[mle] introduce ComposeRloc() and ComposeAloc() (#13199)

This commit introduces `ComposeRloc()` and `ComposeAloc()` in the `Mle`
module and updates the codebase to use them.

These methods streamline the construction of Routing Locators and
Anycast Locators by automatically combining the Mesh-Local Prefix with
the provided RLOC16 or ALOC16. This centralizes address composition
logic within `Mle` instead of relying on manually formatting
`Ip6::Address` instances across various modules.

src/core/backbone_router/bbr_local.cpp

@@ -55,7 +55,6 @@ Local::Local(Instance &aInstance)
 {
     // Primary Backbone Router Aloc
     mBbrPrimaryAloc.InitAsThreadOriginMeshLocal();
-    mBbrPrimaryAloc.GetAddress().GetIid().InitAsLocator(Mle::Aloc16::ForPrimaryBackboneRouter());
 
     // All Network Backbone Routers Multicast Address.
     mAllNetworkBackboneRouters.Clear();
@@ -214,7 +213,7 @@ void Local::SetState(State aState)
     if (aState == kStatePrimary)
     {
         // Add Primary Backbone Router ALOC for Primary Backbone Router.
-        mBbrPrimaryAloc.GetAddress().SetPrefix(Get<Mle::Mle>().GetMeshLocalPrefix());
+        Get<Mle::Mle>().ComposeAloc(Mle::Aloc16::ForPrimaryBackboneRouter(), mBbrPrimaryAloc.GetAddress());
         Get<ThreadNetif>().AddUnicastAddress(mBbrPrimaryAloc);
     }
 

src/core/net/dhcp6_client.cpp

@@ -268,7 +268,7 @@ void Client::Solicit(uint16_t aRloc16)
 #if OPENTHREAD_ENABLE_DHCP6_MULTICAST_SOLICIT
     messageInfo.SetPeerAddr(Ip6::Address::GetRealmLocalAllRoutersMulticast());
 #else
-    messageInfo.GetPeerAddr().InitAsRoutingLocator(Get<Mle::Mle>().GetMeshLocalPrefix(), aRloc16);
+    Get<Mle::Mle>().ComposeRloc(aRloc16, messageInfo.GetPeerAddr());
 #endif
     messageInfo.SetSockAddr(Get<Mle::Mle>().GetMeshLocalRloc());
     messageInfo.mPeerPort = kDhcpServerPort;

src/core/net/dhcp6_server.cpp

@@ -164,7 +164,8 @@ void Server::AddPrefixAgent(const Ip6::Prefix &aIp6Prefix, uint8_t aContextId)
 
     VerifyOrExit(newEntry != nullptr, error = kErrorNoBufs);
 
-    newEntry->Set(aIp6Prefix, Get<Mle::Mle>().GetMeshLocalPrefix(), aContextId);
+    newEntry->SetPrefix(aIp6Prefix);
+    newEntry->ComposeAloc(GetInstance(), aContextId);
     Get<ThreadNetif>().AddUnicastAddress(newEntry->GetAloc());
     mPrefixAgentsCount++;
 
@@ -411,6 +412,12 @@ exit:
     return error;
 }
 
+void Server::PrefixAgent::ComposeAloc(Instance &aInstance, uint8_t aContextId)
+{
+    mAloc.InitAsThreadOriginMeshLocal();
+    aInstance.Get<Mle::Mle>().ComposeAloc((Ip6::Address::kAloc16Mask << 8) + aContextId, mAloc.GetAddress());
+}
+
 } // namespace Dhcp6
 } // namespace ot
 

src/core/net/dhcp6_server.hpp

@@ -141,20 +141,19 @@ private:
         }
 
         /**
-         * Sets the ALOC.
+         * Sets the IPv6 prefix.
          *
-         * @param[in]  aPrefix           The IPv6 prefix.
+         * @param[in] aPrefix  The IPv6 prefix.
-         * @param[in]  aMeshLocalPrefix  The Mesh Local Prefix.
+         */
+        void SetPrefix(const Ip6::Prefix &aPrefix) { mPrefix = aPrefix; }
+
+        /**
+         * Composes the ALOC address.
+         *
+         * @param[in]  aInstance         The OpenThread instance.
          * @param[in]  aContextId        The 6LoWPAN Context ID.
          */
-        void Set(const Ip6::Prefix &aPrefix, const Ip6::NetworkPrefix &aMeshLocalPrefix, uint8_t aContextId)
+        void ComposeAloc(Instance &aInstance, uint8_t aContextId);
-        {
-            mPrefix = aPrefix;
-
-            mAloc.InitAsThreadOrigin();
-            mAloc.GetAddress().InitAsAnycastLocator(aMeshLocalPrefix, (Ip6::Address::kAloc16Mask << 8) + aContextId);
-            mAloc.mMeshLocal = true;
-        }
 
     private:
         Ip6::Netif::UnicastAddress mAloc;

src/core/net/nd_agent.cpp

@@ -102,9 +102,8 @@ void Agent::UpdateService(void)
         {
             uint16_t aloc16 = Mle::Aloc16::FromNdAgentContextId(lowpanContext.GetContextId());
 
-            mAloc.InitAsThreadOrigin();
+            mAloc.InitAsThreadOriginMeshLocal();
-            mAloc.GetAddress().InitAsAnycastLocator(Get<Mle::Mle>().GetMeshLocalPrefix(), aloc16);
+            Get<Mle::Mle>().ComposeAloc(aloc16, mAloc.GetAddress());
-            mAloc.mMeshLocal = true;
             Get<ThreadNetif>().AddUnicastAddress(mAloc);
             ExitNow();
         }

src/core/thread/address_resolver.cpp

@@ -776,7 +776,7 @@ template <> void AddressResolver::HandleTmf<kUriAddressError>(Coap::Msg &aMsg)
 
             if (child.RemoveIp6Address(target) == kErrorNone)
             {
-                destination.InitAsRoutingLocator(Get<Mle::Mle>().GetMeshLocalPrefix(), child.GetRloc16());
+                Get<Mle::Mle>().ComposeRloc(child.GetRloc16(), destination);
 
                 SendAddressError(target, meshLocalIid, destination);
                 ExitNow();

src/core/thread/mesh_forwarder_ftd.cpp

@@ -536,7 +536,7 @@ void MeshForwarder::SendDestinationUnreachable(uint16_t aMeshSource, const Ip6::
 {
     Ip6::MessageInfo messageInfo;
 
-    messageInfo.GetPeerAddr().InitAsRoutingLocator(Get<Mle::Mle>().GetMeshLocalPrefix(), aMeshSource);
+    Get<Mle::Mle>().ComposeRloc(aMeshSource, messageInfo.GetPeerAddr());
 
     IgnoreError(Get<Ip6::Icmp>().SendError(Ip6::Icmp6Header::kTypeDstUnreach, Ip6::Icmp6Header::kCodeDstUnreachNoRoute,
                                            messageInfo, aIp6Headers));

src/core/thread/mle.cpp

@@ -848,7 +848,7 @@ void Mle::SetRloc16(uint16_t aRloc16)
         // We can always call `AddUnicastAddress(mMeshLocat16)` and if
         // the address is already added, it will perform no action.
 
-        mMeshLocalRloc.GetAddress().GetIid().SetLocator(aRloc16);
+        ComposeRloc(aRloc16, mMeshLocalRloc.GetAddress());
         Get<ThreadNetif>().AddUnicastAddress(mMeshLocalRloc);
 #if OPENTHREAD_FTD
         Get<AddressResolver>().RestartAddressQueries();
@@ -887,24 +887,23 @@ void Mle::SetLeaderData(uint32_t aPartitionId, uint8_t aWeighting, uint8_t aLead
     mLeaderData.SetLeaderRouterId(aLeaderRouterId);
 }
 
-void Mle::ComposeLeaderRloc(Ip6::Address &aAddress) const
+void Mle::ComposeRloc(uint16_t aRloc16, Ip6::Address &aAddress) const
 {
-    aAddress.InitAsRoutingLocator(mMeshLocalPrefix, GetLeaderRloc16());
+    aAddress.InitAsRoutingLocator(mMeshLocalPrefix, aRloc16);
 }
 
-void Mle::ComposeLeaderAloc(Ip6::Address &aAddress) const
+void Mle::ComposeLeaderRloc(Ip6::Address &aAddress) const { ComposeRloc(GetLeaderRloc16(), aAddress); }
-{
+
-    aAddress.InitAsAnycastLocator(mMeshLocalPrefix, Aloc16::ForLeader());
+void Mle::ComposeLeaderAloc(Ip6::Address &aAddress) const { ComposeAloc(Aloc16::ForLeader(), aAddress); }
-}
 
 void Mle::ComposeCommissionerAloc(uint16_t aSessionId, Ip6::Address &aAddress) const
 {
-    aAddress.InitAsAnycastLocator(mMeshLocalPrefix, Aloc16::FromCommissionerSessionId(aSessionId));
+    ComposeAloc(Aloc16::FromCommissionerSessionId(aSessionId), aAddress);
 }
 
 void Mle::ComposeServiceAloc(uint8_t aServiceId, Ip6::Address &aAddress) const
 {
-    aAddress.InitAsAnycastLocator(mMeshLocalPrefix, Aloc16::FromServiceId(aServiceId));
+    ComposeAloc(Aloc16::FromServiceId(aServiceId), aAddress);
 }
 
 const LeaderData &Mle::GetLeaderData(void)
@@ -2676,7 +2675,7 @@ void Mle::InformPreviousParent(void)
     SuccessOrExit(error = message->SetLength(0));
 
     messageInfo.SetSockAddr(GetMeshLocalEid());
-    messageInfo.GetPeerAddr().InitAsRoutingLocator(mMeshLocalPrefix, mPreviousParentRloc);
+    ComposeRloc(mPreviousParentRloc, messageInfo.GetPeerAddr());
 
     SuccessOrExit(error = Get<Ip6::Ip6>().SendDatagram(*message, messageInfo, Ip6::kProtoNone));
 

src/core/thread/mle.hpp

@@ -565,6 +565,22 @@ public:
      */
     uint16_t GetLeaderRloc16(void) const { return Rloc16FromRouterId(GetLeaderId()); }
 
+    /**
+     * Composes a Routing Locator (RLOC) address for a given RLOC16.
+     *
+     * @param[in]   aRloc16   The RLOC16 value.
+     * @param[out]  aAddress  A reference to an address to return the RLOC.
+     */
+    void ComposeRloc(uint16_t aRloc16, Ip6::Address &aAddress) const;
+
+    /**
+     * Composes an Anycast Locator (ALOC) address for a given ALOC16.
+     *
+     * @param[in]   aAloc16   The ALOC16 value.
+     * @param[out]  aAddress  A reference to an address to return the ALOC.
+     */
+    void ComposeAloc(uint16_t aAloc16, Ip6::Address &aAddress) const { ComposeRloc(aAloc16, aAddress); }
+
     /**
      * Composes the Leader's RLOC.
      *

src/core/thread/mlr_manager.cpp

@@ -532,8 +532,7 @@ Error Manager::SendMessage(const Ip6::Address         *aAddresses,
     }
     else
     {
-        destAddr.InitAsRoutingLocator(Get<Mle::Mle>().GetMeshLocalPrefix(),
+        Get<Mle::Mle>().ComposeRloc(Get<BackboneRouter::Leader>().GetServer16(), destAddr);
-                                      Get<BackboneRouter::Leader>().GetServer16());
     }
 
     error = Get<Tmf::Agent>().SendMessageTo(*message, destAddr, aResponseHandler, this);

src/core/thread/network_data_service.cpp

@@ -158,8 +158,7 @@ Error Iterator::GetNextDnsSrpUnicastInfo(DnsSrpUnicastType aType, DnsSrpUnicastI
                 // contains a port number and use the RLOC as the
                 // IPv6 address.
 
-                aInfo.mSockAddr.GetAddress().InitAsRoutingLocator(Get<Mle::Mle>().GetMeshLocalPrefix(),
+                Get<Mle::Mle>().ComposeRloc(mServerSubTlv->GetServer16(), aInfo.mSockAddr.GetAddress());
-                                                                  mServerSubTlv->GetServer16());
                 aInfo.mSockAddr.SetPort(BigEndian::ReadUint16(mServerSubTlv->GetServerData()));
                 aInfo.mVersion = 0;
                 ExitNow();

src/core/thread/tmf.cpp

@@ -247,7 +247,7 @@ Error Agent::SendMessageToRloc(Message &aMessage, uint16_t aRloc16, ResponseHand
 {
     Ip6::MessageInfo messageInfo;
 
-    messageInfo.GetPeerAddr().InitAsRoutingLocator(Get<Mle::Mle>().GetMeshLocalPrefix(), aRloc16);
+    Get<Mle::Mle>().ComposeRloc(aRloc16, messageInfo.GetPeerAddr());
     PrepareMessageInfo(messageInfo);
 
     return SendMessage(aMessage, messageInfo, aHandler, aContext);

src/core/utils/mesh_diag.cpp

@@ -99,7 +99,7 @@ Error MeshDiag::DiscoverTopology(const DiscoverConfig &aConfig, DiscoverCallback
             continue;
         }
 
-        destination.InitAsRoutingLocator(Get<Mle::Mle>().GetMeshLocalPrefix(), Mle::Rloc16FromRouterId(routerId));
+        Get<Mle::Mle>().ComposeRloc(Mle::Rloc16FromRouterId(routerId), destination);
 
         SuccessOrExit(error = Get<Client>().SendCommand(kUriDiagnosticGetRequest, Message::kPriorityLow, destination,
                                                         tlvs, tlvsLength, HandleDiagGetResponse, this));
@@ -165,7 +165,7 @@ Error MeshDiag::SendQuery(uint16_t aRloc16, const uint8_t *aTlvs, uint8_t aTlvsL
     VerifyOrExit(Mle::IsRouterRloc16(aRloc16), error = kErrorInvalidArgs);
     VerifyOrExit(Get<RouterTable>().IsAllocated(Mle::RouterIdFromRloc16(aRloc16)), error = kErrorNotFound);
 
-    destination.InitAsRoutingLocator(Get<Mle::Mle>().GetMeshLocalPrefix(), aRloc16);
+    Get<Mle::Mle>().ComposeRloc(aRloc16, destination);
 
     SuccessOrExit(error = Get<Client>().SendCommand(kUriDiagnosticGetQuery, Message::kPriorityNormal, destination,
                                                     aTlvs, aTlvsLength));

tests/nexus/test_pbbr_aloc.cpp

@@ -91,8 +91,7 @@ void TestPbbrAloc(void)
     nexus.SendAndVerifyEchoRequest(router, aloc);
 
     // 2. PBBR ALOC
-    aloc.SetPrefix(leader.Get<Mle::Mle>().GetMeshLocalPrefix());
+    leader.Get<Mle::Mle>().ComposeAloc(Mle::Aloc16::ForPrimaryBackboneRouter(), aloc);
-    aloc.GetIid().InitAsLocator(Mle::Aloc16::ForPrimaryBackboneRouter());
     Log("Pinging PBBR ALOC %s from ROUTER", aloc.ToString().AsCString());
     nexus.SendAndVerifyEchoRequest(router, aloc);
 

tests/nexus/test_service.cpp

@@ -110,8 +110,8 @@ void TestService(void)
     Ip6::Address aloc0;
     Ip6::Address aloc1;
 
-    aloc0.InitAsAnycastLocator(leader.Get<Mle::Mle>().GetMeshLocalPrefix(), Mle::Aloc16::FromServiceId(0));
+    leader.Get<Mle::Mle>().ComposeServiceAloc(0, aloc0);
-    aloc1.InitAsAnycastLocator(leader.Get<Mle::Mle>().GetMeshLocalPrefix(), Mle::Aloc16::FromServiceId(1));
+    leader.Get<Mle::Mle>().ComposeServiceAloc(1, aloc1);
 
     // Initial check: no ALOCs
     for (Node &node : nexus.GetNodes())