From 5a75a932029fb5de712b2ae4ec62be6bfe6ce6f8 Mon Sep 17 00:00:00 2001 From: Mithun Iyer Date: Mon, 8 Mar 2021 13:15:51 -0800 Subject: Avoid a race with test peer advert and DUT send 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 --- .../tests/tcp_zero_window_probe_retransmit_test.go | 18 ++++++++++++------ 1 file changed, 12 insertions(+), 6 deletions(-) (limited to 'test/packetimpact/tests') diff --git a/test/packetimpact/tests/tcp_zero_window_probe_retransmit_test.go b/test/packetimpact/tests/tcp_zero_window_probe_retransmit_test.go index d094c10eb..413cfa236 100644 --- a/test/packetimpact/tests/tcp_zero_window_probe_retransmit_test.go +++ b/test/packetimpact/tests/tcp_zero_window_probe_retransmit_test.go @@ -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))) -- cgit v1.2.3