[nexus] update mDNS traffic to flow through infrastructure link (#12720)

Update mDNS traffic simulation in the Nexus platform to flow through
the simulated infrastructure link. This ensures mDNS packets are
automatically written to the PCAP file generated by the simulated
infrastructure link.

Changes:
- Wrap mDNS messages in UDP/IPv6 headers and enqueue them on the
  simulated infrastructure interface (InfraIf).
- Implement a new SendUdp overload in InfraIf that accepts a Message
  payload.
- Update InfraIf::Receive to intercept mDNS UDP packets (port 5353)
  and deliver them to the Mdns module.
- Remove the dedicated ProcessMdns loop and manual PendingTx list from
  Core and Mdns, consolidating traffic processing through InfraIf.
- Initialize Mdns with a reference to the Node to allow access to
  InfraIf.
- Add GetMulticastAddress static helper to Mdns for 'ff02::fb'.

tests/nexus/platform/nexus_core.cpp

@@ -282,6 +282,7 @@ Node &Core::CreateNode(void)
     node->GetInstance().SetId(mCurNodeId++);
 
     node->mInfraIf.Init(*node);
+    node->mMdns.Init(*node);
 
     mNodes.Push(*node);
 
@@ -362,7 +363,6 @@ void Core::Process(Node &aNode)
     otTaskletsProcess(&aNode.GetInstance());
 
     ProcessRadio(aNode);
-    ProcessMdns(aNode);
     ProcessInfraIf(aNode);
 #if OPENTHREAD_CONFIG_RADIO_LINK_TREL_ENABLE
     ProcessTrel(aNode);
@@ -528,23 +528,6 @@ exit:
     return;
 }
 
-void Core::ProcessMdns(Node &aNode)
-{
-    Mdns::AddressInfo senderAddress;
-
-    aNode.mMdns.GetAddress(senderAddress);
-
-    for (Mdns::PendingTx &pendingTx : aNode.mMdns.mPendingTxList)
-    {
-        for (Node &rxNode : mNodes)
-        {
-            rxNode.mMdns.Receive(rxNode.GetInstance(), pendingTx, senderAddress);
-        }
-    }
-
-    aNode.mMdns.mPendingTxList.Free();
-}
-
 void Core::ProcessInfraIf(Node &aNode)
 {
     // Deliver pending packets on the infrastructure interface.
@@ -616,7 +599,7 @@ void Core::ProcessInfraIf(Node &aNode)
                 continue;
             }
 
-            rxNode.mInfraIf.Receive(aNode, header, *message);
+            rxNode.mInfraIf.Receive(aNode, *message);
         }
 
         message->Free();

tests/nexus/platform/nexus_core.hpp

@@ -110,7 +110,6 @@ private:
 
     void Process(Node &aNode);
     void ProcessRadio(Node &aNode);
-    void ProcessMdns(Node &aNode);
     void ProcessInfraIf(Node &aNode);
 #if OPENTHREAD_CONFIG_RADIO_LINK_TREL_ENABLE
     void ProcessTrel(Node &aNode);

tests/nexus/platform/nexus_infra_if.cpp

@@ -74,6 +74,7 @@ void InfraIf::AddAddress(const Ip6::Address &aAddress)
     VerifyOrExit(!HasAddress(aAddress));
 
     SuccessOrQuit(mAddresses.PushBack(aAddress));
+    mNode->mMdns.HandleHostAddressEvent(aAddress, /* aAdded */ true);
 
 exit:
     return;
@@ -87,11 +88,18 @@ void InfraIf::RemoveAddress(const Ip6::Address &aAddress)
         {
             mAddresses[index] = *mAddresses.Back();
             mAddresses.PopBack();
+            mNode->mMdns.HandleHostAddressEvent(aAddress, /* aAdded */ false);
             break;
         }
     }
 }
 
+void InfraIf::RemoveAllAddresses(void)
+{
+    mAddresses.Clear();
+    mNode->mMdns.HandleHostAddressRemoveAll();
+}
+
 const Ip6::Address *InfraIf::FindAddress(const char *aPrefix) const
 {
     Ip6::Prefix         prefix;
@@ -289,16 +297,26 @@ void InfraIf::SendUdp(const Ip6::Address &aSrcAddress,
                       uint16_t            aDestPort,
                       uint16_t            aPayloadSize)
 {
-    Message         *message;
+    Message *message = GetNode().Get<Ip6::Ip6>().NewMessage();
+
+    VerifyOrQuit(message != nullptr);
+
+    SuccessOrQuit(message->IncreaseLength(aPayloadSize));
+    SendUdp(aSrcAddress, aDestAddress, aSourcePort, aDestPort, *message);
+}
+
+void InfraIf::SendUdp(const Ip6::Address &aSrcAddress,
+                      const Ip6::Address &aDestAddress,
+                      uint16_t            aSourcePort,
+                      uint16_t            aDestPort,
+                      Message            &aPayload)
+{
     Ip6::Header      ip6Header;
     Ip6::Udp::Header udpHeader;
 
-    message = GetNode().Get<Ip6::Ip6>().NewMessage();
-    VerifyOrQuit(message != nullptr);
-
     ip6Header.Clear();
     ip6Header.InitVersionTrafficClassFlow();
-    ip6Header.SetPayloadLength(sizeof(Ip6::Udp::Header) + aPayloadSize);
+    ip6Header.SetPayloadLength(sizeof(Ip6::Udp::Header) + aPayload.GetLength());
     ip6Header.SetNextHeader(Ip6::kProtoUdp);
     ip6Header.SetHopLimit(64);
     ip6Header.SetSource(aSrcAddress);
@@ -306,94 +324,110 @@ void InfraIf::SendUdp(const Ip6::Address &aSrcAddress,
 
     udpHeader.SetSourcePort(aSourcePort);
     udpHeader.SetDestinationPort(aDestPort);
-    udpHeader.SetLength(sizeof(Ip6::Udp::Header) + aPayloadSize);
+    udpHeader.SetLength(sizeof(Ip6::Udp::Header) + aPayload.GetLength());
     udpHeader.SetChecksum(0);
 
-    SuccessOrQuit(message->Append(udpHeader));
+    SuccessOrQuit(aPayload.Prepend(udpHeader));
-    SuccessOrQuit(message->IncreaseLength(aPayloadSize));
+    aPayload.SetOffset(0);
+    Checksum::UpdateMessageChecksum(aPayload, aSrcAddress, aDestAddress, Ip6::kProtoUdp);
+    SuccessOrQuit(aPayload.Prepend(ip6Header));
+    aPayload.SetOffset(0);
 
-    Checksum::UpdateMessageChecksum(*message, aSrcAddress, aDestAddress, Ip6::kProtoUdp);
+    if (aDestAddress.IsMulticast())
+    {
+        Message *loopbackMessage = aPayload.Clone();
 
-    SuccessOrQuit(message->Prepend(ip6Header));
+        VerifyOrQuit(loopbackMessage != nullptr);
+        Receive(GetNode(), *loopbackMessage);
+        loopbackMessage->Free();
+    }
 
-    mPendingTxQueue.Enqueue(*message);
+    mPendingTxQueue.Enqueue(aPayload);
 }
 
-void InfraIf::Receive(Node &aSrcNode, const Ip6::Header &aHeader, Message &aMessage)
+void InfraIf::Receive(Node &aSrcNode, Message &aMessage)
 {
-    Node &node          = GetNode();
+    Node        &node = GetNode();
-    bool  isIcmp6Nd     = false;
+    Ip6::Headers headers;
-    bool  isEchoRequest = false;
-    bool  isEchoReply   = false;
-
-    VerifyOrExit(!node.mInfraIf.HasAddress(aHeader.GetSource()));
-    VerifyOrExit(!node.Get<NetworkData::Leader>().IsOnMesh(aHeader.GetSource()));
-
-#if OPENTHREAD_FTD && OPENTHREAD_CONFIG_BACKBONE_ROUTER_MULTICAST_ROUTING_ENABLE
-    if (aHeader.GetDestination().IsMulticastLargerThanRealmLocal())
-    {
-        VerifyOrExit(node.Get<BackboneRouter::Local>().IsPrimary());
-        VerifyOrExit(node.Get<BackboneRouter::MulticastListenersTable>().Has(aHeader.GetDestination()));
-    }
-#endif
 
     Core::Get().SetActiveNode(&node);
 
-    if (aHeader.GetNextHeader() == Ip6::kProtoIcmp6 &&
+    aMessage.SetOffset(0);
-        aMessage.GetLength() >= sizeof(Ip6::Header) + sizeof(Ip6::Icmp::Header) &&
+    SuccessOrExit(headers.ParseFrom(aMessage));
-        (aHeader.GetDestination() == Ip6::Address::GetLinkLocalAllNodesMulticast() ||
+
-         aHeader.GetDestination() == Ip6::Address::GetLinkLocalAllRoutersMulticast() ||
+    if (headers.IsIcmp6() && (headers.GetDestinationAddress() == Ip6::Address::GetLinkLocalAllNodesMulticast() ||
-         node.mInfraIf.HasAddress(aHeader.GetDestination())))
+                              headers.GetDestinationAddress() == Ip6::Address::GetLinkLocalAllRoutersMulticast() ||
+                              node.mInfraIf.HasAddress(headers.GetDestinationAddress())))
     {
-        Ip6::Icmp::Header icmpHeader;
+        switch (headers.GetIcmpHeader().GetType())
-
-        SuccessOrQuit(aMessage.Read(sizeof(Ip6::Header), icmpHeader));
-
-        switch (icmpHeader.GetType())
         {
         case Ip6::Icmp::Header::kTypeRouterAdvert:
         case Ip6::Icmp::Header::kTypeRouterSolicit:
         case Ip6::Icmp::Header::kTypeNeighborAdvert:
         case Ip6::Icmp::Header::kTypeNeighborSolicit:
-            isIcmp6Nd = true;
+        {
-            break;
+            Heap::Data payload;
+            uint16_t   offset = sizeof(Ip6::Header);
+
+            SuccessOrQuit(payload.SetFrom(aMessage, offset, aMessage.GetLength() - offset));
+
+            otPlatInfraIfRecvIcmp6Nd(&node.GetInstance(), mIfIndex,
+                                     reinterpret_cast<const otIp6Address *>(&headers.GetSourceAddress()),
+                                     payload.GetBytes(), payload.GetLength());
+            node.mInfraIf.ProcessIcmp6Nd(headers.GetSourceAddress(), payload.GetBytes(), payload.GetLength());
+            ExitNow();
+        }
+
         case Ip6::Icmp::Header::kTypeEchoRequest:
-            isEchoRequest = true;
+            HandleEchoRequest(headers.GetIp6Header(), aMessage);
-            break;
+            ExitNow();
+
         case Ip6::Icmp::Header::kTypeEchoReply:
-            isEchoReply = true;
+            HandleEchoReply(headers.GetIp6Header(), aMessage);
-            break;
+            ExitNow();
+
         default:
             break;
         }
     }
 
-    if (isIcmp6Nd)
+    if (headers.IsUdp() && headers.GetDestinationPort() == Mdns::kUdpPort)
     {
-        Heap::Data payload;
+        if (headers.GetDestinationAddress().IsMulticast() || node.mInfraIf.HasAddress(headers.GetDestinationAddress()))
-        uint16_t   offset = sizeof(Ip6::Header);
+        {
+            Mdns::AddressInfo senderAddress;
+            Message          *payload = aMessage.Clone();
 
-        SuccessOrQuit(payload.SetFrom(aMessage, offset, aMessage.GetLength() - offset));
+            VerifyOrQuit(payload != nullptr);
+            payload->RemoveHeader(sizeof(Ip6::Header) + sizeof(Ip6::Udp::Header));
 
-        otPlatInfraIfRecvIcmp6Nd(&node.GetInstance(), mIfIndex,
+            senderAddress.mAddress      = headers.GetSourceAddress();
-                                 reinterpret_cast<const otIp6Address *>(&aHeader.GetSource()), payload.GetBytes(),
+            senderAddress.mPort         = headers.GetSourcePort();
-                                 payload.GetLength());
+            senderAddress.mInfraIfIndex = Mdns::kInfraIfIndex;
-        node.mInfraIf.ProcessIcmp6Nd(aHeader.GetSource(), payload.GetBytes(), payload.GetLength());
+
+            node.mMdns.Receive(node.GetInstance(), *payload, !headers.GetDestinationAddress().IsMulticast(),
+                               senderAddress);
+            payload->Free();
+        }
+        ExitNow();
     }
-    else if (isEchoRequest)
+
-    {
-        HandleEchoRequest(aHeader, aMessage);
-    }
-    else if (isEchoReply)
-    {
-        HandleEchoReply(aHeader, aMessage);
-    }
-    else
     {
         // We also deliver generic IPv6 packets to the stack if they are NOT ICMPv6 ND packets.
         // (ND packets were already delivered via otPlatInfraIfRecvIcmp6Nd above).
         OwnedPtr<Message> messagePtr;
-        Ip6::Header       updatedHeader = aHeader;
+        Ip6::Header       updatedHeader = headers.GetIp6Header();
+
+        VerifyOrExit(!node.mInfraIf.HasAddress(headers.GetSourceAddress()));
+        VerifyOrExit(!node.Get<NetworkData::Leader>().IsOnMesh(headers.GetSourceAddress()));
+
+#if OPENTHREAD_FTD && OPENTHREAD_CONFIG_BACKBONE_ROUTER_MULTICAST_ROUTING_ENABLE
+        if (headers.GetDestinationAddress().IsMulticastLargerThanRealmLocal())
+        {
+            VerifyOrExit(node.Get<BackboneRouter::Local>().IsPrimary());
+            VerifyOrExit(node.Get<BackboneRouter::MulticastListenersTable>().Has(headers.GetDestinationAddress()));
+        }
+#endif
 
         VerifyOrExit(updatedHeader.GetHopLimit() > 1);
         updatedHeader.SetHopLimit(updatedHeader.GetHopLimit() - 1);
@@ -408,10 +442,8 @@ void InfraIf::Receive(Node &aSrcNode, const Ip6::Header &aHeader, Message &aMess
         SuccessOrQuit(node.Get<Ip6::Ip6>().SendRaw(messagePtr.PassOwnership()));
     }
 
-    Core::Get().SetActiveNode(&aSrcNode);
-
 exit:
-    return;
+    Core::Get().SetActiveNode(&aSrcNode);
 }
 
 void InfraIf::HandleEchoRequest(const Ip6::Header &aHeader, Message &aMessage)

tests/nexus/platform/nexus_infra_if.hpp

@@ -40,7 +40,7 @@ class Node;
 class InfraIf
 {
 public:
-    typedef otPlatInfraIfLinkLayerAddress LinkLayerAddress; ///< A link-layer address
+    typedef otPlatInfraIfLinkLayerAddress LinkLayerAddress;
 
     InfraIf(void);
 
@@ -51,11 +51,13 @@ public:
     bool HasAddress(const Ip6::Address &aAddress) const;
     void AddAddress(const Ip6::Address &aAddress);
     void RemoveAddress(const Ip6::Address &aAddress);
+    void RemoveAllAddresses(void);
 
     const Ip6::Address *FindAddress(const char *aPrefix) const;
     const Ip6::Address &FindMatchingAddress(const char *aPrefix) const;
 
-    const Ip6::Address &GetLinkLocalAddress(void) const { return mAddresses[0]; }
+    const Ip6::Address              &GetLinkLocalAddress(void) const { return mAddresses[0]; }
+    const Heap::Array<Ip6::Address> &GetAddresses(void) const { return mAddresses; }
 
     void SendIcmp6Nd(const Ip6::Address &aDestAddress, const uint8_t *aBuffer, uint16_t aBufferLength);
     void SendIp6(const Ip6::Address &aSrcAddress,
@@ -72,7 +74,13 @@ public:
                  uint16_t            aSourcePort,
                  uint16_t            aDestPort,
                  uint16_t            aPayloadSize);
-    void Receive(Node &aSrcNode, const Ip6::Header &aHeader, Message &aMessage);
+    void SendUdp(const Ip6::Address &aSrcAddress,
+                 const Ip6::Address &aDestAddress,
+                 uint16_t            aSourcePort,
+                 uint16_t            aDestPort,
+                 Message            &aPayload);
+
+    void Receive(Node &aSrcNode, Message &aMessage);
     void GetLinkLayerAddress(LinkLayerAddress &aLinkLayerAddress) const;
 
     typedef void (*EchoReplyHandler)(void *aContext, const Ip6::Address &aSource, uint16_t aId, uint16_t aSequence);

tests/nexus/platform/nexus_mdns.cpp

@@ -60,22 +60,14 @@ void otPlatMdnsSendUnicast(otInstance *aInstance, otMessage *aMessage, const otP
 // Mdns
 
 Mdns::Mdns(void)
-    : mEnabled(false)
+    : mNode(nullptr)
+    , mEnabled(false)
 {
-    Ip6::Address             address;
-    Ip6::InterfaceIdentifier iid;
-
-    iid.GenerateRandom();
-    address.SetToLinkLocalAddress(iid);
-
-    SuccessOrQuit(mIfAddresses.PushBack(address));
 }
 
-void Mdns::Reset(void)
+void Mdns::Init(Node &aNode) { mNode = &aNode; }
-{
+
-    mEnabled = false;
+void Mdns::Reset(void) { mEnabled = false; }
-    mPendingTxList.Free();
-}
 
 Error Mdns::SetListeningEnabled(Instance &aInstance, bool aEnable, uint32_t aInfraIfIndex)
 {
@@ -96,7 +88,7 @@ exit:
 
 void Mdns::SendMulticast(Message &aMessage, uint32_t aInfraIfIndex)
 {
-    PendingTx *pendingTx;
+    Ip6::Address multicastAddress;
 
     if (aInfraIfIndex != kInfraIfIndex)
     {
@@ -104,13 +96,8 @@ void Mdns::SendMulticast(Message &aMessage, uint32_t aInfraIfIndex)
         ExitNow();
     }
 
-    pendingTx = PendingTx::Allocate();
+    GetMulticastAddress(multicastAddress);
-    VerifyOrQuit(pendingTx != nullptr);
+    mNode->mInfraIf.SendUdp(mNode->mInfraIf.GetLinkLocalAddress(), multicastAddress, kUdpPort, kUdpPort, aMessage);
-
-    pendingTx->mMessage.Reset(&aMessage);
-    pendingTx->mIsUnicast = false;
-
-    mPendingTxList.PushAfterTail(*pendingTx);
 
 exit:
     return;
@@ -118,22 +105,14 @@ exit:
 
 void Mdns::SendUnicast(Message &aMessage, const AddressInfo &aAddress)
 {
-    PendingTx *pendingTx;
-
     if (aAddress.mInfraIfIndex != kInfraIfIndex)
     {
         aMessage.Free();
         ExitNow();
     }
 
-    pendingTx = PendingTx::Allocate();
+    mNode->mInfraIf.SendUdp(mNode->mInfraIf.GetLinkLocalAddress(), AsCoreType(&aAddress.mAddress), kUdpPort,
-    VerifyOrQuit(pendingTx != nullptr);
+                            aAddress.mPort, aMessage);
-
-    pendingTx->mMessage.Reset(&aMessage);
-    pendingTx->mIsUnicast = true;
-    pendingTx->mAddress   = aAddress;
-
-    mPendingTxList.PushAfterTail(*pendingTx);
 
 exit:
     return;
@@ -143,29 +122,28 @@ void Mdns::SignalIfAddresses(Instance &aInstance)
 {
     otPlatMdnsHandleHostAddressRemoveAll(&aInstance, kInfraIfIndex);
 
-    for (const Ip6::Address &address : mIfAddresses)
+    for (const Ip6::Address &address : mNode->mInfraIf.GetAddresses())
     {
         otPlatMdnsHandleHostAddressEvent(&aInstance, &address, /* aAdded */ true, kInfraIfIndex);
     }
 }
 
-void Mdns::Receive(Instance &aInstance, const PendingTx &aPendingTx, const AddressInfo &aSenderAddress)
+void Mdns::Receive(Instance &aInstance, Message &aMessage, bool aIsUnicast, const AddressInfo &aSenderAddress)
 {
     Message *message;
 
     VerifyOrExit(mEnabled);
 
-    if (aPendingTx.mIsUnicast)
+    if (aIsUnicast)
     {
-        VerifyOrExit(aPendingTx.mAddress.mInfraIfIndex == kInfraIfIndex);
+        VerifyOrExit(aSenderAddress.mInfraIfIndex == kInfraIfIndex);
-        VerifyOrExit(aPendingTx.mAddress.mPort == kUdpPort);
+        VerifyOrExit(aSenderAddress.mPort == kUdpPort);
-        VerifyOrExit(mIfAddresses.Contains(AsCoreType(&aPendingTx.mAddress.mAddress)));
     }
 
-    message = aPendingTx.mMessage->Clone();
+    message = aMessage.Clone();
     VerifyOrQuit(message != nullptr);
 
-    otPlatMdnsHandleReceive(&aInstance, message, aPendingTx.mIsUnicast, &aSenderAddress);
+    otPlatMdnsHandleReceive(&aInstance, message, aIsUnicast, &aSenderAddress);
 
 exit:
     return;
@@ -174,10 +152,28 @@ exit:
 void Mdns::GetAddress(AddressInfo &aAddress) const
 {
     ClearAllBytes(aAddress);
-    aAddress.mAddress      = mIfAddresses[0];
+    aAddress.mAddress      = mNode->mInfraIf.GetLinkLocalAddress();
     aAddress.mPort         = kUdpPort;
     aAddress.mInfraIfIndex = kInfraIfIndex;
 }
 
+void Mdns::HandleHostAddressEvent(const Ip6::Address &aAddress, bool aAdded)
+{
+    if (mEnabled)
+    {
+        otPlatMdnsHandleHostAddressEvent(&mNode->GetInstance(), &aAddress, aAdded, kInfraIfIndex);
+    }
+}
+
+void Mdns::HandleHostAddressRemoveAll(void)
+{
+    if (mEnabled)
+    {
+        otPlatMdnsHandleHostAddressRemoveAll(&mNode->GetInstance(), kInfraIfIndex);
+    }
+}
+
+void Mdns::GetMulticastAddress(Ip6::Address &aAddress) { SuccessOrQuit(aAddress.FromString("ff02::fb")); }
+
 } // namespace Nexus
 } // namespace ot

tests/nexus/platform/nexus_mdns.hpp

@@ -34,6 +34,8 @@
 namespace ot {
 namespace Nexus {
 
+class Node;
+
 class Mdns
 {
 public:
@@ -42,27 +44,23 @@ public:
 
     using AddressInfo = otPlatMdnsAddressInfo;
 
-    struct PendingTx : public Heap::Allocatable<PendingTx>, public LinkedListEntry<PendingTx>
-    {
-        PendingTx        *mNext;
-        OwnedPtr<Message> mMessage;
-        bool              mIsUnicast;
-        AddressInfo       mAddress;
-    };
-
     Mdns(void);
+    void  Init(Node &aNode);
     void  Reset(void);
     Error SetListeningEnabled(Instance &aInstance, bool aEnable, uint32_t aInfraIfIndex);
     void  SendMulticast(Message &aMessage, uint32_t aInfraIfIndex);
     void  SendUnicast(Message &aMessage, const AddressInfo &aAddress);
 
     void SignalIfAddresses(Instance &aInstance);
-    void Receive(Instance &aInstance, const PendingTx &aPendingTx, const AddressInfo &aSenderAddress);
+    void Receive(Instance &aInstance, Message &aMessage, bool aIsUnicast, const AddressInfo &aSenderAddress);
     void GetAddress(AddressInfo &aAddress) const;
+    void HandleHostAddressEvent(const Ip6::Address &aAddress, bool aAdded);
+    void HandleHostAddressRemoveAll(void);
 
-    bool                      mEnabled;
+    static void GetMulticastAddress(Ip6::Address &aAddress);
-    Heap::Array<Ip6::Address> mIfAddresses;
+
-    OwningList<PendingTx>     mPendingTxList;
+    Node *mNode;
+    bool  mEnabled;
 };
 
 } // namespace Nexus

tests/nexus/platform/nexus_node.cpp

@@ -188,7 +188,7 @@ exit:
 #if OPENTHREAD_CONFIG_RADIO_LINK_TREL_ENABLE
 void Node::GetTrelSockAddr(Ip6::SockAddr &aSockAddr) const
 {
-    aSockAddr.SetAddress(mMdns.mIfAddresses[0]);
+    aSockAddr.SetAddress(mInfraIf.GetLinkLocalAddress());
     aSockAddr.SetPort(mTrel.mUdpPort);
 }
 #endif

tests/nexus/test_trel.cpp

@@ -290,9 +290,9 @@ void TestTrelDelayedMdnsStartAndPeerRemovalDelay(void)
     VerifyOrQuit(StringStartsWith(peer->GetHostName(), "ot"));
     VerifyOrQuit(StringEndsWith(peer->GetHostName(), node2.Get<Mac::Mac>().GetExtAddress().ToString().AsCString()));
     VerifyOrQuit(peer->GetSockAddr().GetPort() == node2.mTrel.mUdpPort);
-    VerifyOrQuit(peer->GetSockAddr().GetAddress() == node2.mMdns.mIfAddresses[0]);
+    VerifyOrQuit(peer->GetSockAddr().GetAddress() == node2.mInfraIf.GetLinkLocalAddress());
     VerifyOrQuit(peer->GetHostAddresses().GetLength() == 1);
-    VerifyOrQuit(peer->GetHostAddresses()[0] == node2.mMdns.mIfAddresses[0]);
+    VerifyOrQuit(peer->GetHostAddresses()[0] == node2.mInfraIf.GetLinkLocalAddress());
     VerifyOrQuit(peer->GetNext() == nullptr);
 
     // Check peer on `node2` to match `node1` info.
@@ -308,9 +308,9 @@ void TestTrelDelayedMdnsStartAndPeerRemovalDelay(void)
     VerifyOrQuit(StringStartsWith(peer->GetHostName(), "ot"));
     VerifyOrQuit(StringEndsWith(peer->GetHostName(), node1.Get<Mac::Mac>().GetExtAddress().ToString().AsCString()));
     VerifyOrQuit(peer->GetSockAddr().GetPort() == node1.mTrel.mUdpPort);
-    VerifyOrQuit(peer->GetSockAddr().GetAddress() == node1.mMdns.mIfAddresses[0]);
+    VerifyOrQuit(peer->GetSockAddr().GetAddress() == node1.mInfraIf.GetLinkLocalAddress());
     VerifyOrQuit(peer->GetHostAddresses().GetLength() == 1);
-    VerifyOrQuit(peer->GetHostAddresses()[0] == node1.mMdns.mIfAddresses[0]);
+    VerifyOrQuit(peer->GetHostAddresses()[0] == node1.mInfraIf.GetLinkLocalAddress());
 
     // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
     Log("Disable TREL Interface (and `PeerDiscoverer`) on `node2`");
@@ -360,9 +360,9 @@ void TestTrelDelayedMdnsStartAndPeerRemovalDelay(void)
     VerifyOrQuit(StringStartsWith(peer->GetHostName(), "ot"));
     VerifyOrQuit(StringEndsWith(peer->GetHostName(), node2.Get<Mac::Mac>().GetExtAddress().ToString().AsCString()));
     VerifyOrQuit(peer->GetSockAddr().GetPort() == node2.mTrel.mUdpPort);
-    VerifyOrQuit(peer->GetSockAddr().GetAddress() == node2.mMdns.mIfAddresses[0]);
+    VerifyOrQuit(peer->GetSockAddr().GetAddress() == node2.mInfraIf.GetLinkLocalAddress());
     VerifyOrQuit(peer->GetHostAddresses().GetLength() == 1);
-    VerifyOrQuit(peer->GetHostAddresses()[0] == node2.mMdns.mIfAddresses[0]);
+    VerifyOrQuit(peer->GetHostAddresses()[0] == node2.mInfraIf.GetLinkLocalAddress());
     VerifyOrQuit(peer->GetNext() == nullptr);
 
     // Check peer on `node2` to match `node1` info.
@@ -378,9 +378,9 @@ void TestTrelDelayedMdnsStartAndPeerRemovalDelay(void)
     VerifyOrQuit(StringStartsWith(peer->GetHostName(), "ot"));
     VerifyOrQuit(StringEndsWith(peer->GetHostName(), node1.Get<Mac::Mac>().GetExtAddress().ToString().AsCString()));
     VerifyOrQuit(peer->GetSockAddr().GetPort() == node1.mTrel.mUdpPort);
-    VerifyOrQuit(peer->GetSockAddr().GetAddress() == node1.mMdns.mIfAddresses[0]);
+    VerifyOrQuit(peer->GetSockAddr().GetAddress() == node1.mInfraIf.GetLinkLocalAddress());
     VerifyOrQuit(peer->GetHostAddresses().GetLength() == 1);
-    VerifyOrQuit(peer->GetHostAddresses()[0] == node1.mMdns.mIfAddresses[0]);
+    VerifyOrQuit(peer->GetHostAddresses()[0] == node1.mInfraIf.GetLinkLocalAddress());
 
     peer = node1.Get<ot::Trel::PeerTable>().GetHead();
     VerifyOrQuit(peer != nullptr);
@@ -406,7 +406,7 @@ void TestTrelDelayedMdnsStartAndPeerRemovalDelay(void)
     VerifyOrQuit(peer->GetDnssdState() == kDnssdRemoved);
     VerifyOrQuit(peer->GetExtPanId() == node2.Get<MeshCoP::NetworkIdentity>().GetExtPanId());
     VerifyOrQuit(peer->GetExtAddress() == node2.Get<Mac::Mac>().GetExtAddress());
-    VerifyOrQuit(peer->GetSockAddr().GetAddress() == node2.mMdns.mIfAddresses[0]);
+    VerifyOrQuit(peer->GetSockAddr().GetAddress() == node2.mInfraIf.GetLinkLocalAddress());
 
     Log("Validate the `DetermineSecondsSinceLastInteraction()` is properly tracked");
 
@@ -579,27 +579,25 @@ void TestHostAddressChange(void)
     VerifyOrQuit(StringEndsWith(peer->GetHostName(), node2.Get<Mac::Mac>().GetExtAddress().ToString().AsCString()));
     VerifyOrQuit(peer->GetSockAddr().GetPort() == service.mPort);
 
-    VerifyOrQuit(peer->GetSockAddr().GetAddress() == node2.mMdns.mIfAddresses[0]);
+    VerifyOrQuit(peer->GetSockAddr().GetAddress() == node2.mInfraIf.GetLinkLocalAddress());
     VerifyOrQuit(peer->GetHostAddresses().GetLength() == 1);
-    VerifyOrQuit(peer->GetHostAddresses()[0] == node2.mMdns.mIfAddresses[0]);
+    VerifyOrQuit(peer->GetHostAddresses()[0] == node2.mInfraIf.GetLinkLocalAddress());
 
     VerifyOrQuit(peer->GetNext() == nullptr);
 
     // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
     Log("Update the advertised local host addresses on `node2`");
 
-    node2.mMdns.mIfAddresses.Clear();
+    node2.mInfraIf.RemoveAllAddresses();
 
     SuccessOrQuit(guaAddr.FromString("2001:cafe::4567"));
-    SuccessOrQuit(node2.mMdns.mIfAddresses.PushBack(guaAddr));
+    node2.mInfraIf.AddAddress(guaAddr);
 
     SuccessOrQuit(ulaAddr.FromString("fd00:abba::1234"));
-    SuccessOrQuit(node2.mMdns.mIfAddresses.PushBack(ulaAddr));
+    node2.mInfraIf.AddAddress(ulaAddr);
 
     SuccessOrQuit(linkLocalAddr.FromString("fe80::bd2c:a124"));
-    SuccessOrQuit(node2.mMdns.mIfAddresses.PushBack(linkLocalAddr));
+    node2.mInfraIf.AddAddress(linkLocalAddr);
-
-    node2.mMdns.SignalIfAddresses(node2.GetInstance());
 
     nexus.AdvanceTime(3 * 1000);
 
@@ -625,10 +623,10 @@ void TestHostAddressChange(void)
 
     for (const Ip6::Address &hostAddress : peer->GetHostAddresses())
     {
-        VerifyOrQuit(node2.mMdns.mIfAddresses.Contains(hostAddress));
+        VerifyOrQuit(node2.mInfraIf.HasAddress(hostAddress));
     }
 
-    for (const Ip6::Address &ifAddress : node2.mMdns.mIfAddresses)
+    for (const Ip6::Address &ifAddress : node2.mInfraIf.GetAddresses())
     {
         VerifyOrQuit(peer->GetHostAddresses().Contains(ifAddress));
     }
@@ -749,9 +747,9 @@ void TestMultiServiceSameHost(void)
         VerifyOrQuit(StringEndsWith(peerEntry.GetHostName(),
                                     multiServiceNode.Get<Mac::Mac>().GetExtAddress().ToString().AsCString()));
 
-        VerifyOrQuit(peerEntry.GetSockAddr().GetAddress() == multiServiceNode.mMdns.mIfAddresses[0]);
+        VerifyOrQuit(peerEntry.GetSockAddr().GetAddress() == multiServiceNode.mInfraIf.GetLinkLocalAddress());
         VerifyOrQuit(peerEntry.GetHostAddresses().GetLength() == 1);
-        VerifyOrQuit(peerEntry.GetHostAddresses()[0] == multiServiceNode.mMdns.mIfAddresses[0]);
+        VerifyOrQuit(peerEntry.GetHostAddresses()[0] == multiServiceNode.mInfraIf.GetLinkLocalAddress());
 
         for (const Dns::Multicast::Core::Service &service : services)
         {
@@ -791,9 +789,9 @@ void TestMultiServiceSameHost(void)
         VerifyOrQuit(StringEndsWith(peerEntry.GetHostName(),
                                     multiServiceNode.Get<Mac::Mac>().GetExtAddress().ToString().AsCString()));
 
-        VerifyOrQuit(peerEntry.GetSockAddr().GetAddress() == multiServiceNode.mMdns.mIfAddresses[0]);
+        VerifyOrQuit(peerEntry.GetSockAddr().GetAddress() == multiServiceNode.mInfraIf.GetLinkLocalAddress());
         VerifyOrQuit(peerEntry.GetHostAddresses().GetLength() == 1);
-        VerifyOrQuit(peerEntry.GetHostAddresses()[0] == multiServiceNode.mMdns.mIfAddresses[0]);
+        VerifyOrQuit(peerEntry.GetHostAddresses()[0] == multiServiceNode.mInfraIf.GetLinkLocalAddress());
 
         for (uint16_t index = 0; index < 2; index++)
         {
@@ -810,9 +808,7 @@ void TestMultiServiceSameHost(void)
     Log("Update the local host addresses on `multiServiceNode`");
 
     SuccessOrQuit(address.FromString("fd00:abba::1234"));
-    SuccessOrQuit(multiServiceNode.mMdns.mIfAddresses.PushBack(address));
+    multiServiceNode.mInfraIf.AddAddress(address);
-
-    multiServiceNode.mMdns.SignalIfAddresses(multiServiceNode.GetInstance());
 
     nexus.AdvanceTime(5 * 1000);
 
@@ -836,10 +832,10 @@ void TestMultiServiceSameHost(void)
         VerifyOrQuit(StringEndsWith(peerEntry.GetHostName(),
                                     multiServiceNode.Get<Mac::Mac>().GetExtAddress().ToString().AsCString()));
 
-        VerifyOrQuit(peerEntry.GetSockAddr().GetAddress() == multiServiceNode.mMdns.mIfAddresses[0]);
+        VerifyOrQuit(peerEntry.GetSockAddr().GetAddress() == multiServiceNode.mInfraIf.GetLinkLocalAddress());
         VerifyOrQuit(peerEntry.GetHostAddresses().GetLength() == 2);
-        VerifyOrQuit(peerEntry.GetHostAddresses()[0] == multiServiceNode.mMdns.mIfAddresses[0]);
+        VerifyOrQuit(peerEntry.GetHostAddresses()[0] == multiServiceNode.mInfraIf.GetLinkLocalAddress());
-        VerifyOrQuit(peerEntry.GetHostAddresses()[1] == multiServiceNode.mMdns.mIfAddresses[1]);
+        VerifyOrQuit(peerEntry.GetHostAddresses()[1] == multiServiceNode.mInfraIf.GetAddresses()[1]);
 
         for (uint16_t index = 0; index < 2; index++)
         {