Use fake clocks in all tests

...except TCP tests and NDP tests that mutate globals. These will be
undertaken later.

Updates #5940.

PiperOrigin-RevId: 376145608

pkg/tcpip/checker/checker.go

@@ -50,7 +50,7 @@ func IPv4(t *testing.T, b []byte, checkers ...NetworkChecker) {
 	ipv4 := header.IPv4(b)
 
 	if !ipv4.IsValid(len(b)) {
-		t.Error("Not a valid IPv4 packet")
+		t.Fatalf("Not a valid IPv4 packet: %x", ipv4)
 	}
 
 	if !ipv4.IsChecksumValid() {
@@ -72,7 +72,7 @@ func IPv6(t *testing.T, b []byte, checkers ...NetworkChecker) {
 
 	ipv6 := header.IPv6(b)
 	if !ipv6.IsValid(len(b)) {
-		t.Error("Not a valid IPv6 packet")
+		t.Fatalf("Not a valid IPv6 packet: %x", ipv6)
 	}
 
 	for _, f := range checkers {

pkg/tcpip/network/arp/BUILD

@@ -28,13 +28,13 @@ go_test(
         ":arp",
         "//pkg/tcpip",
         "//pkg/tcpip/buffer",
+        "//pkg/tcpip/faketime",
         "//pkg/tcpip/header",
         "//pkg/tcpip/link/channel",
         "//pkg/tcpip/link/sniffer",
         "//pkg/tcpip/network/ipv4",
         "//pkg/tcpip/stack",
         "//pkg/tcpip/testutil",
-        "//pkg/tcpip/transport/icmp",
         "@com_github_google_go_cmp//cmp:go_default_library",
         "@com_github_google_go_cmp//cmp/cmpopts:go_default_library",
     ],

pkg/tcpip/network/arp/arp_test.go

@@ -15,15 +15,14 @@
 package arp_test
 
 import (
-	"context"
 	"fmt"
 	"testing"
-	"time"
 
 	"github.com/google/go-cmp/cmp"
 	"github.com/google/go-cmp/cmp/cmpopts"
 	"gvisor.dev/gvisor/pkg/tcpip"
 	"gvisor.dev/gvisor/pkg/tcpip/buffer"
+	"gvisor.dev/gvisor/pkg/tcpip/faketime"
 	"gvisor.dev/gvisor/pkg/tcpip/header"
 	"gvisor.dev/gvisor/pkg/tcpip/link/channel"
 	"gvisor.dev/gvisor/pkg/tcpip/link/sniffer"
@@ -31,7 +30,6 @@ import (
 	"gvisor.dev/gvisor/pkg/tcpip/network/ipv4"
 	"gvisor.dev/gvisor/pkg/tcpip/stack"
 	"gvisor.dev/gvisor/pkg/tcpip/testutil"
-	"gvisor.dev/gvisor/pkg/tcpip/transport/icmp"
 )
 
 const (
@@ -39,15 +37,6 @@ const (
 
 	stackLinkAddr  = tcpip.LinkAddress("\x0a\x0a\x0b\x0b\x0c\x0c")
 	remoteLinkAddr = tcpip.LinkAddress("\x01\x02\x03\x04\x05\x06")
-
-	defaultChannelSize = 1
-	defaultMTU         = 65536
-
-	// eventChanSize defines the size of event channels used by the neighbor
-	// cache's event dispatcher. The size chosen here needs to be sufficient to
-	// queue all the events received during tests before consumption.
-	// If eventChanSize is too small, the tests may deadlock.
-	eventChanSize = 32
 )
 
 var (
@@ -123,24 +112,6 @@ func (d *arpDispatcher) OnNeighborRemoved(nicID tcpip.NICID, entry stack.Neighbo
 	d.C <- e
 }
 
-func (d *arpDispatcher) waitForEvent(ctx context.Context, want eventInfo) error {
-	select {
-	case got := <-d.C:
-		if diff := cmp.Diff(want, got, cmp.AllowUnexported(got), cmpopts.IgnoreFields(stack.NeighborEntry{}, "UpdatedAt")); diff != "" {
-			return fmt.Errorf("got invalid event (-want +got):\n%s", diff)
-		}
-	case <-ctx.Done():
-		return fmt.Errorf("%s for %s", ctx.Err(), want)
-	}
-	return nil
-}
-
-func (d *arpDispatcher) waitForEventWithTimeout(want eventInfo, timeout time.Duration) error {
-	ctx, cancel := context.WithTimeout(context.Background(), timeout)
-	defer cancel()
-	return d.waitForEvent(ctx, want)
-}
-
 func (d *arpDispatcher) nextEvent() (eventInfo, bool) {
 	select {
 	case event := <-d.C:
@@ -153,55 +124,45 @@ func (d *arpDispatcher) nextEvent() (eventInfo, bool) {
 type testContext struct {
 	s       *stack.Stack
 	linkEP  *channel.Endpoint
-	nudDisp *arpDispatcher
+	nudDisp arpDispatcher
 }
 
-func newTestContext(t *testing.T) *testContext {
-	c := stack.DefaultNUDConfigurations()
-	// Transition from Reachable to Stale almost immediately to test if receiving
-	// probes refreshes positive reachability.
-	c.BaseReachableTime = time.Microsecond
+func makeTestContext(t *testing.T, eventDepth int, packetDepth int) testContext {
+	t.Helper()
 
-	d := arpDispatcher{
-		// Create an event channel large enough so the neighbor cache doesn't block
-		// while dispatching events. Blocking could interfere with the timing of
-		// NUD transitions.
-		C: make(chan eventInfo, eventChanSize),
+	tc := testContext{
+		nudDisp: arpDispatcher{
+			C: make(chan eventInfo, eventDepth),
+		},
 	}
 
-	s := stack.New(stack.Options{
-		NetworkProtocols:   []stack.NetworkProtocolFactory{ipv4.NewProtocol, arp.NewProtocol},
-		TransportProtocols: []stack.TransportProtocolFactory{icmp.NewProtocol4},
-		NUDConfigs:         c,
-		NUDDisp:            &d,
+	tc.s = stack.New(stack.Options{
+		NetworkProtocols: []stack.NetworkProtocolFactory{ipv4.NewProtocol, arp.NewProtocol},
+		NUDDisp:          &tc.nudDisp,
+		Clock:            &faketime.NullClock{},
 	})
 
-	ep := channel.New(defaultChannelSize, defaultMTU, stackLinkAddr)
-	ep.LinkEPCapabilities |= stack.CapabilityResolutionRequired
-
-	wep := stack.LinkEndpoint(ep)
+	tc.linkEP = channel.New(packetDepth, header.IPv4MinimumMTU, stackLinkAddr)
+	tc.linkEP.LinkEPCapabilities |= stack.CapabilityResolutionRequired
 
+	wep := stack.LinkEndpoint(tc.linkEP)
 	if testing.Verbose() {
-		wep = sniffer.New(ep)
+		wep = sniffer.New(wep)
 	}
-	if err := s.CreateNIC(nicID, wep); err != nil {
-		t.Fatalf("CreateNIC failed: %v", err)
+	if err := tc.s.CreateNIC(nicID, wep); err != nil {
+		t.Fatalf("CreateNIC failed: %s", err)
 	}
 
-	if err := s.AddAddress(nicID, ipv4.ProtocolNumber, stackAddr); err != nil {
-		t.Fatalf("AddAddress for ipv4 failed: %v", err)
+	if err := tc.s.AddAddress(nicID, ipv4.ProtocolNumber, stackAddr); err != nil {
+		t.Fatalf("AddAddress for ipv4 failed: %s", err)
 	}
 
-	s.SetRouteTable([]tcpip.Route{{
+	tc.s.SetRouteTable([]tcpip.Route{{
 		Destination: header.IPv4EmptySubnet,
 		NIC:         nicID,
 	}})
 
-	return &testContext{
-		s:       s,
-		linkEP:  ep,
-		nudDisp: &d,
-	}
+	return tc
 }
 
 func (c *testContext) cleanup() {
@@ -209,7 +170,7 @@ func (c *testContext) cleanup() {
 }
 
 func TestMalformedPacket(t *testing.T) {
-	c := newTestContext(t)
+	c := makeTestContext(t, 0, 0)
 	defer c.cleanup()
 
 	v := make(buffer.View, header.ARPSize)
@@ -228,7 +189,7 @@ func TestMalformedPacket(t *testing.T) {
 }
 
 func TestDisabledEndpoint(t *testing.T) {
-	c := newTestContext(t)
+	c := makeTestContext(t, 0, 0)
 	defer c.cleanup()
 
 	ep, err := c.s.GetNetworkEndpoint(nicID, header.ARPProtocolNumber)
@@ -253,7 +214,7 @@ func TestDisabledEndpoint(t *testing.T) {
 }
 
 func TestDirectReply(t *testing.T) {
-	c := newTestContext(t)
+	c := makeTestContext(t, 0, 0)
 	defer c.cleanup()
 
 	const senderMAC = "\x01\x02\x03\x04\x05\x06"
@@ -284,7 +245,7 @@ func TestDirectReply(t *testing.T) {
 }
 
 func TestDirectRequest(t *testing.T) {
-	c := newTestContext(t)
+	c := makeTestContext(t, 1, 1)
 	defer c.cleanup()
 
 	tests := []struct {
@@ -391,17 +352,21 @@ func TestDirectRequest(t *testing.T) {
 			}
 
 			// Verify the sender was saved in the neighbor cache.
-			wantEvent := eventInfo{
-				eventType: entryAdded,
-				nicID:     nicID,
-				entry: stack.NeighborEntry{
-					Addr:     test.senderAddr,
-					LinkAddr: test.senderLinkAddr,
-					State:    stack.Stale,
-				},
-			}
-			if err := c.nudDisp.waitForEventWithTimeout(wantEvent, time.Second); err != nil {
-				t.Fatal(err)
+			if got, ok := c.nudDisp.nextEvent(); ok {
+				want := eventInfo{
+					eventType: entryAdded,
+					nicID:     nicID,
+					entry: stack.NeighborEntry{
+						Addr:     test.senderAddr,
+						LinkAddr: test.senderLinkAddr,
+						State:    stack.Stale,
+					},
+				}
+				if diff := cmp.Diff(want, got, cmp.AllowUnexported(eventInfo{}), cmpopts.IgnoreFields(stack.NeighborEntry{}, "UpdatedAt")); diff != "" {
+					t.Errorf("got invalid event (-want +got):\n%s", diff)
+				}
+			} else {
+				t.Fatal("event didn't arrive")
 			}
 
 			neighbors, err := c.s.Neighbors(nicID, ipv4.ProtocolNumber)
@@ -589,7 +554,7 @@ func TestLinkAddressRequest(t *testing.T) {
 			s := stack.New(stack.Options{
 				NetworkProtocols: []stack.NetworkProtocolFactory{arp.NewProtocol, ipv4.NewProtocol},
 			})
-			linkEP := channel.New(defaultChannelSize, defaultMTU, stackLinkAddr)
+			linkEP := channel.New(1, header.IPv4MinimumMTU, stackLinkAddr)
 			if err := s.CreateNIC(nicID, &testLinkEndpoint{LinkEndpoint: linkEP, writeErr: test.linkErr}); err != nil {
 				t.Fatalf("s.CreateNIC(%d, _): %s", nicID, err)
 			}
@@ -663,15 +628,16 @@ func TestLinkAddressRequest(t *testing.T) {
 }
 
 func TestDADARPRequestPacket(t *testing.T) {
+	clock := faketime.NewManualClock()
 	s := stack.New(stack.Options{
 		NetworkProtocols: []stack.NetworkProtocolFactory{arp.NewProtocolWithOptions(arp.Options{
 			DADConfigs: stack.DADConfigurations{
 				DupAddrDetectTransmits: 1,
-				RetransmitTimer:        time.Second,
 			},
 		}), ipv4.NewProtocol},
+		Clock: clock,
 	})
-	e := channel.New(1, defaultMTU, stackLinkAddr)
+	e := channel.New(1, header.IPv4MinimumMTU, stackLinkAddr)
 	if err := s.CreateNIC(nicID, e); err != nil {
 		t.Fatalf("s.CreateNIC(%d, _): %s", nicID, err)
 	}
@@ -682,7 +648,8 @@ func TestDADARPRequestPacket(t *testing.T) {
 		t.Fatalf("got s.CheckDuplicateAddress(%d, %d, %s, _) = %d, want = %d", nicID, header.IPv4ProtocolNumber, remoteAddr, res, stack.DADStarting)
 	}
 
-	pkt, ok := e.ReadContext(context.Background())
+	clock.RunImmediatelyScheduledJobs()
+	pkt, ok := e.Read()
 	if !ok {
 		t.Fatal("expected to send an ARP request")
 	}

pkg/tcpip/network/ipv4/ipv4_test.go

@@ -16,7 +16,6 @@ package ipv4_test
 
 import (
 	"bytes"
-	"context"
 	"encoding/hex"
 	"fmt"
 	"io/ioutil"
@@ -3086,7 +3085,7 @@ func TestPacketQueing(t *testing.T) {
 				}))
 			},
 			checkResp: func(t *testing.T, e *channel.Endpoint) {
-				p, ok := e.ReadContext(context.Background())
+				p, ok := e.Read()
 				if !ok {
 					t.Fatalf("timed out waiting for packet")
 				}
@@ -3129,7 +3128,7 @@ func TestPacketQueing(t *testing.T) {
 				}))
 			},
 			checkResp: func(t *testing.T, e *channel.Endpoint) {
-				p, ok := e.ReadContext(context.Background())
+				p, ok := e.Read()
 				if !ok {
 					t.Fatalf("timed out waiting for packet")
 				}
@@ -3153,9 +3152,11 @@ func TestPacketQueing(t *testing.T) {
 		t.Run(test.name, func(t *testing.T) {
 			e := channel.New(1, defaultMTU, host1NICLinkAddr)
 			e.LinkEPCapabilities |= stack.CapabilityResolutionRequired
+			clock := faketime.NewManualClock()
 			s := stack.New(stack.Options{
 				NetworkProtocols:   []stack.NetworkProtocolFactory{arp.NewProtocol, ipv4.NewProtocol},
 				TransportProtocols: []stack.TransportProtocolFactory{udp.NewProtocol},
+				Clock:              clock,
 			})
 
 			if err := s.CreateNIC(nicID, e); err != nil {
@@ -3178,7 +3179,8 @@ func TestPacketQueing(t *testing.T) {
 			// Wait for a ARP request since link address resolution should be
 			// performed.
 			{
-				p, ok := e.ReadContext(context.Background())
+				clock.RunImmediatelyScheduledJobs()
+				p, ok := e.Read()
 				if !ok {
 					t.Fatalf("timed out waiting for packet")
 				}
@@ -3219,6 +3221,7 @@ func TestPacketQueing(t *testing.T) {
 			}
 
 			// Expect the response now that the link address has resolved.
+			clock.RunImmediatelyScheduledJobs()
 			test.checkResp(t, e)
 
 			// Since link resolution was already performed, it shouldn't be performed

pkg/tcpip/network/ipv6/icmp_test.go

@@ -16,7 +16,6 @@ package ipv6
 
 import (
 	"bytes"
-	"context"
 	"net"
 	"reflect"
 	"strings"
@@ -26,6 +25,7 @@ import (
 	"gvisor.dev/gvisor/pkg/tcpip"
 	"gvisor.dev/gvisor/pkg/tcpip/buffer"
 	"gvisor.dev/gvisor/pkg/tcpip/checker"
+	"gvisor.dev/gvisor/pkg/tcpip/faketime"
 	"gvisor.dev/gvisor/pkg/tcpip/header"
 	"gvisor.dev/gvisor/pkg/tcpip/link/channel"
 	"gvisor.dev/gvisor/pkg/tcpip/link/sniffer"
@@ -366,6 +366,8 @@ type testContext struct {
 
 	linkEP0 *channel.Endpoint
 	linkEP1 *channel.Endpoint
+
+	clock *faketime.ManualClock
 }
 
 type endpointWithResolutionCapability struct {
@@ -377,15 +379,19 @@ func (e endpointWithResolutionCapability) Capabilities() stack.LinkEndpointCapab
 }
 
 func newTestContext(t *testing.T) *testContext {
+	clock := faketime.NewManualClock()
 	c := &testContext{
 		s0: stack.New(stack.Options{
 			NetworkProtocols:   []stack.NetworkProtocolFactory{NewProtocol},
 			TransportProtocols: []stack.TransportProtocolFactory{icmp.NewProtocol6},
+			Clock:              clock,
 		}),
 		s1: stack.New(stack.Options{
 			NetworkProtocols:   []stack.NetworkProtocolFactory{NewProtocol},
 			TransportProtocols: []stack.TransportProtocolFactory{icmp.NewProtocol6},
+			Clock:              clock,
 		}),
+		clock: clock,
 	}
 
 	c.linkEP0 = channel.New(defaultChannelSize, defaultMTU, linkAddr0)
@@ -452,10 +458,14 @@ type routeArgs struct {
 	remoteLinkAddr tcpip.LinkAddress
 }
 
-func routeICMPv6Packet(t *testing.T, args routeArgs, fn func(*testing.T, header.ICMPv6)) {
+func routeICMPv6Packet(t *testing.T, clock *faketime.ManualClock, args routeArgs, fn func(*testing.T, header.ICMPv6)) {
 	t.Helper()
 
-	pi, _ := args.src.ReadContext(context.Background())
+	clock.RunImmediatelyScheduledJobs()
+	pi, ok := args.src.Read()
+	if !ok {
+		t.Fatal("packet didn't arrive")
+	}
 
 	{
 		pkt := stack.NewPacketBuffer(stack.PacketBufferOptions{
@@ -528,7 +538,7 @@ func TestLinkResolution(t *testing.T) {
 		{src: c.linkEP0, dst: c.linkEP1, typ: header.ICMPv6NeighborSolicit, remoteLinkAddr: header.EthernetAddressFromMulticastIPv6Address(header.SolicitedNodeAddr(lladdr1))},
 		{src: c.linkEP1, dst: c.linkEP0, typ: header.ICMPv6NeighborAdvert},
 	} {
-		routeICMPv6Packet(t, args, func(t *testing.T, icmpv6 header.ICMPv6) {
+		routeICMPv6Packet(t, c.clock, args, func(t *testing.T, icmpv6 header.ICMPv6) {
 			if got, want := tcpip.Address(icmpv6[8:][:16]), lladdr1; got != want {
 				t.Errorf("%d: got target = %s, want = %s", icmpv6.Type(), got, want)
 			}
@@ -539,7 +549,7 @@ func TestLinkResolution(t *testing.T) {
 		{src: c.linkEP0, dst: c.linkEP1, typ: header.ICMPv6EchoRequest},
 		{src: c.linkEP1, dst: c.linkEP0, typ: header.ICMPv6EchoReply},
 	} {
-		routeICMPv6Packet(t, args, nil)
+		routeICMPv6Packet(t, c.clock, args, nil)
 	}
 }
 
@@ -1320,7 +1330,7 @@ func TestPacketQueing(t *testing.T) {
 				}))
 			},
 			checkResp: func(t *testing.T, e *channel.Endpoint) {
-				p, ok := e.ReadContext(context.Background())
+				p, ok := e.Read()
 				if !ok {
 					t.Fatalf("timed out waiting for packet")
 				}
@@ -1366,7 +1376,7 @@ func TestPacketQueing(t *testing.T) {
 				}))
 			},
 			checkResp: func(t *testing.T, e *channel.Endpoint) {
-				p, ok := e.ReadContext(context.Background())
+				p, ok := e.Read()
 				if !ok {
 					t.Fatalf("timed out waiting for packet")
 				}
@@ -1391,9 +1401,11 @@ func TestPacketQueing(t *testing.T) {
 
 			e := channel.New(1, header.IPv6MinimumMTU, host1NICLinkAddr)
 			e.LinkEPCapabilities |= stack.CapabilityResolutionRequired
+			clock := faketime.NewManualClock()
 			s := stack.New(stack.Options{
 				NetworkProtocols:   []stack.NetworkProtocolFactory{NewProtocol},
 				TransportProtocols: []stack.TransportProtocolFactory{udp.NewProtocol},
+				Clock:              clock,
 			})
 
 			if err := s.CreateNIC(nicID, e); err != nil {
@@ -1416,7 +1428,8 @@ func TestPacketQueing(t *testing.T) {
 			// Wait for a neighbor solicitation since link address resolution should
 			// be performed.
 			{
-				p, ok := e.ReadContext(context.Background())
+				clock.RunImmediatelyScheduledJobs()
+				p, ok := e.Read()
 				if !ok {
 					t.Fatalf("timed out waiting for packet")
 				}
@@ -1470,6 +1483,7 @@ func TestPacketQueing(t *testing.T) {
 			}
 
 			// Expect the response now that the link address has resolved.
+			clock.RunImmediatelyScheduledJobs()
 			test.checkResp(t, e)
 
 			// Since link resolution was already performed, it shouldn't be performed

pkg/tcpip/network/ipv6/ndp_test.go

@@ -16,7 +16,6 @@ package ipv6
 
 import (
 	"bytes"
-	"context"
 	"math/rand"
 	"strings"
 	"testing"
@@ -400,8 +399,10 @@ func TestNeighborSolicitationResponse(t *testing.T) {
 
 	for _, test := range tests {
 		t.Run(test.name, func(t *testing.T) {
+			clock := faketime.NewManualClock()
 			s := stack.New(stack.Options{
 				NetworkProtocols: []stack.NetworkProtocolFactory{NewProtocol},
+				Clock:            clock,
 			})
 			e := channel.New(1, 1280, nicLinkAddr)
 			e.LinkEPCapabilities |= stack.CapabilityResolutionRequired
@@ -471,7 +472,8 @@ func TestNeighborSolicitationResponse(t *testing.T) {
 			}
 
 			if test.performsLinkResolution {
-				p, got := e.ReadContext(context.Background())
+				clock.RunImmediatelyScheduledJobs()
+				p, got := e.Read()
 				if !got {
 					t.Fatal("expected an NDP NS response")
 				}
@@ -526,7 +528,8 @@ func TestNeighborSolicitationResponse(t *testing.T) {
 				}))
 			}
 
-			p, got := e.ReadContext(context.Background())
+			clock.RunImmediatelyScheduledJobs()
+			p, got := e.Read()
 			if !got {
 				t.Fatal("expected an NDP NA response")
 			}
@@ -850,12 +853,12 @@ func TestNDPValidation(t *testing.T) {
 						routerOnly := stats.RouterOnlyPacketsDroppedByHost
 						typStat := typ.statCounter(stats)
 
-						icmp := header.ICMPv6(buffer.NewView(typ.size + len(typ.extraData)))
-						copy(icmp[typ.size:], typ.extraData)
-						icmp.SetType(typ.typ)
-						icmp.SetCode(test.code)
-						icmp.SetChecksum(header.ICMPv6Checksum(header.ICMPv6ChecksumParams{
-							Header:      icmp[:typ.size],
+						icmpH := header.ICMPv6(buffer.NewView(typ.size + len(typ.extraData)))
+						copy(icmpH[typ.size:], typ.extraData)
+						icmpH.SetType(typ.typ)
+						icmpH.SetCode(test.code)
+						icmpH.SetChecksum(header.ICMPv6Checksum(header.ICMPv6ChecksumParams{
+							Header:      icmpH[:typ.size],
 							Src:         lladdr0,
 							Dst:         lladdr1,
 							PayloadCsum: header.Checksum(typ.extraData /* initial */, 0),
@@ -881,7 +884,7 @@ func TestNDPValidation(t *testing.T) {
 							t.FailNow()
 						}
 
-						handleIPv6Payload(buffer.View(icmp), test.hopLimit, test.atomicFragment, ep)
+						handleIPv6Payload(buffer.View(icmpH), test.hopLimit, test.atomicFragment, ep)
 
 						// Rx count of the NDP packet should have increased.
 						if got := typStat.Value(); got != 1 {
@@ -1260,7 +1263,8 @@ func TestCheckDuplicateAddress(t *testing.T) {
 	snmc := header.SolicitedNodeAddr(lladdr0)
 	remoteLinkAddr := header.EthernetAddressFromMulticastIPv6Address(snmc)
 	checkDADMsg := func() {
-		p, ok := e.ReadContext(context.Background())
+		clock.RunImmediatelyScheduledJobs()
+		p, ok := e.Read()
 		if !ok {
 			t.Fatalf("expected %d-th DAD message", dadPacketsSent)
 		}

pkg/tcpip/stack/stack_test.go

@@ -2640,15 +2640,17 @@ func TestNICAutoGenAddrDoesDAD(t *testing.T) {
 	const nicID = 1
 
 	ndpDisp := ndpDispatcher{
-		dadC: make(chan ndpDADEvent),
+		dadC: make(chan ndpDADEvent, 1),
 	}
 	dadConfigs := stack.DefaultDADConfigurations()
+	clock := faketime.NewManualClock()
 	opts := stack.Options{
 		NetworkProtocols: []stack.NetworkProtocolFactory{ipv6.NewProtocolWithOptions(ipv6.Options{
 			AutoGenLinkLocal: true,
 			NDPDisp:          &ndpDisp,
 			DADConfigs:       dadConfigs,
 		})},
+		Clock: clock,
 	}
 
 	e := channel.New(int(dadConfigs.DupAddrDetectTransmits), 1280, linkAddr1)
@@ -2666,17 +2668,18 @@ func TestNICAutoGenAddrDoesDAD(t *testing.T) {
 	linkLocalAddr := header.LinkLocalAddr(linkAddr1)
 
 	// Wait for DAD to resolve.
+	clock.Advance(time.Duration(dadConfigs.DupAddrDetectTransmits) * dadConfigs.RetransmitTimer)
 	select {
-	case <-time.After(time.Duration(dadConfigs.DupAddrDetectTransmits)*dadConfigs.RetransmitTimer + time.Second):
+	case e := <-ndpDisp.dadC:
+		if diff := checkDADEvent(e, nicID, linkLocalAddr, &stack.DADSucceeded{}); diff != "" {
+			t.Errorf("dad event mismatch (-want +got):\n%s", diff)
+		}
+	default:
 		// We should get a resolution event after 1s (default time to
 		// resolve as per default NDP configurations). Waiting for that
 		// resolution time + an extra 1s without a resolution event
 		// means something is wrong.
 		t.Fatal("timed out waiting for DAD resolution")
-	case e := <-ndpDisp.dadC:
-		if diff := checkDADEvent(e, nicID, linkLocalAddr, &stack.DADSucceeded{}); diff != "" {
-			t.Errorf("dad event mismatch (-want +got):\n%s", diff)
-		}
 	}
 	if err := checkGetMainNICAddress(s, nicID, header.IPv6ProtocolNumber, tcpip.AddressWithPrefix{Address: linkLocalAddr, PrefixLen: header.IPv6LinkLocalPrefix.PrefixLen}); err != nil {
 		t.Fatal(err)
@@ -3307,8 +3310,9 @@ func TestDoDADWhenNICEnabled(t *testing.T) {
 	const nicID = 1
 
 	ndpDisp := ndpDispatcher{
-		dadC: make(chan ndpDADEvent),
+		dadC: make(chan ndpDADEvent, 1),
 	}
+	clock := faketime.NewManualClock()
 	opts := stack.Options{
 		NetworkProtocols: []stack.NetworkProtocolFactory{ipv6.NewProtocolWithOptions(ipv6.Options{
 			DADConfigs: stack.DADConfigurations{
@@ -3317,6 +3321,7 @@ func TestDoDADWhenNICEnabled(t *testing.T) {
 			},
 			NDPDisp: &ndpDisp,
 		})},
+		Clock: clock,
 	}
 
 	e := channel.New(dadTransmits, 1280, linkAddr1)
@@ -3361,13 +3366,14 @@ func TestDoDADWhenNICEnabled(t *testing.T) {
 	}
 
 	// Wait for DAD to resolve.
+	clock.Advance(dadTransmits * retransmitTimer)
 	select {
-	case <-time.After(dadTransmits*retransmitTimer + defaultAsyncPositiveEventTimeout):
-		t.Fatal("timed out waiting for DAD resolution")
 	case e := <-ndpDisp.dadC:
 		if diff := checkDADEvent(e, nicID, addr.AddressWithPrefix.Address, &stack.DADSucceeded{}); diff != "" {
 			t.Errorf("dad event mismatch (-want +got):\n%s", diff)
 		}
+	default:
+		t.Fatal("timed out waiting for DAD resolution")
 	}
 	if addrs := s.AllAddresses()[nicID]; !containsV6Addr(addrs, addr.AddressWithPrefix) {
 		t.Fatalf("got s.AllAddresses()[%d] = %+v, want = %+v", nicID, addrs, addr)

pkg/tcpip/timer_test.go

@@ -129,10 +129,14 @@ func TestJobReschedule(t *testing.T) {
 	wg.Wait()
 }
 
+func stdClockWithAfter() (tcpip.Clock, func(time.Duration) <-chan time.Time) {
+	return tcpip.NewStdClock(), time.After
+}
+
 func TestJobExecution(t *testing.T) {
 	t.Parallel()
 
-	clock := tcpip.NewStdClock()
+	clock, after := stdClockWithAfter()
 	var lock sync.Mutex
 	ch := make(chan struct{})
 
@@ -144,7 +148,7 @@ func TestJobExecution(t *testing.T) {
 	// Wait for timer to fire.
 	select {
 	case <-ch:
-	case <-time.After(middleDuration):
+	case <-after(middleDuration):
 		t.Fatal("timed out waiting for timer to fire")
 	}
 
@@ -152,14 +156,14 @@ func TestJobExecution(t *testing.T) {
 	select {
 	case <-ch:
 		t.Fatal("no other timers should have fired")
-	case <-time.After(middleDuration):
+	case <-after(middleDuration):
 	}
 }
 
 func TestCancellableTimerResetFromLongDuration(t *testing.T) {
 	t.Parallel()
 
-	clock := tcpip.NewStdClock()
+	clock, after := stdClockWithAfter()
 	var lock sync.Mutex
 	ch := make(chan struct{})
 
@@ -175,7 +179,7 @@ func TestCancellableTimerResetFromLongDuration(t *testing.T) {
 	// Wait for timer to fire.
 	select {
 	case <-ch:
-	case <-time.After(middleDuration):
+	case <-after(middleDuration):
 		t.Fatal("timed out waiting for timer to fire")
 	}
 
@@ -183,14 +187,14 @@ func TestCancellableTimerResetFromLongDuration(t *testing.T) {
 	select {
 	case <-ch:
 		t.Fatal("no other timers should have fired")
-	case <-time.After(middleDuration):
+	case <-after(middleDuration):
 	}
 }
 
 func TestJobRescheduleFromShortDuration(t *testing.T) {
 	t.Parallel()
 
-	clock := tcpip.NewStdClock()
+	clock, after := stdClockWithAfter()
 	var lock sync.Mutex
 	ch := make(chan struct{})
 
@@ -204,7 +208,7 @@ func TestJobRescheduleFromShortDuration(t *testing.T) {
 	select {
 	case <-ch:
 		t.Fatal("timer fired after being stopped")
-	case <-time.After(middleDuration):
+	case <-after(middleDuration):
 	}
 
 	job.Schedule(shortDuration)
@@ -212,7 +216,7 @@ func TestJobRescheduleFromShortDuration(t *testing.T) {
 	// Wait for timer to fire.
 	select {
 	case <-ch:
-	case <-time.After(middleDuration):
+	case <-after(middleDuration):
 		t.Fatal("timed out waiting for timer to fire")
 	}
 
@@ -220,14 +224,14 @@ func TestJobRescheduleFromShortDuration(t *testing.T) {
 	select {
 	case <-ch:
 		t.Fatal("no other timers should have fired")
-	case <-time.After(middleDuration):
+	case <-after(middleDuration):
 	}
 }
 
 func TestJobImmediatelyCancel(t *testing.T) {
 	t.Parallel()
 
-	clock := tcpip.NewStdClock()
+	clock, after := stdClockWithAfter()
 	var lock sync.Mutex
 	ch := make(chan struct{})
 
@@ -243,14 +247,19 @@ func TestJobImmediatelyCancel(t *testing.T) {
 	select {
 	case <-ch:
 		t.Fatal("timer fired after being stopped")
-	case <-time.After(middleDuration):
+	case <-after(middleDuration):
 	}
 }
 
+func stdClockWithAfterAndSleep() (tcpip.Clock, func(time.Duration) <-chan time.Time, func(time.Duration)) {
+	clock, after := stdClockWithAfter()
+	return clock, after, time.Sleep
+}
+
 func TestJobCancelledRescheduleWithoutLock(t *testing.T) {
 	t.Parallel()
 
-	clock := tcpip.NewStdClock()
+	clock, after, sleep := stdClockWithAfterAndSleep()
 	var lock sync.Mutex
 	ch := make(chan struct{})
 
@@ -265,7 +274,7 @@ func TestJobCancelledRescheduleWithoutLock(t *testing.T) {
 
 		lock.Lock()
 		// Sleep until the timer fires and gets blocked trying to take the lock.
-		time.Sleep(middleDuration * 2)
+		sleep(middleDuration * 2)
 		job.Cancel()
 		lock.Unlock()
 	}
@@ -275,14 +284,14 @@ func TestJobCancelledRescheduleWithoutLock(t *testing.T) {
 	select {
 	case <-ch:
 		t.Fatal("timer fired after being stopped")
-	case <-time.After(middleDuration * 2):
+	case <-after(middleDuration * 2):
 	}
 }
 
 func TestManyCancellableTimerResetAfterBlockedOnLock(t *testing.T) {
 	t.Parallel()
 
-	clock := tcpip.NewStdClock()
+	clock, after, sleep := stdClockWithAfterAndSleep()
 	var lock sync.Mutex
 	ch := make(chan struct{})
 
@@ -291,7 +300,7 @@ func TestManyCancellableTimerResetAfterBlockedOnLock(t *testing.T) {
 	job.Schedule(shortDuration)
 	for i := 0; i < 10; i++ {
 		// Sleep until the timer fires and gets blocked trying to take the lock.
-		time.Sleep(middleDuration)
+		sleep(middleDuration)
 		job.Cancel()
 		job.Schedule(shortDuration)
 	}
@@ -300,7 +309,7 @@ func TestManyCancellableTimerResetAfterBlockedOnLock(t *testing.T) {
 	// Wait for double the duration for the last timer to fire.
 	select {
 	case <-ch:
-	case <-time.After(middleDuration):
+	case <-after(middleDuration):
 		t.Fatal("timed out waiting for timer to fire")
 	}
 
@@ -308,14 +317,14 @@ func TestManyCancellableTimerResetAfterBlockedOnLock(t *testing.T) {
 	select {
 	case <-ch:
 		t.Fatal("no other timers should have fired")
-	case <-time.After(middleDuration):
+	case <-after(middleDuration):
 	}
 }
 
 func TestManyJobReschedulesUnderLock(t *testing.T) {
 	t.Parallel()
 
-	clock := tcpip.NewStdClock()
+	clock, after := stdClockWithAfter()
 	var lock sync.Mutex
 	ch := make(chan struct{})
 
@@ -331,7 +340,7 @@ func TestManyJobReschedulesUnderLock(t *testing.T) {
 	// Wait for double the duration for the last timer to fire.
 	select {
 	case <-ch:
-	case <-time.After(middleDuration):
+	case <-after(middleDuration):
 		t.Fatal("timed out waiting for timer to fire")
 	}
 
@@ -339,6 +348,6 @@ func TestManyJobReschedulesUnderLock(t *testing.T) {
 	select {
 	case <-ch:
 		t.Fatal("no other timers should have fired")
-	case <-time.After(middleDuration):
+	case <-after(middleDuration):
 	}
 }

pkg/tcpip/transport/udp/BUILD

@@ -49,6 +49,7 @@ go_test(
         "//pkg/tcpip",
         "//pkg/tcpip/buffer",
         "//pkg/tcpip/checker",
+        "//pkg/tcpip/faketime",
         "//pkg/tcpip/header",
         "//pkg/tcpip/link/channel",
         "//pkg/tcpip/link/loopback",

pkg/tcpip/transport/udp/udp_test.go

@@ -16,17 +16,16 @@ package udp_test
 
 import (
 	"bytes"
-	"context"
 	"fmt"
 	"io/ioutil"
 	"math/rand"
 	"testing"
-	"time"
 
 	"github.com/google/go-cmp/cmp"
 	"gvisor.dev/gvisor/pkg/tcpip"
 	"gvisor.dev/gvisor/pkg/tcpip/buffer"
 	"gvisor.dev/gvisor/pkg/tcpip/checker"
+	"gvisor.dev/gvisor/pkg/tcpip/faketime"
 	"gvisor.dev/gvisor/pkg/tcpip/header"
 	"gvisor.dev/gvisor/pkg/tcpip/link/channel"
 	"gvisor.dev/gvisor/pkg/tcpip/link/loopback"
@@ -298,16 +297,18 @@ type testContext struct {
 
 func newDualTestContext(t *testing.T, mtu uint32) *testContext {
 	t.Helper()
-	return newDualTestContextWithOptions(t, mtu, stack.Options{
-		NetworkProtocols:   []stack.NetworkProtocolFactory{ipv4.NewProtocol, ipv6.NewProtocol},
-		TransportProtocols: []stack.TransportProtocolFactory{udp.NewProtocol, icmp.NewProtocol6, icmp.NewProtocol4},
-		HandleLocal:        true,
-	})
+	return newDualTestContextWithHandleLocal(t, mtu, true)
 }
 
-func newDualTestContextWithOptions(t *testing.T, mtu uint32, options stack.Options) *testContext {
+func newDualTestContextWithHandleLocal(t *testing.T, mtu uint32, handleLocal bool) *testContext {
 	t.Helper()
 
+	options := stack.Options{
+		NetworkProtocols:   []stack.NetworkProtocolFactory{ipv4.NewProtocol, ipv6.NewProtocol},
+		TransportProtocols: []stack.TransportProtocolFactory{udp.NewProtocol, icmp.NewProtocol6, icmp.NewProtocol4},
+		HandleLocal:        handleLocal,
+		Clock:              &faketime.NullClock{},
+	}
 	s := stack.New(options)
 	ep := channel.New(256, mtu, "")
 	wep := stack.LinkEndpoint(ep)
@@ -378,9 +379,7 @@ func (c *testContext) createEndpointForFlow(flow testFlow) {
 func (c *testContext) getPacketAndVerify(flow testFlow, checkers ...checker.NetworkChecker) []byte {
 	c.t.Helper()
 
-	ctx, cancel := context.WithTimeout(context.Background(), 2*time.Second)
-	defer cancel()
-	p, ok := c.linkEP.ReadContext(ctx)
+	p, ok := c.linkEP.Read()
 	if !ok {
 		c.t.Fatalf("Packet wasn't written out")
 		return nil
@@ -534,7 +533,9 @@ func newMinPayload(minSize int) []byte {
 func TestBindToDeviceOption(t *testing.T) {
 	s := stack.New(stack.Options{
 		NetworkProtocols:   []stack.NetworkProtocolFactory{ipv4.NewProtocol},
-		TransportProtocols: []stack.TransportProtocolFactory{udp.NewProtocol}})
+		TransportProtocols: []stack.TransportProtocolFactory{udp.NewProtocol},
+		Clock:              &faketime.NullClock{},
+	})
 
 	ep, err := s.NewEndpoint(udp.ProtocolNumber, ipv4.ProtocolNumber, &waiter.Queue{})
 	if err != nil {
@@ -606,7 +607,7 @@ func testReadInternal(c *testContext, flow testFlow, packetShouldBeDropped, expe
 		case <-ch:
 			res, err = c.ep.Read(&buf, tcpip.ReadOptions{NeedRemoteAddr: true})
 
-		case <-time.After(300 * time.Millisecond):
+		default:
 			if packetShouldBeDropped {
 				return // expected to time out
 			}
@@ -820,11 +821,7 @@ func TestV4ReadSelfSource(t *testing.T) {
 		{"NoHandleLocal", true, &tcpip.ErrWouldBlock{}, 1},
 	} {
 		t.Run(tt.name, func(t *testing.T) {
-			c := newDualTestContextWithOptions(t, defaultMTU, stack.Options{
-				NetworkProtocols:   []stack.NetworkProtocolFactory{ipv4.NewProtocol, ipv6.NewProtocol},
-				TransportProtocols: []stack.TransportProtocolFactory{udp.NewProtocol},
-				HandleLocal:        tt.handleLocal,
-			})
+			c := newDualTestContextWithHandleLocal(t, defaultMTU, tt.handleLocal)
 			defer c.cleanup()
 
 			c.createEndpointForFlow(unicastV4)
@@ -1034,17 +1031,17 @@ func testWriteAndVerifyInternal(c *testContext, flow testFlow, setDest bool, che
 	payload := testWriteNoVerify(c, flow, setDest)
 	// Received the packet and check the payload.
 	b := c.getPacketAndVerify(flow, checkers...)
-	var udp header.UDP
+	var udpH header.UDP
 	if flow.isV4() {
-		udp = header.UDP(header.IPv4(b).Payload())
+		udpH = header.IPv4(b).Payload()
 	} else {
-		udp = header.UDP(header.IPv6(b).Payload())
+		udpH = header.IPv6(b).Payload()
 	}
-	if !bytes.Equal(payload, udp.Payload()) {
-		c.t.Fatalf("Bad payload: got %x, want %x", udp.Payload(), payload)
+	if !bytes.Equal(payload, udpH.Payload()) {
+		c.t.Fatalf("Bad payload: got %x, want %x", udpH.Payload(), payload)
 	}
 
-	return udp.SourcePort()
+	return udpH.SourcePort()
 }
 
 func testDualWrite(c *testContext) uint16 {
@@ -1198,7 +1195,7 @@ func TestWriteOnConnectedInvalidPort(t *testing.T) {
 			r.Reset(payload)
 			n, err := c.ep.Write(&r, writeOpts)
 			if err != nil {
-				c.t.Fatalf("c.ep.Write(...) = %+s, want nil", err)
+				c.t.Fatalf("c.ep.Write(...) = %s, want nil", err)
 			}
 			if got, want := n, int64(len(payload)); got != want {
 				c.t.Fatalf("c.ep.Write(...) wrote %d bytes, want %d bytes", got, want)
@@ -1614,6 +1611,7 @@ func TestTTL(t *testing.T) {
 				}
 				s := stack.New(stack.Options{
 					NetworkProtocols: []stack.NetworkProtocolFactory{p},
+					Clock:            &faketime.NullClock{},
 				})
 				ep := s.NetworkProtocolInstance(n).NewEndpoint(&testInterface{}, nil)
 				wantTTL = ep.DefaultTTL()
@@ -1759,7 +1757,7 @@ func TestReceiveTosTClass(t *testing.T) {
 					c.t.Errorf("got GetSockOptBool(%s) = %t, want = %t", name, v, false)
 				}
 
-				want := true
+				const want = true
 				optionSetter(want)
 
 				got := optionGetter()
@@ -1889,18 +1887,14 @@ func TestV4UnknownDestination(t *testing.T) {
 				}
 			}
 			if !tc.icmpRequired {
-				ctx, cancel := context.WithTimeout(context.Background(), time.Second)
-				defer cancel()
-				if p, ok := c.linkEP.ReadContext(ctx); ok {
+				if p, ok := c.linkEP.Read(); ok {
 					t.Fatalf("unexpected packet received: %+v", p)
 				}
 				return
 			}
 
 			// ICMP required.
-			ctx, cancel := context.WithTimeout(context.Background(), time.Second)
-			defer cancel()
-			p, ok := c.linkEP.ReadContext(ctx)
+			p, ok := c.linkEP.Read()
 			if !ok {
 				t.Fatalf("packet wasn't written out")
 				return
@@ -1987,18 +1981,14 @@ func TestV6UnknownDestination(t *testing.T) {
 				}
 			}
 			if !tc.icmpRequired {
-				ctx, cancel := context.WithTimeout(context.Background(), time.Second)
-				defer cancel()
-				if p, ok := c.linkEP.ReadContext(ctx); ok {
+				if p, ok := c.linkEP.Read(); ok {
 					t.Fatalf("unexpected packet received: %+v", p)
 				}
 				return
 			}
 
 			// ICMP required.
-			ctx, cancel := context.WithTimeout(context.Background(), time.Second)
-			defer cancel()
-			p, ok := c.linkEP.ReadContext(ctx)
+			p, ok := c.linkEP.Read()
 			if !ok {
 				t.Fatalf("packet wasn't written out")
 				return
@@ -2486,6 +2476,7 @@ func TestOutgoingSubnetBroadcast(t *testing.T) {
 			s := stack.New(stack.Options{
 				NetworkProtocols:   []stack.NetworkProtocolFactory{ipv4.NewProtocol, ipv6.NewProtocol},
 				TransportProtocols: []stack.TransportProtocolFactory{udp.NewProtocol},
+				Clock:              &faketime.NullClock{},
 			})
 			e := channel.New(0, defaultMTU, "")
 			if err := s.CreateNIC(nicID1, e); err != nil {