rename IncomingPacketAckHandler to ReceivedPacketHandler

ackhandler/received_packet_handler.go

@@ -0,0 +1,93 @@
+package ackhandler
+
+import (
+	"errors"
+
+	"github.com/lucas-clemente/quic-go/frames"
+	"github.com/lucas-clemente/quic-go/protocol"
+)
+
+var ErrDuplicatePacket = errors.New("ReceivedPacketHandler: Duplicate Packet")
+
+type receivedPacketHandler struct {
+	highestInOrderObserved        protocol.PacketNumber
+	highestInOrderObservedEntropy EntropyAccumulator
+	largestObserved               protocol.PacketNumber
+	packetHistory                 map[protocol.PacketNumber]bool // the bool is the EntropyBit of the packet
+}
+
+// NewReceivedPacketHandler creates a new receivedPacketHandler
+func NewReceivedPacketHandler() ReceivedPacketHandler {
+	return &receivedPacketHandler{
+		packetHistory: make(map[protocol.PacketNumber]bool),
+	}
+}
+
+func (h *receivedPacketHandler) ReceivedPacket(packetNumber protocol.PacketNumber, entropyBit bool) error {
+	if packetNumber == 0 {
+		return errors.New("Invalid packet number")
+	}
+	if packetNumber <= h.highestInOrderObserved || h.packetHistory[packetNumber] {
+		return ErrDuplicatePacket
+	}
+
+	if packetNumber > h.largestObserved {
+		h.largestObserved = packetNumber
+	}
+
+	if packetNumber == h.highestInOrderObserved+1 {
+		h.highestInOrderObserved = packetNumber
+		h.highestInOrderObservedEntropy.Add(packetNumber, entropyBit)
+	}
+
+	h.packetHistory[packetNumber] = entropyBit
+	return nil
+}
+
+func (h *receivedPacketHandler) ReceivedStopWaiting(f *frames.StopWaitingFrame) error {
+	// Ignore if STOP_WAITING is unneeded
+	if h.highestInOrderObserved >= f.LeastUnacked {
+		return nil
+	}
+
+	h.highestInOrderObserved = f.LeastUnacked
+	h.highestInOrderObservedEntropy = EntropyAccumulator(f.Entropy)
+
+	return nil
+}
+
+// getNackRanges gets all the NACK ranges
+func (h *receivedPacketHandler) getNackRanges() ([]frames.NackRange, EntropyAccumulator) {
+	// ToDo: use a better data structure here
+	var ranges []frames.NackRange
+	inRange := false
+	entropy := h.highestInOrderObservedEntropy
+	for i := h.highestInOrderObserved + 1; i <= h.largestObserved; i++ {
+		entropyBit, ok := h.packetHistory[i]
+		if !ok {
+			if !inRange {
+				r := frames.NackRange{
+					FirstPacketNumber: i,
+					LastPacketNumber:  i,
+				}
+				ranges = append(ranges, r)
+				inRange = true
+			} else {
+				ranges[len(ranges)-1].LastPacketNumber++
+			}
+		} else {
+			inRange = false
+			entropy.Add(i, entropyBit)
+		}
+	}
+	return ranges, entropy
+}
+
+func (h *receivedPacketHandler) DequeueAckFrame() *frames.AckFrame {
+	nackRanges, entropy := h.getNackRanges()
+	return &frames.AckFrame{
+		LargestObserved: h.largestObserved,
+		Entropy:         byte(entropy),
+		NackRanges:      nackRanges,
+	}
+}