Do not perform MLD for certain multicast scopes

...as per RFC 2710 section 5 page 10.

Test: ipv6_test.TestMLDSkipProtocol
PiperOrigin-RevId: 367031126

7 files changed, 313 insertions, 70 deletions

diff --git a/pkg/tcpip/header/ipv6.go b/pkg/tcpip/header/ipv6.go
index f2403978c..7711abec1 100644
--- a/pkg/tcpip/header/ipv6.go
+++ b/pkg/tcpip/header/ipv6.go
@@ -142,11 +142,6 @@ const (
 	// ipv6MulticastAddressScopeMask is the mask for the scope (scop) field,
 	// within the byte holding the field, as per RFC 4291 section 2.7.
 	ipv6MulticastAddressScopeMask = 0xF
-
-	// ipv6LinkLocalMulticastScope is the value of the scope (scop) field within
-	// a multicast IPv6 address that indicates the address has link-local scope,
-	// as per RFC 4291 section 2.7.
-	ipv6LinkLocalMulticastScope = 2
 )
 
 // IPv6EmptySubnet is the empty IPv6 subnet. It may also be known as the
@@ -399,7 +394,7 @@ func IsV6LoopbackAddress(addr tcpip.Address) bool {
 // IsV6LinkLocalMulticastAddress determines if the provided address is an IPv6
 // link-local multicast address.
 func IsV6LinkLocalMulticastAddress(addr tcpip.Address) bool {
-	return IsV6MulticastAddress(addr) && addr[ipv6MulticastAddressScopeByteIdx]&ipv6MulticastAddressScopeMask == ipv6LinkLocalMulticastScope
+	return IsV6MulticastAddress(addr) && V6MulticastScope(addr) == IPv6LinkLocalMulticastScope
 }
 
 // AppendOpaqueInterfaceIdentifier appends a 64 bit opaque interface identifier
@@ -520,3 +515,45 @@ func GenerateTempIPv6SLAACAddr(tempIIDHistory []byte, stableAddr tcpip.Address)
 		PrefixLen: IIDOffsetInIPv6Address * 8,
 	}
 }
+
+// IPv6MulticastScope is the scope of a multicast IPv6 address.
+type IPv6MulticastScope uint8
+
+// The various values for IPv6 multicast scopes, as per RFC 7346 section 2:
+//
+//      +------+--------------------------+-------------------------+
+//      | scop | NAME                     | REFERENCE               |
+//      +------+--------------------------+-------------------------+
+//      |  0   | Reserved                 | [RFC4291], RFC 7346     |
+//      |  1   | Interface-Local scope    | [RFC4291], RFC 7346     |
+//      |  2   | Link-Local scope         | [RFC4291], RFC 7346     |
+//      |  3   | Realm-Local scope        | [RFC4291], RFC 7346     |
+//      |  4   | Admin-Local scope        | [RFC4291], RFC 7346     |
+//      |  5   | Site-Local scope         | [RFC4291], RFC 7346     |
+//      |  6   | Unassigned               |                         |
+//      |  7   | Unassigned               |                         |
+//      |  8   | Organization-Local scope | [RFC4291], RFC 7346     |
+//      |  9   | Unassigned               |                         |
+//      |  A   | Unassigned               |                         |
+//      |  B   | Unassigned               |                         |
+//      |  C   | Unassigned               |                         |
+//      |  D   | Unassigned               |                         |
+//      |  E   | Global scope             | [RFC4291], RFC 7346     |
+//      |  F   | Reserved                 | [RFC4291], RFC 7346     |
+//      +------+--------------------------+-------------------------+
+const (
+	IPv6Reserved0MulticastScope         = IPv6MulticastScope(0x0)
+	IPv6InterfaceLocalMulticastScope    = IPv6MulticastScope(0x1)
+	IPv6LinkLocalMulticastScope         = IPv6MulticastScope(0x2)
+	IPv6RealmLocalMulticastScope        = IPv6MulticastScope(0x3)
+	IPv6AdminLocalMulticastScope        = IPv6MulticastScope(0x4)
+	IPv6SiteLocalMulticastScope         = IPv6MulticastScope(0x5)
+	IPv6OrganizationLocalMulticastScope = IPv6MulticastScope(0x8)
+	IPv6GlobalMulticastScope            = IPv6MulticastScope(0xE)
+	IPv6ReservedFMulticastScope         = IPv6MulticastScope(0xF)
+)
+
+// V6MulticastScope returns the scope of a multicast address.
+func V6MulticastScope(addr tcpip.Address) IPv6MulticastScope {
+	return IPv6MulticastScope(addr[ipv6MulticastAddressScopeByteIdx] & ipv6MulticastAddressScopeMask)
+}
diff --git a/pkg/tcpip/header/ipv6_test.go b/pkg/tcpip/header/ipv6_test.go
index f10f446a6..38b6dbc18 100644
--- a/pkg/tcpip/header/ipv6_test.go
+++ b/pkg/tcpip/header/ipv6_test.go
@@ -373,3 +373,83 @@ func TestSolicitedNodeAddr(t *testing.T) {
 		})
 	}
 }
+
+func TestV6MulticastScope(t *testing.T) {
+	tests := []struct {
+		addr tcpip.Address
+		want header.IPv6MulticastScope
+	}{
+		{
+			addr: "\xff\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x01",
+			want: header.IPv6Reserved0MulticastScope,
+		},
+		{
+			addr: "\xff\x01\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x01",
+			want: header.IPv6InterfaceLocalMulticastScope,
+		},
+		{
+			addr: "\xff\x02\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x01",
+			want: header.IPv6LinkLocalMulticastScope,
+		},
+		{
+			addr: "\xff\x03\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x01",
+			want: header.IPv6RealmLocalMulticastScope,
+		},
+		{
+			addr: "\xff\x04\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x01",
+			want: header.IPv6AdminLocalMulticastScope,
+		},
+		{
+			addr: "\xff\x05\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x01",
+			want: header.IPv6SiteLocalMulticastScope,
+		},
+		{
+			addr: "\xff\x06\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x01",
+			want: header.IPv6MulticastScope(6),
+		},
+		{
+			addr: "\xff\x07\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x01",
+			want: header.IPv6MulticastScope(7),
+		},
+		{
+			addr: "\xff\x08\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x01",
+			want: header.IPv6OrganizationLocalMulticastScope,
+		},
+		{
+			addr: "\xff\x09\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x01",
+			want: header.IPv6MulticastScope(9),
+		},
+		{
+			addr: "\xff\x0a\x02\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x01",
+			want: header.IPv6MulticastScope(10),
+		},
+		{
+			addr: "\xff\x0b\x03\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x01",
+			want: header.IPv6MulticastScope(11),
+		},
+		{
+			addr: "\xff\x0c\x04\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x01",
+			want: header.IPv6MulticastScope(12),
+		},
+		{
+			addr: "\xff\x0d\x05\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x01",
+			want: header.IPv6MulticastScope(13),
+		},
+		{
+			addr: "\xff\x0e\x06\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x01",
+			want: header.IPv6GlobalMulticastScope,
+		},
+		{
+			addr: "\xff\x0f\x06\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x01",
+			want: header.IPv6ReservedFMulticastScope,
+		},
+	}
+
+	for _, test := range tests {
+		t.Run(fmt.Sprintf("%s", test.addr), func(t *testing.T) {
+			if got := header.V6MulticastScope(test.addr); got != test.want {
+				t.Fatalf("got header.V6MulticastScope(%s) = %d, want = %d", test.addr, got, test.want)
+			}
+		})
+	}
+}
diff --git a/pkg/tcpip/network/internal/ip/generic_multicast_protocol.go b/pkg/tcpip/network/internal/ip/generic_multicast_protocol.go
index b9f129728..ac35d81e7 100644
--- a/pkg/tcpip/network/internal/ip/generic_multicast_protocol.go
+++ b/pkg/tcpip/network/internal/ip/generic_multicast_protocol.go
@@ -156,14 +156,6 @@ type GenericMulticastProtocolOptions struct {
 	//
 	// Unsolicited reports are transmitted when a group is newly joined.
 	MaxUnsolicitedReportDelay time.Duration
-
-	// AllNodesAddress is a multicast address that all nodes on a network should
-	// be a member of.
-	//
-	// This address will not have the generic multicast protocol performed on it;
-	// it will be left in the non member/listener state, and packets will never
-	// be sent for it.
-	AllNodesAddress tcpip.Address
 }
 
 // MulticastGroupProtocol is a multicast group protocol whose core state machine
@@ -188,6 +180,10 @@ type MulticastGroupProtocol interface {
 
 	// SendLeave sends a multicast leave for the specified group address.
 	SendLeave(groupAddress tcpip.Address) tcpip.Error
+
+	// ShouldPerformProtocol returns true iff the protocol should be performed for
+	// the specified group.
+	ShouldPerformProtocol(tcpip.Address) bool
 }
 
 // GenericMulticastProtocolState is the per interface generic multicast protocol
@@ -455,20 +451,7 @@ func (g *GenericMulticastProtocolState) initializeNewMemberLocked(groupAddress t
 
 	info.lastToSendReport = false
 
-	if groupAddress == g.opts.AllNodesAddress {
-		// As per RFC 2236 section 6 page 10 (for IGMPv2),
-		//
-		//   The all-systems group (address 224.0.0.1) is handled as a special
-		//   case. The host starts in Idle Member state for that group on every
-		//   interface, never transitions to another state, and never sends a
-		//   report for that group.
-		//
-		// As per RFC 2710 section 5 page 10 (for MLDv1),
-		//
-		//   The link-scope all-nodes address (FF02::1) is handled as a special
-		//   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.
+	if !g.opts.Protocol.ShouldPerformProtocol(groupAddress) {
 		info.state = idleMember
 		return
 	}
@@ -537,20 +520,7 @@ func (g *GenericMulticastProtocolState) maybeSendLeave(groupAddress tcpip.Addres
 		return
 	}
 
-	if groupAddress == g.opts.AllNodesAddress {
-		// As per RFC 2236 section 6 page 10 (for IGMPv2),
-		//
-		//   The all-systems group (address 224.0.0.1) is handled as a special
-		//   case. The host starts in Idle Member state for that group on every
-		//   interface, never transitions to another state, and never sends a
-		//   report for that group.
-		//
-		// As per RFC 2710 section 5 page 10 (for MLDv1),
-		//
-		//   The link-scope all-nodes address (FF02::1) is handled as a special
-		//   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.
+	if !g.opts.Protocol.ShouldPerformProtocol(groupAddress) {
 		return
 	}
 
@@ -627,20 +597,7 @@ func (g *GenericMulticastProtocolState) setDelayTimerForAddressRLocked(groupAddr
 		return
 	}
 
-	if groupAddress == g.opts.AllNodesAddress {
-		// As per RFC 2236 section 6 page 10 (for IGMPv2),
-		//
-		//   The all-systems group (address 224.0.0.1) is handled as a special
-		//   case. The host starts in Idle Member state for that group on every
-		//   interface, never transitions to another state, and never sends a
-		//   report for that group.
-		//
-		// As per RFC 2710 section 5 page 10 (for MLDv1),
-		//
-		//   The link-scope all-nodes address (FF02::1) is handled as a special
-		//   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.
+	if !g.opts.Protocol.ShouldPerformProtocol(groupAddress) {
 		return
 	}
 
diff --git a/pkg/tcpip/network/internal/ip/generic_multicast_protocol_test.go b/pkg/tcpip/network/internal/ip/generic_multicast_protocol_test.go
index 381460c82..0b51563cd 100644
--- a/pkg/tcpip/network/internal/ip/generic_multicast_protocol_test.go
+++ b/pkg/tcpip/network/internal/ip/generic_multicast_protocol_test.go
@@ -43,6 +43,8 @@ type mockMulticastGroupProtocolProtectedFields struct {
 type mockMulticastGroupProtocol struct {
 	t *testing.T
 
+	skipProtocolAddress tcpip.Address
+
 	mu mockMulticastGroupProtocolProtectedFields
 }
 
@@ -165,6 +167,11 @@ func (m *mockMulticastGroupProtocol) SendLeave(groupAddress tcpip.Address) tcpip
 	return nil
 }
 
+// ShouldPerformProtocol implements ip.MulticastGroupProtocol.
+func (m *mockMulticastGroupProtocol) ShouldPerformProtocol(groupAddress tcpip.Address) bool {
+	return groupAddress != m.skipProtocolAddress
+}
+
 func (m *mockMulticastGroupProtocol) check(sendReportGroupAddresses []tcpip.Address, sendLeaveGroupAddresses []tcpip.Address) string {
 	m.mu.Lock()
 	defer m.mu.Unlock()
@@ -193,10 +200,11 @@ func (m *mockMulticastGroupProtocol) check(sendReportGroupAddresses []tcpip.Addr
 		cmp.FilterPath(
 			func(p cmp.Path) bool {
 				switch p.Last().String() {
-				case ".RWMutex", ".t", ".makeQueuePackets", ".disabled", ".genericMulticastGroup":
+				case ".RWMutex", ".t", ".makeQueuePackets", ".disabled", ".genericMulticastGroup", ".skipProtocolAddress":
 					return true
+				default:
+					return false
 				}
-				return false
 			},
 			cmp.Ignore(),
 		),
@@ -225,14 +233,13 @@ func TestJoinGroup(t *testing.T) {
 
 	for _, test := range tests {
 		t.Run(test.name, func(t *testing.T) {
-			mgp := mockMulticastGroupProtocol{t: t}
+			mgp := mockMulticastGroupProtocol{t: t, skipProtocolAddress: addr2}
 			clock := faketime.NewManualClock()
 
 			mgp.init(ip.GenericMulticastProtocolOptions{
 				Rand:                      rand.New(rand.NewSource(0)),
 				Clock:                     clock,
 				MaxUnsolicitedReportDelay: maxUnsolicitedReportDelay,
-				AllNodesAddress:           addr2,
 			})
 
 			// Joining a group should send a report immediately and another after
@@ -279,14 +286,13 @@ func TestLeaveGroup(t *testing.T) {
 
 	for _, test := range tests {
 		t.Run(test.name, func(t *testing.T) {
-			mgp := mockMulticastGroupProtocol{t: t}
+			mgp := mockMulticastGroupProtocol{t: t, skipProtocolAddress: addr2}
 			clock := faketime.NewManualClock()
 
 			mgp.init(ip.GenericMulticastProtocolOptions{
 				Rand:                      rand.New(rand.NewSource(1)),
 				Clock:                     clock,
 				MaxUnsolicitedReportDelay: maxUnsolicitedReportDelay,
-				AllNodesAddress:           addr2,
 			})
 
 			mgp.joinGroup(test.addr)
@@ -356,14 +362,13 @@ func TestHandleReport(t *testing.T) {
 
 	for _, test := range tests {
 		t.Run(test.name, func(t *testing.T) {
-			mgp := mockMulticastGroupProtocol{t: t}
+			mgp := mockMulticastGroupProtocol{t: t, skipProtocolAddress: addr3}
 			clock := faketime.NewManualClock()
 
 			mgp.init(ip.GenericMulticastProtocolOptions{
 				Rand:                      rand.New(rand.NewSource(2)),
 				Clock:                     clock,
 				MaxUnsolicitedReportDelay: maxUnsolicitedReportDelay,
-				AllNodesAddress:           addr3,
 			})
 
 			mgp.joinGroup(addr1)
@@ -446,14 +451,13 @@ func TestHandleQuery(t *testing.T) {
 
 	for _, test := range tests {
 		t.Run(test.name, func(t *testing.T) {
-			mgp := mockMulticastGroupProtocol{t: t}
+			mgp := mockMulticastGroupProtocol{t: t, skipProtocolAddress: addr3}
 			clock := faketime.NewManualClock()
 
 			mgp.init(ip.GenericMulticastProtocolOptions{
 				Rand:                      rand.New(rand.NewSource(3)),
 				Clock:                     clock,
 				MaxUnsolicitedReportDelay: maxUnsolicitedReportDelay,
-				AllNodesAddress:           addr3,
 			})
 
 			mgp.joinGroup(addr1)
@@ -574,14 +578,13 @@ func TestJoinCount(t *testing.T) {
 }
 
 func TestMakeAllNonMemberAndInitialize(t *testing.T) {
-	mgp := mockMulticastGroupProtocol{t: t}
+	mgp := mockMulticastGroupProtocol{t: t, skipProtocolAddress: addr3}
 	clock := faketime.NewManualClock()
 
 	mgp.init(ip.GenericMulticastProtocolOptions{
 		Rand:                      rand.New(rand.NewSource(3)),
 		Clock:                     clock,
 		MaxUnsolicitedReportDelay: maxUnsolicitedReportDelay,
-		AllNodesAddress:           addr3,
 	})
 
 	mgp.joinGroup(addr1)
diff --git a/pkg/tcpip/network/ipv4/igmp.go b/pkg/tcpip/network/ipv4/igmp.go
index f3fc1c87e..b1ac29294 100644
--- a/pkg/tcpip/network/ipv4/igmp.go
+++ b/pkg/tcpip/network/ipv4/igmp.go
@@ -126,6 +126,17 @@ func (igmp *igmpState) SendLeave(groupAddress tcpip.Address) tcpip.Error {
 	return err
 }
 
+// ShouldPerformProtocol implements ip.MulticastGroupProtocol.
+func (igmp *igmpState) ShouldPerformProtocol(groupAddress tcpip.Address) bool {
+	// As per RFC 2236 section 6 page 10,
+	//
+	//   The all-systems group (address 224.0.0.1) is handled as a special
+	//   case. The host starts in Idle Member state for that group on every
+	//   interface, never transitions to another state, and never sends a
+	//   report for that group.
+	return groupAddress != header.IPv4AllSystems
+}
+
 // init sets up an igmpState struct, and is required to be called before using
 // a new igmpState.
 //
@@ -137,7 +148,6 @@ func (igmp *igmpState) init(ep *endpoint) {
 		Clock:                     ep.protocol.stack.Clock(),
 		Protocol:                  igmp,
 		MaxUnsolicitedReportDelay: UnsolicitedReportIntervalMax,
-		AllNodesAddress:           header.IPv4AllSystems,
 	})
 	igmp.igmpV1Present = igmpV1PresentDefault
 	igmp.igmpV1Job = ep.protocol.stack.NewJob(&ep.mu, func() {
diff --git a/pkg/tcpip/network/ipv6/mld.go b/pkg/tcpip/network/ipv6/mld.go
index dd153466d..538590baf 100644
--- a/pkg/tcpip/network/ipv6/mld.go
+++ b/pkg/tcpip/network/ipv6/mld.go
@@ -80,6 +80,25 @@ func (mld *mldState) SendLeave(groupAddress tcpip.Address) tcpip.Error {
 	return err
 }
 
+// ShouldPerformProtocol implements ip.MulticastGroupProtocol.
+func (mld *mldState) ShouldPerformProtocol(groupAddress tcpip.Address) bool {
+	// As per RFC 2710 section 5 page 10,
+	//
+	//   The link-scope all-nodes address (FF02::1) is handled as a special
+	//   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.
+	//
+	//   MLD messages are never sent for multicast addresses whose scope is 0
+	//   (reserved) or 1 (node-local).
+	if groupAddress == header.IPv6AllNodesMulticastAddress {
+		return false
+	}
+
+	scope := header.V6MulticastScope(groupAddress)
+	return scope != header.IPv6Reserved0MulticastScope && scope != header.IPv6InterfaceLocalMulticastScope
+}
+
 // init sets up an mldState struct, and is required to be called before using
 // a new mldState.
 //
@@ -91,7 +110,6 @@ func (mld *mldState) init(ep *endpoint) {
 		Clock:                     ep.protocol.stack.Clock(),
 		Protocol:                  mld,
 		MaxUnsolicitedReportDelay: UnsolicitedReportIntervalMax,
-		AllNodesAddress:           header.IPv6AllNodesMulticastAddress,
 	})
 }
 
diff --git a/pkg/tcpip/network/ipv6/mld_test.go b/pkg/tcpip/network/ipv6/mld_test.go
index 85a8f9944..1e611aca1 100644
--- a/pkg/tcpip/network/ipv6/mld_test.go
+++ b/pkg/tcpip/network/ipv6/mld_test.go
@@ -464,3 +464,141 @@ func TestMLDPacketValidation(t *testing.T) {
 		})
 	}
 }
+
+func TestMLDSkipProtocol(t *testing.T) {
+	const nicID = 1
+
+	tests := []struct {
+		name         string
+		group        tcpip.Address
+		expectReport bool
+	}{
+		{
+			name:         "Reserverd0",
+			group:        "\xff\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x11",
+			expectReport: false,
+		},
+		{
+			name:         "Interface Local",
+			group:        "\xff\x01\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x11",
+			expectReport: false,
+		},
+		{
+			name:         "Link Local",
+			group:        "\xff\x02\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x11",
+			expectReport: true,
+		},
+		{
+			name:         "Realm Local",
+			group:        "\xff\x03\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x11",
+			expectReport: true,
+		},
+		{
+			name:         "Admin Local",
+			group:        "\xff\x04\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x11",
+			expectReport: true,
+		},
+		{
+			name:         "Site Local",
+			group:        "\xff\x05\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x11",
+			expectReport: true,
+		},
+		{
+			name:         "Unassigned(6)",
+			group:        "\xff\x06\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x11",
+			expectReport: true,
+		},
+		{
+			name:         "Unassigned(7)",
+			group:        "\xff\x07\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x11",
+			expectReport: true,
+		},
+		{
+			name:         "Organization Local",
+			group:        "\xff\x08\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x11",
+			expectReport: true,
+		},
+		{
+			name:         "Unassigned(9)",
+			group:        "\xff\x09\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x11",
+			expectReport: true,
+		},
+		{
+			name:         "Unassigned(A)",
+			group:        "\xff\x0a\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x11",
+			expectReport: true,
+		},
+		{
+			name:         "Unassigned(B)",
+			group:        "\xff\x0b\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x11",
+			expectReport: true,
+		},
+		{
+			name:         "Unassigned(C)",
+			group:        "\xff\x0c\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x11",
+			expectReport: true,
+		},
+		{
+			name:         "Unassigned(D)",
+			group:        "\xff\x0d\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x11",
+			expectReport: true,
+		},
+		{
+			name:         "Global",
+			group:        "\xff\x0e\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x11",
+			expectReport: true,
+		},
+		{
+			name:         "ReservedF",
+			group:        "\xff\x0f\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x11",
+			expectReport: true,
+		},
+	}
+
+	for _, test := range tests {
+		t.Run(test.name, func(t *testing.T) {
+			s := stack.New(stack.Options{
+				NetworkProtocols: []stack.NetworkProtocolFactory{ipv6.NewProtocolWithOptions(ipv6.Options{
+					MLD: ipv6.MLDOptions{
+						Enabled: true,
+					},
+				})},
+			})
+			e := channel.New(1, header.IPv6MinimumMTU, "")
+			if err := s.CreateNIC(nicID, e); err != nil {
+				t.Fatalf("CreateNIC(%d, _): %s", nicID, err)
+			}
+			if err := s.AddAddress(nicID, ipv6.ProtocolNumber, linkLocalAddr); err != nil {
+				t.Fatalf("AddAddress(%d, %d, %s) = %s", nicID, ipv6.ProtocolNumber, linkLocalAddr, err)
+			}
+			if p, ok := e.Read(); !ok {
+				t.Fatal("expected a report message to be sent")
+			} else {
+				validateMLDPacket(t, stack.PayloadSince(p.Pkt.NetworkHeader()), linkLocalAddr, linkLocalAddrSNMC, header.ICMPv6MulticastListenerReport, linkLocalAddrSNMC)
+			}
+
+			if err := s.JoinGroup(ipv6.ProtocolNumber, nicID, test.group); err != nil {
+				t.Fatalf("s.JoinGroup(%d, %d, %s): %s", ipv6.ProtocolNumber, nicID, test.group, err)
+			}
+			if isInGroup, err := s.IsInGroup(nicID, test.group); err != nil {
+				t.Fatalf("IsInGroup(%d, %s): %s", nicID, test.group, err)
+			} else if !isInGroup {
+				t.Fatalf("got IsInGroup(%d, %s) = false, want = true", nicID, test.group)
+			}
+
+			if !test.expectReport {
+				if p, ok := e.Read(); ok {
+					t.Fatalf("got e.Read() = (%#v, true), want = (_, false)", p)
+				}
+
+				return
+			}
+
+			if p, ok := e.Read(); !ok {
+				t.Fatal("expected a report message to be sent")
+			} else {
+				validateMLDPacket(t, stack.PayloadSince(p.Pkt.NetworkHeader()), linkLocalAddr, test.group, header.ICMPv6MulticastListenerReport, test.group)
+			}
+		})
+	}
+}