tunnel: reinitialize configuration after PnP flaps driver on <10

On older Windows, PnP will unload the driver and reload it. This makes
multiple tunnels impossible, as we knew. But this also happens when
various adapter settings change, like ICS, which is maybe a bigger
issue. Solve this by reloading the configuration after these flaps.

Reported-by: Harland Coles <harland.coles@energy-x.com>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>

2 files changed, 20 insertions, 4 deletions

diff --git a/tunnel/interfacewatcher.go b/tunnel/interfacewatcher.go
index 1abc021d..4e28a6a2 100644
--- a/tunnel/interfacewatcher.go
+++ b/tunnel/interfacewatcher.go
@@ -11,6 +11,7 @@ import (
 	"sync"
 
 	"golang.org/x/sys/windows"
+	"golang.zx2c4.com/wireguard/windows/driver"
 
 	"golang.zx2c4.com/wireguard/conn"
 	"golang.zx2c4.com/wireguard/windows/conf"
@@ -33,6 +34,7 @@ type interfaceWatcher struct {
 	binder  conn.BindSocketToInterface
 	clamper mtuClamper
 	conf    *conf.Config
+	adapter *driver.Adapter
 	luid    winipcfg.LUID
 
 	setupMutex              sync.Mutex
@@ -144,6 +146,20 @@ func watchInterface() (*interfaceWatcher, error) {
 			return
 		}
 		iw.setup(iface.Family)
+
+		if iw.adapter != nil {
+			if state, err := iw.adapter.AdapterState(); err == nil && state == driver.AdapterStateDown {
+				log.Println("Reinitializing adapter configuration")
+				err = iw.adapter.SetConfiguration(iw.conf.ToDriverConfiguration())
+				if err != nil {
+					log.Println(fmt.Errorf("%v: %w", services.ErrorDeviceSetConfig, err))
+				}
+				err = iw.adapter.SetAdapterState(driver.AdapterStateUp)
+				if err != nil {
+					log.Println(fmt.Errorf("%v: %w", services.ErrorDeviceBringUp, err))
+				}
+			}
+		}
 	})
 	if err != nil {
 		return nil, fmt.Errorf("unable to register interface change callback: %w", err)
@@ -151,11 +167,11 @@ func watchInterface() (*interfaceWatcher, error) {
 	return iw, nil
 }
 
-func (iw *interfaceWatcher) Configure(binder conn.BindSocketToInterface, clamper mtuClamper, conf *conf.Config, luid winipcfg.LUID) {
+func (iw *interfaceWatcher) Configure(binder conn.BindSocketToInterface, clamper mtuClamper, adapter *driver.Adapter, conf *conf.Config, luid winipcfg.LUID) {
 	iw.setupMutex.Lock()
 	defer iw.setupMutex.Unlock()
 
-	iw.binder, iw.clamper, iw.conf, iw.luid = binder, clamper, conf, luid
+	iw.binder, iw.clamper, iw.adapter, iw.conf, iw.luid = binder, clamper, adapter, conf, luid
 	for _, event := range iw.storedEvents {
 		if event.luid == luid {
 			iw.setup(event.family)
diff --git a/tunnel/service.go b/tunnel/service.go
index 9df4fecc..decfb571 100644
--- a/tunnel/service.go
+++ b/tunnel/service.go
@@ -276,7 +276,7 @@ func (service *tunnelService) Execute(args []string, r <-chan svc.ChangeRequest,
 
 		var clamper mtuClamper
 		clamper = nativeTun
-		watcher.Configure(bind.(conn.BindSocketToInterface), clamper, config, luid)
+		watcher.Configure(bind.(conn.BindSocketToInterface), clamper, nil, config, luid)
 
 		log.Println("Listening for UAPI requests")
 		go func() {
@@ -298,7 +298,7 @@ func (service *tunnelService) Execute(args []string, r <-chan svc.ChangeRequest,
 		if err != nil {
 			serviceError = services.ErrorDeviceBringUp
 		}
-		watcher.Configure(nil, nil, config, luid)
+		watcher.Configure(nil, nil, adapter, config, luid)
 	}
 
 	err = runScriptCommand(config.Interface.PostUp, config.Name)