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, addr *UDPAddr) (int, *UDPAddr, 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	*addr = UDPAddr{IP: h.raddr, Port: int(h.rport)}
28	return n, addr, nil
29}
30
31func (c *UDPConn) readMsg(b, oob []byte) (n, oobn, flags int, addr *UDPAddr, err error) {
32	return 0, 0, 0, nil, syscall.EPLAN9
33}
34
35func (c *UDPConn) writeTo(b []byte, addr *UDPAddr) (int, error) {
36	if addr == nil {
37		return 0, errMissingAddress
38	}
39	h := new(udpHeader)
40	h.raddr = addr.IP.To16()
41	h.laddr = c.fd.laddr.(*UDPAddr).IP.To16()
42	h.ifcaddr = IPv6zero // ignored (receive only)
43	h.rport = uint16(addr.Port)
44	h.lport = uint16(c.fd.laddr.(*UDPAddr).Port)
45
46	buf := make([]byte, udpHeaderSize+len(b))
47	i := copy(buf, h.Bytes())
48	copy(buf[i:], b)
49	if _, err := c.fd.Write(buf); err != nil {
50		return 0, err
51	}
52	return len(b), nil
53}
54
55func (c *UDPConn) writeMsg(b, oob []byte, addr *UDPAddr) (n, oobn int, err error) {
56	return 0, 0, syscall.EPLAN9
57}
58
59func (sd *sysDialer) dialUDP(ctx context.Context, laddr, raddr *UDPAddr) (*UDPConn, error) {
60	fd, err := dialPlan9(ctx, sd.network, laddr, raddr)
61	if err != nil {
62		return nil, err
63	}
64	return newUDPConn(fd), nil
65}
66
67const udpHeaderSize = 16*3 + 2*2
68
69type udpHeader struct {
70	raddr, laddr, ifcaddr IP
71	rport, lport          uint16
72}
73
74func (h *udpHeader) Bytes() []byte {
75	b := make([]byte, udpHeaderSize)
76	i := 0
77	i += copy(b[i:i+16], h.raddr)
78	i += copy(b[i:i+16], h.laddr)
79	i += copy(b[i:i+16], h.ifcaddr)
80	b[i], b[i+1], i = byte(h.rport>>8), byte(h.rport), i+2
81	b[i], b[i+1], i = byte(h.lport>>8), byte(h.lport), i+2
82	return b
83}
84
85func unmarshalUDPHeader(b []byte) (*udpHeader, []byte) {
86	h := new(udpHeader)
87	h.raddr, b = IP(b[:16]), b[16:]
88	h.laddr, b = IP(b[:16]), b[16:]
89	h.ifcaddr, b = IP(b[:16]), b[16:]
90	h.rport, b = uint16(b[0])<<8|uint16(b[1]), b[2:]
91	h.lport, b = uint16(b[0])<<8|uint16(b[1]), b[2:]
92	return h, b
93}
94
95func (sl *sysListener) listenUDP(ctx context.Context, laddr *UDPAddr) (*UDPConn, error) {
96	l, err := listenPlan9(ctx, sl.network, laddr)
97	if err != nil {
98		return nil, err
99	}
100	_, err = l.ctl.WriteString("headers")
101	if err != nil {
102		return nil, err
103	}
104	l.data, err = os.OpenFile(l.dir+"/data", os.O_RDWR, 0)
105	if err != nil {
106		return nil, err
107	}
108	fd, err := l.netFD()
109	return newUDPConn(fd), err
110}
111
112func (sl *sysListener) listenMulticastUDP(ctx context.Context, ifi *Interface, gaddr *UDPAddr) (*UDPConn, error) {
113	// Plan 9 does not like announce command with a multicast address,
114	// so do not specify an IP address when listening.
115	l, err := listenPlan9(ctx, sl.network, &UDPAddr{IP: nil, Port: gaddr.Port, Zone: gaddr.Zone})
116	if err != nil {
117		return nil, err
118	}
119	_, err = l.ctl.WriteString("headers")
120	if err != nil {
121		return nil, err
122	}
123	var addrs []Addr
124	if ifi != nil {
125		addrs, err = ifi.Addrs()
126		if err != nil {
127			return nil, err
128		}
129	} else {
130		addrs, err = InterfaceAddrs()
131		if err != nil {
132			return nil, err
133		}
134	}
135
136	have4 := gaddr.IP.To4() != nil
137	for _, addr := range addrs {
138		if ipnet, ok := addr.(*IPNet); ok && (ipnet.IP.To4() != nil) == have4 {
139			_, err = l.ctl.WriteString("addmulti " + ipnet.IP.String() + " " + gaddr.IP.String())
140			if err != nil {
141				return nil, &OpError{Op: "addmulti", Net: "", Source: nil, Addr: ipnet, Err: err}
142			}
143		}
144	}
145	l.data, err = os.OpenFile(l.dir+"/data", os.O_RDWR, 0)
146	if err != nil {
147		return nil, err
148	}
149	fd, err := l.netFD()
150	if err != nil {
151		return nil, err
152	}
153	return newUDPConn(fd), nil
154}
155