net: add js/wasm architecture

This commit adds the js/wasm architecture to the net package.
The net package is not supported by js/wasm, but a simple fake
networking is available so tests of other packages that require
basic TCP sockets can pass. The tests of the net package itself
are mostly disabled.

Updates #18892

Change-Id: Id287200c39f0a3e23d20ef17260ca15ccdcca032
Reviewed-on: https://go-review.googlesource.com/109995
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

src/internal/poll/hook_unix.go

@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// +build darwin dragonfly freebsd linux nacl netbsd openbsd solaris
+// +build darwin dragonfly freebsd js,wasm linux nacl netbsd openbsd solaris
 
 package poll
 

src/net/conn_test.go

@@ -5,6 +5,8 @@
 // This file implements API tests across platforms and will never have a build
 // tag.
 
+// +build !js
+
 package net
 
 import (

src/net/dial_test.go

@@ -2,6 +2,8 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+// +build !js
+
 package net
 
 import (

src/net/dnsname_test.go

@@ -2,6 +2,8 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+// +build !js
+
 package net
 
 import (

src/net/error_posix.go

@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// +build darwin dragonfly freebsd linux nacl netbsd openbsd solaris windows
+// +build darwin dragonfly freebsd js,wasm linux nacl netbsd openbsd solaris windows
 
 package net
 

src/net/error_test.go

@@ -2,6 +2,8 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+// +build !js
+
 package net
 
 import (

src/net/error_unix.go

@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// +build darwin dragonfly freebsd linux netbsd openbsd solaris
+// +build darwin dragonfly freebsd js linux netbsd openbsd solaris
 
 package net
 

src/net/external_test.go

@@ -2,6 +2,8 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+// +build !js
+
 package net
 
 import (

src/net/fd_plan9.go

@@ -9,6 +9,7 @@ import (
 	"io"
 	"os"
 	"syscall"
+	"time"
 )
 
 // Network file descriptor.
@@ -172,3 +173,15 @@ func setReadBuffer(fd *netFD, bytes int) error {
 func setWriteBuffer(fd *netFD, bytes int) error {
 	return syscall.EPLAN9
 }
+
+func (fd *netFD) SetDeadline(t time.Time) error {
+	return fd.pfd.SetDeadline(t)
+}
+
+func (fd *netFD) SetReadDeadline(t time.Time) error {
+	return fd.pfd.SetReadDeadline(t)
+}
+
+func (fd *netFD) SetWriteDeadline(t time.Time) error {
+	return fd.pfd.SetWriteDeadline(t)
+}

src/net/fd_unix.go

@@ -13,6 +13,7 @@ import (
 	"runtime"
 	"sync/atomic"
 	"syscall"
+	"time"
 )
 
 // Network file descriptor.
@@ -298,3 +299,15 @@ func (fd *netFD) dup() (f *os.File, err error) {
 
 	return os.NewFile(uintptr(ns), fd.name()), nil
 }
+
+func (fd *netFD) SetDeadline(t time.Time) error {
+	return fd.pfd.SetDeadline(t)
+}
+
+func (fd *netFD) SetReadDeadline(t time.Time) error {
+	return fd.pfd.SetReadDeadline(t)
+}
+
+func (fd *netFD) SetWriteDeadline(t time.Time) error {
+	return fd.pfd.SetWriteDeadline(t)
+}

src/net/fd_windows.go

@@ -10,6 +10,7 @@ import (
 	"os"
 	"runtime"
 	"syscall"
+	"time"
 	"unsafe"
 )
 
@@ -241,3 +242,15 @@ func (fd *netFD) dup() (*os.File, error) {
 	// TODO: Implement this
 	return nil, syscall.EWINDOWS
 }
+
+func (fd *netFD) SetDeadline(t time.Time) error {
+	return fd.pfd.SetDeadline(t)
+}
+
+func (fd *netFD) SetReadDeadline(t time.Time) error {
+	return fd.pfd.SetReadDeadline(t)
+}
+
+func (fd *netFD) SetWriteDeadline(t time.Time) error {
+	return fd.pfd.SetWriteDeadline(t)
+}

src/net/file_stub.go

@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// +build nacl
+// +build nacl js,wasm
 
 package net
 

src/net/file_test.go

@@ -2,6 +2,8 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+// +build !js
+
 package net
 
 import (

src/net/hook_unix.go

@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// +build darwin dragonfly freebsd linux nacl netbsd openbsd solaris
+// +build darwin dragonfly freebsd js,wasm linux nacl netbsd openbsd solaris
 
 package net
 

src/net/http/cgi/host_test.go

@@ -502,6 +502,7 @@ func TestDirWindows(t *testing.T) {
 }
 
 func TestEnvOverride(t *testing.T) {
+	check(t)
 	cgifile, _ := filepath.Abs("testdata/test.cgi")
 
 	var perl string

src/net/interface_stub.go

@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// +build nacl
+// +build nacl js,wasm
 
 package net
 

src/net/interface_test.go

@@ -2,6 +2,8 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+// +build !js
+
 package net
 
 import (

src/net/internal/socktest/main_test.go

@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// +build !plan9
+// +build !js,!plan9
 
 package socktest_test
 

src/net/internal/socktest/main_unix_test.go

@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// +build !plan9,!windows
+// +build !js,!plan9,!windows
 
 package socktest_test
 

src/net/internal/socktest/switch_unix.go

@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// +build darwin dragonfly freebsd linux nacl netbsd openbsd solaris
+// +build darwin dragonfly freebsd js,wasm linux nacl netbsd openbsd solaris
 
 package socktest
 

src/net/internal/socktest/sys_unix.go

@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// +build darwin dragonfly freebsd linux nacl netbsd openbsd solaris
+// +build darwin dragonfly freebsd js,wasm linux nacl netbsd openbsd solaris
 
 package socktest
 

src/net/ip_test.go

@@ -2,6 +2,8 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+// +build !js
+
 package net
 
 import (

src/net/iprawsock_posix.go

@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// +build darwin dragonfly freebsd linux nacl netbsd openbsd solaris windows
+// +build darwin dragonfly freebsd js,wasm linux nacl netbsd openbsd solaris windows
 
 package net
 

src/net/iprawsock_test.go

@@ -2,6 +2,8 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+// +build !js
+
 package net
 
 import (

src/net/ipsock_posix.go

@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// +build darwin dragonfly freebsd linux nacl netbsd openbsd solaris windows
+// +build darwin dragonfly freebsd js,wasm linux nacl netbsd openbsd solaris windows
 
 package net
 

src/net/listen_test.go

@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// +build !plan9
+// +build !js,!plan9
 
 package net
 

src/net/lookup_nacl.go → src/net/lookup_fake.go

@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// +build nacl
+// +build nacl js,wasm
 
 package net
 

src/net/lookup_test.go

@@ -2,6 +2,8 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+// +build !js
+
 package net
 
 import (

src/net/main_conf_test.go

@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// +build !nacl,!plan9,!windows
+// +build !js,!nacl,!plan9,!windows
 
 package net
 

src/net/main_noconf_test.go

@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// +build nacl plan9 windows
+// +build js,wasm nacl plan9 windows
 
 package net
 

src/net/main_posix_test.go

@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// +build !plan9
+// +build !js,!plan9
 
 package net
 

src/net/main_test.go

@@ -2,6 +2,8 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+// +build !js
+
 package net
 
 import (

src/net/mockserver_test.go

@@ -2,6 +2,8 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+// +build !js
+
 package net
 
 import (

src/net/net.go

@@ -229,7 +229,7 @@ func (c *conn) SetDeadline(t time.Time) error {
 	if !c.ok() {
 		return syscall.EINVAL
 	}
-	if err := c.fd.pfd.SetDeadline(t); err != nil {
+	if err := c.fd.SetDeadline(t); err != nil {
 		return &OpError{Op: "set", Net: c.fd.net, Source: nil, Addr: c.fd.laddr, Err: err}
 	}
 	return nil
@@ -240,7 +240,7 @@ func (c *conn) SetReadDeadline(t time.Time) error {
 	if !c.ok() {
 		return syscall.EINVAL
 	}
-	if err := c.fd.pfd.SetReadDeadline(t); err != nil {
+	if err := c.fd.SetReadDeadline(t); err != nil {
 		return &OpError{Op: "set", Net: c.fd.net, Source: nil, Addr: c.fd.laddr, Err: err}
 	}
 	return nil
@@ -251,7 +251,7 @@ func (c *conn) SetWriteDeadline(t time.Time) error {
 	if !c.ok() {
 		return syscall.EINVAL
 	}
-	if err := c.fd.pfd.SetWriteDeadline(t); err != nil {
+	if err := c.fd.SetWriteDeadline(t); err != nil {
 		return &OpError{Op: "set", Net: c.fd.net, Source: nil, Addr: c.fd.laddr, Err: err}
 	}
 	return nil

src/net/net_fake.go

+// Copyright 2018 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.
+
+// Fake networking for js/wasm. It is intended to allow tests of other package to pass.
+
+// +build js,wasm
+
+package net
+
+import (
+	"context"
+	"internal/poll"
+	"io"
+	"os"
+	"sync"
+	"syscall"
+	"time"
+)
+
+var listenersMu sync.Mutex
+var listeners = make(map[string]*netFD)
+
+var portCounterMu sync.Mutex
+var portCounter = 0
+
+func nextPort() int {
+	portCounterMu.Lock()
+	defer portCounterMu.Unlock()
+	portCounter++
+	return portCounter
+}
+
+// Network file descriptor.
+type netFD struct {
+	r        *bufferedPipe
+	w        *bufferedPipe
+	incoming chan *netFD
+
+	closedMu sync.Mutex
+	closed   bool
+
+	// immutable until Close
+	listener bool
+	family   int
+	sotype   int
+	net      string
+	laddr    Addr
+	raddr    Addr
+
+	// unused
+	pfd         poll.FD
+	isConnected bool
+}
+
+// socket returns a network file descriptor that is ready for
+// asynchronous I/O using the network poller.
+func socket(ctx context.Context, net string, family, sotype, proto int, ipv6only bool, laddr, raddr sockaddr, ctrlFn func(string, string, syscall.RawConn) error) (*netFD, error) {
+	fd := &netFD{family: family, sotype: sotype, net: net}
+
+	if laddr != nil && raddr == nil { // listener
+		l := laddr.(*TCPAddr)
+		fd.laddr = &TCPAddr{
+			IP:   l.IP,
+			Port: nextPort(),
+			Zone: l.Zone,
+		}
+		fd.listener = true
+		fd.incoming = make(chan *netFD, 1024)
+		listenersMu.Lock()
+		listeners[fd.laddr.(*TCPAddr).String()] = fd
+		listenersMu.Unlock()
+		return fd, nil
+	}
+
+	fd.laddr = &TCPAddr{
+		IP:   IPv4(127, 0, 0, 1),
+		Port: nextPort(),
+	}
+	fd.raddr = raddr
+	fd.r = newBufferedPipe(65536)
+	fd.w = newBufferedPipe(65536)
+
+	fd2 := &netFD{family: fd.family, sotype: sotype, net: net}
+	fd2.laddr = fd.raddr
+	fd2.raddr = fd.laddr
+	fd2.r = fd.w
+	fd2.w = fd.r
+	listenersMu.Lock()
+	l, ok := listeners[fd.raddr.(*TCPAddr).String()]
+	if !ok {
+		listenersMu.Unlock()
+		return nil, syscall.ECONNREFUSED
+	}
+	l.incoming <- fd2
+	listenersMu.Unlock()
+
+	return fd, nil
+}
+
+func (fd *netFD) Read(p []byte) (n int, err error) {
+	return fd.r.Read(p)
+}
+
+func (fd *netFD) Write(p []byte) (nn int, err error) {
+	return fd.w.Write(p)
+}
+
+func (fd *netFD) Close() error {
+	fd.closedMu.Lock()
+	if fd.closed {
+		fd.closedMu.Unlock()
+		return nil
+	}
+	fd.closed = true
+	fd.closedMu.Unlock()
+
+	if fd.listener {
+		listenersMu.Lock()
+		delete(listeners, fd.laddr.String())
+		close(fd.incoming)
+		fd.listener = false
+		listenersMu.Unlock()
+		return nil
+	}
+
+	fd.r.Close()
+	fd.w.Close()
+	return nil
+}
+
+func (fd *netFD) closeRead() error {
+	fd.r.Close()
+	return nil
+}
+
+func (fd *netFD) closeWrite() error {
+	fd.w.Close()
+	return nil
+}
+
+func (fd *netFD) accept() (*netFD, error) {
+	c, ok := <-fd.incoming
+	if !ok {
+		return nil, syscall.EINVAL
+	}
+	return c, nil
+}
+
+func (fd *netFD) SetDeadline(t time.Time) error {
+	fd.r.SetReadDeadline(t)
+	fd.w.SetWriteDeadline(t)
+	return nil
+}
+
+func (fd *netFD) SetReadDeadline(t time.Time) error {
+	fd.r.SetReadDeadline(t)
+	return nil
+}
+
+func (fd *netFD) SetWriteDeadline(t time.Time) error {
+	fd.w.SetWriteDeadline(t)
+	return nil
+}
+
+func newBufferedPipe(softLimit int) *bufferedPipe {
+	p := &bufferedPipe{softLimit: softLimit}
+	p.rCond.L = &p.mu
+	p.wCond.L = &p.mu
+	return p
+}
+
+type bufferedPipe struct {
+	softLimit int
+	mu        sync.Mutex
+	buf       []byte
+	closed    bool
+	rCond     sync.Cond
+	wCond     sync.Cond
+	rDeadline time.Time
+	wDeadline time.Time
+}
+
+func (p *bufferedPipe) Read(b []byte) (int, error) {
+	p.mu.Lock()
+	defer p.mu.Unlock()
+
+	for {
+		if p.closed && len(p.buf) == 0 {
+			return 0, io.EOF
+		}
+		if !p.rDeadline.IsZero() {
+			d := time.Until(p.rDeadline)
+			if d <= 0 {
+				return 0, syscall.EAGAIN
+			}
+			time.AfterFunc(d, p.rCond.Broadcast)
+		}
+		if len(p.buf) > 0 {
+			break
+		}
+		p.rCond.Wait()
+	}
+
+	n := copy(b, p.buf)
+	p.buf = p.buf[n:]
+	p.wCond.Broadcast()
+	return n, nil
+}
+
+func (p *bufferedPipe) Write(b []byte) (int, error) {
+	p.mu.Lock()
+	defer p.mu.Unlock()
+
+	for {
+		if p.closed {
+			return 0, syscall.ENOTCONN
+		}
+		if !p.wDeadline.IsZero() {
+			d := time.Until(p.wDeadline)
+			if d <= 0 {
+				return 0, syscall.EAGAIN
+			}
+			time.AfterFunc(d, p.wCond.Broadcast)
+		}
+		if len(p.buf) <= p.softLimit {
+			break
+		}
+		p.wCond.Wait()
+	}
+
+	p.buf = append(p.buf, b...)
+	p.rCond.Broadcast()
+	return len(b), nil
+}
+
+func (p *bufferedPipe) Close() {
+	p.mu.Lock()
+	defer p.mu.Unlock()
+
+	p.closed = true
+	p.rCond.Broadcast()
+	p.wCond.Broadcast()
+}
+
+func (p *bufferedPipe) SetReadDeadline(t time.Time) {
+	p.mu.Lock()
+	defer p.mu.Unlock()
+
+	p.rDeadline = t
+	p.rCond.Broadcast()
+}
+
+func (p *bufferedPipe) SetWriteDeadline(t time.Time) {
+	p.mu.Lock()
+	defer p.mu.Unlock()
+
+	p.wDeadline = t
+	p.wCond.Broadcast()
+}
+
+func sysSocket(family, sotype, proto int) (int, error) {
+	return 0, syscall.ENOSYS
+}
+
+func (fd *netFD) readFrom(p []byte) (n int, sa syscall.Sockaddr, err error) {
+	return 0, nil, syscall.ENOSYS
+}
+
+func (fd *netFD) readMsg(p []byte, oob []byte) (n, oobn, flags int, sa syscall.Sockaddr, err error) {
+	return 0, 0, 0, nil, syscall.ENOSYS
+}
+
+func (fd *netFD) writeTo(p []byte, sa syscall.Sockaddr) (n int, err error) {
+	return 0, syscall.ENOSYS
+}
+
+func (fd *netFD) writeMsg(p []byte, oob []byte, sa syscall.Sockaddr) (n int, oobn int, err error) {
+	return 0, 0, syscall.ENOSYS
+}
+
+func (fd *netFD) dup() (f *os.File, err error) {
+	return nil, syscall.ENOSYS
+}

src/net/net_test.go

@@ -2,6 +2,8 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+// +build !js
+
 package net
 
 import (

src/net/packetconn_test.go

@@ -5,6 +5,8 @@
 // This file implements API tests across platforms and will never have a build
 // tag.
 
+// +build !js
+
 package net
 
 import (

src/net/port_unix.go

@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// +build darwin dragonfly freebsd linux netbsd openbsd solaris nacl
+// +build darwin dragonfly freebsd js,wasm linux netbsd openbsd solaris nacl
 
 // Read system port mappings from /etc/services
 

src/net/protoconn_test.go

@@ -5,6 +5,8 @@
 // This file implements API tests across platforms and will never have a build
 // tag.
 
+// +build !js
+
 package net
 
 import (

src/net/rawconn_stub_test.go

@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// +build nacl plan9
+// +build js,wasm nacl plan9
 
 package net
 

src/net/rawconn_test.go

@@ -2,6 +2,8 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+// +build !js
+
 package net
 
 import (

src/net/sendfile_stub.go

@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// +build darwin nacl netbsd openbsd
+// +build darwin js,wasm nacl netbsd openbsd
 
 package net
 

src/net/sendfile_test.go

@@ -2,6 +2,8 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+// +build !js
+
 package net
 
 import (

src/net/server_test.go

@@ -2,6 +2,8 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+// +build !js
+
 package net
 
 import (

src/net/smtp/smtp_test.go

@@ -725,7 +725,7 @@ QUIT
 `
 
 func TestTLSClient(t *testing.T) {
-	if runtime.GOOS == "freebsd" && runtime.GOARCH == "amd64" {
+	if (runtime.GOOS == "freebsd" && runtime.GOARCH == "amd64") || runtime.GOOS == "js" {
 		testenv.SkipFlaky(t, 19229)
 	}
 	ln := newLocalListener(t)

src/net/sock_posix.go

@@ -13,29 +13,6 @@ import (
 	"syscall"
 )
 
-// A sockaddr represents a TCP, UDP, IP or Unix network endpoint
-// address that can be converted into a syscall.Sockaddr.
-type sockaddr interface {
-	Addr
-
-	// family returns the platform-dependent address family
-	// identifier.
-	family() int
-
-	// isWildcard reports whether the address is a wildcard
-	// address.
-	isWildcard() bool
-
-	// sockaddr returns the address converted into a syscall
-	// sockaddr type that implements syscall.Sockaddr
-	// interface. It returns a nil interface when the address is
-	// nil.
-	sockaddr(family int) (syscall.Sockaddr, error)
-
-	// toLocal maps the zero address to a local system address (127.0.0.1 or ::1)
-	toLocal(net string) sockaddr
-}
-
 // socket returns a network file descriptor that is ready for
 // asynchronous I/O using the network poller.
 func socket(ctx context.Context, net string, family, sotype, proto int, ipv6only bool, laddr, raddr sockaddr, ctrlFn func(string, string, syscall.RawConn) error) (fd *netFD, err error) {

src/net/sock_stub.go

@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// +build nacl solaris
+// +build nacl js,wasm solaris
 
 package net
 

src/net/sockaddr_posix.go

+// Copyright 2018 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.
+
+// +build darwin dragonfly freebsd js,wasm linux nacl netbsd openbsd solaris windows
+
+package net
+
+import (
+	"syscall"
+)
+
+// A sockaddr represents a TCP, UDP, IP or Unix network endpoint
+// address that can be converted into a syscall.Sockaddr.
+type sockaddr interface {
+	Addr
+
+	// family returns the platform-dependent address family
+	// identifier.
+	family() int
+
+	// isWildcard reports whether the address is a wildcard
+	// address.
+	isWildcard() bool
+
+	// sockaddr returns the address converted into a syscall
+	// sockaddr type that implements syscall.Sockaddr
+	// interface. It returns a nil interface when the address is
+	// nil.
+	sockaddr(family int) (syscall.Sockaddr, error)
+
+	// toLocal maps the zero address to a local system address (127.0.0.1 or ::1)
+	toLocal(net string) sockaddr
+}

src/net/sockopt_stub.go

@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// +build nacl
+// +build nacl js,wasm
 
 package net
 

src/net/sockoptip_stub.go

@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// +build nacl
+// +build nacl js,wasm
 
 package net
 

src/net/tcpsock_posix.go

@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// +build darwin dragonfly freebsd linux nacl netbsd openbsd solaris windows
+// +build darwin dragonfly freebsd js,wasm linux nacl netbsd openbsd solaris windows
 
 package net
 

src/net/tcpsock_test.go

@@ -2,6 +2,8 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+// +build !js
+
 package net
 
 import (

src/net/tcpsock_unix_test.go

@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// +build !plan9,!windows
+// +build !js,!plan9,!windows
 
 package net
 

src/net/tcpsockopt_stub.go

@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// +build nacl
+// +build nacl js,wasm
 
 package net
 

src/net/timeout_test.go

@@ -2,6 +2,8 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+// +build !js
+
 package net
 
 import (

src/net/udpsock_posix.go

@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// +build darwin dragonfly freebsd linux nacl netbsd openbsd solaris windows
+// +build darwin dragonfly freebsd js,wasm linux nacl netbsd openbsd solaris windows
 
 package net
 

src/net/udpsock_test.go

@@ -2,6 +2,8 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+// +build !js
+
 package net
 
 import (

src/net/unixsock_posix.go

@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// +build darwin dragonfly freebsd linux nacl netbsd openbsd solaris windows
+// +build darwin dragonfly freebsd js,wasm linux nacl netbsd openbsd solaris windows
 
 package net
 

src/net/unixsock_test.go

@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// +build !nacl,!plan9,!windows
+// +build !js,!nacl,!plan9,!windows
 
 package net
 

src/net/writev_test.go

@@ -2,6 +2,8 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+// +build !js
+
 package net
 
 import (

src/runtime/netpoll.go

@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// +build darwin dragonfly freebsd linux nacl netbsd openbsd solaris windows
+// +build darwin dragonfly freebsd js,wasm linux nacl netbsd openbsd solaris windows
 
 package runtime
 

src/runtime/netpoll_nacl.go → src/runtime/netpoll_fake.go

@@ -2,8 +2,10 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// Fake network poller for NaCl.
-// Should never be used, because NaCl network connections do not honor "SetNonblock".
+// Fake network poller for NaCl and wasm/js.
+// Should never be used, because NaCl and wasm/js network connections do not honor "SetNonblock".
+
+// +build nacl js,wasm
 
 package runtime
 

src/syscall/net_js.go

+// Copyright 2018 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.
+
+// js/wasm uses fake networking directly implemented in the net package.
+// This file only exists to make the compiler happy.
+
+// +build js,wasm
+
+package syscall
+
+const (
+	AF_UNSPEC = iota
+	AF_UNIX
+	AF_INET
+	AF_INET6
+)
+
+const (
+	SOCK_STREAM = 1 + iota
+	SOCK_DGRAM
+	SOCK_RAW
+	SOCK_SEQPACKET
+)
+
+const (
+	IPPROTO_IP   = 0
+	IPPROTO_IPV4 = 4
+	IPPROTO_IPV6 = 0x29
+	IPPROTO_TCP  = 6
+	IPPROTO_UDP  = 0x11
+)
+
+const (
+	_ = iota
+	IPV6_V6ONLY
+	SOMAXCONN
+	SO_ERROR
+)
+
+type Sockaddr interface {
+}
+
+type SockaddrInet4 struct {
+	Port int
+	Addr [4]byte
+}
+
+type SockaddrInet6 struct {
+	Port   int
+	ZoneId uint32
+	Addr   [16]byte
+}
+
+type SockaddrUnix struct {
+	Name string
+}
+
+func Socket(proto, sotype, unused int) (fd int, err error) {
+	return 0, ENOSYS
+}
+
+func Bind(fd int, sa Sockaddr) error {
+	return ENOSYS
+}
+
+func StopIO(fd int) error {
+	return ENOSYS
+}
+
+func Listen(fd int, backlog int) error {
+	return ENOSYS
+}
+
+func Accept(fd int) (newfd int, sa Sockaddr, err error) {
+	return 0, nil, ENOSYS
+}
+
+func Connect(fd int, sa Sockaddr) error {
+	return ENOSYS
+}
+
+func Recvfrom(fd int, p []byte, flags int) (n int, from Sockaddr, err error) {
+	return 0, nil, ENOSYS
+}
+
+func Sendto(fd int, p []byte, flags int, to Sockaddr) error {
+	return ENOSYS
+}
+
+func Recvmsg(fd int, p, oob []byte, flags int) (n, oobn, recvflags int, from Sockaddr, err error) {
+	return 0, 0, 0, nil, ENOSYS
+}
+
+func SendmsgN(fd int, p, oob []byte, to Sockaddr, flags int) (n int, err error) {
+	return 0, ENOSYS
+}
+
+func GetsockoptInt(fd, level, opt int) (value int, err error) {
+	return 0, ENOSYS
+}
+
+func SetsockoptInt(fd, level, opt int, value int) error {
+	return nil
+}
+
+func SetReadDeadline(fd int, t int64) error {
+	return ENOSYS
+}
+
+func SetWriteDeadline(fd int, t int64) error {
+	return ENOSYS
+}
+
+func Shutdown(fd int, how int) error {
+	return ENOSYS
+}
+
+func SetNonblock(fd int, nonblocking bool) error {
+	return nil
+}