fix bug in switch actor's cleanRoot, strict nonce handling at the session level, and add separate queues per stream to the packetqueue code

src/yggdrasil/packetqueue.go

@@ -1,38 +1,125 @@
 package yggdrasil
 
-import "github.com/yggdrasil-network/yggdrasil-go/src/util"
+import (
+	"time"
+
+	"github.com/yggdrasil-network/yggdrasil-go/src/util"
+)
 
 // TODO take max size from config
-const MAX_PACKET_QUEUE_SIZE = 1048576 // 1 MB
+const MAX_PACKET_QUEUE_SIZE = 4 * 1048576 // 4 MB
+
+type pqStreamID string
+
+type pqPacketInfo struct {
+	packet []byte
+	time   time.Time
+}
+
+type pqStream struct {
+	infos []pqPacketInfo
+	size  uint64
+}
 
 // TODO separate queues per e.g. traffic flow
 type packetQueue struct {
-	packets [][]byte
-	size    uint32
+	streams map[pqStreamID]pqStream
+	size    uint64
 }
 
 func (q *packetQueue) cleanup() {
 	for q.size > MAX_PACKET_QUEUE_SIZE {
-		if packet, success := q.pop(); success {
+		// TODO? drop from a random stream
+		//  odds proportional to size? bandwidth?
+		//  always using the worst is exploitable -> flood 1 packet per random stream
+		// find the stream that's using the most bandwidth
+		now := time.Now()
+		var worst pqStreamID
+		for id := range q.streams {
+			worst = id
+			break // get a random ID to start
+		}
+		worstStream := q.streams[worst]
+		worstSize := float64(worstStream.size)
+		worstAge := now.Sub(worstStream.infos[0].time).Seconds()
+		for id, stream := range q.streams {
+			thisSize := float64(stream.size)
+			thisAge := now.Sub(stream.infos[0].time).Seconds()
+			// cross multiply to avoid division by zero issues
+			if worstSize*thisAge < thisSize*worstAge {
+				// worstSize/worstAge < thisSize/thisAge -> this uses more bandwidth
+				worst = id
+				worstStream = stream
+				worstSize = thisSize
+				worstAge = thisAge
+			}
+		}
+		// Drop the oldest packet from the worst stream
+		packet := worstStream.infos[0].packet
+		worstStream.infos = worstStream.infos[1:]
+		worstStream.size -= uint64(len(packet))
+		q.size -= uint64(len(packet))
 		util.PutBytes(packet)
+		// save the modified stream to queues
+		if len(worstStream.infos) > 0 {
+			q.streams[worst] = worstStream
 		} else {
-			panic("attempted to drop packet from empty queue")
-			break
+			delete(q.streams, worst)
 		}
 	}
 }
 
 func (q *packetQueue) push(packet []byte) {
-	q.packets = append(q.packets, packet)
-	q.size += uint32(len(packet))
+	if q.streams == nil {
+		q.streams = make(map[pqStreamID]pqStream)
+	}
+	// get stream
+	id := pqStreamID(peer_getPacketCoords(packet)) // just coords for now
+	stream := q.streams[id]
+	// update stream
+	stream.infos = append(stream.infos, pqPacketInfo{packet, time.Now()})
+	stream.size += uint64(len(packet))
+	// save update to queues
+	q.streams[id] = stream
+	q.size += uint64(len(packet))
 	q.cleanup()
 }
 
 func (q *packetQueue) pop() ([]byte, bool) {
-	if len(q.packets) > 0 {
-		packet := q.packets[0]
-		q.packets = q.packets[1:]
-		q.size -= uint32(len(packet))
+	if len(q.streams) > 0 {
+		// get the stream that uses the least bandwidth
+		now := time.Now()
+		var best pqStreamID
+		for id := range q.streams {
+			best = id
+			break // get a random ID to start
+		}
+		bestStream := q.streams[best]
+		bestSize := float64(bestStream.size)
+		bestAge := now.Sub(bestStream.infos[0].time).Seconds()
+		for id, stream := range q.streams {
+			thisSize := float64(stream.size)
+			thisAge := now.Sub(stream.infos[0].time).Seconds()
+			// cross multiply to avoid division by zero issues
+			if bestSize*thisAge > thisSize*bestAge {
+				// bestSize/bestAge > thisSize/thisAge -> this uses less bandwidth
+				best = id
+				bestStream = stream
+				bestSize = thisSize
+				bestAge = thisAge
+			}
+		}
+		// get the oldest packet from the best stream
+		packet := bestStream.infos[0].packet
+		bestStream.infos = bestStream.infos[1:]
+		bestStream.size -= uint64(len(packet))
+		q.size -= uint64(len(packet))
+		// save the modified stream to queues
+		if len(bestStream.infos) > 0 {
+			q.streams[best] = bestStream
+		} else {
+			delete(q.streams, best)
+		}
 		return packet, true
 	}
 	return nil, false

src/yggdrasil/session.go

@@ -16,9 +16,6 @@ import (
 	"github.com/Arceliar/phony"
 )
 
-// Duration that we keep track of old nonces per session, to allow some out-of-order packet delivery
-const nonceWindow = time.Second
-
 // All the information we know about an active session.
 // This includes coords, permanent and ephemeral keys, handles and nonces, various sorts of timing information for timeout and maintenance, and some metadata for the admin API.
 type sessionInfo struct {
@@ -394,14 +391,9 @@ func (sinfo *sessionInfo) _getMTU() MTU {
 	return sinfo.myMTU
 }
 
-// Checks if a packet's nonce is recent enough to fall within the window of allowed packets, and not already received.
+// Checks if a packet's nonce is newer than any previously received
 func (sinfo *sessionInfo) _nonceIsOK(theirNonce *crypto.BoxNonce) bool {
-	// The bitmask is to allow for some non-duplicate out-of-order packets
-	if theirNonce.Minus(&sinfo.theirNonce) > 0 {
-		// This is newer than the newest nonce we've seen
-		return true
-	}
-	return time.Since(sinfo.time) < nonceWindow
+	return theirNonce.Minus(&sinfo.theirNonce) > 0
 }
 
 // Updates the nonce mask by (possibly) shifting the bitmask and setting the bit corresponding to this nonce to 1, and then updating the most recent nonce

src/yggdrasil/switch.go

@@ -227,10 +227,10 @@ func (t *switchTable) _cleanRoot() {
 		t.time = now
 		if t.data.locator.root != t.key {
 			t.data.seq++
-			defer t._updateTable()
-			t.core.router.reset(nil)
+			defer t.core.router.reset(nil)
 		}
 		t.data.locator = switchLocator{root: t.key, tstamp: now.Unix()}
+		t._updateTable() // updates base copy of switch msg in lookupTable
 		t.core.peers.sendSwitchMsgs(t)
 	}
 }