Improved handling of key-material

src/send.go

@@ -349,12 +349,19 @@ func (device *Device) RoutineEncryption() {
 		// encrypt content (append to header)
 
 		binary.LittleEndian.PutUint64(nonce[4:], elem.nonce)
-		elem.packet = elem.keyPair.send.Seal(
-			header,
-			nonce[:],
-			elem.packet,
-			nil,
-		)
+		elem.keyPair.send.mutex.RLock()
+		if elem.keyPair.send.aead == nil {
+			// very unlikely (the key was deleted during queuing)
+			elem.Drop()
+		} else {
+			elem.packet = elem.keyPair.send.aead.Seal(
+				header,
+				nonce[:],
+				elem.packet,
+				nil,
+			)
+		}
+		elem.keyPair.send.mutex.RUnlock()
 		elem.mutex.Unlock()
 
 		// refresh key if necessary