Merge release-20201130.0-80-g53a95ad0d (automated)

6 files changed, 332 insertions, 49 deletions

diff --git a/pkg/tcpip/network/ip/generic_multicast_protocol.go b/pkg/tcpip/network/ip/generic_multicast_protocol.go
index c8c17ab15..f85c5ff9d 100644
--- a/pkg/tcpip/network/ip/generic_multicast_protocol.go
+++ b/pkg/tcpip/network/ip/generic_multicast_protocol.go
@@ -30,6 +30,23 @@ type hostState int
 // The states below are generic across IGMPv2 (RFC 2236 section 6) and MLDv1
 // (RFC 2710 section 5). Even though the states are generic across both IGMPv2
 // and MLDv1, IGMPv2 terminology will be used.
+//
+//                                  ______________receive query______________
+//                                 |                                         |
+//                                 |   _____send or receive report_____      |
+//                                 |  |                                |     |
+//                                 V  |                                V     |
+//  +-------+ +-----------+ +------------+ +-------------------+ +--------+  |
+//  | Non-M | | Pending-M | | Delaying-M | | Queued Delaying-M | | Idle-M | -
+//  +-------+ +-----------+ +------------+ +-------------------+ +--------+
+//    |          ^      |       ^      |          ^       |             ^
+//    |          |      |       |      |          |       |             |
+//     ----------        -------        ----------         -------------
+//   initialize new    send inital     fail to send       send or receive
+//  group membership     report       delayed report          report
+//
+// Not shown in the diagram above, but any state may transition into the non
+// member state when a group is left.
 const (
 	// nonMember is the "'Non-Member' state, when the host does not belong to the
 	// group on the interface. This is the initial state for all memberships on
@@ -41,6 +58,15 @@ const (
 	// but without advertising the membership to the network.
 	nonMember hostState = iota
 
+	// pendingMember is a newly joined member that is waiting to successfully send
+	// the initial set of reports.
+	//
+	// This is not an RFC defined state; it is an implementation specific state to
+	// track that the initial report needs to be sent.
+	//
+	// MAY NOT transition to the idle member state from this state.
+	pendingMember
+
 	// delayingMember is the "'Delaying Member' state, when the host belongs to
 	// the group on the interface and has a report delay timer running for that
 	// membership."
@@ -48,6 +74,16 @@ const (
 	// 'Delaying Listener' is the MLDv1 term used to describe this state.
 	delayingMember
 
+	// queuedDelayingMember is a delayingMember that failed to send a report after
+	// its delayed report timer fired. Hosts in this state are waiting to attempt
+	// retransmission of the delayed report.
+	//
+	// This is not an RFC defined state; it is an implementation specific state to
+	// track that the delayed report needs to be sent.
+	//
+	// May transition to idle member if a report is received for a group.
+	queuedDelayingMember
+
 	// idleMember is the "Idle Member" state, when the host belongs to the group
 	// on the interface and does not have a report delay timer running for that
 	// membership.
@@ -56,6 +92,17 @@ const (
 	idleMember
 )
 
+func (s hostState) isDelayingMember() bool {
+	switch s {
+	case nonMember, pendingMember, idleMember:
+		return false
+	case delayingMember, queuedDelayingMember:
+		return true
+	default:
+		panic(fmt.Sprintf("unrecognized host state = %d", s))
+	}
+}
+
 // multicastGroupState holds the Generic Multicast Protocol state for a
 // multicast group.
 type multicastGroupState struct {
@@ -124,7 +171,10 @@ type GenericMulticastProtocolOptions struct {
 // can be represented by GenericMulticastProtocolState.
 type MulticastGroupProtocol interface {
 	// SendReport sends a multicast report for the specified group address.
-	SendReport(groupAddress tcpip.Address) *tcpip.Error
+	//
+	// Returns false if the caller should queue the report to be sent later. Note,
+	// returning false does not mean that the receiver hit an error.
+	SendReport(groupAddress tcpip.Address) (sent bool, err *tcpip.Error)
 
 	// SendLeave sends a multicast leave for the specified group address.
 	SendLeave(groupAddress tcpip.Address) *tcpip.Error
@@ -166,6 +216,9 @@ type GenericMulticastProtocolState struct {
 //
 // The GenericMulticastProtocolState will only grab the lock when timers/jobs
 // fire.
+//
+// Note: the methods on opts.Protocol will always be called while protocolMU is
+// held.
 func (g *GenericMulticastProtocolState) Init(protocolMU *sync.RWMutex, opts GenericMulticastProtocolOptions) {
 	if g.memberships != nil {
 		panic("attempted to initialize generic membership protocol state twice")
@@ -212,6 +265,29 @@ func (g *GenericMulticastProtocolState) InitializeGroupsLocked() {
 	}
 }
 
+// SendQueuedReportsLocked attempts to send reports for groups that failed to
+// send reports during their last attempt.
+//
+// Precondition: g.protocolMU must be locked.
+func (g *GenericMulticastProtocolState) SendQueuedReportsLocked() {
+	for groupAddress, info := range g.memberships {
+		switch info.state {
+		case nonMember, delayingMember, idleMember:
+		case pendingMember:
+			// pendingMembers failed to send their initial unsolicited report so try
+			// to send the report and queue the extra unsolicited reports.
+			g.maybeSendInitialReportLocked(groupAddress, &info)
+		case queuedDelayingMember:
+			// queuedDelayingMembers failed to send their delayed reports so try to
+			// send the report and transition them to the idle state.
+			g.maybeSendDelayedReportLocked(groupAddress, &info)
+		default:
+			panic(fmt.Sprintf("unrecognized host state = %d", info.state))
+		}
+		g.memberships[groupAddress] = info
+	}
+}
+
 // JoinGroupLocked handles joining a new group.
 //
 // If dontInitialize is true, the group will be not be initialized and will be
@@ -239,8 +315,7 @@ func (g *GenericMulticastProtocolState) JoinGroupLocked(groupAddress tcpip.Addre
 				panic(fmt.Sprintf("expected to find group state for group = %s", groupAddress))
 			}
 
-			info.lastToSendReport = g.opts.Protocol.SendReport(groupAddress) == nil
-			info.state = idleMember
+			g.maybeSendDelayedReportLocked(groupAddress, &info)
 			g.memberships[groupAddress] = info
 		}),
 	}
@@ -347,7 +422,7 @@ func (g *GenericMulticastProtocolState) HandleReportLocked(groupAddress tcpip.Ad
 	//   multicast address while it has a timer running for that same address
 	//   on that interface, it stops its timer and does not send a Report for
 	//   that address, thus suppressing duplicate reports on the link.
-	if info, ok := g.memberships[groupAddress]; ok && info.state == delayingMember {
+	if info, ok := g.memberships[groupAddress]; ok && info.state.isDelayingMember() {
 		info.delayedReportJob.Cancel()
 		info.lastToSendReport = false
 		info.state = idleMember
@@ -360,10 +435,10 @@ func (g *GenericMulticastProtocolState) HandleReportLocked(groupAddress tcpip.Ad
 // Precondition: g.protocolMU must be locked.
 func (g *GenericMulticastProtocolState) initializeNewMemberLocked(groupAddress tcpip.Address, info *multicastGroupState) {
 	if info.state != nonMember {
-		panic(fmt.Sprintf("state for group %s is not non-member; state = %d", groupAddress, info.state))
+		panic(fmt.Sprintf("host must be in non-member state to be initialized; group = %s, state = %d", groupAddress, info.state))
 	}
 
-	info.state = idleMember
+	info.lastToSendReport = false
 
 	if groupAddress == g.opts.AllNodesAddress {
 		// As per RFC 2236 section 6 page 10 (for IGMPv2),
@@ -379,9 +454,25 @@ func (g *GenericMulticastProtocolState) initializeNewMemberLocked(groupAddress t
 		//   case. The node starts in Idle Listener state for that address on
 		//   every interface, never transitions to another state, and never sends
 		//   a Report or Done for that address.
+		info.state = idleMember
 		return
 	}
 
+	info.state = pendingMember
+	g.maybeSendInitialReportLocked(groupAddress, info)
+}
+
+// maybeSendInitialReportLocked attempts to start transmission of the initial
+// set of reports after newly joining a group.
+//
+// Host must be in pending member state.
+//
+// Precondition: g.protocolMU must be locked.
+func (g *GenericMulticastProtocolState) maybeSendInitialReportLocked(groupAddress tcpip.Address, info *multicastGroupState) {
+	if info.state != pendingMember {
+		panic(fmt.Sprintf("host must be in pending member state to send initial reports; group = %s, state = %d", groupAddress, info.state))
+	}
+
 	// As per RFC 2236 section 3 page 5 (for IGMPv2),
 	//
 	//   When a host joins a multicast group, it should immediately transmit an
@@ -399,8 +490,30 @@ func (g *GenericMulticastProtocolState) initializeNewMemberLocked(groupAddress t
 	//
 	// TODO(gvisor.dev/issue/4901): Support a configurable number of initial
 	// unsolicited reports.
-	info.lastToSendReport = g.opts.Protocol.SendReport(groupAddress) == nil
-	g.setDelayTimerForAddressRLocked(groupAddress, info, g.opts.MaxUnsolicitedReportDelay)
+	sent, err := g.opts.Protocol.SendReport(groupAddress)
+	if err == nil && sent {
+		info.lastToSendReport = true
+		g.setDelayTimerForAddressRLocked(groupAddress, info, g.opts.MaxUnsolicitedReportDelay)
+	}
+}
+
+// maybeSendDelayedReportLocked attempts to send the delayed report.
+//
+// Host must be in pending, delaying or queued delaying member state.
+//
+// Precondition: g.protocolMU must be locked.
+func (g *GenericMulticastProtocolState) maybeSendDelayedReportLocked(groupAddress tcpip.Address, info *multicastGroupState) {
+	if !info.state.isDelayingMember() {
+		panic(fmt.Sprintf("host must be in delaying or queued delaying member state to send delayed reports; group = %s, state = %d", groupAddress, info.state))
+	}
+
+	sent, err := g.opts.Protocol.SendReport(groupAddress)
+	if err == nil && sent {
+		info.lastToSendReport = true
+		info.state = idleMember
+	} else {
+		info.state = queuedDelayingMember
+	}
 }
 
 // maybeSendLeave attempts to send a leave message.
@@ -531,6 +644,7 @@ func (g *GenericMulticastProtocolState) setDelayTimerForAddressRLocked(groupAddr
 		// TODO: Reset the timer if time remaining is greater than maxResponseTime.
 		return
 	}
+
 	info.state = delayingMember
 	info.delayedReportJob.Cancel()
 	info.delayedReportJob.Schedule(g.calculateDelayTimerDuration(maxResponseTime))
diff --git a/pkg/tcpip/network/ipv4/igmp.go b/pkg/tcpip/network/ipv4/igmp.go
index a3a7176a0..fb7a9e68e 100644
--- a/pkg/tcpip/network/ipv4/igmp.go
+++ b/pkg/tcpip/network/ipv4/igmp.go
@@ -96,7 +96,9 @@ type igmpState struct {
 }
 
 // SendReport implements ip.MulticastGroupProtocol.
-func (igmp *igmpState) SendReport(groupAddress tcpip.Address) *tcpip.Error {
+//
+// Precondition: igmp.ep.mu must be read locked.
+func (igmp *igmpState) SendReport(groupAddress tcpip.Address) (bool, *tcpip.Error) {
 	igmpType := header.IGMPv2MembershipReport
 	if igmp.v1Present() {
 		igmpType = header.IGMPv1MembershipReport
@@ -105,6 +107,8 @@ func (igmp *igmpState) SendReport(groupAddress tcpip.Address) *tcpip.Error {
 }
 
 // SendLeave implements ip.MulticastGroupProtocol.
+//
+// Precondition: igmp.ep.mu must be read locked.
 func (igmp *igmpState) SendLeave(groupAddress tcpip.Address) *tcpip.Error {
 	// As per RFC 2236 Section 6, Page 8: "If the interface state says the
 	// Querier is running IGMPv1, this action SHOULD be skipped. If the flag
@@ -113,7 +117,8 @@ func (igmp *igmpState) SendLeave(groupAddress tcpip.Address) *tcpip.Error {
 	if igmp.v1Present() {
 		return nil
 	}
-	return igmp.writePacket(header.IPv4AllRoutersGroup, groupAddress, header.IGMPLeaveGroup)
+	_, err := igmp.writePacket(header.IPv4AllRoutersGroup, groupAddress, header.IGMPLeaveGroup)
+	return err
 }
 
 // init sets up an igmpState struct, and is required to be called before using
@@ -235,9 +240,10 @@ func (igmp *igmpState) handleMembershipReport(groupAddress tcpip.Address) {
 	igmp.genericMulticastProtocol.HandleReportLocked(groupAddress)
 }
 
-// writePacket assembles and sends an IGMP packet with the provided fields,
-// incrementing the provided stat counter on success.
-func (igmp *igmpState) writePacket(destAddress tcpip.Address, groupAddress tcpip.Address, igmpType header.IGMPType) *tcpip.Error {
+// writePacket assembles and sends an IGMP packet.
+//
+// Precondition: igmp.ep.mu must be read locked.
+func (igmp *igmpState) writePacket(destAddress tcpip.Address, groupAddress tcpip.Address, igmpType header.IGMPType) (bool, *tcpip.Error) {
 	igmpData := header.IGMP(buffer.NewView(header.IGMPReportMinimumSize))
 	igmpData.SetType(igmpType)
 	igmpData.SetGroupAddress(groupAddress)
@@ -248,9 +254,13 @@ func (igmp *igmpState) writePacket(destAddress tcpip.Address, groupAddress tcpip
 		Data:               buffer.View(igmpData).ToVectorisedView(),
 	})
 
-	// TODO(gvisor.dev/issue/4888): We should not use the unspecified address,
-	// rather we should select an appropriate local address.
-	localAddr := header.IPv4Any
+	addressEndpoint := igmp.ep.acquireOutgoingPrimaryAddressRLocked(destAddress, false /* allowExpired */)
+	if addressEndpoint == nil {
+		return false, nil
+	}
+	localAddr := addressEndpoint.AddressWithPrefix().Address
+	addressEndpoint.DecRef()
+	addressEndpoint = nil
 	igmp.ep.addIPHeader(localAddr, destAddress, pkt, stack.NetworkHeaderParams{
 		Protocol: header.IGMPProtocolNumber,
 		TTL:      header.IGMPTTL,
@@ -259,22 +269,22 @@ func (igmp *igmpState) writePacket(destAddress tcpip.Address, groupAddress tcpip
 		&header.IPv4SerializableRouterAlertOption{},
 	})
 
-	sent := igmp.ep.protocol.stack.Stats().IGMP.PacketsSent
+	sentStats := igmp.ep.protocol.stack.Stats().IGMP.PacketsSent
 	if err := igmp.ep.nic.WritePacketToRemote(header.EthernetAddressFromMulticastIPv4Address(destAddress), nil /* gso */, ProtocolNumber, pkt); err != nil {
-		sent.Dropped.Increment()
-		return err
+		sentStats.Dropped.Increment()
+		return false, err
 	}
 	switch igmpType {
 	case header.IGMPv1MembershipReport:
-		sent.V1MembershipReport.Increment()
+		sentStats.V1MembershipReport.Increment()
 	case header.IGMPv2MembershipReport:
-		sent.V2MembershipReport.Increment()
+		sentStats.V2MembershipReport.Increment()
 	case header.IGMPLeaveGroup:
-		sent.LeaveGroup.Increment()
+		sentStats.LeaveGroup.Increment()
 	default:
 		panic(fmt.Sprintf("unrecognized igmp type = %d", igmpType))
 	}
-	return nil
+	return true, nil
 }
 
 // joinGroup handles adding a new group to the membership map, setting up the
@@ -325,3 +335,10 @@ func (igmp *igmpState) softLeaveAll() {
 func (igmp *igmpState) initializeAll() {
 	igmp.genericMulticastProtocol.InitializeGroupsLocked()
 }
+
+// sendQueuedReports attempts to send any reports that are queued for sending.
+//
+// Precondition: igmp.ep.mu must be locked.
+func (igmp *igmpState) sendQueuedReports() {
+	igmp.genericMulticastProtocol.SendQueuedReportsLocked()
+}
diff --git a/pkg/tcpip/network/ipv4/ipv4.go b/pkg/tcpip/network/ipv4/ipv4.go
index c63ecca4a..e9ff70d04 100644
--- a/pkg/tcpip/network/ipv4/ipv4.go
+++ b/pkg/tcpip/network/ipv4/ipv4.go
@@ -172,7 +172,7 @@ func (e *endpoint) Disable() {
 }
 
 func (e *endpoint) disableLocked() {
-	if !e.setEnabled(false) {
+	if !e.isEnabled() {
 		return
 	}
 
@@ -189,6 +189,10 @@ func (e *endpoint) disableLocked() {
 	if err := e.mu.addressableEndpointState.RemovePermanentAddress(ipv4BroadcastAddr.Address); err != nil && err != tcpip.ErrBadLocalAddress {
 		panic(fmt.Sprintf("unexpected error when removing address = %s: %s", ipv4BroadcastAddr.Address, err))
 	}
+
+	if !e.setEnabled(false) {
+		panic("should have only done work to disable the endpoint if it was enabled")
+	}
 }
 
 // DefaultTTL is the default time-to-live value for this endpoint.
@@ -780,7 +784,12 @@ func (e *endpoint) Close() {
 func (e *endpoint) AddAndAcquirePermanentAddress(addr tcpip.AddressWithPrefix, peb stack.PrimaryEndpointBehavior, configType stack.AddressConfigType, deprecated bool) (stack.AddressEndpoint, *tcpip.Error) {
 	e.mu.Lock()
 	defer e.mu.Unlock()
-	return e.mu.addressableEndpointState.AddAndAcquirePermanentAddress(addr, peb, configType, deprecated)
+
+	ep, err := e.mu.addressableEndpointState.AddAndAcquirePermanentAddress(addr, peb, configType, deprecated)
+	if err == nil {
+		e.mu.igmp.sendQueuedReports()
+	}
+	return ep, err
 }
 
 // RemovePermanentAddress implements stack.AddressableEndpoint.
@@ -815,6 +824,14 @@ func (e *endpoint) AcquireAssignedAddress(localAddr tcpip.Address, allowTemp boo
 func (e *endpoint) AcquireOutgoingPrimaryAddress(remoteAddr tcpip.Address, allowExpired bool) stack.AddressEndpoint {
 	e.mu.RLock()
 	defer e.mu.RUnlock()
+	return e.acquireOutgoingPrimaryAddressRLocked(remoteAddr, allowExpired)
+}
+
+// acquireOutgoingPrimaryAddressRLocked is like AcquireOutgoingPrimaryAddress
+// but with locking requirements
+//
+// Precondition: igmp.ep.mu must be read locked.
+func (e *endpoint) acquireOutgoingPrimaryAddressRLocked(remoteAddr tcpip.Address, allowExpired bool) stack.AddressEndpoint {
 	return e.mu.addressableEndpointState.AcquireOutgoingPrimaryAddress(remoteAddr, allowExpired)
 }
 
diff --git a/pkg/tcpip/network/ipv6/ipv6.go b/pkg/tcpip/network/ipv6/ipv6.go
index 7288e309c..e506e99e9 100644
--- a/pkg/tcpip/network/ipv6/ipv6.go
+++ b/pkg/tcpip/network/ipv6/ipv6.go
@@ -121,6 +121,45 @@ type OpaqueInterfaceIdentifierOptions struct {
 	SecretKey []byte
 }
 
+// onAddressAssignedLocked handles an address being assigned.
+//
+// Precondition: e.mu must be exclusively locked.
+func (e *endpoint) onAddressAssignedLocked(addr tcpip.Address) {
+	// As per RFC 2710 section 3,
+	//
+	//   All MLD  messages described in this document are sent with a link-local
+	//   IPv6 Source Address, ...
+	//
+	// If we just completed DAD for a link-local address, then attempt to send any
+	// queued MLD reports. Note, we may have sent reports already for some of the
+	// groups before we had a valid link-local address to use as the source for
+	// the MLD messages, but that was only so that MLD snooping switches are aware
+	// of our membership to groups - routers would not have handled those reports.
+	//
+	// As per RFC 3590 section 4,
+	//
+	//   MLD Report and Done messages are sent with a link-local address as
+	//   the IPv6 source address, if a valid address is available on the
+	//   interface. If a valid link-local address is not available (e.g., one
+	//   has not been configured), the message is sent with the unspecified
+	//   address (::) as the IPv6 source address.
+	//
+	//   Once a valid link-local address is available, a node SHOULD generate
+	//   new MLD Report messages for all multicast addresses joined on the
+	//   interface.
+	//
+	//   Routers receiving an MLD Report or Done message with the unspecified
+	//   address as the IPv6 source address MUST silently discard the packet
+	//   without taking any action on the packets contents.
+	//
+	//   Snooping switches MUST manage multicast forwarding state based on MLD
+	//   Report and Done messages sent with the unspecified address as the
+	//   IPv6 source address.
+	if header.IsV6LinkLocalAddress(addr) {
+		e.mu.mld.sendQueuedReports()
+	}
+}
+
 // InvalidateDefaultRouter implements stack.NDPEndpoint.
 func (e *endpoint) InvalidateDefaultRouter(rtr tcpip.Address) {
 	e.mu.Lock()
@@ -333,7 +372,7 @@ func (e *endpoint) Disable() {
 }
 
 func (e *endpoint) disableLocked() {
-	if !e.setEnabled(false) {
+	if !e.Enabled() {
 		return
 	}
 
@@ -349,6 +388,10 @@ func (e *endpoint) disableLocked() {
 	// Leave groups from the perspective of MLD so that routers know that
 	// we are no longer interested in the group.
 	e.mu.mld.softLeaveAll()
+
+	if !e.setEnabled(false) {
+		panic("should have only done work to disable the endpoint if it was enabled")
+	}
 }
 
 // stopDADForPermanentAddressesLocked stops DAD for all permaneent addresses.
@@ -1176,13 +1219,6 @@ func (e *endpoint) addAndAcquirePermanentAddressLocked(addr tcpip.AddressWithPre
 		return addressEndpoint, nil
 	}
 
-	snmc := header.SolicitedNodeAddr(addr.Address)
-	if err := e.joinGroupLocked(snmc); err != nil {
-		// joinGroupLocked only returns an error if the group address is not a valid
-		// IPv6 multicast address.
-		panic(fmt.Sprintf("e.joinGroupLocked(%s): %s", snmc, err))
-	}
-
 	addressEndpoint.SetKind(stack.PermanentTentative)
 
 	if e.Enabled() {
@@ -1191,6 +1227,13 @@ func (e *endpoint) addAndAcquirePermanentAddressLocked(addr tcpip.AddressWithPre
 		}
 	}
 
+	snmc := header.SolicitedNodeAddr(addr.Address)
+	if err := e.joinGroupLocked(snmc); err != nil {
+		// joinGroupLocked only returns an error if the group address is not a valid
+		// IPv6 multicast address.
+		panic(fmt.Sprintf("e.joinGroupLocked(%s): %s", snmc, err))
+	}
+
 	return addressEndpoint, nil
 }
 
@@ -1292,6 +1335,26 @@ func (e *endpoint) AcquireOutgoingPrimaryAddress(remoteAddr tcpip.Address, allow
 	return e.acquireOutgoingPrimaryAddressRLocked(remoteAddr, allowExpired)
 }
 
+// getLinkLocalAddressRLocked returns a link-local address from the primary list
+// of addresses, if one is available.
+//
+// See stack.PrimaryEndpointBehavior for more details about the primary list.
+//
+// Precondition: e.mu must be read locked.
+func (e *endpoint) getLinkLocalAddressRLocked() tcpip.Address {
+	var linkLocalAddr tcpip.Address
+	e.mu.addressableEndpointState.ForEachPrimaryEndpoint(func(addressEndpoint stack.AddressEndpoint) bool {
+		if addressEndpoint.IsAssigned(false /* allowExpired */) {
+			if addr := addressEndpoint.AddressWithPrefix().Address; header.IsV6LinkLocalAddress(addr) {
+				linkLocalAddr = addr
+				return false
+			}
+		}
+		return true
+	})
+	return linkLocalAddr
+}
+
 // acquireOutgoingPrimaryAddressRLocked is like AcquireOutgoingPrimaryAddress
 // but with locking requirements.
 //
@@ -1311,10 +1374,10 @@ func (e *endpoint) acquireOutgoingPrimaryAddressRLocked(remoteAddr tcpip.Address
 	// Create a candidate set of available addresses we can potentially use as a
 	// source address.
 	var cs []addrCandidate
-	e.mu.addressableEndpointState.ForEachPrimaryEndpoint(func(addressEndpoint stack.AddressEndpoint) {
+	e.mu.addressableEndpointState.ForEachPrimaryEndpoint(func(addressEndpoint stack.AddressEndpoint) bool {
 		// If r is not valid for outgoing connections, it is not a valid endpoint.
 		if !addressEndpoint.IsAssigned(allowExpired) {
-			return
+			return true
 		}
 
 		addr := addressEndpoint.AddressWithPrefix().Address
@@ -1330,6 +1393,8 @@ func (e *endpoint) acquireOutgoingPrimaryAddressRLocked(remoteAddr tcpip.Address
 			addressEndpoint: addressEndpoint,
 			scope:           scope,
 		})
+
+		return true
 	})
 
 	remoteScope, err := header.ScopeForIPv6Address(remoteAddr)
diff --git a/pkg/tcpip/network/ipv6/mld.go b/pkg/tcpip/network/ipv6/mld.go
index b67eafdba..48644d9c8 100644
--- a/pkg/tcpip/network/ipv6/mld.go
+++ b/pkg/tcpip/network/ipv6/mld.go
@@ -59,13 +59,18 @@ type mldState struct {
 }
 
 // SendReport implements ip.MulticastGroupProtocol.
-func (mld *mldState) SendReport(groupAddress tcpip.Address) *tcpip.Error {
+//
+// Precondition: mld.ep.mu must be read locked.
+func (mld *mldState) SendReport(groupAddress tcpip.Address) (bool, *tcpip.Error) {
 	return mld.writePacket(groupAddress, groupAddress, header.ICMPv6MulticastListenerReport)
 }
 
 // SendLeave implements ip.MulticastGroupProtocol.
+//
+// Precondition: mld.ep.mu must be read locked.
 func (mld *mldState) SendLeave(groupAddress tcpip.Address) *tcpip.Error {
-	return mld.writePacket(header.IPv6AllRoutersMulticastAddress, groupAddress, header.ICMPv6MulticastListenerDone)
+	_, err := mld.writePacket(header.IPv6AllRoutersMulticastAddress, groupAddress, header.ICMPv6MulticastListenerDone)
+	return err
 }
 
 // init sets up an mldState struct, and is required to be called before using
@@ -147,7 +152,17 @@ func (mld *mldState) initializeAll() {
 	mld.genericMulticastProtocol.InitializeGroupsLocked()
 }
 
-func (mld *mldState) writePacket(destAddress, groupAddress tcpip.Address, mldType header.ICMPv6Type) *tcpip.Error {
+// sendQueuedReports attempts to send any reports that are queued for sending.
+//
+// Precondition: mld.ep.mu must be locked.
+func (mld *mldState) sendQueuedReports() {
+	mld.genericMulticastProtocol.SendQueuedReportsLocked()
+}
+
+// writePacket assembles and sends an MLD packet.
+//
+// Precondition: mld.ep.mu must be read locked.
+func (mld *mldState) writePacket(destAddress, groupAddress tcpip.Address, mldType header.ICMPv6Type) (bool, *tcpip.Error) {
 	sentStats := mld.ep.protocol.stack.Stats().ICMP.V6.PacketsSent
 	var mldStat *tcpip.StatCounter
 	switch mldType {
@@ -162,9 +177,61 @@ func (mld *mldState) writePacket(destAddress, groupAddress tcpip.Address, mldTyp
 	icmp := header.ICMPv6(buffer.NewView(header.ICMPv6HeaderSize + header.MLDMinimumSize))
 	icmp.SetType(mldType)
 	header.MLD(icmp.MessageBody()).SetMulticastAddress(groupAddress)
-	// TODO(gvisor.dev/issue/4888): We should not use the unspecified address,
-	// rather we should select an appropriate local address.
-	localAddress := header.IPv6Any
+	// As per RFC 2710 section 3,
+	//
+	//   All MLD messages described in this document are sent with a link-local
+	//   IPv6 Source Address, an IPv6 Hop Limit of 1, and an IPv6 Router Alert
+	//   option in a Hop-by-Hop Options header.
+	//
+	// However, this would cause problems with Duplicate Address Detection with
+	// the first address as MLD snooping switches may not send multicast traffic
+	// that DAD depends on to the node performing DAD without the MLD report, as
+	// documented in RFC 4816:
+	//
+	//   Note that when a node joins a multicast address, it typically sends a
+	//   Multicast Listener Discovery (MLD) report message [RFC2710] [RFC3810]
+	//   for the multicast address. In the case of Duplicate Address
+	//   Detection, the MLD report message is required in order to inform MLD-
+	//   snooping switches, rather than routers, to forward multicast packets.
+	//   In the above description, the delay for joining the multicast address
+	//   thus means delaying transmission of the corresponding MLD report
+	//   message. Since the MLD specifications do not request a random delay
+	//   to avoid race conditions, just delaying Neighbor Solicitation would
+	//   cause congestion by the MLD report messages. The congestion would
+	//   then prevent the MLD-snooping switches from working correctly and, as
+	//   a result, prevent Duplicate Address Detection from working. The
+	//   requirement to include the delay for the MLD report in this case
+	//   avoids this scenario. [RFC3590] also talks about some interaction
+	//   issues between Duplicate Address Detection and MLD, and specifies
+	//   which source address should be used for the MLD report in this case.
+	//
+	// As per RFC 3590 section 4, we should still send out MLD reports with an
+	// unspecified source address if we do not have an assigned link-local
+	// address to use as the source address to ensure DAD works as expected on
+	// networks with MLD snooping switches:
+	//
+	//   MLD Report and Done messages are sent with a link-local address as
+	//   the IPv6 source address, if a valid address is available on the
+	//   interface.  If a valid link-local address is not available (e.g., one
+	//   has not been configured), the message is sent with the unspecified
+	//   address (::) as the IPv6 source address.
+	//
+	//   Once a valid link-local address is available, a node SHOULD generate
+	//   new MLD Report messages for all multicast addresses joined on the
+	//   interface.
+	//
+	//   Routers receiving an MLD Report or Done message with the unspecified
+	//   address as the IPv6 source address MUST silently discard the packet
+	//   without taking any action on the packets contents.
+	//
+	//   Snooping switches MUST manage multicast forwarding state based on MLD
+	//   Report and Done messages sent with the unspecified address as the
+	//   IPv6 source address.
+	localAddress := mld.ep.getLinkLocalAddressRLocked()
+	if len(localAddress) == 0 {
+		localAddress = header.IPv6Any
+	}
+
 	icmp.SetChecksum(header.ICMPv6Checksum(icmp, localAddress, destAddress, buffer.VectorisedView{}))
 
 	pkt := stack.NewPacketBuffer(stack.PacketBufferOptions{
@@ -180,8 +247,8 @@ func (mld *mldState) writePacket(destAddress, groupAddress tcpip.Address, mldTyp
 	// Membership Reports.
 	if err := mld.ep.nic.WritePacketToRemote(header.EthernetAddressFromMulticastIPv6Address(destAddress), nil /* gso */, ProtocolNumber, pkt); err != nil {
 		sentStats.Dropped.Increment()
-		return err
+		return false, err
 	}
 	mldStat.Increment()
-	return nil
+	return localAddress != header.IPv6Any, nil
 }
diff --git a/pkg/tcpip/network/ipv6/ndp.go b/pkg/tcpip/network/ipv6/ndp.go
index 2f5e2e82c..3b892aeda 100644
--- a/pkg/tcpip/network/ipv6/ndp.go
+++ b/pkg/tcpip/network/ipv6/ndp.go
@@ -647,6 +647,7 @@ func (ndp *ndpState) startDuplicateAddressDetection(addr tcpip.Address, addressE
 			ndpDisp.OnDuplicateAddressDetectionStatus(ndp.ep.nic.ID(), addr, true, nil)
 		}
 
+		ndp.ep.onAddressAssignedLocked(addr)
 		return nil
 	}
 
@@ -690,12 +691,14 @@ func (ndp *ndpState) startDuplicateAddressDetection(addr tcpip.Address, addressE
 				ndpDisp.OnDuplicateAddressDetectionStatus(ndp.ep.nic.ID(), addr, dadDone, err)
 			}
 
-			// If DAD resolved for a stable SLAAC address, attempt generation of a
-			// temporary SLAAC address.
-			if dadDone && addressEndpoint.ConfigType() == stack.AddressConfigSlaac {
-				// Reset the generation attempts counter as we are starting the generation
-				// of a new address for the SLAAC prefix.
-				ndp.regenerateTempSLAACAddr(addressEndpoint.AddressWithPrefix().Subnet(), true /* resetGenAttempts */)
+			if dadDone {
+				if addressEndpoint.ConfigType() == stack.AddressConfigSlaac {
+					// Reset the generation attempts counter as we are starting the
+					// generation of a new address for the SLAAC prefix.
+					ndp.regenerateTempSLAACAddr(addressEndpoint.AddressWithPrefix().Subnet(), true /* resetGenAttempts */)
+				}
+
+				ndp.ep.onAddressAssignedLocked(addr)
 			}
 		}),
 	}