diff options
| -rw-r--r-- | pkg/tcpip/transport/tcp/endpoint.go | 1 | ||||
| -rw-r--r-- | pkg/tcpip/transport/tcp/rack.go | 40 | ||||
| -rw-r--r-- | pkg/tcpip/transport/tcp/segment.go | 3 | ||||
| -rw-r--r-- | pkg/tcpip/transport/tcp/snd.go | 59 | ||||
| -rw-r--r-- | pkg/tcpip/transport/tcp/tcp_state_autogen.go | 19 |
5 files changed, 109 insertions, 13 deletions
diff --git a/pkg/tcpip/transport/tcp/endpoint.go b/pkg/tcpip/transport/tcp/endpoint.go index ae817091a..bc3b409ba 100644 --- a/pkg/tcpip/transport/tcp/endpoint.go +++ b/pkg/tcpip/transport/tcp/endpoint.go @@ -3013,6 +3013,7 @@ func (e *endpoint) completeState() stack.TCPEndpointState { EndSequence: rc.endSequence, FACK: rc.fack, RTT: rc.rtt, + Reord: rc.reorderSeen, } return s } diff --git a/pkg/tcpip/transport/tcp/rack.go b/pkg/tcpip/transport/tcp/rack.go index 439932595..d312b1b8b 100644 --- a/pkg/tcpip/transport/tcp/rack.go +++ b/pkg/tcpip/transport/tcp/rack.go @@ -29,12 +29,12 @@ import ( // // +stateify savable type rackControl struct { - // xmitTime is the latest transmission timestamp of rackControl.seg. - xmitTime time.Time `state:".(unixTime)"` - // endSequence is the ending TCP sequence number of rackControl.seg. endSequence seqnum.Value + // dsack indicates if the connection has seen a DSACK. + dsack bool + // fack is the highest selectively or cumulatively acknowledged // sequence. fack seqnum.Value @@ -47,11 +47,18 @@ type rackControl struct { // acknowledged) that was not marked invalid as a possible spurious // retransmission. rtt time.Duration + + // reorderSeen indicates if reordering has been detected on this + // connection. + reorderSeen bool + + // xmitTime is the latest transmission timestamp of rackControl.seg. + xmitTime time.Time `state:".(unixTime)"` } -// Update will update the RACK related fields when an ACK has been received. +// update will update the RACK related fields when an ACK has been received. // See: https://tools.ietf.org/html/draft-ietf-tcpm-rack-08#section-7.2 -func (rc *rackControl) Update(seg *segment, ackSeg *segment, offset uint32) { +func (rc *rackControl) update(seg *segment, ackSeg *segment, offset uint32) { rtt := time.Now().Sub(seg.xmitTime) // If the ACK is for a retransmitted packet, do not update if it is a @@ -92,3 +99,26 @@ func (rc *rackControl) Update(seg *segment, ackSeg *segment, offset uint32) { rc.endSequence = endSeq } } + +// detectReorder detects if packet reordering has been observed. +// See: https://tools.ietf.org/html/draft-ietf-tcpm-rack-08#section-7.2 +// * Step 3: Detect data segment reordering. +// To detect reordering, the sender looks for original data segments being +// delivered out of order. To detect such cases, the sender tracks the +// highest sequence selectively or cumulatively acknowledged in the RACK.fack +// variable. The name "fack" stands for the most "Forward ACK" (this term is +// adopted from [FACK]). If a never retransmitted segment that's below +// RACK.fack is (selectively or cumulatively) acknowledged, it has been +// delivered out of order. The sender sets RACK.reord to TRUE if such segment +// is identified. +func (rc *rackControl) detectReorder(seg *segment) { + endSeq := seg.sequenceNumber.Add(seqnum.Size(seg.data.Size())) + if rc.fack.LessThan(endSeq) { + rc.fack = endSeq + return + } + + if endSeq.LessThan(rc.fack) && seg.xmitCount == 1 { + rc.reorderSeen = true + } +} diff --git a/pkg/tcpip/transport/tcp/segment.go b/pkg/tcpip/transport/tcp/segment.go index 13acaf753..1f9c5cf50 100644 --- a/pkg/tcpip/transport/tcp/segment.go +++ b/pkg/tcpip/transport/tcp/segment.go @@ -71,6 +71,9 @@ type segment struct { // xmitTime is the last transmit time of this segment. xmitTime time.Time `state:".(unixTime)"` xmitCount uint32 + + // acked indicates if the segment has already been SACKed. + acked bool } func newSegment(r *stack.Route, id stack.TransportEndpointID, pkt *stack.PacketBuffer) *segment { diff --git a/pkg/tcpip/transport/tcp/snd.go b/pkg/tcpip/transport/tcp/snd.go index 4c9a86cda..6fa8d63cd 100644 --- a/pkg/tcpip/transport/tcp/snd.go +++ b/pkg/tcpip/transport/tcp/snd.go @@ -17,6 +17,7 @@ package tcp import ( "fmt" "math" + "sort" "sync/atomic" "time" @@ -263,6 +264,9 @@ func newSender(ep *endpoint, iss, irs seqnum.Value, sndWnd seqnum.Size, mss uint highRxt: iss, rescueRxt: iss, }, + rc: rackControl{ + fack: iss, + }, gso: ep.gso != nil, } @@ -1274,6 +1278,39 @@ func (s *sender) checkDuplicateAck(seg *segment) (rtx bool) { return true } +// Iterate the writeList and update RACK for each segment which is newly acked +// either cumulatively or selectively. Loop through the segments which are +// sacked, and update the RACK related variables and check for reordering. +// +// See: https://tools.ietf.org/html/draft-ietf-tcpm-rack-08#section-7.2 +// steps 2 and 3. +func (s *sender) walkSACK(rcvdSeg *segment) { + // Sort the SACK blocks. The first block is the most recent unacked + // block. The following blocks can be in arbitrary order. + sackBlocks := make([]header.SACKBlock, len(rcvdSeg.parsedOptions.SACKBlocks)) + copy(sackBlocks, rcvdSeg.parsedOptions.SACKBlocks) + sort.Slice(sackBlocks, func(i, j int) bool { + return sackBlocks[j].Start.LessThan(sackBlocks[i].Start) + }) + + seg := s.writeList.Front() + for _, sb := range sackBlocks { + // This check excludes DSACK blocks. + if sb.Start.LessThanEq(rcvdSeg.ackNumber) || sb.Start.LessThanEq(s.sndUna) || s.sndNxt.LessThan(sb.End) { + continue + } + + for seg != nil && seg.sequenceNumber.LessThan(sb.End) && seg.xmitCount != 0 { + if sb.Start.LessThanEq(seg.sequenceNumber) && !seg.acked { + s.rc.update(seg, rcvdSeg, s.ep.tsOffset) + s.rc.detectReorder(seg) + seg.acked = true + } + seg = seg.Next() + } + } +} + // handleRcvdSegment is called when a segment is received; it is responsible for // updating the send-related state. func (s *sender) handleRcvdSegment(rcvdSeg *segment) { @@ -1308,6 +1345,21 @@ func (s *sender) handleRcvdSegment(rcvdSeg *segment) { rcvdSeg.hasNewSACKInfo = true } } + + // See: https://tools.ietf.org/html/draft-ietf-tcpm-rack-08 + // section-7.2 + // * Step 2: Update RACK stats. + // If the ACK is not ignored as invalid, update the RACK.rtt + // to be the RTT sample calculated using this ACK, and + // continue. If this ACK or SACK was for the most recently + // sent packet, then record the RACK.xmit_ts timestamp and + // RACK.end_seq sequence implied by this ACK. + // * Step 3: Detect packet reordering. + // If the ACK selectively or cumulatively acknowledges an + // unacknowledged and also never retransmitted sequence below + // RACK.fack, then the corresponding packet has been + // reordered and RACK.reord is set to TRUE. + s.walkSACK(rcvdSeg) s.SetPipe() } @@ -1385,13 +1437,14 @@ func (s *sender) handleRcvdSegment(rcvdSeg *segment) { } // Update the RACK fields if SACK is enabled. - if s.ep.sackPermitted { - s.rc.Update(seg, rcvdSeg, s.ep.tsOffset) + if s.ep.sackPermitted && !seg.acked { + s.rc.update(seg, rcvdSeg, s.ep.tsOffset) + s.rc.detectReorder(seg) } s.writeList.Remove(seg) - // if SACK is enabled then Only reduce outstanding if + // 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()) { diff --git a/pkg/tcpip/transport/tcp/tcp_state_autogen.go b/pkg/tcpip/transport/tcp/tcp_state_autogen.go index be50ff9ff..5466ce660 100644 --- a/pkg/tcpip/transport/tcp/tcp_state_autogen.go +++ b/pkg/tcpip/transport/tcp/tcp_state_autogen.go @@ -408,11 +408,13 @@ func (rc *rackControl) StateTypeName() string { func (rc *rackControl) StateFields() []string { return []string{ - "xmitTime", "endSequence", + "dsack", "fack", "minRTT", "rtt", + "reorderSeen", + "xmitTime", } } @@ -421,21 +423,25 @@ func (rc *rackControl) beforeSave() {} func (rc *rackControl) StateSave(stateSinkObject state.Sink) { rc.beforeSave() var xmitTimeValue unixTime = rc.saveXmitTime() - stateSinkObject.SaveValue(0, xmitTimeValue) - stateSinkObject.Save(1, &rc.endSequence) + stateSinkObject.SaveValue(6, xmitTimeValue) + stateSinkObject.Save(0, &rc.endSequence) + stateSinkObject.Save(1, &rc.dsack) stateSinkObject.Save(2, &rc.fack) stateSinkObject.Save(3, &rc.minRTT) stateSinkObject.Save(4, &rc.rtt) + stateSinkObject.Save(5, &rc.reorderSeen) } func (rc *rackControl) afterLoad() {} func (rc *rackControl) StateLoad(stateSourceObject state.Source) { - stateSourceObject.Load(1, &rc.endSequence) + stateSourceObject.Load(0, &rc.endSequence) + stateSourceObject.Load(1, &rc.dsack) stateSourceObject.Load(2, &rc.fack) stateSourceObject.Load(3, &rc.minRTT) stateSourceObject.Load(4, &rc.rtt) - stateSourceObject.LoadValue(0, new(unixTime), func(y interface{}) { rc.loadXmitTime(y.(unixTime)) }) + stateSourceObject.Load(5, &rc.reorderSeen) + stateSourceObject.LoadValue(6, new(unixTime), func(y interface{}) { rc.loadXmitTime(y.(unixTime)) }) } func (r *receiver) StateTypeName() string { @@ -560,6 +566,7 @@ func (s *segment) StateFields() []string { "rcvdTime", "xmitTime", "xmitCount", + "acked", } } @@ -590,6 +597,7 @@ func (s *segment) StateSave(stateSinkObject state.Sink) { stateSinkObject.Save(13, &s.parsedOptions) stateSinkObject.Save(15, &s.hasNewSACKInfo) stateSinkObject.Save(18, &s.xmitCount) + stateSinkObject.Save(19, &s.acked) } func (s *segment) afterLoad() {} @@ -610,6 +618,7 @@ func (s *segment) StateLoad(stateSourceObject state.Source) { stateSourceObject.Load(13, &s.parsedOptions) stateSourceObject.Load(15, &s.hasNewSACKInfo) stateSourceObject.Load(18, &s.xmitCount) + stateSourceObject.Load(19, &s.acked) stateSourceObject.LoadValue(4, new(buffer.VectorisedView), func(y interface{}) { s.loadData(y.(buffer.VectorisedView)) }) stateSourceObject.LoadValue(14, new([]byte), func(y interface{}) { s.loadOptions(y.([]byte)) }) stateSourceObject.LoadValue(16, new(unixTime), func(y interface{}) { s.loadRcvdTime(y.(unixTime)) }) |