110 lines
4.5 KiB
Go
110 lines
4.5 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_close_wait_ack_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/pkg/tcpip/seqnum"
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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.RegisterFlags(flag.CommandLine)
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}
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func TestCloseWaitAck(t *testing.T) {
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for _, tt := range []struct {
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description string
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makeTestingTCP func(t *testing.T, conn *testbench.TCPIPv4, seqNumOffset, windowSize seqnum.Size) testbench.TCP
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seqNumOffset seqnum.Size
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expectAck bool
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}{
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{"OTW", generateOTWSeqSegment, 0, false},
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{"OTW", generateOTWSeqSegment, 1, true},
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{"OTW", generateOTWSeqSegment, 2, true},
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{"ACK", generateUnaccACKSegment, 0, false},
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{"ACK", generateUnaccACKSegment, 1, true},
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{"ACK", generateUnaccACKSegment, 2, true},
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} {
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t.Run(fmt.Sprintf("%s%d", tt.description, tt.seqNumOffset), func(t *testing.T) {
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dut := testbench.NewDUT(t)
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defer dut.TearDown()
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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 := testbench.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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// Send a FIN to DUT to intiate the active close
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conn.Send(t, testbench.TCP{Flags: testbench.Uint8(header.TCPFlagAck | header.TCPFlagFin)})
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gotTCP, err := conn.Expect(t, testbench.TCP{Flags: testbench.Uint8(header.TCPFlagAck)}, time.Second)
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if err != nil {
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t.Fatalf("expected an ACK for our fin and DUT should enter CLOSE_WAIT: %s", err)
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}
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windowSize := seqnum.Size(*gotTCP.WindowSize)
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// Send a segment with OTW Seq / unacc ACK and expect an ACK back
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conn.Send(t, tt.makeTestingTCP(t, &conn, tt.seqNumOffset, windowSize), &testbench.Payload{Bytes: []byte("Sample Data")})
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gotAck, err := conn.Expect(t, testbench.TCP{Flags: testbench.Uint8(header.TCPFlagAck)}, time.Second)
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if tt.expectAck && err != nil {
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t.Fatalf("expected an ack but got none: %s", err)
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}
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if !tt.expectAck && gotAck != nil {
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t.Fatalf("expected no ack but got one: %s", gotAck)
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}
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// Now let's verify DUT is indeed in CLOSE_WAIT
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dut.Close(t, acceptFd)
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if _, err := conn.Expect(t, testbench.TCP{Flags: testbench.Uint8(header.TCPFlagAck | header.TCPFlagFin)}, time.Second); err != nil {
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t.Fatalf("expected DUT to send a FIN: %s", err)
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}
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// Ack the FIN from DUT
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conn.Send(t, testbench.TCP{Flags: testbench.Uint8(header.TCPFlagAck)})
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// Send some extra data to DUT
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conn.Send(t, testbench.TCP{Flags: testbench.Uint8(header.TCPFlagAck)}, &testbench.Payload{Bytes: []byte("Sample Data")})
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if _, err := conn.Expect(t, testbench.TCP{Flags: testbench.Uint8(header.TCPFlagRst)}, time.Second); err != nil {
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t.Fatalf("expected DUT to send an RST: %s", err)
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}
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})
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}
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}
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// generateOTWSeqSegment generates an segment with
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// seqnum = RCV.NXT + RCV.WND + seqNumOffset, the generated segment is only
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// acceptable when seqNumOffset is 0, otherwise an ACK is expected from the
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// receiver.
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func generateOTWSeqSegment(t *testing.T, conn *testbench.TCPIPv4, seqNumOffset seqnum.Size, windowSize seqnum.Size) testbench.TCP {
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lastAcceptable := conn.LocalSeqNum(t).Add(windowSize)
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otwSeq := uint32(lastAcceptable.Add(seqNumOffset))
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return testbench.TCP{SeqNum: testbench.Uint32(otwSeq), Flags: testbench.Uint8(header.TCPFlagAck)}
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}
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// generateUnaccACKSegment generates an segment with
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// acknum = SND.NXT + seqNumOffset, the generated segment is only acceptable
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// when seqNumOffset is 0, otherwise an ACK is expected from the receiver.
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func generateUnaccACKSegment(t *testing.T, conn *testbench.TCPIPv4, seqNumOffset seqnum.Size, windowSize seqnum.Size) testbench.TCP {
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lastAcceptable := conn.RemoteSeqNum(t)
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unaccAck := uint32(lastAcceptable.Add(seqNumOffset))
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return testbench.TCP{AckNum: testbench.Uint32(unaccAck), Flags: testbench.Uint8(header.TCPFlagAck)}
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}
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