netstack: tcp socket connected state S/R support.

PiperOrigin-RevId: 203958972
Change-Id: Ia6fe16547539296d48e2c6731edacdd96bd6e93c

1 files changed, 57 insertions, 15 deletions

diff --git a/pkg/tcpip/transport/tcp/endpoint.go b/pkg/tcpip/transport/tcp/endpoint.go
index cb105b863..8b9a81f6a 100644
--- a/pkg/tcpip/transport/tcp/endpoint.go
+++ b/pkg/tcpip/transport/tcp/endpoint.go
@@ -80,7 +80,7 @@ type endpoint struct {
 	// change throughout the lifetime of the endpoint.
 	stack       *stack.Stack `state:"manual"`
 	netProto    tcpip.NetworkProtocolNumber
-	waiterQueue *waiter.Queue
+	waiterQueue *waiter.Queue `state:"wait"`
 
 	// lastError represents the last error that the endpoint reported;
 	// access to it is protected by the following mutex.
@@ -95,8 +95,8 @@ type endpoint struct {
 	// to indicate to users that no more data is coming.
 	//
 	// rcvListMu can be taken after the endpoint mu below.
-	rcvListMu  sync.Mutex `state:"nosave"`
-	rcvList    segmentList
+	rcvListMu  sync.Mutex  `state:"nosave"`
+	rcvList    segmentList `state:"wait"`
 	rcvClosed  bool
 	rcvBufSize int
 	rcvBufUsed int
@@ -104,8 +104,8 @@ type endpoint struct {
 	// The following fields are protected by the mutex.
 	mu                sync.RWMutex `state:"nosave"`
 	id                stack.TransportEndpointID
-	state             endpointState
-	isPortReserved    bool `state:"manual"`
+	state             endpointState `state:".(endpointState)"`
+	isPortReserved    bool          `state:"manual"`
 	isRegistered      bool
 	boundNICID        tcpip.NICID `state:"manual"`
 	route             stack.Route `state:"manual"`
@@ -131,7 +131,7 @@ type endpoint struct {
 	// workerCleanup specifies if the worker goroutine must perform cleanup
 	// before exitting. This can only be set to true when workerRunning is
 	// also true, and they're both protected by the mutex.
-	workerCleanup bool `state:"zerovalue"`
+	workerCleanup bool
 
 	// sendTSOk is used to indicate when the TS Option has been negotiated.
 	// When sendTSOk is true every non-RST segment should carry a TS as per
@@ -166,7 +166,7 @@ type endpoint struct {
 	// segmentQueue is used to hand received segments to the protocol
 	// goroutine. Segments are queued as long as the queue is not full,
 	// and dropped when it is.
-	segmentQueue segmentQueue `state:"zerovalue"`
+	segmentQueue segmentQueue `state:"wait"`
 
 	// The following fields are used to manage the send buffer. When
 	// segments are ready to be sent, they are added to sndQueue and the
@@ -179,7 +179,7 @@ type endpoint struct {
 	sndBufUsed    int
 	sndClosed     bool
 	sndBufInQueue seqnum.Size
-	sndQueue      segmentList
+	sndQueue      segmentList `state:"wait"`
 	sndWaker      sleep.Waker `state:"manual"`
 	sndCloseWaker sleep.Waker `state:"manual"`
 
@@ -201,17 +201,21 @@ type endpoint struct {
 
 	// notifyFlags is a bitmask of flags used to indicate to the protocol
 	// goroutine what it was notified; this is only accessed atomically.
-	notifyFlags uint32 `state:"zerovalue"`
+	notifyFlags uint32 `state:"nosave"`
 
 	// acceptedChan is used by a listening endpoint protocol goroutine to
 	// send newly accepted connections to the endpoint so that they can be
 	// read by Accept() calls.
-	acceptedChan chan *endpoint `state:".(endpointChan)"`
+	acceptedChan chan *endpoint `state:"manual"`
+
+	// acceptedEndpoints is only used to save / restore the channel buffer.
+	// FIXME
+	acceptedEndpoints []*endpoint
 
 	// The following are only used from the protocol goroutine, and
 	// therefore don't need locks to protect them.
-	rcv *receiver
-	snd *sender
+	rcv *receiver `state:"wait"`
+	snd *sender   `state:"wait"`
 
 	// The goroutine drain completion notification channel.
 	drainDone chan struct{} `state:"nosave"`
@@ -224,6 +228,7 @@ type endpoint struct {
 	probe stack.TCPProbeFunc `state:"nosave"`
 
 	// The following are only used to assist the restore run to re-connect.
+	bindAddress       tcpip.Address
 	connectingAddress tcpip.Address
 }
 
@@ -357,6 +362,7 @@ func (e *endpoint) Close() {
 
 	// Either perform the local cleanup or kick the worker to make sure it
 	// knows it needs to cleanup.
+	tcpip.AddDanglingEndpoint(e)
 	if !e.workerRunning {
 		e.cleanupLocked()
 	} else {
@@ -376,9 +382,12 @@ func (e *endpoint) cleanupLocked() {
 	if e.acceptedChan != nil {
 		close(e.acceptedChan)
 		for n := range e.acceptedChan {
+			n.mu.Lock()
 			n.resetConnectionLocked(tcpip.ErrConnectionAborted)
+			n.mu.Unlock()
 			n.Close()
 		}
+		e.acceptedChan = nil
 	}
 	e.workerCleanup = false
 
@@ -387,6 +396,7 @@ func (e *endpoint) cleanupLocked() {
 	}
 
 	e.route.Release()
+	tcpip.DeleteDanglingEndpoint(e)
 }
 
 // Read reads data from the endpoint.
@@ -801,6 +811,16 @@ func (e *endpoint) checkV4Mapped(addr *tcpip.FullAddress) (tcpip.NetworkProtocol
 
 // Connect connects the endpoint to its peer.
 func (e *endpoint) Connect(addr tcpip.FullAddress) *tcpip.Error {
+	return e.connect(addr, true, true)
+}
+
+// connect connects the endpoint to its peer. In the normal non-S/R case, the
+// new connection is expected to run the main goroutine and perform handshake.
+// In restore of previously connected endpoints, both ends will be passively
+// created (so no new handshaking is done); for stack-accepted connections not
+// yet accepted by the app, they are restored without running the main goroutine
+// here.
+func (e *endpoint) connect(addr tcpip.FullAddress, handshake bool, run bool) *tcpip.Error {
 	e.mu.Lock()
 	defer e.mu.Unlock()
 
@@ -912,9 +932,27 @@ func (e *endpoint) Connect(addr tcpip.FullAddress) *tcpip.Error {
 	e.boundNICID = nicid
 	e.effectiveNetProtos = netProtos
 	e.connectingAddress = connectingAddr
-	e.workerRunning = true
 
-	go e.protocolMainLoop(false) // S/R-SAFE: will be drained before save.
+	// Connect in the restore phase does not perform handshake. Restore its
+	// connection setting here.
+	if !handshake {
+		e.segmentQueue.mu.Lock()
+		for _, l := range []segmentList{e.segmentQueue.list, e.sndQueue, e.snd.writeList} {
+			for s := l.Front(); s != nil; s = s.Next() {
+				s.id = e.id
+				s.route = r.Clone()
+				e.sndWaker.Assert()
+			}
+		}
+		e.segmentQueue.mu.Unlock()
+		e.snd.updateMaxPayloadSize(int(e.route.MTU()), 0)
+		e.state = stateConnected
+	}
+
+	if run {
+		e.workerRunning = true
+		go e.protocolMainLoop(handshake) // S/R-SAFE: will be drained before save.
+	}
 
 	return tcpip.ErrConnectStarted
 }
@@ -999,6 +1037,9 @@ func (e *endpoint) Listen(backlog int) *tcpip.Error {
 		if len(e.acceptedChan) > backlog {
 			return tcpip.ErrInvalidEndpointState
 		}
+		if cap(e.acceptedChan) == backlog {
+			return nil
+		}
 		origChan := e.acceptedChan
 		e.acceptedChan = make(chan *endpoint, backlog)
 		close(origChan)
@@ -1036,7 +1077,7 @@ func (e *endpoint) Listen(backlog int) *tcpip.Error {
 func (e *endpoint) startAcceptedLoop(waiterQueue *waiter.Queue) {
 	e.waiterQueue = waiterQueue
 	e.workerRunning = true
-	go e.protocolMainLoop(true) // S/R-FIXME
+	go e.protocolMainLoop(false) // S/R-SAFE: drained on save.
 }
 
 // Accept returns a new endpoint if a peer has established a connection
@@ -1077,6 +1118,7 @@ func (e *endpoint) Bind(addr tcpip.FullAddress, commit func() *tcpip.Error) (ret
 		return tcpip.ErrAlreadyBound
 	}
 
+	e.bindAddress = addr.Addr
 	netProto, err := e.checkV4Mapped(&addr)
 	if err != nil {
 		return err