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// Copyright 2021 The gVisor Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package stack
import (
"testing"
"gvisor.dev/gvisor/pkg/tcpip/faketime"
"gvisor.dev/gvisor/pkg/tcpip/header"
"gvisor.dev/gvisor/pkg/tcpip/testutil"
)
func TestReap(t *testing.T) {
// Initialize conntrack.
clock := faketime.NewManualClock()
ct := ConnTrack{
clock: clock,
}
ct.init()
ct.checkNumTuples(t, 0)
// Simulate sending a SYN. This will get the connection into conntrack, but
// the connection won't be considered established. Thus the timeout for
// reaping is unestablishedTimeout.
pkt1 := genTCPPacket()
pkt1.tuple = ct.getConnOrMaybeInsertNoop(pkt1)
// We set rt.routeInfo.Loop to avoid a panic when handlePacket calls
// rt.RequiresTXTransportChecksum.
var rt Route
rt.routeInfo.Loop = PacketLoop
if pkt1.tuple.conn.handlePacket(pkt1, Output, &rt) {
t.Fatal("handlePacket() shouldn't perform any NAT")
}
ct.checkNumTuples(t, 1)
// Travel a little into the future and send the same SYN. This should update
// lastUsed, but per #6748 didn't.
clock.Advance(unestablishedTimeout / 2)
pkt2 := genTCPPacket()
pkt2.tuple = ct.getConnOrMaybeInsertNoop(pkt2)
if pkt2.tuple.conn.handlePacket(pkt2, Output, &rt) {
t.Fatal("handlePacket() shouldn't perform any NAT")
}
ct.checkNumTuples(t, 1)
// Travel farther into the future - enough that failing to update lastUsed
// would cause a reaping - and reap the whole table. Make sure the connection
// hasn't been reaped.
clock.Advance(unestablishedTimeout * 3 / 4)
ct.reapEverything()
ct.checkNumTuples(t, 1)
// Travel past unestablishedTimeout to confirm the tuple is gone.
clock.Advance(unestablishedTimeout / 2)
ct.reapEverything()
ct.checkNumTuples(t, 0)
}
// genTCPPacket returns an initialized IPv4 TCP packet.
func genTCPPacket() *PacketBuffer {
const packetLen = header.IPv4MinimumSize + header.TCPMinimumSize
pkt := NewPacketBuffer(PacketBufferOptions{
ReserveHeaderBytes: packetLen,
})
pkt.NetworkProtocolNumber = header.IPv4ProtocolNumber
pkt.TransportProtocolNumber = header.TCPProtocolNumber
tcpHdr := header.TCP(pkt.TransportHeader().Push(header.TCPMinimumSize))
tcpHdr.Encode(&header.TCPFields{
SrcPort: 5555,
DstPort: 6666,
SeqNum: 7777,
AckNum: 8888,
DataOffset: header.TCPMinimumSize,
Flags: header.TCPFlagSyn,
WindowSize: 50000,
Checksum: 0, // Conntrack doesn't verify the checksum.
})
ipHdr := header.IPv4(pkt.NetworkHeader().Push(header.IPv4MinimumSize))
ipHdr.Encode(&header.IPv4Fields{
TotalLength: packetLen,
Protocol: uint8(header.TCPProtocolNumber),
SrcAddr: testutil.MustParse4("1.0.0.1"),
DstAddr: testutil.MustParse4("1.0.0.2"),
Checksum: 0, // Conntrack doesn't verify the checksum.
})
return pkt
}
// checkNumTuples checks that there are exactly want tuples tracked by
// conntrack.
func (ct *ConnTrack) checkNumTuples(t *testing.T, want int) {
t.Helper()
ct.mu.RLock()
defer ct.mu.RUnlock()
var total int
for idx := range ct.buckets {
ct.buckets[idx].mu.RLock()
total += ct.buckets[idx].tuples.Len()
ct.buckets[idx].mu.RUnlock()
}
if total != want {
t.Fatalf("checkNumTuples: got %d, wanted %d", total, want)
}
}
func (ct *ConnTrack) reapEverything() {
var bucket int
for {
newBucket, _ := ct.reapUnused(bucket, 0 /* ignored */)
// We started reaping at bucket 0. If the next bucket isn't after our
// current bucket, we've gone through them all.
if newBucket <= bucket {
break
}
bucket = newBucket
}
}
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