forked from quic-go/quic-go
-
Notifications
You must be signed in to change notification settings - Fork 0
/
received_packet_handler.go
166 lines (133 loc) · 4.96 KB
/
received_packet_handler.go
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
package ackhandler
import (
"errors"
"time"
"github.com/lucas-clemente/quic-go/frames"
"github.com/lucas-clemente/quic-go/protocol"
)
var (
// ErrDuplicatePacket occurres when a duplicate packet is received
ErrDuplicatePacket = errors.New("ReceivedPacketHandler: Duplicate Packet")
// ErrPacketSmallerThanLastStopWaiting occurs when a packet arrives with a packet number smaller than the largest LeastUnacked of a StopWaitingFrame. If this error occurs, the packet should be ignored
ErrPacketSmallerThanLastStopWaiting = errors.New("ReceivedPacketHandler: Packet number smaller than highest StopWaiting")
)
var errInvalidPacketNumber = errors.New("ReceivedPacketHandler: Invalid packet number")
type receivedPacketHandler struct {
largestObserved protocol.PacketNumber
ignorePacketsBelow protocol.PacketNumber
largestObservedReceivedTime time.Time
packetHistory *receivedPacketHistory
ackSendDelay time.Duration
packetsReceivedSinceLastAck int
retransmittablePacketsReceivedSinceLastAck int
ackQueued bool
ackAlarm time.Time
ackAlarmResetCallback func(time.Time)
lastAck *frames.AckFrame
}
// NewReceivedPacketHandler creates a new receivedPacketHandler
func NewReceivedPacketHandler(ackAlarmResetCallback func(time.Time)) ReceivedPacketHandler {
// create a stopped timer, see https://github.com/golang/go/issues/12721#issuecomment-143010182
timer := time.NewTimer(0)
<-timer.C
return &receivedPacketHandler{
packetHistory: newReceivedPacketHistory(),
ackAlarmResetCallback: ackAlarmResetCallback,
ackSendDelay: protocol.AckSendDelay,
}
}
func (h *receivedPacketHandler) ReceivedPacket(packetNumber protocol.PacketNumber, shouldInstigateAck bool) error {
if packetNumber == 0 {
return errInvalidPacketNumber
}
// if the packet number is smaller than the largest LeastUnacked value of a StopWaiting we received, we cannot detect if this packet has a duplicate number
// the packet has to be ignored anyway
if packetNumber <= h.ignorePacketsBelow {
return ErrPacketSmallerThanLastStopWaiting
}
if h.packetHistory.IsDuplicate(packetNumber) {
return ErrDuplicatePacket
}
err := h.packetHistory.ReceivedPacket(packetNumber)
if err != nil {
return err
}
if packetNumber > h.largestObserved {
h.largestObserved = packetNumber
h.largestObservedReceivedTime = time.Now()
}
h.maybeQueueAck(packetNumber, shouldInstigateAck)
return nil
}
func (h *receivedPacketHandler) ReceivedStopWaiting(f *frames.StopWaitingFrame) error {
// ignore if StopWaiting is unneeded, because we already received a StopWaiting with a higher LeastUnacked
if h.ignorePacketsBelow >= f.LeastUnacked {
return nil
}
h.ignorePacketsBelow = f.LeastUnacked - 1
h.packetHistory.DeleteBelow(f.LeastUnacked)
return nil
}
func (h *receivedPacketHandler) maybeQueueAck(packetNumber protocol.PacketNumber, shouldInstigateAck bool) {
var ackAlarmSet bool
h.packetsReceivedSinceLastAck++
if shouldInstigateAck {
h.retransmittablePacketsReceivedSinceLastAck++
}
// always ack the first packet
if h.lastAck == nil {
h.ackQueued = true
}
// Always send an ack every 20 packets in order to allow the peer to discard
// information from the SentPacketManager and provide an RTT measurement.
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().FirstPacketNumber > 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)
ackAlarmSet = true
}
}
}
if h.ackQueued {
// cancel the ack alarm
h.ackAlarm = time.Time{}
ackAlarmSet = false
}
if ackAlarmSet {
h.ackAlarmResetCallback(h.ackAlarm)
}
}
func (h *receivedPacketHandler) GetAckFrame() *frames.AckFrame {
if !h.ackQueued && (h.ackAlarm.IsZero() || h.ackAlarm.After(time.Now())) {
return nil
}
ackRanges := h.packetHistory.GetAckRanges()
ack := &frames.AckFrame{
LargestAcked: h.largestObserved,
LowestAcked: ackRanges[len(ackRanges)-1].FirstPacketNumber,
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
}