Fix concurrent mDNS resolution by verifying requested hostname

- libsrc/mdns/MdnsBrowser.cpp:119-170 now keeps each resolver self-contained: the resolver’s resolved signal
  is handled locally (no shared isAddressResolved signal), link‑local results are ignored on the spot, and the
  completion signal now carries the hostname so concurrent lookups can’t bleed into one another.
- include/mdns/MdnsBrowser.h:62-112 reflects the slimmer API—removed the unused slot/signal and updated
  isFirstAddressResolved to emit both hostname and address.
- include/utils/NetUtils.h:109-146 listens for the hostname-tagged completion and ignores unrelated emissions, so
  every resolveMDnsHostToAddress call exits only when its own hostname was resolved.

Courtesy of OpenAI Codex ;)

This fixes #1906

Author: discordianfish

CHANGELOG.md

@@ -44,6 +44,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
   - LED-device updates queue up and let Hyperion crash (#1887)
   - The color of the backlight threshold is green, not white/gray (#1899)
   - Install - Ubuntu 25.10 unable to install due to libcec package (#1934)
+  - Fix concurrent mDNS resolution (#1906)
 
 ---
 
@@ -61,7 +62,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - **Fixes:**
   - WebUI unreachable via IPv6 (#1871)
   - Align install_pr script working with default Qt6 builds & show authentication failures (#1871)
-  
+
 - **Build:**
     - Added Debian Trixie to PR-builds for early testing
 

include/mdns/MdnsBrowser.h

@@ -17,6 +17,7 @@
 #include <QByteArray>
 #include <QMap>
 #include <QJsonArray>
+#include <QString>
 #include <QSharedPointer>
 #include <QScopedPointer>
 
@@ -88,8 +89,7 @@ public slots:
 	 */
 	void serviceRemoved(const QMdnsEngine::Service& service);
 
-	void isAddressResolved(QHostAddress address);
-	void isFirstAddressResolved(QHostAddress address);
+	void isFirstAddressResolved(QString hostname, QHostAddress address);
 
 	void isServiceRecordResolved(QMdnsEngine::Record serviceRecord) const;
 
@@ -101,8 +101,6 @@ private slots:
 	void onServiceUpdated(const QMdnsEngine::Service& service);
 	void onServiceRemoved(const QMdnsEngine::Service& service);
 
-	void onHostNameResolved(const QHostAddress& address);
-
 private:
 	/// The logger instance for mDNS-Service
 	QSharedPointer<Logger> _log;

include/utils/NetUtils.h

@@ -118,8 +118,15 @@ inline bool resolveMDnsHostToAddress(QSharedPointer<Logger> log, const QString&
 			QEventLoop loop;
 
 			// Connect the signal to capture the resolved address
-			QObject::connect(browser, &MdnsBrowser::isFirstAddressResolved, &loop, [&](QHostAddress addr) {
-				hostAddress = std::move(addr);
+			QString const requestedHostname = hostname;
+			QObject::connect(browser, &MdnsBrowser::isFirstAddressResolved, &loop,
+							 [&, requestedHostname](const QString& resolvedHostname, const QHostAddress& addr) {
+				if (resolvedHostname.compare(requestedHostname, Qt::CaseInsensitive) != 0)
+				{
+					return;
+				}
+
+				hostAddress = addr;
 				loop.quit();
 			});
 

libsrc/mdns/MdnsBrowser.cpp

@@ -116,21 +116,6 @@ void MdnsBrowser::onServiceRemoved(const QMdnsEngine::Service& service)
 	emit serviceRemoved(service);
 }
 
-void MdnsBrowser::onHostNameResolved(const QHostAddress& address)
-{
-	DebugIf(verboseBrowser, _log, "for address [%s], Thread: %s", QSTRING_CSTR(address.toString()), QSTRING_CSTR(QThread::currentThread()->objectName()));
-
-	// Do not publish link local addresses
-#if (QT_VERSION >= QT_VERSION_CHECK(5, 11, 0))
-	if (!address.isLinkLocal())
-#else
-	if (!address.toString().startsWith("fe80"))
-#endif
-	{
-		emit isAddressResolved(address);
-	}
-}
-
 void MdnsBrowser::resolveFirstAddress(QSharedPointer<Logger> log, const QString& hostname, std::chrono::milliseconds timeout)
 {
 	qRegisterMetaType<QMdnsEngine::Message>("Message");
@@ -140,24 +125,28 @@ void MdnsBrowser::resolveFirstAddress(QSharedPointer<Logger> log, const QString&
 	if (hostname.endsWith(".local") || hostname.endsWith(".local."))
 	{
 		QMdnsEngine::Resolver const resolver (_server.get(), hostname.toUtf8(), _cache.get());
-		connect(&resolver, &QMdnsEngine::Resolver::resolved, this, &MdnsBrowser::onHostNameResolved);
 
 		DebugIf(verboseBrowser, log, "Wait for resolver on hostname [%s]", QSTRING_CSTR(hostname));
 
 		QEventLoop loop;
 		QTimer timer;
 
 		timer.setSingleShot(true);
-		connect(&timer, &QTimer::timeout, this, [&loop]() {
-			loop.quit();  // Stop waiting if timeout occurs
-		});
+		connect(&timer, &QTimer::timeout, &loop, &QEventLoop::quit);
+
+		connect(&resolver, &QMdnsEngine::Resolver::resolved, &loop, [ &loop, &resolvedAddress ](const QHostAddress& address) {
+			// Ignore link-local addresses
+#if (QT_VERSION >= QT_VERSION_CHECK(5, 11, 0))
+			if (address.isLinkLocal())
+#else
+			if (address.toString().startsWith("fe80"))
+#endif
+			{
+				return;
+			}
 
-		std::unique_ptr<QObject> context{new QObject};
-		QObject* pcontext = context.get();
-		connect(this, &MdnsBrowser::isAddressResolved, pcontext, [ &loop, &resolvedAddress, context = std::move(context)](const QHostAddress &address) mutable {
 			resolvedAddress = address;
 			loop.quit();
-			context.reset();
 		});
 
 		timer.start(timeout);
@@ -177,7 +166,7 @@ void MdnsBrowser::resolveFirstAddress(QSharedPointer<Logger> log, const QString&
 		Error(log, "Hostname [%s] is not an mDNS hostname.", QSTRING_CSTR(hostname));
 	}
 
-	emit isFirstAddressResolved(resolvedAddress);
+	emit isFirstAddressResolved(hostname, resolvedAddress);
 }
 
 void MdnsBrowser::resolveServiceInstance(const QByteArray& serviceInstance, const std::chrono::milliseconds waitTime) const