Use time.Duration for IGMP Max Response Time field

Bug #4682

PiperOrigin-RevId: 343993297

pkg/tcpip/checker/checker.go

@@ -20,6 +20,7 @@ import (
 	"encoding/binary"
 	"reflect"
 	"testing"
+	"time"
 
 	"github.com/google/go-cmp/cmp"
 	"gvisor.dev/gvisor/pkg/tcpip"
@@ -1267,7 +1268,7 @@ func IGMPType(want header.IGMPType) TransportChecker {
 }
 
 // IGMPMaxRespTime creates a checker that checks the IGMP Max Resp Time field.
-func IGMPMaxRespTime(want byte) TransportChecker {
+func IGMPMaxRespTime(want time.Duration) TransportChecker {
 	return func(t *testing.T, h header.Transport) {
 		t.Helper()
 
@@ -1276,7 +1277,7 @@ func IGMPMaxRespTime(want byte) TransportChecker {
 			t.Fatalf("got transport header = %T, want = header.IGMP", h)
 		}
 		if got := igmp.MaxRespTime(); got != want {
-			t.Errorf("got igmp.MaxRespTime() = %d, want = %d", got, want)
+			t.Errorf("got igmp.MaxRespTime() = %s, want = %s", got, want)
 		}
 	}
 }

pkg/tcpip/header/igmp.go

@@ -17,6 +17,7 @@ package header
 import (
 	"encoding/binary"
 	"fmt"
+	"time"
 
 	"gvisor.dev/gvisor/pkg/tcpip"
 )
@@ -103,7 +104,15 @@ func (b IGMP) SetType(t IGMPType) { b[igmpTypeOffset] = byte(t) }
 // MaxRespTime gets the MaxRespTimeField. This is meaningful only in Membership
 // Query messages, in other cases it is set to 0 by the sender and ignored by
 // the receiver.
-func (b IGMP) MaxRespTime() byte { return b[igmpMaxRespTimeOffset] }
+func (b IGMP) MaxRespTime() time.Duration {
+	// As per RFC 2236 section 2.2,
+	//
+	//  The Max Response Time field is meaningful only in Membership Query
+	//  messages, and specifies the maximum allowed time before sending a
+	//  responding report in units of 1/10 second.  In all other messages, it
+	//  is set to zero by the sender and ignored by receivers.
+	return DecisecondToDuration(b[igmpMaxRespTimeOffset])
+}
 
 // SetMaxRespTime sets the MaxRespTimeField.
 func (b IGMP) SetMaxRespTime(m byte) { b[igmpMaxRespTimeOffset] = m }
@@ -164,3 +173,9 @@ func IGMPCalculateChecksum(h IGMP) uint16 {
 	h.SetChecksum(existingXsum)
 	return xsum
 }
+
+// DecisecondToDuration converts a value representing deci-seconds to a
+// time.Duration.
+func DecisecondToDuration(ds uint8) time.Duration {
+	return time.Duration(ds) * time.Second / 10
+}

pkg/tcpip/header/igmp_test.go

@@ -16,6 +16,7 @@ package header_test
 
 import (
 	"testing"
+	"time"
 
 	"gvisor.dev/gvisor/pkg/tcpip"
 	"gvisor.dev/gvisor/pkg/tcpip/header"
@@ -23,10 +24,11 @@ import (
 
 // TestIGMPHeader tests the functions within header.igmp
 func TestIGMPHeader(t *testing.T) {
+	const maxRespTimeTenthSec = 0xF0
 	b := []byte{
-		0x11,       // IGMP Type, Membership Query
-		0xF0,       // Maximum Response Time
-		0xC0, 0xC0, // Checksum
+		0x11,                // IGMP Type, Membership Query
+		maxRespTimeTenthSec, // Maximum Response Time
+		0xC0, 0xC0,          // Checksum
 		0x01, 0x02, 0x03, 0x04, // Group Address
 	}
 
@@ -36,8 +38,8 @@ func TestIGMPHeader(t *testing.T) {
 		t.Errorf("got igmpHeader.Type() = %x, want = %x", got, want)
 	}
 
-	if got, want := igmpHeader.MaxRespTime(), byte(0xF0); got != want {
-		t.Errorf("got igmpHeader.MaxRespTime() = %x, want = %x", got, want)
+	if got, want := igmpHeader.MaxRespTime(), header.DecisecondToDuration(maxRespTimeTenthSec); got != want {
+		t.Errorf("got igmpHeader.MaxRespTime() = %s, want = %s", got, want)
 	}
 
 	if got, want := igmpHeader.Checksum(), uint16(0xC0C0); got != want {
@@ -59,8 +61,8 @@ func TestIGMPHeader(t *testing.T) {
 
 	respTime := byte(0x02)
 	igmpHeader.SetMaxRespTime(respTime)
-	if got := igmpHeader.MaxRespTime(); got != respTime {
-		t.Errorf("got igmpHeader.MaxRespTime() = %x, want = %x", got, respTime)
+	if got, want := igmpHeader.MaxRespTime(), header.DecisecondToDuration(respTime); got != want {
+		t.Errorf("got igmpHeader.MaxRespTime() = %s, want = %s", got, want)
 	}
 
 	checksum := uint16(0x0102)
@@ -99,3 +101,10 @@ func TestIGMPChecksum(t *testing.T) {
 		t.Errorf("got IGMPCalculateChecksum = %x, want %x", got, checksum)
 	}
 }
+
+func TestDecisecondToDuration(t *testing.T) {
+	const valueInDeciseconds = 5
+	if got, want := header.DecisecondToDuration(valueInDeciseconds), valueInDeciseconds*time.Second/10; got != want {
+		t.Fatalf("got header.DecisecondToDuration(%d) = %s, want = %s", valueInDeciseconds, got, want)
+	}
+}

pkg/tcpip/network/ipv4/igmp.go

@@ -35,15 +35,18 @@ const (
 	// See note on igmpState.igmpV1Present for more detail.
 	v1RouterPresentTimeout = 400 * time.Second
 
-	// v1MaxRespTimeTenthSec from RFC 2236 Section 4, Page 5. "The IGMPv1 router
+	// v1MaxRespTime from RFC 2236 Section 4, Page 5. "The IGMPv1 router
 	// will send General Queries with the Max Response Time set to 0. This MUST
 	// be interpreted as a value of 100 (10 seconds)."
-	v1MaxRespTimeTenthSec = 100
+	//
+	// Note that the Max Response Time field is a value in units of deciseconds.
+	v1MaxRespTime = 10 * time.Second
 
-	// UnsolicitedReportIntervalMaxTenthSec from RFC 2236 Section 8.10, Page 19.
-	// As all IGMP delay timers are set to a random value between 0 and the
-	// interval, this is technically a maximum.
-	UnsolicitedReportIntervalMaxTenthSec = 100
+	// UnsolicitedReportIntervalMax is the maximum delay between sending
+	// unsolicited IGMP reports.
+	//
+	// Obtained from RFC 2236 Section 8.10, Page 19.
+	UnsolicitedReportIntervalMax = 10 * time.Second
 )
 
 // igmpState is the per-interface IGMP state.
@@ -185,7 +188,7 @@ func (igmp *igmpState) handleIGMP(pkt *stack.PacketBuffer) {
 	}
 }
 
-func (igmp *igmpState) handleMembershipQuery(groupAddress tcpip.Address, maxRespTime byte) {
+func (igmp *igmpState) handleMembershipQuery(groupAddress tcpip.Address, maxRespTime time.Duration) {
 	igmp.mu.Lock()
 	defer igmp.mu.Unlock()
 
@@ -196,7 +199,7 @@ func (igmp *igmpState) handleMembershipQuery(groupAddress tcpip.Address, maxResp
 		igmp.mu.igmpV1Job.Cancel()
 		igmp.mu.igmpV1Job.Schedule(v1RouterPresentTimeout)
 		igmp.mu.igmpV1Present = true
-		maxRespTime = v1MaxRespTimeTenthSec
+		maxRespTime = v1MaxRespTime
 	}
 
 	// IPv4Any is the General Query Address.
@@ -215,7 +218,7 @@ func (igmp *igmpState) handleMembershipQuery(groupAddress tcpip.Address, maxResp
 // modify IGMP state directly.
 //
 // Precondition: igmp.mu MUST be read locked.
-func (igmp *igmpState) setDelayTimerForAddressRLocked(groupAddress tcpip.Address, info *membershipInfo, maxRespTime byte) {
+func (igmp *igmpState) setDelayTimerForAddressRLocked(groupAddress tcpip.Address, info *membershipInfo, maxRespTime time.Duration) {
 	if info.state == delayingMember {
 		// As per RFC 2236 Section 3, page 3: "If a timer for the group is already
 		// running, it is reset to the random value only if the requested Max
@@ -352,7 +355,7 @@ func (igmp *igmpState) joinGroup(groupAddress tcpip.Address) *tcpip.Error {
 	// it should immediately transmit an unsolicited Version 2 Membership Report
 	// for that group" ... "it is recommended that it be repeated"
 	igmp.sendReportLocked(groupAddress)
-	igmp.setDelayTimerForAddressRLocked(groupAddress, &info, UnsolicitedReportIntervalMaxTenthSec)
+	igmp.setDelayTimerForAddressRLocked(groupAddress, &info, UnsolicitedReportIntervalMax)
 	igmp.mu.memberships[groupAddress] = info
 
 	return nil
@@ -383,16 +386,7 @@ func (igmp *igmpState) leaveGroup(groupAddress tcpip.Address) {
 }
 
 // RFC 2236 Section 3, Page 3: The response time is set to a "random value...
-// selected from the range (0, Max Response Time]" where Max Resp Time is given
-// in units of 1/10 of a second.
-func (igmp *igmpState) calculateDelayTimerDuration(maxRespTime byte) time.Duration {
-	maxRespTimeDuration := DecisecondToSecond(maxRespTime)
-	return time.Duration(igmp.ep.protocol.stack.Rand().Int63n(int64(maxRespTimeDuration)))
-}
-
-// DecisecondToSecond converts a byte representing deci-seconds to a Duration
-// type. This helper function exists because the IGMP stack sends and receives
-// Max Response Times in deci-seconds.
-func DecisecondToSecond(ds byte) time.Duration {
-	return time.Duration(ds) * time.Second / 10
+// selected from the range (0, Max Response Time]".
+func (igmp *igmpState) calculateDelayTimerDuration(maxRespTime time.Duration) time.Duration {
+	return time.Duration(igmp.ep.protocol.stack.Rand().Int63n(int64(maxRespTime)))
 }

pkg/tcpip/network/ipv4/igmp_test.go

@@ -15,7 +15,9 @@
 package ipv4_test
 
 import (
+	"fmt"
 	"testing"
+	"time"
 
 	"gvisor.dev/gvisor/pkg/tcpip"
 	"gvisor.dev/gvisor/pkg/tcpip/buffer"
@@ -35,9 +37,16 @@ const (
 )
 
 var (
-	// unsolicitedReportIntervalMax is the maximum amount of time the NIC will
-	// wait before sending an unsolicited report after joining a multicast group.
-	unsolicitedReportIntervalMax = ipv4.DecisecondToSecond(ipv4.UnsolicitedReportIntervalMaxTenthSec)
+	// unsolicitedReportIntervalMaxTenthSec is the maximum amount of time the NIC
+	// will wait before sending an unsolicited report after joining a multicast
+	// group, in deciseconds.
+	unsolicitedReportIntervalMaxTenthSec = func() uint8 {
+		const decisecond = time.Second / 10
+		if ipv4.UnsolicitedReportIntervalMax%decisecond != 0 {
+			panic(fmt.Sprintf("UnsolicitedReportIntervalMax of %d is a lossy conversion to deciseconds", ipv4.UnsolicitedReportIntervalMax))
+		}
+		return uint8(ipv4.UnsolicitedReportIntervalMax / decisecond)
+	}()
 )
 
 // validateIgmpPacket checks that a passed PacketInfo is an IPv4 IGMP packet
@@ -51,7 +60,7 @@ func validateIgmpPacket(t *testing.T, p channel.PacketInfo, remoteAddress tcpip.
 		checker.DstAddr(remoteAddress),
 		checker.IGMP(
 			checker.IGMPType(igmpType),
-			checker.IGMPMaxRespTime(maxRespTime),
+			checker.IGMPMaxRespTime(header.DecisecondToDuration(maxRespTime)),
 			checker.IGMPGroupAddress(groupAddress),
 		),
 	)
@@ -134,7 +143,7 @@ func TestIgmpDisabled(t *testing.T) {
 	// Inject a General Membership Query, which is an IGMP Membership Query with
 	// a zeroed Group Address (IPv4Any) to verify that it does not reach the
 	// handler.
-	createAndInjectIGMPPacket(e, header.IGMPMembershipQuery, ipv4.UnsolicitedReportIntervalMaxTenthSec, header.IPv4Any)
+	createAndInjectIGMPPacket(e, header.IGMPMembershipQuery, unsolicitedReportIntervalMaxTenthSec, header.IPv4Any)
 
 	if got := s.Stats().IGMP.PacketsReceived.MembershipQuery.Value(); got != 0 {
 		t.Fatalf("got Membership Queries received = %d, want = 0", got)
@@ -161,7 +170,7 @@ func TestIgmpReceivesIGMPMessages(t *testing.T) {
 		{
 			name:         "General Membership Query",
 			headerType:   header.IGMPMembershipQuery,
-			maxRespTime:  ipv4.UnsolicitedReportIntervalMaxTenthSec,
+			maxRespTime:  unsolicitedReportIntervalMaxTenthSec,
 			groupAddress: header.IPv4Any,
 			statCounter: func(stats tcpip.IGMPReceivedPacketStats) *tcpip.StatCounter {
 				return stats.MembershipQuery
@@ -234,12 +243,12 @@ func TestIgmpJoinGroup(t *testing.T) {
 	}
 
 	// Verify the second Membership Report is sent after a random interval up to
-	// the unsolicitedReportIntervalMax.
+	// the maximum unsolicited report interval.
 	p, ok = e.Read()
 	if ok {
 		t.Fatalf("sent unexpected packet, expected V2MembershipReport only after advancing the clock = %+v", p.Pkt)
 	}
-	clock.Advance(unsolicitedReportIntervalMax)
+	clock.Advance(ipv4.UnsolicitedReportIntervalMax)
 	p, ok = e.Read()
 	if !ok {
 		t.Fatal("unable to Read IGMP packet, expected V2MembershipReport")
@@ -273,13 +282,13 @@ func TestIgmpLeaveGroup(t *testing.T) {
 	}
 
 	// Verify the second Membership Report is sent after a random interval up to
-	// the unsolicitedReportIntervalMax, and is sent to the multicast address
-	// being joined.
+	// the maximum unsolicited report interval, and is sent to the multicast
+	// address being joined.
 	p, ok = e.Read()
 	if ok {
 		t.Fatalf("sent unexpected packet, expected V2MembershipReport only after advancing the clock = %+v", p.Pkt)
 	}
-	clock.Advance(unsolicitedReportIntervalMax)
+	clock.Advance(ipv4.UnsolicitedReportIntervalMax)
 	p, ok = e.Read()
 	if !ok {
 		t.Fatal("unable to Read IGMP packet, expected V2MembershipReport")
@@ -334,7 +343,7 @@ func TestIgmpJoinLeaveGroup(t *testing.T) {
 	// Wait for the standard IGMP Unsolicited Report Interval duration before
 	// verifying that the unsolicited Membership Report was sent after leaving
 	// the group.
-	clock.Advance(unsolicitedReportIntervalMax)
+	clock.Advance(ipv4.UnsolicitedReportIntervalMax)
 	if got := s.Stats().IGMP.PacketsSent.V2MembershipReport.Value(); got != 1 {
 		t.Fatalf("got V2MembershipReport messages sent = %d, want = 1", got)
 	}
@@ -365,7 +374,7 @@ func TestIgmpMembershipQueryReport(t *testing.T) {
 	if ok {
 		t.Fatalf("sent unexpected packet, expected V2MembershipReport only after advancing the clock = %+v", p.Pkt)
 	}
-	clock.Advance(unsolicitedReportIntervalMax)
+	clock.Advance(ipv4.UnsolicitedReportIntervalMax)
 	p, ok = e.Read()
 	if !ok {
 		t.Fatal("unable to Read IGMP packet, expected V2MembershipReport")
@@ -384,7 +393,7 @@ func TestIgmpMembershipQueryReport(t *testing.T) {
 	if ok {
 		t.Fatalf("sent unexpected packet, expected V2MembershipReport only after advancing the clock = %+v", p.Pkt)
 	}
-	clock.Advance(ipv4.DecisecondToSecond(maxRespTimeDS))
+	clock.Advance(header.DecisecondToDuration(maxRespTimeDS))
 	p, ok = e.Read()
 	if !ok {
 		t.Fatal("unable to Read IGMP packet, expected V2MembershipReport")
@@ -428,7 +437,7 @@ func TestIgmpMultipleHosts(t *testing.T) {
 	// Wait to be sure that no Leave Group messages were sent up to the max
 	// unsolicited report interval since it was not the last host to join this
 	// group.
-	clock.Advance(unsolicitedReportIntervalMax)
+	clock.Advance(ipv4.UnsolicitedReportIntervalMax)
 	if got := s.Stats().IGMP.PacketsSent.LeaveGroup.Value(); got != 0 {
 		t.Fatalf("got LeaveGroup messages sent = %d, want = 0", got)
 	}
@@ -479,7 +488,7 @@ func TestIgmpV1Present(t *testing.T) {
 	if ok {
 		t.Fatalf("sent unexpected packet, expected V1MembershipReport only after advancing the clock = %+v", p.Pkt)
 	}
-	clock.Advance(unsolicitedReportIntervalMax)
+	clock.Advance(ipv4.UnsolicitedReportIntervalMax)
 	p, ok = e.Read()
 	if !ok {
 		t.Fatal("unable to Read IGMP packet, expected V1MembershipReport")