feat: verify webview version and prevent loading blank screen

AnkiDroid/src/main/java/com/ichi2/anki/pages/AnkiPackageImporterFragment.kt

@@ -32,6 +32,8 @@ class AnkiPackageImporterFragment : PageFragment() {
         "import-anki-package$filePath"
     }
 
+    override fun requiresModernWebView() = true
+
     override fun onCreateWebViewClient(savedInstanceState: Bundle?): PageWebViewClient {
         // the back callback is only enabled when import is running and showing progress
         val backCallback =

AnkiDroid/src/main/java/com/ichi2/anki/pages/CsvImporter.kt

@@ -37,6 +37,8 @@ class CsvImporter : PageFragment() {
         "import-csv$filePath"
     }
 
+    override fun requiresModernWebView() = true
+
     override fun onCreateWebViewClient(savedInstanceState: Bundle?): PageWebViewClient {
         // the back callback is only enabled when import is running and showing progress
         val backCallback =

AnkiDroid/src/main/java/com/ichi2/anki/pages/PageFragment.kt

@@ -26,10 +26,12 @@ import androidx.core.net.toUri
 import androidx.fragment.app.Fragment
 import com.google.android.material.appbar.MaterialToolbar
 import com.google.android.material.progressindicator.CircularProgressIndicator
+import com.ichi2.anki.AnkiActivity
 import com.ichi2.anki.R
 import com.ichi2.anki.workarounds.OnWebViewRecreatedListener
 import com.ichi2.anki.workarounds.SafeWebViewLayout
 import com.ichi2.themes.Themes
+import com.ichi2.utils.checkWebviewVersion
 import timber.log.Timber
 
 /**
@@ -64,6 +66,8 @@ abstract class PageFragment(
 
     protected open fun onWebViewCreated() { }
 
+    protected open fun requiresModernWebView(): Boolean = false
+
     /**
      * When the webview calls `BridgeCommand("foo")`, the PageFragment execute `bridgeCommands["foo"]`.
      * By default, only bridge command is allowed, subclasses must redefine it if they expect bridge commands.
@@ -73,6 +77,7 @@ abstract class PageFragment(
     /**
      * Ensures that [pageWebViewClient] can receive `bridgeCommand` requests and execute the command from [bridgeCommands].
      */
+
     private fun setupBridgeCommand(pageWebViewClient: PageWebViewClient) {
         if (bridgeCommands.isEmpty()) {
             return
@@ -100,13 +105,18 @@ abstract class PageFragment(
         view: View,
         savedInstanceState: Bundle?,
     ) {
+        val ankiActivity = requireActivity() as AnkiActivity
+        if (requiresModernWebView() && checkWebviewVersion(ankiActivity)) {
+            Timber.w("${this::class.simpleName} requires modern WebView (Chrome 90+), aborting load")
+            ankiActivity.onBackPressedDispatcher.onBackPressed()
+            return
+        }
         server = AnkiServer(this).also { it.start() }
         webViewLayout = view.findViewById(R.id.webview_layout)
 
         view.findViewById<MaterialToolbar>(R.id.toolbar)?.setNavigationOnClickListener {
             requireActivity().onBackPressedDispatcher.onBackPressed()
         }
-
         setupWebView(savedInstanceState)
     }
 

AnkiDroid/src/main/java/com/ichi2/utils/WebViewUtils.kt

@@ -31,14 +31,14 @@ import com.ichi2.anki.CrashReportService
 import com.ichi2.anki.R
 import timber.log.Timber
 
-internal const val OLDEST_WORKING_WEBVIEW_VERSION_CODE = 418306960L
-internal const val OLDEST_WORKING_WEBVIEW_VERSION = 85
+internal const val OLDEST_WORKING_WEBVIEW_VERSION_CODE = 443000000L
+internal const val OLDEST_WORKING_WEBVIEW_VERSION = 90
 
 /**
  * Shows a dialog if the current WebView version is older than the last supported version.
  */
-fun checkWebviewVersion(activity: AnkiActivity) {
-    val userVisibleCode = getChromeLikeWebViewVersionIfOutdated(activity) ?: return
+fun checkWebviewVersion(activity: AnkiActivity): Boolean {
+    val userVisibleCode = getChromeLikeWebViewVersionIfOutdated(activity) ?: return false
 
     // Provide guidance to the user if the WebView is outdated
     val webviewPackageInfo = getAndroidSystemWebViewPackageInfo(activity.packageManager)
@@ -51,6 +51,7 @@ fun checkWebviewVersion(activity: AnkiActivity) {
         Timber.w("WebView is outdated. %s: %s", webviewPackageInfo?.packageName, webviewPackageInfo?.versionName)
         showOutdatedWebViewDialog(activity, userVisibleCode, R.string.link_webview_update)
     }
+    return true
 }
 
 @MainThread
@@ -93,33 +94,33 @@ fun checkWebViewVersionComponents(
     versionCode: Long,
     userAgent: String?,
 ): Int? {
-    // Checking the version code works for most webview packages
-    if (versionCode >= OLDEST_WORKING_WEBVIEW_VERSION_CODE) {
-        Timber.d(
-            "WebView is up to date. %s: %s(%s)",
-            packageName,
-            webviewVersion,
-            versionCode.toString(),
-        )
-        return null
-    }
-
     // Sometimes the webview version code appears too old, and the package name does as well,
     // but it's a webview that advertises modern capabilities via User-Agent in "Chrome" section
     // Our warning is purely advisory, so, let's let those through if User-Agent looks okay
     userAgent?.let {
         val chromeRegex = """Chrome/(\d+)""".toRegex()
         val matchResult = chromeRegex.find(userAgent)?.groupValues?.get(1)
         matchResult?.toInt()?.let {
-            if (it < OLDEST_WORKING_WEBVIEW_VERSION) {
-                // If we got here, even the User-Agent says it's incompatible, return something
-                // potentially useful to the user as a browser version
+            if (it >= OLDEST_WORKING_WEBVIEW_VERSION) {
+                // If the User-Agent says we are modern, trust it and skip further checks.
+                return null
+            } else {
+                // If the User-Agent is explicitly below the floor, return it immediately.
                 return it
             }
         }
     }
-
-    return null
+    // Checking the version code works for most webview packages
+    if (versionCode >= OLDEST_WORKING_WEBVIEW_VERSION_CODE) {
+        Timber.d(
+            "WebView is up to date. %s: %s(%s)",
+            packageName,
+            webviewVersion,
+            versionCode.toString(),
+        )
+        return null
+    }
+    return webviewVersion.split('.').firstOrNull()?.toIntOrNull()
 }
 
 private fun showOutdatedWebViewDialog(

AnkiDroid/src/test/java/com/ichi2/utils/WebViewUtilsTest.kt

@@ -55,5 +55,27 @@ class WebViewUtilsTest {
             ),
             equalTo(null),
         )
+        assertThat(
+            "Should catch old engine (78) in Huawei package even with valid versionCode",
+            checkWebViewVersionComponents(
+                "com.huawei.webview",
+                "12.1.2.322",
+                450000000L,
+                "Mozilla/5.0 (Linux; Android 10; CDY-AN90 Build/HUAWEICDY-AN90; wv) AppleWebKit/537.36 (KHTML, like Gecko) Version/4.0 Chrome/78.0.3904.108 Mobile Safari/537.36",
+            ),
+            equalTo(78),
+        )
+        // Link: https://www.apkmirror.com/apk/huawei/huawei-webview-2/huawei-webview-15-0-4-326-release/
+        // verified version code is 2113L for 15.0.4.326 by analyzing the manifest
+        assertThat(
+            "Huawei v15 with code 21311 should be allowed if UA indicates modern engine (114)",
+            checkWebViewVersionComponents(
+                "com.huawei.webview",
+                "15.0.4.326",
+                21311L,
+                "Mozilla/5.0 (Linux; Android 12; wv) AppleWebKit/537.36 (KHTML, like Gecko) Version/4.0 Chrome/114.0.5735.196 Mobile Safari/537.36",
+            ),
+            equalTo(null),
+        )
     }
 }