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Avoid a race with test peer advert and DUT send

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Fix a race where the DUT could send out test data before it received the
peer window advertisement. Such a race results in the DUT taking longer
time to retransmit zero window probe, thus causing the test to fail
receiving the last expected probe.

To ensure this ordering, piggyback a non-zero payload with the zero
window advertisement and let the DUT receive that, before continuing
with the test.

PiperOrigin-RevId: 361640241
This commit is contained in:
Mithun Iyer
2021-03-08 13:18:01 -08:00
committed by gVisor bot
parent cabbbb373a
commit 5a75a93202
1 changed files with 12 additions and 6 deletions
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test/packetimpact/tests/tcp_zero_window_probe_retransmit_test.go
+12 -6
View File
@@ -15,6 +15,7 @@
package tcp_zero_window_probe_retransmit_test
import (
"bytes"
"flag"
"testing"
"time"
@@ -51,18 +52,23 @@ func TestZeroWindowProbeRetransmit(t *testing.T) {
if _, err := conn.ExpectData(t, &testbench.TCP{}, samplePayload, time.Second); err != nil {
t.Fatalf("expected payload was not received: %s", err)
}
conn.Send(t, testbench.TCP{Flags: testbench.Uint8(header.TCPFlagAck | header.TCPFlagPsh)}, samplePayload)
if _, err := conn.ExpectData(t, &testbench.TCP{Flags: testbench.Uint8(header.TCPFlagAck)}, nil, time.Second); err != nil {
t.Fatalf("expected packet was not received: %s", err)
}
// Check for the dut to keep the connection alive as long as the zero window
// probes are acknowledged. Check if the zero window probes are sent at
// exponentially increasing intervals. The timeout intervals are function
// of the recorded first zero probe transmission duration.
//
// Advertize zero receive window again.
conn.Send(t, testbench.TCP{Flags: testbench.Uint8(header.TCPFlagAck), WindowSize: testbench.Uint16(0)})
// Advertize zero receive window along with a payload.
conn.Send(t, testbench.TCP{Flags: testbench.Uint8(header.TCPFlagAck | header.TCPFlagPsh), WindowSize: testbench.Uint16(0)}, samplePayload)
if _, err := conn.ExpectData(t, &testbench.TCP{Flags: testbench.Uint8(header.TCPFlagAck)}, nil, time.Second); err != nil {
t.Fatalf("expected packet was not received: %s", err)
}
// Wait for the payload to be received by the DUT, which is also an
// indication of receive of the peer window advertisement.
if got := dut.Recv(t, acceptFd, int32(len(sampleData)), 0); !bytes.Equal(got, sampleData) {
t.Fatalf("got dut.Recv(t, %d, %d, 0) = %s, want %s", acceptFd, len(sampleData), got, sampleData)
}
probeSeq := testbench.Uint32(uint32(*conn.RemoteSeqNum(t) - 1))
ackProbe := testbench.Uint32(uint32(*conn.RemoteSeqNum(t)))