[WebLayer] Enforce matching version between client and impl

This checks the version of the client and impl code, and throws an
exception if they are not the same.

Change-Id: I64b0d3a47a88d8490ac5fb1c174ad6fe4d9204a8
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1829915Reviewed-by: John Abd-El-Malek <jam@chromium.org>
Commit-Queue: Clark DuVall <cduvall@chromium.org>
Cr-Commit-Position: refs/heads/master@{#702520}

weblayer/browser/java/BUILD.gn

@@ -46,6 +46,7 @@ generate_jni("jni") {
 android_library("client_java") {
   java_files = [
     "org/chromium/weblayer_private/aidl/ObjectWrapper.java",
+    "org/chromium/weblayer_private/aidl/WebLayerVersion.java",
     "org/chromium/weblayer_private/aidl/APICallException.java",
   ]
 

weblayer/browser/java/org/chromium/weblayer_private/WebLayerImpl.java

@@ -22,6 +22,7 @@ import org.chromium.weblayer_private.aidl.IObjectWrapper;
 import org.chromium.weblayer_private.aidl.IProfile;
 import org.chromium.weblayer_private.aidl.IWebLayer;
 import org.chromium.weblayer_private.aidl.ObjectWrapper;
+import org.chromium.weblayer_private.aidl.WebLayerVersion;
 
 @UsedByReflection("WebLayer")
 public final class WebLayerImpl extends IWebLayer.Stub {
@@ -38,6 +39,14 @@ public final class WebLayerImpl extends IWebLayer.Stub {
 
     private WebLayerImpl() {}
 
+    /**
+     * Returns true if the client and implementation versions are compatible.
+     */
+    @UsedByReflection("WebLayer")
+    public static boolean checkVersion(int clientVersion) {
+        return clientVersion == WebLayerVersion.sVersionNumber;
+    }
+
     @Override
     public IProfile createProfile(String path) {
         return new ProfileImpl(path);

weblayer/browser/java/org/chromium/weblayer_private/aidl/WebLayerVersion.java

+// Copyright 2019 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+package org.chromium.weblayer_private.aidl;
+
+/** Holds the current version number of WebLayer. */
+public final class WebLayerVersion { public static int sVersionNumber = 1; }

weblayer/public/java/BUILD.gn

@@ -35,6 +35,7 @@ android_library("java") {
     "org/chromium/weblayer/Profile.java",
     "org/chromium/weblayer/WebLayer.java",
     "org/chromium/weblayer/ChildProcessService.java",
+    "org/chromium/weblayer/UnsupportedVersionException.java",
   ]
 
   deps = [

weblayer/public/java/org/chromium/weblayer/UnsupportedVersionException.java

+// Copyright 2019 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+package org.chromium.weblayer;
+
+/**
+ * Error thrown if client and implementation versions are not compatible.
+ */
+public class UnsupportedVersionException extends Exception {
+    /**
+     * Constructs a new exception with the specified version.
+     */
+    public UnsupportedVersionException(int clientVersion) {
+        super("Unsupported WebLayer version, client version " + clientVersion
+                + " is not supported by the implementation.");
+    }
+}

weblayer/public/java/org/chromium/weblayer/WebLayer.java

@@ -23,6 +23,7 @@ import android.webkit.WebViewFactory;
 import org.chromium.weblayer_private.aidl.APICallException;
 import org.chromium.weblayer_private.aidl.IWebLayer;
 import org.chromium.weblayer_private.aidl.ObjectWrapper;
+import org.chromium.weblayer_private.aidl.WebLayerVersion;
 
 import java.io.File;
 import java.lang.reflect.Constructor;
@@ -45,7 +46,8 @@ public final class WebLayer {
      * Loads the WebLayer implementation and returns the IWebLayer. This does *not* trigger the
      * implementation to start.
      */
-    private static IWebLayer connectToWebLayerImplementation(Application application) {
+    private static IWebLayer connectToWebLayerImplementation(Application application)
+            throws UnsupportedVersionException {
         try {
             // TODO: Make asset loading work on L, where WebViewDelegate doesn't exist.
             // WebViewDelegate.addWebViewAssetPath() accesses the currently loaded package info from
@@ -64,11 +66,19 @@ public final class WebLayer {
             delegate.addWebViewAssetPath(application);
 
             Context remoteContext = createRemoteContext(application);
+            Class webLayerClass = remoteContext.getClassLoader().loadClass(
+                    "org.chromium.weblayer_private.WebLayerImpl");
+
+            // Check version before doing anything else on the implementation side.
+            if (!(boolean) webLayerClass.getMethod("checkVersion", Integer.TYPE)
+                            .invoke(null, WebLayerVersion.sVersionNumber)) {
+                throw new UnsupportedVersionException(WebLayerVersion.sVersionNumber);
+            }
+
             return IWebLayer.Stub.asInterface(
-                    (IBinder) remoteContext.getClassLoader()
-                            .loadClass("org.chromium.weblayer_private.WebLayerImpl")
-                            .getMethod("create")
-                            .invoke(null));
+                    (IBinder) webLayerClass.getMethod("create").invoke(null));
+        } catch (UnsupportedVersionException e) {
+            throw e;
         } catch (Exception e) {
             throw new APICallException(e);
         }
@@ -82,7 +92,8 @@ public final class WebLayer {
      * @return a ListenableFuture whose value will contain the WebLayer once initialization
      * completes
      */
-    public static ListenableFuture<WebLayer> create(Application application) {
+    public static ListenableFuture<WebLayer> create(Application application)
+            throws UnsupportedVersionException {
         if (sFuture == null) {
             IWebLayer iWebLayer = connectToWebLayerImplementation(application);
             sFuture = new WebLayerLoadFuture(iWebLayer, application);