						debugLog.Println("Failed to send cookie reply:", err)
-					}
-					return
-				}
-
 				// add to handshake queue
 
 				addToHandshakeQueue(
@@ -173,7 +182,7 @@ func (device *Device) RoutineReceiveIncomming() {
 				reader := bytes.NewReader(packet)
 				err := binary.Read(reader, binary.LittleEndian, &reply)
 				if err != nil {
-					debugLog.Println("Failed to decode cookie reply")
+					logDebug.Println("Failed to decode cookie reply")
 					return
 				}
 				device.ConsumeMessageCookieReply(&reply)
@@ -218,7 +227,7 @@ func (device *Device) RoutineReceiveIncomming() {
 
 			default:
 				// unknown message type
-				debugLog.Println("Got unknown message from:", raddr)
+				logDebug.Println("Got unknown message from:", raddr)
 			}
 		}()
 	}
@@ -285,6 +294,38 @@ func (device *Device) RoutineHandshake() {
 
 		func() {
 
+			// verify mac1
+
+			if !device.mac.CheckMAC1(elem.packet) {
+				logDebug.Println("Received packet with invalid mac1")
+				return
+			}
+
+			// verify mac2
+
+			busy := atomic.LoadInt32(&device.congestionState) == CongestionStateUnderLoad
+
+			if busy && !device.mac.CheckMAC2(elem.packet, elem.source) {
+				sender := binary.LittleEndian.Uint32(elem.packet[4:8]) // "sender" always follows "type"
+				reply, err := device.CreateMessageCookieReply(elem.packet, sender, elem.source)
+				if err != nil {
+					logError.Println("Failed to create cookie reply:", err)
+					return
+				}
+				writer := bytes.NewBuffer(elem.packet[:0])
+				binary.Write(writer, binary.LittleEndian, reply)
+				elem.packet = writer.Bytes()
+				_, err = device.net.conn.WriteToUDP(elem.packet, elem.source)
+				if err != nil {
+					logDebug.Println("Failed to send cookie reply:", err)
+				}
+				return
+			}
+
+			// ratelimit
+
+			// handle messages
+
 			switch elem.msgType {
 			case MessageInitiationType:
 
@@ -321,12 +362,12 @@ func (device *Device) RoutineHandshake() {
 					logError.Println("Failed to create response message:", err)
 					return
 				}
+
 				outElem := device.NewOutboundElement()
 				writer := bytes.NewBuffer(outElem.data[:0])
 				binary.Write(writer, binary.LittleEndian, response)
 				elem.packet = writer.Bytes()
 				peer.mac.AddMacs(elem.packet)
-				device.log.Debug.Println(elem.packet)
 				addToOutboundQueue(peer.queue.outbound, outElem)
 
 			case MessageResponseType:
@@ -388,7 +429,7 @@ func (peer *Peer) RoutineSequentialReceiver() {
 		}
 		elem.mutex.Lock()
 
-		// process IP packet
+		// process packet
 
 		func() {
 			if elem.IsDropped() {
@@ -407,30 +448,54 @@ func (peer *Peer) RoutineSequentialReceiver() {
 				return
 			}
 
-			// strip padding
+			// verify source and strip padding
 
 			switch elem.packet[0] >> 4 {
 			case IPv4version:
+
+				// strip padding
+
 				if len(elem.packet) < IPv4headerSize {
 					return
 				}
+
 				field := elem.packet[IPv4offsetTotalLength : IPv4offsetTotalLength+2]
 				length := binary.BigEndian.Uint16(field)
 				elem.packet = elem.packet[:length]
 
+				// verify IPv4 source
+
+				dst := elem.packet[IPv4offsetDst : IPv4offsetDst+net.IPv4len]
+				if device.routingTable.LookupIPv4(dst) != peer {
+					return
+				}
+
 			case IPv6version:
+
+				// strip padding
+
 				if len(elem.packet) < IPv6headerSize {
 					return
 				}
+
 				field := elem.packet[IPv6offsetPayloadLength : IPv6offsetPayloadLength+2]
 				length := binary.BigEndian.Uint16(field)
 				length += IPv6headerSize
 				elem.packet = elem.packet[:length]
 
+				// verify IPv6 source
+
+				dst := elem.packet[IPv6offsetDst : IPv6offsetDst+net.IPv6len]
+				if device.routingTable.LookupIPv6(dst) != peer {
+					return
+				}
+
 			default:
 				device.log.Debug.Println("Receieved packet with unknown IP version")
 				return
 			}
+
+			atomic.AddUint64(&peer.rxBytes, uint64(len(elem.packet)))
 			addToInboundQueue(device.queue.inbound, elem)
 		}()
 	}

src/send.go

@@ -329,7 +329,7 @@ func (peer *Peer) RoutineSequentialSender() {
 				if err != nil {
 					return
 				}
-				atomic.AddUint64(&peer.tx_bytes, uint64(len(work.packet)))
+				atomic.AddUint64(&peer.txBytes, uint64(len(work.packet)))
 
 				// shift keep-alive timer