forked from quic-go/quic-go
calculate expected entropy in seperate function for ReceivedAck
This commit is contained in:
Marten Seemann
@@ -8,6 +8,11 @@ import (
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"github.com/lucas-clemente/quic-go/protocol"
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)
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var (
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errEntropy = errors.New("OutgoingPacketAckHandler: Wrong entropy")
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errMapAccess = errors.New("OutgoingPacketAckHandler: Packet does not exist in PacketHistory")
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)
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type outgoingPacketAckHandler struct {
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lastSentPacketNumber protocol.PacketNumber
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highestInOrderAckedPacketNumber protocol.PacketNumber
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@@ -52,6 +57,60 @@ func (h *outgoingPacketAckHandler) SentPacket(packet *Packet) error {
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return nil
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}
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func (h *outgoingPacketAckHandler) calculateExpectedEntropy(ackFrame *frames.AckFrame) (EntropyAccumulator, error) {
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h.packetHistoryMutex.Lock()
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defer h.packetHistoryMutex.Unlock()
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highestInOrderAckedPacketNumber := ackFrame.GetHighestInOrderPacketNumber()
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var expectedEntropy EntropyAccumulator
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if !ackFrame.HasNACK() { // if the packet doesn't have NACKs, the correct entropy value is the entropy we sent the LargestObserved packet with. Just look it up in the map
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packet, ok := h.packetHistory[ackFrame.LargestObserved]
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if !ok {
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return 0, errMapAccess
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}
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expectedEntropy = packet.Entropy
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} else { // if the packet has NACKs, the entropy value has to be calculated
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// get the entropy for the highestInOrderAckedPacketNumber
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// There are two cases:
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// 1. the packet with highestInOrderAckedPacketNumber has already been ACKed, then it doesn't exist in the packetHistory map anymore, but the value was saved as h.highestInOrderAckedEntropy
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// 2. the packet with highestInOrderAckedPacketNumber has not yet been ACKed, then it should exist in the packetHistory map, and can just be read from there
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if highestInOrderAckedPacketNumber == h.highestInOrderAckedPacketNumber {
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expectedEntropy = h.highestInOrderAckedEntropy
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} else {
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packet, ok := h.packetHistory[highestInOrderAckedPacketNumber]
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if !ok {
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return 0, errMapAccess
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}
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expectedEntropy = packet.Entropy
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}
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nackRangeIndex := len(ackFrame.NackRanges) - 1
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nackRange := ackFrame.NackRanges[nackRangeIndex]
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for i := highestInOrderAckedPacketNumber + 1; i <= ackFrame.LargestObserved; i++ {
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// select correct NACK range
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if i > nackRange.LastPacketNumber {
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nackRangeIndex--
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if nackRangeIndex >= 0 {
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nackRange = ackFrame.NackRanges[nackRangeIndex]
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}
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}
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if i >= nackRange.FirstPacketNumber && i <= nackRange.LastPacketNumber { // PacketNumber i is contained in a NACK range, it's entropyBit is irrelevant
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continue
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}
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// PacketNumber i is not contained in a NACK range, it's entropyBit has to be considered
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packet, ok := h.packetHistory[i]
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if !ok {
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return 0, errMapAccess
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}
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expectedEntropy.Add(i, packet.EntropyBit)
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}
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}
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return expectedEntropy, nil
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}
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func (h *outgoingPacketAckHandler) ReceivedAck(ackFrame *frames.AckFrame) error {
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if ackFrame.LargestObserved > h.lastSentPacketNumber {
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return errors.New("OutgoingPacketAckHandler: Received ACK for an unsent package")
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@@ -61,80 +120,50 @@ func (h *outgoingPacketAckHandler) ReceivedAck(ackFrame *frames.AckFrame) error
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return nil
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}
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entropyError := errors.New("OutgoingPacketAckHandler: Wrong entropy")
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mapAccessError := errors.New("OutgoingPacketAckHandler: Packet does not exist in PacketHistory")
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h.packetHistoryMutex.Lock()
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defer h.packetHistoryMutex.Unlock()
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highestInOrderAckedEntropy := h.highestInOrderAckedEntropy
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highestInOrderAckedPacketNumber := ackFrame.GetHighestInOrderPacketNumber()
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for i := h.highestInOrderAckedPacketNumber + 1; i <= highestInOrderAckedPacketNumber; i++ {
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packet, ok := h.packetHistory[i]
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if !ok {
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return mapAccessError
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}
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highestInOrderAckedEntropy.Add(packet.PacketNumber, packet.EntropyBit)
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expectedEntropy, err := h.calculateExpectedEntropy(ackFrame)
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if err != nil {
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return err
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}
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var expectedEntropy EntropyAccumulator
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if !ackFrame.HasNACK() {
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packet, ok := h.packetHistory[ackFrame.LargestObserved]
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if !ok {
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return mapAccessError
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}
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expectedEntropy = packet.Entropy
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} else {
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if highestInOrderAckedPacketNumber == h.highestInOrderAckedPacketNumber {
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expectedEntropy = h.highestInOrderAckedEntropy
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} else {
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packet, ok := h.packetHistory[highestInOrderAckedPacketNumber]
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if !ok {
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return mapAccessError
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}
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expectedEntropy = packet.Entropy
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}
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nackRangeIndex := len(ackFrame.NackRanges) - 1
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nackRange := ackFrame.NackRanges[nackRangeIndex]
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for i := highestInOrderAckedPacketNumber + 1; i <= ackFrame.LargestObserved; i++ {
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if i > nackRange.LastPacketNumber {
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nackRangeIndex--
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if nackRangeIndex >= 0 {
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nackRange = ackFrame.NackRanges[nackRangeIndex]
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}
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}
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if i >= nackRange.FirstPacketNumber && i <= nackRange.LastPacketNumber {
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continue
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}
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packet, ok := h.packetHistory[i]
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if !ok {
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return mapAccessError
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}
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expectedEntropy.Add(i, packet.EntropyBit)
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}
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}
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if ackFrame.Entropy != byte(expectedEntropy) {
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return entropyError
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if byte(expectedEntropy) != ackFrame.Entropy {
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return errEntropy
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}
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// Entropy ok. Now actually process the ACK packet
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h.packetHistoryMutex.Lock()
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defer h.packetHistoryMutex.Unlock()
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highestInOrderAckedPacketNumber := ackFrame.GetHighestInOrderPacketNumber()
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highestInOrderAckedEntropy := h.highestInOrderAckedEntropy
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// if this ACK increases the highestInOrderAckedPacketNumber, the packet will be deleted from the packetHistory map, thus we need to save it's Entropy before doing so
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if highestInOrderAckedPacketNumber > h.highestInOrderAckedPacketNumber {
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packet, ok := h.packetHistory[highestInOrderAckedPacketNumber]
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if !ok {
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return errMapAccess
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}
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highestInOrderAckedEntropy = packet.Entropy
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}
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// delete all packets below the highestInOrderAckedPacketNumber
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for i := h.highestInOrderAckedPacketNumber; i <= highestInOrderAckedPacketNumber; i++ {
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delete(h.packetHistory, i)
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}
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// delete packets with a packet number higher than highestInOrderAckedPacketNumber that have already been ACKed
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// this is the case if the PacketNumber is *not* contained in any of the NACK ranges
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if ackFrame.HasNACK() {
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nackRangeIndex := len(ackFrame.NackRanges) - 1
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nackRange := ackFrame.NackRanges[nackRangeIndex]
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for i := highestInOrderAckedPacketNumber + 1; i <= ackFrame.LargestObserved; i++ {
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// select correct NACK range
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if i > nackRange.LastPacketNumber {
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nackRangeIndex--
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if nackRangeIndex >= 0 {
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nackRange = ackFrame.NackRanges[nackRangeIndex]
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}
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}
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// PacketNumber i is not contained in a NACK range
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if i >= nackRange.FirstPacketNumber && i <= nackRange.LastPacketNumber {
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continue
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}
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@@ -144,6 +173,7 @@ func (h *outgoingPacketAckHandler) ReceivedAck(ackFrame *frames.AckFrame) error
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h.highestInOrderAckedPacketNumber = highestInOrderAckedPacketNumber
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h.highestInOrderAckedEntropy = highestInOrderAckedEntropy
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return nil
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}
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