Use the stack clock everywhere

Updates #5939.
Updates #6012.

RELNOTES: n/a
PiperOrigin-RevId: 375931554

7 files changed, 22 insertions, 87 deletions

diff --git a/pkg/tcpip/stack/conntrack.go b/pkg/tcpip/stack/conntrack.go
index 5720e7543..f7fbcbaa7 100644
--- a/pkg/tcpip/stack/conntrack.go
+++ b/pkg/tcpip/stack/conntrack.go
@@ -125,6 +125,8 @@ type conn struct {
 	tcb tcpconntrack.TCB
 	// lastUsed is the last time the connection saw a relevant packet, and
 	// is updated by each packet on the connection. It is protected by mu.
+	//
+	// TODO(gvisor.dev/issue/5939): do not use the ambient clock.
 	lastUsed time.Time `state:".(unixTime)"`
 }
 
diff --git a/pkg/tcpip/stack/iptables.go b/pkg/tcpip/stack/iptables.go
index 3670d5995..d2f666c09 100644
--- a/pkg/tcpip/stack/iptables.go
+++ b/pkg/tcpip/stack/iptables.go
@@ -371,6 +371,7 @@ func (it *IPTables) startReaper(interval time.Duration) {
 			select {
 			case <-it.reaperDone:
 				return
+				// TODO(gvisor.dev/issue/5939): do not use the ambient clock.
 			case <-time.After(interval):
 				bucket, interval = it.connections.reapUnused(bucket, interval)
 			}
diff --git a/pkg/tcpip/stack/neighbor_cache.go b/pkg/tcpip/stack/neighbor_cache.go
index 509f5ce5c..08857e1a9 100644
--- a/pkg/tcpip/stack/neighbor_cache.go
+++ b/pkg/tcpip/stack/neighbor_cache.go
@@ -310,7 +310,7 @@ func (n *neighborCache) handleUpperLevelConfirmation(addr tcpip.Address) {
 func (n *neighborCache) init(nic *nic, r LinkAddressResolver) {
 	*n = neighborCache{
 		nic:     nic,
-		state:   NewNUDState(nic.stack.nudConfigs, nic.stack.randomGenerator),
+		state:   NewNUDState(nic.stack.nudConfigs, nic.stack.clock, nic.stack.randomGenerator),
 		linkRes: r,
 	}
 	n.mu.Lock()
diff --git a/pkg/tcpip/stack/nud.go b/pkg/tcpip/stack/nud.go
index dac94cbe4..ca9822bca 100644
--- a/pkg/tcpip/stack/nud.go
+++ b/pkg/tcpip/stack/nud.go
@@ -316,7 +316,8 @@ func calcMaxRandomFactor(minRandomFactor float32) float32 {
 
 // NUDState stores states needed for calculating reachable time.
 type NUDState struct {
-	rng *rand.Rand
+	clock tcpip.Clock
+	rng   *rand.Rand
 
 	mu struct {
 		sync.RWMutex
@@ -337,9 +338,10 @@ type NUDState struct {
 
 // NewNUDState returns new NUDState using c as configuration and the specified
 // random number generator for use in recomputing ReachableTime.
-func NewNUDState(c NUDConfigurations, rng *rand.Rand) *NUDState {
+func NewNUDState(c NUDConfigurations, clock tcpip.Clock, rng *rand.Rand) *NUDState {
 	s := &NUDState{
-		rng: rng,
+		clock: clock,
+		rng:   rng,
 	}
 	s.mu.config = c
 	return s
@@ -367,7 +369,7 @@ func (s *NUDState) ReachableTime() time.Duration {
 	s.mu.Lock()
 	defer s.mu.Unlock()
 
-	if time.Now().After(s.mu.expiration) ||
+	if s.clock.Now().After(s.mu.expiration) ||
 		s.mu.config.BaseReachableTime != s.mu.prevBaseReachableTime ||
 		s.mu.config.MinRandomFactor != s.mu.prevMinRandomFactor ||
 		s.mu.config.MaxRandomFactor != s.mu.prevMaxRandomFactor {
@@ -416,5 +418,5 @@ func (s *NUDState) recomputeReachableTimeLocked() {
 		s.mu.reachableTime = time.Duration(reachableTime)
 	}
 
-	s.mu.expiration = time.Now().Add(2 * time.Hour)
+	s.mu.expiration = s.clock.Now().Add(2 * time.Hour)
 }
diff --git a/pkg/tcpip/stack/nud_test.go b/pkg/tcpip/stack/nud_test.go
index bfce2fe16..1aeb2f8a5 100644
--- a/pkg/tcpip/stack/nud_test.go
+++ b/pkg/tcpip/stack/nud_test.go
@@ -711,7 +711,8 @@ func TestNUDStateReachableTime(t *testing.T) {
 			rng := fakeRand{
 				num: defaultFakeRandomNum,
 			}
-			s := stack.NewNUDState(c, rand.New(&rng))
+			var clock faketime.NullClock
+			s := stack.NewNUDState(c, &clock, rand.New(&rng))
 			if got, want := s.ReachableTime(), test.want; got != want {
 				t.Errorf("got ReachableTime = %q, want = %q", got, want)
 			}
@@ -783,7 +784,8 @@ func TestNUDStateRecomputeReachableTime(t *testing.T) {
 			rng := fakeRand{
 				num: defaultFakeRandomNum,
 			}
-			s := stack.NewNUDState(c, rand.New(&rng))
+			var clock faketime.NullClock
+			s := stack.NewNUDState(c, &clock, rand.New(&rng))
 			old := s.ReachableTime()
 
 			if got, want := s.ReachableTime(), old; got != want {
diff --git a/pkg/tcpip/stack/stack_global_state.go b/pkg/tcpip/stack/stack_global_state.go
index 33824afd0..dfec4258a 100644
--- a/pkg/tcpip/stack/stack_global_state.go
+++ b/pkg/tcpip/stack/stack_global_state.go
@@ -14,78 +14,6 @@
 
 package stack
 
-import "time"
-
 // StackFromEnv is the global stack created in restore run.
 // FIXME(b/36201077)
 var StackFromEnv *Stack
-
-// saveT is invoked by stateify.
-func (t *TCPCubicState) saveT() unixTime {
-	return unixTime{t.T.Unix(), t.T.UnixNano()}
-}
-
-// loadT is invoked by stateify.
-func (t *TCPCubicState) loadT(unix unixTime) {
-	t.T = time.Unix(unix.second, unix.nano)
-}
-
-// saveXmitTime is invoked by stateify.
-func (t *TCPRACKState) saveXmitTime() unixTime {
-	return unixTime{t.XmitTime.Unix(), t.XmitTime.UnixNano()}
-}
-
-// loadXmitTime is invoked by stateify.
-func (t *TCPRACKState) loadXmitTime(unix unixTime) {
-	t.XmitTime = time.Unix(unix.second, unix.nano)
-}
-
-// saveLastSendTime is invoked by stateify.
-func (t *TCPSenderState) saveLastSendTime() unixTime {
-	return unixTime{t.LastSendTime.Unix(), t.LastSendTime.UnixNano()}
-}
-
-// loadLastSendTime is invoked by stateify.
-func (t *TCPSenderState) loadLastSendTime(unix unixTime) {
-	t.LastSendTime = time.Unix(unix.second, unix.nano)
-}
-
-// saveRTTMeasureTime is invoked by stateify.
-func (t *TCPSenderState) saveRTTMeasureTime() unixTime {
-	return unixTime{t.RTTMeasureTime.Unix(), t.RTTMeasureTime.UnixNano()}
-}
-
-// loadRTTMeasureTime is invoked by stateify.
-func (t *TCPSenderState) loadRTTMeasureTime(unix unixTime) {
-	t.RTTMeasureTime = time.Unix(unix.second, unix.nano)
-}
-
-// saveMeasureTime is invoked by stateify.
-func (r *RcvBufAutoTuneParams) saveMeasureTime() unixTime {
-	return unixTime{r.MeasureTime.Unix(), r.MeasureTime.UnixNano()}
-}
-
-// loadMeasureTime is invoked by stateify.
-func (r *RcvBufAutoTuneParams) loadMeasureTime(unix unixTime) {
-	r.MeasureTime = time.Unix(unix.second, unix.nano)
-}
-
-// saveRTTMeasureTime is invoked by stateify.
-func (r *RcvBufAutoTuneParams) saveRTTMeasureTime() unixTime {
-	return unixTime{r.RTTMeasureTime.Unix(), r.RTTMeasureTime.UnixNano()}
-}
-
-// loadRTTMeasureTime is invoked by stateify.
-func (r *RcvBufAutoTuneParams) loadRTTMeasureTime(unix unixTime) {
-	r.RTTMeasureTime = time.Unix(unix.second, unix.nano)
-}
-
-// saveSegTime is invoked by stateify.
-func (t *TCPEndpointState) saveSegTime() unixTime {
-	return unixTime{t.SegTime.Unix(), t.SegTime.UnixNano()}
-}
-
-// loadSegTime is invoked by stateify.
-func (t *TCPEndpointState) loadSegTime(unix unixTime) {
-	t.SegTime = time.Unix(unix.second, unix.nano)
-}
diff --git a/pkg/tcpip/stack/tcp.go b/pkg/tcpip/stack/tcp.go
index ddff6e2d6..e90c1a770 100644
--- a/pkg/tcpip/stack/tcp.go
+++ b/pkg/tcpip/stack/tcp.go
@@ -39,7 +39,7 @@ type TCPCubicState struct {
 	WMax float64
 
 	// T is the time when the current congestion avoidance was entered.
-	T time.Time `state:".(unixTime)"`
+	T tcpip.MonotonicTime
 
 	// TimeSinceLastCongestion denotes the time since the current
 	// congestion avoidance was entered.
@@ -78,7 +78,7 @@ type TCPCubicState struct {
 type TCPRACKState struct {
 	// XmitTime is the transmission timestamp of the most recent
 	// acknowledged segment.
-	XmitTime time.Time `state:".(unixTime)"`
+	XmitTime tcpip.MonotonicTime
 
 	// EndSequence is the ending TCP sequence number of the most recent
 	// acknowledged segment.
@@ -216,7 +216,7 @@ type TCPRTTState struct {
 // +stateify savable
 type TCPSenderState struct {
 	// LastSendTime is the timestamp at which we sent the last segment.
-	LastSendTime time.Time `state:".(unixTime)"`
+	LastSendTime tcpip.MonotonicTime
 
 	// DupAckCount is the number of Duplicate ACKs received. It is used for
 	// fast retransmit.
@@ -256,7 +256,7 @@ type TCPSenderState struct {
 	RTTMeasureSeqNum seqnum.Value
 
 	// RTTMeasureTime is the time when the RTTMeasureSeqNum was sent.
-	RTTMeasureTime time.Time `state:".(unixTime)"`
+	RTTMeasureTime tcpip.MonotonicTime
 
 	// Closed indicates that the caller has closed the endpoint for
 	// sending.
@@ -313,7 +313,7 @@ type TCPSACKInfo struct {
 type RcvBufAutoTuneParams struct {
 	// MeasureTime is the time at which the current measurement was
 	// started.
-	MeasureTime time.Time `state:".(unixTime)"`
+	MeasureTime tcpip.MonotonicTime
 
 	// CopiedBytes is the number of bytes copied to user space since this
 	// measure began.
@@ -341,7 +341,7 @@ type RcvBufAutoTuneParams struct {
 
 	// RTTMeasureTime is the absolute time at which the current RTT
 	// measurement period began.
-	RTTMeasureTime time.Time `state:".(unixTime)"`
+	RTTMeasureTime tcpip.MonotonicTime
 
 	// Disabled is true if an explicit receive buffer is set for the
 	// endpoint.
@@ -429,7 +429,7 @@ type TCPEndpointState struct {
 	ID TCPEndpointID
 
 	// SegTime denotes the absolute time when this segment was received.
-	SegTime time.Time `state:".(unixTime)"`
+	SegTime tcpip.MonotonicTime
 
 	// RcvBufState contains information about the state of the endpoint's
 	// receive socket buffer.