From 4ad62aaa6aa269f08c0fdc9c139e6d5417e21746 Mon Sep 17 00:00:00 2001
From: Mathias Hall-Andersen <mathias@hall-andersen.dk>
Date: Sat, 8 Jul 2017 23:51:26 +0200
Subject: Improved timer state machine

---
 src/send.go | 58 ++++++++++++++++++++++++++++++++++++++--------------------
 1 file changed, 38 insertions(+), 20 deletions(-)

(limited to 'src/send.go')

diff --git a/src/send.go b/src/send.go
index a02f5cb..5ea9a8f 100644
--- a/src/send.go
+++ b/src/send.go
@@ -31,7 +31,7 @@ import (
  * (to allow the construction of transport messages in-place)
  */
 type QueueOutboundElement struct {
-	state   uint32
+	dropped int32
 	mutex   sync.Mutex
 	data    [MaxMessageSize]byte
 	packet  []byte   // slice of "data" (always!)
@@ -61,11 +61,11 @@ func (device *Device) NewOutboundElement() *QueueOutboundElement {
 }
 
 func (elem *QueueOutboundElement) Drop() {
-	atomic.StoreUint32(&elem.state, ElementStateDropped)
+	atomic.StoreInt32(&elem.dropped, AtomicTrue)
 }
 
 func (elem *QueueOutboundElement) IsDropped() bool {
-	return atomic.LoadUint32(&elem.state) == ElementStateDropped
+	return atomic.LoadInt32(&elem.dropped) == AtomicTrue
 }
 
 func addToOutboundQueue(
@@ -86,6 +86,25 @@ func addToOutboundQueue(
 	}
 }
 
+func addToEncryptionQueue(
+	queue chan *QueueOutboundElement,
+	element *QueueOutboundElement,
+) {
+	for {
+		select {
+		case queue <- element:
+			return
+		default:
+			select {
+			case old := <-queue:
+				old.Drop()
+				old.mutex.Unlock()
+			default:
+			}
+		}
+	}
+}
+
 /* Reads packets from the TUN and inserts
  * into nonce queue for peer
  *
@@ -196,9 +215,7 @@ func (peer *Peer) RoutineNonce() {
 						break
 					}
 				}
-				logDebug.Println("Key pair:", keyPair)
-
-				sendSignal(peer.signal.handshakeBegin)
+				signalSend(peer.signal.handshakeBegin)
 				logDebug.Println("Waiting for key-pair, peer", peer.id)
 
 				select {
@@ -225,12 +242,13 @@ func (peer *Peer) RoutineNonce() {
 
 				elem.keyPair = keyPair
 				elem.nonce = atomic.AddUint64(&keyPair.sendNonce, 1) - 1
+				elem.dropped = AtomicFalse
 				elem.peer = peer
 				elem.mutex.Lock()
 
-				// add to parallel processing and sequential consuming queue
+				// add to parallel and sequential queue
 
-				addToOutboundQueue(device.queue.encryption, elem)
+				addToEncryptionQueue(device.queue.encryption, elem)
 				addToOutboundQueue(peer.queue.outbound, elem)
 				elem = nil
 			}
@@ -246,6 +264,9 @@ func (peer *Peer) RoutineNonce() {
 func (device *Device) RoutineEncryption() {
 	var nonce [chacha20poly1305.NonceSize]byte
 	for work := range device.queue.encryption {
+
+		// check if dropped
+
 		if work.IsDropped() {
 			continue
 		}
@@ -289,25 +310,25 @@ func (device *Device) RoutineEncryption() {
  * The routine terminates then the outbound queue is closed.
  */
 func (peer *Peer) RoutineSequentialSender() {
-	logDebug := peer.device.log.Debug
-	logDebug.Println("Routine, sequential sender, started for peer", peer.id)
-
 	device := peer.device
 
+	logDebug := device.log.Debug
+	logDebug.Println("Routine, sequential sender, started for peer", peer.id)
+
 	for {
 		select {
 		case <-peer.signal.stop:
 			logDebug.Println("Routine, sequential sender, stopped for peer", peer.id)
 			return
 		case work := <-peer.queue.outbound:
+			work.mutex.Lock()
 			if work.IsDropped() {
 				continue
 			}
-			work.mutex.Lock()
+
 			func() {
-				if work.packet == nil {
-					return
-				}
+
+				// send to endpoint
 
 				peer.mutex.RLock()
 				defer peer.mutex.RUnlock()
@@ -331,12 +352,9 @@ func (peer *Peer) RoutineSequentialSender() {
 				}
 				atomic.AddUint64(&peer.txBytes, uint64(len(work.packet)))
 
-				// shift keep-alive timer
+				// reset keep-alive (passive keep-alives / acknowledgements)
 
-				if peer.persistentKeepaliveInterval != 0 {
-					interval := time.Duration(peer.persistentKeepaliveInterval) * time.Second
-					peer.timer.sendKeepalive.Reset(interval)
-				}
+				peer.TimerResetKeepalive()
 			}()
 		}
 	}
-- 
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