1// Copyright 2023 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
5//go:build js || wasip1
6
7package net
8
9import (
10	"internal/poll"
11	"runtime"
12	"time"
13)
14
15const (
16	readSyscallName  = "fd_read"
17	writeSyscallName = "fd_write"
18)
19
20// Network file descriptor.
21type netFD struct {
22	pfd poll.FD
23
24	// immutable until Close
25	family      int
26	sotype      int
27	isConnected bool // handshake completed or use of association with peer
28	net         string
29	laddr       Addr
30	raddr       Addr
31
32	// The only networking available in WASI preview 1 is the ability to
33	// sock_accept on a pre-opened socket, and then fd_read, fd_write,
34	// fd_close, and sock_shutdown on the resulting connection. We
35	// intercept applicable netFD calls on this instance, and then pass
36	// the remainder of the netFD calls to fakeNetFD.
37	*fakeNetFD
38}
39
40func newFD(net string, sysfd int) *netFD {
41	return newPollFD(net, poll.FD{
42		Sysfd:         sysfd,
43		IsStream:      true,
44		ZeroReadIsEOF: true,
45	})
46}
47
48func newPollFD(net string, pfd poll.FD) *netFD {
49	var laddr Addr
50	var raddr Addr
51	// WASI preview 1 does not have functions like getsockname/getpeername,
52	// so we cannot get access to the underlying IP address used by connections.
53	//
54	// However, listeners created by FileListener are of type *TCPListener,
55	// which can be asserted by a Go program. The (*TCPListener).Addr method
56	// documents that the returned value will be of type *TCPAddr, we satisfy
57	// the documented behavior by creating addresses of the expected type here.
58	switch net {
59	case "tcp":
60		laddr = new(TCPAddr)
61		raddr = new(TCPAddr)
62	case "udp":
63		laddr = new(UDPAddr)
64		raddr = new(UDPAddr)
65	default:
66		laddr = unknownAddr{}
67		raddr = unknownAddr{}
68	}
69	return &netFD{
70		pfd:   pfd,
71		net:   net,
72		laddr: laddr,
73		raddr: raddr,
74	}
75}
76
77func (fd *netFD) init() error {
78	return fd.pfd.Init(fd.net, true)
79}
80
81func (fd *netFD) name() string {
82	return "unknown"
83}
84
85func (fd *netFD) accept() (netfd *netFD, err error) {
86	if fd.fakeNetFD != nil {
87		return fd.fakeNetFD.accept(fd.laddr)
88	}
89	d, _, errcall, err := fd.pfd.Accept()
90	if err != nil {
91		if errcall != "" {
92			err = wrapSyscallError(errcall, err)
93		}
94		return nil, err
95	}
96	netfd = newFD("tcp", d)
97	if err = netfd.init(); err != nil {
98		netfd.Close()
99		return nil, err
100	}
101	return netfd, nil
102}
103
104func (fd *netFD) setAddr(laddr, raddr Addr) {
105	fd.laddr = laddr
106	fd.raddr = raddr
107	runtime.SetFinalizer(fd, (*netFD).Close)
108}
109
110func (fd *netFD) Close() error {
111	if fd.fakeNetFD != nil {
112		return fd.fakeNetFD.Close()
113	}
114	runtime.SetFinalizer(fd, nil)
115	return fd.pfd.Close()
116}
117
118func (fd *netFD) shutdown(how int) error {
119	if fd.fakeNetFD != nil {
120		return nil
121	}
122	err := fd.pfd.Shutdown(how)
123	runtime.KeepAlive(fd)
124	return wrapSyscallError("shutdown", err)
125}
126
127func (fd *netFD) Read(p []byte) (n int, err error) {
128	if fd.fakeNetFD != nil {
129		return fd.fakeNetFD.Read(p)
130	}
131	n, err = fd.pfd.Read(p)
132	runtime.KeepAlive(fd)
133	return n, wrapSyscallError(readSyscallName, err)
134}
135
136func (fd *netFD) Write(p []byte) (nn int, err error) {
137	if fd.fakeNetFD != nil {
138		return fd.fakeNetFD.Write(p)
139	}
140	nn, err = fd.pfd.Write(p)
141	runtime.KeepAlive(fd)
142	return nn, wrapSyscallError(writeSyscallName, err)
143}
144
145func (fd *netFD) SetDeadline(t time.Time) error {
146	if fd.fakeNetFD != nil {
147		return fd.fakeNetFD.SetDeadline(t)
148	}
149	return fd.pfd.SetDeadline(t)
150}
151
152func (fd *netFD) SetReadDeadline(t time.Time) error {
153	if fd.fakeNetFD != nil {
154		return fd.fakeNetFD.SetReadDeadline(t)
155	}
156	return fd.pfd.SetReadDeadline(t)
157}
158
159func (fd *netFD) SetWriteDeadline(t time.Time) error {
160	if fd.fakeNetFD != nil {
161		return fd.fakeNetFD.SetWriteDeadline(t)
162	}
163	return fd.pfd.SetWriteDeadline(t)
164}
165
166type unknownAddr struct{}
167
168func (unknownAddr) Network() string { return "unknown" }
169func (unknownAddr) String() string  { return "unknown" }
170