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
167
168
169
170
171
172
173
174
175
176
177
178
179
|
// Copyright 2020 The gVisor Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package stack
import (
"fmt"
"gvisor.dev/gvisor/pkg/sync"
"gvisor.dev/gvisor/pkg/tcpip"
)
const (
// maxPendingResolutions is the maximum number of pending link-address
// resolutions.
maxPendingResolutions = 64
maxPendingPacketsPerResolution = 256
)
// pendingPacketBuffer is a pending packet buffer.
//
// TODO(gvisor.dev/issue/5331): Drop this when we drop WritePacket and only use
// WritePackets so we can use a PacketBufferList everywhere.
type pendingPacketBuffer interface {
len() int
}
func (*PacketBuffer) len() int {
return 1
}
func (p *PacketBufferList) len() int {
return p.Len()
}
type pendingPacket struct {
route *Route
proto tcpip.NetworkProtocolNumber
pkt pendingPacketBuffer
}
// packetsPendingLinkResolution is a queue of packets pending link resolution.
//
// Once link resolution completes successfully, the packets will be written.
type packetsPendingLinkResolution struct {
sync.Mutex
// The packets to send once the resolver completes.
packets map[<-chan struct{}][]pendingPacket
// FIFO of channels used to cancel the oldest goroutine waiting for
// link-address resolution.
cancelChans []chan struct{}
}
func (f *packetsPendingLinkResolution) init() {
f.Lock()
defer f.Unlock()
f.packets = make(map[<-chan struct{}][]pendingPacket)
}
func incrementOutgoingPacketErrors(r *Route, proto tcpip.NetworkProtocolNumber, pkt pendingPacketBuffer) {
n := uint64(pkt.len())
r.Stats().IP.OutgoingPacketErrors.IncrementBy(n)
// ok may be false if the endpoint's stats do not collect IP-related data.
if ipEndpointStats, ok := r.outgoingNIC.getNetworkEndpoint(proto).Stats().(IPNetworkEndpointStats); ok {
ipEndpointStats.IPStats().OutgoingPacketErrors.IncrementBy(n)
}
}
func (f *packetsPendingLinkResolution) enqueue(ch <-chan struct{}, r *Route, proto tcpip.NetworkProtocolNumber, pkt pendingPacketBuffer) {
f.Lock()
defer f.Unlock()
packets, ok := f.packets[ch]
if len(packets) == maxPendingPacketsPerResolution {
p := packets[0]
packets[0] = pendingPacket{}
packets = packets[1:]
incrementOutgoingPacketErrors(r, proto, p.pkt)
p.route.Release()
}
if l := len(packets); l >= maxPendingPacketsPerResolution {
panic(fmt.Sprintf("max pending packets for resolution reached; got %d packets, max = %d", l, maxPendingPacketsPerResolution))
}
f.packets[ch] = append(packets, pendingPacket{
route: r,
proto: proto,
pkt: pkt,
})
if ok {
return
}
// Wait for the link-address resolution to complete.
cancel := f.newCancelChannelLocked()
go func() {
cancelled := false
select {
case <-ch:
case <-cancel:
cancelled = true
}
f.Lock()
packets, ok := f.packets[ch]
delete(f.packets, ch)
f.Unlock()
if !ok {
panic(fmt.Sprintf("link-resolution goroutine woke up but no entry exists in the queue of packets"))
}
for _, p := range packets {
if cancelled || p.route.IsResolutionRequired() {
incrementOutgoingPacketErrors(r, proto, p.pkt)
if linkResolvableEP, ok := p.route.outgoingNIC.getNetworkEndpoint(p.route.NetProto).(LinkResolvableNetworkEndpoint); ok {
switch pkt := p.pkt.(type) {
case *PacketBuffer:
linkResolvableEP.HandleLinkResolutionFailure(pkt)
case *PacketBufferList:
for pb := pkt.Front(); pb != nil; pb = pb.Next() {
linkResolvableEP.HandleLinkResolutionFailure(pb)
}
default:
panic(fmt.Sprintf("unrecognized pending packet buffer type = %T", p.pkt))
}
}
} else {
switch pkt := p.pkt.(type) {
case *PacketBuffer:
p.route.outgoingNIC.writePacket(p.route.Fields(), nil /* gso */, p.proto, pkt)
case *PacketBufferList:
p.route.outgoingNIC.writePackets(p.route.Fields(), nil /* gso */, p.proto, *pkt)
default:
panic(fmt.Sprintf("unrecognized pending packet buffer type = %T", p.pkt))
}
}
p.route.Release()
}
}()
}
// newCancelChannel creates a channel that can cancel a pending forwarding
// activity. The oldest channel is closed if the number of open channels would
// exceed maxPendingResolutions.
func (f *packetsPendingLinkResolution) newCancelChannelLocked() chan struct{} {
if len(f.cancelChans) == maxPendingResolutions {
ch := f.cancelChans[0]
f.cancelChans[0] = nil
f.cancelChans = f.cancelChans[1:]
close(ch)
}
if l := len(f.cancelChans); l >= maxPendingResolutions {
panic(fmt.Sprintf("max pending resolutions reached; got %d active resolutions, max = %d", l, maxPendingResolutions))
}
ch := make(chan struct{})
f.cancelChans = append(f.cancelChans, ch)
return ch
}
|
