diff options
Diffstat (limited to 'pkg/tcpip/transport/tcp/snd.go')
| -rw-r--r-- | pkg/tcpip/transport/tcp/snd.go | 440 |
1 files changed, 176 insertions, 264 deletions
diff --git a/pkg/tcpip/transport/tcp/snd.go b/pkg/tcpip/transport/tcp/snd.go index faca35892..cf2e8dcd8 100644 --- a/pkg/tcpip/transport/tcp/snd.go +++ b/pkg/tcpip/transport/tcp/snd.go @@ -26,6 +26,7 @@ import ( "gvisor.dev/gvisor/pkg/tcpip/buffer" "gvisor.dev/gvisor/pkg/tcpip/header" "gvisor.dev/gvisor/pkg/tcpip/seqnum" + "gvisor.dev/gvisor/pkg/tcpip/stack" ) const ( @@ -85,56 +86,12 @@ type lossRecovery interface { // // +stateify savable type sender struct { + stack.TCPSenderState ep *endpoint - // lastSendTime is the timestamp when the last packet was sent. - lastSendTime time.Time `state:".(unixTime)"` - - // dupAckCount is the number of duplicated acks received. It is used for - // fast retransmit. - dupAckCount int - - // fr holds state related to fast recovery. - fr fastRecovery - // lr is the loss recovery algorithm used by the sender. lr lossRecovery - // sndCwnd is the congestion window, in packets. - sndCwnd int - - // sndSsthresh is the threshold between slow start and congestion - // avoidance. - sndSsthresh int - - // sndCAAckCount is the number of packets acknowledged during congestion - // avoidance. When enough packets have been ack'd (typically cwnd - // packets), the congestion window is incremented by one. - sndCAAckCount int - - // outstanding is the number of outstanding packets, that is, packets - // that have been sent but not yet acknowledged. - outstanding int - - // sackedOut is the number of packets which are selectively acked. - sackedOut int - - // sndWnd is the send window size. - sndWnd seqnum.Size - - // sndUna is the next unacknowledged sequence number. - sndUna seqnum.Value - - // sndNxt is the sequence number of the next segment to be sent. - sndNxt seqnum.Value - - // rttMeasureSeqNum is the sequence number being used for the latest RTT - // measurement. - rttMeasureSeqNum seqnum.Value - - // rttMeasureTime is the time when the rttMeasureSeqNum was sent. - rttMeasureTime time.Time `state:".(unixTime)"` - // firstRetransmittedSegXmitTime is the original transmit time of // the first segment that was retransmitted due to RTO expiration. firstRetransmittedSegXmitTime time.Time `state:".(unixTime)"` @@ -147,17 +104,15 @@ type sender struct { // window probes. unackZeroWindowProbes uint32 `state:"nosave"` - closed bool writeNext *segment writeList segmentList resendTimer timer `state:"nosave"` resendWaker sleep.Waker `state:"nosave"` - // rtt.srtt, rtt.rttvar, and rto are the "smoothed round-trip time", - // "round-trip time variation" and "retransmit timeout", as defined in + // rtt.TCPRTTState.SRTT and rtt.TCPRTTState.RTTVar are the "smoothed + // round-trip time", and "round-trip time variation", as defined in // section 2 of RFC 6298. rtt rtt - rto time.Duration // minRTO is the minimum permitted value for sender.rto. minRTO time.Duration @@ -168,20 +123,9 @@ type sender struct { // maxRetries is the maximum permitted retransmissions. maxRetries uint32 - // maxPayloadSize is the maximum size of the payload of a given segment. - // It is initialized on demand. - maxPayloadSize int - // gso is set if generic segmentation offload is enabled. gso bool - // sndWndScale is the number of bits to shift left when reading the send - // window size from a segment. - sndWndScale uint8 - - // maxSentAck is the maxium acknowledgement actually sent. - maxSentAck seqnum.Value - // state is the current state of congestion control for this endpoint. state tcpip.CongestionControlState @@ -209,41 +153,7 @@ type sender struct { type rtt struct { sync.Mutex `state:"nosave"` - srtt time.Duration - rttvar time.Duration - srttInited bool -} - -// fastRecovery holds information related to fast recovery from a packet loss. -// -// +stateify savable -type fastRecovery struct { - // active whether the endpoint is in fast recovery. The following fields - // are only meaningful when active is true. - active bool - - // first and last represent the inclusive sequence number range being - // recovered. - first seqnum.Value - last seqnum.Value - - // maxCwnd is the maximum value the congestion window may be inflated to - // due to duplicate acks. This exists to avoid attacks where the - // receiver intentionally sends duplicate acks to artificially inflate - // the sender's cwnd. - maxCwnd int - - // highRxt is the highest sequence number which has been retransmitted - // during the current loss recovery phase. - // See: RFC 6675 Section 2 for details. - highRxt seqnum.Value - - // rescueRxt is the highest sequence number which has been - // optimistically retransmitted to prevent stalling of the ACK clock - // when there is loss at the end of the window and no new data is - // available for transmission. - // See: RFC 6675 Section 2 for details. - rescueRxt seqnum.Value + stack.TCPRTTState } func newSender(ep *endpoint, iss, irs seqnum.Value, sndWnd seqnum.Size, mss uint16, sndWndScale int) *sender { @@ -253,20 +163,22 @@ func newSender(ep *endpoint, iss, irs seqnum.Value, sndWnd seqnum.Size, mss uint maxPayloadSize := int(mss) - ep.maxOptionSize() s := &sender{ - ep: ep, - sndWnd: sndWnd, - sndUna: iss + 1, - sndNxt: iss + 1, - rto: 1 * time.Second, - rttMeasureSeqNum: iss + 1, - lastSendTime: time.Now(), - maxPayloadSize: maxPayloadSize, - maxSentAck: irs + 1, - fr: fastRecovery{ - // See: https://tools.ietf.org/html/rfc6582#section-3.2 Step 1. - last: iss, - highRxt: iss, - rescueRxt: iss, + ep: ep, + TCPSenderState: stack.TCPSenderState{ + SndWnd: sndWnd, + SndUna: iss + 1, + SndNxt: iss + 1, + RTTMeasureSeqNum: iss + 1, + LastSendTime: time.Now(), + MaxPayloadSize: maxPayloadSize, + MaxSentAck: irs + 1, + FastRecovery: stack.TCPFastRecoveryState{ + // See: https://tools.ietf.org/html/rfc6582#section-3.2 Step 1. + Last: iss, + HighRxt: iss, + RescueRxt: iss, + }, + RTO: 1 * time.Second, }, gso: ep.gso != nil, } @@ -282,7 +194,7 @@ func newSender(ep *endpoint, iss, irs seqnum.Value, sndWnd seqnum.Size, mss uint // A negative sndWndScale means that no scaling is in use, otherwise we // store the scaling value. if sndWndScale > 0 { - s.sndWndScale = uint8(sndWndScale) + s.SndWndScale = uint8(sndWndScale) } s.resendTimer.init(&s.resendWaker) @@ -294,7 +206,7 @@ func newSender(ep *endpoint, iss, irs seqnum.Value, sndWnd seqnum.Size, mss uint // Initialize SACK Scoreboard after updating max payload size as we use // the maxPayloadSize as the smss when determining if a segment is lost // etc. - s.ep.scoreboard = NewSACKScoreboard(uint16(s.maxPayloadSize), iss) + s.ep.scoreboard = NewSACKScoreboard(uint16(s.MaxPayloadSize), iss) // Get Stack wide config. var minRTO tcpip.TCPMinRTOOption @@ -322,10 +234,10 @@ func newSender(ep *endpoint, iss, irs seqnum.Value, sndWnd seqnum.Size, mss uint // returns a handle to it. It also initializes the sndCwnd and sndSsThresh to // their initial values. func (s *sender) initCongestionControl(congestionControlName tcpip.CongestionControlOption) congestionControl { - s.sndCwnd = InitialCwnd + s.SndCwnd = InitialCwnd // Set sndSsthresh to the maximum int value, which depends on the // platform. - s.sndSsthresh = int(^uint(0) >> 1) + s.Ssthresh = int(^uint(0) >> 1) switch congestionControlName { case ccCubic: @@ -339,7 +251,7 @@ func (s *sender) initCongestionControl(congestionControlName tcpip.CongestionCon // initLossRecovery initiates the loss recovery algorithm for the sender. func (s *sender) initLossRecovery() lossRecovery { - if s.ep.sackPermitted { + if s.ep.SACKPermitted { return newSACKRecovery(s) } return newRenoRecovery(s) @@ -355,7 +267,7 @@ func (s *sender) updateMaxPayloadSize(mtu, count int) { m -= s.ep.maxOptionSize() // We don't adjust up for now. - if m >= s.maxPayloadSize { + if m >= s.MaxPayloadSize { return } @@ -364,8 +276,8 @@ func (s *sender) updateMaxPayloadSize(mtu, count int) { m = 1 } - oldMSS := s.maxPayloadSize - s.maxPayloadSize = m + oldMSS := s.MaxPayloadSize + s.MaxPayloadSize = m if s.gso { s.ep.gso.MSS = uint16(m) } @@ -380,9 +292,9 @@ func (s *sender) updateMaxPayloadSize(mtu, count int) { // maxPayloadSize. s.ep.scoreboard.smss = uint16(m) - s.outstanding -= count - if s.outstanding < 0 { - s.outstanding = 0 + s.Outstanding -= count + if s.Outstanding < 0 { + s.Outstanding = 0 } // Rewind writeNext to the first segment exceeding the MTU. Do nothing @@ -401,10 +313,10 @@ func (s *sender) updateMaxPayloadSize(mtu, count int) { nextSeg = seg } - if s.ep.sackPermitted && s.ep.scoreboard.IsSACKED(seg.sackBlock()) { + if s.ep.SACKPermitted && s.ep.scoreboard.IsSACKED(seg.sackBlock()) { // Update sackedOut for new maximum payload size. - s.sackedOut -= s.pCount(seg, oldMSS) - s.sackedOut += s.pCount(seg, s.maxPayloadSize) + s.SackedOut -= s.pCount(seg, oldMSS) + s.SackedOut += s.pCount(seg, s.MaxPayloadSize) } } @@ -416,32 +328,32 @@ func (s *sender) updateMaxPayloadSize(mtu, count int) { // sendAck sends an ACK segment. func (s *sender) sendAck() { - s.sendSegmentFromView(buffer.VectorisedView{}, header.TCPFlagAck, s.sndNxt) + s.sendSegmentFromView(buffer.VectorisedView{}, header.TCPFlagAck, s.SndNxt) } // updateRTO updates the retransmit timeout when a new roud-trip time is // available. This is done in accordance with section 2 of RFC 6298. func (s *sender) updateRTO(rtt time.Duration) { s.rtt.Lock() - if !s.rtt.srttInited { - s.rtt.rttvar = rtt / 2 - s.rtt.srtt = rtt - s.rtt.srttInited = true + if !s.rtt.TCPRTTState.SRTTInited { + s.rtt.TCPRTTState.RTTVar = rtt / 2 + s.rtt.TCPRTTState.SRTT = rtt + s.rtt.TCPRTTState.SRTTInited = true } else { - diff := s.rtt.srtt - rtt + diff := s.rtt.TCPRTTState.SRTT - rtt if diff < 0 { diff = -diff } - // Use RFC6298 standard algorithm to update rttvar and srtt when + // Use RFC6298 standard algorithm to update TCPRTTState.RTTVar and TCPRTTState.SRTT when // no timestamps are available. - if !s.ep.sendTSOk { - s.rtt.rttvar = (3*s.rtt.rttvar + diff) / 4 - s.rtt.srtt = (7*s.rtt.srtt + rtt) / 8 + if !s.ep.SendTSOk { + s.rtt.TCPRTTState.RTTVar = (3*s.rtt.TCPRTTState.RTTVar + diff) / 4 + s.rtt.TCPRTTState.SRTT = (7*s.rtt.TCPRTTState.SRTT + rtt) / 8 } else { // When we are taking RTT measurements of every ACK then // we need to use a modified method as specified in // https://tools.ietf.org/html/rfc7323#appendix-G - if s.outstanding == 0 { + if s.Outstanding == 0 { s.rtt.Unlock() return } @@ -449,7 +361,7 @@ func (s *sender) updateRTO(rtt time.Duration) { // terms of packets and not bytes. This is similar to // how linux also does cwnd and inflight. In practice // this approximation works as expected. - expectedSamples := math.Ceil(float64(s.outstanding) / 2) + expectedSamples := math.Ceil(float64(s.Outstanding) / 2) // alpha & beta values are the original values as recommended in // https://tools.ietf.org/html/rfc6298#section-2.3. @@ -458,17 +370,17 @@ func (s *sender) updateRTO(rtt time.Duration) { alphaPrime := alpha / expectedSamples betaPrime := beta / expectedSamples - rttVar := (1-betaPrime)*s.rtt.rttvar.Seconds() + betaPrime*diff.Seconds() - srtt := (1-alphaPrime)*s.rtt.srtt.Seconds() + alphaPrime*rtt.Seconds() - s.rtt.rttvar = time.Duration(rttVar * float64(time.Second)) - s.rtt.srtt = time.Duration(srtt * float64(time.Second)) + rttVar := (1-betaPrime)*s.rtt.TCPRTTState.RTTVar.Seconds() + betaPrime*diff.Seconds() + srtt := (1-alphaPrime)*s.rtt.TCPRTTState.SRTT.Seconds() + alphaPrime*rtt.Seconds() + s.rtt.TCPRTTState.RTTVar = time.Duration(rttVar * float64(time.Second)) + s.rtt.TCPRTTState.SRTT = time.Duration(srtt * float64(time.Second)) } } - s.rto = s.rtt.srtt + 4*s.rtt.rttvar + s.RTO = s.rtt.TCPRTTState.SRTT + 4*s.rtt.TCPRTTState.RTTVar s.rtt.Unlock() - if s.rto < s.minRTO { - s.rto = s.minRTO + if s.RTO < s.minRTO { + s.RTO = s.minRTO } } @@ -476,20 +388,20 @@ func (s *sender) updateRTO(rtt time.Duration) { func (s *sender) resendSegment() { // Don't use any segments we already sent to measure RTT as they may // have been affected by packets being lost. - s.rttMeasureSeqNum = s.sndNxt + s.RTTMeasureSeqNum = s.SndNxt // Resend the segment. if seg := s.writeList.Front(); seg != nil { - if seg.data.Size() > s.maxPayloadSize { - s.splitSeg(seg, s.maxPayloadSize) + if seg.data.Size() > s.MaxPayloadSize { + s.splitSeg(seg, s.MaxPayloadSize) } // See: RFC 6675 section 5 Step 4.3 // // To prevent retransmission, set both the HighRXT and RescueRXT // to the highest sequence number in the retransmitted segment. - s.fr.highRxt = seg.sequenceNumber.Add(seqnum.Size(seg.data.Size())) - 1 - s.fr.rescueRxt = seg.sequenceNumber.Add(seqnum.Size(seg.data.Size())) - 1 + s.FastRecovery.HighRxt = seg.sequenceNumber.Add(seqnum.Size(seg.data.Size())) - 1 + s.FastRecovery.RescueRxt = seg.sequenceNumber.Add(seqnum.Size(seg.data.Size())) - 1 s.sendSegment(seg) s.ep.stack.Stats().TCP.FastRetransmit.Increment() s.ep.stats.SendErrors.FastRetransmit.Increment() @@ -554,15 +466,15 @@ func (s *sender) retransmitTimerExpired() bool { // Set new timeout. The timer will be restarted by the call to sendData // below. - s.rto *= 2 + s.RTO *= 2 // Cap the RTO as per RFC 1122 4.2.3.1, RFC 6298 5.5 - if s.rto > s.maxRTO { - s.rto = s.maxRTO + if s.RTO > s.maxRTO { + s.RTO = s.maxRTO } // Cap RTO to remaining time. - if s.rto > remaining { - s.rto = remaining + if s.RTO > remaining { + s.RTO = remaining } // See: https://tools.ietf.org/html/rfc6582#section-3.2 Step 4. @@ -571,9 +483,9 @@ func (s *sender) retransmitTimerExpired() bool { // After a retransmit timeout, record the highest sequence number // transmitted in the variable recover, and exit the fast recovery // procedure if applicable. - s.fr.last = s.sndNxt - 1 + s.FastRecovery.Last = s.SndNxt - 1 - if s.fr.active { + if s.FastRecovery.Active { // We were attempting fast recovery but were not successful. // Leave the state. We don't need to update ssthresh because it // has already been updated when entered fast-recovery. @@ -589,7 +501,7 @@ func (s *sender) retransmitTimerExpired() bool { // // We'll keep on transmitting (or retransmitting) as we get acks for // the data we transmit. - s.outstanding = 0 + s.Outstanding = 0 // Expunge all SACK information as per https://tools.ietf.org/html/rfc6675#section-5.1 // @@ -663,7 +575,7 @@ func (s *sender) splitSeg(seg *segment, size int) { // window space. // ref: net/ipv4/tcp_output.c::tcp_write_xmit(), tcp_mss_split_point() // ref: net/ipv4/tcp_output.c::tcp_write_wakeup(), tcp_snd_wnd_test() - if seg.data.Size() > s.maxPayloadSize { + if seg.data.Size() > s.MaxPayloadSize { seg.flags ^= header.TCPFlagPsh } @@ -689,7 +601,7 @@ func (s *sender) NextSeg(nextSegHint *segment) (nextSeg, hint *segment, rescueRt // transmitted (i.e. either it has no assigned sequence number // or if it does have one, it's >= the next sequence number // to be sent [i.e. >= s.sndNxt]). - if !s.isAssignedSequenceNumber(seg) || s.sndNxt.LessThanEq(seg.sequenceNumber) { + if !s.isAssignedSequenceNumber(seg) || s.SndNxt.LessThanEq(seg.sequenceNumber) { hint = nil break } @@ -710,7 +622,7 @@ func (s *sender) NextSeg(nextSegHint *segment) (nextSeg, hint *segment, rescueRt // (1.a) S2 is greater than HighRxt // (1.b) S2 is less than highest octect covered by // any received SACK. - if s.fr.highRxt.LessThan(segSeq) && segSeq.LessThan(s.ep.scoreboard.maxSACKED) { + if s.FastRecovery.HighRxt.LessThan(segSeq) && segSeq.LessThan(s.ep.scoreboard.maxSACKED) { // NextSeg(): // (1.c) IsLost(S2) returns true. if s.ep.scoreboard.IsLost(segSeq) { @@ -743,7 +655,7 @@ func (s *sender) NextSeg(nextSegHint *segment) (nextSeg, hint *segment, rescueRt // unSACKed sequence number SHOULD be returned, and // RescueRxt set to RecoveryPoint. HighRxt MUST NOT // be updated. - if s.fr.rescueRxt.LessThan(s.sndUna - 1) { + if s.FastRecovery.RescueRxt.LessThan(s.SndUna - 1) { if s4 != nil { if s4.sequenceNumber.LessThan(segSeq) { s4 = seg @@ -763,7 +675,7 @@ func (s *sender) NextSeg(nextSegHint *segment) (nextSeg, hint *segment, rescueRt // previously unsent data starting with sequence number // HighData+1 MUST be returned." for seg := s.writeNext; seg != nil; seg = seg.Next() { - if s.isAssignedSequenceNumber(seg) && seg.sequenceNumber.LessThan(s.sndNxt) { + if s.isAssignedSequenceNumber(seg) && seg.sequenceNumber.LessThan(s.SndNxt) { continue } // We do not split the segment here to <= smss as it has @@ -788,7 +700,7 @@ func (s *sender) maybeSendSegment(seg *segment, limit int, end seqnum.Value) (se if !s.isAssignedSequenceNumber(seg) { // Merge segments if allowed. if seg.data.Size() != 0 { - available := int(s.sndNxt.Size(end)) + available := int(s.SndNxt.Size(end)) if available > limit { available = limit } @@ -816,7 +728,7 @@ func (s *sender) maybeSendSegment(seg *segment, limit int, end seqnum.Value) (se } if !nextTooBig && seg.data.Size() < available { // Segment is not full. - if s.outstanding > 0 && s.ep.ops.GetDelayOption() { + if s.Outstanding > 0 && s.ep.ops.GetDelayOption() { // Nagle's algorithm. From Wikipedia: // Nagle's algorithm works by // combining a number of small @@ -835,7 +747,7 @@ func (s *sender) maybeSendSegment(seg *segment, limit int, end seqnum.Value) (se // send space and MSS. // TODO(gvisor.dev/issue/2833): Drain the held segments after a // timeout. - if seg.data.Size() < s.maxPayloadSize && s.ep.ops.GetCorkOption() { + if seg.data.Size() < s.MaxPayloadSize && s.ep.ops.GetCorkOption() { return false } } @@ -843,7 +755,7 @@ func (s *sender) maybeSendSegment(seg *segment, limit int, end seqnum.Value) (se // Assign flags. We don't do it above so that we can merge // additional data if Nagle holds the segment. - seg.sequenceNumber = s.sndNxt + seg.sequenceNumber = s.SndNxt seg.flags = header.TCPFlagAck | header.TCPFlagPsh } @@ -893,12 +805,12 @@ func (s *sender) maybeSendSegment(seg *segment, limit int, end seqnum.Value) (se // the segment right here if there are no pending segments. If // there are pending segments, segment transmits are deferred to // the retransmit timer handler. - if s.sndUna != s.sndNxt { + if s.SndUna != s.SndNxt { switch { case available >= seg.data.Size(): // OK to send, the whole segments fits in the // receiver's advertised window. - case available >= s.maxPayloadSize: + case available >= s.MaxPayloadSize: // OK to send, at least 1 MSS sized segment fits // in the receiver's advertised window. default: @@ -918,8 +830,8 @@ func (s *sender) maybeSendSegment(seg *segment, limit int, end seqnum.Value) (se // If GSO is not in use then cap available to // maxPayloadSize. When GSO is in use the gVisor GSO logic or // the host GSO logic will cap the segment to the correct size. - if s.ep.gso == nil && available > s.maxPayloadSize { - available = s.maxPayloadSize + if s.ep.gso == nil && available > s.MaxPayloadSize { + available = s.MaxPayloadSize } if seg.data.Size() > available { @@ -933,8 +845,8 @@ func (s *sender) maybeSendSegment(seg *segment, limit int, end seqnum.Value) (se // Update sndNxt if we actually sent new data (as opposed to // retransmitting some previously sent data). - if s.sndNxt.LessThan(segEnd) { - s.sndNxt = segEnd + if s.SndNxt.LessThan(segEnd) { + s.SndNxt = segEnd } return true @@ -945,9 +857,9 @@ func (s *sender) sendZeroWindowProbe() { s.unackZeroWindowProbes++ // Send a zero window probe with sequence number pointing to // the last acknowledged byte. - s.ep.sendRaw(buffer.VectorisedView{}, header.TCPFlagAck, s.sndUna-1, ack, win) + s.ep.sendRaw(buffer.VectorisedView{}, header.TCPFlagAck, s.SndUna-1, ack, win) // Rearm the timer to continue probing. - s.resendTimer.enable(s.rto) + s.resendTimer.enable(s.RTO) } func (s *sender) enableZeroWindowProbing() { @@ -958,7 +870,7 @@ func (s *sender) enableZeroWindowProbing() { if s.firstRetransmittedSegXmitTime.IsZero() { s.firstRetransmittedSegXmitTime = time.Now() } - s.resendTimer.enable(s.rto) + s.resendTimer.enable(s.RTO) } func (s *sender) disableZeroWindowProbing() { @@ -978,12 +890,12 @@ func (s *sender) postXmit(dataSent bool, shouldScheduleProbe bool) { // If the sender has advertized zero receive window and we have // data to be sent out, start zero window probing to query the // the remote for it's receive window size. - if s.writeNext != nil && s.sndWnd == 0 { + if s.writeNext != nil && s.SndWnd == 0 { s.enableZeroWindowProbing() } // If we have no more pending data, start the keepalive timer. - if s.sndUna == s.sndNxt { + if s.SndUna == s.SndNxt { s.ep.resetKeepaliveTimer(false) } else { // Enable timers if we have pending data. @@ -992,10 +904,10 @@ func (s *sender) postXmit(dataSent bool, shouldScheduleProbe bool) { s.schedulePTO() } else if !s.resendTimer.enabled() { s.probeTimer.disable() - if s.outstanding > 0 { + if s.Outstanding > 0 { // Enable the resend timer if it's not enabled yet and there is // outstanding data. - s.resendTimer.enable(s.rto) + s.resendTimer.enable(s.RTO) } } } @@ -1004,29 +916,29 @@ func (s *sender) postXmit(dataSent bool, shouldScheduleProbe bool) { // sendData sends new data segments. It is called when data becomes available or // when the send window opens up. func (s *sender) sendData() { - limit := s.maxPayloadSize + limit := s.MaxPayloadSize if s.gso { limit = int(s.ep.gso.MaxSize - header.TCPHeaderMaximumSize) } - end := s.sndUna.Add(s.sndWnd) + end := s.SndUna.Add(s.SndWnd) // Reduce the congestion window to min(IW, cwnd) per RFC 5681, page 10. // "A TCP SHOULD set cwnd to no more than RW before beginning // transmission if the TCP has not sent data in the interval exceeding // the retrasmission timeout." - if !s.fr.active && s.state != tcpip.RTORecovery && time.Now().Sub(s.lastSendTime) > s.rto { - if s.sndCwnd > InitialCwnd { - s.sndCwnd = InitialCwnd + if !s.FastRecovery.Active && s.state != tcpip.RTORecovery && time.Now().Sub(s.LastSendTime) > s.RTO { + if s.SndCwnd > InitialCwnd { + s.SndCwnd = InitialCwnd } } var dataSent bool - for seg := s.writeNext; seg != nil && s.outstanding < s.sndCwnd; seg = seg.Next() { - cwndLimit := (s.sndCwnd - s.outstanding) * s.maxPayloadSize + for seg := s.writeNext; seg != nil && s.Outstanding < s.SndCwnd; seg = seg.Next() { + cwndLimit := (s.SndCwnd - s.Outstanding) * s.MaxPayloadSize if cwndLimit < limit { limit = cwndLimit } - if s.isAssignedSequenceNumber(seg) && s.ep.sackPermitted && s.ep.scoreboard.IsSACKED(seg.sackBlock()) { + if s.isAssignedSequenceNumber(seg) && s.ep.SACKPermitted && s.ep.scoreboard.IsSACKED(seg.sackBlock()) { // Move writeNext along so that we don't try and scan data that // has already been SACKED. s.writeNext = seg.Next() @@ -1036,7 +948,7 @@ func (s *sender) sendData() { break } dataSent = true - s.outstanding += s.pCount(seg, s.maxPayloadSize) + s.Outstanding += s.pCount(seg, s.MaxPayloadSize) s.writeNext = seg.Next() } @@ -1044,21 +956,21 @@ func (s *sender) sendData() { } func (s *sender) enterRecovery() { - s.fr.active = true + s.FastRecovery.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 inflate the cwnd by 3 to account for the 3 packets which triggered // the 3 duplicate ACKs and are now not in flight. - s.sndCwnd = s.sndSsthresh + 3 - s.sackedOut = 0 - s.dupAckCount = 0 - s.fr.first = s.sndUna - s.fr.last = s.sndNxt - 1 - s.fr.maxCwnd = s.sndCwnd + s.outstanding - s.fr.highRxt = s.sndUna - s.fr.rescueRxt = s.sndUna - if s.ep.sackPermitted { + s.SndCwnd = s.Ssthresh + 3 + s.SackedOut = 0 + s.DupAckCount = 0 + s.FastRecovery.First = s.SndUna + s.FastRecovery.Last = s.SndNxt - 1 + s.FastRecovery.MaxCwnd = s.SndCwnd + s.Outstanding + s.FastRecovery.HighRxt = s.SndUna + s.FastRecovery.RescueRxt = s.SndUna + if s.ep.SACKPermitted { s.state = tcpip.SACKRecovery s.ep.stack.Stats().TCP.SACKRecovery.Increment() // Set TLPRxtOut to false according to @@ -1075,12 +987,12 @@ func (s *sender) enterRecovery() { } func (s *sender) leaveRecovery() { - s.fr.active = false - s.fr.maxCwnd = 0 - s.dupAckCount = 0 + s.FastRecovery.Active = false + s.FastRecovery.MaxCwnd = 0 + s.DupAckCount = 0 // Deflate cwnd. It had been artificially inflated when new dups arrived. - s.sndCwnd = s.sndSsthresh + s.SndCwnd = s.Ssthresh s.cc.PostRecovery() } @@ -1099,7 +1011,7 @@ func (s *sender) isAssignedSequenceNumber(seg *segment) bool { func (s *sender) SetPipe() { // If SACK isn't permitted or it is permitted but recovery is not active // then ignore pipe calculations. - if !s.ep.sackPermitted || !s.fr.active { + if !s.ep.SACKPermitted || !s.FastRecovery.Active { return } pipe := 0 @@ -1119,7 +1031,7 @@ func (s *sender) SetPipe() { // After initializing pipe to zero, the following steps are // taken for each octet 'S1' in the sequence space between // HighACK and HighData that has not been SACKed: - if !s1.sequenceNumber.LessThan(s.sndNxt) { + if !s1.sequenceNumber.LessThan(s.SndNxt) { break } if s.ep.scoreboard.IsSACKED(sb) { @@ -1138,20 +1050,20 @@ func (s *sender) SetPipe() { } // SetPipe(): // (b) If S1 <= HighRxt, Pipe is incremented by 1. - if s1.sequenceNumber.LessThanEq(s.fr.highRxt) { + if s1.sequenceNumber.LessThanEq(s.FastRecovery.HighRxt) { pipe++ } } } - s.outstanding = pipe + s.Outstanding = pipe } // shouldEnterRecovery returns true if the sender should enter fast recovery // based on dupAck count and sack scoreboard. // See RFC 6675 section 5. func (s *sender) shouldEnterRecovery() bool { - return s.dupAckCount >= nDupAckThreshold || - (s.ep.sackPermitted && s.ep.tcpRecovery&tcpip.TCPRACKLossDetection == 0 && s.ep.scoreboard.IsLost(s.sndUna)) + return s.DupAckCount >= nDupAckThreshold || + (s.ep.SACKPermitted && s.ep.tcpRecovery&tcpip.TCPRACKLossDetection == 0 && s.ep.scoreboard.IsLost(s.SndUna)) } // detectLoss is called when an ack is received and returns whether a loss is @@ -1163,24 +1075,24 @@ func (s *sender) detectLoss(seg *segment) (fastRetransmit bool) { // If RACK is enabled and there is no reordering we should honor the // three duplicate ACK rule to enter recovery. // See: https://tools.ietf.org/html/draft-ietf-tcpm-rack-08#section-4 - if s.ep.sackPermitted && s.ep.tcpRecovery&tcpip.TCPRACKLossDetection != 0 { - if s.rc.reorderSeen { + if s.ep.SACKPermitted && s.ep.tcpRecovery&tcpip.TCPRACKLossDetection != 0 { + if s.rc.Reord { return false } } if !s.isDupAck(seg) { - s.dupAckCount = 0 + s.DupAckCount = 0 return false } - s.dupAckCount++ + s.DupAckCount++ // Do not enter fast recovery until we reach nDupAckThreshold or the // first unacknowledged byte is considered lost as per SACK scoreboard. if !s.shouldEnterRecovery() { // RFC 6675 Step 3. - s.fr.highRxt = s.sndUna - 1 + s.FastRecovery.HighRxt = s.SndUna - 1 // Do run SetPipe() to calculate the outstanding segments. s.SetPipe() s.state = tcpip.Disorder @@ -1196,8 +1108,8 @@ func (s *sender) detectLoss(seg *segment) (fastRetransmit bool) { // Note that we only enter recovery when at least one more byte of data // beyond s.fr.last (the highest byte that was outstanding when fast // retransmit was last entered) is acked. - if !s.fr.last.LessThan(seg.ackNumber - 1) { - s.dupAckCount = 0 + if !s.FastRecovery.Last.LessThan(seg.ackNumber - 1) { + s.DupAckCount = 0 return false } s.cc.HandleLossDetected() @@ -1212,22 +1124,22 @@ func (s *sender) isDupAck(seg *segment) bool { // can leverage the SACK information to determine when an incoming ACK is a // "duplicate" (e.g., if the ACK contains previously unknown SACK // information). - if s.ep.sackPermitted && !seg.hasNewSACKInfo { + if s.ep.SACKPermitted && !seg.hasNewSACKInfo { return false } // (a) The receiver of the ACK has outstanding data. - return s.sndUna != s.sndNxt && + return s.SndUna != s.SndNxt && // (b) The incoming acknowledgment carries no data. seg.logicalLen() == 0 && // (c) The SYN and FIN bits are both off. !seg.flagIsSet(header.TCPFlagFin) && !seg.flagIsSet(header.TCPFlagSyn) && // (d) the ACK number is equal to the greatest acknowledgment received on // the given connection (TCP.UNA from RFC793). - seg.ackNumber == s.sndUna && + seg.ackNumber == s.SndUna && // (e) the advertised window in the incoming acknowledgment equals the // advertised window in the last incoming acknowledgment. - s.sndWnd == seg.window + s.SndWnd == seg.window } // Iterate the writeList and update RACK for each segment which is newly acked @@ -1267,7 +1179,7 @@ func (s *sender) walkSACK(rcvdSeg *segment) { s.rc.update(seg, rcvdSeg) s.rc.detectReorder(seg) seg.acked = true - s.sackedOut += s.pCount(seg, s.maxPayloadSize) + s.SackedOut += s.pCount(seg, s.MaxPayloadSize) } seg = seg.Next() } @@ -1322,18 +1234,18 @@ func checkDSACK(rcvdSeg *segment) bool { // updating the send-related state. func (s *sender) handleRcvdSegment(rcvdSeg *segment) { // Check if we can extract an RTT measurement from this ack. - if !rcvdSeg.parsedOptions.TS && s.rttMeasureSeqNum.LessThan(rcvdSeg.ackNumber) { - s.updateRTO(time.Now().Sub(s.rttMeasureTime)) - s.rttMeasureSeqNum = s.sndNxt + if !rcvdSeg.parsedOptions.TS && s.RTTMeasureSeqNum.LessThan(rcvdSeg.ackNumber) { + s.updateRTO(time.Now().Sub(s.RTTMeasureTime)) + s.RTTMeasureSeqNum = s.SndNxt } // Update Timestamp if required. See RFC7323, section-4.3. - if s.ep.sendTSOk && rcvdSeg.parsedOptions.TS { - s.ep.updateRecentTimestamp(rcvdSeg.parsedOptions.TSVal, s.maxSentAck, rcvdSeg.sequenceNumber) + if s.ep.SendTSOk && rcvdSeg.parsedOptions.TS { + s.ep.updateRecentTimestamp(rcvdSeg.parsedOptions.TSVal, s.MaxSentAck, rcvdSeg.sequenceNumber) } // Insert SACKBlock information into our scoreboard. - if s.ep.sackPermitted { + if s.ep.SACKPermitted { for _, sb := range rcvdSeg.parsedOptions.SACKBlocks { // Only insert the SACK block if the following holds // true: @@ -1347,7 +1259,7 @@ func (s *sender) handleRcvdSegment(rcvdSeg *segment) { // NOTE: This check specifically excludes DSACK blocks // which have start/end before sndUna and are used to // indicate spurious retransmissions. - if rcvdSeg.ackNumber.LessThan(sb.Start) && s.sndUna.LessThan(sb.Start) && sb.End.LessThanEq(s.sndNxt) && !s.ep.scoreboard.IsSACKED(sb) { + if rcvdSeg.ackNumber.LessThan(sb.Start) && s.SndUna.LessThan(sb.Start) && sb.End.LessThanEq(s.SndNxt) && !s.ep.scoreboard.IsSACKED(sb) { s.ep.scoreboard.Insert(sb) rcvdSeg.hasNewSACKInfo = true } @@ -1375,10 +1287,10 @@ func (s *sender) handleRcvdSegment(rcvdSeg *segment) { ack := rcvdSeg.ackNumber fastRetransmit := false // Do not leave fast recovery, if the ACK is out of range. - if s.fr.active { + if s.FastRecovery.Active { // Leave fast recovery if it acknowledges all the data covered by // this fast recovery session. - if (ack-1).InRange(s.sndUna, s.sndNxt) && s.fr.last.LessThan(ack) { + if (ack-1).InRange(s.SndUna, s.SndNxt) && s.FastRecovery.Last.LessThan(ack) { s.leaveRecovery() } } else { @@ -1392,28 +1304,28 @@ func (s *sender) handleRcvdSegment(rcvdSeg *segment) { } // Stash away the current window size. - s.sndWnd = rcvdSeg.window + s.SndWnd = rcvdSeg.window // Disable zero window probing if remote advertizes a non-zero receive // window. This can be with an ACK to the zero window probe (where the // acknumber refers to the already acknowledged byte) OR to any previously // unacknowledged segment. if s.zeroWindowProbing && rcvdSeg.window > 0 && - (ack == s.sndUna || (ack-1).InRange(s.sndUna, s.sndNxt)) { + (ack == s.SndUna || (ack-1).InRange(s.SndUna, s.SndNxt)) { s.disableZeroWindowProbing() } // On receiving the ACK for the zero window probe, account for it and // skip trying to send any segment as we are still probing for // receive window to become non-zero. - if s.zeroWindowProbing && s.unackZeroWindowProbes > 0 && ack == s.sndUna { + if s.zeroWindowProbing && s.unackZeroWindowProbes > 0 && ack == s.SndUna { s.unackZeroWindowProbes-- return } // Ignore ack if it doesn't acknowledge any new data. - if (ack - 1).InRange(s.sndUna, s.sndNxt) { - s.dupAckCount = 0 + if (ack - 1).InRange(s.SndUna, s.SndNxt) { + s.DupAckCount = 0 // See : https://tools.ietf.org/html/rfc1323#section-3.3. // Specifically we should only update the RTO using TSEcr if the @@ -1423,7 +1335,7 @@ func (s *sender) handleRcvdSegment(rcvdSeg *segment) { // 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 && rcvdSeg.parsedOptions.TSEcr != 0 { + if s.ep.SendTSOk && rcvdSeg.parsedOptions.TSEcr != 0 { // TSVal/Ecr values sent by Netstack are at a millisecond // granularity. elapsed := time.Duration(s.ep.timestamp()-rcvdSeg.parsedOptions.TSEcr) * time.Millisecond @@ -1438,12 +1350,12 @@ func (s *sender) handleRcvdSegment(rcvdSeg *segment) { // When an ack is received we must rearm the timer. // RFC 6298 5.3 s.probeTimer.disable() - s.resendTimer.enable(s.rto) + s.resendTimer.enable(s.RTO) } // Remove all acknowledged data from the write list. - acked := s.sndUna.Size(ack) - s.sndUna = ack + acked := s.SndUna.Size(ack) + s.SndUna = ack // The remote ACK-ing at least 1 byte is an indication that we have a // full-duplex connection to the remote as the only way we will receive an @@ -1457,7 +1369,7 @@ func (s *sender) handleRcvdSegment(rcvdSeg *segment) { } ackLeft := acked - originalOutstanding := s.outstanding + originalOutstanding := s.Outstanding for ackLeft > 0 { // We use logicalLen here because we can have FIN // segments (which are always at the end of list) that @@ -1466,10 +1378,10 @@ func (s *sender) handleRcvdSegment(rcvdSeg *segment) { datalen := seg.logicalLen() if datalen > ackLeft { - prevCount := s.pCount(seg, s.maxPayloadSize) + prevCount := s.pCount(seg, s.MaxPayloadSize) seg.data.TrimFront(int(ackLeft)) seg.sequenceNumber.UpdateForward(ackLeft) - s.outstanding -= prevCount - s.pCount(seg, s.maxPayloadSize) + s.Outstanding -= prevCount - s.pCount(seg, s.MaxPayloadSize) break } @@ -1478,7 +1390,7 @@ func (s *sender) handleRcvdSegment(rcvdSeg *segment) { } // Update the RACK fields if SACK is enabled. - if s.ep.sackPermitted && !seg.acked && s.ep.tcpRecovery&tcpip.TCPRACKLossDetection != 0 { + if s.ep.SACKPermitted && !seg.acked && s.ep.tcpRecovery&tcpip.TCPRACKLossDetection != 0 { s.rc.update(seg, rcvdSeg) s.rc.detectReorder(seg) } @@ -1488,10 +1400,10 @@ func (s *sender) handleRcvdSegment(rcvdSeg *segment) { // If SACK is enabled then only reduce outstanding if // the segment was not previously SACKED as these have // already been accounted for in SetPipe(). - if !s.ep.sackPermitted || !s.ep.scoreboard.IsSACKED(seg.sackBlock()) { - s.outstanding -= s.pCount(seg, s.maxPayloadSize) + if !s.ep.SACKPermitted || !s.ep.scoreboard.IsSACKED(seg.sackBlock()) { + s.Outstanding -= s.pCount(seg, s.MaxPayloadSize) } else { - s.sackedOut -= s.pCount(seg, s.maxPayloadSize) + s.SackedOut -= s.pCount(seg, s.MaxPayloadSize) } seg.decRef() ackLeft -= datalen @@ -1501,13 +1413,13 @@ func (s *sender) handleRcvdSegment(rcvdSeg *segment) { s.ep.updateSndBufferUsage(int(acked)) // Clear SACK information for all acked data. - s.ep.scoreboard.Delete(s.sndUna) + s.ep.scoreboard.Delete(s.SndUna) // If we are not in fast recovery then update the congestion // window based on the number of acknowledged packets. - if !s.fr.active { - s.cc.Update(originalOutstanding - s.outstanding) - if s.fr.last.LessThan(s.sndUna) { + if !s.FastRecovery.Active { + s.cc.Update(originalOutstanding - s.Outstanding) + if s.FastRecovery.Last.LessThan(s.SndUna) { s.state = tcpip.Open // Update RACK when we are exiting fast or RTO // recovery as described in the RFC @@ -1522,16 +1434,16 @@ func (s *sender) handleRcvdSegment(rcvdSeg *segment) { // It is possible for s.outstanding to drop below zero if we get // a retransmit timeout, reset outstanding to zero but later // get an ack that cover previously sent data. - if s.outstanding < 0 { - s.outstanding = 0 + if s.Outstanding < 0 { + s.Outstanding = 0 } s.SetPipe() // If all outstanding data was acknowledged the disable the timer. // RFC 6298 Rule 5.3 - if s.sndUna == s.sndNxt { - s.outstanding = 0 + if s.SndUna == s.SndNxt { + s.Outstanding = 0 // Reset firstRetransmittedSegXmitTime to the zero value. s.firstRetransmittedSegXmitTime = time.Time{} s.resendTimer.disable() @@ -1539,7 +1451,7 @@ func (s *sender) handleRcvdSegment(rcvdSeg *segment) { } } - if s.ep.sackPermitted && s.ep.tcpRecovery&tcpip.TCPRACKLossDetection != 0 { + if s.ep.SACKPermitted && s.ep.tcpRecovery&tcpip.TCPRACKLossDetection != 0 { // Update RACK reorder window. // See: https://tools.ietf.org/html/draft-ietf-tcpm-rack-08#section-7.2 // * Upon receiving an ACK: @@ -1549,7 +1461,7 @@ func (s *sender) handleRcvdSegment(rcvdSeg *segment) { // After the reorder window is calculated, detect any loss by checking // if the time elapsed after the segments are sent is greater than the // reorder window. - if numLost := s.rc.detectLoss(rcvdSeg.rcvdTime); numLost > 0 && !s.fr.active { + if numLost := s.rc.detectLoss(rcvdSeg.rcvdTime); numLost > 0 && !s.FastRecovery.Active { // If any segment is marked as lost by // RACK, enter recovery and retransmit // the lost segments. @@ -1558,19 +1470,19 @@ func (s *sender) handleRcvdSegment(rcvdSeg *segment) { fastRetransmit = true } - if s.fr.active { + if s.FastRecovery.Active { s.rc.DoRecovery(nil, fastRetransmit) } } // Now that we've popped all acknowledged data from the retransmit // queue, retransmit if needed. - if s.fr.active && s.ep.tcpRecovery&tcpip.TCPRACKLossDetection == 0 { + if s.FastRecovery.Active && s.ep.tcpRecovery&tcpip.TCPRACKLossDetection == 0 { s.lr.DoRecovery(rcvdSeg, fastRetransmit) // When SACK is enabled data sending is governed by steps in // RFC 6675 Section 5 recovery steps A-C. // See: https://tools.ietf.org/html/rfc6675#section-5. - if s.ep.sackPermitted { + if s.ep.SACKPermitted { return } } @@ -1587,7 +1499,7 @@ func (s *sender) sendSegment(seg *segment) tcpip.Error { if seg.xmitCount > 0 { s.ep.stack.Stats().TCP.Retransmits.Increment() s.ep.stats.SendErrors.Retransmits.Increment() - if s.sndCwnd < s.sndSsthresh { + if s.SndCwnd < s.Ssthresh { s.ep.stack.Stats().TCP.SlowStartRetransmits.Increment() } } @@ -1601,11 +1513,11 @@ func (s *sender) sendSegment(seg *segment) tcpip.Error { // then use the conservative timer described in RFC6675 Section 6.0, // otherwise follow the standard time described in RFC6298 Section 5.1. if err != nil && seg.data.Size() != 0 { - if s.fr.active && seg.xmitCount > 1 && s.ep.sackPermitted { - s.resendTimer.enable(s.rto) + if s.FastRecovery.Active && seg.xmitCount > 1 && s.ep.SACKPermitted { + s.resendTimer.enable(s.RTO) } else { if !s.resendTimer.enabled() { - s.resendTimer.enable(s.rto) + s.resendTimer.enable(s.RTO) } } } @@ -1616,15 +1528,15 @@ func (s *sender) sendSegment(seg *segment) tcpip.Error { // sendSegmentFromView sends a new segment containing the given payload, flags // and sequence number. func (s *sender) sendSegmentFromView(data buffer.VectorisedView, flags header.TCPFlags, seq seqnum.Value) tcpip.Error { - s.lastSendTime = time.Now() - if seq == s.rttMeasureSeqNum { - s.rttMeasureTime = s.lastSendTime + s.LastSendTime = time.Now() + if seq == s.RTTMeasureSeqNum { + s.RTTMeasureTime = s.LastSendTime } rcvNxt, rcvWnd := s.ep.rcv.getSendParams() // Remember the max sent ack. - s.maxSentAck = rcvNxt + s.MaxSentAck = rcvNxt return s.ep.sendRaw(data, flags, seq, rcvNxt, rcvWnd) } |