[ip] make mesh-local addresses non-preferred (#6532)

This commit marks anycast addresses and mesh-local addresses as
IPv6 deprecated addresses.

include/openthread/ip6.h

@@ -427,7 +427,7 @@ typedef struct otIp6AddressInfo
     const otIp6Address *mAddress;       ///< A pointer to the IPv6 address.
     uint8_t             mPrefixLength;  ///< The prefix length of mAddress if it is a unicast address.
     uint8_t             mScope : 4;     ///< The scope of this address.
-    bool                mIsAnycast : 1; ///< Whether this is an anycast address.
+    bool                mPreferred : 1; ///< Whether this is a preferred address.
 } otIp6AddressInfo;
 
 /**

src/core/net/netif.cpp

@@ -45,12 +45,12 @@ namespace Ip6 {
 class AddressInfo : public otIp6AddressInfo
 {
 public:
-    AddressInfo(const NetifUnicastAddress &aAddress, Instance &aInstance)
+    explicit AddressInfo(const NetifUnicastAddress &aAddress)
     {
         mAddress      = &aAddress.mAddress;
         mPrefixLength = aAddress.mPrefixLength;
         mScope        = aAddress.GetScope();
-        mIsAnycast    = aInstance.Get<Mle::MleRouter>().IsAnycastLocator(aAddress.GetAddress());
+        mPreferred    = aAddress.mPreferred;
     }
 
     explicit AddressInfo(const NetifMulticastAddress &aAddress)
@@ -58,7 +58,7 @@ public:
         mAddress      = &aAddress.GetAddress();
         mPrefixLength = kMulticastPrefixLength;
         mScope        = aAddress.GetAddress().GetScope();
-        mIsAnycast    = false;
+        mPreferred    = false;
     }
 
 private:
@@ -439,7 +439,7 @@ void Netif::AddUnicastAddress(NetifUnicastAddress &aAddress)
     VerifyOrExit(mAddressCallback != nullptr);
 
     {
-        AddressInfo addressInfo(aAddress, GetInstance());
+        AddressInfo addressInfo(aAddress);
 
         mAddressCallback(&addressInfo,
                          /* IsAdded */ true, mAddressCallbackContext);
@@ -457,7 +457,7 @@ void Netif::RemoveUnicastAddress(const NetifUnicastAddress &aAddress)
 
     VerifyOrExit(mAddressCallback != nullptr);
     {
-        AddressInfo addressInfo(aAddress, GetInstance());
+        AddressInfo addressInfo(aAddress);
 
         mAddressCallback(&addressInfo, /* IsAdded */ false, mAddressCallbackContext);
     }
@@ -543,12 +543,12 @@ bool Netif::IsUnicastAddressExternal(const NetifUnicastAddress &aAddress) const
     return mExtUnicastAddressPool.IsPoolEntry(aAddress);
 }
 
-void NetifUnicastAddress::InitAsThreadOrigin(void)
+void NetifUnicastAddress::InitAsThreadOrigin(bool aPreferred)
 {
     Clear();
     mPrefixLength  = NetworkPrefix::kLength;
     mAddressOrigin = OT_ADDRESS_ORIGIN_THREAD;
-    mPreferred     = true;
+    mPreferred     = aPreferred;
     mValid         = true;
 }
 

src/core/net/netif.hpp

@@ -80,12 +80,14 @@ public:
      * This method clears and initializes the unicast address as a preferred, valid, thread-origin address with 64-bit
      * prefix length.
      *
+     * @param[in]   aPreferred  Whether to initialize as a preferred address.
+     *
      */
-    void InitAsThreadOrigin(void);
+    void InitAsThreadOrigin(bool aPreferred = false);
 
     /**
-     * This method clears and initializes the unicast address as a preferred, valid, thread-origin, realm-local scope
-     * (overridden) address with 64-bit prefix length.
+     * This method clears and initializes the unicast address as a valid (but not preferred), thread-origin, realm-local
+     * scope (overridden) address with 64-bit prefix length.
      *
      */
     void InitAsThreadOriginRealmLocalScope(void);

src/core/thread/mle.cpp

@@ -124,7 +124,7 @@ Mle::Mle(Instance &aInstance)
     mParentCandidate.Clear();
     ResetCounters();
 
-    mLinkLocal64.InitAsThreadOrigin();
+    mLinkLocal64.InitAsThreadOrigin(/* aPreferred */ true);
     mLinkLocal64.GetAddress().SetToLinkLocalAddress(Get<Mac::Mac>().GetExtAddress());
 
     mLeaderAloc.InitAsThreadOriginRealmLocalScope();

src/posix/platform/netif.cpp

@@ -344,7 +344,7 @@ static void UpdateUnicastLinux(const otIp6AddressInfo &aAddressInfo, bool aIsAdd
 
     req.nh.nlmsg_len = NLMSG_ALIGN(req.nh.nlmsg_len) + rta->rta_len;
 
-    if (aAddressInfo.mIsAnycast)
+    if (!aAddressInfo.mPreferred)
     {
         struct ifa_cacheinfo cacheinfo;
 
@@ -402,7 +402,7 @@ static void UpdateUnicast(otInstance *aInstance, const otIp6AddressInfo &aAddres
 
 #if defined(__APPLE__)
         ifr6.ifra_lifetime.ia6t_expire    = ND6_INFINITE_LIFETIME;
-        ifr6.ifra_lifetime.ia6t_preferred = ND6_INFINITE_LIFETIME;
+        ifr6.ifra_lifetime.ia6t_preferred = (aAddressInfo.mPreferred ? ND6_INFINITE_LIFETIME : 0);
 #endif
 
         rval = ioctl(sIpFd, aIsAdded ? SIOCAIFADDR_IN6 : SIOCDIFADDR_IN6, &ifr6);