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handle ACKs for packet number 0

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This commit is contained in:
Marten Seemann
2017-12-04 12:34:05 +07:00
parent 0219193a07
commit 2905a37928
2 changed files with 67 additions and 56 deletions
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18
ackhandler/sent_packet_handler.go
View File

@@ -83,11 +83,11 @@ func NewSentPacketHandler(rttStats *congestion.RTTStats) SentPacketHandler {
}
}
func (h *sentPacketHandler) largestInOrderAcked() protocol.PacketNumber {
func (h *sentPacketHandler) lowestUnacked() protocol.PacketNumber {
if f := h.packetHistory.Front(); f != nil {
return f.Value.PacketNumber - 1
return f.Value.PacketNumber
}
return h.largestAcked
return h.largestAcked + 1
}
func (h *sentPacketHandler) ShouldSendRetransmittablePacket() bool {
@@ -144,13 +144,16 @@ func (h *sentPacketHandler) ReceivedAck(ackFrame *wire.AckFrame, withPacketNumbe
}
// duplicate or out-of-order ACK
// if withPacketNumber <= h.largestReceivedPacketWithAck && withPacketNumber != 0 {
if withPacketNumber <= h.largestReceivedPacketWithAck {
utils.Debugf("ignoring ack because duplicate")
return ErrDuplicateOrOutOfOrderAck
}
h.largestReceivedPacketWithAck = withPacketNumber
// ignore repeated ACK (ACKs that don't have a higher LargestAcked than the last ACK)
if ackFrame.LargestAcked <= h.largestInOrderAcked() {
if ackFrame.LargestAcked < h.lowestUnacked() {
utils.Debugf("ignoring ack because repeated")
return nil
}
h.largestAcked = ackFrame.LargestAcked
@@ -223,7 +226,6 @@ func (h *sentPacketHandler) determineNewlyAckedPackets(ackFrame *wire.AckFrame)
ackedPackets = append(ackedPackets, el)
}
}
return ackedPackets, nil
}
@@ -335,7 +337,7 @@ func (h *sentPacketHandler) DequeuePacketForRetransmission() *Packet {
}
func (h *sentPacketHandler) GetLeastUnacked() protocol.PacketNumber {
return h.largestInOrderAcked() + 1
return h.lowestUnacked()
}
func (h *sentPacketHandler) GetStopWaitingFrame(force bool) *wire.StopWaitingFrame {
@@ -430,10 +432,10 @@ func (h *sentPacketHandler) skippedPacketsAcked(ackFrame *wire.AckFrame) bool {
}
func (h *sentPacketHandler) garbageCollectSkippedPackets() {
lioa := h.largestInOrderAcked()
lowestUnacked := h.lowestUnacked()
deleteIndex := 0
for i, p := range h.skippedPackets {
if p <= lioa {
if p < lowestUnacked {
deleteIndex = i + 1
}
}

105
ackhandler/sent_packet_handler_test.go
View File

@@ -124,6 +124,21 @@ var _ = Describe("SentPacketHandler", func() {
Expect(handler.skippedPackets).To(BeEmpty())
})
It("accepts packet number 0", func() {
packet1 := Packet{PacketNumber: 0, Frames: []wire.Frame{&streamFrame}, Length: 1}
packet2 := Packet{PacketNumber: 1, Frames: []wire.Frame{&streamFrame}, Length: 2}
err := handler.SentPacket(&packet1)
Expect(err).ToNot(HaveOccurred())
Expect(handler.lastSentPacketNumber).To(BeZero())
err = handler.SentPacket(&packet2)
Expect(err).ToNot(HaveOccurred())
Expect(handler.lastSentPacketNumber).To(Equal(protocol.PacketNumber(1)))
Expect(handler.packetHistory.Front().Value.PacketNumber).To(Equal(protocol.PacketNumber(0)))
Expect(handler.packetHistory.Back().Value.PacketNumber).To(Equal(protocol.PacketNumber(1)))
Expect(handler.bytesInFlight).To(Equal(protocol.ByteCount(3)))
Expect(handler.skippedPackets).To(BeEmpty())
})
It("stores the sent time", func() {
packet := Packet{PacketNumber: 1, Frames: []wire.Frame{&streamFrame}, Length: 1}
err := handler.SentPacket(&packet)
@@ -259,6 +274,7 @@ var _ = Describe("SentPacketHandler", func() {
BeforeEach(func() {
packets = []*Packet{
{PacketNumber: 0, Frames: []wire.Frame{&streamFrame}, Length: 1},
{PacketNumber: 1, Frames: []wire.Frame{&streamFrame}, Length: 1},
{PacketNumber: 2, Frames: []wire.Frame{&streamFrame}, Length: 1},
{PacketNumber: 3, Frames: []wire.Frame{&streamFrame}, Length: 1},
@@ -280,6 +296,14 @@ var _ = Describe("SentPacketHandler", func() {
Expect(handler.bytesInFlight).To(Equal(protocol.ByteCount(len(packets))))
})
expectInPacketHistory := func(expected []protocol.PacketNumber) {
var packets []protocol.PacketNumber
for el := handler.packetHistory.Front(); el != nil; el = el.Next() {
packets = append(packets, el.Value.PacketNumber)
}
ExpectWithOffset(1, packets).To(Equal(expected))
}
Context("ACK validation", func() {
It("rejects duplicate ACKs", func() {
largestAcked := 3
@@ -296,16 +320,15 @@ var _ = Describe("SentPacketHandler", func() {
})
It("rejects out of order ACKs", func() {
ack := wire.AckFrame{
LargestAcked: 3,
}
// acks packets 0, 1, 2, 3
ack := wire.AckFrame{LargestAcked: 3}
err := handler.ReceivedAck(&ack, 1337, protocol.EncryptionUnencrypted, time.Now())
Expect(err).ToNot(HaveOccurred())
Expect(handler.bytesInFlight).To(Equal(protocol.ByteCount(len(packets) - 3)))
Expect(handler.bytesInFlight).To(Equal(protocol.ByteCount(len(packets) - 4)))
err = handler.ReceivedAck(&ack, 1337-1, protocol.EncryptionUnencrypted, time.Now())
Expect(err).To(MatchError(ErrDuplicateOrOutOfOrderAck))
Expect(handler.largestAcked).To(Equal(protocol.PacketNumber(3)))
Expect(handler.bytesInFlight).To(Equal(protocol.ByteCount(len(packets) - 3)))
Expect(handler.bytesInFlight).To(Equal(protocol.ByteCount(len(packets) - 4)))
})
It("rejects ACKs with a too high LargestAcked packet number", func() {
@@ -359,7 +382,7 @@ var _ = Describe("SentPacketHandler", func() {
It("adjusts the LargestAcked", func() {
ack := wire.AckFrame{
LargestAcked: 5,
LowestAcked: 1,
LowestAcked: 0,
}
err := handler.ReceivedAck(&ack, 1, protocol.EncryptionUnencrypted, time.Now())
Expect(err).ToNot(HaveOccurred())
@@ -388,15 +411,15 @@ var _ = Describe("SentPacketHandler", func() {
Expect(err).To(MatchError("Received ACK with encryption level encrypted (not forward-secure) that acks a packet 13 (encryption level forward-secure)"))
})
It("ACKs all packets for an ACK frame with no missing packets", func() {
It("acks all packets for an ACK frame with no missing packets", func() {
ack := wire.AckFrame{
LargestAcked: 8,
LowestAcked: 2,
LowestAcked: 1,
}
err := handler.ReceivedAck(&ack, 1, protocol.EncryptionUnencrypted, time.Now())
Expect(err).ToNot(HaveOccurred())
el := handler.packetHistory.Front()
Expect(el.Value.PacketNumber).To(Equal(protocol.PacketNumber(1)))
Expect(el.Value.PacketNumber).To(Equal(protocol.PacketNumber(0)))
el = el.Next()
Expect(el.Value.PacketNumber).To(Equal(protocol.PacketNumber(9)))
el = el.Next()
@@ -404,26 +427,28 @@ var _ = Describe("SentPacketHandler", func() {
Expect(el.Next().Value.PacketNumber).To(Equal(protocol.PacketNumber(12)))
})
It("acks packet 0", func() {
ack := wire.AckFrame{
LargestAcked: 0,
LowestAcked: 0,
}
err := handler.ReceivedAck(&ack, 1, protocol.EncryptionUnencrypted, time.Now())
Expect(err).ToNot(HaveOccurred())
expectInPacketHistory([]protocol.PacketNumber{1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12})
})
It("handles an ACK frame with one missing packet range", func() {
ack := wire.AckFrame{
LargestAcked: 9,
LowestAcked: 2,
LowestAcked: 1,
AckRanges: []wire.AckRange{ // packets 4 and 5 were lost
{First: 6, Last: 9},
{First: 2, Last: 3},
{First: 1, Last: 3},
},
}
err := handler.ReceivedAck(&ack, 1, protocol.EncryptionUnencrypted, time.Now())
Expect(err).ToNot(HaveOccurred())
el := handler.packetHistory.Front()
Expect(el.Value.PacketNumber).To(Equal(protocol.PacketNumber(1)))
el = el.Next()
Expect(el.Value.PacketNumber).To(Equal(protocol.PacketNumber(4)))
el = el.Next()
Expect(el.Value.PacketNumber).To(Equal(protocol.PacketNumber(5)))
el = el.Next()
Expect(el.Value.PacketNumber).To(Equal(protocol.PacketNumber(10)))
Expect(el.Next().Value.PacketNumber).To(Equal(protocol.PacketNumber(12)))
expectInPacketHistory([]protocol.PacketNumber{0, 4, 5, 10, 12})
})
It("does not ack packets below the LowestAcked", func() {
@@ -433,11 +458,7 @@ var _ = Describe("SentPacketHandler", func() {
}
err := handler.ReceivedAck(&ack, 1, protocol.EncryptionUnencrypted, time.Now())
Expect(err).ToNot(HaveOccurred())
el := handler.packetHistory.Front()
Expect(el.Value.PacketNumber).To(Equal(protocol.PacketNumber(1)))
el = el.Next()
Expect(el.Value.PacketNumber).To(Equal(protocol.PacketNumber(2)))
Expect(el.Next().Value.PacketNumber).To(Equal(protocol.PacketNumber(9)))
expectInPacketHistory([]protocol.PacketNumber{0, 1, 2, 9, 10, 12})
})
It("handles an ACK with multiple missing packet ranges", func() {
@@ -453,16 +474,7 @@ var _ = Describe("SentPacketHandler", func() {
}
err := handler.ReceivedAck(&ack, 1, protocol.EncryptionUnencrypted, time.Now())
Expect(err).ToNot(HaveOccurred())
el := handler.packetHistory.Front()
Expect(el.Value.PacketNumber).To(Equal(protocol.PacketNumber(2)))
el = el.Next()
Expect(el.Value.PacketNumber).To(Equal(protocol.PacketNumber(4)))
el = el.Next()
Expect(el.Value.PacketNumber).To(Equal(protocol.PacketNumber(5)))
el = el.Next()
Expect(el.Value.PacketNumber).To(Equal(protocol.PacketNumber(8)))
el = el.Next()
Expect(el.Value.PacketNumber).To(Equal(protocol.PacketNumber(10)))
expectInPacketHistory([]protocol.PacketNumber{0, 2, 4, 5, 8, 10, 12})
})
It("processes an ACK frame that would be sent after a late arrival of a packet", func() {
@@ -478,8 +490,7 @@ var _ = Describe("SentPacketHandler", func() {
err := handler.ReceivedAck(&ack1, 1, protocol.EncryptionUnencrypted, time.Now())
Expect(err).ToNot(HaveOccurred())
Expect(handler.bytesInFlight).To(Equal(protocol.ByteCount(len(packets) - 5)))
el := handler.packetHistory.Front()
Expect(el.Value.PacketNumber).To(Equal(protocol.PacketNumber(3)))
expectInPacketHistory([]protocol.PacketNumber{0, 3, 7, 8, 9, 10, 12})
ack2 := wire.AckFrame{
LargestAcked: protocol.PacketNumber(largestObserved),
LowestAcked: 1,
@@ -487,31 +498,30 @@ var _ = Describe("SentPacketHandler", func() {
err = handler.ReceivedAck(&ack2, 2, protocol.EncryptionUnencrypted, time.Now())
Expect(err).ToNot(HaveOccurred())
Expect(handler.bytesInFlight).To(Equal(protocol.ByteCount(len(packets) - 6)))
Expect(handler.packetHistory.Front().Value.PacketNumber).To(Equal(protocol.PacketNumber(7)))
expectInPacketHistory([]protocol.PacketNumber{0, 7, 8, 9, 10, 12})
})
It("processes an ACK frame that would be sent after a late arrival of a packet and another packet", func() {
ack1 := wire.AckFrame{
LargestAcked: 6,
LowestAcked: 1,
LowestAcked: 0,
AckRanges: []wire.AckRange{
{First: 4, Last: 6},
{First: 1, Last: 2},
{First: 0, Last: 2},
},
}
err := handler.ReceivedAck(&ack1, 1, protocol.EncryptionUnencrypted, time.Now())
Expect(err).ToNot(HaveOccurred())
Expect(handler.bytesInFlight).To(Equal(protocol.ByteCount(len(packets) - 5)))
el := handler.packetHistory.Front()
Expect(el.Value.PacketNumber).To(Equal(protocol.PacketNumber(3)))
Expect(handler.bytesInFlight).To(Equal(protocol.ByteCount(len(packets) - 6)))
expectInPacketHistory([]protocol.PacketNumber{3, 7, 8, 9, 10, 12})
ack2 := wire.AckFrame{
LargestAcked: 7,
LowestAcked: 1,
}
err = handler.ReceivedAck(&ack2, 2, protocol.EncryptionUnencrypted, time.Now())
Expect(err).ToNot(HaveOccurred())
Expect(handler.bytesInFlight).To(Equal(protocol.ByteCount(len(packets) - 7)))
Expect(handler.packetHistory.Front().Value.PacketNumber).To(Equal(protocol.PacketNumber(8)))
Expect(handler.bytesInFlight).To(Equal(protocol.ByteCount(len(packets) - 8)))
expectInPacketHistory([]protocol.PacketNumber{8, 9, 10, 12})
})
It("processes an ACK that contains old ACK ranges", func() {
@@ -521,7 +531,7 @@ var _ = Describe("SentPacketHandler", func() {
}
err := handler.ReceivedAck(&ack1, 1, protocol.EncryptionUnencrypted, time.Now())
Expect(err).ToNot(HaveOccurred())
Expect(handler.packetHistory.Front().Value.PacketNumber).To(Equal(protocol.PacketNumber(7)))
expectInPacketHistory([]protocol.PacketNumber{0, 7, 8, 9, 10, 12})
Expect(handler.bytesInFlight).To(Equal(protocol.ByteCount(len(packets) - 6)))
ack2 := wire.AckFrame{
LargestAcked: 10,
@@ -535,8 +545,7 @@ var _ = Describe("SentPacketHandler", func() {
err = handler.ReceivedAck(&ack2, 2, protocol.EncryptionUnencrypted, time.Now())
Expect(err).ToNot(HaveOccurred())
Expect(handler.bytesInFlight).To(Equal(protocol.ByteCount(len(packets) - 6 - 3)))
Expect(handler.packetHistory.Front().Value.PacketNumber).To(Equal(protocol.PacketNumber(7)))
Expect(handler.packetHistory.Back().Value.PacketNumber).To(Equal(protocol.PacketNumber(12)))
expectInPacketHistory([]protocol.PacketNumber{0, 7, 12})
})
})