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
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
|
package rudp
import (
"errors"
"net"
"sync"
)
func tryClose(ch chan struct{}) (ok bool) {
defer func() { recover() }()
close(ch)
return true
}
type udpClt struct {
l *Listener
id PeerID
addr net.Addr
pkts chan []byte
closed chan struct{}
}
func (c *udpClt) mkConn() {
conn := newConn(c, c.id, PeerIDSrv)
go func() {
<-conn.Closed()
c.l.wg.Done()
}()
conn.sendRaw(func(buf []byte) int {
buf[0] = uint8(rawCtl)
buf[1] = uint8(ctlSetPeerID)
be.PutUint16(buf[2:4], uint16(conn.ID()))
return 4
}, PktInfo{})()
select {
case c.l.conns <- conn:
case <-c.l.closed:
conn.Close()
}
}
func (c *udpClt) Write(pkt []byte) (int, error) {
select {
case <-c.closed:
return 0, net.ErrClosed
default:
}
return c.l.pc.WriteTo(pkt, c.addr)
}
func (c *udpClt) recvUDP() ([]byte, error) {
select {
case pkt := <-c.pkts:
return pkt, nil
case <-c.closed:
return nil, net.ErrClosed
}
}
func (c *udpClt) Close() error {
if !tryClose(c.closed) {
return net.ErrClosed
}
c.l.mu.Lock()
defer c.l.mu.Unlock()
delete(c.l.ids, c.id)
delete(c.l.clts, c.addr.String())
return nil
}
func (c *udpClt) LocalAddr() net.Addr { return c.l.pc.LocalAddr() }
func (c *udpClt) RemoteAddr() net.Addr { return c.addr }
// All Listener's methods are safe for concurrent use.
type Listener struct {
pc net.PacketConn
peerID PeerID
conns chan *Conn
errs chan error
closed chan struct{}
wg sync.WaitGroup
mu sync.RWMutex
ids map[PeerID]bool
clts map[string]*udpClt
}
// Listen listens for connections on pc, pc is closed once the returned Listener
// and all Conns connected through it are closed.
func Listen(pc net.PacketConn) *Listener {
l := &Listener{
pc: pc,
conns: make(chan *Conn),
closed: make(chan struct{}),
ids: make(map[PeerID]bool),
clts: make(map[string]*udpClt),
}
go func() {
for {
if err := l.processNetPkt(); err != nil {
if errors.Is(err, net.ErrClosed) {
break
}
select {
case l.errs <- err:
case <-l.closed:
}
}
}
}()
return l
}
// Accept waits for and returns the next incoming Conn or an error.
func (l *Listener) Accept() (*Conn, error) {
select {
case c := <-l.conns:
return c, nil
case err := <-l.errs:
return nil, err
case <-l.closed:
return nil, net.ErrClosed
}
}
// Close makes the Listener stop listening for new Conns.
// Blocked Accept calls will return net.ErrClosed.
// Already Accepted Conns are not closed.
func (l *Listener) Close() error {
if !tryClose(l.closed) {
return net.ErrClosed
}
go func() {
l.wg.Wait()
l.pc.Close()
}()
return nil
}
// Addr returns the Listener's network address.
func (l *Listener) Addr() net.Addr { return l.pc.LocalAddr() }
var ErrOutOfPeerIDs = errors.New("out of peer ids")
func (l *Listener) processNetPkt() error {
buf := make([]byte, maxUDPPktSize)
n, addr, err := l.pc.ReadFrom(buf)
if err != nil {
return err
}
l.mu.RLock()
clt, ok := l.clts[addr.String()]
l.mu.RUnlock()
if !ok {
select {
case <-l.closed:
return nil
default:
}
clt, err = l.add(addr)
if err != nil {
return err
}
}
select {
case clt.pkts <- buf[:n]:
case <-clt.closed:
}
return nil
}
func (l *Listener) add(addr net.Addr) (*udpClt, error) {
l.mu.Lock()
defer l.mu.Unlock()
start := l.peerID
l.peerID++
for l.peerID < PeerIDCltMin || l.ids[l.peerID] {
if l.peerID == start {
return nil, ErrOutOfPeerIDs
}
l.peerID++
}
l.ids[l.peerID] = true
clt := &udpClt{
l: l,
id: l.peerID,
addr: addr,
pkts: make(chan []byte),
closed: make(chan struct{}),
}
l.clts[addr.String()] = clt
l.wg.Add(1)
go clt.mkConn()
return clt, nil
}
|
