Add notification for when the default route changes

4 files changed, 228 insertions, 1 deletions

diff --git a/windows/winnet/src/winnet/routemanager.cpp b/windows/winnet/src/winnet/routemanager.cpp
index 35aef395ba..c1e897b578 100644
--- a/windows/winnet/src/winnet/routemanager.cpp
+++ b/windows/winnet/src/winnet/routemanager.cpp
@@ -625,6 +625,31 @@ void RouteManager::deleteRoute(const Route &route)
 	m_routes.erase(record);
 }
 
+RouteManager::CallbackHandle RouteManager::registerDefaultRouteChangedCallback(DefaultRouteChangedCallback callback)
+{
+	LockType lock(m_defaultRouteCallbacksLock);
+
+	m_defaultRouteCallbacks.emplace_back(callback);
+
+	// Return raw address of record in list.
+	return &m_defaultRouteCallbacks.back();
+}
+
+void RouteManager::unregisterDefaultRouteChangedCallback(CallbackHandle handle)
+{
+	LockType lock(m_defaultRouteCallbacksLock);
+
+	for (auto it = m_defaultRouteCallbacks.begin(); it != m_defaultRouteCallbacks.end(); ++it)
+	{
+		// Match on raw address of record.
+		if (&*it == handle)
+		{
+			m_defaultRouteCallbacks.erase(it);
+			return;
+		}
+	}
+}
+
 std::list<RouteManager::RouteRecord>::iterator RouteManager::findRouteRecord(const Network &network)
 {
 	return std::find_if(m_routes.begin(), m_routes.end(), [&network](const auto &candidate)
@@ -930,4 +955,24 @@ std::wstring RouteManager::FormatRegisteredRoute(const RegisteredRoute &route)
 	return ss.str();
 }
 
+void RouteManager::notifyNewBestDefaultRoute(ADDRESS_FAMILY addressFamily, NET_LUID iface)
+{
+	LockType lock(m_defaultRouteCallbacksLock);
+
+	for (const auto &callback : m_defaultRouteCallbacks)
+	{
+		callback(DefaultRouteChangedEvent::Updated, addressFamily, iface);
+	}
+}
+
+void RouteManager::notifyNoDefaultRoutesExist(ADDRESS_FAMILY addressFamily)
+{
+	LockType lock(m_defaultRouteCallbacksLock);
+
+	for (const auto &callback : m_defaultRouteCallbacks)
+	{
+		callback(DefaultRouteChangedEvent::Removed, addressFamily, NET_LUID{ 0 });
+	}
+}
+
 }
diff --git a/windows/winnet/src/winnet/routemanager.h b/windows/winnet/src/winnet/routemanager.h
index 6161dcd62a..9ae007b757 100644
--- a/windows/winnet/src/winnet/routemanager.h
+++ b/windows/winnet/src/winnet/routemanager.h
@@ -13,6 +13,7 @@
 #include <ws2ipdef.h>
 #include <iphlpapi.h>
 #include <netioapi.h>
+#include <functional>
 
 // Custom header files below here.
 // So broken networking headers don't get confused and break the compilation.
@@ -149,6 +150,31 @@ public:
 	void deleteRoutes(const std::vector<Route> &routes);
 	void deleteRoute(const Route &route);
 
+	enum class DefaultRouteChangedEvent
+	{
+		// The best default route changed.
+		Updated,
+
+		// No default routes exist.
+		Removed,
+	};
+
+	using DefaultRouteChangedCallback = std::function<void
+	(
+		DefaultRouteChangedEvent eventType,
+
+		// Signals which IP family the event relates to.
+		ADDRESS_FAMILY addressFamily,
+
+		// For update events, signals the interface associated with the new best default route.
+		NET_LUID iface
+	)>;
+
+	using CallbackHandle = void*;
+
+	CallbackHandle registerDefaultRouteChangedCallback(DefaultRouteChangedCallback callback);
+	void unregisterDefaultRouteChangedCallback(CallbackHandle handle);
+
 private:
 
 	std::shared_ptr<common::logging::ILogSink> m_logSink;
@@ -169,9 +195,11 @@ private:
 	};
 
 	std::list<RouteRecord> m_routes;
-
 	std::recursive_mutex m_routesLock;
 
+	std::list<DefaultRouteChangedCallback> m_defaultRouteCallbacks;
+	std::recursive_mutex m_defaultRouteCallbacksLock;
+
 	// Find record based on destination and mask.
 	std::list<RouteRecord>::iterator findRouteRecord(const Network &network);
 
@@ -202,6 +230,9 @@ private:
 	void routeChangeCallback(MIB_IPFORWARD_ROW2 *row, MIB_NOTIFICATION_TYPE notificationType);
 
 	static std::wstring FormatRegisteredRoute(const RegisteredRoute &route);
+
+	void notifyNewBestDefaultRoute(ADDRESS_FAMILY addressFamily, NET_LUID iface);
+	void notifyNoDefaultRoutesExist(ADDRESS_FAMILY addressFamily);
 };
 
 }
diff --git a/windows/winnet/src/winnet/winnet.cpp b/windows/winnet/src/winnet/winnet.cpp
index 4240f6a706..d36a60fd90 100644
--- a/windows/winnet/src/winnet/winnet.cpp
+++ b/windows/winnet/src/winnet/winnet.cpp
@@ -520,6 +520,111 @@ WinNet_DeleteRoute(
 

 extern "C"

 WINNET_LINKAGE

+bool

+WINNET_API

+WinNet_RegisterDefaultRouteChangedCallback(

+	WinNetDefaultRouteChangedCallback callback,

+	void *context,

+	void **registrationHandle

+)

+{

+	if (nullptr == g_RouteManager)

+	{

+		return false;

+	}

+

+	try

+	{

+		auto forwarder = [callback, context]

+			(RouteManager::DefaultRouteChangedEvent eventType, ADDRESS_FAMILY addressFamily, NET_LUID iface)

+		{

+			WINNET_DEFAULT_ROUTE_CHANGED_EVENT_TYPE translatedType;

+

+			switch (eventType)

+			{

+				case RouteManager::DefaultRouteChangedEvent::Updated:

+				{

+					translatedType = WINNET_DEFAULT_ROUTE_CHANGED_EVENT_TYPE_UPDATED;

+					break;

+				}

+				case RouteManager::DefaultRouteChangedEvent::Removed:

+				{

+					translatedType = WINNET_DEFAULT_ROUTE_CHANGED_EVENT_TYPE_REMOVED;

+					break;

+				}

+				default:

+				{

+					throw std::runtime_error("Unexpected default-route-changed event type");

+				}

+			}

+

+			WINNET_IP_FAMILY translatedFamily;

+

+			switch (addressFamily)

+			{

+				case AF_INET:

+				{

+					translatedFamily = WINNET_IP_FAMILY_V4;

+					break;

+				}

+				case AF_INET6:

+				{

+					translatedFamily = WINNET_IP_FAMILY_V6;

+					break;

+				}

+				default:

+				{

+					throw std::runtime_error("Unexpected default-route-changed address family");

+				}

+			}

+

+			callback(translatedType, translatedFamily, iface.Value, context);

+		};

+

+		*registrationHandle = g_RouteManager->registerDefaultRouteChangedCallback(forwarder);

+

+		return true;

+	}

+	catch (const std::exception &err)

+	{

+		common::error::UnwindException(err, g_RouteManagerLogSink);

+		return false;

+	}

+	catch (...)

+	{

+		return false;

+	}

+}

+

+extern "C"

+WINNET_LINKAGE

+void

+WINNET_API

+WinNet_UnregisterDefaultRouteChangedCallback(

+	void *registrationHandle

+)

+{

+	if (nullptr == g_RouteManager)

+	{

+		return;

+	}

+

+	try

+	{

+		g_RouteManager->unregisterDefaultRouteChangedCallback(registrationHandle);

+	}

+	catch (const std::exception &err)

+	{

+		g_RouteManagerLogSink->error("Failed to unregister default-route-changed callback");

+		common::error::UnwindException(err, g_RouteManagerLogSink);

+	}

+	catch (...)

+	{

+	}

+}

+

+extern "C"

+WINNET_LINKAGE

 void

 WINNET_API

 WinNet_DeactivateRouteManager(

diff --git a/windows/winnet/src/winnet/winnet.h b/windows/winnet/src/winnet/winnet.h
index 7b4272fc72..c7a161c3d8 100644
--- a/windows/winnet/src/winnet/winnet.h
+++ b/windows/winnet/src/winnet/winnet.h
@@ -169,6 +169,52 @@ WinNet_DeleteRoute(
 	const WINNET_ROUTE *route
 );
 
+enum WINNET_DEFAULT_ROUTE_CHANGED_EVENT_TYPE
+{
+	// Best default route changed.
+	WINNET_DEFAULT_ROUTE_CHANGED_EVENT_TYPE_UPDATED = 0,
+
+	// No default routes exist.
+	WINNET_DEFAULT_ROUTE_CHANGED_EVENT_TYPE_REMOVED = 1,
+};
+
+enum WINNET_IP_FAMILY
+{
+	WINNET_IP_FAMILY_V4 = 0,
+	WINNET_IP_FAMILY_V6 = 1,
+};
+
+typedef void (WINNET_API *WinNetDefaultRouteChangedCallback)
+(
+	WINNET_DEFAULT_ROUTE_CHANGED_EVENT_TYPE eventType,
+
+	// Signals which IP family the event relates to.
+	WINNET_IP_FAMILY family,
+
+	// For update events, signals the interface associated with the new best default route.
+	uint64_t interfaceLuid,
+
+	void *context
+);
+
+extern "C"
+WINNET_LINKAGE
+bool
+WINNET_API
+WinNet_RegisterDefaultRouteChangedCallback(
+	WinNetDefaultRouteChangedCallback callback,
+	void *context,
+	void **registrationHandle
+);
+
+extern "C"
+WINNET_LINKAGE
+void
+WINNET_API
+WinNet_UnregisterDefaultRouteChangedCallback(
+	void *registrationHandle
+);
+
 extern "C"
 WINNET_LINKAGE
 void