/
received_packet_handler.go
164 lines (130 loc) · 4.47 KB
/
received_packet_handler.go
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package ackhandler
import (
"errors"
"time"
"github.com/lucas-clemente/quic-go/internal/protocol"
"github.com/lucas-clemente/quic-go/internal/wire"
)
var errInvalidPacketNumber = errors.New("ReceivedPacketHandler: Invalid packet number")
type receivedPacketHandler struct {
largestObserved protocol.PacketNumber
lowerLimit protocol.PacketNumber
largestObservedReceivedTime time.Time
packetHistory *receivedPacketHistory
ackSendDelay time.Duration
packetsReceivedSinceLastAck int
retransmittablePacketsReceivedSinceLastAck int
ackQueued bool
ackAlarm time.Time
lastAck *wire.AckFrame
version protocol.VersionNumber
packets uint64
}
// NewReceivedPacketHandler creates a new receivedPacketHandler
func NewReceivedPacketHandler(version protocol.VersionNumber) ReceivedPacketHandler {
return &receivedPacketHandler{
packetHistory: newReceivedPacketHistory(),
ackSendDelay: protocol.AckSendDelay,
version: version,
}
}
func (h *receivedPacketHandler) GetStatistics() uint64 {
return h.packets
}
func (h *receivedPacketHandler) ReceivedPacket(packetNumber protocol.PacketNumber, shouldInstigateAck bool) error {
if packetNumber == 0 {
return errInvalidPacketNumber
}
// A new packet was received on that path and passes checks, so count it for stats
h.packets++
if packetNumber > h.largestObserved {
h.largestObserved = packetNumber
h.largestObservedReceivedTime = time.Now()
}
if packetNumber <= h.lowerLimit {
return nil
}
if err := h.packetHistory.ReceivedPacket(packetNumber); err != nil {
return err
}
h.maybeQueueAck(packetNumber, shouldInstigateAck)
return nil
}
// SetLowerLimit sets a lower limit for acking packets.
// Packets with packet numbers smaller or equal than p will not be acked.
func (h *receivedPacketHandler) SetLowerLimit(p protocol.PacketNumber) {
h.lowerLimit = p
h.packetHistory.DeleteUpTo(p)
}
func (h *receivedPacketHandler) maybeQueueAck(packetNumber protocol.PacketNumber, shouldInstigateAck bool) {
h.packetsReceivedSinceLastAck++
if shouldInstigateAck {
h.retransmittablePacketsReceivedSinceLastAck++
}
// always ack the first packet
if h.lastAck == nil {
h.ackQueued = true
}
if h.version < protocol.Version39 {
// Always send an ack every 20 packets in order to allow the peer to discard
// information from the SentPacketManager and provide an RTT measurement.
// From QUIC 39, this is not needed anymore, since the peer will regularly send a retransmittable packet.
if h.packetsReceivedSinceLastAck >= protocol.MaxPacketsReceivedBeforeAckSend {
h.ackQueued = true
}
}
// if the packet number is smaller than the largest acked packet, it must have been reported missing with the last ACK
// note that it cannot be a duplicate because they're already filtered out by ReceivedPacket()
if h.lastAck != nil && packetNumber < h.lastAck.LargestAcked {
h.ackQueued = true
}
// check if a new missing range above the previously was created
if h.lastAck != nil && h.packetHistory.GetHighestAckRange().First > h.lastAck.LargestAcked {
h.ackQueued = true
}
if !h.ackQueued && shouldInstigateAck {
if h.retransmittablePacketsReceivedSinceLastAck >= protocol.RetransmittablePacketsBeforeAck {
h.ackQueued = true
} else {
if h.ackAlarm.IsZero() {
h.ackAlarm = time.Now().Add(h.ackSendDelay)
}
}
}
if h.ackQueued {
// cancel the ack alarm
h.ackAlarm = time.Time{}
}
}
func (h *receivedPacketHandler) GetAckFrame() *wire.AckFrame {
if !h.ackQueued && (h.ackAlarm.IsZero() || h.ackAlarm.After(time.Now())) {
return nil
}
ackRanges := h.packetHistory.GetAckRanges()
ack := &wire.AckFrame{
LargestAcked: h.largestObserved,
LowestAcked: ackRanges[len(ackRanges)-1].First,
PacketReceivedTime: h.largestObservedReceivedTime,
}
if len(ackRanges) > 1 {
ack.AckRanges = ackRanges
}
h.lastAck = ack
h.ackAlarm = time.Time{}
h.ackQueued = false
h.packetsReceivedSinceLastAck = 0
h.retransmittablePacketsReceivedSinceLastAck = 0
return ack
}
func (h *receivedPacketHandler) GetClosePathFrame() *wire.ClosePathFrame {
ackRanges := h.packetHistory.GetAckRanges()
frame := &wire.ClosePathFrame{
LargestAcked: h.largestObserved,
LowestAcked: ackRanges[len(ackRanges)-1].First,
}
if len(ackRanges) > 1 {
frame.AckRanges = ackRanges
}
return frame
}
func (h *receivedPacketHandler) GetAlarmTimeout() time.Time { return h.ackAlarm }