cmd/tailscale,java/com/tailscale/ipn: provide OSVersion and DeviceModel for the backend

Signed-off-by: Elias Naur <mail@eliasnaur.com>

android/src/main/java/com/tailscale/ipn/App.java

@@ -97,7 +97,7 @@ public class App extends Application {
 		return getModelName();
 	}
 
-	private String getModelName() {
+	String getModelName() {
 		String manu = Build.MANUFACTURER;
 		String model = Build.MODEL;
 		// Strip manufacturer from model.
@@ -109,6 +109,10 @@ public class App extends Application {
 		return manu + " " + model;
 	}
 
+	String getOSVersion() {
+		return Build.VERSION.RELEASE;
+	}
+
 	// get user defined nickname from Settings
 	// returns null if not available
 	private String getUserConfiguredDeviceName() {

cmd/tailscale/main.go

@@ -191,6 +191,8 @@ func (a *App) runBackend() error {
 				prefs = p.Clone()
 				if first {
 					prefs.Hostname = a.hostname()
+					prefs.OSVersion = a.osVersion()
+					prefs.DeviceModel = a.modelName()
 					go b.backend.SetPrefs(prefs)
 				}
 				a.setPrefs(prefs)
@@ -315,6 +317,39 @@ func (a *App) hostname() string {
 	return hostname
 }
 
+// osVersion returns android.os.Build.MODEL.
+func (a *App) osVersion() string {
+	var version string
+	err := jni.Do(a.jvm, func(env jni.Env) error {
+		cls := jni.GetObjectClass(env, a.appCtx)
+		m := jni.GetMethodID(env, cls, "getOSVersion", "()Ljava/lang/String;")
+		n, err := jni.CallObjectMethod(env, a.appCtx, m)
+		version = jni.GoString(env, jni.String(n))
+		return err
+	})
+	if err != nil {
+		panic(err)
+	}
+	return version
+}
+
+// modelName return the MANUFACTURER + MODEL from
+// android.os.Build.
+func (a *App) modelName() string {
+	var model string
+	err := jni.Do(a.jvm, func(env jni.Env) error {
+		cls := jni.GetObjectClass(env, a.appCtx)
+		m := jni.GetMethodID(env, cls, "getModelName", "()Ljava/lang/String;")
+		n, err := jni.CallObjectMethod(env, a.appCtx, m)
+		model = jni.GoString(env, jni.String(n))
+		return err
+	})
+	if err != nil {
+		panic(err)
+	}
+	return model
+}
+
 // updateNotification updates the foreground persistent status notification.
 func (a *App) updateNotification(service jni.Object, state ipn.State) error {
 	var msg, title string