FIX(client, server): Load native mDNS/DNS-SD symbols at runtime

This change:
- Fixes binaries failing to start on versions of Windows where dnsapi.dll doesn't export the symbols we need.
- Allows us to use the native API in x86 builds.
See https://developercommunity.visualstudio.com/content/problem/1191345/some-dns-api-functions-cause-lnk2019-errors-in-32.html for more info.

src/mumble/Zeroconf.cpp

@@ -5,39 +5,36 @@
 
 #include "Zeroconf.h"
 
-#define SYMBOL_EXISTS(symbol) (GetProcAddress(handle, symbol))
+#define GET_SYMBOL(symbol) (symbol = reinterpret_cast< decltype(symbol) >(GetProcAddress(handle, #symbol)))
 
 Zeroconf::Zeroconf() : m_ok(false) {
 	qRegisterMetaType< uint16_t >("uint16_t");
 	qRegisterMetaType< BonjourRecord >("BonjourRecord");
 	qRegisterMetaType< QList< BonjourRecord > >("QList<BonjourRecord>");
-#ifdef Q_OS_WIN64
-	static bool winDnsUnavailable = false;
-	if (!winDnsUnavailable) {
-		auto handle = GetModuleHandle(L"dnsapi.dll");
-		if (handle) {
-			if (SYMBOL_EXISTS("DnsServiceBrowse") && SYMBOL_EXISTS("DnsServiceBrowseCancel")
-				&& SYMBOL_EXISTS("DnsServiceResolve") && SYMBOL_EXISTS("DnsServiceResolveCancel")
-				&& SYMBOL_EXISTS("DnsServiceFreeInstance")) {
-				m_ok = true;
-				return;
-			}
-		}
+#ifdef Q_OS_WIN
+	auto handle = GetModuleHandle(L"dnsapi.dll");
+	if (handle) {
+		GET_SYMBOL(DnsServiceBrowse);
+		GET_SYMBOL(DnsServiceBrowseCancel);
+		GET_SYMBOL(DnsServiceResolve);
+		GET_SYMBOL(DnsServiceResolveCancel);
+		GET_SYMBOL(DnsServiceFreeInstance);
 
-		winDnsUnavailable = true;
-		qWarning("Zeroconf: Native mDNS/DNS-SD API not available, falling back to third-party API");
-	}
-
-	static bool dnssdLoadFailed = false;
-	if (!dnssdLoadFailed) {
-		auto handle = LoadLibrary(L"dnssd.DLL");
-		if (!handle) {
-			dnssdLoadFailed = true;
-			qWarning("Zeroconf: Failed to load dnssd.dll, assuming third-party API is not available");
+		if (DnsServiceBrowse && DnsServiceBrowseCancel && DnsServiceResolve && DnsServiceResolveCancel
+			&& DnsServiceFreeInstance) {
+			m_ok = true;
 			return;
 		}
-		FreeLibrary(handle);
 	}
+
+	qWarning("Zeroconf: Native mDNS/DNS-SD API not available, falling back to third-party API");
+
+	handle = LoadLibrary(L"dnssd.dll");
+	if (!handle) {
+		qWarning("Zeroconf: Failed to load dnssd.dll, assuming third-party API is not available");
+		return;
+	}
+	FreeLibrary(handle);
 #endif
 	resetHelperBrowser();
 	resetHelperResolver();
@@ -80,7 +77,7 @@ bool Zeroconf::startBrowser(const QString &serviceType) {
 		m_helperBrowser->browseForServiceType(serviceType);
 		return true;
 	}
-#ifdef Q_OS_WIN64
+#ifdef Q_OS_WIN
 	const QString queryName = serviceType + QLatin1String(".local");
 
 	DNS_SERVICE_BROWSE_REQUEST request{};
@@ -110,7 +107,7 @@ bool Zeroconf::stopBrowser() {
 		resetHelperBrowser();
 		return true;
 	}
-#ifdef Q_OS_WIN64
+#ifdef Q_OS_WIN
 	if (m_cancelBrowser) {
 		const auto ret = DnsServiceBrowseCancel(m_cancelBrowser.get());
 		if (ret == ERROR_SUCCESS || ret == ERROR_CANCELLED) {
@@ -134,7 +131,7 @@ bool Zeroconf::startResolver(const BonjourRecord &record) {
 		m_helperResolver->resolveBonjourRecord(record);
 		return true;
 	}
-#ifdef Q_OS_WIN64
+#ifdef Q_OS_WIN
 	stopResolver(record);
 
 	auto qualifiedHostname = record.serviceName.toStdWString() + L"." + record.registeredType.toStdWString()
@@ -160,7 +157,7 @@ bool Zeroconf::startResolver(const BonjourRecord &record) {
 #endif
 	return false;
 }
-#ifdef Q_OS_WIN64
+#ifdef Q_OS_WIN
 bool Zeroconf::stopResolver(const BonjourRecord &record) {
 	if (!m_ok) {
 		return false;
@@ -200,7 +197,7 @@ bool Zeroconf::cleanupResolvers() {
 	}
 
 	auto result = true;
-#ifdef Q_OS_WIN64
+#ifdef Q_OS_WIN
 	for (auto i = 0; i < m_resolvers.size(); ++i) {
 		if (!stopResolver(m_resolvers[i])) {
 			result = false;
@@ -228,7 +225,7 @@ void Zeroconf::helperResolverError(const BonjourRecord record, const DNSServiceE
 	qWarning("Zeroconf: Third-party resolver API reports error %d", error);
 	emit resolveError(record);
 }
-#ifdef Q_OS_WIN64
+#ifdef Q_OS_WIN
 void WINAPI Zeroconf::callbackBrowseComplete(const DWORD status, void *context, DNS_RECORD *records) {
 	auto zeroconf = static_cast< Zeroconf * >(context);
 	zeroconf->m_cancelBrowser.reset();
@@ -283,9 +280,12 @@ void WINAPI Zeroconf::callbackBrowseComplete(const DWORD status, void *context,
 }
 
 void WINAPI Zeroconf::callbackResolveComplete(const DWORD status, void *context, DNS_SERVICE_INSTANCE *instance) {
+	auto resolver = static_cast< Resolver * >(context);
+	auto zeroconf = resolver->m_zeroconf;
+
 	if (status != ERROR_SUCCESS) {
 		if (instance) {
-			DnsServiceFreeInstance(instance);
+			zeroconf->DnsServiceFreeInstance(instance);
 		}
 
 		if (status != ERROR_CANCELLED) {
@@ -299,10 +299,8 @@ void WINAPI Zeroconf::callbackResolveComplete(const DWORD status, void *context,
 		return;
 	}
 
-	auto resolverContext = static_cast< Resolver * >(context);
-	emit resolverContext->m_zeroconf->recordResolved(resolverContext->m_record,
-													 QString::fromWCharArray(instance->pszHostName), instance->wPort);
+	emit zeroconf->recordResolved(resolver->m_record, QString::fromWCharArray(instance->pszHostName), instance->wPort);
 
-	DnsServiceFreeInstance(instance);
+	zeroconf->DnsServiceFreeInstance(instance);
 }
 #endif

src/mumble/Zeroconf.h

@@ -11,7 +11,7 @@
 
 #include <memory>
 
-#ifdef Q_OS_WIN64
+#ifdef Q_OS_WIN
 #	include <windns.h>
 #endif
 
@@ -20,7 +20,7 @@ private:
 	Q_OBJECT
 	Q_DISABLE_COPY(Zeroconf)
 protected:
-#ifdef Q_OS_WIN64
+#ifdef Q_OS_WIN
 	struct Resolver {
 		Zeroconf *m_zeroconf;
 		BonjourRecord m_record;
@@ -35,7 +35,7 @@ protected:
 	QList< BonjourRecord > m_records;
 	std::unique_ptr< BonjourServiceBrowser > m_helperBrowser;
 	std::unique_ptr< BonjourServiceResolver > m_helperResolver;
-#ifdef Q_OS_WIN64
+#ifdef Q_OS_WIN
 	QList< Resolver > m_resolvers;
 	std::unique_ptr< DNS_SERVICE_CANCEL > m_cancelBrowser;
 
@@ -51,7 +51,13 @@ protected:
 	void helperResolverRecordResolved(const BonjourRecord record, const QString hostname, const int port);
 	void helperBrowserError(const DNSServiceErrorType error) const;
 	void helperResolverError(const BonjourRecord record, const DNSServiceErrorType error);
-
+#ifdef Q_OS_WIN
+	DNS_STATUS(WINAPI *DnsServiceBrowse)(PDNS_SERVICE_BROWSE_REQUEST pRequest, PDNS_SERVICE_CANCEL pCancel);
+	DNS_STATUS(WINAPI *DnsServiceBrowseCancel)(PDNS_SERVICE_CANCEL pCancelHandle);
+	DNS_STATUS(WINAPI *DnsServiceResolve)(PDNS_SERVICE_RESOLVE_REQUEST pRequest, PDNS_SERVICE_CANCEL pCancel);
+	DNS_STATUS(WINAPI *DnsServiceResolveCancel)(PDNS_SERVICE_CANCEL pCancelHandle);
+	VOID(WINAPI *DnsServiceFreeInstance)(PDNS_SERVICE_INSTANCE pInstance);
+#endif
 public:
 	inline bool isOk() const { return m_ok; }
 	inline QList< BonjourRecord > currentRecords() const {
@@ -62,7 +68,7 @@ public:
 	bool stopBrowser();
 
 	bool startResolver(const BonjourRecord &record);
-#ifdef Q_OS_WIN64
+#ifdef Q_OS_WIN
 	bool stopResolver(const BonjourRecord &record);
 #endif
 	bool cleanupResolvers();

src/murmur/Zeroconf.cpp

@@ -5,37 +5,33 @@
 
 #include "Zeroconf.h"
 
-#define SYMBOL_EXISTS(symbol) (GetProcAddress(handle, symbol))
+#define GET_SYMBOL(symbol) (symbol = reinterpret_cast< decltype(symbol) >(GetProcAddress(handle, #symbol)))
 
 Zeroconf::Zeroconf() : m_ok(false) {
-#ifdef Q_OS_WIN64
-	static bool winDnsUnavailable = false;
-	if (!winDnsUnavailable) {
-		auto handle = GetModuleHandle(L"dnsapi.dll");
-		if (handle) {
-			if (SYMBOL_EXISTS("DnsServiceConstructInstance") && SYMBOL_EXISTS("DnsServiceFreeInstance")
-				&& SYMBOL_EXISTS("DnsServiceRegister") && SYMBOL_EXISTS("DnsServiceDeRegister")
-				&& SYMBOL_EXISTS("DnsServiceRegisterCancel")) {
-				m_ok = true;
-				return;
-			}
-		}
+#ifdef Q_OS_WIN
+	auto handle = GetModuleHandle(L"dnsapi.dll");
+	if (handle) {
+		GET_SYMBOL(DnsServiceConstructInstance);
+		GET_SYMBOL(DnsServiceFreeInstance);
+		GET_SYMBOL(DnsServiceRegister);
+		GET_SYMBOL(DnsServiceDeRegister);
+		GET_SYMBOL(DnsServiceRegisterCancel);
 
-		winDnsUnavailable = true;
-		qWarning("Zeroconf: Native mDNS/DNS-SD API not available, falling back to third-party API");
-	}
-
-	static bool dnssdLoadFailed = false;
-	if (!dnssdLoadFailed) {
-		auto handle = LoadLibrary(L"dnssd.DLL");
-		if (!handle) {
-			dnssdLoadFailed = true;
-			qWarning("Zeroconf: Failed to load dnssd.dll, assuming third-party API is not available");
+		if (DnsServiceConstructInstance && DnsServiceFreeInstance && DnsServiceRegister && DnsServiceDeRegister
+			&& DnsServiceRegisterCancel) {
+			m_ok = true;
 			return;
 		}
-
-		FreeLibrary(handle);
 	}
+
+	qWarning("Zeroconf: Native mDNS/DNS-SD API not available, falling back to third-party API");
+
+	handle = LoadLibrary(L"dnssd.dll");
+	if (!handle) {
+		qWarning("Zeroconf: Failed to load dnssd.dll, assuming third-party API is not available");
+		return;
+	}
+	FreeLibrary(handle);
 #endif
 	resetHelper();
 
@@ -64,7 +60,7 @@ bool Zeroconf::registerService(const BonjourRecord &record, const uint16_t port)
 		m_helper->registerService(record, port);
 		return true;
 	}
-#ifdef Q_OS_WIN64
+#ifdef Q_OS_WIN
 	DWORD size = 0;
 	GetComputerNameEx(ComputerNameDnsHostname, nullptr, &size);
 	std::vector< wchar_t > hostname(size);
@@ -118,7 +114,7 @@ bool Zeroconf::unregisterService() {
 		resetHelper();
 		return true;
 	}
-#ifdef Q_OS_WIN64
+#ifdef Q_OS_WIN
 	if (m_cancel) {
 		const auto ret = DnsServiceRegisterCancel(m_cancel.get());
 		if (ret == ERROR_SUCCESS || ret == ERROR_CANCELLED) {
@@ -142,17 +138,18 @@ bool Zeroconf::unregisterService() {
 void Zeroconf::helperError(const DNSServiceErrorType error) {
 	qWarning("Zeroconf: Third-party API reports error %d, service registration probably failed", error);
 }
-#ifdef Q_OS_WIN64
+#ifdef Q_OS_WIN
 void WINAPI Zeroconf::callbackRegisterComplete(const DWORD status, void *context, DNS_SERVICE_INSTANCE *instance) {
+	auto zeroconf = static_cast< Zeroconf * >(context);
+
 	if (instance) {
-		DnsServiceFreeInstance(instance);
+		zeroconf->DnsServiceFreeInstance(instance);
 	}
 
 	if (status == ERROR_CANCELLED) {
 		return;
 	}
 
-	auto zeroconf = static_cast< Zeroconf * >(context);
 	zeroconf->m_cancel.reset();
 
 	if (status != ERROR_SUCCESS) {

src/murmur/Zeroconf.h

@@ -10,7 +10,7 @@
 
 #include <memory>
 
-#ifdef Q_OS_WIN64
+#ifdef Q_OS_WIN
 #	include <windns.h>
 #endif
 
@@ -21,14 +21,22 @@ private:
 protected:
 	bool m_ok;
 	std::unique_ptr< BonjourServiceRegister > m_helper;
-#ifdef Q_OS_WIN64
+#ifdef Q_OS_WIN
 	std::unique_ptr< DNS_SERVICE_CANCEL > m_cancel;
 	std::unique_ptr< DNS_SERVICE_REGISTER_REQUEST > m_request;
 
 	static void WINAPI callbackRegisterComplete(const DWORD status, void *context, DNS_SERVICE_INSTANCE *instance);
 #endif
 	void helperError(const DNSServiceErrorType error);
-
+#ifdef Q_OS_WIN
+	PDNS_SERVICE_INSTANCE(WINAPI *DnsServiceConstructInstance)
+	(PCWSTR pServiceName, PCWSTR pHostName, PIP4_ADDRESS pIp4, PIP6_ADDRESS pIp6, WORD wPort, WORD wPriority,
+	 WORD wWeight, DWORD dwPropertiesCount, PCWSTR *keys, PCWSTR *values);
+	VOID(WINAPI *DnsServiceFreeInstance)(PDNS_SERVICE_INSTANCE pInstance);
+	DWORD(WINAPI *DnsServiceRegister)(PDNS_SERVICE_REGISTER_REQUEST pRequest, PDNS_SERVICE_CANCEL pCancel);
+	DWORD(WINAPI *DnsServiceDeRegister)(PDNS_SERVICE_REGISTER_REQUEST pRequest, PDNS_SERVICE_CANCEL pCancel);
+	DWORD(WINAPI *DnsServiceRegisterCancel)(PDNS_SERVICE_CANCEL pCancelHandle);
+#endif
 public:
 	inline bool isOk() const { return m_ok; }