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// Copyright 2023 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.
//go:build js || wasip1
package net
import (
"internal/poll"
"runtime"
"time"
)
const (
readSyscallName = "fd_read"
writeSyscallName = "fd_write"
)
// Network file descriptor.
type netFD struct {
pfd poll.FD
// immutable until Close
family int
sotype int
isConnected bool // handshake completed or use of association with peer
net string
laddr Addr
raddr Addr
// The only networking available in WASI preview 1 is the ability to
// sock_accept on a pre-opened socket, and then fd_read, fd_write,
// fd_close, and sock_shutdown on the resulting connection. We
// intercept applicable netFD calls on this instance, and then pass
// the remainder of the netFD calls to fakeNetFD.
*fakeNetFD
}
func newFD(net string, sysfd int) *netFD {
return newPollFD(net, poll.FD{
Sysfd: sysfd,
IsStream: true,
ZeroReadIsEOF: true,
})
}
func newPollFD(net string, pfd poll.FD) *netFD {
var laddr Addr
var raddr Addr
// WASI preview 1 does not have functions like getsockname/getpeername,
// so we cannot get access to the underlying IP address used by connections.
//
// However, listeners created by FileListener are of type *TCPListener,
// which can be asserted by a Go program. The (*TCPListener).Addr method
// documents that the returned value will be of type *TCPAddr, we satisfy
// the documented behavior by creating addresses of the expected type here.
switch net {
case "tcp":
laddr = new(TCPAddr)
raddr = new(TCPAddr)
case "udp":
laddr = new(UDPAddr)
raddr = new(UDPAddr)
default:
laddr = unknownAddr{}
raddr = unknownAddr{}
}
return &netFD{
pfd: pfd,
net: net,
laddr: laddr,
raddr: raddr,
}
}
func (fd *netFD) init() error {
return fd.pfd.Init(fd.net, true)
}
func (fd *netFD) name() string {
return "unknown"
}
func (fd *netFD) accept() (netfd *netFD, err error) {
if fd.fakeNetFD != nil {
return fd.fakeNetFD.accept(fd.laddr)
}
d, _, errcall, err := fd.pfd.Accept()
if err != nil {
if errcall != "" {
err = wrapSyscallError(errcall, err)
}
return nil, err
}
netfd = newFD("tcp", d)
if err = netfd.init(); err != nil {
netfd.Close()
return nil, err
}
return netfd, nil
}
func (fd *netFD) setAddr(laddr, raddr Addr) {
fd.laddr = laddr
fd.raddr = raddr
runtime.SetFinalizer(fd, (*netFD).Close)
}
func (fd *netFD) Close() error {
if fd.fakeNetFD != nil {
return fd.fakeNetFD.Close()
}
runtime.SetFinalizer(fd, nil)
return fd.pfd.Close()
}
func (fd *netFD) shutdown(how int) error {
if fd.fakeNetFD != nil {
return nil
}
err := fd.pfd.Shutdown(how)
runtime.KeepAlive(fd)
return wrapSyscallError("shutdown", err)
}
func (fd *netFD) Read(p []byte) (n int, err error) {
if fd.fakeNetFD != nil {
return fd.fakeNetFD.Read(p)
}
n, err = fd.pfd.Read(p)
runtime.KeepAlive(fd)
return n, wrapSyscallError(readSyscallName, err)
}
func (fd *netFD) Write(p []byte) (nn int, err error) {
if fd.fakeNetFD != nil {
return fd.fakeNetFD.Write(p)
}
nn, err = fd.pfd.Write(p)
runtime.KeepAlive(fd)
return nn, wrapSyscallError(writeSyscallName, err)
}
func (fd *netFD) SetDeadline(t time.Time) error {
if fd.fakeNetFD != nil {
return fd.fakeNetFD.SetDeadline(t)
}
return fd.pfd.SetDeadline(t)
}
func (fd *netFD) SetReadDeadline(t time.Time) error {
if fd.fakeNetFD != nil {
return fd.fakeNetFD.SetReadDeadline(t)
}
return fd.pfd.SetReadDeadline(t)
}
func (fd *netFD) SetWriteDeadline(t time.Time) error {
if fd.fakeNetFD != nil {
return fd.fakeNetFD.SetWriteDeadline(t)
}
return fd.pfd.SetWriteDeadline(t)
}
type unknownAddr struct{}
func (unknownAddr) Network() string { return "unknown" }
func (unknownAddr) String() string { return "unknown" }
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