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-rw-r--r--pkg/sentry/socket/netstack/netstack.go1
-rw-r--r--pkg/tcpip/tcpip.go4
-rw-r--r--pkg/tcpip/transport/tcp/snd.go7
3 files changed, 12 insertions, 0 deletions
diff --git a/pkg/sentry/socket/netstack/netstack.go b/pkg/sentry/socket/netstack/netstack.go
index 0f8cbe7e2..9b844b0c0 100644
--- a/pkg/sentry/socket/netstack/netstack.go
+++ b/pkg/sentry/socket/netstack/netstack.go
@@ -274,6 +274,7 @@ var Metrics = tcpip.Stats{
Timeouts: mustCreateMetric("/netstack/tcp/timeouts", "Number of times RTO expired."),
ChecksumErrors: mustCreateMetric("/netstack/tcp/checksum_errors", "Number of segments dropped due to bad checksums."),
FailedPortReservations: mustCreateMetric("/netstack/tcp/failed_port_reservations", "Number of time TCP failed to reserve a port."),
+ SegmentsAckedWithDSACK: mustCreateMetric("/netstack/tcp/segments_acked_with_dsack", "Number of segments for which DSACK was received."),
},
UDP: tcpip.UDPStats{
PacketsReceived: mustCreateMetric("/netstack/udp/packets_received", "Number of UDP datagrams received via HandlePacket."),
diff --git a/pkg/tcpip/tcpip.go b/pkg/tcpip/tcpip.go
index 8f2658f64..55683b4fb 100644
--- a/pkg/tcpip/tcpip.go
+++ b/pkg/tcpip/tcpip.go
@@ -1845,6 +1845,10 @@ type TCPStats struct {
// FailedPortReservations is the number of times TCP failed to reserve
// a port.
FailedPortReservations *StatCounter
+
+ // SegmentsAckedWithDSACK is the number of segments acknowledged with
+ // DSACK.
+ SegmentsAckedWithDSACK *StatCounter
}
// UDPStats collects UDP-specific stats.
diff --git a/pkg/tcpip/transport/tcp/snd.go b/pkg/tcpip/transport/tcp/snd.go
index 72d58dcff..92a66f17e 100644
--- a/pkg/tcpip/transport/tcp/snd.go
+++ b/pkg/tcpip/transport/tcp/snd.go
@@ -1154,6 +1154,13 @@ func (s *sender) walkSACK(rcvdSeg *segment) {
idx := 0
n := len(rcvdSeg.parsedOptions.SACKBlocks)
if checkDSACK(rcvdSeg) {
+ dsackBlock := rcvdSeg.parsedOptions.SACKBlocks[0]
+ numDSACK := uint64(dsackBlock.End-dsackBlock.Start) / uint64(s.MaxPayloadSize)
+ // numDSACK can be zero when DSACK is sent for subsegments.
+ if numDSACK < 1 {
+ numDSACK = 1
+ }
+ s.ep.stack.Stats().TCP.SegmentsAckedWithDSACK.IncrementBy(numDSACK)
s.rc.setDSACKSeen(true)
idx = 1
n--