diff options
Diffstat (limited to 'pkg/tcpip/transport/tcp/connect.go')
| -rw-r--r-- | pkg/tcpip/transport/tcp/connect.go | 413 |
1 files changed, 262 insertions, 151 deletions
diff --git a/pkg/tcpip/transport/tcp/connect.go b/pkg/tcpip/transport/tcp/connect.go index 4206db8b6..4e3c5419c 100644 --- a/pkg/tcpip/transport/tcp/connect.go +++ b/pkg/tcpip/transport/tcp/connect.go @@ -16,11 +16,11 @@ package tcp import ( "encoding/binary" - "sync" "time" "gvisor.dev/gvisor/pkg/rand" "gvisor.dev/gvisor/pkg/sleep" + "gvisor.dev/gvisor/pkg/sync" "gvisor.dev/gvisor/pkg/tcpip" "gvisor.dev/gvisor/pkg/tcpip/buffer" "gvisor.dev/gvisor/pkg/tcpip/hash/jenkins" @@ -190,7 +190,7 @@ func (h *handshake) resetToSynRcvd(iss seqnum.Value, irs seqnum.Value, opts *hea h.mss = opts.MSS h.sndWndScale = opts.WS h.ep.mu.Lock() - h.ep.state = StateSynRecv + h.ep.setEndpointState(StateSynRecv) h.ep.mu.Unlock() } @@ -218,6 +218,14 @@ func (h *handshake) synSentState(s *segment) *tcpip.Error { // acceptable if the ack field acknowledges the SYN. if s.flagIsSet(header.TCPFlagRst) { if s.flagIsSet(header.TCPFlagAck) && s.ackNumber == h.iss+1 { + // RFC 793, page 67, states that "If the RST bit is set [and] If the ACK + // was acceptable then signal the user "error: connection reset", drop + // the segment, enter CLOSED state, delete TCB, and return." + h.ep.mu.Lock() + h.ep.workerCleanup = true + h.ep.mu.Unlock() + // Although the RFC above calls out ECONNRESET, Linux actually returns + // ECONNREFUSED here so we do as well. return tcpip.ErrConnectionRefused } return nil @@ -252,6 +260,11 @@ func (h *handshake) synSentState(s *segment) *tcpip.Error { // and the handshake is completed. if s.flagIsSet(header.TCPFlagAck) { h.state = handshakeCompleted + + h.ep.mu.Lock() + h.ep.transitionToStateEstablishedLocked(h) + h.ep.mu.Unlock() + h.ep.sendRaw(buffer.VectorisedView{}, header.TCPFlagAck, h.iss+1, h.ackNum, h.rcvWnd>>h.effectiveRcvWndScale()) return nil } @@ -261,14 +274,14 @@ func (h *handshake) synSentState(s *segment) *tcpip.Error { // SYN-RCVD state. h.state = handshakeSynRcvd h.ep.mu.Lock() - h.ep.state = StateSynRecv ttl := h.ep.ttl + h.ep.setEndpointState(StateSynRecv) h.ep.mu.Unlock() synOpts := header.TCPSynOptions{ WS: int(h.effectiveRcvWndScale()), TS: rcvSynOpts.TS, TSVal: h.ep.timestamp(), - TSEcr: h.ep.recentTS, + TSEcr: h.ep.recentTimestamp(), // We only send SACKPermitted if the other side indicated it // permits SACK. This is not explicitly defined in the RFC but @@ -328,7 +341,7 @@ func (h *handshake) synRcvdState(s *segment) *tcpip.Error { WS: h.rcvWndScale, TS: h.ep.sendTSOk, TSVal: h.ep.timestamp(), - TSEcr: h.ep.recentTS, + TSEcr: h.ep.recentTimestamp(), SACKPermitted: h.ep.sackPermitted, MSS: h.ep.amss, } @@ -352,6 +365,10 @@ func (h *handshake) synRcvdState(s *segment) *tcpip.Error { h.ep.updateRecentTimestamp(s.parsedOptions.TSVal, h.ackNum, s.sequenceNumber) } h.state = handshakeCompleted + h.ep.mu.Lock() + h.ep.transitionToStateEstablishedLocked(h) + h.ep.mu.Unlock() + return nil } @@ -484,7 +501,7 @@ func (h *handshake) execute() *tcpip.Error { WS: h.rcvWndScale, TS: true, TSVal: h.ep.timestamp(), - TSEcr: h.ep.recentTS, + TSEcr: h.ep.recentTimestamp(), SACKPermitted: bool(sackEnabled), MSS: h.ep.amss, } @@ -775,7 +792,7 @@ func (e *endpoint) makeOptions(sackBlocks []header.SACKBlock) []byte { // Ref: https://tools.ietf.org/html/rfc7323#section-5.4. offset += header.EncodeNOP(options[offset:]) offset += header.EncodeNOP(options[offset:]) - offset += header.EncodeTSOption(e.timestamp(), uint32(e.recentTS), options[offset:]) + offset += header.EncodeTSOption(e.timestamp(), e.recentTimestamp(), options[offset:]) } if e.sackPermitted && len(sackBlocks) > 0 { offset += header.EncodeNOP(options[offset:]) @@ -794,7 +811,7 @@ func (e *endpoint) makeOptions(sackBlocks []header.SACKBlock) []byte { // sendRaw sends a TCP segment to the endpoint's peer. func (e *endpoint) sendRaw(data buffer.VectorisedView, flags byte, seq, ack seqnum.Value, rcvWnd seqnum.Size) *tcpip.Error { var sackBlocks []header.SACKBlock - if e.state == StateEstablished && e.rcv.pendingBufSize > 0 && (flags&header.TCPFlagAck != 0) { + if e.EndpointState() == StateEstablished && e.rcv.pendingBufSize > 0 && (flags&header.TCPFlagAck != 0) { sackBlocks = e.sack.Blocks[:e.sack.NumBlocks] } options := e.makeOptions(sackBlocks) @@ -831,6 +848,9 @@ func (e *endpoint) handleWrite() *tcpip.Error { } func (e *endpoint) handleClose() *tcpip.Error { + if !e.EndpointState().connected() { + return nil + } // Drain the send queue. e.handleWrite() @@ -847,13 +867,9 @@ func (e *endpoint) handleClose() *tcpip.Error { func (e *endpoint) resetConnectionLocked(err *tcpip.Error) { // Only send a reset if the connection is being aborted for a reason // other than receiving a reset. - if e.state == StateEstablished || e.state == StateCloseWait { - e.stack.Stats().TCP.EstablishedResets.Increment() - e.stack.Stats().TCP.CurrentEstablished.Decrement() - } - e.state = StateError + e.setEndpointState(StateError) e.HardError = err - if err != tcpip.ErrConnectionReset { + if err != tcpip.ErrConnectionReset && err != tcpip.ErrTimeout { // The exact sequence number to be used for the RST is the same as the // one used by Linux. We need to handle the case of window being shrunk // which can cause sndNxt to be outside the acceptable window on the @@ -871,26 +887,55 @@ func (e *endpoint) resetConnectionLocked(err *tcpip.Error) { } // completeWorkerLocked is called by the worker goroutine when it's about to -// exit. It marks the worker as completed and performs cleanup work if requested -// by Close(). +// exit. func (e *endpoint) completeWorkerLocked() { + // Worker is terminating(either due to moving to + // CLOSED or ERROR state, ensure we release all + // registrations port reservations even if the socket + // itself is not yet closed by the application. e.workerRunning = false if e.workerCleanup { e.cleanupLocked() } } +// transitionToStateEstablisedLocked transitions a given endpoint +// to an established state using the handshake parameters provided. +// It also initializes sender/receiver if required. +func (e *endpoint) transitionToStateEstablishedLocked(h *handshake) { + if e.snd == nil { + // Transfer handshake state to TCP connection. We disable + // receive window scaling if the peer doesn't support it + // (indicated by a negative send window scale). + e.snd = newSender(e, h.iss, h.ackNum-1, h.sndWnd, h.mss, h.sndWndScale) + } + if e.rcv == nil { + rcvBufSize := seqnum.Size(e.receiveBufferSize()) + e.rcvListMu.Lock() + e.rcv = newReceiver(e, h.ackNum-1, h.rcvWnd, h.effectiveRcvWndScale(), rcvBufSize) + // Bootstrap the auto tuning algorithm. Starting at zero will + // result in a really large receive window after the first auto + // tuning adjustment. + e.rcvAutoParams.prevCopied = int(h.rcvWnd) + e.rcvListMu.Unlock() + } + e.setEndpointState(StateEstablished) +} + // transitionToStateCloseLocked ensures that the endpoint is // cleaned up from the transport demuxer, "before" moving to // StateClose. This will ensure that no packet will be // delivered to this endpoint from the demuxer when the endpoint // is transitioned to StateClose. func (e *endpoint) transitionToStateCloseLocked() { - if e.state == StateClose { + if e.EndpointState() == StateClose { return } + // Mark the endpoint as fully closed for reads/writes. e.cleanupLocked() - e.state = StateClose + e.setEndpointState(StateClose) + e.stack.Stats().TCP.CurrentConnected.Decrement() + e.stack.Stats().TCP.EstablishedClosed.Increment() } // tryDeliverSegmentFromClosedEndpoint attempts to deliver the parsed @@ -904,7 +949,9 @@ func (e *endpoint) tryDeliverSegmentFromClosedEndpoint(s *segment) { s.decRef() return } - ep.(*endpoint).enqueueSegment(s) + if ep.(*endpoint).enqueueSegment(s) { + ep.(*endpoint).newSegmentWaker.Assert() + } } func (e *endpoint) handleReset(s *segment) (ok bool, err *tcpip.Error) { @@ -913,9 +960,8 @@ func (e *endpoint) handleReset(s *segment) (ok bool, err *tcpip.Error) { // except SYN-SENT, all reset (RST) segments are // validated by checking their SEQ-fields." So // we only process it if it's acceptable. - s.decRef() e.mu.Lock() - switch e.state { + switch e.EndpointState() { // In case of a RST in CLOSE-WAIT linux moves // the socket to closed state with an error set // to indicate EPIPE. @@ -939,99 +985,53 @@ func (e *endpoint) handleReset(s *segment) (ok bool, err *tcpip.Error) { e.transitionToStateCloseLocked() e.HardError = tcpip.ErrAborted e.mu.Unlock() + e.notifyProtocolGoroutine(notifyTickleWorker) return false, nil default: e.mu.Unlock() + // RFC 793, page 37 states that "in all states + // except SYN-SENT, all reset (RST) segments are + // validated by checking their SEQ-fields." So + // we only process it if it's acceptable. + + // Notify protocol goroutine. This is required when + // handleSegment is invoked from the processor goroutine + // rather than the worker goroutine. + e.notifyProtocolGoroutine(notifyResetByPeer) return false, tcpip.ErrConnectionReset } } return true, nil } -// handleSegments pulls segments from the queue and processes them. It returns -// no error if the protocol loop should continue, an error otherwise. -func (e *endpoint) handleSegments() *tcpip.Error { +// handleSegments processes all inbound segments. +func (e *endpoint) handleSegments(fastPath bool) *tcpip.Error { checkRequeue := true for i := 0; i < maxSegmentsPerWake; i++ { - e.mu.RLock() - state := e.state - e.mu.RUnlock() - if state == StateClose { - // When we get into StateClose while processing from the queue, - // return immediately and let the protocolMainloop handle it. - // - // We can reach StateClose only while processing a previous segment - // or a notification from the protocolMainLoop (caller goroutine). - // This means that with this return, the segment dequeue below can - // never occur on a closed endpoint. + if e.EndpointState() == StateClose || e.EndpointState() == StateError { return nil } - s := e.segmentQueue.dequeue() if s == nil { checkRequeue = false break } - // Invoke the tcp probe if installed. - if e.probe != nil { - e.probe(e.completeState()) + cont, err := e.handleSegment(s) + if err != nil { + s.decRef() + return err } - - if s.flagIsSet(header.TCPFlagRst) { - if ok, err := e.handleReset(s); !ok { - return err - } - } else if s.flagIsSet(header.TCPFlagSyn) { - // See: https://tools.ietf.org/html/rfc5961#section-4.1 - // 1) If the SYN bit is set, irrespective of the sequence number, TCP - // MUST send an ACK (also referred to as challenge ACK) to the remote - // peer: - // - // <SEQ=SND.NXT><ACK=RCV.NXT><CTL=ACK> - // - // After sending the acknowledgment, TCP MUST drop the unacceptable - // segment and stop processing further. - // - // By sending an ACK, the remote peer is challenged to confirm the loss - // of the previous connection and the request to start a new connection. - // A legitimate peer, after restart, would not have a TCB in the - // synchronized state. Thus, when the ACK arrives, the peer should send - // a RST segment back with the sequence number derived from the ACK - // field that caused the RST. - - // This RST will confirm that the remote peer has indeed closed the - // previous connection. Upon receipt of a valid RST, the local TCP - // endpoint MUST terminate its connection. The local TCP endpoint - // should then rely on SYN retransmission from the remote end to - // re-establish the connection. - - e.snd.sendAck() - } else if s.flagIsSet(header.TCPFlagAck) { - // Patch the window size in the segment according to the - // send window scale. - s.window <<= e.snd.sndWndScale - - // RFC 793, page 41 states that "once in the ESTABLISHED - // state all segments must carry current acknowledgment - // information." - drop, err := e.rcv.handleRcvdSegment(s) - if err != nil { - s.decRef() - return err - } - if drop { - s.decRef() - continue - } - e.snd.handleRcvdSegment(s) + if !cont { + s.decRef() + return nil } - s.decRef() } - // If the queue is not empty, make sure we'll wake up in the next - // iteration. - if checkRequeue && !e.segmentQueue.empty() { + // When fastPath is true we don't want to wake up the worker + // goroutine. If the endpoint has more segments to process the + // dispatcher will call handleSegments again anyway. + if !fastPath && checkRequeue && !e.segmentQueue.empty() { e.newSegmentWaker.Assert() } @@ -1040,23 +1040,113 @@ func (e *endpoint) handleSegments() *tcpip.Error { e.snd.sendAck() } - e.resetKeepaliveTimer(true) + e.resetKeepaliveTimer(true /* receivedData */) return nil } +// handleSegment handles a given segment and notifies the worker goroutine if +// if the connection should be terminated. +func (e *endpoint) handleSegment(s *segment) (cont bool, err *tcpip.Error) { + // Invoke the tcp probe if installed. + if e.probe != nil { + e.probe(e.completeState()) + } + + if s.flagIsSet(header.TCPFlagRst) { + if ok, err := e.handleReset(s); !ok { + return false, err + } + } else if s.flagIsSet(header.TCPFlagSyn) { + // See: https://tools.ietf.org/html/rfc5961#section-4.1 + // 1) If the SYN bit is set, irrespective of the sequence number, TCP + // MUST send an ACK (also referred to as challenge ACK) to the remote + // peer: + // + // <SEQ=SND.NXT><ACK=RCV.NXT><CTL=ACK> + // + // After sending the acknowledgment, TCP MUST drop the unacceptable + // segment and stop processing further. + // + // By sending an ACK, the remote peer is challenged to confirm the loss + // of the previous connection and the request to start a new connection. + // A legitimate peer, after restart, would not have a TCB in the + // synchronized state. Thus, when the ACK arrives, the peer should send + // a RST segment back with the sequence number derived from the ACK + // field that caused the RST. + + // This RST will confirm that the remote peer has indeed closed the + // previous connection. Upon receipt of a valid RST, the local TCP + // endpoint MUST terminate its connection. The local TCP endpoint + // should then rely on SYN retransmission from the remote end to + // re-establish the connection. + + e.snd.sendAck() + } else if s.flagIsSet(header.TCPFlagAck) { + // Patch the window size in the segment according to the + // send window scale. + s.window <<= e.snd.sndWndScale + + // RFC 793, page 41 states that "once in the ESTABLISHED + // state all segments must carry current acknowledgment + // information." + drop, err := e.rcv.handleRcvdSegment(s) + if err != nil { + return false, err + } + if drop { + return true, nil + } + + // Now check if the received segment has caused us to transition + // to a CLOSED state, if yes then terminate processing and do + // not invoke the sender. + e.mu.RLock() + state := e.state + e.mu.RUnlock() + if state == StateClose { + // When we get into StateClose while processing from the queue, + // return immediately and let the protocolMainloop handle it. + // + // We can reach StateClose only while processing a previous segment + // or a notification from the protocolMainLoop (caller goroutine). + // This means that with this return, the segment dequeue below can + // never occur on a closed endpoint. + s.decRef() + return false, nil + } + + e.snd.handleRcvdSegment(s) + } + + return true, nil +} + // keepaliveTimerExpired is called when the keepaliveTimer fires. We send TCP // keepalive packets periodically when the connection is idle. If we don't hear // from the other side after a number of tries, we terminate the connection. func (e *endpoint) keepaliveTimerExpired() *tcpip.Error { + e.mu.RLock() + userTimeout := e.userTimeout + e.mu.RUnlock() + e.keepalive.Lock() if !e.keepalive.enabled || !e.keepalive.timer.checkExpiration() { e.keepalive.Unlock() return nil } + // If a userTimeout is set then abort the connection if it is + // exceeded. + if userTimeout != 0 && time.Since(e.rcv.lastRcvdAckTime) >= userTimeout && e.keepalive.unacked > 0 { + e.keepalive.Unlock() + e.stack.Stats().TCP.EstablishedTimedout.Increment() + return tcpip.ErrTimeout + } + if e.keepalive.unacked >= e.keepalive.count { e.keepalive.Unlock() + e.stack.Stats().TCP.EstablishedTimedout.Increment() return tcpip.ErrTimeout } @@ -1073,7 +1163,6 @@ func (e *endpoint) keepaliveTimerExpired() *tcpip.Error { // whether it is enabled for this endpoint. func (e *endpoint) resetKeepaliveTimer(receivedData bool) { e.keepalive.Lock() - defer e.keepalive.Unlock() if receivedData { e.keepalive.unacked = 0 } @@ -1081,6 +1170,7 @@ func (e *endpoint) resetKeepaliveTimer(receivedData bool) { // data to send. if !e.keepalive.enabled || e.snd == nil || e.snd.sndUna != e.snd.sndNxt { e.keepalive.timer.disable() + e.keepalive.Unlock() return } if e.keepalive.unacked > 0 { @@ -1088,6 +1178,7 @@ func (e *endpoint) resetKeepaliveTimer(receivedData bool) { } else { e.keepalive.timer.enable(e.keepalive.idle) } + e.keepalive.Unlock() } // disableKeepaliveTimer stops the keepalive timer. @@ -1100,7 +1191,7 @@ func (e *endpoint) disableKeepaliveTimer() { // protocolMainLoop is the main loop of the TCP protocol. It runs in its own // goroutine and is responsible for sending segments and handling received // segments. -func (e *endpoint) protocolMainLoop(handshake bool) *tcpip.Error { +func (e *endpoint) protocolMainLoop(handshake bool, wakerInitDone chan<- struct{}) *tcpip.Error { var closeTimer *time.Timer var closeWaker sleep.Waker @@ -1122,6 +1213,7 @@ func (e *endpoint) protocolMainLoop(handshake bool) *tcpip.Error { } e.mu.Unlock() + e.workMu.Unlock() // When the protocol loop exits we should wake up our waiters. e.waiterQueue.Notify(waiter.EventHUp | waiter.EventErr | waiter.EventIn | waiter.EventOut) } @@ -1133,7 +1225,7 @@ func (e *endpoint) protocolMainLoop(handshake bool) *tcpip.Error { initialRcvWnd := e.initialReceiveWindow() h := newHandshake(e, seqnum.Size(initialRcvWnd)) e.mu.Lock() - h.ep.state = StateSynSent + h.ep.setEndpointState(StateSynSent) e.mu.Unlock() if err := h.execute(); err != nil { @@ -1142,41 +1234,18 @@ func (e *endpoint) protocolMainLoop(handshake bool) *tcpip.Error { e.lastErrorMu.Unlock() e.mu.Lock() - e.stack.Stats().TCP.EstablishedResets.Increment() - e.stack.Stats().TCP.CurrentEstablished.Decrement() - e.state = StateError + e.setEndpointState(StateError) e.HardError = err // Lock released below. epilogue() - return err } - - // Transfer handshake state to TCP connection. We disable - // receive window scaling if the peer doesn't support it - // (indicated by a negative send window scale). - e.snd = newSender(e, h.iss, h.ackNum-1, h.sndWnd, h.mss, h.sndWndScale) - - rcvBufSize := seqnum.Size(e.receiveBufferSize()) - e.rcvListMu.Lock() - e.rcv = newReceiver(e, h.ackNum-1, h.rcvWnd, h.effectiveRcvWndScale(), rcvBufSize) - // boot strap the auto tuning algorithm. Starting at zero will - // result in a large step function on the first proper causing - // the window to just go to a really large value after the first - // RTT itself. - e.rcvAutoParams.prevCopied = initialRcvWnd - e.rcvListMu.Unlock() - e.stack.Stats().TCP.CurrentEstablished.Increment() - e.mu.Lock() - e.state = StateEstablished - e.mu.Unlock() } e.keepalive.timer.init(&e.keepalive.waker) defer e.keepalive.timer.cleanup() - // Tell waiters that the endpoint is connected and writable. e.mu.Lock() drained := e.drainDone != nil e.mu.Unlock() @@ -1185,8 +1254,6 @@ func (e *endpoint) protocolMainLoop(handshake bool) *tcpip.Error { <-e.undrain } - e.waiterQueue.Notify(waiter.EventOut) - // Set up the functions that will be called when the main protocol loop // wakes up. funcs := []struct { @@ -1202,17 +1269,14 @@ func (e *endpoint) protocolMainLoop(handshake bool) *tcpip.Error { f: e.handleClose, }, { - w: &e.newSegmentWaker, - f: e.handleSegments, - }, - { w: &closeWaker, f: func() *tcpip.Error { // This means the socket is being closed due - // to the TCP_FIN_WAIT2 timeout was hit. Just + // to the TCP-FIN-WAIT2 timeout was hit. Just // mark the socket as closed. e.mu.Lock() e.transitionToStateCloseLocked() + e.workerCleanup = true e.mu.Unlock() return nil }, @@ -1221,12 +1285,19 @@ func (e *endpoint) protocolMainLoop(handshake bool) *tcpip.Error { w: &e.snd.resendWaker, f: func() *tcpip.Error { if !e.snd.retransmitTimerExpired() { + e.stack.Stats().TCP.EstablishedTimedout.Increment() return tcpip.ErrTimeout } return nil }, }, { + w: &e.newSegmentWaker, + f: func() *tcpip.Error { + return e.handleSegments(false /* fastPath */) + }, + }, + { w: &e.keepalive.waker, f: e.keepaliveTimerExpired, }, @@ -1253,14 +1324,16 @@ func (e *endpoint) protocolMainLoop(handshake bool) *tcpip.Error { } if n¬ifyReset != 0 { - e.mu.Lock() - e.resetConnectionLocked(tcpip.ErrConnectionAborted) - e.mu.Unlock() + return tcpip.ErrConnectionAborted + } + + if n¬ifyResetByPeer != 0 { + return tcpip.ErrConnectionReset } if n¬ifyClose != 0 && closeTimer == nil { e.mu.Lock() - if e.state == StateFinWait2 && e.closed { + if e.EndpointState() == StateFinWait2 && e.closed { // The socket has been closed and we are in FIN_WAIT2 // so start the FIN_WAIT2 timer. closeTimer = time.AfterFunc(e.tcpLingerTimeout, func() { @@ -1280,11 +1353,11 @@ func (e *endpoint) protocolMainLoop(handshake bool) *tcpip.Error { if n¬ifyDrain != 0 { for !e.segmentQueue.empty() { - if err := e.handleSegments(); err != nil { + if err := e.handleSegments(false /* fastPath */); err != nil { return err } } - if e.state != StateClose && e.state != StateError { + if e.EndpointState() != StateClose && e.EndpointState() != StateError { // Only block the worker if the endpoint // is not in closed state or error state. close(e.drainDone) @@ -1309,14 +1382,21 @@ func (e *endpoint) protocolMainLoop(handshake bool) *tcpip.Error { s.AddWaker(funcs[i].w, i) } + // Notify the caller that the waker initialization is complete and the + // endpoint is ready. + if wakerInitDone != nil { + close(wakerInitDone) + } + + // Tell waiters that the endpoint is connected and writable. + e.waiterQueue.Notify(waiter.EventOut) + // The following assertions and notifications are needed for restored // endpoints. Fresh newly created endpoints have empty states and should // not invoke any. - e.segmentQueue.mu.Lock() - if !e.segmentQueue.list.Empty() { + if !e.segmentQueue.empty() { e.newSegmentWaker.Assert() } - e.segmentQueue.mu.Unlock() e.rcvListMu.Lock() if !e.rcvList.Empty() { @@ -1331,28 +1411,53 @@ func (e *endpoint) protocolMainLoop(handshake bool) *tcpip.Error { // Main loop. Handle segments until both send and receive ends of the // connection have completed. + cleanupOnError := func(err *tcpip.Error) { + e.mu.Lock() + e.workerCleanup = true + if err != nil { + e.resetConnectionLocked(err) + } + // Lock released below. + epilogue() + } - for e.state != StateTimeWait && e.state != StateClose && e.state != StateError { +loop: + for e.EndpointState() != StateTimeWait && e.EndpointState() != StateClose && e.EndpointState() != StateError { e.mu.Unlock() e.workMu.Unlock() v, _ := s.Fetch(true) e.workMu.Lock() - if err := funcs[v].f(); err != nil { - e.mu.Lock() - // Ensure we release all endpoint registration and route - // references as the connection is now in an error - // state. - e.workerCleanup = true - e.resetConnectionLocked(err) - // Lock released below. - epilogue() + // We need to double check here because the notification maybe + // stale by the time we got around to processing it. + // + // NOTE: since we now hold the workMu the processors cannot + // change the state of the endpoint so it's safe to proceed + // after this check. + switch e.EndpointState() { + case StateError: + // If the endpoint has already transitioned to an ERROR + // state just pass nil here as any reset that may need + // to be sent etc should already have been done and we + // just want to terminate the loop and cleanup the + // endpoint. + cleanupOnError(nil) return nil + case StateTimeWait: + fallthrough + case StateClose: + e.mu.Lock() + break loop + default: + if err := funcs[v].f(); err != nil { + cleanupOnError(err) + return nil + } + e.mu.Lock() } - e.mu.Lock() } - state := e.state + state := e.EndpointState() e.mu.Unlock() var reuseTW func() if state == StateTimeWait { @@ -1365,14 +1470,15 @@ func (e *endpoint) protocolMainLoop(handshake bool) *tcpip.Error { s.Done() // Wake up any waiters before we enter TIME_WAIT. e.waiterQueue.Notify(waiter.EventHUp | waiter.EventErr | waiter.EventIn | waiter.EventOut) + e.mu.Lock() + e.workerCleanup = true + e.mu.Unlock() reuseTW = e.doTimeWait() } // Mark endpoint as closed. e.mu.Lock() - if e.state != StateError { - e.stack.Stats().TCP.EstablishedResets.Increment() - e.stack.Stats().TCP.CurrentEstablished.Decrement() + if e.EndpointState() != StateError { e.transitionToStateCloseLocked() } @@ -1388,6 +1494,7 @@ func (e *endpoint) protocolMainLoop(handshake bool) *tcpip.Error { if s == nil { break } + e.tryDeliverSegmentFromClosedEndpoint(s) } @@ -1428,7 +1535,11 @@ func (e *endpoint) handleTimeWaitSegments() (extendTimeWait bool, reuseTW func() tcpEP := listenEP.(*endpoint) if EndpointState(tcpEP.State()) == StateListen { reuseTW = func() { - tcpEP.enqueueSegment(s) + if !tcpEP.enqueueSegment(s) { + s.decRef() + return + } + tcpEP.newSegmentWaker.Assert() } // We explicitly do not decRef // the segment as it's still |