[mdns] improve local host address logging (openthread#11651)

This commit refines the logging of local host address events in the
`Mdns` module.

Address update events signaled from the platform layer are now logged
at the `Debug` level instead of `Info`. This avoids excessive logging
from platform implementations that use periodic polling for address
monitoring.

Instead, after the events are processed, an `Info` level log is now
generated only if the address list has changed. This new log
specifies which addresses were added or removed. Additionally, the
format for IPv4 addresses (tracked as IPv4-mapped IPv6 addresses) is
updated to use the standard dotted-decimal notation, making the logs
easier to read.

Author: abtink

src/core/net/mdns.cpp

@@ -1566,7 +1566,7 @@ void Core::LocalHost::HandleAddressEvent(const Ip6::Address &aAddress, bool aAdd
     VerifyOrExit(Get<Core>().mIsEnabled);
     VerifyOrExit(aInfraIfIndex == Get<Core>().mInfraIfIndex);
 
-    LogInfo("Host address %s event: %s", aAddress.ToString().AsCString(), aAdded ? "added" : "removed");
+    LogDebg("Host address %s event: %s", aAddress.ToString().AsCString(), aAdded ? "add" : "remove");
 
     addrEvent = AddrEvent::Allocate(aAddress, aAdded);
     OT_ASSERT(addrEvent != nullptr);
@@ -1601,7 +1601,7 @@ void Core::LocalHost::HandleAddressRemoveAll(uint32_t aInfraIfIndex)
     mAddrEvents.Clear();
     mEventTimer.Stop();
 
-    LogInfo("Host address event: remove all");
+    LogDebg("Host address event: remove all");
 
     for (const Ip6::Address &address : mIp4Addresses)
     {
@@ -1645,6 +1645,10 @@ void Core::LocalHost::HandleEventTimer(void)
             {
                 SuccessOrAssert(addresses.PushBack(address));
             }
+            else
+            {
+                LogAddressChange(/* aAdded */ false, addrType, address);
+            }
         }
 
         // Next, add any new addresses for which we got an "added"
@@ -1660,6 +1664,7 @@ void Core::LocalHost::HandleEventTimer(void)
             if (addrEvent.mAdded && !addresses.Contains(addrEvent.mAddress))
             {
                 SuccessOrAssert(addresses.PushBack(addrEvent.mAddress));
+                LogAddressChange(/* aAdded */ true, addrType, addrEvent.mAddress);
             }
         }
     }
@@ -1670,6 +1675,23 @@ void Core::LocalHost::HandleEventTimer(void)
     mAddrEvents.Clear();
 }
 
+#if OT_SHOULD_LOG_AT(OT_LOG_LEVEL_INFO)
+void Core::LocalHost::LogAddressChange(bool aAdded, AddrType aAddrType, const Ip6::Address &aAddress) const
+{
+    Ip4::Address ip4Address;
+
+    if (aAddrType == kIp4AddrType)
+    {
+        SuccessOrAssert(ip4Address.ExtractFromIp4MappedIp6Address(aAddress));
+    }
+
+    LogInfo("%s host address %s", aAdded ? "Adding" : "Removing",
+            aAddrType == kIp4AddrType ? ip4Address.ToString().AsCString() : aAddress.ToString().AsCString());
+}
+#else
+void Core::LocalHost::LogAddressChange(bool, AddrType, const Ip6::Address &) const {}
+#endif
+
 //----------------------------------------------------------------------------------------------------------------------
 // Core::LocalHost::AddrEvent
 

src/core/net/mdns.hpp

@@ -1182,6 +1182,8 @@ class Core : public InstanceLocator, private NonCopyable
             bool         mAdded;
         };
 
+        void LogAddressChange(bool aAdded, AddrType aAddrType, const Ip6::Address &aAddress) const;
+
         using EventTimer = TimerMilliIn<Core, &Core::HandleLocalHostEventTimer>;
 
         Heap::String          mName;