Use Android ID as XUDP basekey

Since Xray 1.8.1, XUDP pass basekey as the global ID. It can maintain the same UDP port on the proxy server outbound.
To enable maximum UDP connectivity, client should pass the device unique ID in the environment variable.

V2rayNG/app/src/main/kotlin/com/v2ray/ang/util/Utils.kt

@@ -13,6 +13,7 @@ import android.content.res.Configuration.UI_MODE_NIGHT_NO
 import android.net.Uri
 import android.os.Build
 import android.os.LocaleList
+import android.provider.Settings
 import android.util.Log
 import android.util.Patterns
 import android.webkit.URLUtil
@@ -317,6 +318,11 @@ object Utils {
         return extDir.absolutePath
     }
 
+    fun getDeviceIdForXUDPBaseKey(): String {
+        val androidId = Settings.Secure.ANDROID_ID.toByteArray(charset("UTF-8"))
+        return Base64.encodeToString(androidId.copyOf(32), Base64.NO_PADDING.or(Base64.URL_SAFE))
+    }
+
     fun getUrlContext(url: String, timeout: Int): String {
         var result: String
         var conn: HttpURLConnection? = null