From cb90930632486d725c3a36a3d8499edb5c9de91b Mon Sep 17 00:00:00 2001
From: Abtin Keshavarzian <abtink@google.com>
Date: Mon, 30 Jun 2025 14:41:10 -0700
Subject: [PATCH] [mdns] improve local host address logging (#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.
---
 src/core/net/mdns.cpp | 26 ++++++++++++++++++++++++--
 src/core/net/mdns.hpp |  2 ++
 2 files changed, 26 insertions(+), 2 deletions(-)

diff --git a/src/core/net/mdns.cpp b/src/core/net/mdns.cpp
index 4f2e858be..e5973072b 100644
--- a/src/core/net/mdns.cpp
+++ b/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 @@ exit:
     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
 
diff --git a/src/core/net/mdns.hpp b/src/core/net/mdns.hpp
index 13d5eaf88..def39fa30 100644
--- a/src/core/net/mdns.hpp
+++ b/src/core/net/mdns.hpp
@@ -1182,6 +1182,8 @@ private:
             bool         mAdded;
         };
 
+        void LogAddressChange(bool aAdded, AddrType aAddrType, const Ip6::Address &aAddress) const;
+
         using EventTimer = TimerMilliIn<Core, &Core::HandleLocalHostEventTimer>;
 
         Heap::String          mName;