ipv6: join the solicited-node multicast group of every assigned address

src/inet/networklayer/icmpv6/Ipv6NeighbourDiscovery.cc

@@ -846,8 +846,10 @@ void Ipv6NeighbourDiscovery::initiateDad(const Ipv6Address& tentativeAddr, Netwo
     msg->setContextPointer(dadEntry);
     dadEntry->timeoutMsg = msg;
 
-    // added uniform(0, IPv6_MAX_RTR_SOLICITATION_DELAY) to account for joining the solicited-node multicast
-    // group which is delay up to one 1 second (RFC 4862, 5.4.2)
+    // TODO the uniform(0, IPv6_MAX_RTR_SOLICITATION_DELAY) term was meant for the RFC 4862
+    // Section 5.4.2 delay before joining the solicited-node group, but it is added to the
+    // timeout -- the wait for an answer -- instead of delaying the first probe. The group
+    // itself is now joined when the address is assigned. See issue #1179.
     scheduleAfter(ie->getProtocolData<Ipv6InterfaceData>()->getRetransTimer() + uniform(0, IPv6_MAX_RTR_SOLICITATION_DELAY), msg);
 
     emit(startDadSignal, 1);

src/inet/networklayer/ipv6/Ipv6InterfaceData.cc

@@ -312,6 +312,11 @@ void Ipv6InterfaceData::assignAddress(const Ipv6Address& addr, bool tentative,
         Ipv6AddressInfo info(ownerp, addr);
         m->emit(ipv6AddressAssignedSignal, &info);
     }
+
+    // choosePreferredAddress() above drops an address whose valid lifetime has already
+    // run out, and leaves its group again; join only for one that is still held.
+    if (findAddress(addr) != -1)
+        joinSolicitedNodeMulticastGroup(addr);
 }
 
 void Ipv6InterfaceData::updateMatchingAddressExpiryTimes(const Ipv6Address& prefix, int length,
@@ -425,6 +430,8 @@ void Ipv6InterfaceData::removeAddress(const Ipv6Address& address)
         Ipv6AddressInfo info(ownerp, address);
         m->emit(ipv6AddressRemovedSignal, &info);
     }
+
+    leaveSolicitedNodeMulticastGroup(address);
 }
 
 bool Ipv6InterfaceData::addrLess(const AddressData& a, const AddressData& b)
@@ -448,9 +455,11 @@ void Ipv6InterfaceData::choosePreferredAddress()
     // remove expired addresses (expiryTime == 0 means infinite lifetime)
     simtime_t now = simTime();
     bool changed = false;
+    Ipv6AddressVector expired;
     for (auto it = addresses.begin(); it != addresses.end(); ) {
         if (it->expiryTime != SIMTIME_ZERO && it->expiryTime <= now) {
             EV_INFO << "Address " << it->address << " has expired, removing\n";
+            expired.push_back(it->address);
             it = addresses.erase(it);
             changed = true;
         }
@@ -460,6 +469,7 @@ void Ipv6InterfaceData::choosePreferredAddress()
 
     if (addresses.empty()) {
         preferredAddr = Ipv6Address();
+        leaveExpiredSolicitedNodeMulticastGroups(expired);
         return;
     }
 
@@ -473,27 +483,46 @@ void Ipv6InterfaceData::choosePreferredAddress()
     // right away. Falling back to a link-local source for an off-link
     // destination would be non-routable (RFC 4291 Section 2.5.6), so link-local
     // is used only when no routable address exists at all.
+    Ipv6Address routableCandidate = Ipv6Address::UNSPECIFIED_ADDRESS;
+    simtime_t routableExpiry = SIMTIME_ZERO;
     Ipv6Address linkLocalCandidate = Ipv6Address::UNSPECIFIED_ADDRESS;
     simtime_t linkLocalExpiry = SIMTIME_ZERO;
     for (auto& elem : addresses) {
         if (!elem.address.isUnicast())
             continue;
         if (!elem.address.isLinkLocal()) {
-            preferredAddr = elem.address;
-            preferredAddrExpiryTime = elem.expiryTime;
-            if (changed)
-                changed1(F_IP_ADDRESS);
-            return;
+            routableCandidate = elem.address;
+            routableExpiry = elem.expiryTime;
+            break;
         }
         if (linkLocalCandidate.isUnspecified()) {
             linkLocalCandidate = elem.address;
             linkLocalExpiry = elem.expiryTime;
         }
     }
-    preferredAddr = linkLocalCandidate;
-    preferredAddrExpiryTime = linkLocalExpiry;
+
+    if (!routableCandidate.isUnspecified()) {
+        preferredAddr = routableCandidate;
+        preferredAddrExpiryTime = routableExpiry;
+    }
+    else {
+        preferredAddr = linkLocalCandidate;
+        preferredAddrExpiryTime = linkLocalExpiry;
+    }
+
     if (changed)
         changed1(F_IP_ADDRESS);
+
+    leaveExpiredSolicitedNodeMulticastGroups(expired);
+}
+
+void Ipv6InterfaceData::leaveExpiredSolicitedNodeMulticastGroups(const Ipv6AddressVector& expired)
+{
+    // Leaving hands control to a Multicast Listener Discovery module, which builds and
+    // sends a Done message, so it must not happen until this object's own state is
+    // consistent again: the address list erased and sorted, and preferredAddr chosen.
+    for (const auto& addr : expired)
+        leaveSolicitedNodeMulticastGroup(addr);
 }
 
 void Ipv6InterfaceData::addAdvPrefix(const AdvPrefix& advPrefix)
@@ -553,6 +582,48 @@ void Ipv6InterfaceData::leaveMulticastGroup(const Ipv6Address& multicastAddress)
     changeMulticastGroupMembership(multicastAddress, MCAST_EXCLUDE_SOURCES, empty, MCAST_INCLUDE_SOURCES, empty);
 }
 
+void Ipv6InterfaceData::joinSolicitedNodeMulticastGroup(const Ipv6Address& addr)
+{
+    // RFC 4861 Section 7.2.1: "When a multicast-capable interface becomes enabled, the
+    // node MUST join the all-nodes multicast address on that interface, as well as the
+    // solicited-node multicast address corresponding to each of the IP addresses assigned
+    // to the interface." Tentative addresses are included: RFC 4862 Section 5.4.2 requires
+    // the group to be joined before the first Duplicate Address Detection probe is sent.
+    //
+    // The loopback address is excluded because it is not a link address: its solicited-node
+    // address would collide with that of every real address ending in the same 24 bits.
+    if (!isSolicitedNodeGroupOwner(addr))
+        return;
+
+    joinMulticastGroup(addr.formSolicitedNodeMulticastAddress());
+}
+
+void Ipv6InterfaceData::leaveSolicitedNodeMulticastGroup(const Ipv6Address& addr)
+{
+    // RFC 4861 Section 7.2.1: "a node MUST NOT leave the solicited-node multicast group
+    // until all assigned addresses corresponding to that multicast address have been
+    // removed." Several unicast addresses map to one solicited-node address -- with
+    // stateless autoconfiguration a link-local and a global address formed from the same
+    // interface identifier always do -- so this is the common case, not the exception.
+    // changeMulticastGroupMembership() counts the joins, so one leave per address is
+    // enough: the group entry only goes away with the last of them.
+    if (!isSolicitedNodeGroupOwner(addr))
+        return;
+
+    // Membership, not the interface flags, decides whether a leave is due. The flags are
+    // read once when the address is assigned and again here, and a leave that never had a
+    // matching join would drive the reference count in changeMulticastGroupMembership()
+    // below zero, leaving the interface a member of a group it never joined.
+    Ipv6Address solNodeAddr = addr.formSolicitedNodeMulticastAddress();
+    if (isMemberOfMulticastGroup(solNodeAddr))
+        leaveMulticastGroup(solNodeAddr);
+}
+
+bool Ipv6InterfaceData::isSolicitedNodeGroupOwner(const Ipv6Address& addr) const
+{
+    return ownerp && ownerp->isMulticast() && addr.isUnicast() && !addr.isLoopback();
+}
+
 void Ipv6InterfaceData::changeMulticastGroupMembership(Ipv6Address multicastAddress,
         McastSourceFilterMode oldFilterMode, const Ipv6AddressVector& oldSourceList,
         McastSourceFilterMode newFilterMode, const Ipv6AddressVector& newSourceList)
@@ -838,6 +909,7 @@ Ipv6Address Ipv6InterfaceData::removeAddress(Ipv6InterfaceData::AddressType type
             Ipv6AddressInfo info(ownerp, addr);
             m->emit(ipv6AddressRemovedSignal, &info);
         }
+        leaveSolicitedNodeMulticastGroup(addr);
     }
 
     return addr;

src/inet/networklayer/ipv6/Ipv6InterfaceData.h

@@ -431,6 +431,10 @@ class INET_API Ipv6InterfaceData : public InterfaceProtocolData
   protected:
     int findAddress(const Ipv6Address& addr) const;
     void choosePreferredAddress();
+    void joinSolicitedNodeMulticastGroup(const Ipv6Address& addr);
+    void leaveSolicitedNodeMulticastGroup(const Ipv6Address& addr);
+    void leaveExpiredSolicitedNodeMulticastGroups(const Ipv6AddressVector& expired);
+    bool isSolicitedNodeGroupOwner(const Ipv6Address& addr) const;
     void changed1(int fieldId) { changed(interfaceIpv6ConfigChangedSignal, fieldId); }
     HostMulticastData *getHostData() { if (!hostMcastData) hostMcastData = new HostMulticastData(); return hostMcastData; }
     const HostMulticastData *getHostData() const { return const_cast<Ipv6InterfaceData *>(this)->getHostData(); }

src/inet/networklayer/ipv6/Ipv6RoutingTable.cc

@@ -267,16 +267,17 @@ void Ipv6RoutingTable::assignRequiredNodeAddresses(NetworkInterface *ie)
     /*o  Any additional Unicast and Anycast Addresses that have been configured
        for the node's interfaces (manually or automatically).*/
 
-    // FIXME: commented out the following lines, because these addresses
-    // are implicitly checked for in isLocalAddress() (we don't want redundancy,
-    // and manually adding solicited-node mcast address for each and every address
-    // is very error-prone)
-    //
     // o  The All-Nodes Multicast Addresses defined in section 2.7.1.
+    //
+    // Joined below, together with the all-routers group.
 
     /*o  The Solicited-Node Multicast Address for each of its unicast and anycast
        addresses.*/
 
+    // Not joined here: Ipv6InterfaceData::assignAddress() joins the solicited-node group
+    // of an address as it is assigned, and leaves it as it is removed, so the membership
+    // tracks the address list on its own (RFC 4861 Section 7.2.1).
+
     // o  Multicast Addresses of all other groups to which the node belongs.
 
     /*A router is required to recognize all addresses that a host is

tests/fingerprint/examples.csv

@@ -465,15 +465,15 @@
 /examples/ospfv3/v3_square_2_areas/, -f omnetpp.ini -c General -r 0,                200s,            bbee-ed95/tplx;ac7a-261c/~tNl;025f-56b5/tyf;c1f1-6687/~tND, PASS, EthernetMac
 
 /examples/pim/dm/,             -f omnetpp.ini -c General -r 0,                300s,            5542-465a/tplx;320d-ec2e/~tNl;7540-425c/~tND;ed5b-ae9d/tyf, PASS, igmp EthernetMac Ipv4
-/examples/pim/dm_ipv6/,              -f omnetpp.ini -c General -r 0,                120s,            3c32-3dca/~tNlb, PASS, MLD EthernetMac Ipv6
+/examples/pim/dm_ipv6/,              -f omnetpp.ini -c General -r 0,                120s,            3c6e-baaf/~tNlb, PASS, MLD EthernetMac Ipv6
 /examples/pim/iptv/,                 -f omnetpp.ini -c PIM_SM -r 0,                  35s,            9fdf-a54f/tplx;c356-8a7d/~tNl;fddd-28bc/~tND;11d1-62c7/tyf, PASS, igmp ospf EthernetMac Ipv4
 /examples/pim/iptv/,                 -f omnetpp.ini -c PIM_DM -r 0,                  35s,            25e4-e1ff/tplx;280f-57ab/~tNl;6e8e-78ba/~tND;96bd-4dca/tyf, PASS, igmp ospf EthernetMac Ipv4
 /examples/pim/sm/,             -f omnetpp.ini -c Scenario1 -r 0,              100s,            3f92-7b84/tplx;1cf9-ee08/~tNl;7bc2-d697/~tND;ba86-0da1/tyf, PASS, igmp EthernetMac Ipv4
 /examples/pim/sm/,             -f omnetpp.ini -c Scenario2 -r 0,              150s,            b64f-022b/tplx;5022-893e/~tNl;9384-a10d/~tND;ce2a-7241/tyf, PASS, igmp EthernetMac Ipv4
 /examples/pim/sm/,             -f omnetpp.ini -c Scenario3 -r 0,              300s,            a4d4-39b0/tplx;2e76-520f/~tNl;eb91-fabc/~tND;4f37-e2c3/tyf, PASS, igmp EthernetMac Ipv4
 /examples/pim/sm/,             -f omnetpp.ini -c Scenario4 -r 0,              100s,            1bbc-ce82/tplx;90c6-efdf/~tNl;3c6f-feb9/~tND;015c-b31f/tyf, PASS, igmp EthernetMac Ipv4
-/examples/pim/sm_ipv6/,              -f omnetpp.ini -c General -r 0,                120s,            0a21-bad8/~tNlb, PASS, MLD EthernetMac Ipv6
-/examples/pim/ssm_ipv6/,             -f omnetpp.ini -c General -r 0,                60s,             6eba-9db0/~tNl, PASS, MLD EthernetMac Ipv6
+/examples/pim/sm_ipv6/,              -f omnetpp.ini -c General -r 0,                120s,            1dcf-20a5/~tNlb, PASS, MLD EthernetMac Ipv6
+/examples/pim/ssm_ipv6/,             -f omnetpp.ini -c General -r 0,                60s,             094d-904b/~tNl, PASS, MLD EthernetMac Ipv6
 
 /examples/seaport/,                  -f omnetpp.ini -c General -r 0,                1000s,           32cb-156a/tplx;fcf4-00cd/~tNl;e3e9-834d/tyf, PASS, igmp EthernetMac Ipv4
 

tests/fingerprint/mipv6-refactoring.csv

@@ -16,8 +16,8 @@
 # MLD example — new PASS row; ~tNl locks the MLD Report/Query/Done/MAS-Query packet exchange (traffic+lengths);
 # ~tNlb excluded: EthernetHub (WireJunction) adds a pointer-typed 'originalSender' cPar to the signal which
 # causes parsimPack() to abort — use ~tNl (no parsim serialization) instead; tyf excluded as unreliable
-/examples/ipv6/mld/,            -f omnetpp.ini -c MldDemo -r 0,              30s,             f1b1-b523/~tNl, PASS, EthernetMac MLD
-/examples/ipv6/mld/,            -f omnetpp.ini -c MldV2Ssm -r 0,            30s,             a22a-81c9/~tNl, PASS, EthernetMac MLD
+/examples/ipv6/mld/,            -f omnetpp.ini -c MldDemo -r 0,              30s,             e72b-4cc1/~tNl, PASS, EthernetMac MLD
+/examples/ipv6/mld/,            -f omnetpp.ini -c MldV2Ssm -r 0,            30s,             f947-4b1c/~tNl, PASS, EthernetMac MLD
 /examples/ipv6/nclients/,            -f omnetpp.ini -c ETH -r 0,                    1000s,           50c9-9bb3/~tNlb, PASS, EthernetMac
 /examples/ipv6/nclients/,            -f omnetpp.ini -c PPP -r 0,                    1000s,           0e0c-b800/~tNlb, PASS,
 /examples/ipv6/nclients/,            -f omnetpp.ini -c PPP_SCTP -r 0,               100s,            06b9-ff17/~tNlb, PASS,

tests/module/IPv6_solicited_node_group_join.test

@@ -0,0 +1,105 @@
+%description:
+Tests that a node joins the solicited-node multicast group of every address
+assigned to an interface, and announces the membership with a Multicast
+Listener Report before it probes the address.
+
+RFC 4861 Section 7.2.1 requires a node to join the solicited-node multicast
+address corresponding to each of the IP addresses assigned to an interface,
+and to join and leave as addresses are added and removed. RFC 4862 Section
+5.4.2 requires the join to happen before the first Duplicate Address
+Detection probe of a tentative address, because with an MLD-snooping switch
+"no multicast reception will be available until the MLD report is sent".
+
+A router and a host obtain their addresses by Stateless Address
+Autoconfiguration, with Multicast Listener Discovery enabled so that each
+join becomes a packet. The host's interface identifier is fixed by its MAC
+address, so its link-local address is fe80::8aa:ff:fe00:2 and the
+solicited-node group of that address is ff02::1:ff00:2.
+
+%#--------------------------------------------------------------------------------------------------------------
+%file: test.ned
+import inet.networklayer.configurator.ipv6.Ipv6FlatNetworkConfigurator;
+import inet.node.ipv6.Router6;
+import inet.node.ipv6.StandardHost6;
+import ned.DatarateChannel;
+
+network SolicitedNodeJoinNetwork
+{
+    types:
+        channel ethline extends DatarateChannel
+        {
+            delay = 0.1us;
+            datarate = 10Mbps;
+        }
+    submodules:
+        configurator: Ipv6FlatNetworkConfigurator;
+        router: Router6;
+        host: StandardHost6;
+    connections:
+        host.ethg++ <--> ethline <--> router.ethg++;
+}
+%#--------------------------------------------------------------------------------------------------------------
+%inifile: omnetpp.ini
+[General]
+record-vector-results = false
+ned-path = ../../../../src
+network = SolicitedNodeJoinNetwork
+sim-time-limit = 5s
+cmdenv-express-mode = false
+cmdenv-log-prefix = "%C: "
+
+# Multicast Listener Discovery makes every join visible as a packet.
+**.ipv6.hasMld = true
+
+# One probe per address is enough, and keeps the log short.
+**.neighbourDiscovery.dupAddrDetectTransmits = 1
+
+# Ethernet NIC configuration
+**.eth[*].queue.typename = "EthernetQosQueue"
+**.eth[*].queue.dataQueue.typename = "DropTailQueue"
+**.eth[*].queue.dataQueue.packetCapacity = 10
+
+%#--------------------------------------------------------------------------------------------------------------
+%subst: /omnetpp:://
+%#--------------------------------------------------------------------------------------------------------------
+%#
+%# The host announces the solicited-node group of its link-local address.
+%#
+%contains: stdout
+SolicitedNodeJoinNetwork.host.ipv6.mld: Mldv1: sending Multicast Listener Report for group=ff02::1:ff00:2 on iface=eth0
+
+%#
+%# The report precedes the host's own first Duplicate Address Detection probe
+%# (RFC 4862 Section 5.4.2). Both greps are anchored on the host, so the
+%# router's earlier probe cannot satisfy the ordering; grep -n keeps the file
+%# order, so an ordered match over the two line numbers is enough.
+%#
+%postrun-command: grep -n "host\.ipv6\.mld: .*Report for group=ff02::1:ff00:2\|host\.ipv6\.neighbourDiscovery: .*INITIATING DUPLICATE ADDRESS" test.out | head -2 > order.out || true
+%contains-regex: order.out
+[0-9]+:.*host\.ipv6\.mld: .*Report for group=ff02::1:ff00:2.*\n[0-9]+:.*host\.ipv6\.neighbourDiscovery: .*INITIATING DUPLICATE ADDRESS
+
+%#
+%# The host holds two addresses -- the link-local one and the global one it
+%# forms from the router's prefix -- and probes both, so it runs Duplicate
+%# Address Detection twice.
+%#
+%postrun-command: grep -c "host\.ipv6\.neighbourDiscovery: .*INITIATING DUPLICATE ADDRESS" test.out > dadcount.out || true
+%contains: dadcount.out
+2
+
+%#
+%# Both addresses carry the same interface identifier, so both map to the same
+%# solicited-node group and the second join finds the group already joined.
+%# RFC 4861 Section 7.2.1 requires exactly that: "multiple unicast addresses
+%# may map into the same solicited-node multicast address". The second join
+%# changes no state and emits no further report, so two addresses produce one
+%# report, not two.
+%#
+%postrun-command: grep -c "host\.ipv6\.mld: .*sending Multicast Listener Report for group=ff02::1:ff00:2" test.out > joincount.out || true
+%contains: joincount.out
+1
+%#--------------------------------------------------------------------------------------------------------------
+%postrun-command: grep "undisposed object:" test.out > test_undisposed.out || true
+%not-contains: test_undisposed.out
+undisposed object: (
+%#--------------------------------------------------------------------------------------------------------------

tests/module/MLDv2_host_query.test

@@ -61,9 +61,12 @@ network = inet.test.moduletest.lib.TestMLDNetwork
 %# First check that the join/set-filter were applied to the interface state
 %#
 %postrun-command: grep "TestMld: .*groups =" test.out > groups.out || true
+%# ff02::1:ff00:1 is the solicited-node multicast group of the interface's own address,
+%# joined when that address is assigned (RFC 4861 Section 7.2.1), so it is a member of
+%# every dump and of every Current-State Report below.
 %contains: groups.out
-TestMld: eth0: groups = ff3e::1 I 2001::1.
-TestMld: eth0: groups = ff3e::1 E 2001::2.
+TestMld: eth0: groups = ff02::1:ff00:1 E, ff3e::1 I 2001::1.
+TestMld: eth0: groups = ff02::1:ff00:1 E, ff3e::1 E 2001::2.
 
 %#
 %# Now check that the Mldv2 module responded to each General Query with a Current-State
@@ -75,10 +78,10 @@ TestMld: eth0: groups = ff3e::1 E 2001::2.
 %postrun-command: grep "TestMld: .*Received" test.out > received.out || true
 %contains-regex: received.out
 TestMld: Received: inet::Mldv2Report<ff3e::1=ALLOW \(2001::1\)>.
-(?:.*\n)*?TestMld: Received: inet::Mldv2Report<ff3e::1=IS_IN \(2001::1\)>.
+(?:.*\n)*?TestMld: Received: inet::Mldv2Report<ff02::1:ff00:1=IS_EX, ff3e::1=IS_IN \(2001::1\)>.
 (?:.*\n)*?TestMld: Received: inet::Mldv2Report<ff3e::1=ALLOW \(2001::1\)>.
 (?:.*\n)*?TestMld: Received: inet::Mldv2Report<ff3e::1=TO_EX \(2001::2\)>.
-(?:.*\n)*?TestMld: Received: inet::Mldv2Report<ff3e::1=IS_EX \(2001::2\)>.
+(?:.*\n)*?TestMld: Received: inet::Mldv2Report<ff02::1:ff00:1=IS_EX, ff3e::1=IS_EX \(2001::2\)>.
 (?:.*\n)*?TestMld: Received: inet::Mldv2Report<ff3e::1=TO_EX \(2001::2\)>.
 
 %#