diff options
Diffstat (limited to 'pkg/tcpip/transport/tcp/rcv.go')
| -rw-r--r-- | pkg/tcpip/transport/tcp/rcv.go | 27 |
1 files changed, 17 insertions, 10 deletions
diff --git a/pkg/tcpip/transport/tcp/rcv.go b/pkg/tcpip/transport/tcp/rcv.go index e90f9a7d9..a8f490c4a 100644 --- a/pkg/tcpip/transport/tcp/rcv.go +++ b/pkg/tcpip/transport/tcp/rcv.go @@ -220,25 +220,24 @@ func (r *receiver) consumeSegment(s *segment, segSeq seqnum.Value, segLen seqnum return true } -// updateRTT updates the receiver RTT measurement based on the sequence number -// of the received segment. -func (r *receiver) updateRTT() { +// updateRTTLocked updates the receiver RTT measurement based on the sequence +// number of the received segment. +// +// Precondition: Caller must hold r.ep.rcvListMu. +func (r *receiver) updateRTTLocked() { // From: https://public.lanl.gov/radiant/pubs/drs/sc2001-poster.pdf // // A system that is only transmitting acknowledgements can still // estimate the round-trip time by observing the time between when a byte // is first acknowledged and the receipt of data that is at least one // window beyond the sequence number that was acknowledged. - r.ep.rcvListMu.Lock() if r.ep.rcvAutoParams.rttMeasureTime.IsZero() { // New measurement. r.ep.rcvAutoParams.rttMeasureTime = time.Now() r.ep.rcvAutoParams.rttMeasureSeqNumber = r.rcvNxt.Add(r.rcvWnd) - r.ep.rcvListMu.Unlock() return } if r.rcvNxt.LessThan(r.ep.rcvAutoParams.rttMeasureSeqNumber) { - r.ep.rcvListMu.Unlock() return } rtt := time.Since(r.ep.rcvAutoParams.rttMeasureTime) @@ -250,7 +249,6 @@ func (r *receiver) updateRTT() { } r.ep.rcvAutoParams.rttMeasureTime = time.Now() r.ep.rcvAutoParams.rttMeasureSeqNumber = r.rcvNxt.Add(r.rcvWnd) - r.ep.rcvListMu.Unlock() } // handleRcvdSegment handles TCP segments directed at the connection managed by @@ -291,11 +289,20 @@ func (r *receiver) handleRcvdSegment(s *segment) { return } - // Since we consumed a segment update the receiver's RTT estimate - // if required. + r.ep.rcvListMu.Lock() + // FIXME(b/137581805): Using the runtime clock here is incorrect as it + // doesn't account for potentially virtualized time. + now := time.Now().UnixNano() + if s.flagIsSet(header.TCPFlagAck) { + r.ep.rcvLastAckNanos = now + } if segLen > 0 { - r.updateRTT() + // Since we consumed a segment update the receiver's RTT estimate if + // required. + r.ep.rcvLastDataNanos = now + r.updateRTTLocked() } + r.ep.rcvListMu.Unlock() // By consuming the current segment, we may have filled a gap in the // sequence number domain that allows pending segments to be consumed |