chrome/android/java/src/org/chromium/chrome/browser/download/ChromeDownloadDelegate.java

// Copyright 2015 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.chrome.browser.download;

import android.Manifest.permission;
import android.app.Activity;
import android.app.DownloadManager;
import android.content.Context;
import android.content.DialogInterface;
import android.content.Intent;
import android.content.pm.PackageManager;
import android.net.Uri;
import android.os.AsyncTask;
import android.os.Environment;
import android.support.v7.app.AlertDialog;
import android.text.TextUtils;
import android.util.Pair;
import android.view.View;
import android.webkit.MimeTypeMap;
import android.widget.TextView;

import org.chromium.base.Log;
import org.chromium.base.ThreadUtils;
import org.chromium.base.annotations.CalledByNative;
import org.chromium.chrome.R;
import org.chromium.chrome.browser.infobar.InfoBarIdentifier;
import org.chromium.chrome.browser.infobar.SimpleConfirmInfoBarBuilder;
import org.chromium.chrome.browser.tab.EmptyTabObserver;
import org.chromium.chrome.browser.tab.Tab;
import org.chromium.chrome.browser.tabmodel.TabModelSelector;
import org.chromium.content.browser.ContentViewDownloadDelegate;
import org.chromium.content.browser.DownloadController;
import org.chromium.content.browser.DownloadInfo;
import org.chromium.content_public.browser.WebContents;
import org.chromium.ui.base.WindowAndroid;
import org.chromium.ui.base.WindowAndroid.PermissionCallback;
import org.chromium.ui.widget.Toast;

import java.io.File;

/**
 * Chrome implementation of the ContentViewDownloadDelegate interface.
 *
 * Listens to POST and GET download events. GET download requests are passed along to the
 * Android Download Manager. POST downloads are expected to be handled natively and listener
 * is responsible for adding the completed download to the download manager.
 *
 * Prompts the user when a dangerous file is downloaded. Auto-opens PDFs after downloading.
 */
public class ChromeDownloadDelegate implements ContentViewDownloadDelegate {
    private static final String TAG = "Download";

    private class DangerousDownloadListener implements SimpleConfirmInfoBarBuilder.Listener {
        @Override
        public void onInfoBarButtonClicked(boolean confirm) {
            assert mTab != null;
            if (mPendingRequest == null) return;
            if (mPendingRequest.hasDownloadId()) {
                nativeDangerousDownloadValidated(mTab, mPendingRequest.getDownloadId(), confirm);
                if (confirm) {
                    showDownloadStartNotification();
                }
                closeBlankTab();
            } else if (confirm) {
                // User confirmed the download.
                if (mPendingRequest.isGETRequest()) {
                    final DownloadInfo info = mPendingRequest;
                    new AsyncTask<Void, Void, Pair<String, String>>() {
                        @Override
                        protected Pair<String, String> doInBackground(Void... params) {
                            Pair<String, String> result = getDownloadDirectoryNameAndFullPath();
                            String fullDirPath = result.second;
                            return doesFileAlreadyExists(fullDirPath, info.getFileName())
                                    ? result : null;
                        }

                        @Override
                        protected void onPostExecute(Pair<String, String> result) {
                            if (result != null) {
                                // File already exists.
                                String dirName = result.first;
                                String fullDirPath = result.second;
                                launchDownloadInfoBar(info, dirName, fullDirPath);
                            } else {
                                enqueueDownloadManagerRequest(info);
                            }
                        }
                    }.execute();
                } else {
                    DownloadInfo newDownloadInfo = DownloadInfo.Builder.fromDownloadInfo(
                            mPendingRequest).setIsSuccessful(true).build();
                    DownloadManagerService.getDownloadManagerService(mContext).onDownloadCompleted(
                            newDownloadInfo);
                }
            } else {
                // User did not accept the download, discard the file if it is a POST download.
                if (!mPendingRequest.isGETRequest()) {
                    discardFile(mPendingRequest.getFilePath());
                }
            }
            mPendingRequest = null;
        }

        @Override
        public void onInfoBarDismissed() {
            if (mPendingRequest != null) {
                if (mPendingRequest.hasDownloadId()) {
                    assert mTab != null;
                    nativeDangerousDownloadValidated(mTab, mPendingRequest.getDownloadId(), false);
                } else if (!mPendingRequest.isGETRequest()) {
                    // Infobar was dismissed, discard the file if a POST download is pending.
                    discardFile(mPendingRequest.getFilePath());
                }
            }
            // Forget the pending request.
            mPendingRequest = null;
        }
    }

    private final DangerousDownloadListener mDangerousDownloadListener;

    // The application context.
    private final Context mContext;
    private Tab mTab;
    private final TabModelSelector mTabModelSelector;

    // Pending download request for a dangerous file.
    private DownloadInfo mPendingRequest;

    /**
     * Creates ChromeDownloadDelegate.
     * @param context The application context.
     * @param tabModelSelector The TabModelSelector responsible for {@code mTab}.
     * @param tab The corresponding tab instance.
     */
    public ChromeDownloadDelegate(
            Context context, TabModelSelector tabModelSelector, Tab tab) {
        mContext = context;
        mTab = tab;
        mTab.addObserver(new EmptyTabObserver() {
            @Override
            public void onDestroyed(Tab tab) {
                mTab = null;
            }
        });

        mTabModelSelector = tabModelSelector;
        mPendingRequest = null;
        mDangerousDownloadListener = new DangerousDownloadListener();
    }

    /**
     * Request a download from the given url, or if a streaming viewer is available stream the
     * content into the viewer.
     * @param downloadInfo Information about the download.
     */
    @Override
    public void requestHttpGetDownload(DownloadInfo downloadInfo) {
        // If we're dealing with A/V content that's not explicitly marked for download, check if it
        // is streamable.
        if (!DownloadManagerService.isAttachment(downloadInfo.getContentDisposition())) {
            // Query the package manager to see if there's a registered handler that matches.
            Intent intent = new Intent(Intent.ACTION_VIEW);
            intent.setDataAndType(Uri.parse(downloadInfo.getUrl()), downloadInfo.getMimeType());
            intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
            // If the intent is resolved to ourselves, we don't want to attempt to load the url
            // only to try and download it again.
            if (DownloadManagerService.openIntent(mContext, intent, false)) {
                return;
            }
        }
        onDownloadStartNoStream(downloadInfo);
    }

    /**
     * Notify the host application a download should be done, even if there is a
     * streaming viewer available for this type.
     *
     * @param downloadInfo Information about the download.
     */
    protected void onDownloadStartNoStream(final DownloadInfo downloadInfo) {
        final String fileName = downloadInfo.getFileName();
        assert !TextUtils.isEmpty(fileName);
        final String newMimeType =
                remapGenericMimeType(downloadInfo.getMimeType(), downloadInfo.getUrl(), fileName);
        new AsyncTask<Void, Void, Object[]>() {
            @Override
            protected Object[] doInBackground(Void... params) {
                // Check to see if we have an SDCard.
                String status = Environment.getExternalStorageState();
                Pair<String, String> result = getDownloadDirectoryNameAndFullPath();
                String dirName = result.first;
                String fullDirPath = result.second;
                boolean fileExists = doesFileAlreadyExists(fullDirPath, fileName);

                return new Object[] {status, dirName, fullDirPath, fileExists};
            }

            @Override
            protected void onPostExecute(Object[] result) {
                String externalStorageState = (String) result[0];
                String dirName = (String) result[1];
                String fullDirPath = (String) result[2];
                Boolean fileExists = (Boolean) result[3];
                if (!checkExternalStorageAndNotify(
                        fileName, fullDirPath, externalStorageState)) {
                    return;
                }
                String url = sanitizeDownloadUrl(downloadInfo);
                if (url == null) return;
                DownloadInfo newInfo = DownloadInfo.Builder.fromDownloadInfo(downloadInfo)
                                               .setUrl(url)
                                               .setMimeType(newMimeType)
                                               .setDescription(url)
                                               .setFileName(fileName)
                                               .setIsGETRequest(true)
                                               .build();

                // TODO(acleung): This is a temp fix to disable auto downloading if flash files.
                // We want to avoid downloading flash files when it is linked as an iframe.
                // The proper fix would be to let chrome knows which frame originated the request.
                if ("application/x-shockwave-flash".equals(newInfo.getMimeType())) return;

                if (isDangerousFile(fileName, newMimeType)) {
                    confirmDangerousDownload(newInfo);
                } else {
                    // Not a dangerous file, proceed.
                    if (fileExists) {
                        launchDownloadInfoBar(newInfo, dirName, fullDirPath);
                    } else {
                        enqueueDownloadManagerRequest(newInfo);
                    }
                }
            }
        }.execute();
    }

    /**
     * Sanitize the URL for the download item.
     *
     * @param downloadInfo Information about the download.
     */
    protected String sanitizeDownloadUrl(DownloadInfo downloadInfo) {
        return downloadInfo.getUrl();
    }

    /**
     * Request user confirmation on a dangerous download.
     *
     * @param downloadInfo Information about the download.
     */
    private void confirmDangerousDownload(DownloadInfo downloadInfo) {
        // A Dangerous file is already pending user confirmation, ignore the new download.
        if (mPendingRequest != null) return;
        // Tab is already destroyed, no need to add an infobar.
        if (mTab == null) return;

        mPendingRequest = downloadInfo;

        int drawableId = R.drawable.infobar_warning;
        final String titleText = nativeGetDownloadWarningText(mPendingRequest.getFileName());
        final String okButtonText = mContext.getResources().getString(R.string.ok);
        final String cancelButtonText = mContext.getResources().getString(R.string.cancel);
        SimpleConfirmInfoBarBuilder.create(mTab, mDangerousDownloadListener,
                InfoBarIdentifier.CONFIRM_DANGEROUS_DOWNLOAD, drawableId, titleText, okButtonText,
                cancelButtonText, true);
    }

    /**
     * Called when a danagerous download is about to start.
     *
     * @param filename File name of the download item.
     * @param downloadId ID of the download.
     */
    @Override
    public void onDangerousDownload(String filename, int downloadId) {
        DownloadInfo downloadInfo = new DownloadInfo.Builder()
                .setFileName(filename)
                .setDescription(filename)
                .setHasDownloadId(true)
                .setDownloadId(downloadId).build();
        confirmDangerousDownload(downloadInfo);
    }

    @Override
    public void requestFileAccess(final long callbackId) {
        if (mTab == null) {
            // TODO(tedchoc): Show toast (only when activity is alive).
            DownloadController.getInstance().onRequestFileAccessResult(callbackId, false);
            return;
        }
        final String storagePermission = android.Manifest.permission.WRITE_EXTERNAL_STORAGE;
        final Activity activity = mTab.getWindowAndroid().getActivity().get();

        if (activity == null) {
            DownloadController.getInstance().onRequestFileAccessResult(callbackId, false);
        } else if (mTab.getWindowAndroid().canRequestPermission(storagePermission)) {
            View view = activity.getLayoutInflater().inflate(
                    R.layout.update_permissions_dialog, null);
            TextView dialogText = (TextView) view.findViewById(R.id.text);
            dialogText.setText(R.string.missing_storage_permission_download_education_text);

            final PermissionCallback permissionCallback = new PermissionCallback() {
                @Override
                public void onRequestPermissionsResult(String[] permissions, int[] grantResults) {
                    DownloadController.getInstance().onRequestFileAccessResult(callbackId,
                            grantResults.length > 0
                                    && grantResults[0] == PackageManager.PERMISSION_GRANTED);
                }
            };

            AlertDialog.Builder builder =
                    new AlertDialog.Builder(activity, R.style.AlertDialogTheme)
                    .setView(view)
                    .setPositiveButton(R.string.infobar_update_permissions_button_text,
                            new DialogInterface.OnClickListener() {
                                @Override
                                public void onClick(DialogInterface dialog, int id) {
                                    if (mTab == null) {
                                        dialog.cancel();
                                        return;
                                    }
                                    mTab.getWindowAndroid().requestPermissions(
                                            new String[] {storagePermission}, permissionCallback);
                                }
                            })
                     .setOnCancelListener(new DialogInterface.OnCancelListener() {
                             @Override
                             public void onCancel(DialogInterface dialog) {
                                 DownloadController.getInstance().onRequestFileAccessResult(
                                         callbackId, false);
                             }
                     });
            builder.create().show();
        } else if (!mTab.getWindowAndroid().isPermissionRevokedByPolicy(storagePermission)) {
            nativeLaunchPermissionUpdateInfoBar(mTab, storagePermission, callbackId);
        } else {
            // TODO(tedchoc): Show toast.
            DownloadController.getInstance().onRequestFileAccessResult(callbackId, false);
        }
    }

    /**
     * Return a pair of directory name and its full path. Note that we create the directory if
     * it does not already exist.
     *
     * @return A pair of directory name and its full path. A pair of <null, null> will be returned
     * in case of an error.
     */
    private static Pair<String, String> getDownloadDirectoryNameAndFullPath() {
        assert !ThreadUtils.runningOnUiThread();
        File dir = Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DOWNLOADS);
        if (!dir.mkdir() && !dir.isDirectory()) return new Pair<>(null, null);
        String dirName = dir.getName();
        String fullDirPath = dir.getPath();
        return new Pair<>(dirName, fullDirPath);
    }

    private static boolean doesFileAlreadyExists(String dirPath, final String fileName) {
        assert !ThreadUtils.runningOnUiThread();
        final File file = new File(dirPath, fileName);
        return file != null && file.exists();
    }

    private static void deleteFileForOverwrite(DownloadInfo info) {
        assert !ThreadUtils.runningOnUiThread();
        File dir = Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DOWNLOADS);
        if (!dir.isDirectory()) return;
        final File file = new File(dir, info.getFileName());
        if (!file.delete()) {
            Log.e(TAG, "Failed to delete a file: " + info.getFileName());
        }
    }

    /**
     * Enqueue download manager request, only from native side. Note that at this point
     * we don't need to show an infobar even when the file already exists.
     *
     * @param overwrite Whether or not we will overwrite the file.
     * @param downloadInfo The download info.
     * @return true iff this request resulted in the tab creating the download to close.
     */
    @CalledByNative
    private boolean enqueueDownloadManagerRequestFromNative(
            final boolean overwrite, final DownloadInfo downloadInfo) {
        if (overwrite) {
            // Android DownloadManager does not have an overwriting option.
            // We remove the file here instead.
            new AsyncTask<Void, Void, Void>() {
                @Override
                public Void doInBackground(Void... params) {
                    deleteFileForOverwrite(downloadInfo);
                    return null;
                }

                @Override
                public void onPostExecute(Void args) {
                    enqueueDownloadManagerRequest(downloadInfo);
                }
            }.execute();
        } else {
            enqueueDownloadManagerRequest(downloadInfo);
        }
        return closeBlankTab();
    }

    private void launchDownloadInfoBar(DownloadInfo info, String dirName, String fullDirPath) {
        if (mTab == null) return;
        nativeLaunchDownloadOverwriteInfoBar(
                ChromeDownloadDelegate.this, mTab, info, info.getFileName(), dirName, fullDirPath);
    }

    /**
     * Enqueue a request to download a file using Android DownloadManager.
     *
     * @param info Download information about the download.
     */
    private void enqueueDownloadManagerRequest(final DownloadInfo info) {
        DownloadManagerService.getDownloadManagerService(
                mContext.getApplicationContext()).enqueueDownloadManagerRequest(info, true);
        closeBlankTab();
    }

    /**
     * Check the external storage and notify user on error.
     *
     * @param fullDirPath The dir path to download a file. Normally this is external storage.
     * @param externalStorageStatus The status of the external storage.
     * @return Whether external storage is ok for downloading.
     */
    private boolean checkExternalStorageAndNotify(
            String filename, String fullDirPath, String externalStorageStatus) {
        if (fullDirPath == null) {
            Log.e(TAG, "Download failed: no SD card");
            alertDownloadFailure(
                    filename, DownloadManager.ERROR_DEVICE_NOT_FOUND);
            return false;
        }
        if (!externalStorageStatus.equals(Environment.MEDIA_MOUNTED)) {
            int reason = DownloadManager.ERROR_DEVICE_NOT_FOUND;
            // Check to see if the SDCard is busy, same as the music app
            if (externalStorageStatus.equals(Environment.MEDIA_SHARED)) {
                Log.e(TAG, "Download failed: SD card unavailable");
                reason = DownloadManager.ERROR_FILE_ERROR;
            } else {
                Log.e(TAG, "Download failed: no SD card");
            }
            alertDownloadFailure(filename, reason);
            return false;
        }
        return true;
    }

    /**
     * Alerts user of download failure.
     *
     * @param fileName Name of the download file.
     * @param reason Reason of failure defined in {@link DownloadManager}
     */
    private void alertDownloadFailure(String fileName, int reason) {
        DownloadManagerService.getDownloadManagerService(
                mContext.getApplicationContext()).onDownloadFailed(fileName, reason);
    }

    /**
     * Called when download starts.
     *
     * @param filename Name of the file.
     * @param mimeType MIME type of the content.
     */
    @Override
    public void onDownloadStarted(String filename, String mimeType) {
        if (!isDangerousFile(filename, mimeType)) {
            showDownloadStartNotification();
            closeBlankTab();
        }
    }

    /**
     * Shows the download started notification.
     */
    private void showDownloadStartNotification() {
        Toast.makeText(mContext, R.string.download_pending, Toast.LENGTH_SHORT).show();
    }

    /**
     * If the given MIME type is null, or one of the "generic" types (text/plain
     * or application/octet-stream) map it to a type that Android can deal with.
     * If the given type is not generic, return it unchanged.
     *
     * We have to implement this ourselves as
     * MimeTypeMap.remapGenericMimeType() is not public.
     * See http://crbug.com/407829.
     *
     * @param mimeType MIME type provided by the server.
     * @param url URL of the data being loaded.
     * @param filename file name obtained from content disposition header
     * @return The MIME type that should be used for this data.
     */
    private static String remapGenericMimeType(String mimeType, String url, String filename) {
        // If we have one of "generic" MIME types, try to deduce
        // the right MIME type from the file extension (if any):
        if (mimeType == null || mimeType.isEmpty() || "text/plain".equals(mimeType)
                || "application/octet-stream".equals(mimeType)
                || "octet/stream".equals(mimeType)
                || "application/force-download".equals(mimeType)) {

            if (!TextUtils.isEmpty(filename)) {
                url = filename;
            }
            String extension = MimeTypeMap.getFileExtensionFromUrl(url);
            String newMimeType = MimeTypeMap.getSingleton().getMimeTypeFromExtension(extension);
            if (newMimeType != null) {
                mimeType = newMimeType;
            } else if (extension.equals("dm")) {
                mimeType = OMADownloadHandler.OMA_DRM_MESSAGE_MIME;
            } else if (extension.equals("dd")) {
                mimeType = OMADownloadHandler.OMA_DOWNLOAD_DESCRIPTOR_MIME;
            }
        }
        return mimeType;
    }

    /**
     * Check whether a file is dangerous.
     *
     * @param filename Name of the file.
     * @param mimeType MIME type of the content.
     * @return true if the file is dangerous, or false otherwise.
     */
    protected boolean isDangerousFile(String filename, String mimeType) {
        return nativeIsDownloadDangerous(filename) || isDangerousExtension(
                MimeTypeMap.getSingleton().getExtensionFromMimeType(mimeType));
    }

    /**
     * Check whether a file extension is dangerous.
     *
     * @param ext Extension of the file.
     * @return true if the file is dangerous, or false otherwise.
     */
    private static boolean isDangerousExtension(String ext) {
        return "apk".equals(ext);
    }

    /**
     * Discards a downloaded file.
     *
     * @param filepath File to be discarded.
     */
    private static void discardFile(final String filepath) {
        new AsyncTask<Void, Void, Void>() {
            @Override
            public Void doInBackground(Void... params) {
                Log.d(TAG, "Discarding download: " + filepath);
                File file = new File(filepath);
                if (file.exists() && !file.delete()) {
                    Log.e(TAG, "Error discarding file: " + filepath);
                }
                return null;
            }
        }.execute();
    }

    /**
     * Close a blank tab just opened for the download purpose.
     * @return true iff the tab was (already) closed.
     */
    private boolean closeBlankTab() {
        if (mTab == null) {
            // We do not want caller to dismiss infobar.
            return true;
        }
        WebContents contents = mTab.getWebContents();
        boolean isInitialNavigation = contents == null
                || contents.getNavigationController().isInitialNavigation();
        if (isInitialNavigation) {
            // Tab is created just for download, close it.
            return mTabModelSelector.closeTab(mTab);
        }
        return false;
    }

    /**
     * For certain download types(OMA for example), android DownloadManager should
     * handle them. Call this function to intercept those downloads.
     *
     * @param url URL to be downloaded.
     * @return whether the DownloadManager should intercept the download.
     */
    public boolean shouldInterceptContextMenuDownload(String url) {
        Uri uri = Uri.parse(url);
        String scheme = uri.normalizeScheme().getScheme();
        if (!"http".equals(scheme) && !"https".equals(scheme)) return false;
        String path = uri.getPath();
        // OMA downloads have extension "dm" or "dd". For the latter, it
        // can be handled when native download completes.
        if (path != null && (path.endsWith(".dm"))) {
            final DownloadInfo downloadInfo = new DownloadInfo.Builder().setUrl(url).build();
            if (mTab == null) return true;
            WindowAndroid window = mTab.getWindowAndroid();
            if (window.hasPermission(permission.WRITE_EXTERNAL_STORAGE)) {
                onDownloadStartNoStream(downloadInfo);
            } else if (window.canRequestPermission(permission.WRITE_EXTERNAL_STORAGE)) {
                PermissionCallback permissionCallback = new PermissionCallback() {
                    @Override
                    public void onRequestPermissionsResult(
                            String[] permissions, int[] grantResults) {
                        if (grantResults.length > 0
                                && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
                            onDownloadStartNoStream(downloadInfo);
                        }
                    }
                };
                window.requestPermissions(
                        new String[] {permission.WRITE_EXTERNAL_STORAGE}, permissionCallback);
            }
            return true;
        }
        return false;
    }

    protected Context getContext() {
        return mContext;
    }

    private static native String nativeGetDownloadWarningText(String filename);
    private static native boolean nativeIsDownloadDangerous(String filename);
    private static native void nativeDangerousDownloadValidated(
            Object tab, int downloadId, boolean accept);
    private static native void nativeLaunchDownloadOverwriteInfoBar(ChromeDownloadDelegate delegate,
            Tab tab, DownloadInfo downloadInfo, String fileName, String dirName,
            String dirFullPath);
    private static native void nativeLaunchPermissionUpdateInfoBar(
            Tab tab, String permission, long callbackId);
}