Improved readability of send/receive code

2 files changed, 178 insertions, 218 deletions

diff --git a/src/receive.go b/src/receive.go
index 97646d8..09fca77 100644
--- a/src/receive.go
+++ b/src/receive.go
@@ -128,7 +128,7 @@ func (device *Device) RoutineReceiveIncomming() {
 
 				// read next datagram
 
-				size, raddr, err := conn.ReadFromUDP(buffer[:]) // Blocks sometimes
+				size, raddr, err := conn.ReadFromUDP(buffer[:])
 
 				if err != nil {
 					break
@@ -222,7 +222,7 @@ func (device *Device) RoutineReceiveIncomming() {
 }
 
 func (device *Device) RoutineDecryption() {
-	var elem *QueueInboundElement
+
 	var nonce [chacha20poly1305.NonceSize]byte
 
 	logDebug := device.log.Debug
@@ -230,50 +230,51 @@ func (device *Device) RoutineDecryption() {
 
 	for {
 		select {
-		case elem = <-device.queue.decryption:
 		case <-device.signal.stop:
+			logDebug.Println("Routine, decryption worker, stopped")
 			return
-		}
 
-		// check if dropped
+		case elem := <-device.queue.decryption:
 
-		if elem.IsDropped() {
-			continue
-		}
+			// check if dropped
 
-		// split message into fields
-
-		counter := elem.packet[MessageTransportOffsetCounter:MessageTransportOffsetContent]
-		content := elem.packet[MessageTransportOffsetContent:]
-
-		// decrypt with key-pair
-
-		var err error
-		copy(nonce[4:], counter)
-		elem.counter = binary.LittleEndian.Uint64(counter)
-		elem.keyPair.receive.mutex.RLock()
-		if elem.keyPair.receive.aead == nil {
-			// very unlikely (the key was deleted during queuing)
-			elem.Drop()
-		} else {
-			elem.packet, err = elem.keyPair.receive.aead.Open(
-				elem.buffer[:0],
-				nonce[:],
-				content,
-				nil,
-			)
-			if err != nil {
+			if elem.IsDropped() {
+				continue
+			}
+
+			// split message into fields
+
+			counter := elem.packet[MessageTransportOffsetCounter:MessageTransportOffsetContent]
+			content := elem.packet[MessageTransportOffsetContent:]
+
+			// decrypt with key-pair
+
+			copy(nonce[4:], counter)
+			elem.counter = binary.LittleEndian.Uint64(counter)
+			elem.keyPair.receive.mutex.RLock()
+			if elem.keyPair.receive.aead == nil {
+				// very unlikely (the key was deleted during queuing)
 				elem.Drop()
+			} else {
+				var err error
+				elem.packet, err = elem.keyPair.receive.aead.Open(
+					elem.buffer[:0],
+					nonce[:],
+					content,
+					nil,
+				)
+				if err != nil {
+					elem.Drop()
+				}
 			}
+
+			elem.keyPair.receive.mutex.RUnlock()
+			elem.mutex.Unlock()
 		}
-		elem.keyPair.receive.mutex.RUnlock()
-		elem.mutex.Unlock()
 	}
 }
 
 /* Handles incomming packets related to handshake
- *
- *
  */
 func (device *Device) RoutineHandshake() {
 
@@ -473,7 +474,6 @@ func (device *Device) RoutineHandshake() {
 }
 
 func (peer *Peer) RoutineSequentialReceiver() {
-	var elem *QueueInboundElement
 
 	device := peer.device
 
@@ -483,118 +483,119 @@ func (peer *Peer) RoutineSequentialReceiver() {
 	logDebug.Println("Routine, sequential receiver, started for peer", peer.id)
 
 	for {
-		// wait for decryption
 
 		select {
 		case <-peer.signal.stop:
+			logDebug.Println("Routine, sequential receiver, stopped for peer", peer.id)
 			return
-		case elem = <-peer.queue.inbound:
-		}
-		elem.mutex.Lock()
 
-		// process packet
+		case elem := <-peer.queue.inbound:
 
-		if elem.IsDropped() {
-			continue
-		}
+			// wait for decryption
+
+			elem.mutex.Lock()
+			if elem.IsDropped() {
+				continue
+			}
 
-		// check for replay
+			// check for replay
 
-		if !elem.keyPair.replayFilter.ValidateCounter(elem.counter) {
-			continue
-		}
+			if !elem.keyPair.replayFilter.ValidateCounter(elem.counter) {
+				continue
+			}
 
-		peer.TimerAnyAuthenticatedPacketTraversal()
-		peer.TimerAnyAuthenticatedPacketReceived()
-		peer.KeepKeyFreshReceiving()
+			peer.TimerAnyAuthenticatedPacketTraversal()
+			peer.TimerAnyAuthenticatedPacketReceived()
+			peer.KeepKeyFreshReceiving()
 
-		// check if using new key-pair
+			// check if using new key-pair
 
-		kp := &peer.keyPairs
-		kp.mutex.Lock()
-		if kp.next == elem.keyPair {
-			peer.TimerHandshakeComplete()
-			if kp.previous != nil {
-				device.DeleteKeyPair(kp.previous)
+			kp := &peer.keyPairs
+			kp.mutex.Lock()
+			if kp.next == elem.keyPair {
+				peer.TimerHandshakeComplete()
+				if kp.previous != nil {
+					device.DeleteKeyPair(kp.previous)
+				}
+				kp.previous = kp.current
+				kp.current = kp.next
+				kp.next = nil
 			}
-			kp.previous = kp.current
-			kp.current = kp.next
-			kp.next = nil
-		}
-		kp.mutex.Unlock()
+			kp.mutex.Unlock()
 
-		// check for keep-alive
+			// check for keep-alive
 
-		if len(elem.packet) == 0 {
-			logDebug.Println("Received keep-alive from", peer.String())
-			continue
-		}
-		peer.TimerDataReceived()
+			if len(elem.packet) == 0 {
+				logDebug.Println("Received keep-alive from", peer.String())
+				continue
+			}
+			peer.TimerDataReceived()
 
-		// verify source and strip padding
+			// verify source and strip padding
 
-		switch elem.packet[0] >> 4 {
-		case ipv4.Version:
+			switch elem.packet[0] >> 4 {
+			case ipv4.Version:
 
-			// strip padding
+				// strip padding
 
-			if len(elem.packet) < ipv4.HeaderLen {
-				continue
-			}
+				if len(elem.packet) < ipv4.HeaderLen {
+					continue
+				}
 
-			field := elem.packet[IPv4offsetTotalLength : IPv4offsetTotalLength+2]
-			length := binary.BigEndian.Uint16(field)
-			if int(length) > len(elem.packet) || int(length) < ipv4.HeaderLen {
-				continue
-			}
+				field := elem.packet[IPv4offsetTotalLength : IPv4offsetTotalLength+2]
+				length := binary.BigEndian.Uint16(field)
+				if int(length) > len(elem.packet) || int(length) < ipv4.HeaderLen {
+					continue
+				}
 
-			elem.packet = elem.packet[:length]
+				elem.packet = elem.packet[:length]
 
-			// verify IPv4 source
+				// verify IPv4 source
 
-			src := elem.packet[IPv4offsetSrc : IPv4offsetSrc+net.IPv4len]
-			if device.routingTable.LookupIPv4(src) != peer {
-				logInfo.Println("Packet with unallowed source IP from", peer.String())
-				continue
-			}
+				src := elem.packet[IPv4offsetSrc : IPv4offsetSrc+net.IPv4len]
+				if device.routingTable.LookupIPv4(src) != peer {
+					logInfo.Println("Packet with unallowed source IP from", peer.String())
+					continue
+				}
 
-		case ipv6.Version:
+			case ipv6.Version:
 
-			// strip padding
+				// strip padding
 
-			if len(elem.packet) < ipv6.HeaderLen {
-				continue
-			}
+				if len(elem.packet) < ipv6.HeaderLen {
+					continue
+				}
 
-			field := elem.packet[IPv6offsetPayloadLength : IPv6offsetPayloadLength+2]
-			length := binary.BigEndian.Uint16(field)
-			length += ipv6.HeaderLen
-			if int(length) > len(elem.packet) {
-				continue
-			}
+				field := elem.packet[IPv6offsetPayloadLength : IPv6offsetPayloadLength+2]
+				length := binary.BigEndian.Uint16(field)
+				length += ipv6.HeaderLen
+				if int(length) > len(elem.packet) {
+					continue
+				}
 
-			elem.packet = elem.packet[:length]
+				elem.packet = elem.packet[:length]
 
-			// verify IPv6 source
+				// verify IPv6 source
+
+				src := elem.packet[IPv6offsetSrc : IPv6offsetSrc+net.IPv6len]
+				if device.routingTable.LookupIPv6(src) != peer {
+					logInfo.Println("Packet with unallowed source IP from", peer.String())
+					continue
+				}
 
-			src := elem.packet[IPv6offsetSrc : IPv6offsetSrc+net.IPv6len]
-			if device.routingTable.LookupIPv6(src) != peer {
-				logInfo.Println("Packet with unallowed source IP from", peer.String())
+			default:
+				logInfo.Println("Packet with invalid IP version from", peer.String())
 				continue
 			}
 
-		default:
-			logInfo.Println("Packet with invalid IP version from", peer.String())
-			continue
-		}
-
-		// write to tun
+			// write to tun
 
-		atomic.AddUint64(&peer.stats.rxBytes, uint64(len(elem.packet)))
-		_, err := device.tun.device.Write(elem.packet)
-		device.PutMessageBuffer(elem.buffer)
-		if err != nil {
-			logError.Println("Failed to write packet to TUN device:", err)
+			atomic.AddUint64(&peer.stats.rxBytes, uint64(len(elem.packet)))
+			_, err := device.tun.device.Write(elem.packet)
+			device.PutMessageBuffer(elem.buffer)
+			if err != nil {
+				logError.Println("Failed to write packet to TUN device:", err)
+			}
 		}
 	}
 }
diff --git a/src/send.go b/src/send.go
index c598ad4..e9dfb54 100644
--- a/src/send.go
+++ b/src/send.go
@@ -35,7 +35,7 @@ type QueueOutboundElement struct {
 	dropped int32
 	mutex   sync.Mutex
 	buffer  *[MaxMessageSize]byte // slice holding the packet data
-	packet  []byte                // slice of "data" (always!)
+	packet  []byte                // slice of "buffer" (always!)
 	nonce   uint64                // nonce for encryption
 	keyPair *KeyPair              // key-pair for encryption
 	peer    *Peer                 // related peer
@@ -52,11 +52,6 @@ func (peer *Peer) FlushNonceQueue() {
 	}
 }
 
-var (
-	ErrorNoEndpoint   = errors.New("No known endpoint for peer")
-	ErrorNoConnection = errors.New("No UDP socket for device")
-)
-
 func (device *Device) NewOutboundElement() *QueueOutboundElement {
 	return &QueueOutboundElement{
 		dropped: AtomicFalse,
@@ -118,14 +113,13 @@ func (peer *Peer) SendBuffer(buffer []byte) (int, error) {
 	defer peer.mutex.RUnlock()
 
 	endpoint := peer.endpoint
-	conn := peer.device.net.conn
-
 	if endpoint == nil {
-		return 0, ErrorNoEndpoint
+		return 0, errors.New("No known endpoint for peer")
 	}
 
+	conn := peer.device.net.conn
 	if conn == nil {
-		return 0, ErrorNoConnection
+		return 0, errors.New("No UDP socket for device")
 	}
 
 	return conn.WriteToUDP(buffer, endpoint)
@@ -189,16 +183,6 @@ func (device *Device) RoutineReadFromTUN() {
 			continue
 		}
 
-		// check if known endpoint (drop early)
-
-		peer.mutex.RLock()
-		if peer.endpoint == nil {
-			peer.mutex.RUnlock()
-			logDebug.Println("No known endpoint for peer", peer.String())
-			continue
-		}
-		peer.mutex.RUnlock()
-
 		// insert into nonce/pre-handshake queue
 
 		signalSend(peer.signal.handshakeReset)
@@ -211,86 +195,61 @@ func (device *Device) RoutineReadFromTUN() {
  * Then assigns nonces to packets sequentially
  * and creates "work" structs for workers
  *
- * TODO: Avoid dynamic allocation of work queue elements
- *
  * Obs. A single instance per peer
  */
 func (peer *Peer) RoutineNonce() {
 	var keyPair *KeyPair
-	var elem *QueueOutboundElement
 
 	device := peer.device
 	logDebug := device.log.Debug
 	logDebug.Println("Routine, nonce worker, started for peer", peer.String())
 
-	func() {
-
-		for {
-		NextPacket:
-
-			// wait for packet
+	for {
+	NextPacket:
+		select {
+		case <-peer.signal.stop:
+			return
 
-			if elem == nil {
-				select {
-				case elem = <-peer.queue.nonce:
-				case <-peer.signal.stop:
-					return
-				}
-			}
+		case elem := <-peer.queue.nonce:
 
 			// wait for key pair
 
 			for {
-				select {
-				case <-peer.signal.newKeyPair:
-				default:
-				}
-
 				keyPair = peer.keyPairs.Current()
 				if keyPair != nil && keyPair.sendNonce < RejectAfterMessages {
 					if time.Now().Sub(keyPair.created) < RejectAfterTime {
 						break
 					}
 				}
+
 				signalSend(peer.signal.handshakeBegin)
 				logDebug.Println("Awaiting key-pair for", peer.String())
 
 				select {
 				case <-peer.signal.newKeyPair:
-					logDebug.Println("Key-pair negotiated for", peer.String())
-					goto NextPacket
-
 				case <-peer.signal.flushNonceQueue:
 					logDebug.Println("Clearing queue for", peer.String())
 					peer.FlushNonceQueue()
-					elem = nil
 					goto NextPacket
-
 				case <-peer.signal.stop:
 					return
 				}
 			}
 
-			// process current packet
+			// populate work element
 
-			if elem != nil {
-
-				// create work element
-
-				elem.keyPair = keyPair
-				elem.nonce = atomic.AddUint64(&keyPair.sendNonce, 1) - 1
-				elem.dropped = AtomicFalse
-				elem.peer = peer
-				elem.mutex.Lock()
+			elem.peer = peer
+			elem.nonce = atomic.AddUint64(&keyPair.sendNonce, 1) - 1
+			elem.keyPair = keyPair
+			elem.dropped = AtomicFalse
+			elem.mutex.Lock()
 
-				// add to parallel and sequential queue
+			// add to parallel and sequential queue
 
-				addToEncryptionQueue(device.queue.encryption, elem)
-				addToOutboundQueue(peer.queue.outbound, elem)
-				elem = nil
-			}
+			addToEncryptionQueue(device.queue.encryption, elem)
+			addToOutboundQueue(peer.queue.outbound, elem)
 		}
-	}()
+	}
 }
 
 /* Encrypts the elements in the queue
@@ -300,7 +259,6 @@ func (peer *Peer) RoutineNonce() {
  */
 func (device *Device) RoutineEncryption() {
 
-	var elem *QueueOutboundElement
 	var nonce [chacha20poly1305.NonceSize]byte
 
 	logDebug := device.log.Debug
@@ -311,62 +269,62 @@ func (device *Device) RoutineEncryption() {
 		// fetch next element
 
 		select {
-		case elem = <-device.queue.encryption:
 		case <-device.signal.stop:
 			logDebug.Println("Routine, encryption worker, stopped")
 			return
-		}
 
-		// check if dropped
+		case elem := <-device.queue.encryption:
 
-		if elem.IsDropped() {
-			continue
-		}
+			// check if dropped
+
+			if elem.IsDropped() {
+				continue
+			}
 
-		// populate header fields
+			// populate header fields
 
-		header := elem.buffer[:MessageTransportHeaderSize]
+			header := elem.buffer[:MessageTransportHeaderSize]
 
-		fieldType := header[0:4]
-		fieldReceiver := header[4:8]
-		fieldNonce := header[8:16]
+			fieldType := header[0:4]
+			fieldReceiver := header[4:8]
+			fieldNonce := header[8:16]
 
-		binary.LittleEndian.PutUint32(fieldType, MessageTransportType)
-		binary.LittleEndian.PutUint32(fieldReceiver, elem.keyPair.remoteIndex)
-		binary.LittleEndian.PutUint64(fieldNonce, elem.nonce)
+			binary.LittleEndian.PutUint32(fieldType, MessageTransportType)
+			binary.LittleEndian.PutUint32(fieldReceiver, elem.keyPair.remoteIndex)
+			binary.LittleEndian.PutUint64(fieldNonce, elem.nonce)
 
-		// pad content to MTU size
+			// pad content to multiple of 16
 
-		mtu := int(atomic.LoadInt32(&device.tun.mtu))
-		pad := len(elem.packet) % PaddingMultiple
-		if pad > 0 {
-			for i := 0; i < PaddingMultiple-pad && len(elem.packet) < mtu; i++ {
-				elem.packet = append(elem.packet, 0)
+			mtu := int(atomic.LoadInt32(&device.tun.mtu))
+			rem := len(elem.packet) % PaddingMultiple
+			if rem > 0 {
+				for i := 0; i < PaddingMultiple-rem && len(elem.packet) < mtu; i++ {
+					elem.packet = append(elem.packet, 0)
+				}
 			}
-			// TODO: How good is this code
-		}
 
-		// encrypt content (append to header)
-
-		binary.LittleEndian.PutUint64(nonce[4:], elem.nonce)
-		elem.keyPair.send.mutex.RLock()
-		if elem.keyPair.send.aead == nil {
-			// very unlikely (the key was deleted during queuing)
-			elem.Drop()
-		} else {
-			elem.packet = elem.keyPair.send.aead.Seal(
-				header,
-				nonce[:],
-				elem.packet,
-				nil,
-			)
-		}
-		elem.keyPair.send.mutex.RUnlock()
-		elem.mutex.Unlock()
+			// encrypt content (append to header)
+
+			binary.LittleEndian.PutUint64(nonce[4:], elem.nonce)
+			elem.keyPair.send.mutex.RLock()
+			if elem.keyPair.send.aead == nil {
+				// very unlikely (the key was deleted during queuing)
+				elem.Drop()
+			} else {
+				elem.packet = elem.keyPair.send.aead.Seal(
+					header,
+					nonce[:],
+					elem.packet,
+					nil,
+				)
+			}
+			elem.mutex.Unlock()
+			elem.keyPair.send.mutex.RUnlock()
 
-		// refresh key if necessary
+			// refresh key if necessary
 
-		elem.peer.KeepKeyFreshSending()
+			elem.peer.KeepKeyFreshSending()
+		}
 	}
 }
 
@@ -399,6 +357,7 @@ func (peer *Peer) RoutineSequentialSender() {
 			_, err := peer.SendBuffer(elem.packet)
 			device.PutMessageBuffer(elem.buffer)
 			if err != nil {
+				logDebug.Println("Failed to send authenticated packet to peer", peer.String())
 				continue
 			}
 			atomic.AddUint64(&peer.stats.txBytes, length)