🐛 The browser just appears white (#274)

The Okta login page is not rendered when OKTA_BROWSER_AUTH=true. This
started happening after Okta released 2019.02.0, which introduced
subresource integrity checks on certain JavaScript resources.

This bug appears to be Windows specific. I could not reproduce it on
any macOS Mojave configuration regardless of JDK 1.8 or JDK 11 version
I tried.

The root cause is that JavaFX WebEngine on Java 1.8.0_162 or later on
Windows does not correctly handle all subresource integrity checks and
will refuse to load certain referenced resources like CSS and
JavaScript.

 - Strip subresource integrity directives from DOM before it gets to
 the JavaFX WebView (this is a hack, and an ugly one)

Resolves #272

src/main/java/com/okta/tools/authentication/BrowserAuthentication.java

@@ -2,6 +2,7 @@
 
 import com.okta.tools.OktaAwsCliEnvironment;
 import com.okta.tools.helpers.CookieHelper;
+import com.okta.tools.io.SubresourceIntegrityStrippingHack;
 import com.okta.tools.util.NodeListIterable;
 import com.sun.javafx.webkit.WebConsoleListener;
 import javafx.application.Application;
@@ -61,6 +62,7 @@ public void start(final Stage stage) throws IOException {
         URI uri = URI.create(ENVIRONMENT.oktaAwsAppUrl);
         initializeCookies(uri);
 
+        SubresourceIntegrityStrippingHack.overrideHttpsProtocolHandler(ENVIRONMENT);
         webEngine.getLoadWorker().stateProperty()
                 .addListener((ov, oldState, newState) -> {
                     if (webEngine.getDocument() != null) {
@@ -75,7 +77,7 @@ public void start(final Stage stage) throws IOException {
             });
 
         WebConsoleListener.setDefaultListener((webView, message, lineNumber, sourceId) -> {
-            System.out.println("WebConsoleListener: " + message + "[at " + lineNumber + "]");
+            System.out.println("WebConsoleListener: " + message + "[" + webEngine.getLocation() + ":" + lineNumber + "]");
         });
 
         webEngine.load(uri.toASCIIString());

src/main/java/com/okta/tools/io/LoginPageInterceptingProtocolHandler.java

@@ -0,0 +1,41 @@
+package com.okta.tools.io;
+
+import com.okta.tools.OktaAwsCliEnvironment;
+
+import java.io.IOException;
+import java.net.Proxy;
+import java.net.URI;
+import java.net.URL;
+import java.net.URLConnection;
+import java.util.Arrays;
+import java.util.function.BiFunction;
+import java.util.logging.Logger;
+
+final class LoginPageInterceptingProtocolHandler extends sun.net.www.protocol.https.Handler {
+    private static final Logger LOGGER = Logger.getLogger(LoginPageInterceptingProtocolHandler.class.getName());
+    private final OktaAwsCliEnvironment environment;
+    private final BiFunction<URL, URLConnection, URLConnection> filteringUrlConnectionFactory;
+
+    LoginPageInterceptingProtocolHandler(OktaAwsCliEnvironment environment, BiFunction<URL, URLConnection, URLConnection> filteringUrlConnectionFactory) {
+        this.environment = environment;
+        this.filteringUrlConnectionFactory = filteringUrlConnectionFactory;
+    }
+
+    @Override
+    protected URLConnection openConnection(URL url, Proxy proxy) throws IOException {
+        URLConnection urlConnection = super.openConnection(url, proxy);
+        if (environment.oktaOrg.equals(url.getHost()) &&
+            Arrays.asList(
+                    URI.create(environment.oktaAwsAppUrl).getPath(),
+                    "/login/login.htm",
+                    "/auth/services/devicefingerprint"
+            ).contains(url.getPath())
+        ) {
+            LOGGER.finest(() -> String.format("[%s] Using filtering URLConnection", url));
+            return filteringUrlConnectionFactory.apply(url, urlConnection);
+        } else {
+            LOGGER.finest(() -> String.format("[%s] Using unmodified URLConnection", url));
+            return urlConnection;
+        }
+    }
+}

src/main/java/com/okta/tools/io/SubresourceIntegrityStrippingHack.java

@@ -0,0 +1,31 @@
+package com.okta.tools.io;
+
+import com.okta.tools.OktaAwsCliEnvironment;
+
+import java.io.ByteArrayOutputStream;
+import java.io.PrintWriter;
+import java.net.URL;
+import java.util.logging.Logger;
+
+public class SubresourceIntegrityStrippingHack {
+    private static final Logger LOGGER = Logger.getLogger(SubresourceIntegrityStrippingHack.class.getName());
+
+    private SubresourceIntegrityStrippingHack() {}
+
+    public static void overrideHttpsProtocolHandler(OktaAwsCliEnvironment environment) {
+        try {
+            URL.setURLStreamHandlerFactory(protocol -> "https".equals(protocol) ?
+                    new LoginPageInterceptingProtocolHandler(environment,
+                            SubresourceIntegrityStrippingURLConnection::new) :
+                    null
+            );
+            LOGGER.finest("Successfully registered custom protocol handler");
+        } catch (Exception e) {
+            LOGGER.warning(() -> {
+                ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
+                e.printStackTrace(new PrintWriter(outputStream));
+                return String.format("Unable to register custom protocol handler:%n%s", outputStream.toString());
+            });
+        }
+    }
+}

src/main/java/com/okta/tools/io/SubresourceIntegrityStrippingURLConnection.java

@@ -0,0 +1,83 @@
+package com.okta.tools.io;
+
+import org.jsoup.Jsoup;
+import org.jsoup.nodes.DataNode;
+import org.jsoup.nodes.Document;
+import org.jsoup.nodes.Element;
+import org.jsoup.nodes.Node;
+import org.jsoup.select.Elements;
+
+import java.io.ByteArrayInputStream;
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.OutputStream;
+import java.net.URISyntaxException;
+import java.net.URL;
+import java.net.URLConnection;
+import java.nio.charset.StandardCharsets;
+import java.util.logging.Logger;
+
+/**
+ * <p>
+ * Inspired by a find/replace workaround:
+ * https://stackoverflow.com/questions/52572853/failed-integrity-metadata-check-in-javafx-webview-ignores-systemprop
+ * </p>
+ * <p>
+ *     {@literal @bogeylnj} built the original version of this fix and had this comment:
+ *     <blockquote>
+ *         "javaFX.WebEngine with >1.8.0._162 cannot handle "integrity=" (attribute &lt;link&gt; or &lt;script&gt;) checks on files retrievals properly.
+ *         This custom stream handler will disable the integrity checks by replacing "integrity=" and "integrity =" with a "integrity.disabled" counterpart
+ *         This is very susceptible to breaking if Okta changes the response body again as we are making changes based on the format of the characters in their response"
+ *     </blockquote>
+ * </p>
+ * <p>
+ * The current fix expands on the find/replace solution by using JSoup to do a robust HTML5 parse to find and disable
+ * the integrity assertions within the DOM and JavaScript content. If I was feeling particularly bold, I'd parse the
+ * JavaScript with a JavaScript parser, but I like sleep and people using broken software like timely fixes.
+ * </p>
+ */
+final class SubresourceIntegrityStrippingURLConnection extends URLConnection {
+    private static final Logger LOGGER = Logger.getLogger(SubresourceIntegrityStrippingURLConnection.class.getName());
+    private final URLConnection httpsURLConnection;
+
+    SubresourceIntegrityStrippingURLConnection(URL url, URLConnection httpsURLConnection) {
+        super(url);
+        this.httpsURLConnection = httpsURLConnection;
+    }
+
+    @Override
+    public void connect() throws IOException {
+        httpsURLConnection.connect();
+    }
+
+    @Override
+    public InputStream getInputStream() throws IOException {
+        try {
+            Document document = Jsoup.parse(
+                    httpsURLConnection.getInputStream(),
+                    StandardCharsets.UTF_8.name(),
+                    httpsURLConnection.getURL().toURI().toASCIIString()
+            );
+            LOGGER.finest(document::toString);
+            Elements scriptsAssertingIntegrity = document.select("script:containsData(integrity)");
+            for (Element scriptAssertingIntegrity : scriptsAssertingIntegrity) {
+                String scriptWithSuppressedIntegrity = scriptAssertingIntegrity.data()
+                        .replace("integrity", "integrityDisabled");
+                for (Node dataNode : scriptAssertingIntegrity.dataNodes()) {
+                    dataNode.remove();
+                }
+                scriptAssertingIntegrity.appendChild(new DataNode(scriptWithSuppressedIntegrity));
+            }
+            document.select("script[integrity^=sha]").removeAttr("integrity");
+            LOGGER.finest(document::toString);
+            return new ByteArrayInputStream(document.toString().getBytes(StandardCharsets.UTF_8));
+        } catch (URISyntaxException e) {
+            throw new IOException(e);
+        }
+    }
+
+    @Override
+    public OutputStream getOutputStream() throws IOException {
+        return httpsURLConnection.getOutputStream();
+    }
+}