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
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
|
/* SPDX-License-Identifier: MIT
*
* Copyright (C) 2017-2021 WireGuard LLC. All Rights Reserved.
*/
package conn
import (
"errors"
"net"
"net/netip"
"sync"
"syscall"
)
// StdNetBind is meant to be a temporary solution on platforms for which
// the sticky socket / source caching behavior has not yet been implemented.
// It uses the Go's net package to implement networking.
// See LinuxSocketBind for a proper implementation on the Linux platform.
type StdNetBind struct {
mu sync.Mutex // protects following fields
ipv4 *net.UDPConn
ipv6 *net.UDPConn
blackhole4 bool
blackhole6 bool
}
func NewStdNetBind() Bind { return &StdNetBind{} }
type StdNetEndpoint netip.AddrPort
var _ Bind = (*StdNetBind)(nil)
var _ Endpoint = (*StdNetEndpoint)(nil)
func (*StdNetBind) ParseEndpoint(s string) (Endpoint, error) {
e, err := netip.ParseAddrPort(s)
return (*StdNetEndpoint)(&e), err
}
func (*StdNetEndpoint) ClearSrc() {}
func (e *StdNetEndpoint) DstIP() netip.Addr {
return (*netip.AddrPort)(e).Addr()
}
func (e *StdNetEndpoint) SrcIP() netip.Addr {
return netip.Addr{} // not supported
}
func (e *StdNetEndpoint) DstToBytes() []byte {
addr := (*netip.AddrPort)(e)
out := addr.Addr().AsSlice()
out = append(out, byte(addr.Port()&0xff))
out = append(out, byte((addr.Port()>>8)&0xff))
return out
}
func (e *StdNetEndpoint) DstToString() string {
return (*netip.AddrPort)(e).String()
}
func (e *StdNetEndpoint) SrcToString() string {
return ""
}
func listenNet(network string, port int) (*net.UDPConn, int, error) {
conn, err := net.ListenUDP(network, &net.UDPAddr{Port: port})
if err != nil {
return nil, 0, err
}
// Retrieve port.
laddr := conn.LocalAddr()
uaddr, err := net.ResolveUDPAddr(
laddr.Network(),
laddr.String(),
)
if err != nil {
return nil, 0, err
}
return conn, uaddr.Port, nil
}
func (bind *StdNetBind) Open(uport uint16) ([]ReceiveFunc, uint16, error) {
bind.mu.Lock()
defer bind.mu.Unlock()
var err error
var tries int
if bind.ipv4 != nil || bind.ipv6 != nil {
return nil, 0, ErrBindAlreadyOpen
}
// Attempt to open ipv4 and ipv6 listeners on the same port.
// If uport is 0, we can retry on failure.
again:
port := int(uport)
var ipv4, ipv6 *net.UDPConn
ipv4, port, err = listenNet("udp4", port)
if err != nil && !errors.Is(err, syscall.EAFNOSUPPORT) {
return nil, 0, err
}
// Listen on the same port as we're using for ipv4.
ipv6, port, err = listenNet("udp6", port)
if uport == 0 && errors.Is(err, syscall.EADDRINUSE) && tries < 100 {
ipv4.Close()
tries++
goto again
}
if err != nil && !errors.Is(err, syscall.EAFNOSUPPORT) {
ipv4.Close()
return nil, 0, err
}
var fns []ReceiveFunc
if ipv4 != nil {
fns = append(fns, bind.makeReceiveIPv4(ipv4))
bind.ipv4 = ipv4
}
if ipv6 != nil {
fns = append(fns, bind.makeReceiveIPv6(ipv6))
bind.ipv6 = ipv6
}
if len(fns) == 0 {
return nil, 0, syscall.EAFNOSUPPORT
}
return fns, uint16(port), nil
}
func (bind *StdNetBind) Close() error {
bind.mu.Lock()
defer bind.mu.Unlock()
var err1, err2 error
if bind.ipv4 != nil {
err1 = bind.ipv4.Close()
bind.ipv4 = nil
}
if bind.ipv6 != nil {
err2 = bind.ipv6.Close()
bind.ipv6 = nil
}
bind.blackhole4 = false
bind.blackhole6 = false
if err1 != nil {
return err1
}
return err2
}
func (*StdNetBind) makeReceiveIPv4(conn *net.UDPConn) ReceiveFunc {
return func(buff []byte) (int, Endpoint, error) {
n, endpoint, err := conn.ReadFromUDPAddrPort(buff)
return n, (*StdNetEndpoint)(&endpoint), err
}
}
func (*StdNetBind) makeReceiveIPv6(conn *net.UDPConn) ReceiveFunc {
return func(buff []byte) (int, Endpoint, error) {
n, endpoint, err := conn.ReadFromUDPAddrPort(buff)
return n, (*StdNetEndpoint)(&endpoint), err
}
}
func (bind *StdNetBind) Send(buff []byte, endpoint Endpoint) error {
var err error
nend, ok := endpoint.(*StdNetEndpoint)
if !ok {
return ErrWrongEndpointType
}
addr := (*netip.AddrPort)(nend)
bind.mu.Lock()
var (
blackhole bool
conn *net.UDPConn
)
if addr.Addr().Is4() {
blackhole = bind.blackhole4
conn = bind.ipv4
} else if addr.Addr().Is6() {
blackhole = bind.blackhole6
conn = bind.ipv6
}
bind.mu.Unlock()
if blackhole {
return nil
}
if conn == nil {
return syscall.EAFNOSUPPORT
}
_, err = conn.WriteToUDPAddrPort(buff, *addr)
return err
}
|
