First set of code review patches

15 files changed, 313 insertions, 180 deletions

diff --git a/src/config.go b/src/config.go
index 72a604f..e2d7f20 100644
--- a/src/config.go
+++ b/src/config.go
@@ -61,6 +61,7 @@ func ipcGetOperation(device *Device, socket *bufio.ReadWriter) *IPCError {
 			send(fmt.Sprintf("persistent_keepalive_interval=%d",
 				atomic.LoadUint64(&peer.persistentKeepaliveInterval),
 			))
+
 			for _, ip := range device.routingTable.AllowedIPs(peer) {
 				send("allowed_ip=" + ip.String())
 			}
@@ -89,6 +90,9 @@ func ipcSetOperation(device *Device, socket *bufio.ReadWriter) *IPCError {
 	logDebug := device.log.Debug
 
 	var peer *Peer
+
+	deviceConfig := true
+
 	for scanner.Scan() {
 
 		// parse line
@@ -99,86 +103,110 @@ func ipcSetOperation(device *Device, socket *bufio.ReadWriter) *IPCError {
 		}
 		parts := strings.Split(line, "=")
 		if len(parts) != 2 {
-			return &IPCError{Code: ipcErrorNoKeyValue}
+			return &IPCError{Code: ipcErrorProtocol}
 		}
 		key := parts[0]
 		value := parts[1]
 
-		switch key {
+		/* device configuration */
 
-		/* interface configuration */
+		if deviceConfig {
 
-		case "private_key":
-			var sk NoisePrivateKey
-			if value == "" {
-				device.SetPrivateKey(sk)
-			} else {
-				err := sk.FromHex(value)
-				if err != nil {
-					logError.Println("Failed to set private_key:", err)
-					return &IPCError{Code: ipcErrorInvalidValue}
+			switch key {
+			case "private_key":
+				var sk NoisePrivateKey
+				if value == "" {
+					device.SetPrivateKey(sk)
+				} else {
+					err := sk.FromHex(value)
+					if err != nil {
+						logError.Println("Failed to set private_key:", err)
+						return &IPCError{Code: ipcErrorInvalid}
+					}
+					device.SetPrivateKey(sk)
 				}
-				device.SetPrivateKey(sk)
-			}
 
-		case "listen_port":
-			port, err := strconv.ParseUint(value, 10, 16)
-			if err != nil {
-				logError.Println("Failed to set listen_port:", err)
-				return &IPCError{Code: ipcErrorInvalidValue}
-			}
-			netc := &device.net
-			netc.mutex.Lock()
-			if netc.addr.Port != int(port) {
-				if netc.conn != nil {
-					netc.conn.Close()
+			case "listen_port":
+				port, err := strconv.ParseUint(value, 10, 16)
+				if err != nil {
+					logError.Println("Failed to set listen_port:", err)
+					return &IPCError{Code: ipcErrorInvalid}
 				}
-				netc.addr.Port = int(port)
-				netc.conn, err = net.ListenUDP("udp", netc.addr)
-			}
-			netc.mutex.Unlock()
-			if err != nil {
-				logError.Println("Failed to create UDP listener:", err)
-				return &IPCError{Code: ipcErrorInvalidValue}
-			}
+				netc := &device.net
+				netc.mutex.Lock()
+				if netc.addr.Port != int(port) {
+					if netc.conn != nil {
+						netc.conn.Close()
+					}
+					netc.addr.Port = int(port)
+					netc.conn, err = net.ListenUDP("udp", netc.addr)
+				}
+				netc.mutex.Unlock()
+				if err != nil {
+					logError.Println("Failed to create UDP listener:", err)
+					return &IPCError{Code: ipcErrorIO}
+				}
+				// TODO: Clear source address of all peers
 
-		case "fwmark":
-			logError.Println("FWMark not handled yet")
+			case "fwmark":
+				logError.Println("FWMark not handled yet")
+				// TODO: Clear source address of all peers
 
-		case "public_key":
-			var pubKey NoisePublicKey
-			err := pubKey.FromHex(value)
-			if err != nil {
-				logError.Println("Failed to get peer by public_key:", err)
-				return &IPCError{Code: ipcErrorInvalidValue}
-			}
-			device.mutex.RLock()
-			peer, _ = device.peers[pubKey]
-			device.mutex.RUnlock()
-			if peer == nil {
-				peer = device.NewPeer(pubKey)
-			}
+			case "public_key":
 
-		case "replace_peers":
-			if value == "true" {
-				device.RemoveAllPeers()
-			} else {
-				logError.Println("Failed to set replace_peers, invalid value:", value)
-				return &IPCError{Code: ipcErrorInvalidValue}
-			}
+				// switch to peer configuration
 
-		default:
+				deviceConfig = false
 
-			/* peer configuration */
+			case "replace_peers":
+				if value != "true" {
+					logError.Println("Failed to set replace_peers, invalid value:", value)
+					return &IPCError{Code: ipcErrorInvalid}
+				}
+				device.RemoveAllPeers()
 
-			if peer == nil {
-				logError.Println("No peer referenced, before peer operation")
-				return &IPCError{Code: ipcErrorNoPeer}
+			default:
+				logError.Println("Invalid UAPI key (device configuration):", key)
+				return &IPCError{Code: ipcErrorInvalid}
 			}
+		}
+
+		/* peer configuration */
+
+		if !deviceConfig {
 
 			switch key {
 
+			case "public_key":
+				var pubKey NoisePublicKey
+				err := pubKey.FromHex(value)
+				if err != nil {
+					logError.Println("Failed to get peer by public_key:", err)
+					return &IPCError{Code: ipcErrorInvalid}
+				}
+
+				// check if public key of peer equal to device
+
+				device.mutex.RLock()
+				if device.publicKey.Equals(pubKey) {
+					device.mutex.RUnlock()
+					logError.Println("Public key of peer matches private key of device")
+					return &IPCError{Code: ipcErrorInvalid}
+				}
+
+				// find peer referenced
+
+				peer, _ = device.peers[pubKey]
+				device.mutex.RUnlock()
+				if peer == nil {
+					peer = device.NewPeer(pubKey)
+				}
+
 			case "remove":
+				if value != "true" {
+					logError.Println("Failed to set remove, invalid value:", value)
+					return &IPCError{Code: ipcErrorInvalid}
+				}
 				device.RemovePeer(peer.handshake.remoteStatic)
 				logDebug.Println("Removing", peer.String())
 				peer = nil
@@ -191,50 +219,67 @@ func ipcSetOperation(device *Device, socket *bufio.ReadWriter) *IPCError {
 				}()
 				if err != nil {
 					logError.Println("Failed to set preshared_key:", err)
-					return &IPCError{Code: ipcErrorInvalidValue}
+					return &IPCError{Code: ipcErrorInvalid}
 				}
 
 			case "endpoint":
+				// TODO: Only IP and port
 				addr, err := net.ResolveUDPAddr("udp", value)
 				if err != nil {
 					logError.Println("Failed to set endpoint:", value)
-					return &IPCError{Code: ipcErrorInvalidValue}
+					return &IPCError{Code: ipcErrorInvalid}
 				}
 				peer.mutex.Lock()
 				peer.endpoint = addr
 				peer.mutex.Unlock()
 
 			case "persistent_keepalive_interval":
-				secs, err := strconv.ParseInt(value, 10, 64)
-				if secs < 0 || err != nil {
+
+				// update keep-alive interval
+
+				secs, err := strconv.ParseUint(value, 10, 16)
+				if err != nil {
 					logError.Println("Failed to set persistent_keepalive_interval:", err)
-					return &IPCError{Code: ipcErrorInvalidValue}
+					return &IPCError{Code: ipcErrorInvalid}
 				}
-				atomic.StoreUint64(
+
+				old := atomic.SwapUint64(
 					&peer.persistentKeepaliveInterval,
-					uint64(secs),
+					secs,
 				)
 
+				// send immediate keep-alive
+
+				if old == 0 && secs != 0 {
+					up, err := device.tun.IsUp()
+					if err != nil {
+						logError.Println("Failed to get tun device status:", err)
+						return &IPCError{Code: ipcErrorIO}
+					}
+					if up {
+						peer.SendKeepAlive()
+					}
+				}
+
 			case "replace_allowed_ips":
-				if value == "true" {
-					device.routingTable.RemovePeer(peer)
-				} else {
+				if value != "true" {
 					logError.Println("Failed to set replace_allowed_ips, invalid value:", value)
-					return &IPCError{Code: ipcErrorInvalidValue}
+					return &IPCError{Code: ipcErrorInvalid}
 				}
+				device.routingTable.RemovePeer(peer)
 
 			case "allowed_ip":
 				_, network, err := net.ParseCIDR(value)
 				if err != nil {
 					logError.Println("Failed to set allowed_ip:", err)
-					return &IPCError{Code: ipcErrorInvalidValue}
+					return &IPCError{Code: ipcErrorInvalid}
 				}
 				ones, _ := network.Mask.Size()
 				device.routingTable.Insert(network.IP, uint(ones), peer)
 
 			default:
-				logError.Println("Invalid UAPI key:", key)
-				return &IPCError{Code: ipcErrorInvalidKey}
+				logError.Println("Invalid UAPI key (peer configuration):", key)
+				return &IPCError{Code: ipcErrorInvalid}
 			}
 		}
 	}
@@ -244,6 +289,8 @@ func ipcSetOperation(device *Device, socket *bufio.ReadWriter) *IPCError {
 
 func ipcHandle(device *Device, socket net.Conn) {
 
+	// create buffered read/writer
+
 	defer socket.Close()
 
 	buffered := func(s io.ReadWriter) *bufio.ReadWriter {
@@ -259,30 +306,30 @@ func ipcHandle(device *Device, socket net.Conn) {
 		return
 	}
 
-	switch op {
+	// handle operation
 
+	var status *IPCError
+
+	switch op {
 	case "set=1\n":
 		device.log.Debug.Println("Config, set operation")
-		err := ipcSetOperation(device, buffered)
-		if err != nil {
-			fmt.Fprintf(buffered, "errno=%d\n\n", err.ErrorCode())
-		} else {
-			fmt.Fprintf(buffered, "errno=0\n\n")
-		}
-		return
+		status = ipcSetOperation(device, buffered)
 
 	case "get=1\n":
 		device.log.Debug.Println("Config, get operation")
-		err := ipcGetOperation(device, buffered)
-		if err != nil {
-			fmt.Fprintf(buffered, "errno=%d\n\n", err.ErrorCode())
-		} else {
-			fmt.Fprintf(buffered, "errno=0\n\n")
-		}
-		return
+		status = ipcGetOperation(device, buffered)
 
 	default:
 		device.log.Error.Println("Invalid UAPI operation:", op)
+		return
+	}
+
+	// write status
 
+	if status != nil {
+		device.log.Error.Println(status)
+		fmt.Fprintf(buffered, "errno=%d\n\n", status.ErrorCode())
+	} else {
+		fmt.Fprintf(buffered, "errno=0\n\n")
 	}
 }
diff --git a/src/constants.go b/src/constants.go
index 09d33d8..f09ded6 100644
--- a/src/constants.go
+++ b/src/constants.go
@@ -16,6 +16,7 @@ const (
 	KeepaliveTimeout        = time.Second * 10
 	CookieRefreshTime       = time.Second * 120
 	MaxHandshakeAttemptTime = time.Second * 90
+	PaddingMultiple         = 16
 )
 
 const (
@@ -31,5 +32,5 @@ const (
 	QueueHandshakeSize     = 1024
 	QueueHandshakeBusySize = QueueHandshakeSize / 8
 	MinMessageSize         = MessageTransportSize // size of keep-alive
-	MaxMessageSize         = (1 << 16) - 1
+	MaxMessageSize         = ((1 << 16) - 1) + MessageTransportHeaderSize
 )
diff --git a/src/device.go b/src/device.go
index 1185d60..de96f0b 100644
--- a/src/device.go
+++ b/src/device.go
@@ -1,6 +1,8 @@
 package main
 
 import (
+	"errors"
+	"fmt"
 	"net"
 	"runtime"
 	"sync"
@@ -10,6 +12,7 @@ import (
 
 type Device struct {
 	mtu       int32
+	tun       TUNDevice
 	log       *Logger // collection of loggers for levels
 	idCounter uint    // for assigning debug ids to peers
 	fwMark    uint32
@@ -43,24 +46,46 @@ type Device struct {
 	mac         MACStateDevice
 }
 
-func (device *Device) SetPrivateKey(sk NoisePrivateKey) {
+func (device *Device) SetPrivateKey(sk NoisePrivateKey) error {
 	device.mutex.Lock()
 	defer device.mutex.Unlock()
 
+	// check if public key is matching any peer
+
+	publicKey := sk.publicKey()
+	for _, peer := range device.peers {
+		h := &peer.handshake
+		h.mutex.RLock()
+		if h.remoteStatic.Equals(publicKey) {
+			h.mutex.RUnlock()
+			return errors.New("Private key matches public key of peer")
+		}
+		h.mutex.RUnlock()
+	}
+
 	// update key material
 
 	device.privateKey = sk
-	device.publicKey = sk.publicKey()
-	device.mac.Init(device.publicKey)
+	device.publicKey = publicKey
+	device.mac.Init(publicKey)
 
 	// do DH precomputations
 
+	isZero := device.privateKey.IsZero()
+
 	for _, peer := range device.peers {
 		h := &peer.handshake
 		h.mutex.Lock()
-		h.precomputedStaticStatic = device.privateKey.sharedSecret(h.remoteStatic)
+		if isZero {
+			h.precomputedStaticStatic = [NoisePublicKeySize]byte{}
+		} else {
+			h.precomputedStaticStatic = device.privateKey.sharedSecret(h.remoteStatic)
+		}
+		fmt.Println(h.precomputedStaticStatic)
 		h.mutex.Unlock()
 	}
+
+	return nil
 }
 
 func (device *Device) GetMessageBuffer() *[MaxMessageSize]byte {
@@ -77,6 +102,7 @@ func NewDevice(tun TUNDevice, logLevel int) *Device {
 	device.mutex.Lock()
 	defer device.mutex.Unlock()
 
+	device.tun = tun
 	device.log = NewLogger(logLevel)
 	device.peers = make(map[NoisePublicKey]*Peer)
 	device.indices.Init()
@@ -119,22 +145,22 @@ func NewDevice(tun TUNDevice, logLevel int) *Device {
 	}
 
 	go device.RoutineBusyMonitor()
-	go device.RoutineMTUUpdater(tun)
-	go device.RoutineWriteToTUN(tun)
-	go device.RoutineReadFromTUN(tun)
+	go device.RoutineMTUUpdater()
+	go device.RoutineWriteToTUN()
+	go device.RoutineReadFromTUN()
 	go device.RoutineReceiveIncomming()
 	go device.ratelimiter.RoutineGarbageCollector(device.signal.stop)
 
 	return device
 }
 
-func (device *Device) RoutineMTUUpdater(tun TUNDevice) {
+func (device *Device) RoutineMTUUpdater() {
 	logError := device.log.Error
 	for ; ; time.Sleep(5 * time.Second) {
 
 		// load updated MTU
 
-		mtu, err := tun.MTU()
+		mtu, err := device.tun.MTU()
 		if err != nil {
 			logError.Println("Failed to load updated MTU of device:", err)
 			continue
diff --git a/src/index.go b/src/index.go
index 44b4974..e518b0f 100644
--- a/src/index.go
+++ b/src/index.go
@@ -3,6 +3,7 @@ package main
 import (
 	"crypto/rand"
 	"sync"
+	"unsafe"
 )
 
 /* Index=0 is reserved for unset indecies
@@ -23,14 +24,7 @@ type IndexTable struct {
 func randUint32() (uint32, error) {
 	var buff [4]byte
 	_, err := rand.Read(buff[:])
-	id := uint32(buff[0])
-	id <<= 8
-	id |= uint32(buff[1])
-	id <<= 8
-	id |= uint32(buff[2])
-	id <<= 8
-	id |= uint32(buff[3])
-	return id, err
+	return *((*uint32)(unsafe.Pointer(&buff))), err
 }
 
 func (table *IndexTable) Init() {
diff --git a/src/macs.go b/src/macs.go
index 841ef31..beb5f76 100644
--- a/src/macs.go
+++ b/src/macs.go
@@ -3,7 +3,6 @@ package main
 import (
 	"crypto/hmac"
 	"crypto/rand"
-	"errors"
 	"golang.org/x/crypto/blake2s"
 	"net"
 	"sync"
@@ -15,14 +14,14 @@ type MACStateDevice struct {
 	refreshed time.Time
 	secret    [blake2s.Size]byte
 	keyMAC1   [blake2s.Size]byte
-	keyMAC2   [blake2s.Size]byte
+	keyMAC2   [blake2s.Size]byte // TODO: Change to more descriptive size constant, rename to something.
 }
 
 type MACStatePeer struct {
 	mutex     sync.RWMutex
 	cookieSet time.Time
 	cookie    [blake2s.Size128]byte
-	lastMAC1  [blake2s.Size128]byte
+	lastMAC1  [blake2s.Size128]byte // TODO: Check if set
 	keyMAC1   [blake2s.Size]byte
 	keyMAC2   [blake2s.Size]byte
 }
@@ -83,7 +82,7 @@ func (state *MACStateDevice) CheckMAC2(msg []byte, addr *net.UDPAddr) bool {
 		port := [2]byte{byte(addr.Port >> 8), byte(addr.Port)}
 		mac, _ := blake2s.New128(state.secret[:])
 		mac.Write(addr.IP)
-		mac.Write(port[:])
+		mac.Write(port[:]) // TODO: Be faster and more platform dependent?
 		mac.Sum(cookie[:0])
 	}()
 
@@ -130,7 +129,7 @@ func (device *Device) CreateMessageCookieReply(
 		port := [2]byte{byte(addr.Port >> 8), byte(addr.Port)}
 		mac, _ := blake2s.New128(state.secret[:])
 		mac.Write(addr.IP)
-		mac.Write(port[:])
+		mac.Write(port[:]) // TODO: Do whatever we did above
 		mac.Sum(cookie[:0])
 	}()
 
@@ -196,6 +195,7 @@ func (device *Device) ConsumeMessageCookieReply(msg *MessageCookieReply) bool {
 	if err != nil {
 		return false
 	}
+
 	state.cookieSet = time.Now()
 	state.cookie = cookie
 	return true
@@ -229,10 +229,6 @@ func (state *MACStatePeer) Init(pk NoisePublicKey) {
 func (state *MACStatePeer) AddMacs(msg []byte) {
 	size := len(msg)
 
-	if size < blake2s.Size128*2 {
-		panic(errors.New("bug: message too short"))
-	}
-
 	startMac1 := size - (blake2s.Size128 * 2)
 	startMac2 := size - blake2s.Size128
 
@@ -250,6 +246,7 @@ func (state *MACStatePeer) AddMacs(msg []byte) {
 		mac.Sum(mac1[:0])
 	}()
 	copy(state.lastMAC1[:], mac1)
+	// TODO: Set lastMac flag
 
 	// set mac2
 
diff --git a/src/noise_helpers.go b/src/noise_helpers.go
index 1e622a5..105f78f 100644
--- a/src/noise_helpers.go
+++ b/src/noise_helpers.go
@@ -47,6 +47,14 @@ func KDF3(key []byte, input []byte) (t0 [blake2s.Size]byte, t1 [blake2s.Size]byt
 	return
 }
 
+func isZero(val []byte) bool {
+	var acc byte
+	for _, b := range val {
+		acc |= b
+	}
+	return acc == 0
+}
+
 /* curve25519 wrappers */
 
 func newPrivateKey() (sk NoisePrivateKey, err error) {
diff --git a/src/noise_protocol.go b/src/noise_protocol.go
index e2ff573..5c776a8 100644
--- a/src/noise_protocol.go
+++ b/src/noise_protocol.go
@@ -135,6 +135,10 @@ func (device *Device) CreateMessageInitiation(peer *Peer) (*MessageInitiation, e
 	handshake.mutex.Lock()
 	defer handshake.mutex.Unlock()
 
+	if isZero(handshake.precomputedStaticStatic[:]) {
+		return nil, errors.New("Static shared secret is zero")
+	}
+
 	// create ephemeral key
 
 	var err error
@@ -226,7 +230,11 @@ func (device *Device) ConsumeMessageInitiation(msg *MessageInitiation) *Peer {
 	if peer == nil {
 		return nil
 	}
+
 	handshake := &peer.handshake
+	if isZero(handshake.precomputedStaticStatic[:]) {
+		return nil
+	}
 
 	// verify identity
 
@@ -472,6 +480,7 @@ func (peer *Peer) NewKeyPair() *KeyPair {
 	func() {
 		kp.mutex.Lock()
 		defer kp.mutex.Unlock()
+		// TODO: Adapt kernel behavior noise.c:161
 		if isInitiator {
 			if kp.previous != nil {
 				kp.previous.send = nil
diff --git a/src/noise_types.go b/src/noise_types.go
index 5ebc130..1a944df 100644
--- a/src/noise_types.go
+++ b/src/noise_types.go
@@ -1,6 +1,7 @@
 package main
 
 import (
+	"crypto/subtle"
 	"encoding/hex"
 	"errors"
 	"golang.org/x/crypto/chacha20poly1305"
@@ -31,12 +32,12 @@ func loadExactHex(dst []byte, src string) error {
 }
 
 func (key NoisePrivateKey) IsZero() bool {
-	for _, b := range key[:] {
-		if b != 0 {
-			return false
-		}
-	}
-	return true
+	var zero NoisePrivateKey
+	return key.Equals(zero)
+}
+
+func (key NoisePrivateKey) Equals(tar NoisePrivateKey) bool {
+	return subtle.ConstantTimeCompare(key[:], tar[:]) == 1
 }
 
 func (key *NoisePrivateKey) FromHex(src string) error {
@@ -55,6 +56,15 @@ func (key NoisePublicKey) ToHex() string {
 	return hex.EncodeToString(key[:])
 }
 
+func (key NoisePublicKey) IsZero() bool {
+	var zero NoisePublicKey
+	return key.Equals(zero)
+}
+
+func (key NoisePublicKey) Equals(tar NoisePublicKey) bool {
+	return subtle.ConstantTimeCompare(key[:], tar[:]) == 1
+}
+
 func (key *NoiseSymmetricKey) FromHex(src string) error {
 	return loadExactHex(key[:], src)
 }
diff --git a/src/receive.go b/src/receive.go
index 700b894..fb5c51f 100644
--- a/src/receive.go
+++ b/src/receive.go
@@ -73,6 +73,8 @@ func (device *Device) addToHandshakeQueue(
 }
 
 /* Routine determining the busy state of the interface
+ *
+ * TODO: Under load for some time
  */
 func (device *Device) RoutineBusyMonitor() {
 	samples := 0
@@ -131,6 +133,7 @@ func (device *Device) RoutineReceiveIncomming() {
 			buffer = device.GetMessageBuffer()
 		}
 
+		// TODO: Take writelock to sleep
 		device.net.mutex.RLock()
 		conn := device.net.conn
 		device.net.mutex.RUnlock()
@@ -139,6 +142,7 @@ func (device *Device) RoutineReceiveIncomming() {
 			continue
 		}
 
+		// TODO: Wait for new conn or message
 		conn.SetReadDeadline(time.Now().Add(time.Second))
 
 		size, raddr, err := conn.ReadFromUDP(buffer[:])
@@ -156,6 +160,8 @@ func (device *Device) RoutineReceiveIncomming() {
 
 			case MessageInitiationType, MessageResponseType:
 
+				// TODO: Check size early
+
 				// add to handshake queue
 
 				device.addToHandshakeQueue(
@@ -171,6 +177,8 @@ func (device *Device) RoutineReceiveIncomming() {
 
 			case MessageCookieReplyType:
 
+				// TODO: Queue all the things
+
 				// verify and update peer cookie state
 
 				if len(packet) != MessageCookieReplySize {
@@ -250,7 +258,7 @@ func (device *Device) RoutineDecryption() {
 		// check if dropped
 
 		if elem.IsDropped() {
-			elem.mutex.Unlock()
+			elem.mutex.Unlock() // TODO: Make consistent with send
 			continue
 		}
 
@@ -318,6 +326,7 @@ func (device *Device) RoutineHandshake() {
 					logError.Println("Failed to create cookie reply:", err)
 					return
 				}
+				// TODO: Use temp
 				writer := bytes.NewBuffer(elem.packet[:0])
 				binary.Write(writer, binary.LittleEndian, reply)
 				elem.packet = writer.Bytes()
@@ -330,6 +339,8 @@ func (device *Device) RoutineHandshake() {
 
 			// ratelimit
 
+			// TODO: Only ratelimit when busy
+
 			if !device.ratelimiter.Allow(elem.source.IP) {
 				return
 			}
@@ -364,9 +375,14 @@ func (device *Device) RoutineHandshake() {
 					)
 					return
 				}
-				peer.TimerPacketReceived()
+
+				// update timers
+
+				peer.TimerAnyAuthenticatedPacketTraversal()
+				peer.TimerAnyAuthenticatedPacketReceived()
 
 				// update endpoint
+				// TODO: Add a race condition \s
 
 				peer.mutex.Lock()
 				peer.endpoint = elem.source
@@ -381,6 +397,7 @@ func (device *Device) RoutineHandshake() {
 				}
 
 				peer.TimerEphemeralKeyCreated()
+				peer.NewKeyPair()
 
 				logDebug.Println("Creating response message for", peer.String())
 
@@ -392,8 +409,7 @@ func (device *Device) RoutineHandshake() {
 				// send response
 
 				peer.SendBuffer(packet)
-				peer.TimerPacketSent()
-				peer.NewKeyPair()
+				peer.TimerAnyAuthenticatedPacketTraversal()
 
 			case MessageResponseType:
 
@@ -423,8 +439,14 @@ func (device *Device) RoutineHandshake() {
 					return
 				}
 
-				peer.TimerPacketReceived()
+				// update timers
+
+				peer.TimerAnyAuthenticatedPacketTraversal()
+				peer.TimerAnyAuthenticatedPacketReceived()
 				peer.TimerHandshakeComplete()
+
+				// derive key-pair
+
 				peer.NewKeyPair()
 				peer.SendKeepAlive()
 
@@ -467,8 +489,8 @@ func (peer *Peer) RoutineSequentialReceiver() {
 				return
 			}
 
-			peer.TimerPacketReceived()
-			peer.TimerTransportReceived()
+			peer.TimerAnyAuthenticatedPacketTraversal()
+			peer.TimerAnyAuthenticatedPacketReceived()
 			peer.KeepKeyFreshReceiving()
 
 			// check if using new key-pair
@@ -504,6 +526,7 @@ func (peer *Peer) RoutineSequentialReceiver() {
 
 				field := elem.packet[IPv4offsetTotalLength : IPv4offsetTotalLength+2]
 				length := binary.BigEndian.Uint16(field)
+				// TODO: check length of packet & NOT TOO SMALL either
 				elem.packet = elem.packet[:length]
 
 				// verify IPv4 source
@@ -525,6 +548,7 @@ func (peer *Peer) RoutineSequentialReceiver() {
 				field := elem.packet[IPv6offsetPayloadLength : IPv6offsetPayloadLength+2]
 				length := binary.BigEndian.Uint16(field)
 				length += ipv6.HeaderLen
+				// TODO: check length of packet
 				elem.packet = elem.packet[:length]
 
 				// verify IPv6 source
@@ -542,11 +566,13 @@ func (peer *Peer) RoutineSequentialReceiver() {
 
 			atomic.AddUint64(&peer.stats.rxBytes, uint64(len(elem.packet)))
 			device.addToInboundQueue(device.queue.inbound, elem)
+
+			// TODO: move TUN write into per peer routine
 		}()
 	}
 }
 
-func (device *Device) RoutineWriteToTUN(tun TUNDevice) {
+func (device *Device) RoutineWriteToTUN() {
 
 	logError := device.log.Error
 	logDebug := device.log.Debug
@@ -557,7 +583,7 @@ func (device *Device) RoutineWriteToTUN(tun TUNDevice) {
 		case <-device.signal.stop:
 			return
 		case elem := <-device.queue.inbound:
-			_, err := tun.Write(elem.packet)
+			_, err := device.tun.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 37078b9..fc35732 100644
--- a/src/send.go
+++ b/src/send.go
@@ -110,17 +110,19 @@ func addToEncryptionQueue(
 }
 
 func (peer *Peer) SendBuffer(buffer []byte) (int, error) {
+	peer.device.net.mutex.RLock()
+	defer peer.device.net.mutex.RUnlock()
 
 	peer.mutex.RLock()
+	defer peer.mutex.RUnlock()
+
 	endpoint := peer.endpoint
-	peer.mutex.RUnlock()
+	conn := peer.device.net.conn
+
 	if endpoint == nil {
 		return 0, ErrorNoEndpoint
 	}
 
-	peer.device.net.mutex.RLock()
-	conn := peer.device.net.conn
-	peer.device.net.mutex.RUnlock()
 	if conn == nil {
 		return 0, ErrorNoConnection
 	}
@@ -133,13 +135,13 @@ func (peer *Peer) SendBuffer(buffer []byte) (int, error) {
  *
  * Obs. Single instance per TUN device
  */
-func (device *Device) RoutineReadFromTUN(tun TUNDevice) {
+func (device *Device) RoutineReadFromTUN() {
 
-	if tun == nil {
+	if device.tun == nil {
 		return
 	}
 
-	elem := device.NewOutboundElement()
+	var elem *QueueOutboundElement
 
 	logDebug := device.log.Debug
 	logError := device.log.Error
@@ -153,32 +155,38 @@ func (device *Device) RoutineReadFromTUN(tun TUNDevice) {
 			elem = device.NewOutboundElement()
 		}
 
+		// TODO: THIS!
 		elem.packet = elem.buffer[MessageTransportHeaderSize:]
-		size, err := tun.Read(elem.packet)
+		size, err := device.tun.Read(elem.packet)
 		if err != nil {
-
-			// stop process
-
 			logError.Println("Failed to read packet from TUN device:", err)
 			device.Close()
 			return
 		}
 
-		elem.packet = elem.packet[:size]
-		if len(elem.packet) < ipv4.HeaderLen {
-			logError.Println("Packet too short, length:", size)
+		if size == 0 {
 			continue
 		}
 
+		println(size, err)
+
+		elem.packet = elem.packet[:size]
+
 		// lookup peer
 
 		var peer *Peer
 		switch elem.packet[0] >> 4 {
 		case ipv4.Version:
+			if len(elem.packet) < ipv4.HeaderLen {
+				continue
+			}
 			dst := elem.packet[IPv4offsetDst : IPv4offsetDst+net.IPv4len]
 			peer = device.routingTable.LookupIPv4(dst)
 
 		case ipv6.Version:
+			if len(elem.packet) < ipv6.HeaderLen {
+				continue
+			}
 			dst := elem.packet[IPv6offsetDst : IPv6offsetDst+net.IPv6len]
 			peer = device.routingTable.LookupIPv6(dst)
 
@@ -190,10 +198,15 @@ func (device *Device) RoutineReadFromTUN(tun TUNDevice) {
 			continue
 		}
 
+		// check if known endpoint
+
+		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
 
@@ -334,8 +347,12 @@ func (device *Device) RoutineEncryption() {
 		// pad content to MTU size
 
 		mtu := int(atomic.LoadInt32(&device.mtu))
-		for i := len(elem.packet); i < mtu; i++ {
-			elem.packet = append(elem.packet, 0)
+		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)
+			}
+			// TODO: How good is this code
 		}
 
 		// encrypt content (append to header)
@@ -390,7 +407,7 @@ func (peer *Peer) RoutineSequentialSender() {
 
 			// update timers
 
-			peer.TimerPacketSent()
+			peer.TimerAnyAuthenticatedPacketTraversal()
 			if len(elem.packet) != MessageKeepaliveSize {
 				peer.TimerDataSent()
 			}
diff --git a/src/timers.go b/src/timers.go
index 5a16e9b..1be85f0 100644
--- a/src/timers.go
+++ b/src/timers.go
@@ -60,10 +60,8 @@ func (peer *Peer) SendKeepAlive() bool {
 	return true
 }
 
-/* Authenticated data packet send
- * Always called together with peer.EventPacketSend
- *
- * - Start new handshake timer
+/* Event:
+ * Sent non-empty (authenticated) transport message
  */
 func (peer *Peer) TimerDataSent() {
 	timerStop(peer.timer.keepalivePassive)
@@ -75,8 +73,6 @@ func (peer *Peer) TimerDataSent() {
 
 /* Event:
  * Received non-empty (authenticated) transport message
- *
- * - Start passive keep-alive timer
  */
 func (peer *Peer) TimerDataReceived() {
 	if peer.timer.pendingKeepalivePassive {
@@ -88,17 +84,16 @@ func (peer *Peer) TimerDataReceived() {
 }
 
 /* Event:
- * Any (authenticated) transport message received
- * (keep-alive or data)
+ * Any (authenticated) packet received
  */
-func (peer *Peer) TimerTransportReceived() {
+func (peer *Peer) TimerAnyAuthenticatedPacketReceived() {
 	timerStop(peer.timer.newHandshake)
 }
 
 /* Event:
- * Any packet send to the peer.
+ * Any authenticated packet send / received.
  */
-func (peer *Peer) TimerPacketSent() {
+func (peer *Peer) TimerAnyAuthenticatedPacketTraversal() {
 	interval := atomic.LoadUint64(&peer.persistentKeepaliveInterval)
 	if interval > 0 {
 		duration := time.Duration(interval) * time.Second
@@ -106,13 +101,6 @@ func (peer *Peer) TimerPacketSent() {
 	}
 }
 
-/* Event:
- * Any authenticated packet received from peer
- */
-func (peer *Peer) TimerPacketReceived() {
-	peer.TimerPacketSent()
-}
-
 /* Called after succesfully completing a handshake.
  * i.e. after:
  *
@@ -129,7 +117,9 @@ func (peer *Peer) TimerHandshakeComplete() {
 	peer.device.log.Info.Println("Negotiated new handshake for", peer.String())
 }
 
-/* Called whenever an ephemeral key is generated
+/* Event:
+ * An ephemeral key is generated
+ *
  * i.e after:
  *
  * CreateMessageInitiation
@@ -257,7 +247,6 @@ func (peer *Peer) RoutineHandshakeInitiator() {
 
 		select {
 		case <-peer.signal.handshakeBegin:
-			signalSend(peer.signal.handshakeBegin)
 		case <-peer.signal.stop:
 			return
 		}
@@ -303,7 +292,6 @@ func (peer *Peer) RoutineHandshakeInitiator() {
 			binary.Write(writer, binary.LittleEndian, msg)
 			packet := writer.Bytes()
 			peer.mac.AddMacs(packet)
-			peer.TimerPacketSent()
 
 			_, err = peer.SendBuffer(packet)
 			if err != nil {
@@ -314,6 +302,8 @@ func (peer *Peer) RoutineHandshakeInitiator() {
 				continue
 			}
 
+			peer.TimerAnyAuthenticatedPacketTraversal()
+
 			// set timeout
 
 			timeout := time.NewTimer(RekeyTimeout)
@@ -337,7 +327,6 @@ func (peer *Peer) RoutineHandshakeInitiator() {
 				continue
 
 			}
-
 		}
 
 		// allow new signal to be set
diff --git a/src/trie.go b/src/trie.go
index e81b5b6..aa96a8a 100644
--- a/src/trie.go
+++ b/src/trie.go
@@ -32,11 +32,14 @@ type Trie struct {
 /* Finds length of matching prefix
  * TODO: Make faster
  *
- * Assumption: len(ip1) == len(ip2)
+ * Assumption:
+ *	  len(ip1) == len(ip2)
+ *	  len(ip1) mod 4 = 0
  */
-func commonBits(ip1 net.IP, ip2 net.IP) uint {
+func commonBits(ip1 []byte, ip2 []byte) uint {
 	var i uint
-	size := uint(len(ip1))
+	size := uint(len(ip1)) / 4
+
 	for i = 0; i < size; i++ {
 		v := ip1[i] ^ ip2[i]
 		if v != 0 {
diff --git a/src/tun.go b/src/tun.go
index f529c54..d782bd5 100644
--- a/src/tun.go
+++ b/src/tun.go
@@ -9,6 +9,7 @@ const DefaultMTU = 1420
 type TUNDevice interface {
 	Read([]byte) (int, error)  // read a packet from the device (without any additional headers)
 	Write([]byte) (int, error) // writes a packet to the device (without any additional headers)
+	IsUp() (bool, error)       // is the interface up?
 	MTU() (int, error)         // returns the MTU of the device
 	Name() string              // returns the current name
 }
diff --git a/src/tun_linux.go b/src/tun_linux.go
index 261d142..d0e2f47 100644
--- a/src/tun_linux.go
+++ b/src/tun_linux.go
@@ -7,6 +7,7 @@ import (
 	"encoding/binary"
 	"errors"
 	"golang.org/x/sys/unix"
+	"net"
 	"os"
 	"strings"
 	"unsafe"
@@ -19,6 +20,11 @@ type NativeTun struct {
 	name string
 }
 
+func (tun *NativeTun) IsUp() (bool, error) {
+	inter, err := net.InterfaceByName(tun.name)
+	return inter.Flags&net.FlagUp != 0, err
+}
+
 func (tun *NativeTun) Name() string {
 	return tun.name
 }
diff --git a/src/uapi_linux.go b/src/uapi_linux.go
index fd83918..d6d78e7 100644
--- a/src/uapi_linux.go
+++ b/src/uapi_linux.go
@@ -11,13 +11,12 @@ import (
 )
 
 const (
-	ipcErrorIO           = int64(unix.EIO)
-	ipcErrorNoPeer       = int64(unix.EPROTO)
-	ipcErrorNoKeyValue   = int64(unix.EPROTO)
-	ipcErrorInvalidKey   = int64(unix.EPROTO)
-	ipcErrorInvalidValue = int64(unix.EPROTO)
-	socketDirectory      = "/var/run/wireguard"
-	socketName           = "%s.sock"
+	ipcErrorIO         = -int64(unix.EIO)
+	ipcErrorNotDefined = -int64(unix.ENODEV)
+	ipcErrorProtocol   = -int64(unix.EPROTO)
+	ipcErrorInvalid    = -int64(unix.EINVAL)
+	socketDirectory    = "/var/run/wireguard"
+	socketName         = "%s.sock"
 )
 
 /* TODO: