net: deduplicate TCP socket code

This change consolidates functions and methods related to TCPAddr,
TCPConn and TCPListener for maintenance purpose, especially for
documentation. Also refactors Dial error code paths.

The followup changes will update comments and examples.

Updates #10624.

Change-Id: I3333ee218ebcd08928f9e2826cd1984d15ea153e
Reviewed-on: https://go-review.googlesource.com/20009Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Mikio Hara <mikioh.mikioh@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>

src/net/dial.go

@@ -407,7 +407,7 @@ func dialSingle(ctx *dialContext, ra Addr, deadline time.Time, cancel <-chan str
 		return nil, &OpError{Op: "dial", Net: ctx.network, Source: la, Addr: ra, Err: &AddrError{Err: "unexpected address type", Addr: ctx.address}}
 	}
 	if err != nil {
-		return nil, err // c is non-nil interface containing nil pointer
+		return nil, &OpError{Op: "dial", Net: ctx.network, Source: la, Addr: ra, Err: err} // c is non-nil interface containing nil pointer
 	}
 	return c, nil
 }

src/net/error_test.go

@@ -91,6 +91,9 @@ second:
 	case *os.SyscallError:
 		nestedErr = err.Err
 		goto third
+	case *os.PathError: // for Plan 9
+		nestedErr = err.Err
+		goto third
 	}
 	switch nestedErr {
 	case errCanceled, errClosing, errMissingAddress:
@@ -543,6 +546,9 @@ second:
 	case *os.SyscallError:
 		nestedErr = err.Err
 		goto third
+	case *os.PathError: // for Plan 9
+		nestedErr = err.Err
+		goto third
 	}
 	switch nestedErr {
 	case errClosing, errTimeout:

src/net/iprawsock_posix.go

@@ -204,25 +204,29 @@ func (c *IPConn) WriteMsgIP(b, oob []byte, addr *IPAddr) (n, oobn int, err error
 // netProto, which must be "ip", "ip4", or "ip6" followed by a colon
 // and a protocol number or name.
 func DialIP(netProto string, laddr, raddr *IPAddr) (*IPConn, error) {
-	return dialIP(netProto, laddr, raddr, noDeadline)
+	c, err := dialIP(netProto, laddr, raddr, noDeadline)
+	if err != nil {
+		return nil, &OpError{Op: "dial", Net: netProto, Source: laddr.opAddr(), Addr: raddr.opAddr(), Err: err}
+	}
+	return c, nil
 }
 
 func dialIP(netProto string, laddr, raddr *IPAddr, deadline time.Time) (*IPConn, error) {
 	net, proto, err := parseNetwork(netProto)
 	if err != nil {
-		return nil, &OpError{Op: "dial", Net: netProto, Source: laddr.opAddr(), Addr: raddr.opAddr(), Err: err}
+		return nil, err
 	}
 	switch net {
 	case "ip", "ip4", "ip6":
 	default:
-		return nil, &OpError{Op: "dial", Net: netProto, Source: laddr.opAddr(), Addr: raddr.opAddr(), Err: UnknownNetworkError(netProto)}
+		return nil, UnknownNetworkError(netProto)
 	}
 	if raddr == nil {
-		return nil, &OpError{Op: "dial", Net: netProto, Source: laddr.opAddr(), Addr: nil, Err: errMissingAddress}
+		return nil, errMissingAddress
 	}
 	fd, err := internetSocket(net, laddr, raddr, deadline, syscall.SOCK_RAW, proto, "dial", noCancel)
 	if err != nil {
-		return nil, &OpError{Op: "dial", Net: netProto, Source: laddr.opAddr(), Addr: raddr.opAddr(), Err: err}
+		return nil, err
 	}
 	return newIPConn(fd), nil
 }

src/net/ipsock_plan9.go

@@ -169,23 +169,23 @@ func dialPlan9(net string, laddr, raddr Addr) (fd *netFD, err error) {
 	defer func() { netErr(err) }()
 	f, dest, proto, name, err := startPlan9(net, raddr)
 	if err != nil {
-		return nil, &OpError{Op: "dial", Net: net, Source: laddr, Addr: raddr, Err: err}
+		return nil, err
 	}
 	_, err = f.WriteString("connect " + dest)
 	if err != nil {
 		f.Close()
-		return nil, &OpError{Op: "dial", Net: f.Name(), Source: laddr, Addr: raddr, Err: err}
+		return nil, err
 	}
 	data, err := os.OpenFile(netdir+"/"+proto+"/"+name+"/data", os.O_RDWR, 0)
 	if err != nil {
 		f.Close()
-		return nil, &OpError{Op: "dial", Net: net, Source: laddr, Addr: raddr, Err: err}
+		return nil, err
 	}
 	laddr, err = readPlan9Addr(proto, netdir+"/"+proto+"/"+name+"/local")
 	if err != nil {
 		data.Close()
 		f.Close()
-		return nil, &OpError{Op: "dial", Net: proto, Source: laddr, Addr: raddr, Err: err}
+		return nil, err
 	}
 	return newFD(proto, name, f, data, laddr, raddr)
 }
@@ -194,17 +194,17 @@ func listenPlan9(net string, laddr Addr) (fd *netFD, err error) {
 	defer func() { netErr(err) }()
 	f, dest, proto, name, err := startPlan9(net, laddr)
 	if err != nil {
-		return nil, &OpError{Op: "listen", Net: net, Source: nil, Addr: laddr, Err: err}
+		return nil, err
 	}
 	_, err = f.WriteString("announce " + dest)
 	if err != nil {
 		f.Close()
-		return nil, &OpError{Op: "announce", Net: proto, Source: nil, Addr: laddr, Err: err}
+		return nil, err
 	}
 	laddr, err = readPlan9Addr(proto, netdir+"/"+proto+"/"+name+"/local")
 	if err != nil {
 		f.Close()
-		return nil, &OpError{Op: "listen", Net: net, Source: nil, Addr: laddr, Err: err}
+		return nil, err
 	}
 	return newFD(proto, name, f, nil, laddr, nil)
 }
@@ -221,25 +221,25 @@ func (fd *netFD) acceptPlan9() (nfd *netFD, err error) {
 	defer fd.readUnlock()
 	f, err := os.Open(fd.dir + "/listen")
 	if err != nil {
-		return nil, &OpError{Op: "accept", Net: fd.dir + "/listen", Source: nil, Addr: fd.laddr, Err: err}
+		return nil, err
 	}
 	var buf [16]byte
 	n, err := f.Read(buf[:])
 	if err != nil {
 		f.Close()
-		return nil, &OpError{Op: "accept", Net: fd.dir + "/listen", Source: nil, Addr: fd.laddr, Err: err}
+		return nil, err
 	}
 	name := string(buf[:n])
 	data, err := os.OpenFile(netdir+"/"+fd.net+"/"+name+"/data", os.O_RDWR, 0)
 	if err != nil {
 		f.Close()
-		return nil, &OpError{Op: "accept", Net: fd.net, Source: nil, Addr: fd.laddr, Err: err}
+		return nil, err
 	}
 	raddr, err := readPlan9Addr(fd.net, netdir+"/"+fd.net+"/"+name+"/remote")
 	if err != nil {
 		data.Close()
 		f.Close()
-		return nil, &OpError{Op: "accept", Net: fd.net, Source: nil, Addr: fd.laddr, Err: err}
+		return nil, err
 	}
 	return newFD(fd.net, name, f, data, fd.laddr, raddr)
 }

src/net/sockopt_plan9.go

@@ -4,6 +4,8 @@
 
 package net
 
+import "syscall"
+
 func setKeepAlive(fd *netFD, keepalive bool) error {
 	if keepalive {
 		_, e := fd.ctl.WriteAt([]byte("keepalive"), 0)
@@ -11,3 +13,7 @@ func setKeepAlive(fd *netFD, keepalive bool) error {
 	}
 	return nil
 }
+
+func setLinger(fd *netFD, sec int) error {
+	return syscall.EPLAN9
+}

src/net/tcpsock.go

@@ -4,6 +4,13 @@
 
 package net
 
+import (
+	"io"
+	"os"
+	"syscall"
+	"time"
+)
+
 // TCPAddr represents the address of a TCP end point.
 type TCPAddr struct {
 	IP   IP
@@ -59,3 +66,228 @@ func ResolveTCPAddr(net, addr string) (*TCPAddr, error) {
 	}
 	return addrs.first(isIPv4).(*TCPAddr), nil
 }
+
+// TCPConn is an implementation of the Conn interface for TCP network
+// connections.
+type TCPConn struct {
+	conn
+}
+
+// ReadFrom implements the io.ReaderFrom ReadFrom method.
+func (c *TCPConn) ReadFrom(r io.Reader) (int64, error) {
+	if !c.ok() {
+		return 0, syscall.EINVAL
+	}
+	n, err := c.readFrom(r)
+	if err != nil && err != io.EOF {
+		err = &OpError{Op: "read", Net: c.fd.net, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}
+	}
+	return n, err
+}
+
+// CloseRead shuts down the reading side of the TCP connection.
+// Most callers should just use Close.
+func (c *TCPConn) CloseRead() error {
+	if !c.ok() {
+		return syscall.EINVAL
+	}
+	if err := c.fd.closeRead(); err != nil {
+		return &OpError{Op: "close", Net: c.fd.net, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}
+	}
+	return nil
+}
+
+// CloseWrite shuts down the writing side of the TCP connection.
+// Most callers should just use Close.
+func (c *TCPConn) CloseWrite() error {
+	if !c.ok() {
+		return syscall.EINVAL
+	}
+	if err := c.fd.closeWrite(); err != nil {
+		return &OpError{Op: "close", Net: c.fd.net, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}
+	}
+	return nil
+}
+
+// SetLinger sets the behavior of Close on a connection which still
+// has data waiting to be sent or to be acknowledged.
+//
+// If sec < 0 (the default), the operating system finishes sending the
+// data in the background.
+//
+// If sec == 0, the operating system discards any unsent or
+// unacknowledged data.
+//
+// If sec > 0, the data is sent in the background as with sec < 0. On
+// some operating systems after sec seconds have elapsed any remaining
+// unsent data may be discarded.
+func (c *TCPConn) SetLinger(sec int) error {
+	if !c.ok() {
+		return syscall.EINVAL
+	}
+	if err := setLinger(c.fd, sec); err != nil {
+		return &OpError{Op: "set", Net: c.fd.net, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}
+	}
+	return nil
+}
+
+// SetKeepAlive sets whether the operating system should send
+// keepalive messages on the connection.
+func (c *TCPConn) SetKeepAlive(keepalive bool) error {
+	if !c.ok() {
+		return syscall.EINVAL
+	}
+	if err := setKeepAlive(c.fd, keepalive); err != nil {
+		return &OpError{Op: "set", Net: c.fd.net, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}
+	}
+	return nil
+}
+
+// SetKeepAlivePeriod sets period between keep alives.
+func (c *TCPConn) SetKeepAlivePeriod(d time.Duration) error {
+	if !c.ok() {
+		return syscall.EINVAL
+	}
+	if err := setKeepAlivePeriod(c.fd, d); err != nil {
+		return &OpError{Op: "set", Net: c.fd.net, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}
+	}
+	return nil
+}
+
+// SetNoDelay controls whether the operating system should delay
+// packet transmission in hopes of sending fewer packets (Nagle's
+// algorithm).  The default is true (no delay), meaning that data is
+// sent as soon as possible after a Write.
+func (c *TCPConn) SetNoDelay(noDelay bool) error {
+	if !c.ok() {
+		return syscall.EINVAL
+	}
+	if err := setNoDelay(c.fd, noDelay); err != nil {
+		return &OpError{Op: "set", Net: c.fd.net, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}
+	}
+	return nil
+}
+
+func newTCPConn(fd *netFD) *TCPConn {
+	c := &TCPConn{conn{fd}}
+	setNoDelay(c.fd, true)
+	return c
+}
+
+// DialTCP connects to the remote address raddr on the network net,
+// which must be "tcp", "tcp4", or "tcp6".  If laddr is not nil, it is
+// used as the local address for the connection.
+func DialTCP(net string, laddr, raddr *TCPAddr) (*TCPConn, error) {
+	switch net {
+	case "tcp", "tcp4", "tcp6":
+	default:
+		return nil, &OpError{Op: "dial", Net: net, Source: laddr.opAddr(), Addr: raddr.opAddr(), Err: UnknownNetworkError(net)}
+	}
+	if raddr == nil {
+		return nil, &OpError{Op: "dial", Net: net, Source: laddr.opAddr(), Addr: nil, Err: errMissingAddress}
+	}
+	c, err := dialTCP(net, laddr, raddr, noDeadline, noCancel)
+	if err != nil {
+		return nil, &OpError{Op: "dial", Net: net, Source: laddr.opAddr(), Addr: raddr.opAddr(), Err: err}
+	}
+	return c, nil
+}
+
+// TCPListener is a TCP network listener. Clients should typically
+// use variables of type Listener instead of assuming TCP.
+type TCPListener struct {
+	fd *netFD
+}
+
+// AcceptTCP accepts the next incoming call and returns the new
+// connection.
+func (l *TCPListener) AcceptTCP() (*TCPConn, error) {
+	if !l.ok() {
+		return nil, syscall.EINVAL
+	}
+	c, err := l.accept()
+	if err != nil {
+		return nil, &OpError{Op: "accept", Net: l.fd.net, Source: nil, Addr: l.fd.laddr, Err: err}
+	}
+	return c, nil
+}
+
+// Accept implements the Accept method in the Listener interface; it
+// waits for the next call and returns a generic Conn.
+func (l *TCPListener) Accept() (Conn, error) {
+	if !l.ok() {
+		return nil, syscall.EINVAL
+	}
+	c, err := l.accept()
+	if err != nil {
+		return nil, &OpError{Op: "accept", Net: l.fd.net, Source: nil, Addr: l.fd.laddr, Err: err}
+	}
+	return c, nil
+}
+
+// Close stops listening on the TCP address.
+// Already Accepted connections are not closed.
+func (l *TCPListener) Close() error {
+	if !l.ok() {
+		return syscall.EINVAL
+	}
+	if err := l.close(); err != nil {
+		return &OpError{Op: "close", Net: l.fd.net, Source: nil, Addr: l.fd.laddr, Err: err}
+	}
+	return nil
+}
+
+// Addr returns the listener's network address, a *TCPAddr.
+// The Addr returned is shared by all invocations of Addr, so
+// do not modify it.
+func (l *TCPListener) Addr() Addr { return l.fd.laddr }
+
+// SetDeadline sets the deadline associated with the listener.
+// A zero time value disables the deadline.
+func (l *TCPListener) SetDeadline(t time.Time) error {
+	if !l.ok() {
+		return syscall.EINVAL
+	}
+	if err := l.fd.setDeadline(t); err != nil {
+		return &OpError{Op: "set", Net: l.fd.net, Source: nil, Addr: l.fd.laddr, Err: err}
+	}
+	return nil
+}
+
+// File returns a copy of the underlying os.File, set to blocking
+// mode. It is the caller's responsibility to close f when finished.
+// Closing l does not affect f, and closing f does not affect l.
+//
+// The returned os.File's file descriptor is different from the
+// connection's. Attempting to change properties of the original
+// using this duplicate may or may not have the desired effect.
+func (l *TCPListener) File() (f *os.File, err error) {
+	if !l.ok() {
+		return nil, syscall.EINVAL
+	}
+	f, err = l.file()
+	if err != nil {
+		return nil, &OpError{Op: "file", Net: l.fd.net, Source: nil, Addr: l.fd.laddr, Err: err}
+	}
+	return
+}
+
+// ListenTCP announces on the TCP address laddr and returns a TCP
+// listener. Net must be "tcp", "tcp4", or "tcp6".  If laddr has a
+// port of 0, ListenTCP will choose an available port. The caller can
+// use the Addr method of TCPListener to retrieve the chosen address.
+func ListenTCP(net string, laddr *TCPAddr) (*TCPListener, error) {
+	switch net {
+	case "tcp", "tcp4", "tcp6":
+	default:
+		return nil, &OpError{Op: "listen", Net: net, Source: nil, Addr: laddr.opAddr(), Err: UnknownNetworkError(net)}
+	}
+	if laddr == nil {
+		laddr = &TCPAddr{}
+	}
+	ln, err := listenTCP(net, laddr)
+	if err != nil {
+		return nil, &OpError{Op: "listen", Net: net, Source: nil, Addr: laddr.opAddr(), Err: err}
+	}
+	return ln, nil
+}

src/net/tcpsock_plan9.go

@@ -7,107 +7,11 @@ package net
 import (
 	"io"
 	"os"
-	"syscall"
 	"time"
 )
 
-// TCPConn is an implementation of the Conn interface for TCP network
-// connections.
-type TCPConn struct {
-	conn
-}
-
-func newTCPConn(fd *netFD) *TCPConn {
-	return &TCPConn{conn{fd}}
-}
-
-// ReadFrom implements the io.ReaderFrom ReadFrom method.
-func (c *TCPConn) ReadFrom(r io.Reader) (int64, error) {
-	n, err := genericReadFrom(c, r)
-	if err != nil && err != io.EOF {
-		err = &OpError{Op: "read", Net: c.fd.dir, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}
-	}
-	return n, err
-}
-
-// CloseRead shuts down the reading side of the TCP connection.
-// Most callers should just use Close.
-func (c *TCPConn) CloseRead() error {
-	if !c.ok() {
-		return syscall.EINVAL
-	}
-	err := c.fd.closeRead()
-	if err != nil {
-		err = &OpError{Op: "close", Net: c.fd.dir, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}
-	}
-	return err
-}
-
-// CloseWrite shuts down the writing side of the TCP connection.
-// Most callers should just use Close.
-func (c *TCPConn) CloseWrite() error {
-	if !c.ok() {
-		return syscall.EINVAL
-	}
-	err := c.fd.closeWrite()
-	if err != nil {
-		err = &OpError{Op: "close", Net: c.fd.dir, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}
-	}
-	return err
-}
-
-// SetLinger sets the behavior of Close on a connection which still
-// has data waiting to be sent or to be acknowledged.
-//
-// If sec < 0 (the default), the operating system finishes sending the
-// data in the background.
-//
-// If sec == 0, the operating system discards any unsent or
-// unacknowledged data.
-//
-// If sec > 0, the data is sent in the background as with sec < 0. On
-// some operating systems after sec seconds have elapsed any remaining
-// unsent data may be discarded.
-func (c *TCPConn) SetLinger(sec int) error {
-	return &OpError{Op: "set", Net: c.fd.dir, Source: c.fd.laddr, Addr: c.fd.raddr, Err: syscall.EPLAN9}
-}
-
-// SetKeepAlive sets whether the operating system should send
-// keepalive messages on the connection.
-func (c *TCPConn) SetKeepAlive(keepalive bool) error {
-	if !c.ok() {
-		return syscall.EPLAN9
-	}
-	if err := setKeepAlive(c.fd, keepalive); err != nil {
-		return &OpError{Op: "set", Net: c.fd.dir, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}
-	}
-	return nil
-}
-
-// SetKeepAlivePeriod sets period between keep alives.
-func (c *TCPConn) SetKeepAlivePeriod(d time.Duration) error {
-	if !c.ok() {
-		return syscall.EPLAN9
-	}
-	if err := setKeepAlivePeriod(c.fd, d); err != nil {
-		return &OpError{Op: "set", Net: c.fd.dir, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}
-	}
-	return nil
-}
-
-// SetNoDelay controls whether the operating system should delay
-// packet transmission in hopes of sending fewer packets (Nagle's
-// algorithm).  The default is true (no delay), meaning that data is
-// sent as soon as possible after a Write.
-func (c *TCPConn) SetNoDelay(noDelay bool) error {
-	return &OpError{Op: "set", Net: c.fd.dir, Source: c.fd.laddr, Addr: c.fd.raddr, Err: syscall.EPLAN9}
-}
-
-// DialTCP connects to the remote address raddr on the network net,
-// which must be "tcp", "tcp4", or "tcp6".  If laddr is not nil, it is
-// used as the local address for the connection.
-func DialTCP(net string, laddr, raddr *TCPAddr) (*TCPConn, error) {
-	return dialTCP(net, laddr, raddr, noDeadline, noCancel)
+func (c *TCPConn) readFrom(r io.Reader) (int64, error) {
+	return genericReadFrom(c, r)
 }
 
 func dialTCP(net string, laddr, raddr *TCPAddr, deadline time.Time, cancel <-chan struct{}) (*TCPConn, error) {
@@ -118,10 +22,10 @@ func dialTCP(net string, laddr, raddr *TCPAddr, deadline time.Time, cancel <-cha
 	switch net {
 	case "tcp", "tcp4", "tcp6":
 	default:
-		return nil, &OpError{Op: "dial", Net: net, Source: laddr.opAddr(), Addr: raddr.opAddr(), Err: UnknownNetworkError(net)}
+		return nil, UnknownNetworkError(net)
 	}
 	if raddr == nil {
-		return nil, &OpError{Op: "dial", Net: net, Source: laddr.opAddr(), Addr: nil, Err: errMissingAddress}
+		return nil, errMissingAddress
 	}
 	fd, err := dialPlan9(net, laddr, raddr)
 	if err != nil {
@@ -130,101 +34,37 @@ func dialTCP(net string, laddr, raddr *TCPAddr, deadline time.Time, cancel <-cha
 	return newTCPConn(fd), nil
 }
 
-// TCPListener is a TCP network listener. Clients should typically
-// use variables of type Listener instead of assuming TCP.
-type TCPListener struct {
-	fd *netFD
-}
+func (ln *TCPListener) ok() bool { return ln != nil && ln.fd != nil && ln.fd.ctl != nil }
 
-// AcceptTCP accepts the next incoming call and returns the new
-// connection.
-func (l *TCPListener) AcceptTCP() (*TCPConn, error) {
-	if l == nil || l.fd == nil || l.fd.ctl == nil {
-		return nil, syscall.EINVAL
-	}
-	fd, err := l.fd.acceptPlan9()
+func (ln *TCPListener) accept() (*TCPConn, error) {
+	fd, err := ln.fd.acceptPlan9()
 	if err != nil {
 		return nil, err
 	}
 	return newTCPConn(fd), nil
 }
 
-// Accept implements the Accept method in the Listener interface; it
-// waits for the next call and returns a generic Conn.
-func (l *TCPListener) Accept() (Conn, error) {
-	if l == nil || l.fd == nil || l.fd.ctl == nil {
-		return nil, syscall.EINVAL
-	}
-	c, err := l.AcceptTCP()
-	if err != nil {
-		return nil, err
-	}
-	return c, nil
-}
-
-// Close stops listening on the TCP address.
-// Already Accepted connections are not closed.
-func (l *TCPListener) Close() error {
-	if l == nil || l.fd == nil || l.fd.ctl == nil {
-		return syscall.EINVAL
-	}
-	if _, err := l.fd.ctl.WriteString("hangup"); err != nil {
-		l.fd.ctl.Close()
-		return &OpError{Op: "close", Net: l.fd.dir, Source: nil, Addr: l.fd.laddr, Err: err}
-	}
-	err := l.fd.ctl.Close()
-	if err != nil {
-		err = &OpError{Op: "close", Net: l.fd.dir, Source: nil, Addr: l.fd.laddr, Err: err}
-	}
+func (ln *TCPListener) close() error {
+	if _, err := ln.fd.ctl.WriteString("hangup"); err != nil {
+		ln.fd.ctl.Close()
 		return err
-}
-
-// Addr returns the listener's network address, a *TCPAddr.
-// The Addr returned is shared by all invocations of Addr, so
-// do not modify it.
-func (l *TCPListener) Addr() Addr { return l.fd.laddr }
-
-// SetDeadline sets the deadline associated with the listener.
-// A zero time value disables the deadline.
-func (l *TCPListener) SetDeadline(t time.Time) error {
-	if l == nil || l.fd == nil || l.fd.ctl == nil {
-		return syscall.EINVAL
 	}
-	if err := l.fd.setDeadline(t); err != nil {
-		return &OpError{Op: "set", Net: l.fd.dir, Source: nil, Addr: l.fd.laddr, Err: err}
+	if err := ln.fd.ctl.Close(); err != nil {
+		return err
 	}
 	return nil
 }
 
-// File returns a copy of the underlying os.File, set to blocking
-// mode. It is the caller's responsibility to close f when finished.
-// Closing l does not affect f, and closing f does not affect l.
-//
-// The returned os.File's file descriptor is different from the
-// connection's. Attempting to change properties of the original
-// using this duplicate may or may not have the desired effect.
-func (l *TCPListener) File() (f *os.File, err error) {
-	f, err = l.dup()
+func (ln *TCPListener) file() (*os.File, error) {
+	f, err := ln.dup()
 	if err != nil {
-		err = &OpError{Op: "file", Net: l.fd.dir, Source: nil, Addr: l.fd.laddr, Err: err}
+		return nil, err
 	}
-	return
+	return f, nil
 }
 
-// ListenTCP announces on the TCP address laddr and returns a TCP
-// listener. Net must be "tcp", "tcp4", or "tcp6".  If laddr has a
-// port of 0, ListenTCP will choose an available port. The caller can
-// use the Addr method of TCPListener to retrieve the chosen address.
-func ListenTCP(net string, laddr *TCPAddr) (*TCPListener, error) {
-	switch net {
-	case "tcp", "tcp4", "tcp6":
-	default:
-		return nil, &OpError{Op: "listen", Net: net, Source: nil, Addr: laddr.opAddr(), Err: UnknownNetworkError(net)}
-	}
-	if laddr == nil {
-		laddr = &TCPAddr{}
-	}
-	fd, err := listenPlan9(net, laddr)
+func listenTCP(network string, laddr *TCPAddr) (*TCPListener, error) {
+	fd, err := listenPlan9(network, laddr)
 	if err != nil {
 		return nil, err
 	}

src/net/tcpsock_posix.go

@@ -40,131 +40,11 @@ func (a *TCPAddr) sockaddr(family int) (syscall.Sockaddr, error) {
 	return ipToSockaddr(family, a.IP, a.Port, a.Zone)
 }
 
-// TCPConn is an implementation of the Conn interface for TCP network
-// connections.
-type TCPConn struct {
-	conn
-}
-
-func newTCPConn(fd *netFD) *TCPConn {
-	c := &TCPConn{conn{fd}}
-	setNoDelay(c.fd, true)
-	return c
-}
-
-// ReadFrom implements the io.ReaderFrom ReadFrom method.
-func (c *TCPConn) ReadFrom(r io.Reader) (int64, error) {
+func (c *TCPConn) readFrom(r io.Reader) (int64, error) {
 	if n, err, handled := sendFile(c.fd, r); handled {
-		if err != nil && err != io.EOF {
-			err = &OpError{Op: "read", Net: c.fd.net, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}
-		}
-		return n, err
-	}
-	n, err := genericReadFrom(c, r)
-	if err != nil && err != io.EOF {
-		err = &OpError{Op: "read", Net: c.fd.net, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}
-	}
 		return n, err
-}
-
-// CloseRead shuts down the reading side of the TCP connection.
-// Most callers should just use Close.
-func (c *TCPConn) CloseRead() error {
-	if !c.ok() {
-		return syscall.EINVAL
-	}
-	err := c.fd.closeRead()
-	if err != nil {
-		err = &OpError{Op: "close", Net: c.fd.net, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}
-	}
-	return err
-}
-
-// CloseWrite shuts down the writing side of the TCP connection.
-// Most callers should just use Close.
-func (c *TCPConn) CloseWrite() error {
-	if !c.ok() {
-		return syscall.EINVAL
-	}
-	err := c.fd.closeWrite()
-	if err != nil {
-		err = &OpError{Op: "close", Net: c.fd.net, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}
-	}
-	return err
-}
-
-// SetLinger sets the behavior of Close on a connection which still
-// has data waiting to be sent or to be acknowledged.
-//
-// If sec < 0 (the default), the operating system finishes sending the
-// data in the background.
-//
-// If sec == 0, the operating system discards any unsent or
-// unacknowledged data.
-//
-// If sec > 0, the data is sent in the background as with sec < 0. On
-// some operating systems after sec seconds have elapsed any remaining
-// unsent data may be discarded.
-func (c *TCPConn) SetLinger(sec int) error {
-	if !c.ok() {
-		return syscall.EINVAL
-	}
-	if err := setLinger(c.fd, sec); err != nil {
-		return &OpError{Op: "set", Net: c.fd.net, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}
-	}
-	return nil
-}
-
-// SetKeepAlive sets whether the operating system should send
-// keepalive messages on the connection.
-func (c *TCPConn) SetKeepAlive(keepalive bool) error {
-	if !c.ok() {
-		return syscall.EINVAL
-	}
-	if err := setKeepAlive(c.fd, keepalive); err != nil {
-		return &OpError{Op: "set", Net: c.fd.net, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}
-	}
-	return nil
-}
-
-// SetKeepAlivePeriod sets period between keep alives.
-func (c *TCPConn) SetKeepAlivePeriod(d time.Duration) error {
-	if !c.ok() {
-		return syscall.EINVAL
 	}
-	if err := setKeepAlivePeriod(c.fd, d); err != nil {
-		return &OpError{Op: "set", Net: c.fd.net, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}
-	}
-	return nil
-}
-
-// SetNoDelay controls whether the operating system should delay
-// packet transmission in hopes of sending fewer packets (Nagle's
-// algorithm).  The default is true (no delay), meaning that data is
-// sent as soon as possible after a Write.
-func (c *TCPConn) SetNoDelay(noDelay bool) error {
-	if !c.ok() {
-		return syscall.EINVAL
-	}
-	if err := setNoDelay(c.fd, noDelay); err != nil {
-		return &OpError{Op: "set", Net: c.fd.net, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}
-	}
-	return nil
-}
-
-// DialTCP connects to the remote address raddr on the network net,
-// which must be "tcp", "tcp4", or "tcp6".  If laddr is not nil, it is
-// used as the local address for the connection.
-func DialTCP(net string, laddr, raddr *TCPAddr) (*TCPConn, error) {
-	switch net {
-	case "tcp", "tcp4", "tcp6":
-	default:
-		return nil, &OpError{Op: "dial", Net: net, Source: laddr.opAddr(), Addr: raddr.opAddr(), Err: UnknownNetworkError(net)}
-	}
-	if raddr == nil {
-		return nil, &OpError{Op: "dial", Net: net, Source: laddr.opAddr(), Addr: nil, Err: errMissingAddress}
-	}
-	return dialTCP(net, laddr, raddr, noDeadline, noCancel)
+	return genericReadFrom(c, r)
 }
 
 func dialTCP(net string, laddr, raddr *TCPAddr, deadline time.Time, cancel <-chan struct{}) (*TCPConn, error) {
@@ -202,7 +82,7 @@ func dialTCP(net string, laddr, raddr *TCPAddr, deadline time.Time, cancel <-cha
 	}
 
 	if err != nil {
-		return nil, &OpError{Op: "dial", Net: net, Source: laddr.opAddr(), Addr: raddr.opAddr(), Err: err}
+		return nil, err
 	}
 	return newTCPConn(fd), nil
 }
@@ -239,96 +119,32 @@ func spuriousENOTAVAIL(err error) bool {
 	return err == syscall.EADDRNOTAVAIL
 }
 
-// TCPListener is a TCP network listener. Clients should typically
-// use variables of type Listener instead of assuming TCP.
-type TCPListener struct {
-	fd *netFD
-}
+func (ln *TCPListener) ok() bool { return ln != nil && ln.fd != nil }
 
-// AcceptTCP accepts the next incoming call and returns the new
-// connection.
-func (l *TCPListener) AcceptTCP() (*TCPConn, error) {
-	if l == nil || l.fd == nil {
-		return nil, syscall.EINVAL
-	}
-	fd, err := l.fd.accept()
-	if err != nil {
-		return nil, &OpError{Op: "accept", Net: l.fd.net, Source: nil, Addr: l.fd.laddr, Err: err}
-	}
-	return newTCPConn(fd), nil
-}
-
-// Accept implements the Accept method in the Listener interface; it
-// waits for the next call and returns a generic Conn.
-func (l *TCPListener) Accept() (Conn, error) {
-	c, err := l.AcceptTCP()
+func (ln *TCPListener) accept() (*TCPConn, error) {
+	fd, err := ln.fd.accept()
 	if err != nil {
 		return nil, err
 	}
-	return c, nil
+	return newTCPConn(fd), nil
 }
 
-// Close stops listening on the TCP address.
-// Already Accepted connections are not closed.
-func (l *TCPListener) Close() error {
-	if l == nil || l.fd == nil {
-		return syscall.EINVAL
-	}
-	err := l.fd.Close()
-	if err != nil {
-		err = &OpError{Op: "close", Net: l.fd.net, Source: nil, Addr: l.fd.laddr, Err: err}
-	}
-	return err
+func (ln *TCPListener) close() error {
+	return ln.fd.Close()
 }
 
-// Addr returns the listener's network address, a *TCPAddr.
-// The Addr returned is shared by all invocations of Addr, so
-// do not modify it.
-func (l *TCPListener) Addr() Addr { return l.fd.laddr }
-
-// SetDeadline sets the deadline associated with the listener.
-// A zero time value disables the deadline.
-func (l *TCPListener) SetDeadline(t time.Time) error {
-	if l == nil || l.fd == nil {
-		return syscall.EINVAL
-	}
-	if err := l.fd.setDeadline(t); err != nil {
-		return &OpError{Op: "set", Net: l.fd.net, Source: nil, Addr: l.fd.laddr, Err: err}
-	}
-	return nil
-}
-
-// File returns a copy of the underlying os.File, set to blocking
-// mode. It is the caller's responsibility to close f when finished.
-// Closing l does not affect f, and closing f does not affect l.
-//
-// The returned os.File's file descriptor is different from the
-// connection's. Attempting to change properties of the original
-// using this duplicate may or may not have the desired effect.
-func (l *TCPListener) File() (f *os.File, err error) {
-	f, err = l.fd.dup()
+func (ln *TCPListener) file() (*os.File, error) {
+	f, err := ln.fd.dup()
 	if err != nil {
-		err = &OpError{Op: "file", Net: l.fd.net, Source: nil, Addr: l.fd.laddr, Err: err}
+		return nil, err
 	}
-	return
+	return f, nil
 }
 
-// ListenTCP announces on the TCP address laddr and returns a TCP
-// listener. Net must be "tcp", "tcp4", or "tcp6".  If laddr has a
-// port of 0, ListenTCP will choose an available port. The caller can
-// use the Addr method of TCPListener to retrieve the chosen address.
-func ListenTCP(net string, laddr *TCPAddr) (*TCPListener, error) {
-	switch net {
-	case "tcp", "tcp4", "tcp6":
-	default:
-		return nil, &OpError{Op: "listen", Net: net, Source: nil, Addr: laddr.opAddr(), Err: UnknownNetworkError(net)}
-	}
-	if laddr == nil {
-		laddr = &TCPAddr{}
-	}
-	fd, err := internetSocket(net, laddr, nil, noDeadline, syscall.SOCK_STREAM, 0, "listen", noCancel)
+func listenTCP(network string, laddr *TCPAddr) (*TCPListener, error) {
+	fd, err := internetSocket(network, laddr, nil, noDeadline, syscall.SOCK_STREAM, 0, "listen", noCancel)
 	if err != nil {
-		return nil, &OpError{Op: "listen", Net: net, Source: nil, Addr: laddr, Err: err}
+		return nil, err
 	}
 	return &TCPListener{fd}, nil
 }

src/net/tcpsockopt_plan9.go

@@ -7,9 +7,14 @@
 package net
 
 import (
+	"syscall"
 	"time"
 )
 
+func setNoDelay(fd *netFD, noDelay bool) error {
+	return syscall.EPLAN9
+}
+
 // Set keep alive period.
 func setKeepAlivePeriod(fd *netFD, d time.Duration) error {
 	cmd := "keepalive " + itoa(int(d/time.Millisecond))

src/net/udpsock_plan9.go

@@ -117,7 +117,11 @@ func (c *UDPConn) WriteMsgUDP(b, oob []byte, addr *UDPAddr) (n, oobn int, err er
 // which must be "udp", "udp4", or "udp6".  If laddr is not nil, it is
 // used as the local address for the connection.
 func DialUDP(net string, laddr, raddr *UDPAddr) (*UDPConn, error) {
-	return dialUDP(net, laddr, raddr, noDeadline)
+	c, err := dialUDP(net, laddr, raddr, noDeadline)
+	if err != nil {
+		return nil, &OpError{Op: "dial", Net: net, Source: laddr.opAddr(), Addr: raddr.opAddr(), Err: err}
+	}
+	return c, nil
 }
 
 func dialUDP(net string, laddr, raddr *UDPAddr, deadline time.Time) (*UDPConn, error) {
@@ -127,10 +131,10 @@ func dialUDP(net string, laddr, raddr *UDPAddr, deadline time.Time) (*UDPConn, e
 	switch net {
 	case "udp", "udp4", "udp6":
 	default:
-		return nil, &OpError{Op: "dial", Net: net, Source: laddr.opAddr(), Addr: raddr.opAddr(), Err: UnknownNetworkError(net)}
+		return nil, UnknownNetworkError(net)
 	}
 	if raddr == nil {
-		return nil, &OpError{Op: "dial", Net: net, Source: laddr.opAddr(), Addr: nil, Err: errMissingAddress}
+		return nil, errMissingAddress
 	}
 	fd, err := dialPlan9(net, laddr, raddr)
 	if err != nil {

src/net/udpsock_posix.go

@@ -185,13 +185,17 @@ func DialUDP(net string, laddr, raddr *UDPAddr) (*UDPConn, error) {
 	if raddr == nil {
 		return nil, &OpError{Op: "dial", Net: net, Source: laddr.opAddr(), Addr: nil, Err: errMissingAddress}
 	}
-	return dialUDP(net, laddr, raddr, noDeadline)
+	c, err := dialUDP(net, laddr, raddr, noDeadline)
+	if err != nil {
+		return nil, &OpError{Op: "dial", Net: net, Source: laddr.opAddr(), Addr: raddr.opAddr(), Err: err}
+	}
+	return c, nil
 }
 
 func dialUDP(net string, laddr, raddr *UDPAddr, deadline time.Time) (*UDPConn, error) {
 	fd, err := internetSocket(net, laddr, raddr, deadline, syscall.SOCK_DGRAM, 0, "dial", noCancel)
 	if err != nil {
-		return nil, &OpError{Op: "dial", Net: net, Source: laddr.opAddr(), Addr: raddr.opAddr(), Err: err}
+		return nil, err
 	}
 	return newUDPConn(fd), nil
 }

src/net/unixsock_posix.go

@@ -258,13 +258,17 @@ func DialUnix(net string, laddr, raddr *UnixAddr) (*UnixConn, error) {
 	default:
 		return nil, &OpError{Op: "dial", Net: net, Source: laddr.opAddr(), Addr: raddr.opAddr(), Err: UnknownNetworkError(net)}
 	}
-	return dialUnix(net, laddr, raddr, noDeadline)
+	c, err := dialUnix(net, laddr, raddr, noDeadline)
+	if err != nil {
+		return nil, &OpError{Op: "dial", Net: net, Source: laddr.opAddr(), Addr: raddr.opAddr(), Err: err}
+	}
+	return c, nil
 }
 
 func dialUnix(net string, laddr, raddr *UnixAddr, deadline time.Time) (*UnixConn, error) {
 	fd, err := unixSocket(net, laddr, raddr, "dial", deadline)
 	if err != nil {
-		return nil, &OpError{Op: "dial", Net: net, Source: laddr.opAddr(), Addr: raddr.opAddr(), Err: err}
+		return nil, err
 	}
 	return newUnixConn(fd), nil
 }

src/runtime/trace/trace_stack_test.go

@@ -235,7 +235,7 @@ func TestTraceSymbolize(t *testing.T) {
 		want = append(want, []eventDesc{
 			{trace.EvGoBlockNet, []frame{
 				{"net.(*netFD).accept", 0},
-				{"net.(*TCPListener).AcceptTCP", 0},
+				{"net.(*TCPListener).accept", 0},
 				{"net.(*TCPListener).Accept", 0},
 				{"runtime/trace_test.TestTraceSymbolize.func10", 86},
 			}},