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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"
"gvisor.dev/gvisor/pkg/tcpip/faketime"
"gvisor.dev/gvisor/pkg/tcpip/header"
)
// TestNATedConnectionReap tests that NATed connections are properly reaped.
func TestNATedConnectionReap(t *testing.T) {
// Note that the network protocol used for this test doesn't matter as this
// test focuses on reaping, not anything related to a specific network
// protocol.
const (
nattedDstPort = 1
srcPort = 2
dstPort = 3
nattedDstAddr = tcpip.Address("\x0a\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x01")
srcAddr = tcpip.Address("\x0b\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x02")
dstAddr = tcpip.Address("\x0c\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x03")
)
clock := faketime.NewManualClock()
iptables := DefaultTables(0 /* seed */, clock)
table := Table{
Rules: []Rule{
// Prerouting
{
Target: &DNATTarget{NetworkProtocol: header.IPv6ProtocolNumber, Addr: nattedDstAddr, Port: nattedDstPort},
},
{
Target: &AcceptTarget{},
},
// Input
{
Target: &AcceptTarget{},
},
// Forward
{
Target: &AcceptTarget{},
},
// Output
{
Target: &AcceptTarget{},
},
// Postrouting
{
Target: &AcceptTarget{},
},
},
BuiltinChains: [NumHooks]int{
Prerouting: 0,
Input: 2,
Forward: 3,
Output: 4,
Postrouting: 5,
},
}
if err := iptables.ReplaceTable(NATID, table, true /* ipv6 */); err != nil {
t.Fatalf("ipt.ReplaceTable(%d, _, true): %s", NATID, err)
}
// Stop the reaper if it is running so we can reap manually as it is started
// on the first change to IPTables.
iptables.reaperDone <- struct{}{}
pkt := NewPacketBuffer(PacketBufferOptions{
ReserveHeaderBytes: header.IPv6MinimumSize + header.UDPMinimumSize,
})
udp := header.UDP(pkt.TransportHeader().Push(header.UDPMinimumSize))
udp.SetSourcePort(srcPort)
udp.SetDestinationPort(dstPort)
udp.SetChecksum(0)
udp.SetChecksum(^udp.CalculateChecksum(header.PseudoHeaderChecksum(
header.UDPProtocolNumber,
srcAddr,
dstAddr,
uint16(len(udp)),
)))
pkt.TransportProtocolNumber = header.UDPProtocolNumber
ip := header.IPv6(pkt.NetworkHeader().Push(header.IPv6MinimumSize))
ip.Encode(&header.IPv6Fields{
PayloadLength: uint16(len(udp)),
TransportProtocol: header.UDPProtocolNumber,
HopLimit: 64,
SrcAddr: srcAddr,
DstAddr: dstAddr,
})
pkt.NetworkProtocolNumber = header.IPv6ProtocolNumber
originalTID, _, ok := getTupleID(pkt)
if !ok {
t.Fatal("failed to get original tuple ID")
}
if !iptables.CheckPrerouting(pkt, nil /* addressEP */, "" /* inNicName */) {
t.Fatal("got ipt.CheckPrerouting(...) = false, want = true")
}
if !iptables.CheckInput(pkt, "" /* inNicName */) {
t.Fatal("got ipt.CheckInput(...) = false, want = true")
}
invertedReplyTID, _, ok := getTupleID(pkt)
if !ok {
t.Fatal("failed to get NATed packet's tuple ID")
}
if invertedReplyTID == originalTID {
t.Fatalf("NAT not performed; got invertedReplyTID = %#v", invertedReplyTID)
}
replyTID := invertedReplyTID.reply()
originalBktID := iptables.connections.bucket(originalTID)
replyBktID := iptables.connections.bucket(replyTID)
// This test depends on the original and reply tuples mapping to different
// buckets.
if originalBktID == replyBktID {
t.Fatalf("expected bucket IDs to be different; got = %d", originalBktID)
}
lowerBktID := originalBktID
if lowerBktID > replyBktID {
lowerBktID = replyBktID
}
runReaper := func() {
// Reaping the bucket with the lower ID should reap both tuples of the
// connection if it has timed out.
//
// We will manually pick the next start bucket ID and don't use the
// interval so we ignore the return values.
_, _ = iptables.connections.reapUnused(lowerBktID, 0 /* prevInterval */)
}
iptables.connections.mu.RLock()
buckets := iptables.connections.buckets
iptables.connections.mu.RUnlock()
originalBkt := &buckets[originalBktID]
replyBkt := &buckets[replyBktID]
// Run the reaper and make sure the tuples were not reaped.
reapAndCheckForConnections := func() {
t.Helper()
runReaper()
now := clock.NowMonotonic()
if originalTuple := originalBkt.connForTID(originalTID, now); originalTuple == nil {
t.Error("expected to get original tuple")
}
if replyTuple := replyBkt.connForTID(replyTID, now); replyTuple == nil {
t.Error("expected to get reply tuple")
}
if t.Failed() {
t.FailNow()
}
}
// Connection was just added and no time has passed - it should not be reaped.
reapAndCheckForConnections()
// Time must advance past the unestablished timeout for a connection to be
// reaped.
clock.Advance(unestablishedTimeout)
reapAndCheckForConnections()
// Connection should now be reaped.
clock.Advance(1)
runReaper()
now := clock.NowMonotonic()
if originalTuple := originalBkt.connForTID(originalTID, now); originalTuple != nil {
t.Errorf("got originalBkt.connForTID(%#v, %#v) = %#v, want = nil", originalTID, now, originalTuple)
}
if replyTuple := replyBkt.connForTID(replyTID, now); replyTuple != nil {
t.Errorf("got replyBkt.connForTID(%#v, %#v) = %#v, want = nil", replyTID, now, replyTuple)
}
// Make sure we don't have stale tuples just lying around.
//
// We manually check the buckets as connForTID will skip over tuples that
// have timed out.
checkNoTupleInBucket := func(bkt *bucket, tid tupleID, reply bool) {
t.Helper()
bkt.mu.RLock()
defer bkt.mu.RUnlock()
for tuple := bkt.tuples.Front(); tuple != nil; tuple = tuple.Next() {
if tuple.id() == originalTID {
t.Errorf("unexpectedly found tuple with ID = %#v; reply = %t", tid, reply)
}
}
}
checkNoTupleInBucket(originalBkt, originalTID, false /* reply */)
checkNoTupleInBucket(replyBkt, replyTID, true /* reply */)
}
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