app/src/main/java/com/stoutner/privacybrowser/dialogs/SslCertificateErrorDialog.java

   1 /*
   2  * Copyright © 2016-2019 Soren Stoutner <soren@stoutner.com>.
   3  *
   4  * This file is part of Privacy Browser <https://www.stoutner.com/privacy-browser>.
   5  *
   6  * Privacy Browser is free software: you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License as published by
   8  * the Free Software Foundation, either version 3 of the License, or
   9  * (at your option) any later version.
  10  *
  11  * Privacy Browser is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  * GNU General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * along with Privacy Browser.  If not, see <http://www.gnu.org/licenses/>.
  18  */
  19
  20 package com.stoutner.privacybrowser.dialogs;
  21
  22 import android.annotation.SuppressLint;
  23 import android.app.Activity;
  24 import android.app.AlertDialog;
  25 import android.app.Dialog;
  26 import android.content.DialogInterface;
  27 import android.content.SharedPreferences;
  28 import android.net.Uri;
  29 import android.net.http.SslCertificate;
  30 import android.net.http.SslError;
  31 import android.os.AsyncTask;
  32 import android.os.Bundle;
  33 import android.preference.PreferenceManager;
  34 import android.text.SpannableStringBuilder;
  35 import android.text.Spanned;
  36 import android.text.style.ForegroundColorSpan;
  37 import android.view.LayoutInflater;
  38 import android.view.View;
  39 import android.view.WindowManager;
  40 import android.webkit.SslErrorHandler;
  41 import android.widget.TextView;
  42
  43 import androidx.annotation.NonNull;
  44 import androidx.fragment.app.DialogFragment;  // The AndroidX dialog fragment must be used or an error is produced on API <=22.
  45
  46 import com.stoutner.privacybrowser.R;
  47 import com.stoutner.privacybrowser.activities.MainWebViewActivity;
  48 import com.stoutner.privacybrowser.fragments.WebViewTabFragment;
  49 import com.stoutner.privacybrowser.views.NestedScrollWebView;
  50
  51 import java.lang.ref.WeakReference;
  52 import java.net.InetAddress;
  53 import java.net.UnknownHostException;
  54 import java.text.DateFormat;
  55 import java.util.Date;
  56
  57 public class SslCertificateErrorDialog extends DialogFragment {
  58     public static SslCertificateErrorDialog displayDialog(SslError error, long webViewFragmentId) {
  59         // Get the various components of the SSL error message.
  60         int primaryErrorIntForBundle = error.getPrimaryError();
  61         String urlWithErrorForBundle = error.getUrl();
  62         SslCertificate sslCertificate = error.getCertificate();
  63         String issuedToCNameForBundle = sslCertificate.getIssuedTo().getCName();
  64         String issuedToONameForBundle = sslCertificate.getIssuedTo().getOName();
  65         String issuedToUNameForBundle = sslCertificate.getIssuedTo().getUName();
  66         String issuedByCNameForBundle = sslCertificate.getIssuedBy().getCName();
  67         String issuedByONameForBundle = sslCertificate.getIssuedBy().getOName();
  68         String issuedByUNameForBundle = sslCertificate.getIssuedBy().getUName();
  69         Date startDateForBundle = sslCertificate.getValidNotBeforeDate();
  70         Date endDateForBundle = sslCertificate.getValidNotAfterDate();
  71
  72         // Create an arguments bundle.
  73         Bundle argumentsBundle = new Bundle();
  74
  75         // Store the SSL error message components in a `Bundle`.
  76         argumentsBundle.putInt("primary_error_int", primaryErrorIntForBundle);
  77         argumentsBundle.putString("url_with_error", urlWithErrorForBundle);
  78         argumentsBundle.putString("issued_to_cname", issuedToCNameForBundle);
  79         argumentsBundle.putString("issued_to_oname", issuedToONameForBundle);
  80         argumentsBundle.putString("issued_to_uname", issuedToUNameForBundle);
  81         argumentsBundle.putString("issued_by_cname", issuedByCNameForBundle);
  82         argumentsBundle.putString("issued_by_oname", issuedByONameForBundle);
  83         argumentsBundle.putString("issued_by_uname", issuedByUNameForBundle);
  84         argumentsBundle.putString("start_date", DateFormat.getDateTimeInstance(DateFormat.MEDIUM, DateFormat.LONG).format(startDateForBundle));
  85         argumentsBundle.putString("end_date", DateFormat.getDateTimeInstance(DateFormat.MEDIUM, DateFormat.LONG).format(endDateForBundle));
  86         argumentsBundle.putLong("webview_fragment_id", webViewFragmentId);
  87
  88         // Create a new instance of the SSL certificate error dialog.
  89         SslCertificateErrorDialog thisSslCertificateErrorDialog = new SslCertificateErrorDialog();
  90
  91         // Add the arguments bundle to the new dialog.
  92         thisSslCertificateErrorDialog.setArguments(argumentsBundle);
  93
  94         // Return the new dialog.
  95         return thisSslCertificateErrorDialog;
  96     }
  97
  98     // `@SuppressLing("InflateParams")` removes the warning about using `null` as the parent view group when inflating the `AlertDialog`.
  99     @SuppressLint("InflateParams")
 100     @Override
 101     @NonNull
 102     public Dialog onCreateDialog(Bundle savedInstanceState) {
 103         // Get a handle for the arguments.
 104         Bundle arguments = getArguments();
 105
 106         // Remove the incorrect lint warning that the arguments might be null.
 107         assert arguments != null;
 108
 109         // Get the variables from the bundle.
 110         int primaryErrorInt = arguments.getInt("primary_error_int");
 111         String urlWithErrors = arguments.getString("url_with_error");
 112         String issuedToCName = arguments.getString("issued_to_cname");
 113         String issuedToOName = arguments.getString("issued_to_oname");
 114         String issuedToUName = arguments.getString("issued_to_uname");
 115         String issuedByCName = arguments.getString("issued_by_cname");
 116         String issuedByOName = arguments.getString("issued_by_oname");
 117         String issuedByUName = arguments.getString("issued_by_uname");
 118         String startDate = arguments.getString("start_date");
 119         String endDate = arguments.getString("end_date");
 120         long webViewFragmentId = arguments.getLong("webview_fragment_id");
 121
 122         // Get the current position of this WebView fragment.
 123         int webViewPosition = MainWebViewActivity.webViewPagerAdapter.getPositionForId(webViewFragmentId);
 124
 125         // Get the WebView tab fragment.
 126         WebViewTabFragment webViewTabFragment = MainWebViewActivity.webViewPagerAdapter.getPageFragment(webViewPosition);
 127
 128         // Get the fragment view.
 129         View fragmentView = webViewTabFragment.getView();
 130
 131         // Remove the incorrect lint warning below that the fragment view might be null.
 132         assert fragmentView != null;
 133
 134         // Get a handle for the current WebView.
 135         NestedScrollWebView nestedScrollWebView = fragmentView.findViewById(R.id.nestedscroll_webview);
 136
 137         // Get a handle for the SSL error handler.
 138         SslErrorHandler sslErrorHandler = nestedScrollWebView.getSslErrorHandler();
 139
 140         // Remove the incorrect lint warning that `getActivity()` might be null.
 141         assert getActivity() != null;
 142
 143         // Get the activity's layout inflater.
 144         LayoutInflater layoutInflater = getActivity().getLayoutInflater();
 145
 146         // Use an alert dialog builder to create the alert dialog.
 147         AlertDialog.Builder dialogBuilder;
 148
 149         // Get a handle for the shared preferences.
 150         SharedPreferences sharedPreferences = PreferenceManager.getDefaultSharedPreferences(getContext());
 151
 152         // Get the screenshot and theme preferences.
 153         boolean darkTheme = sharedPreferences.getBoolean("dark_theme", false);
 154         boolean allowScreenshots = sharedPreferences.getBoolean("allow_screenshots", false);
 155
 156         // Set the style and icon according to the theme.
 157         if (darkTheme) {
 158             // Set the style.
 159             dialogBuilder = new AlertDialog.Builder(getActivity(), R.style.PrivacyBrowserAlertDialogDark);
 160
 161             // Set the icon.
 162             dialogBuilder.setIcon(R.drawable.ssl_certificate_enabled_dark);
 163         } else {
 164             // Set the style.
 165             dialogBuilder = new AlertDialog.Builder(getActivity(), R.style.PrivacyBrowserAlertDialogLight);
 166
 167             // Set the icon.
 168             dialogBuilder.setIcon(R.drawable.ssl_certificate_enabled_light);
 169         }
 170
 171         // Set the title.
 172         dialogBuilder.setTitle(R.string.ssl_certificate_error);
 173
 174         // Set the view.  The parent view is `null` because it will be assigned by `AlertDialog`.
 175         dialogBuilder.setView(layoutInflater.inflate(R.layout.ssl_certificate_error, null));
 176
 177         // Set a listener on the cancel button.
 178         dialogBuilder.setNegativeButton(R.string.cancel, (DialogInterface dialog, int which) -> {
 179             // Check to make sure the SSL error handler is not null.  This might happen if multiple dialogs are displayed at once.
 180             if (sslErrorHandler != null) {
 181                 // Cancel the request.
 182                 sslErrorHandler.cancel();
 183
 184                 // Reset the SSL error handler.
 185                 nestedScrollWebView.resetSslErrorHandler();
 186             }
 187         });
 188
 189         // Set a listener on the proceed button.
 190         dialogBuilder.setPositiveButton(R.string.proceed, (DialogInterface dialog, int which) -> {
 191             // Check to make sure the SSL error handler is not null.  This might happen if multiple dialogs are displayed at once.
 192             if (sslErrorHandler != null) {
 193                 // Cancel the request.
 194                 sslErrorHandler.proceed();
 195
 196                 // Reset the SSL error handler.
 197                 nestedScrollWebView.resetSslErrorHandler();
 198             }
 199         });
 200
 201
 202         // Create an alert dialog from the alert dialog builder.
 203         AlertDialog alertDialog = dialogBuilder.create();
 204
 205         // Disable screenshots if not allowed.
 206         if (!allowScreenshots) {
 207             // Remove the warning below that `getWindow()` might be null.
 208             assert alertDialog.getWindow() != null;
 209
 210             // Disable screenshots.
 211             alertDialog.getWindow().addFlags(WindowManager.LayoutParams.FLAG_SECURE);
 212         }
 213
 214         // Get a URI for the URL with errors.
 215         Uri uriWithErrors = Uri.parse(urlWithErrors);
 216
 217         // Get the IP addresses for the URI.
 218         new GetIpAddresses(getActivity(), alertDialog).execute(uriWithErrors.getHost());
 219
 220         // The alert dialog must be shown before the contents can be modified.
 221         alertDialog.show();
 222
 223         // Get handles for the `TextViews`
 224         TextView primaryErrorTextView = alertDialog.findViewById(R.id.primary_error);
 225         TextView urlTextView = alertDialog.findViewById(R.id.url);
 226         TextView issuedToCNameTextView = alertDialog.findViewById(R.id.issued_to_cname);
 227         TextView issuedToONameTextView = alertDialog.findViewById(R.id.issued_to_oname);
 228         TextView issuedToUNameTextView = alertDialog.findViewById(R.id.issued_to_uname);
 229         TextView issuedByTextView = alertDialog.findViewById(R.id.issued_by_textview);
 230         TextView issuedByCNameTextView = alertDialog.findViewById(R.id.issued_by_cname);
 231         TextView issuedByONameTextView = alertDialog.findViewById(R.id.issued_by_oname);
 232         TextView issuedByUNameTextView = alertDialog.findViewById(R.id.issued_by_uname);
 233         TextView validDatesTextView = alertDialog.findViewById(R.id.valid_dates_textview);
 234         TextView startDateTextView = alertDialog.findViewById(R.id.start_date);
 235         TextView endDateTextView = alertDialog.findViewById(R.id.end_date);
 236
 237         // Setup the common strings.
 238         String urlLabel = getString(R.string.url_label) + "  ";
 239         String cNameLabel = getString(R.string.common_name) + "  ";
 240         String oNameLabel = getString(R.string.organization) + "  ";
 241         String uNameLabel = getString(R.string.organizational_unit) + "  ";
 242         String startDateLabel = getString(R.string.start_date) + "  ";
 243         String endDateLabel = getString(R.string.end_date) + "  ";
 244
 245         // Create a spannable string builder for each text view that needs multiple colors of text.
 246         SpannableStringBuilder urlStringBuilder = new SpannableStringBuilder(urlLabel + urlWithErrors);
 247         SpannableStringBuilder issuedToCNameStringBuilder = new SpannableStringBuilder(cNameLabel + issuedToCName);
 248         SpannableStringBuilder issuedToONameStringBuilder = new SpannableStringBuilder(oNameLabel + issuedToOName);
 249         SpannableStringBuilder issuedToUNameStringBuilder = new SpannableStringBuilder(uNameLabel + issuedToUName);
 250         SpannableStringBuilder issuedByCNameStringBuilder = new SpannableStringBuilder(cNameLabel + issuedByCName);
 251         SpannableStringBuilder issuedByONameStringBuilder = new SpannableStringBuilder(oNameLabel + issuedByOName);
 252         SpannableStringBuilder issuedByUNameStringBuilder = new SpannableStringBuilder(uNameLabel + issuedByUName);
 253         SpannableStringBuilder startDateStringBuilder = new SpannableStringBuilder(startDateLabel + startDate);
 254         SpannableStringBuilder endDateStringBuilder = new SpannableStringBuilder((endDateLabel + endDate));
 255
 256         // Create a red foreground color span.  The deprecated `getResources().getColor` must be used until the minimum API >= 23.
 257         ForegroundColorSpan redColorSpan = new ForegroundColorSpan(getResources().getColor(R.color.red_a700));
 258
 259         // Create a blue `ForegroundColorSpan`.
 260         ForegroundColorSpan blueColorSpan;
 261
 262         // Set a blue color span according to the theme.  The deprecated `getResources().getColor` must be used until the minimum API >= 23.
 263         if (darkTheme) {
 264             blueColorSpan = new ForegroundColorSpan(getResources().getColor(R.color.blue_400));
 265         } else {
 266             blueColorSpan = new ForegroundColorSpan(getResources().getColor(R.color.blue_700));
 267         }
 268
 269         // Setup the spans to display the certificate information in blue.  `SPAN_INCLUSIVE_INCLUSIVE` allows the span to grow in either direction.
 270         urlStringBuilder.setSpan(blueColorSpan, urlLabel.length(), urlStringBuilder.length(), Spanned.SPAN_INCLUSIVE_INCLUSIVE);
 271         issuedToCNameStringBuilder.setSpan(blueColorSpan, cNameLabel.length(), issuedToCNameStringBuilder.length(), Spanned.SPAN_INCLUSIVE_INCLUSIVE);
 272         issuedToONameStringBuilder.setSpan(blueColorSpan, oNameLabel.length(), issuedToONameStringBuilder.length(), Spanned.SPAN_INCLUSIVE_INCLUSIVE);
 273         issuedToUNameStringBuilder.setSpan(blueColorSpan, uNameLabel.length(), issuedToUNameStringBuilder.length(), Spanned.SPAN_INCLUSIVE_INCLUSIVE);
 274         issuedByCNameStringBuilder.setSpan(blueColorSpan, cNameLabel.length(), issuedByCNameStringBuilder.length(), Spanned.SPAN_INCLUSIVE_INCLUSIVE);
 275         issuedByONameStringBuilder.setSpan(blueColorSpan, oNameLabel.length(), issuedByONameStringBuilder.length(), Spanned.SPAN_INCLUSIVE_INCLUSIVE);
 276         issuedByUNameStringBuilder.setSpan(blueColorSpan, uNameLabel.length(), issuedByUNameStringBuilder.length(), Spanned.SPAN_INCLUSIVE_INCLUSIVE);
 277         startDateStringBuilder.setSpan(blueColorSpan, startDateLabel.length(), startDateStringBuilder.length(), Spanned.SPAN_INCLUSIVE_INCLUSIVE);
 278         endDateStringBuilder.setSpan(blueColorSpan, endDateLabel.length(), endDateStringBuilder.length(), Spanned.SPAN_INCLUSIVE_INCLUSIVE);
 279
 280         // Initialize `primaryErrorString`.
 281         String primaryErrorString = "";
 282
 283         // Highlight the primary error in red and store the primary error string in `primaryErrorString`.
 284         switch (primaryErrorInt) {
 285             case SslError.SSL_IDMISMATCH:
 286                 // Change the URL span colors to red.
 287                 urlStringBuilder.setSpan(redColorSpan, urlLabel.length(), urlStringBuilder.length(), Spanned.SPAN_INCLUSIVE_INCLUSIVE);
 288                 issuedToCNameStringBuilder.setSpan(redColorSpan, cNameLabel.length(), issuedToCNameStringBuilder.length(), Spanned.SPAN_INCLUSIVE_INCLUSIVE);
 289
 290                 // Store the primary error string.
 291                 primaryErrorString = getString(R.string.cn_mismatch);
 292                 break;
 293
 294             case SslError.SSL_UNTRUSTED:
 295                 // Change the issued by text view text to red.  The deprecated `getResources().getColor` must be used until the minimum API >= 23.
 296                 issuedByTextView.setTextColor(getResources().getColor(R.color.red_a700));
 297
 298                 // Change the issued by span color to red.
 299                 issuedByCNameStringBuilder.setSpan(redColorSpan, cNameLabel.length(), issuedByCNameStringBuilder.length(), Spanned.SPAN_INCLUSIVE_INCLUSIVE);
 300                 issuedByONameStringBuilder.setSpan(redColorSpan, oNameLabel.length(), issuedByONameStringBuilder.length(), Spanned.SPAN_INCLUSIVE_INCLUSIVE);
 301                 issuedByUNameStringBuilder.setSpan(redColorSpan, uNameLabel.length(), issuedByUNameStringBuilder.length(), Spanned.SPAN_INCLUSIVE_INCLUSIVE);
 302
 303                 // Store the primary error string.
 304                 primaryErrorString = getString(R.string.untrusted);
 305                 break;
 306
 307             case SslError.SSL_DATE_INVALID:
 308                 // Change the valid dates text view text to red.  The deprecated `getResources().getColor` must be used until the minimum API >= 23.
 309                 validDatesTextView.setTextColor(getResources().getColor(R.color.red_a700));
 310
 311                 // Change the date span colors to red.
 312                 startDateStringBuilder.setSpan(redColorSpan, startDateLabel.length(), startDateStringBuilder.length(), Spanned.SPAN_INCLUSIVE_INCLUSIVE);
 313                 endDateStringBuilder.setSpan(redColorSpan, endDateLabel.length(), endDateStringBuilder.length(), Spanned.SPAN_INCLUSIVE_INCLUSIVE);
 314
 315                 // Store the primary error string.
 316                 primaryErrorString = getString(R.string.invalid_date);
 317                 break;
 318
 319             case SslError.SSL_NOTYETVALID:
 320                 // Change the start date span color to red.
 321                 startDateStringBuilder.setSpan(redColorSpan, startDateLabel.length(), startDateStringBuilder.length(), Spanned.SPAN_INCLUSIVE_INCLUSIVE);
 322
 323                 // Store the primary error string.
 324                 primaryErrorString = getString(R.string.future_certificate);
 325                 break;
 326
 327             case SslError.SSL_EXPIRED:
 328                 // Change the end date span color to red.
 329                 endDateStringBuilder.setSpan(redColorSpan, endDateLabel.length(), endDateStringBuilder.length(), Spanned.SPAN_INCLUSIVE_INCLUSIVE);
 330
 331                 // Store the primary error string.
 332                 primaryErrorString = getString(R.string.expired_certificate);
 333                 break;
 334
 335             case SslError.SSL_INVALID:
 336                 // Store the primary error string.
 337                 primaryErrorString = getString(R.string.invalid_certificate);
 338                 break;
 339         }
 340
 341
 342         // Display the strings.
 343         primaryErrorTextView.setText(primaryErrorString);
 344         urlTextView.setText(urlStringBuilder);
 345         issuedToCNameTextView.setText(issuedToCNameStringBuilder);
 346         issuedToONameTextView.setText(issuedToONameStringBuilder);
 347         issuedToUNameTextView.setText(issuedToUNameStringBuilder);
 348         issuedByCNameTextView.setText(issuedByCNameStringBuilder);
 349         issuedByONameTextView.setText(issuedByONameStringBuilder);
 350         issuedByUNameTextView.setText(issuedByUNameStringBuilder);
 351         startDateTextView.setText(startDateStringBuilder);
 352         endDateTextView.setText(endDateStringBuilder);
 353
 354         // `onCreateDialog` requires the return of an alert dialog.
 355         return alertDialog;
 356     }
 357
 358
 359     // This must run asynchronously because it involves a network request.  `String` declares the parameters.  `Void` does not declare progress units.  `SpannableStringBuilder` contains the results.
 360     private static class GetIpAddresses extends AsyncTask<String, Void, SpannableStringBuilder> {
 361         // The weak references are used to determine if the activity or the alert dialog have disappeared while the AsyncTask is running.
 362         private WeakReference<Activity> activityWeakReference;
 363         private WeakReference<AlertDialog> alertDialogWeakReference;
 364
 365         GetIpAddresses(Activity activity, AlertDialog alertDialog) {
 366             // Populate the weak references.
 367             activityWeakReference = new WeakReference<>(activity);
 368             alertDialogWeakReference = new WeakReference<>(alertDialog);
 369         }
 370
 371         @Override
 372         protected SpannableStringBuilder doInBackground(String... domainName) {
 373             // Get handles for the activity and the alert dialog.
 374             Activity activity = activityWeakReference.get();
 375             AlertDialog alertDialog = alertDialogWeakReference.get();
 376
 377             // Abort if the activity or the dialog is gone.
 378             if ((activity == null) || (activity.isFinishing()) || (alertDialog == null)) {
 379                 return new SpannableStringBuilder();
 380             }
 381
 382             // Initialize an IP address string builder.
 383             StringBuilder ipAddresses = new StringBuilder();
 384
 385             // Get an array with the IP addresses for the host.
 386             try {
 387                 // Get an array with all the IP addresses for the domain.
 388                 InetAddress[] inetAddressesArray = InetAddress.getAllByName(domainName[0]);
 389
 390                 // Add each IP address to the string builder.
 391                 for (InetAddress inetAddress : inetAddressesArray) {
 392                     if (ipAddresses.length() == 0) {  // This is the first IP address.
 393                         // Add the IP Address to the string builder.
 394                         ipAddresses.append(inetAddress.getHostAddress());
 395                     } else {  // This is not the first IP address.
 396                         // Add a line break to the string builder first.
 397                         ipAddresses.append("\n");
 398
 399                         // Add the IP address to the string builder.
 400                         ipAddresses.append(inetAddress.getHostAddress());
 401                     }
 402                 }
 403             } catch (UnknownHostException exception) {
 404                 // Do nothing.
 405             }
 406
 407             // Set the label.
 408             String ipAddressesLabel = activity.getString(R.string.ip_addresses) + "  ";
 409
 410             // Create a spannable string builder.
 411             SpannableStringBuilder ipAddressesStringBuilder = new SpannableStringBuilder(ipAddressesLabel + ipAddresses);
 412
 413             // Get a handle for the shared preferences.
 414             SharedPreferences sharedPreferences = PreferenceManager.getDefaultSharedPreferences(activity.getApplicationContext());
 415
 416             // Get the screenshot and theme preferences.
 417             boolean darkTheme = sharedPreferences.getBoolean("dark_theme", false);
 418
 419             // Create a blue foreground color span.
 420             ForegroundColorSpan blueColorSpan;
 421
 422             // Set the blue color span according to the theme.  The deprecated `getColor()` must be used until the minimum API >= 23.
 423             if (darkTheme) {
 424                 blueColorSpan = new ForegroundColorSpan(activity.getResources().getColor(R.color.blue_400));
 425             } else {
 426                 blueColorSpan = new ForegroundColorSpan(activity.getResources().getColor(R.color.blue_700));
 427             }
 428
 429             // Set the string builder to display the certificate information in blue.  `SPAN_INCLUSIVE_INCLUSIVE` allows the span to grow in either direction.
 430             ipAddressesStringBuilder.setSpan(blueColorSpan, ipAddressesLabel.length(), ipAddressesStringBuilder.length(), Spanned.SPAN_INCLUSIVE_INCLUSIVE);
 431
 432             // Return the formatted string.
 433             return ipAddressesStringBuilder;
 434         }
 435
 436         // `onPostExecute()` operates on the UI thread.
 437         @Override
 438         protected void onPostExecute(SpannableStringBuilder ipAddresses) {
 439             // Get handles for the activity and the alert dialog.
 440             Activity activity = activityWeakReference.get();
 441             AlertDialog alertDialog = alertDialogWeakReference.get();
 442
 443             // Abort if the activity or the alert dialog is gone.
 444             if ((activity == null) || (activity.isFinishing()) || (alertDialog == null)) {
 445                 return;
 446             }
 447
 448             // Get a handle for the IP addresses text view.
 449             TextView ipAddressesTextView = alertDialog.findViewById(R.id.ip_addresses);
 450
 451             // Populate the IP addresses text view.
 452             ipAddressesTextView.setText(ipAddresses);
 453         }
 454     }
 455 }