126 lines
4.7 KiB
Go
126 lines
4.7 KiB
Go
// Copyright 2020 The gVisor Authors.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package tcp_zero_receive_window_test
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import (
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"flag"
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"fmt"
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"testing"
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"time"
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"golang.org/x/sys/unix"
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"gvisor.dev/gvisor/pkg/tcpip/header"
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"gvisor.dev/gvisor/test/packetimpact/testbench"
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)
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func init() {
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testbench.Initialize(flag.CommandLine)
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}
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// TestZeroReceiveWindow tests if the DUT sends a zero receive window eventually.
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func TestZeroReceiveWindow(t *testing.T) {
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for _, payloadLen := range []int{64, 512, 1024} {
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t.Run(fmt.Sprintf("TestZeroReceiveWindow_with_%dbytes_payload", payloadLen), func(t *testing.T) {
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dut := testbench.NewDUT(t)
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listenFd, remotePort := dut.CreateListener(t, unix.SOCK_STREAM, unix.IPPROTO_TCP, 1)
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defer dut.Close(t, listenFd)
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conn := dut.Net.NewTCPIPv4(t, testbench.TCP{DstPort: &remotePort}, testbench.TCP{SrcPort: &remotePort})
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defer conn.Close(t)
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conn.Connect(t)
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acceptFd, _ := dut.Accept(t, listenFd)
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defer dut.Close(t, acceptFd)
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dut.SetSockOptInt(t, acceptFd, unix.IPPROTO_TCP, unix.TCP_NODELAY, 1)
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samplePayload := &testbench.Payload{Bytes: testbench.GenerateRandomPayload(t, payloadLen)}
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// Expect the DUT to eventually advertise zero receive window.
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// The test would timeout otherwise.
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for readOnce := false; ; {
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conn.Send(t, testbench.TCP{Flags: testbench.TCPFlags(header.TCPFlagAck | header.TCPFlagPsh)}, samplePayload)
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gotTCP, err := conn.Expect(t, testbench.TCP{Flags: testbench.TCPFlags(header.TCPFlagAck)}, time.Second)
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if err != nil {
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t.Fatalf("expected packet was not received: %s", err)
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}
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// Read once to trigger the subsequent window update from the
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// DUT to grow the right edge of the receive window from what
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// was advertised in the SYN-ACK. This ensures that we test
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// for the full default buffer size (1MB on gVisor at the time
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// of writing this comment), thus testing for cases when the
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// scaled receive window size ends up > 65535 (0xffff).
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if !readOnce {
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if got := dut.Recv(t, acceptFd, int32(payloadLen), 0); len(got) != payloadLen {
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t.Fatalf("got dut.Recv(t, %d, %d, 0) = %d, want %d", acceptFd, payloadLen, len(got), payloadLen)
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}
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readOnce = true
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}
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windowSize := *gotTCP.WindowSize
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t.Logf("got window size = %d", windowSize)
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if windowSize == 0 {
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break
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}
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}
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})
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}
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}
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// TestNonZeroReceiveWindow tests for the DUT to never send a zero receive
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// window when the data is being read from the socket buffer.
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func TestNonZeroReceiveWindow(t *testing.T) {
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for _, payloadLen := range []int{64, 512, 1024} {
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t.Run(fmt.Sprintf("TestZeroReceiveWindow_with_%dbytes_payload", payloadLen), func(t *testing.T) {
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dut := testbench.NewDUT(t)
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listenFd, remotePort := dut.CreateListener(t, unix.SOCK_STREAM, unix.IPPROTO_TCP, 1)
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defer dut.Close(t, listenFd)
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conn := dut.Net.NewTCPIPv4(t, testbench.TCP{DstPort: &remotePort}, testbench.TCP{SrcPort: &remotePort})
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defer conn.Close(t)
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conn.Connect(t)
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acceptFd, _ := dut.Accept(t, listenFd)
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defer dut.Close(t, acceptFd)
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dut.SetSockOptInt(t, acceptFd, unix.IPPROTO_TCP, unix.TCP_NODELAY, 1)
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samplePayload := &testbench.Payload{Bytes: testbench.GenerateRandomPayload(t, payloadLen)}
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var rcvWindow uint16
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initRcv := false
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// This loop keeps a running rcvWindow value from the initial ACK for the data
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// we sent. Once we have received ACKs with non-zero receive windows, we break
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// the loop.
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for {
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conn.Send(t, testbench.TCP{Flags: testbench.TCPFlags(header.TCPFlagAck | header.TCPFlagPsh)}, samplePayload)
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gotTCP, err := conn.Expect(t, testbench.TCP{Flags: testbench.TCPFlags(header.TCPFlagAck)}, time.Second)
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if err != nil {
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t.Fatalf("expected packet was not received: %s", err)
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}
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if got := dut.Recv(t, acceptFd, int32(payloadLen), 0); len(got) != payloadLen {
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t.Fatalf("got dut.Recv(t, %d, %d, 0) = %d, want %d", acceptFd, payloadLen, len(got), payloadLen)
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}
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if *gotTCP.WindowSize == 0 {
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t.Fatalf("expected non-zero receive window.")
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}
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if !initRcv {
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rcvWindow = uint16(*gotTCP.WindowSize)
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initRcv = true
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}
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if rcvWindow <= uint16(payloadLen) {
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break
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}
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rcvWindow -= uint16(payloadLen)
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}
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})
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}
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}
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