Add winnet function for obtaining the best default route

10 files changed, 236 insertions, 21 deletions

diff --git a/talpid-core/src/tunnel/wireguard/wireguard_go.rs b/talpid-core/src/tunnel/wireguard/wireguard_go.rs
index b4d437f046..e1ded8b3a0 100644
--- a/talpid-core/src/tunnel/wireguard/wireguard_go.rs
+++ b/talpid-core/src/tunnel/wireguard/wireguard_go.rs
@@ -165,7 +165,7 @@ impl WgGoTunnel {
     pub unsafe extern "system" fn default_route_changed_callback(
         event_type: winnet::WinNetDefaultRouteChangeEventType,
         address_family: winnet::WinNetAddrFamily,
-        interface_luid: u64,
+        default_route: winnet::WinNetDefaultRoute,
         _ctx: *mut libc::c_void,
     ) {
         use winapi::shared::{ifdef::NET_LUID, netioapi::ConvertInterfaceLuidToIndex};
@@ -173,7 +173,7 @@ impl WgGoTunnel {
             winnet::WinNetDefaultRouteChangeEventType::DefaultRouteChanged => {
                 let mut iface_idx = 0u32;
                 let iface_luid = NET_LUID {
-                    Value: interface_luid,
+                    Value: default_route.interface_luid,
                 };
                 let status =
                     ConvertInterfaceLuidToIndex(&iface_luid as *const _, &mut iface_idx as *mut _);
diff --git a/talpid-core/src/winnet.rs b/talpid-core/src/winnet.rs
index ab9dff5d06..a648aad982 100644
--- a/talpid-core/src/winnet.rs
+++ b/talpid-core/src/winnet.rs
@@ -5,7 +5,7 @@ use ipnetwork::IpNetwork;
 use libc::{c_void, wchar_t};
 use std::{
     ffi::{OsStr, OsString},
-    net::IpAddr,
+    net::{IpAddr, Ipv4Addr, Ipv6Addr},
     ptr,
 };
 use widestring::WideCString;
@@ -29,6 +29,10 @@ pub enum Error {
     #[error(display = "Failed to obtain GUID for the network interface")]
     GetInterfaceGuid,
 
+    /// Failed to get the current default route.
+    #[error(display = "Failed to obtain default route")]
+    GetDefaultRoute,
+
     /// Failed to read IPv6 status on the TAP network interface.
     #[error(display = "Failed to read IPv6 status on the TAP network interface")]
     GetIpv6Status,
@@ -142,6 +146,12 @@ pub enum WinNetAddrFamily {
     IPV6 = 1,
 }
 
+impl Default for WinNetAddrFamily {
+    fn default() -> Self {
+        WinNetAddrFamily::IPV4
+    }
+}
+
 impl WinNetAddrFamily {
     pub fn to_windows_proto_enum(&self) -> u16 {
         match self {
@@ -152,9 +162,30 @@ impl WinNetAddrFamily {
 }
 
 #[repr(C)]
+#[derive(Default)]
 pub struct WinNetIp {
-    addr_family: WinNetAddrFamily,
-    ip_bytes: [u8; 16],
+    pub addr_family: WinNetAddrFamily,
+    pub ip_bytes: [u8; 16],
+}
+
+#[repr(C)]
+#[derive(Default)]
+pub struct WinNetDefaultRoute {
+    pub interface_luid: u64,
+    pub gateway: WinNetIp,
+}
+
+impl From<WinNetIp> for IpAddr {
+    fn from(addr: WinNetIp) -> IpAddr {
+        match addr.addr_family {
+            WinNetAddrFamily::IPV4 => {
+                let mut bytes: [u8; 4] = Default::default();
+                bytes.clone_from_slice(&addr.ip_bytes[..4]);
+                IpAddr::V4(Ipv4Addr::from(bytes))
+            }
+            WinNetAddrFamily::IPV6 => IpAddr::V6(Ipv6Addr::from(addr.ip_bytes)),
+        }
+    }
 }
 
 impl From<IpAddr> for WinNetIp {
@@ -316,8 +347,8 @@ pub enum WinNetDefaultRouteChangeEventType {
 
 pub type DefaultRouteChangedCallback = unsafe extern "system" fn(
     event_type: WinNetDefaultRouteChangeEventType,
-    addr_family: WinNetAddrFamily,
-    interface_luid: u64,
+    family: WinNetAddrFamily,
+    default_route: WinNetDefaultRoute,
     ctx: *mut c_void,
 );
 
@@ -359,6 +390,26 @@ pub fn deactivate_routing_manager() {
     unsafe { WinNet_DeactivateRouteManager() }
 }
 
+// TODO: Remove attribute once this is in use.
+#[allow(dead_code)]
+pub fn get_best_default_route(
+    family: WinNetAddrFamily,
+) -> Result<Option<WinNetDefaultRoute>, Error> {
+    let mut default_route = WinNetDefaultRoute::default();
+    match unsafe {
+        WinNet_GetBestDefaultRoute(
+            family,
+            &mut default_route as *mut _,
+            Some(log_sink),
+            logging_context(),
+        )
+    } {
+        GetBestDefaultRouteStatus::Success => Ok(Some(default_route)),
+        GetBestDefaultRouteStatus::NotFound => Ok(None),
+        GetBestDefaultRouteStatus::Failure => Err(Error::GetDefaultRoute),
+    }
+}
+
 pub fn add_device_ip_addresses(iface: &String, addresses: &Vec<IpAddr>) -> bool {
     let raw_iface = WideCString::from_str(iface)
         .expect("Failed to convert UTF-8 string to null terminated UCS string")
@@ -379,6 +430,15 @@ mod api {
 
     pub type ConnectivityCallback = unsafe extern "system" fn(is_connected: bool, ctx: *mut c_void);
 
+    #[allow(dead_code)]
+    #[repr(u32)]
+    pub enum FailableOptionalStatus {
+        Success = 0,
+        NotFound = 1,
+        Failure = 2,
+    }
+    pub type GetBestDefaultRouteStatus = FailableOptionalStatus;
+
     extern "system" {
         #[link_name = "WinNet_ActivateRouteManager"]
         pub fn WinNet_ActivateRouteManager(sink: Option<LogSink>, sink_context: *const u8) -> bool;
@@ -415,6 +475,16 @@ mod api {
             sink_context: *const u8,
         ) -> bool;
 
+        // TODO: Remove "allow(dead_code)" this is in use.
+        #[allow(dead_code)]
+        #[link_name = "WinNet_GetBestDefaultRoute"]
+        pub fn WinNet_GetBestDefaultRoute(
+            family: super::WinNetAddrFamily,
+            default_route: *mut super::WinNetDefaultRoute,
+            sink: Option<LogSink>,
+            sink_context: *const u8,
+        ) -> GetBestDefaultRouteStatus;
+
         #[link_name = "WinNet_GetTapInterfaceAlias"]
         pub fn WinNet_GetTapInterfaceAlias(
             tunnel_interface_alias: *mut *mut wchar_t,
diff --git a/windows/winnet/src/winnet/converters.cpp b/windows/winnet/src/winnet/converters.cpp
index 3584f8e34f..dc3f333c6c 100644
--- a/windows/winnet/src/winnet/converters.cpp
+++ b/windows/winnet/src/winnet/converters.cpp
@@ -37,6 +37,33 @@ SOCKADDR_INET IpToNative(const WINNET_IP &from)
 	return to;
 }
 
+WINNET_IP IpFromNative(const SOCKADDR_INET &from)
+{
+	WINNET_IP to = { 0 };
+
+	switch (from.si_family)
+	{
+		case AF_INET:
+		{
+			*reinterpret_cast<uint32_t*>(to.bytes) = static_cast<uint32_t>(from.Ipv4.sin_addr.s_addr);
+			to.family = WINNET_ADDR_FAMILY_IPV4;
+			break;
+		}
+		case AF_INET6:
+		{
+			memcpy(to.bytes, from.Ipv6.sin6_addr.u.Byte, 16);
+			to.family = WINNET_ADDR_FAMILY_IPV6;
+			break;
+		}
+		default:
+		{
+			THROW_ERROR("Invalid network address family");
+		}
+	}
+
+	return to;
+}
+
 } // anonymous namespace
 
 namespace winnet
@@ -115,4 +142,17 @@ std::vector<SOCKADDR_INET> ConvertAddresses(const WINNET_IP *addresses, uint32_t
 	return out;
 }
 
+std::vector<WINNET_IP> ConvertNativeAddresses(const SOCKADDR_INET *addresses, uint32_t numAddresses)
+{
+	std::vector<WINNET_IP> out;
+	out.reserve(numAddresses);
+
+	for (uint32_t i = 0; i < numAddresses; ++i)
+	{
+		out.emplace_back(IpFromNative(addresses[i]));
+	}
+
+	return out;
+}
+
 }
diff --git a/windows/winnet/src/winnet/converters.h b/windows/winnet/src/winnet/converters.h
index 8a1c59e4da..e094728902 100644
--- a/windows/winnet/src/winnet/converters.h
+++ b/windows/winnet/src/winnet/converters.h
@@ -12,5 +12,6 @@ routing::Network ConvertNetwork(const WINNET_IP_NETWORK &in);
 std::optional<routing::Node> ConvertNode(const WINNET_NODE *in);
 std::vector<routing::Route> ConvertRoutes(const WINNET_ROUTE *routes, uint32_t numRoutes);
 std::vector<SOCKADDR_INET> ConvertAddresses(const WINNET_IP *addresses, uint32_t numAddresses);
+std::vector<WINNET_IP> ConvertNativeAddresses(const SOCKADDR_INET *addresses, uint32_t numAddresses);
 
 }
diff --git a/windows/winnet/src/winnet/routing/helpers.cpp b/windows/winnet/src/winnet/routing/helpers.cpp
index 2f171c08a1..9e46b203d4 100644
--- a/windows/winnet/src/winnet/routing/helpers.cpp
+++ b/windows/winnet/src/winnet/routing/helpers.cpp
@@ -6,6 +6,25 @@
 #include <libcommon/error.h>
 #include <libcommon/memory.h>
 
+namespace
+{
+
+bool IsRouteOnPhysicalInterface(const MIB_IPFORWARD_ROW2 &route)
+{
+	switch (route.InterfaceLuid.Info.IfType)
+	{
+		case IF_TYPE_SOFTWARE_LOOPBACK:
+		case IF_TYPE_TUNNEL:
+		case IF_TYPE_PROP_VIRTUAL:
+		{
+			return false;
+		}
+	}
+	return true;
+}
+
+} // anonymous namespace
+
 namespace winnet::routing
 {
 
@@ -124,7 +143,7 @@ bool RouteHasGateway(const MIB_IPFORWARD_ROW2 &route)
 	};
 }
 
-InterfaceAndGateway GetBestDefaultRoute(ADDRESS_FAMILY family)
+std::optional<InterfaceAndGateway> GetBestDefaultRoute(ADDRESS_FAMILY family)
 {
 	PMIB_IPFORWARD_TABLE2 table;
 
@@ -146,7 +165,8 @@ InterfaceAndGateway GetBestDefaultRoute(ADDRESS_FAMILY family)
 	candidates.reserve(table->NumEntries);
 
 	//
-	// Enumerate routes looking for: route 0/0 && gateway specified.
+	// Enumerate routes looking for: route 0/0
+	// The WireGuard interface route has no gateway.
 	//
 
 	for (ULONG i = 0; i < table->NumEntries; ++i)
@@ -154,7 +174,8 @@ InterfaceAndGateway GetBestDefaultRoute(ADDRESS_FAMILY family)
 		const MIB_IPFORWARD_ROW2 &candidate = table->Table[i];
 
 		if (0 == candidate.DestinationPrefix.PrefixLength
-			&& RouteHasGateway(candidate))
+			&& RouteHasGateway(candidate)
+			&& IsRouteOnPhysicalInterface(candidate))
 		{
 			candidates.emplace_back(&candidate);
 		}
@@ -164,7 +185,7 @@ InterfaceAndGateway GetBestDefaultRoute(ADDRESS_FAMILY family)
 
 	if (annotated.empty())
 	{
-		THROW_ERROR("Unable to determine details of default route");
+		return std::nullopt;
 	}
 
 	//
@@ -187,10 +208,10 @@ InterfaceAndGateway GetBestDefaultRoute(ADDRESS_FAMILY family)
 
 	if (false == annotated[0].active)
 	{
-		THROW_ERROR("Unable to identify active default route");
+		return std::nullopt;
 	}
 
-	return InterfaceAndGateway { annotated[0].route->InterfaceLuid, annotated[0].route->NextHop };
+	return std::make_optional(InterfaceAndGateway { annotated[0].route->InterfaceLuid, annotated[0].route->NextHop });
 }
 
 bool AdapterInterfaceEnabled(const IP_ADAPTER_ADDRESSES *adapter, ADDRESS_FAMILY family)
diff --git a/windows/winnet/src/winnet/routing/helpers.h b/windows/winnet/src/winnet/routing/helpers.h
index 37a0acc611..9d73585da9 100644
--- a/windows/winnet/src/winnet/routing/helpers.h
+++ b/windows/winnet/src/winnet/routing/helpers.h
@@ -2,6 +2,7 @@
 
 #include "types.h"
 #include <vector>
+#include <optional>
 
 namespace winnet::routing
 {
@@ -29,7 +30,7 @@ std::vector<AnnotatedRoute> AnnotateRoutes(const std::vector<const MIB_IPFORWARD
 
 bool RouteHasGateway(const MIB_IPFORWARD_ROW2 &route);
 
-InterfaceAndGateway GetBestDefaultRoute(ADDRESS_FAMILY family);
+std::optional<InterfaceAndGateway> GetBestDefaultRoute(ADDRESS_FAMILY family);
 
 bool AdapterInterfaceEnabled(const IP_ADAPTER_ADDRESSES *adapter, ADDRESS_FAMILY family);
 
diff --git a/windows/winnet/src/winnet/routing/routemanager.cpp b/windows/winnet/src/winnet/routing/routemanager.cpp
index 9d5b36ff98..dc38466440 100644
--- a/windows/winnet/src/winnet/routing/routemanager.cpp
+++ b/windows/winnet/src/winnet/routing/routemanager.cpp
@@ -125,7 +125,12 @@ InterfaceAndGateway ResolveNode(ADDRESS_FAMILY family, const std::optional<Node>
 
 	if (false == optionalNode.has_value())
 	{
-		return GetBestDefaultRoute(family);
+		const auto default_route = GetBestDefaultRoute(family);
+		if (!default_route.has_value())
+		{
+			THROW_ERROR("Unable to determine details of default route");
+		}
+		return default_route.value();
 	}
 
 	const auto &node = optionalNode.value();
diff --git a/windows/winnet/src/winnet/winnet.cpp b/windows/winnet/src/winnet/winnet.cpp
index c52fc57d60..4532e43d14 100644
--- a/windows/winnet/src/winnet/winnet.cpp
+++ b/windows/winnet/src/winnet/winnet.cpp
@@ -94,6 +94,55 @@ WinNet_EnableIpv6ForAdapter(
 

 extern "C"

 WINNET_LINKAGE

+WINNET_GBDR_STATUS

+WINNET_API

+WinNet_GetBestDefaultRoute(

+	WINNET_ADDR_FAMILY family,

+	WINNET_DEFAULT_ROUTE *route,

+	MullvadLogSink logSink,

+	void *logSinkContext

+)

+{

+	try

+	{

+		if (nullptr == route)

+		{

+			THROW_ERROR("Invalid argument: route");

+		}

+

+		static const std::pair<WINNET_ADDR_FAMILY, ADDRESS_FAMILY> familyMap[] =

+		{

+			{ WINNET_ADDR_FAMILY_IPV4, static_cast<ADDRESS_FAMILY>(AF_INET) },

+			{ WINNET_ADDR_FAMILY_IPV6, static_cast<ADDRESS_FAMILY>(AF_INET6) }

+		};

+		const auto win_family = common::ValueMapper::Map<>(family, familyMap);

+

+		const auto ifaceAndGateway = GetBestDefaultRoute(win_family);

+

+		if (!ifaceAndGateway.has_value())

+		{

+			return WINNET_GBDR_STATUS_NOT_FOUND;

+		}

+

+		route->interfaceLuid = ifaceAndGateway->iface.Value;

+		const auto ips = winnet::ConvertNativeAddresses(&ifaceAndGateway->gateway, 1);

+		route->gateway = ips[0];

+

+		return WINNET_GBDR_STATUS_SUCCESS;

+	}

+	catch (const std::exception & err)

+	{

+		shared::logging::UnwindAndLog(logSink, logSinkContext, err);

+		return WINNET_GBDR_STATUS_FAILURE;

+	}

+	catch (...)

+	{

+		return WINNET_GBDR_STATUS_FAILURE;

+	}

+}

+

+extern "C"

+WINNET_LINKAGE

 bool

 WINNET_API

 WinNet_GetTapInterfaceAlias(

@@ -480,22 +529,24 @@ WinNet_RegisterDefaultRouteChangedCallback(
 

 			const auto translatedFamily = common::ValueMapper::Map<>(family, familyMap);

 

+			WINNET_DEFAULT_ROUTE defaultRoute = { 0 };

+

 			//

-			// Determine which LUID to forward.

+			// Determine which LUID and gateway to forward.

 			//

 

-			uint64_t translatedLuid = 0;

-

 			if (RouteManager::DefaultRouteChangedEventType::Updated == eventType)

 			{

-				translatedLuid = route.value().iface.Value;

+				const auto ips = winnet::ConvertNativeAddresses(&route.value().gateway, 1);

+				defaultRoute.gateway = ips[0];

+				defaultRoute.interfaceLuid = route.value().iface.Value;

 			}

 

 			//

 			// Forward to client.

 			//

 

-			callback(translatedEventType, translatedFamily, translatedLuid, context);

+			callback(translatedEventType, translatedFamily, defaultRoute, context);

 		};

 

 		*registrationHandle = g_RouteManager->registerDefaultRouteChangedCallback(forwarder);

diff --git a/windows/winnet/src/winnet/winnet.def b/windows/winnet/src/winnet/winnet.def
index 5a1bbfe99f..187ce253d9 100644
--- a/windows/winnet/src/winnet/winnet.def
+++ b/windows/winnet/src/winnet/winnet.def
@@ -10,3 +10,4 @@ EXPORTS
 	WinNet_ActivateRouteManager
 	WinNet_DeactivateRouteManager
 	WinNet_AddDeviceIpAddresses
+	WinNet_GetBestDefaultRoute
diff --git a/windows/winnet/src/winnet/winnet.h b/windows/winnet/src/winnet/winnet.h
index 3597b01a26..c102ebdba3 100644
--- a/windows/winnet/src/winnet/winnet.h
+++ b/windows/winnet/src/winnet/winnet.h
@@ -180,6 +180,31 @@ WINNET_API
 WinNet_DeleteAppliedRoutes(
 );
 
+typedef struct tag_WINNET_DEFAULT_ROUTE
+{
+	uint64_t interfaceLuid;
+	WINNET_IP gateway;
+}
+WINNET_DEFAULT_ROUTE;
+
+enum WINNET_GBDR_STATUS
+{
+	WINNET_GBDR_STATUS_SUCCESS = 0,
+	WINNET_GBDR_STATUS_NOT_FOUND = 1,
+	WINNET_GBDR_STATUS_FAILURE = 2,
+};
+
+extern "C"
+WINNET_LINKAGE
+WINNET_GBDR_STATUS
+WINNET_API
+WinNet_GetBestDefaultRoute(
+	WINNET_ADDR_FAMILY family,
+	WINNET_DEFAULT_ROUTE *route,
+	MullvadLogSink logSink,
+	void *logSinkContext
+);
+
 enum WINNET_DEFAULT_ROUTE_CHANGED_EVENT_TYPE
 {
 	// Best default route changed.
@@ -197,7 +222,7 @@ typedef void (WINNET_API *WinNetDefaultRouteChangedCallback)
 	WINNET_ADDR_FAMILY family,
 
 	// For update events, indicates the interface associated with the new best default route.
-	uint64_t interfaceLuid,
+	WINNET_DEFAULT_ROUTE route,
 
 	void *context
 );