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-rw-r--r--pkg/tcpip/transport/tcp/endpoint.go1
-rw-r--r--pkg/tcpip/transport/tcp/rack.go40
-rw-r--r--pkg/tcpip/transport/tcp/segment.go3
-rw-r--r--pkg/tcpip/transport/tcp/snd.go59
-rw-r--r--pkg/tcpip/transport/tcp/tcp_rack_test.go75
-rw-r--r--pkg/tcpip/transport/tcp/testing/context/context.go12
6 files changed, 170 insertions, 20 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_rack_test.go b/pkg/tcpip/transport/tcp/tcp_rack_test.go
index e03f101e8..d3f92b48c 100644
--- a/pkg/tcpip/transport/tcp/tcp_rack_test.go
+++ b/pkg/tcpip/transport/tcp/tcp_rack_test.go
@@ -21,17 +21,20 @@ import (
"gvisor.dev/gvisor/pkg/tcpip"
"gvisor.dev/gvisor/pkg/tcpip/buffer"
"gvisor.dev/gvisor/pkg/tcpip/header"
+ "gvisor.dev/gvisor/pkg/tcpip/seqnum"
"gvisor.dev/gvisor/pkg/tcpip/stack"
"gvisor.dev/gvisor/pkg/tcpip/transport/tcp/testing/context"
)
+const (
+ maxPayload = 10
+ tsOptionSize = 12
+ maxTCPOptionSize = 40
+)
+
// TestRACKUpdate tests the RACK related fields are updated when an ACK is
// received on a SACK enabled connection.
func TestRACKUpdate(t *testing.T) {
- const maxPayload = 10
- const tsOptionSize = 12
- const maxTCPOptionSize = 40
-
c := context.New(t, uint32(header.TCPMinimumSize+header.IPv4MinimumSize+maxTCPOptionSize+maxPayload))
defer c.Cleanup()
@@ -49,7 +52,7 @@ func TestRACKUpdate(t *testing.T) {
}
if state.Sender.RACKState.RTT == 0 {
- t.Fatalf("RACK RTT failed to update when an ACK is received")
+ t.Fatalf("RACK RTT failed to update when an ACK is received, got RACKState.RTT == 0 want != 0")
}
})
setStackSACKPermitted(t, c, true)
@@ -69,6 +72,66 @@ func TestRACKUpdate(t *testing.T) {
bytesRead := 0
c.ReceiveAndCheckPacketWithOptions(data, bytesRead, maxPayload, tsOptionSize)
bytesRead += maxPayload
- c.SendAck(790, bytesRead)
+ c.SendAck(seqnum.Value(context.TestInitialSequenceNumber).Add(1), bytesRead)
time.Sleep(200 * time.Millisecond)
}
+
+// TestRACKDetectReorder tests that RACK detects packet reordering.
+func TestRACKDetectReorder(t *testing.T) {
+ c := context.New(t, uint32(header.TCPMinimumSize+header.IPv4MinimumSize+maxTCPOptionSize+maxPayload))
+ defer c.Cleanup()
+
+ const ackNum = 2
+
+ var n int
+ ch := make(chan struct{})
+ c.Stack().AddTCPProbe(func(state stack.TCPEndpointState) {
+ gotSeq := state.Sender.RACKState.FACK
+ wantSeq := state.Sender.SndNxt
+ // FACK should be updated to the highest ending sequence number of the
+ // segment acknowledged most recently.
+ if !gotSeq.LessThanEq(wantSeq) || gotSeq.LessThan(wantSeq) {
+ t.Fatalf("RACK FACK failed to update, got: %v, but want: %v", gotSeq, wantSeq)
+ }
+
+ n++
+ if n < ackNum {
+ if state.Sender.RACKState.Reord {
+ t.Fatalf("RACK reorder detected when there is no reordering")
+ }
+ return
+ }
+
+ if state.Sender.RACKState.Reord == false {
+ t.Fatalf("RACK reorder detection failed")
+ }
+ close(ch)
+ })
+ setStackSACKPermitted(t, c, true)
+ createConnectedWithSACKAndTS(c)
+ data := buffer.NewView(ackNum * maxPayload)
+ for i := range data {
+ data[i] = byte(i)
+ }
+
+ // Write the data.
+ if _, _, err := c.EP.Write(tcpip.SlicePayload(data), tcpip.WriteOptions{}); err != nil {
+ t.Fatalf("Write failed: %s", err)
+ }
+
+ bytesRead := 0
+ for i := 0; i < ackNum; i++ {
+ c.ReceiveAndCheckPacketWithOptions(data, bytesRead, maxPayload, tsOptionSize)
+ bytesRead += maxPayload
+ }
+
+ start := c.IRS.Add(maxPayload + 1)
+ end := start.Add(maxPayload)
+ seq := seqnum.Value(context.TestInitialSequenceNumber).Add(1)
+ c.SendAckWithSACK(seq, 0, []header.SACKBlock{{start, end}})
+ c.SendAck(seq, bytesRead)
+
+ // Wait for the probe function to finish processing the ACK before the
+ // test completes.
+ <-ch
+}
diff --git a/pkg/tcpip/transport/tcp/testing/context/context.go b/pkg/tcpip/transport/tcp/testing/context/context.go
index faf51ef95..4d7847142 100644
--- a/pkg/tcpip/transport/tcp/testing/context/context.go
+++ b/pkg/tcpip/transport/tcp/testing/context/context.go
@@ -68,9 +68,9 @@ const (
// V4MappedWildcardAddr is the mapped v6 representation of 0.0.0.0.
V4MappedWildcardAddr = "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\xff\xff\x00\x00\x00\x00"
- // testInitialSequenceNumber is the initial sequence number sent in packets that
+ // TestInitialSequenceNumber is the initial sequence number sent in packets that
// are sent in response to a SYN or in the initial SYN sent to the stack.
- testInitialSequenceNumber = 789
+ TestInitialSequenceNumber = 789
)
// StackAddrWithPrefix is StackAddr with its associated prefix length.
@@ -505,7 +505,7 @@ func (c *Context) ReceiveAndCheckPacketWithOptions(data []byte, offset, size, op
checker.TCP(
checker.DstPort(TestPort),
checker.TCPSeqNum(uint32(c.IRS.Add(seqnum.Size(1+offset)))),
- checker.TCPAckNum(uint32(seqnum.Value(testInitialSequenceNumber).Add(1))),
+ checker.TCPAckNum(uint32(seqnum.Value(TestInitialSequenceNumber).Add(1))),
checker.TCPFlagsMatch(header.TCPFlagAck, ^uint8(header.TCPFlagPsh)),
),
)
@@ -532,7 +532,7 @@ func (c *Context) ReceiveNonBlockingAndCheckPacket(data []byte, offset, size int
checker.TCP(
checker.DstPort(TestPort),
checker.TCPSeqNum(uint32(c.IRS.Add(seqnum.Size(1+offset)))),
- checker.TCPAckNum(uint32(seqnum.Value(testInitialSequenceNumber).Add(1))),
+ checker.TCPAckNum(uint32(seqnum.Value(TestInitialSequenceNumber).Add(1))),
checker.TCPFlagsMatch(header.TCPFlagAck, ^uint8(header.TCPFlagPsh)),
),
)
@@ -912,7 +912,7 @@ func (c *Context) CreateConnectedWithOptions(wantOptions header.TCPSynOptions) *
// Build SYN-ACK.
c.IRS = seqnum.Value(tcpSeg.SequenceNumber())
- iss := seqnum.Value(testInitialSequenceNumber)
+ iss := seqnum.Value(TestInitialSequenceNumber)
c.SendPacket(nil, &Headers{
SrcPort: tcpSeg.DestinationPort(),
DstPort: tcpSeg.SourcePort(),
@@ -1084,7 +1084,7 @@ func (c *Context) PassiveConnectWithOptions(maxPayload, wndScale int, synOptions
offset += paddingToAdd
// Send a SYN request.
- iss := seqnum.Value(testInitialSequenceNumber)
+ iss := seqnum.Value(TestInitialSequenceNumber)
c.SendPacket(nil, &Headers{
SrcPort: TestPort,
DstPort: StackPort,
generated by cgit v1.2.3 (git 2.39.1) at 2024-12-24 03:18:52 +0000