Check in gVisor.

PiperOrigin-RevId: 194583126
Change-Id: Ica1d8821a90f74e7e745962d71801c598c652463

1 files changed, 605 insertions, 0 deletions

diff --git a/pkg/tcpip/adapters/gonet/gonet.go b/pkg/tcpip/adapters/gonet/gonet.go
new file mode 100644
index 000000000..96a2d670d
--- /dev/null
+++ b/pkg/tcpip/adapters/gonet/gonet.go
@@ -0,0 +1,605 @@
+// Copyright 2016 The Netstack Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package gonet provides a Go net package compatible wrapper for a tcpip stack.
+package gonet
+
+import (
+	"errors"
+	"io"
+	"net"
+	"sync"
+	"time"
+
+	"gvisor.googlesource.com/gvisor/pkg/tcpip"
+	"gvisor.googlesource.com/gvisor/pkg/tcpip/buffer"
+	"gvisor.googlesource.com/gvisor/pkg/tcpip/stack"
+	"gvisor.googlesource.com/gvisor/pkg/tcpip/transport/tcp"
+	"gvisor.googlesource.com/gvisor/pkg/tcpip/transport/udp"
+	"gvisor.googlesource.com/gvisor/pkg/waiter"
+)
+
+var errCanceled = errors.New("operation canceled")
+
+// timeoutError is how the net package reports timeouts.
+type timeoutError struct{}
+
+func (e *timeoutError) Error() string   { return "i/o timeout" }
+func (e *timeoutError) Timeout() bool   { return true }
+func (e *timeoutError) Temporary() bool { return true }
+
+// A Listener is a wrapper around a tcpip endpoint that implements
+// net.Listener.
+type Listener struct {
+	stack  *stack.Stack
+	ep     tcpip.Endpoint
+	wq     *waiter.Queue
+	cancel chan struct{}
+}
+
+// NewListener creates a new Listener.
+func NewListener(s *stack.Stack, addr tcpip.FullAddress, network tcpip.NetworkProtocolNumber) (*Listener, error) {
+	// Create TCP endpoint, bind it, then start listening.
+	var wq waiter.Queue
+	ep, err := s.NewEndpoint(tcp.ProtocolNumber, network, &wq)
+	if err != nil {
+		return nil, errors.New(err.String())
+	}
+
+	if err := ep.Bind(addr, nil); err != nil {
+		ep.Close()
+		return nil, &net.OpError{
+			Op:   "bind",
+			Net:  "tcp",
+			Addr: fullToTCPAddr(addr),
+			Err:  errors.New(err.String()),
+		}
+	}
+
+	if err := ep.Listen(10); err != nil {
+		ep.Close()
+		return nil, &net.OpError{
+			Op:   "listen",
+			Net:  "tcp",
+			Addr: fullToTCPAddr(addr),
+			Err:  errors.New(err.String()),
+		}
+	}
+
+	return &Listener{
+		stack:  s,
+		ep:     ep,
+		wq:     &wq,
+		cancel: make(chan struct{}),
+	}, nil
+}
+
+// Close implements net.Listener.Close.
+func (l *Listener) Close() error {
+	l.ep.Close()
+	return nil
+}
+
+// Shutdown stops the HTTP server.
+func (l *Listener) Shutdown() {
+	l.ep.Shutdown(tcpip.ShutdownWrite | tcpip.ShutdownRead)
+	close(l.cancel) // broadcast cancellation
+}
+
+// Addr implements net.Listener.Addr.
+func (l *Listener) Addr() net.Addr {
+	a, err := l.ep.GetLocalAddress()
+	if err != nil {
+		return nil
+	}
+	return fullToTCPAddr(a)
+}
+
+type deadlineTimer struct {
+	// mu protects the fields below.
+	mu sync.Mutex
+
+	readTimer     *time.Timer
+	readCancelCh  chan struct{}
+	writeTimer    *time.Timer
+	writeCancelCh chan struct{}
+}
+
+func (d *deadlineTimer) init() {
+	d.readCancelCh = make(chan struct{})
+	d.writeCancelCh = make(chan struct{})
+}
+
+func (d *deadlineTimer) readCancel() <-chan struct{} {
+	d.mu.Lock()
+	c := d.readCancelCh
+	d.mu.Unlock()
+	return c
+}
+func (d *deadlineTimer) writeCancel() <-chan struct{} {
+	d.mu.Lock()
+	c := d.writeCancelCh
+	d.mu.Unlock()
+	return c
+}
+
+// setDeadline contains the shared logic for setting a deadline.
+//
+// cancelCh and timer must be pointers to deadlineTimer.readCancelCh and
+// deadlineTimer.readTimer or deadlineTimer.writeCancelCh and
+// deadlineTimer.writeTimer.
+//
+// setDeadline must only be called while holding d.mu.
+func (d *deadlineTimer) setDeadline(cancelCh *chan struct{}, timer **time.Timer, t time.Time) {
+	if *timer != nil && !(*timer).Stop() {
+		*cancelCh = make(chan struct{})
+	}
+
+	// Create a new channel if we already closed it due to setting an already
+	// expired time. We won't race with the timer because we already handled
+	// that above.
+	select {
+	case <-*cancelCh:
+		*cancelCh = make(chan struct{})
+	default:
+	}
+
+	// "A zero value for t means I/O operations will not time out."
+	// - net.Conn.SetDeadline
+	if t.IsZero() {
+		return
+	}
+
+	timeout := t.Sub(time.Now())
+	if timeout <= 0 {
+		close(*cancelCh)
+		return
+	}
+
+	// Timer.Stop returns whether or not the AfterFunc has started, but
+	// does not indicate whether or not it has completed. Make a copy of
+	// the cancel channel to prevent this code from racing with the next
+	// call of setDeadline replacing *cancelCh.
+	ch := *cancelCh
+	*timer = time.AfterFunc(timeout, func() {
+		close(ch)
+	})
+}
+
+// SetReadDeadline implements net.Conn.SetReadDeadline and
+// net.PacketConn.SetReadDeadline.
+func (d *deadlineTimer) SetReadDeadline(t time.Time) error {
+	d.mu.Lock()
+	d.setDeadline(&d.readCancelCh, &d.readTimer, t)
+	d.mu.Unlock()
+	return nil
+}
+
+// SetWriteDeadline implements net.Conn.SetWriteDeadline and
+// net.PacketConn.SetWriteDeadline.
+func (d *deadlineTimer) SetWriteDeadline(t time.Time) error {
+	d.mu.Lock()
+	d.setDeadline(&d.writeCancelCh, &d.writeTimer, t)
+	d.mu.Unlock()
+	return nil
+}
+
+// SetDeadline implements net.Conn.SetDeadline and net.PacketConn.SetDeadline.
+func (d *deadlineTimer) SetDeadline(t time.Time) error {
+	d.mu.Lock()
+	d.setDeadline(&d.readCancelCh, &d.readTimer, t)
+	d.setDeadline(&d.writeCancelCh, &d.writeTimer, t)
+	d.mu.Unlock()
+	return nil
+}
+
+// A Conn is a wrapper around a tcpip.Endpoint that implements the net.Conn
+// interface.
+type Conn struct {
+	deadlineTimer
+
+	wq *waiter.Queue
+	ep tcpip.Endpoint
+
+	// readMu serializes reads and implicitly protects read.
+	//
+	// Lock ordering:
+	// If both readMu and deadlineTimer.mu are to be used in a single
+	// request, readMu must be acquired before deadlineTimer.mu.
+	readMu sync.Mutex
+
+	// read contains bytes that have been read from the endpoint,
+	// but haven't yet been returned.
+	read buffer.View
+}
+
+// NewConn creates a new Conn.
+func NewConn(wq *waiter.Queue, ep tcpip.Endpoint) *Conn {
+	c := &Conn{
+		wq: wq,
+		ep: ep,
+	}
+	c.deadlineTimer.init()
+	return c
+}
+
+// Accept implements net.Conn.Accept.
+func (l *Listener) Accept() (net.Conn, error) {
+	n, wq, err := l.ep.Accept()
+
+	if err == tcpip.ErrWouldBlock {
+		// Create wait queue entry that notifies a channel.
+		waitEntry, notifyCh := waiter.NewChannelEntry(nil)
+		l.wq.EventRegister(&waitEntry, waiter.EventIn)
+		defer l.wq.EventUnregister(&waitEntry)
+
+		for {
+			n, wq, err = l.ep.Accept()
+
+			if err != tcpip.ErrWouldBlock {
+				break
+			}
+
+			select {
+			case <-l.cancel:
+				return nil, errCanceled
+			case <-notifyCh:
+			}
+		}
+	}
+
+	if err != nil {
+		return nil, &net.OpError{
+			Op:   "accept",
+			Net:  "tcp",
+			Addr: l.Addr(),
+			Err:  errors.New(err.String()),
+		}
+	}
+
+	return NewConn(wq, n), nil
+}
+
+type opErrorer interface {
+	newOpError(op string, err error) *net.OpError
+}
+
+// commonRead implements the common logic between net.Conn.Read and
+// net.PacketConn.ReadFrom.
+func commonRead(ep tcpip.Endpoint, wq *waiter.Queue, deadline <-chan struct{}, addr *tcpip.FullAddress, errorer opErrorer) ([]byte, error) {
+	read, err := ep.Read(addr)
+
+	if err == tcpip.ErrWouldBlock {
+		// Create wait queue entry that notifies a channel.
+		waitEntry, notifyCh := waiter.NewChannelEntry(nil)
+		wq.EventRegister(&waitEntry, waiter.EventIn)
+		defer wq.EventUnregister(&waitEntry)
+		for {
+			read, err = ep.Read(addr)
+			if err != tcpip.ErrWouldBlock {
+				break
+			}
+			select {
+			case <-deadline:
+				return nil, errorer.newOpError("read", &timeoutError{})
+			case <-notifyCh:
+			}
+		}
+	}
+
+	if err == tcpip.ErrClosedForReceive {
+		return nil, io.EOF
+	}
+
+	if err != nil {
+		return nil, errorer.newOpError("read", errors.New(err.String()))
+	}
+
+	return read, nil
+}
+
+// Read implements net.Conn.Read.
+func (c *Conn) Read(b []byte) (int, error) {
+	c.readMu.Lock()
+	defer c.readMu.Unlock()
+
+	deadline := c.readCancel()
+
+	// Check if deadline has already expired.
+	select {
+	case <-deadline:
+		return 0, c.newOpError("read", &timeoutError{})
+	default:
+	}
+
+	if len(c.read) == 0 {
+		var err error
+		c.read, err = commonRead(c.ep, c.wq, deadline, nil, c)
+		if err != nil {
+			return 0, err
+		}
+	}
+
+	n := copy(b, c.read)
+	c.read.TrimFront(n)
+	if len(c.read) == 0 {
+		c.read = nil
+	}
+	return n, nil
+}
+
+// Write implements net.Conn.Write.
+func (c *Conn) Write(b []byte) (int, error) {
+	deadline := c.writeCancel()
+
+	// Check if deadlineTimer has already expired.
+	select {
+	case <-deadline:
+		return 0, c.newOpError("write", &timeoutError{})
+	default:
+	}
+
+	v := buffer.NewView(len(b))
+	copy(v, b)
+
+	// We must handle two soft failure conditions simultaneously:
+	//  1. Write may write nothing and return tcpip.ErrWouldBlock.
+	//     If this happens, we need to register for notifications if we have
+	//     not already and wait to try again.
+	//  2. Write may write fewer than the full number of bytes and return
+	//     without error. In this case we need to try writing the remaining
+	//     bytes again. I do not need to register for notifications.
+	//
+	// What is more, these two soft failure conditions can be interspersed.
+	// There is no guarantee that all of the condition #1s will occur before
+	// all of the condition #2s or visa-versa.
+	var (
+		err      *tcpip.Error
+		nbytes   int
+		reg      bool
+		notifyCh chan struct{}
+	)
+	for nbytes < len(b) && (err == tcpip.ErrWouldBlock || err == nil) {
+		if err == tcpip.ErrWouldBlock {
+			if !reg {
+				// Only register once.
+				reg = true
+
+				// Create wait queue entry that notifies a channel.
+				var waitEntry waiter.Entry
+				waitEntry, notifyCh = waiter.NewChannelEntry(nil)
+				c.wq.EventRegister(&waitEntry, waiter.EventOut)
+				defer c.wq.EventUnregister(&waitEntry)
+			} else {
+				// Don't wait immediately after registration in case more data
+				// became available between when we last checked and when we setup
+				// the notification.
+				select {
+				case <-deadline:
+					return nbytes, c.newOpError("write", &timeoutError{})
+				case <-notifyCh:
+				}
+			}
+		}
+
+		var n uintptr
+		n, err = c.ep.Write(tcpip.SlicePayload(v), tcpip.WriteOptions{})
+		nbytes += int(n)
+		v.TrimFront(int(n))
+	}
+
+	if err == nil {
+		return nbytes, nil
+	}
+
+	return nbytes, c.newOpError("write", errors.New(err.String()))
+}
+
+// Close implements net.Conn.Close.
+func (c *Conn) Close() error {
+	c.ep.Close()
+	return nil
+}
+
+// LocalAddr implements net.Conn.LocalAddr.
+func (c *Conn) LocalAddr() net.Addr {
+	a, err := c.ep.GetLocalAddress()
+	if err != nil {
+		return nil
+	}
+	return fullToTCPAddr(a)
+}
+
+// RemoteAddr implements net.Conn.RemoteAddr.
+func (c *Conn) RemoteAddr() net.Addr {
+	a, err := c.ep.GetRemoteAddress()
+	if err != nil {
+		return nil
+	}
+	return fullToTCPAddr(a)
+}
+
+func (c *Conn) newOpError(op string, err error) *net.OpError {
+	return &net.OpError{
+		Op:     op,
+		Net:    "tcp",
+		Source: c.LocalAddr(),
+		Addr:   c.RemoteAddr(),
+		Err:    err,
+	}
+}
+
+func fullToTCPAddr(addr tcpip.FullAddress) *net.TCPAddr {
+	return &net.TCPAddr{IP: net.IP(addr.Addr), Port: int(addr.Port)}
+}
+
+func fullToUDPAddr(addr tcpip.FullAddress) *net.UDPAddr {
+	return &net.UDPAddr{IP: net.IP(addr.Addr), Port: int(addr.Port)}
+}
+
+// DialTCP creates a new TCP Conn connected to the specified address.
+func DialTCP(s *stack.Stack, addr tcpip.FullAddress, network tcpip.NetworkProtocolNumber) (*Conn, error) {
+	// Create TCP endpoint, then connect.
+	var wq waiter.Queue
+	ep, err := s.NewEndpoint(tcp.ProtocolNumber, network, &wq)
+	if err != nil {
+		return nil, errors.New(err.String())
+	}
+
+	// Create wait queue entry that notifies a channel.
+	//
+	// We do this unconditionally as Connect will always return an error.
+	waitEntry, notifyCh := waiter.NewChannelEntry(nil)
+	wq.EventRegister(&waitEntry, waiter.EventOut)
+	defer wq.EventUnregister(&waitEntry)
+
+	err = ep.Connect(addr)
+	if err == tcpip.ErrConnectStarted {
+		<-notifyCh
+		err = ep.GetSockOpt(tcpip.ErrorOption{})
+	}
+	if err != nil {
+		ep.Close()
+		return nil, &net.OpError{
+			Op:   "connect",
+			Net:  "tcp",
+			Addr: fullToTCPAddr(addr),
+			Err:  errors.New(err.String()),
+		}
+	}
+
+	return NewConn(&wq, ep), nil
+}
+
+// A PacketConn is a wrapper around a tcpip endpoint that implements
+// net.PacketConn.
+type PacketConn struct {
+	deadlineTimer
+
+	stack *stack.Stack
+	ep    tcpip.Endpoint
+	wq    *waiter.Queue
+}
+
+// NewPacketConn creates a new PacketConn.
+func NewPacketConn(s *stack.Stack, addr tcpip.FullAddress, network tcpip.NetworkProtocolNumber) (*PacketConn, error) {
+	// Create UDP endpoint and bind it.
+	var wq waiter.Queue
+	ep, err := s.NewEndpoint(udp.ProtocolNumber, network, &wq)
+	if err != nil {
+		return nil, errors.New(err.String())
+	}
+
+	if err := ep.Bind(addr, nil); err != nil {
+		ep.Close()
+		return nil, &net.OpError{
+			Op:   "bind",
+			Net:  "udp",
+			Addr: fullToUDPAddr(addr),
+			Err:  errors.New(err.String()),
+		}
+	}
+
+	c := &PacketConn{
+		stack: s,
+		ep:    ep,
+		wq:    &wq,
+	}
+	c.deadlineTimer.init()
+	return c, nil
+}
+
+func (c *PacketConn) newOpError(op string, err error) *net.OpError {
+	return c.newRemoteOpError(op, nil, err)
+}
+
+func (c *PacketConn) newRemoteOpError(op string, remote net.Addr, err error) *net.OpError {
+	return &net.OpError{
+		Op:     op,
+		Net:    "udp",
+		Source: c.LocalAddr(),
+		Addr:   remote,
+		Err:    err,
+	}
+}
+
+// ReadFrom implements net.PacketConn.ReadFrom.
+func (c *PacketConn) ReadFrom(b []byte) (int, net.Addr, error) {
+	deadline := c.readCancel()
+
+	// Check if deadline has already expired.
+	select {
+	case <-deadline:
+		return 0, nil, c.newOpError("read", &timeoutError{})
+	default:
+	}
+
+	var addr tcpip.FullAddress
+	read, err := commonRead(c.ep, c.wq, deadline, &addr, c)
+	if err != nil {
+		return 0, nil, err
+	}
+
+	return copy(b, read), fullToUDPAddr(addr), nil
+}
+
+// WriteTo implements net.PacketConn.WriteTo.
+func (c *PacketConn) WriteTo(b []byte, addr net.Addr) (int, error) {
+	deadline := c.writeCancel()
+
+	// Check if deadline has already expired.
+	select {
+	case <-deadline:
+		return 0, c.newRemoteOpError("write", addr, &timeoutError{})
+	default:
+	}
+
+	ua := addr.(*net.UDPAddr)
+	fullAddr := tcpip.FullAddress{Addr: tcpip.Address(ua.IP), Port: uint16(ua.Port)}
+
+	v := buffer.NewView(len(b))
+	copy(v, b)
+
+	wopts := tcpip.WriteOptions{To: &fullAddr}
+	n, err := c.ep.Write(tcpip.SlicePayload(v), wopts)
+
+	if err == tcpip.ErrWouldBlock {
+		// Create wait queue entry that notifies a channel.
+		waitEntry, notifyCh := waiter.NewChannelEntry(nil)
+		c.wq.EventRegister(&waitEntry, waiter.EventOut)
+		defer c.wq.EventUnregister(&waitEntry)
+		for {
+			n, err = c.ep.Write(tcpip.SlicePayload(v), wopts)
+			if err != tcpip.ErrWouldBlock {
+				break
+			}
+			select {
+			case <-deadline:
+				return int(n), c.newRemoteOpError("write", addr, &timeoutError{})
+			case <-notifyCh:
+			}
+		}
+	}
+
+	if err == nil {
+		return int(n), nil
+	}
+
+	return int(n), c.newRemoteOpError("write", addr, errors.New(err.String()))
+}
+
+// Close implements net.PacketConn.Close.
+func (c *PacketConn) Close() error {
+	c.ep.Close()
+	return nil
+}
+
+// LocalAddr implements net.PacketConn.LocalAddr.
+func (c *PacketConn) LocalAddr() net.Addr {
+	a, err := c.ep.GetLocalAddress()
+	if err != nil {
+		return nil
+	}
+	return fullToUDPAddr(a)
+}