diff options
Diffstat (limited to 'pkg/tcpip/transport/tcp/connect.go')
| -rw-r--r-- | pkg/tcpip/transport/tcp/connect.go | 58 |
1 files changed, 58 insertions, 0 deletions
diff --git a/pkg/tcpip/transport/tcp/connect.go b/pkg/tcpip/transport/tcp/connect.go index 14282d399..558dbc50a 100644 --- a/pkg/tcpip/transport/tcp/connect.go +++ b/pkg/tcpip/transport/tcp/connect.go @@ -827,9 +827,56 @@ func (e *endpoint) handleSegments() *tcpip.Error { e.snd.sendAck() } + e.resetKeepaliveTimer(true) + + return 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.keepalive.Lock() + if !e.keepalive.enabled || !e.keepalive.timer.checkExpiration() { + e.keepalive.Unlock() + return nil + } + + if e.keepalive.unacked >= e.keepalive.count { + e.keepalive.Unlock() + return tcpip.ErrConnectionReset + } + + // RFC1122 4.2.3.6: TCP keepalive is a dataless ACK with + // seg.seq = snd.nxt-1. + e.keepalive.unacked++ + e.keepalive.Unlock() + e.snd.sendSegment(nil, flagAck, e.snd.sndNxt-1) + e.resetKeepaliveTimer(false) return nil } +// resetKeepaliveTimer restarts or stops the keepalive timer, depending on +// 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 + } + // Start the keepalive timer IFF it's enabled and there is no pending + // data to send. + if !e.keepalive.enabled || e.snd == nil || e.snd.sndUna != e.snd.sndNxt { + e.keepalive.timer.disable() + return + } + if e.keepalive.unacked > 0 { + e.keepalive.timer.enable(e.keepalive.interval) + } else { + e.keepalive.timer.enable(e.keepalive.idle) + } +} + // 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. @@ -892,6 +939,9 @@ func (e *endpoint) protocolMainLoop(handshake bool) *tcpip.Error { e.rcvListMu.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() e.state = stateConnected @@ -938,6 +988,10 @@ func (e *endpoint) protocolMainLoop(handshake bool) *tcpip.Error { }, }, { + w: &e.keepalive.waker, + f: e.keepaliveTimerExpired, + }, + { w: &e.notificationWaker, f: func() *tcpip.Error { n := e.fetchNotifications() @@ -982,6 +1036,10 @@ func (e *endpoint) protocolMainLoop(handshake bool) *tcpip.Error { <-e.undrain } + if n¬ifyKeepaliveChanged != 0 { + e.resetKeepaliveTimer(true) + } + return nil }, }, |