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
|
// Copyright 2009 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// UDP for Plan 9
package net
import (
"errors"
"os"
)
// UDPConn is the implementation of the Conn and PacketConn
// interfaces for UDP network connections.
type UDPConn struct {
plan9Conn
}
// UDP-specific methods.
// ReadFromUDP reads a UDP packet from c, copying the payload into b.
// It returns the number of bytes copied into b and the return address
// that was on the packet.
//
// ReadFromUDP can be made to time out and return an error with Timeout() == true
// after a fixed time limit; see SetTimeout and SetReadTimeout.
func (c *UDPConn) ReadFromUDP(b []byte) (n int, addr *UDPAddr, err error) {
if !c.ok() {
return 0, nil, os.EINVAL
}
if c.data == nil {
c.data, err = os.OpenFile(c.dir+"/data", os.O_RDWR, 0)
if err != nil {
return 0, nil, err
}
}
buf := make([]byte, udpHeaderSize+len(b))
m, err := c.data.Read(buf)
if err != nil {
return
}
if m < udpHeaderSize {
return 0, nil, errors.New("short read reading UDP header")
}
buf = buf[:m]
h, buf := unmarshalUDPHeader(buf)
n = copy(b, buf)
return n, &UDPAddr{h.raddr, int(h.rport)}, nil
}
// ReadFrom implements the net.PacketConn ReadFrom method.
func (c *UDPConn) ReadFrom(b []byte) (n int, addr Addr, err error) {
if !c.ok() {
return 0, nil, os.EINVAL
}
return c.ReadFromUDP(b)
}
// WriteToUDP writes a UDP packet to addr via c, copying the payload from b.
//
// WriteToUDP can be made to time out and return
// an error with Timeout() == true after a fixed time limit;
// see SetTimeout and SetWriteTimeout.
// On packet-oriented connections, write timeouts are rare.
func (c *UDPConn) WriteToUDP(b []byte, addr *UDPAddr) (n int, err error) {
if !c.ok() {
return 0, os.EINVAL
}
if c.data == nil {
c.data, err = os.OpenFile(c.dir+"/data", os.O_RDWR, 0)
if err != nil {
return 0, err
}
}
h := new(udpHeader)
h.raddr = addr.IP.To16()
h.laddr = c.laddr.(*UDPAddr).IP.To16()
h.ifcaddr = IPv6zero // ignored (receive only)
h.rport = uint16(addr.Port)
h.lport = uint16(c.laddr.(*UDPAddr).Port)
buf := make([]byte, udpHeaderSize+len(b))
i := copy(buf, h.Bytes())
copy(buf[i:], b)
return c.data.Write(buf)
}
// WriteTo implements the net.PacketConn WriteTo method.
func (c *UDPConn) WriteTo(b []byte, addr Addr) (n int, err error) {
if !c.ok() {
return 0, os.EINVAL
}
a, ok := addr.(*UDPAddr)
if !ok {
return 0, &OpError{"writeto", "udp", addr, os.EINVAL}
}
return c.WriteToUDP(b, a)
}
// DialUDP connects to the remote address raddr on the network net,
// which must be "udp", "udp4", or "udp6". If laddr is not nil, it is used
// as the local address for the connection.
func DialUDP(net string, laddr, raddr *UDPAddr) (c *UDPConn, err error) {
switch net {
case "udp", "udp4", "udp6":
default:
return nil, UnknownNetworkError(net)
}
if raddr == nil {
return nil, &OpError{"dial", "udp", nil, errMissingAddress}
}
c1, err := dialPlan9(net, laddr, raddr)
if err != nil {
return
}
return &UDPConn{*c1}, nil
}
const udpHeaderSize = 16*3 + 2*2
type udpHeader struct {
raddr, laddr, ifcaddr IP
rport, lport uint16
}
func (h *udpHeader) Bytes() []byte {
b := make([]byte, udpHeaderSize)
i := 0
i += copy(b[i:i+16], h.raddr)
i += copy(b[i:i+16], h.laddr)
i += copy(b[i:i+16], h.ifcaddr)
b[i], b[i+1], i = byte(h.rport>>8), byte(h.rport), i+2
b[i], b[i+1], i = byte(h.lport>>8), byte(h.lport), i+2
return b
}
func unmarshalUDPHeader(b []byte) (*udpHeader, []byte) {
h := new(udpHeader)
h.raddr, b = IP(b[:16]), b[16:]
h.laddr, b = IP(b[:16]), b[16:]
h.ifcaddr, b = IP(b[:16]), b[16:]
h.rport, b = uint16(b[0])<<8|uint16(b[1]), b[2:]
h.lport, b = uint16(b[0])<<8|uint16(b[1]), b[2:]
return h, b
}
// ListenUDP listens for incoming UDP packets addressed to the
// local address laddr. The returned connection c's ReadFrom
// and WriteTo methods can be used to receive and send UDP
// packets with per-packet addressing.
func ListenUDP(net string, laddr *UDPAddr) (c *UDPConn, err error) {
switch net {
case "udp", "udp4", "udp6":
default:
return nil, UnknownNetworkError(net)
}
if laddr == nil {
return nil, &OpError{"listen", "udp", nil, errMissingAddress}
}
l, err := listenPlan9(net, laddr)
if err != nil {
return
}
_, err = l.ctl.WriteString("headers")
if err != nil {
return
}
return &UDPConn{*l.plan9Conn()}, nil
}
// JoinGroup joins the IP multicast group named by addr on ifi,
// which specifies the interface to join. JoinGroup uses the
// default multicast interface if ifi is nil.
func (c *UDPConn) JoinGroup(ifi *Interface, addr IP) error {
if !c.ok() {
return os.EINVAL
}
return os.EPLAN9
}
// LeaveGroup exits the IP multicast group named by addr on ifi.
func (c *UDPConn) LeaveGroup(ifi *Interface, addr IP) error {
if !c.ok() {
return os.EINVAL
}
return os.EPLAN9
}
|