94 lines
3.5 KiB
Go
94 lines
3.5 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_outside_the_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/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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// TestTCPOutsideTheWindows tests the behavior of the DUT when packets arrive
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// that are inside or outside the TCP window. Packets that are outside the
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// window should force an extra ACK, as described in RFC793 page 69:
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// https://tools.ietf.org/html/rfc793#page-69
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func TestTCPOutsideTheWindow(t *testing.T) {
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for _, tt := range []struct {
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description string
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tcpFlags uint8
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payload []testbench.Layer
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seqNumOffset seqnum.Size
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expectACK bool
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}{
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{"SYN", header.TCPFlagSyn, nil, 0, true},
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{"SYNACK", header.TCPFlagSyn | header.TCPFlagAck, nil, 0, true},
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{"ACK", header.TCPFlagAck, nil, 0, false},
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{"FIN", header.TCPFlagFin, nil, 0, false},
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{"Data", header.TCPFlagAck, []testbench.Layer{&testbench.Payload{Bytes: []byte("abc123")}}, 0, true},
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{"SYN", header.TCPFlagSyn, nil, 1, true},
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{"SYNACK", header.TCPFlagSyn | header.TCPFlagAck, nil, 1, true},
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{"ACK", header.TCPFlagAck, nil, 1, true},
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{"FIN", header.TCPFlagFin, nil, 1, false},
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{"Data", header.TCPFlagAck, []testbench.Layer{&testbench.Payload{Bytes: []byte("abc123")}}, 1, true},
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{"SYN", header.TCPFlagSyn, nil, 2, true},
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{"SYNACK", header.TCPFlagSyn | header.TCPFlagAck, nil, 2, true},
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{"ACK", header.TCPFlagAck, nil, 2, true},
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{"FIN", header.TCPFlagFin, nil, 2, false},
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{"Data", header.TCPFlagAck, []testbench.Layer{&testbench.Payload{Bytes: []byte("abc123")}}, 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(unix.SOCK_STREAM, unix.IPPROTO_TCP, 1)
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defer dut.Close(listenFD)
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conn := testbench.NewTCPIPv4(t, testbench.TCP{DstPort: &remotePort}, testbench.TCP{SrcPort: &remotePort})
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defer conn.Close()
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conn.Connect()
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acceptFD, _ := dut.Accept(listenFD)
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defer dut.Close(acceptFD)
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windowSize := seqnum.Size(*conn.SynAck().WindowSize) + tt.seqNumOffset
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conn.Drain()
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// Ignore whatever incrementing that this out-of-order packet might cause
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// to the AckNum.
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localSeqNum := testbench.Uint32(uint32(*conn.LocalSeqNum()))
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conn.Send(testbench.TCP{
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Flags: testbench.Uint8(tt.tcpFlags),
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SeqNum: testbench.Uint32(uint32(conn.LocalSeqNum().Add(windowSize))),
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}, tt.payload...)
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timeout := 3 * time.Second
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gotACK, err := conn.Expect(testbench.TCP{Flags: testbench.Uint8(header.TCPFlagAck), AckNum: localSeqNum}, timeout)
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if tt.expectACK && err != nil {
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t.Fatalf("expected an ACK packet within %s but got none: %s", timeout, err)
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}
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if !tt.expectACK && gotACK != nil {
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t.Fatalf("expected no ACK packet within %s but got one: %s", timeout, gotACK)
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}
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})
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}
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}
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