From d7fd00bad1416fb44b3303331ee223c28c69fe9b Mon Sep 17 00:00:00 2001 From: Ghanan Gowripalan Date: Tue, 6 Apr 2021 10:14:10 -0700 Subject: [PATCH] Do not perform MLD for certain multicast scopes ...as per RFC 2710 section 5 page 10. Test: ipv6_test.TestMLDSkipProtocol PiperOrigin-RevId: 367031126 --- pkg/tcpip/header/ipv6.go | 49 ++++++- pkg/tcpip/header/ipv6_test.go | 80 ++++++++++ .../internal/ip/generic_multicast_protocol.go | 57 +------- .../ip/generic_multicast_protocol_test.go | 27 ++-- pkg/tcpip/network/ipv4/igmp.go | 12 +- pkg/tcpip/network/ipv6/mld.go | 20 ++- pkg/tcpip/network/ipv6/mld_test.go | 138 ++++++++++++++++++ 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) + } + }) + } +}