1// Copyright 2009 The Go Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style
3// license that can be found in the LICENSE file.
4
5package net
6
7import (
8	"context"
9	"errors"
10	"os"
11	"syscall"
12)
13
14func (c *UDPConn) readFrom(b []byte) (n int, addr *UDPAddr, err error) {
15	buf := make([]byte, udpHeaderSize+len(b))
16	m, err := c.fd.Read(buf)
17	if err != nil {
18		return 0, nil, err
19	}
20	if m < udpHeaderSize {
21		return 0, nil, errors.New("short read reading UDP header")
22	}
23	buf = buf[:m]
24
25	h, buf := unmarshalUDPHeader(buf)
26	n = copy(b, buf)
27	return n, &UDPAddr{IP: h.raddr, Port: int(h.rport)}, nil
28}
29
30func (c *UDPConn) readMsg(b, oob []byte) (n, oobn, flags int, addr *UDPAddr, err error) {
31	return 0, 0, 0, nil, syscall.EPLAN9
32}
33
34func (c *UDPConn) writeTo(b []byte, addr *UDPAddr) (int, error) {
35	if addr == nil {
36		return 0, errMissingAddress
37	}
38	h := new(udpHeader)
39	h.raddr = addr.IP.To16()
40	h.laddr = c.fd.laddr.(*UDPAddr).IP.To16()
41	h.ifcaddr = IPv6zero // ignored (receive only)
42	h.rport = uint16(addr.Port)
43	h.lport = uint16(c.fd.laddr.(*UDPAddr).Port)
44
45	buf := make([]byte, udpHeaderSize+len(b))
46	i := copy(buf, h.Bytes())
47	copy(buf[i:], b)
48	if _, err := c.fd.Write(buf); err != nil {
49		return 0, err
50	}
51	return len(b), nil
52}
53
54func (c *UDPConn) writeMsg(b, oob []byte, addr *UDPAddr) (n, oobn int, err error) {
55	return 0, 0, syscall.EPLAN9
56}
57
58func (sd *sysDialer) dialUDP(ctx context.Context, laddr, raddr *UDPAddr) (*UDPConn, error) {
59	fd, err := dialPlan9(ctx, sd.network, laddr, raddr)
60	if err != nil {
61		return nil, err
62	}
63	return newUDPConn(fd), nil
64}
65
66const udpHeaderSize = 16*3 + 2*2
67
68type udpHeader struct {
69	raddr, laddr, ifcaddr IP
70	rport, lport          uint16
71}
72
73func (h *udpHeader) Bytes() []byte {
74	b := make([]byte, udpHeaderSize)
75	i := 0
76	i += copy(b[i:i+16], h.raddr)
77	i += copy(b[i:i+16], h.laddr)
78	i += copy(b[i:i+16], h.ifcaddr)
79	b[i], b[i+1], i = byte(h.rport>>8), byte(h.rport), i+2
80	b[i], b[i+1], i = byte(h.lport>>8), byte(h.lport), i+2
81	return b
82}
83
84func unmarshalUDPHeader(b []byte) (*udpHeader, []byte) {
85	h := new(udpHeader)
86	h.raddr, b = IP(b[:16]), b[16:]
87	h.laddr, b = IP(b[:16]), b[16:]
88	h.ifcaddr, b = IP(b[:16]), b[16:]
89	h.rport, b = uint16(b[0])<<8|uint16(b[1]), b[2:]
90	h.lport, b = uint16(b[0])<<8|uint16(b[1]), b[2:]
91	return h, b
92}
93
94func (sl *sysListener) listenUDP(ctx context.Context, laddr *UDPAddr) (*UDPConn, error) {
95	l, err := listenPlan9(ctx, sl.network, laddr)
96	if err != nil {
97		return nil, err
98	}
99	_, err = l.ctl.WriteString("headers")
100	if err != nil {
101		return nil, err
102	}
103	l.data, err = os.OpenFile(l.dir+"/data", os.O_RDWR, 0)
104	if err != nil {
105		return nil, err
106	}
107	fd, err := l.netFD()
108	return newUDPConn(fd), err
109}
110
111func (sl *sysListener) listenMulticastUDP(ctx context.Context, ifi *Interface, gaddr *UDPAddr) (*UDPConn, error) {
112	// Plan 9 does not like announce command with a multicast address,
113	// so do not specify an IP address when listening.
114	l, err := listenPlan9(ctx, sl.network, &UDPAddr{IP: nil, Port: gaddr.Port, Zone: gaddr.Zone})
115	if err != nil {
116		return nil, err
117	}
118	_, err = l.ctl.WriteString("headers")
119	if err != nil {
120		return nil, err
121	}
122	var addrs []Addr
123	if ifi != nil {
124		addrs, err = ifi.Addrs()
125		if err != nil {
126			return nil, err
127		}
128	} else {
129		addrs, err = InterfaceAddrs()
130		if err != nil {
131			return nil, err
132		}
133	}
134
135	have4 := gaddr.IP.To4() != nil
136	for _, addr := range addrs {
137		if ipnet, ok := addr.(*IPNet); ok && (ipnet.IP.To4() != nil) == have4 {
138			_, err = l.ctl.WriteString("addmulti " + ipnet.IP.String() + " " + gaddr.IP.String())
139			if err != nil {
140				return nil, &OpError{Op: "addmulti", Net: "", Source: nil, Addr: ipnet, Err: err}
141			}
142		}
143	}
144	l.data, err = os.OpenFile(l.dir+"/data", os.O_RDWR, 0)
145	if err != nil {
146		return nil, err
147	}
148	fd, err := l.netFD()
149	if err != nil {
150		return nil, err
151	}
152	return newUDPConn(fd), nil
153}
154