Fixed cookie reply processing bug

10 files changed, 173 insertions, 95 deletions

diff --git a/src/constants.go b/src/constants.go
index 053ba4f..6fbb7a0 100644
--- a/src/constants.go
+++ b/src/constants.go
@@ -12,7 +12,7 @@ const (
 	RejectAfterTime         = time.Second * 180
 	RejectAfterMessages     = (1 << 64) - (1 << 4) - 1
 	KeepaliveTimeout        = time.Second * 10
-	CookieRefreshTime       = time.Second * 2
+	CookieRefreshTime       = time.Minute * 2
 	MaxHandshakeAttemptTime = time.Second * 90
 )
 
diff --git a/src/device.go b/src/device.go
index c577623..882d587 100644
--- a/src/device.go
+++ b/src/device.go
@@ -25,8 +25,8 @@ type Device struct {
 	queue        struct {
 		encryption chan *QueueOutboundElement
 		decryption chan *QueueInboundElement
+		inbound    chan *QueueInboundElement
 		handshake  chan QueueHandshakeElement
-		inbound    chan []byte // inbound queue for TUN
 	}
 	signal struct {
 		stop chan struct{}
@@ -77,10 +77,10 @@ func NewDevice(tun TUNDevice, logLevel int) *Device {
 
 	// create queues
 
-	device.queue.encryption = make(chan *QueueOutboundElement, QueueOutboundSize)
 	device.queue.handshake = make(chan QueueHandshakeElement, QueueHandshakeSize)
+	device.queue.encryption = make(chan *QueueOutboundElement, QueueOutboundSize)
 	device.queue.decryption = make(chan *QueueInboundElement, QueueInboundSize)
-	device.queue.inbound = make(chan []byte, QueueInboundSize)
+	device.queue.inbound = make(chan *QueueInboundElement, QueueInboundSize)
 
 	// prepare signals
 
diff --git a/src/handshake.go b/src/handshake.go
index 88bb8cb..de607df 100644
--- a/src/handshake.go
+++ b/src/handshake.go
@@ -112,7 +112,6 @@ func (peer *Peer) RoutineHandshakeInitiator() {
 				binary.Write(writer, binary.LittleEndian, msg)
 				elem.packet = writer.Bytes()
 				peer.mac.AddMacs(elem.packet)
-				println(elem)
 				addToOutboundQueue(peer.queue.outbound, elem)
 
 				if attempts == 0 {
diff --git a/src/ip.go b/src/ip.go
index a9685ad..36beb9c 100644
--- a/src/ip.go
+++ b/src/ip.go
@@ -5,14 +5,17 @@ import (
 )
 
 const (
-	IPv4version    = 4
-	IPv4offsetSrc  = 12
-	IPv4offsetDst  = IPv4offsetSrc + net.IPv4len
-	IPv4headerSize = 20
+	IPv4version           = 4
+	IPv4offsetTotalLength = 2
+	IPv4offsetSrc         = 12
+	IPv4offsetDst         = IPv4offsetSrc + net.IPv4len
+	IPv4headerSize        = 20
 )
 
 const (
-	IPv6version   = 6
-	IPv6offsetSrc = 8
-	IPv6offsetDst = IPv6offsetSrc + net.IPv6len
+	IPv6version             = 6
+	IPv6offsetPayloadLength = 4
+	IPv6offsetSrc           = 8
+	IPv6offsetDst           = IPv6offsetSrc + net.IPv6len
+	IPv6headerSize          = 40
 )
diff --git a/src/macs_device.go b/src/macs_device.go
index deac803..68181e6 100644
--- a/src/macs_device.go
+++ b/src/macs_device.go
@@ -15,21 +15,31 @@ type MACStateDevice struct {
 	mutex     sync.RWMutex
 	refreshed time.Time
 	secret    [blake2s.Size]byte
-	keyMac1   [blake2s.Size]byte
+	keyMAC1   [blake2s.Size]byte
+	keyMAC2   [blake2s.Size]byte
 	xaead     cipher.AEAD
 }
 
 func (state *MACStateDevice) Init(pk NoisePublicKey) {
 	state.mutex.Lock()
 	defer state.mutex.Unlock()
+
 	func() {
 		hsh, _ := blake2s.New256(nil)
 		hsh.Write([]byte(WGLabelMAC1))
 		hsh.Write(pk[:])
-		hsh.Sum(state.keyMac1[:0])
+		hsh.Sum(state.keyMAC1[:0])
 	}()
-	state.xaead, _ = chacha20poly1305.NewXCipher(state.keyMac1[:])
-	state.refreshed = time.Time{} // never
+
+	func() {
+		hsh, _ := blake2s.New256(nil)
+		hsh.Write([]byte(WGLabelCookie))
+		hsh.Write(pk[:])
+		hsh.Sum(state.keyMAC2[:0])
+	}()
+
+	state.xaead, _ = chacha20poly1305.NewXCipher(state.keyMAC2[:])
+	state.refreshed = time.Time{}
 }
 
 func (state *MACStateDevice) CheckMAC1(msg []byte) bool {
@@ -39,7 +49,7 @@ func (state *MACStateDevice) CheckMAC1(msg []byte) bool {
 
 	var mac1 [blake2s.Size128]byte
 	func() {
-		mac, _ := blake2s.New128(state.keyMac1[:])
+		mac, _ := blake2s.New128(state.keyMAC1[:])
 		mac.Write(msg[:startMac1])
 		mac.Sum(mac1[:0])
 	}()
@@ -117,7 +127,7 @@ func (device *Device) CreateMessageCookieReply(msg []byte, receiver uint32, addr
 	startMac1 := size - (blake2s.Size128 * 2)
 	startMac2 := size - blake2s.Size128
 
-	M := msg[startMac1:startMac2]
+	mac1 := msg[startMac1:startMac2]
 
 	reply := new(MessageCookieReply)
 	reply.Type = MessageCookieReplyType
@@ -127,7 +137,7 @@ func (device *Device) CreateMessageCookieReply(msg []byte, receiver uint32, addr
 		state.mutex.RUnlock()
 		return nil, err
 	}
-	state.xaead.Seal(reply.Cookie[:0], reply.Nonce[:], cookie[:], M)
+	state.xaead.Seal(reply.Cookie[:0], reply.Nonce[:], cookie[:], mac1)
 	state.mutex.RUnlock()
 	return reply, nil
 }
@@ -149,9 +159,11 @@ func (device *Device) ConsumeMessageCookieReply(msg *MessageCookieReply) bool {
 
 	var cookie [blake2s.Size128]byte
 	state := &lookup.peer.mac
+
 	state.mutex.Lock()
 	defer state.mutex.Unlock()
-	_, err := state.xaead.Open(cookie[:0], msg.Nonce[:], msg.Cookie[:], state.lastMac1[:])
+
+	_, err := state.xaead.Open(cookie[:0], msg.Nonce[:], msg.Cookie[:], state.lastMAC1[:])
 	if err != nil {
 		return false
 	}
diff --git a/src/macs_peer.go b/src/macs_peer.go
index 5e9ebae..16a7a87 100644
--- a/src/macs_peer.go
+++ b/src/macs_peer.go
@@ -13,21 +13,31 @@ type MACStatePeer struct {
 	mutex     sync.RWMutex
 	cookieSet time.Time
 	cookie    [blake2s.Size128]byte
-	lastMac1  [blake2s.Size128]byte
-	keyMac1   [blake2s.Size]byte
+	lastMAC1  [blake2s.Size128]byte
+	keyMAC1   [blake2s.Size]byte
+	keyMAC2   [blake2s.Size]byte
 	xaead     cipher.AEAD
 }
 
 func (state *MACStatePeer) Init(pk NoisePublicKey) {
 	state.mutex.Lock()
 	defer state.mutex.Unlock()
+
 	func() {
 		hsh, _ := blake2s.New256(nil)
 		hsh.Write([]byte(WGLabelMAC1))
 		hsh.Write(pk[:])
-		hsh.Sum(state.keyMac1[:0])
+		hsh.Sum(state.keyMAC1[:0])
 	}()
-	state.xaead, _ = chacha20poly1305.NewXCipher(state.keyMac1[:])
+
+	func() {
+		hsh, _ := blake2s.New256(nil)
+		hsh.Write([]byte(WGLabelCookie))
+		hsh.Write(pk[:])
+		hsh.Sum(state.keyMAC2[:0])
+	}()
+
+	state.xaead, _ = chacha20poly1305.NewXCipher(state.keyMAC2[:])
 	state.cookieSet = time.Time{} // never
 }
 
@@ -50,11 +60,11 @@ func (state *MACStatePeer) AddMacs(msg []byte) {
 	// set mac1
 
 	func() {
-		mac, _ := blake2s.New128(state.keyMac1[:])
+		mac, _ := blake2s.New128(state.keyMAC1[:])
 		mac.Write(msg[:startMac1])
-		mac.Sum(state.lastMac1[:0])
+		mac.Sum(state.lastMAC1[:0])
 	}()
-	copy(mac1, state.lastMac1[:])
+	copy(mac1, state.lastMAC1[:])
 
 	// set mac2
 
diff --git a/src/macs_test.go b/src/macs_test.go
index a2a6503..b7d5115 100644
--- a/src/macs_test.go
+++ b/src/macs_test.go
@@ -1,7 +1,6 @@
 package main
 
 import (
-	"bytes"
 	"net"
 	"testing"
 	"testing/quick"
@@ -17,8 +16,8 @@ func TestMAC1(t *testing.T) {
 	peer1 := dev2.NewPeer(dev1.privateKey.publicKey())
 	peer2 := dev1.NewPeer(dev2.privateKey.publicKey())
 
-	assertEqual(t, peer1.mac.keyMac1[:], dev1.mac.keyMac1[:])
-	assertEqual(t, peer2.mac.keyMac1[:], dev2.mac.keyMac1[:])
+	assertEqual(t, peer1.mac.keyMAC1[:], dev1.mac.keyMAC1[:])
+	assertEqual(t, peer2.mac.keyMAC1[:], dev2.mac.keyMAC1[:])
 
 	msg1 := make([]byte, 256)
 	copy(msg1, []byte("some content"))
@@ -52,17 +51,15 @@ func TestMACs(t *testing.T) {
 		if addr.Port < 0 {
 			return true
 		}
+
 		addr.Port &= 0xffff
 
 		if len(msg) < 32 {
 			return true
 		}
-		if bytes.Compare(peer1.mac.keyMac1[:], device1.mac.keyMac1[:]) != 0 {
-			return false
-		}
-		if bytes.Compare(peer2.mac.keyMac1[:], device2.mac.keyMac1[:]) != 0 {
-			return false
-		}
+
+		assertEqual(t, peer1.mac.keyMAC1[:], device1.mac.keyMAC1[:])
+		assertEqual(t, peer2.mac.keyMAC1[:], device2.mac.keyMAC1[:])
 
 		device2.indices.Insert(receiver, IndexTableEntry{
 			peer:      peer1,
@@ -83,17 +80,17 @@ func TestMACs(t *testing.T) {
 			return false
 		}
 
-		if device2.ConsumeMessageCookieReply(cr) == false {
+		if !device2.ConsumeMessageCookieReply(cr) {
 			return false
 		}
 
 		// test MAC1 + MAC2
 
 		peer1.mac.AddMacs(msg)
-		if device1.mac.CheckMAC1(msg) == false {
+		if !device1.mac.CheckMAC1(msg) {
 			return false
 		}
-		if device1.mac.CheckMAC2(msg, &addr) == false {
+		if !device1.mac.CheckMAC2(msg, &addr) {
 			return false
 		}
 
@@ -107,6 +104,8 @@ func TestMACs(t *testing.T) {
 			return false
 		}
 
+		t.Log("Passed")
+
 		return true
 	}
 
diff --git a/src/receive.go b/src/receive.go
index 50789a1..7b16dc5 100644
--- a/src/receive.go
+++ b/src/receive.go
@@ -55,6 +55,23 @@ func addToInboundQueue(
 	}
 }
 
+func addToHandshakeQueue(
+	queue chan QueueHandshakeElement,
+	element QueueHandshakeElement,
+) {
+	for {
+		select {
+		case queue <- element:
+			return
+		default:
+			select {
+			case <-queue:
+			default:
+			}
+		}
+	}
+}
+
 func (device *Device) RoutineReceiveIncomming() {
 
 	debugLog := device.log.Debug
@@ -62,7 +79,7 @@ func (device *Device) RoutineReceiveIncomming() {
 
 	errorLog := device.log.Error
 
-	var buffer []byte // unsliced buffer
+	var buffer []byte
 
 	for {
 
@@ -116,7 +133,7 @@ func (device *Device) RoutineReceiveIncomming() {
 
 				busy := len(device.queue.handshake) > QueueHandshakeBusySize
 				if busy && !device.mac.CheckMAC2(packet, raddr) {
-					sender := binary.LittleEndian.Uint32(packet[4:8]) // "sender" follows "type"
+					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)
@@ -134,12 +151,15 @@ func (device *Device) RoutineReceiveIncomming() {
 
 				// add to handshake queue
 
+				addToHandshakeQueue(
+					device.queue.handshake,
+					QueueHandshakeElement{
+						msgType: msgType,
+						packet:  packet,
+						source:  raddr,
+					},
+				)
 				buffer = nil
-				device.queue.handshake <- QueueHandshakeElement{
-					msgType: msgType,
-					packet:  packet,
-					source:  raddr,
-				}
 
 			case MessageCookieReplyType:
 
@@ -293,7 +313,21 @@ func (device *Device) RoutineHandshake() {
 					)
 					return
 				}
-				logDebug.Println("Recieved valid initiation message for peer", peer.id)
+
+				// create response
+
+				response, err := device.CreateMessageResponse(peer)
+				if err != nil {
+					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:
 
@@ -352,29 +386,53 @@ func (peer *Peer) RoutineSequentialReceiver() {
 			return
 		case elem = <-peer.queue.inbound:
 		}
-
 		elem.mutex.Lock()
-		if elem.IsDropped() {
-			continue
-		}
 
-		// check for replay
+		// process IP packet
+
+		func() {
+			if elem.IsDropped() {
+				return
+			}
 
-		// update timers
+			// check for replay
 
-		// check for keep-alive
+			// update timers
 
-		if len(elem.packet) == 0 {
-			continue
-		}
+			// refresh key material
 
-		// strip padding
+			// check for keep-alive
 
-		// insert into inbound TUN queue
+			if len(elem.packet) == 0 {
+				return
+			}
 
-		device.queue.inbound <- elem.packet
+			// strip padding
 
-		// update key material
+			switch elem.packet[0] >> 4 {
+			case IPv4version:
+				if len(elem.packet) < IPv4headerSize {
+					return
+				}
+				field := elem.packet[IPv4offsetTotalLength : IPv4offsetTotalLength+2]
+				length := binary.BigEndian.Uint16(field)
+				elem.packet = elem.packet[:length]
+
+			case IPv6version:
+				if len(elem.packet) < IPv6headerSize {
+					return
+				}
+				field := elem.packet[IPv6offsetPayloadLength : IPv6offsetPayloadLength+2]
+				length := binary.BigEndian.Uint16(field)
+				length += IPv6headerSize
+				elem.packet = elem.packet[:length]
+
+			default:
+				device.log.Debug.Println("Receieved packet with unknown IP version")
+				return
+			}
+			addToInboundQueue(device.queue.inbound, elem)
+		}()
 	}
 }
 
@@ -387,8 +445,8 @@ func (device *Device) RoutineWriteToTUN(tun TUNDevice) {
 		select {
 		case <-device.signal.stop:
 			return
-		case packet := <-device.queue.inbound:
-			_, err := tun.Write(packet)
+		case elem := <-device.queue.inbound:
+			_, err := tun.Write(elem.packet)
 			if err != nil {
 				logError.Println("Failed to write packet to TUN device:", err)
 			}
diff --git a/src/send.go b/src/send.go
index 4053669..d1de44a 100644
--- a/src/send.go
+++ b/src/send.go
@@ -28,13 +28,13 @@ import (
  *
  * If the element is inserted into the "encryption queue",
  * the content is preceeded by enough "junk" to contain the header
- * (to allow the constuction of transport messages in-place)
+ * (to allow the construction of transport messages in-place)
  */
 type QueueOutboundElement struct {
 	state   uint32
 	mutex   sync.Mutex
 	data    [MaxMessageSize]byte
-	packet  []byte   // slice of packet (sending)
+	packet  []byte   // slice of "data" (always!)
 	nonce   uint64   // nonce for encryption
 	keyPair *KeyPair // key-pair for encryption
 	peer    *Peer    // related peer
@@ -51,8 +51,12 @@ func (peer *Peer) FlushNonceQueue() {
 	}
 }
 
+/*
+ * Assumption: The mutex of the returned element is released
+ */
 func (device *Device) NewOutboundElement() *QueueOutboundElement {
-	elem := new(QueueOutboundElement) // TODO: profile, consider sync.Pool
+	// TODO: profile, consider sync.Pool
+	elem := new(QueueOutboundElement)
 	return elem
 }
 
@@ -160,9 +164,8 @@ func (peer *Peer) RoutineNonce() {
 	var elem *QueueOutboundElement
 
 	device := peer.device
-	logger := device.log.Debug
-
-	logger.Println("Routine, nonce worker, started for peer", peer.id)
+	logDebug := device.log.Debug
+	logDebug.Println("Routine, nonce worker, started for peer", peer.id)
 
 	func() {
 
@@ -193,18 +196,18 @@ func (peer *Peer) RoutineNonce() {
 						break
 					}
 				}
-				logger.Println("Key pair:", keyPair)
+				logDebug.Println("Key pair:", keyPair)
 
 				sendSignal(peer.signal.handshakeBegin)
-				logger.Println("Waiting for key-pair, peer", peer.id)
+				logDebug.Println("Waiting for key-pair, peer", peer.id)
 
 				select {
 				case <-peer.signal.newKeyPair:
-					logger.Println("Key-pair negotiated for peer", peer.id)
+					logDebug.Println("Key-pair negotiated for peer", peer.id)
 					goto NextPacket
 
 				case <-peer.signal.flushNonceQueue:
-					logger.Println("Clearing queue for peer", peer.id)
+					logDebug.Println("Clearing queue for peer", peer.id)
 					peer.FlushNonceQueue()
 					elem = nil
 					goto NextPacket
@@ -233,8 +236,6 @@ func (peer *Peer) RoutineNonce() {
 			}
 		}
 	}()
-
-	logger.Println("Routine, nonce worker, stopped for peer", peer.id)
 }
 
 /* Encrypts the elements in the queue
@@ -265,20 +266,16 @@ func (device *Device) RoutineEncryption() {
 
 		// encrypt content
 
-		func() {
-			binary.LittleEndian.PutUint64(nonce[4:], work.nonce)
-			work.packet = work.keyPair.send.Seal(
-				work.packet[:0],
-				nonce[:],
-				work.packet,
-				nil,
-			)
-			work.mutex.Unlock()
-		}()
-
-		// reslice to include header
-
-		work.packet = work.data[:MessageTransportHeaderSize+len(work.packet)]
+		binary.LittleEndian.PutUint64(nonce[4:], work.nonce)
+		work.packet = work.keyPair.send.Seal(
+			work.packet[:0],
+			nonce[:],
+			work.packet,
+			nil,
+		)
+		length := MessageTransportHeaderSize + len(work.packet)
+		work.packet = work.data[:length]
+		work.mutex.Unlock()
 
 		// refresh key if necessary
 
@@ -292,15 +289,15 @@ func (device *Device) RoutineEncryption() {
  * The routine terminates then the outbound queue is closed.
  */
 func (peer *Peer) RoutineSequentialSender() {
-	logger := peer.device.log.Debug
-	logger.Println("Routine, sequential sender, started for peer", peer.id)
+	logDebug := peer.device.log.Debug
+	logDebug.Println("Routine, sequential sender, started for peer", peer.id)
 
 	device := peer.device
 
 	for {
 		select {
 		case <-peer.signal.stop:
-			logger.Println("Routine, sequential sender, stopped for peer", peer.id)
+			logDebug.Println("Routine, sequential sender, stopped for peer", peer.id)
 			return
 		case work := <-peer.queue.outbound:
 			if work.IsDropped() {
@@ -316,7 +313,7 @@ func (peer *Peer) RoutineSequentialSender() {
 				defer peer.mutex.RUnlock()
 
 				if peer.endpoint == nil {
-					logger.Println("No endpoint for peer:", peer.id)
+					logDebug.Println("No endpoint for peer:", peer.id)
 					return
 				}
 
@@ -324,7 +321,7 @@ func (peer *Peer) RoutineSequentialSender() {
 				defer device.net.mutex.RUnlock()
 
 				if device.net.conn == nil {
-					logger.Println("No source for device")
+					logDebug.Println("No source for device")
 					return
 				}
 
diff --git a/src/tun_linux.go b/src/tun_linux.go
index a0bff81..d16a966 100644
--- a/src/tun_linux.go
+++ b/src/tun_linux.go
@@ -74,6 +74,6 @@ func CreateTUN(name string) (TUNDevice, error) {
 	return &NativeTun{
 		fd:   fd,
 		name: newName,
-		mtu:  1500, // TODO: FIX
+		mtu:  0,
 	}, nil
 }