diff options
Diffstat (limited to 'pkg/tcpip/transport/tcp/snd.go')
| -rw-r--r-- | pkg/tcpip/transport/tcp/snd.go | 46 |
1 files changed, 37 insertions, 9 deletions
diff --git a/pkg/tcpip/transport/tcp/snd.go b/pkg/tcpip/transport/tcp/snd.go index 376e81846..568bd7024 100644 --- a/pkg/tcpip/transport/tcp/snd.go +++ b/pkg/tcpip/transport/tcp/snd.go @@ -51,6 +51,11 @@ type congestionControl interface { // number of packet's that were acked by the most recent cumulative // acknowledgement. Update(packetsAcked int) + + // PostRecovery is invoked when the sender is exiting a fast retransmit/ + // recovery phase. This provides congestion control algorithms a way + // to adjust their state when exiting recovery. + PostRecovery() } // sender holds the state necessary to send TCP segments. @@ -174,7 +179,7 @@ func newSender(ep *endpoint, iss, irs seqnum.Value, sndWnd seqnum.Size, mss uint }, } - s.cc = newRenoCC(s) + s.cc = s.initCongestionControl(ep.cc) // A negative sndWndScale means that no scaling is in use, otherwise we // store the scaling value. @@ -189,6 +194,17 @@ func newSender(ep *endpoint, iss, irs seqnum.Value, sndWnd seqnum.Size, mss uint return s } +func (s *sender) initCongestionControl(congestionControlName CongestionControlOption) congestionControl { + switch congestionControlName { + case ccCubic: + return newCubicCC(s) + case ccReno: + fallthrough + default: + return newRenoCC(s) + } +} + // updateMaxPayloadSize updates the maximum payload size based on the given // MTU. If this is in response to "packet too big" control packets (indicated // by the count argument), it also reduces the number of outstanding packets and @@ -409,6 +425,7 @@ func (s *sender) sendData() { } func (s *sender) enterFastRecovery() { + s.fr.active = true // Save state to reflect we're now in fast recovery. // See : https://tools.ietf.org/html/rfc5681#section-3.2 Step 3. // We inflat the cwnd by 3 to account for the 3 packets which triggered @@ -417,7 +434,6 @@ func (s *sender) enterFastRecovery() { s.fr.first = s.sndUna s.fr.last = s.sndNxt - 1 s.fr.maxCwnd = s.sndCwnd + s.outstanding - s.fr.active = true } func (s *sender) leaveFastRecovery() { @@ -429,12 +445,13 @@ func (s *sender) leaveFastRecovery() { // Deflate cwnd. It had been artificially inflated when new dups arrived. s.sndCwnd = s.sndSsthresh + s.cc.PostRecovery() } // checkDuplicateAck is called when an ack is received. It manages the state // related to duplicate acks and determines if a retransmit is needed according // to the rules in RFC 6582 (NewReno). -func (s *sender) checkDuplicateAck(seg *segment) bool { +func (s *sender) checkDuplicateAck(seg *segment) (rtx bool) { ack := seg.ackNumber if s.fr.active { // We are in fast recovery mode. Ignore the ack if it's out of @@ -474,6 +491,7 @@ func (s *sender) checkDuplicateAck(seg *segment) bool { // // N.B. The retransmit timer will be reset by the caller. s.fr.first = ack + s.dupAckCount = 0 return true } @@ -508,16 +526,11 @@ func (s *sender) checkDuplicateAck(seg *segment) bool { return true } -// updateCwnd updates the congestion window based on the number of packets that -// were acknowledged. -func (s *sender) updateCwnd(packetsAcked int) { -} - // handleRcvdSegment is called when a segment is received; it is responsible for // updating the send-related state. func (s *sender) handleRcvdSegment(seg *segment) { // Check if we can extract an RTT measurement from this ack. - if s.rttMeasureSeqNum.LessThan(seg.ackNumber) { + if !s.ep.sendTSOk && s.rttMeasureSeqNum.LessThan(seg.ackNumber) { s.updateRTO(time.Now().Sub(s.rttMeasureTime)) s.rttMeasureSeqNum = s.sndNxt } @@ -534,10 +547,25 @@ func (s *sender) handleRcvdSegment(seg *segment) { // Ignore ack if it doesn't acknowledge any new data. ack := seg.ackNumber if (ack - 1).InRange(s.sndUna, s.sndNxt) { + s.dupAckCount = 0 // When an ack is received we must reset the timer. We stop it // here and it will be restarted later if needed. s.resendTimer.disable() + // See : https://tools.ietf.org/html/rfc1323#section-3.3. + // Specifically we should only update the RTO using TSEcr if the + // following condition holds: + // + // A TSecr value received in a segment is used to update the + // averaged RTT measurement only if the segment acknowledges + // some new data, i.e., only if it advances the left edge of + // the send window. + if s.ep.sendTSOk && seg.parsedOptions.TSEcr != 0 { + // TSVal/Ecr values sent by Netstack are at a millisecond + // granularity. + elapsed := time.Duration(s.ep.timestamp()-seg.parsedOptions.TSEcr) * time.Millisecond + s.updateRTO(elapsed) + } // Remove all acknowledged data from the write list. acked := s.sndUna.Size(ack) s.sndUna = ack |