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
|
// Copyright 2018 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 waitable provides the implementation of data-link layer endpoints
// that wrap other endpoints, and can wait for inflight calls to WritePacket or
// DeliverNetworkPacket to finish (and new ones to be prevented).
//
// Waitable endpoints can be used in the networking stack by calling New(eID) to
// create a new endpoint, where eID is the ID of the endpoint being wrapped,
// and then passing it as an argument to Stack.CreateNIC().
package waitable
import (
"gvisor.dev/gvisor/pkg/gate"
"gvisor.dev/gvisor/pkg/tcpip"
"gvisor.dev/gvisor/pkg/tcpip/buffer"
"gvisor.dev/gvisor/pkg/tcpip/header"
"gvisor.dev/gvisor/pkg/tcpip/stack"
)
// Endpoint is a waitable link-layer endpoint.
type Endpoint struct {
dispatchGate gate.Gate
dispatcher stack.NetworkDispatcher
writeGate gate.Gate
lower stack.LinkEndpoint
}
// New creates a new waitable link-layer endpoint. It wraps around another
// endpoint and allows the caller to block new write/dispatch calls and wait for
// the inflight ones to finish before returning.
func New(lower stack.LinkEndpoint) *Endpoint {
return &Endpoint{
lower: lower,
}
}
// DeliverNetworkPacket implements stack.NetworkDispatcher.DeliverNetworkPacket.
// It is called by the link-layer endpoint being wrapped when a packet arrives,
// and only forwards to the actual dispatcher if Wait or WaitDispatch haven't
// been called.
func (e *Endpoint) DeliverNetworkPacket(remote, local tcpip.LinkAddress, protocol tcpip.NetworkProtocolNumber, pkt *stack.PacketBuffer) {
if !e.dispatchGate.Enter() {
return
}
e.dispatcher.DeliverNetworkPacket(remote, local, protocol, pkt)
e.dispatchGate.Leave()
}
// Attach implements stack.LinkEndpoint.Attach. It saves the dispatcher and
// registers with the lower endpoint as its dispatcher so that "e" is called
// for inbound packets.
func (e *Endpoint) Attach(dispatcher stack.NetworkDispatcher) {
e.dispatcher = dispatcher
e.lower.Attach(e)
}
// IsAttached implements stack.LinkEndpoint.IsAttached.
func (e *Endpoint) IsAttached() bool {
return e.dispatcher != nil
}
// MTU implements stack.LinkEndpoint.MTU. It just forwards the request to the
// lower endpoint.
func (e *Endpoint) MTU() uint32 {
return e.lower.MTU()
}
// Capabilities implements stack.LinkEndpoint.Capabilities. It just forwards the
// request to the lower endpoint.
func (e *Endpoint) Capabilities() stack.LinkEndpointCapabilities {
return e.lower.Capabilities()
}
// MaxHeaderLength implements stack.LinkEndpoint.MaxHeaderLength. It just
// forwards the request to the lower endpoint.
func (e *Endpoint) MaxHeaderLength() uint16 {
return e.lower.MaxHeaderLength()
}
// LinkAddress implements stack.LinkEndpoint.LinkAddress. It just forwards the
// request to the lower endpoint.
func (e *Endpoint) LinkAddress() tcpip.LinkAddress {
return e.lower.LinkAddress()
}
// WritePacket implements stack.LinkEndpoint.WritePacket. It is called by
// higher-level protocols to write packets. It only forwards packets to the
// lower endpoint if Wait or WaitWrite haven't been called.
func (e *Endpoint) WritePacket(r *stack.Route, gso *stack.GSO, protocol tcpip.NetworkProtocolNumber, pkt *stack.PacketBuffer) *tcpip.Error {
if !e.writeGate.Enter() {
return nil
}
err := e.lower.WritePacket(r, gso, protocol, pkt)
e.writeGate.Leave()
return err
}
// WritePackets implements stack.LinkEndpoint.WritePackets. It is called by
// higher-level protocols to write packets. It only forwards packets to the
// lower endpoint if Wait or WaitWrite haven't been called.
func (e *Endpoint) WritePackets(r *stack.Route, gso *stack.GSO, pkts stack.PacketBufferList, protocol tcpip.NetworkProtocolNumber) (int, *tcpip.Error) {
if !e.writeGate.Enter() {
return pkts.Len(), nil
}
n, err := e.lower.WritePackets(r, gso, pkts, protocol)
e.writeGate.Leave()
return n, err
}
// WriteRawPacket implements stack.LinkEndpoint.WriteRawPacket.
func (e *Endpoint) WriteRawPacket(vv buffer.VectorisedView) *tcpip.Error {
if !e.writeGate.Enter() {
return nil
}
err := e.lower.WriteRawPacket(vv)
e.writeGate.Leave()
return err
}
// WaitWrite prevents new calls to WritePacket from reaching the lower endpoint,
// and waits for inflight ones to finish before returning.
func (e *Endpoint) WaitWrite() {
e.writeGate.Close()
}
// WaitDispatch prevents new calls to DeliverNetworkPacket from reaching the
// actual dispatcher, and waits for inflight ones to finish before returning.
func (e *Endpoint) WaitDispatch() {
e.dispatchGate.Close()
}
// Wait implements stack.LinkEndpoint.Wait.
func (e *Endpoint) Wait() {}
// ARPHardwareType implements stack.LinkEndpoint.ARPHardwareType.
func (e *Endpoint) ARPHardwareType() header.ARPHardwareType {
return e.lower.ARPHardwareType()
}
|
