device: update transfer counters correctly

The rule is to always update them to the full packet size minus UDP/IP
encapsulation for all authenticated packet types.

device/peer.go

@@ -10,6 +10,7 @@ import (
 	"errors"
 	"fmt"
 	"sync"
+	"sync/atomic"
 	"time"
 )
 
@@ -140,7 +141,11 @@ func (peer *Peer) SendBuffer(buffer []byte) error {
 		return errors.New("no known endpoint for peer")
 	}
 
-	return peer.device.net.bind.Send(buffer, peer.endpoint)
+	err := peer.device.net.bind.Send(buffer, peer.endpoint)
+	if err == nil {
+		atomic.AddUint64(&peer.stats.txBytes, uint64(len(buffer)))
+	}
+	return err
 }
 
 func (peer *Peer) String() string {

device/receive.go

@@ -427,6 +427,7 @@ func (device *Device) RoutineHandshake() {
 			peer.SetEndpointFromPacket(elem.endpoint)
 
 			logDebug.Println(peer, "- Received handshake initiation")
+			atomic.AddUint64(&peer.stats.rxBytes, uint64(len(elem.packet)))
 
 			peer.SendHandshakeResponse()
 
@@ -457,6 +458,7 @@ func (device *Device) RoutineHandshake() {
 			peer.SetEndpointFromPacket(elem.endpoint)
 
 			logDebug.Println(peer, "- Received handshake response")
+			atomic.AddUint64(&peer.stats.rxBytes, uint64(len(elem.packet)))
 
 			// update timers
 
@@ -581,6 +583,7 @@ func (peer *Peer) RoutineSequentialReceiver() {
 		peer.keepKeyFreshReceiving()
 		peer.timersAnyAuthenticatedPacketTraversal()
 		peer.timersAnyAuthenticatedPacketReceived()
+		atomic.AddUint64(&peer.stats.rxBytes, uint64(len(elem.packet)+MinMessageSize))
 
 		// check for keepalive
 
@@ -656,7 +659,6 @@ func (peer *Peer) RoutineSequentialReceiver() {
 		// write to tun device
 
 		offset := MessageTransportOffsetContent
-		atomic.AddUint64(&peer.stats.rxBytes, uint64(len(elem.packet)))
 		_, err := device.tun.device.Write(elem.buffer[:offset+len(elem.packet)], offset)
 		if err == nil {
 			shouldFlush = true

device/send.go

@@ -600,7 +600,6 @@ func (peer *Peer) RoutineSequentialSender() {
 
 			// send message and return buffer to pool
 
-			length := uint64(len(elem.packet))
 			err := peer.SendBuffer(elem.packet)
 			if len(elem.packet) != MessageKeepaliveSize {
 				peer.timersDataSent()
@@ -611,7 +610,6 @@ func (peer *Peer) RoutineSequentialSender() {
 				logError.Println(peer, "- Failed to send data packet", err)
 				continue
 			}
-			atomic.AddUint64(&peer.stats.txBytes, length)
 
 			peer.keepKeyFreshSending()
 		}