add basic AckHandler

ackhandler/ack_handler.go

@@ -0,0 +1,52 @@
+package ackhandler
+
+import "github.com/lucas-clemente/quic-go/protocol"
+
+// The AckHandler handles ACKs
+type AckHandler struct {
+	LargestObserved protocol.PacketNumber
+	Observed        map[protocol.PacketNumber]bool
+}
+
+// NewAckHandler creates a new AckHandler
+func NewAckHandler() (*AckHandler, error) {
+	ackHandler := &AckHandler{
+		Observed: make(map[protocol.PacketNumber]bool),
+	}
+	return ackHandler, nil
+}
+
+// HandlePacket handles a packet
+func (h *AckHandler) HandlePacket(packetNumber protocol.PacketNumber) {
+	if packetNumber > h.LargestObserved {
+		h.LargestObserved = packetNumber
+	}
+	h.Observed[packetNumber] = true
+}
+
+// GetNackRanges gets all the NACK ranges
+func (h *AckHandler) GetNackRanges() []*NackRange {
+	// ToDo: improve performance
+	var ranges []*NackRange
+	inRange := false
+	// ToDo: fix types
+	for i := 0; i < int(h.LargestObserved); i++ {
+		packetNumber := protocol.PacketNumber(i)
+		_, ok := h.Observed[packetNumber]
+		if !ok {
+			if !inRange {
+				r := &NackRange{
+					FirstPacketNumber: packetNumber,
+					Length:            1,
+				}
+				ranges = append(ranges, r)
+				inRange = true
+			} else {
+				ranges[len(ranges)-1].Length++
+			}
+		} else {
+			inRange = false
+		}
+	}
+	return ranges
+}