Add winnet function for obtaining the best default route

2 files changed, 77 insertions, 7 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,