Implement a libsignal-net shadowing web socket.

app/src/main/java/org/thoughtcrime/securesms/dependencies/ApplicationDependencyProvider.java

@@ -45,6 +45,7 @@ import org.thoughtcrime.securesms.jobs.TypingSendJob;
 import org.thoughtcrime.securesms.keyvalue.SignalStore;
 import org.thoughtcrime.securesms.megaphone.MegaphoneRepository;
 import org.thoughtcrime.securesms.messages.IncomingMessageObserver;
+import org.thoughtcrime.securesms.net.DefaultWebSocketShadowingBridge;
 import org.thoughtcrime.securesms.net.SignalWebSocketHealthMonitor;
 import org.thoughtcrime.securesms.net.StandardUserAgentInterceptor;
 import org.thoughtcrime.securesms.notifications.MessageNotifier;
@@ -92,9 +93,11 @@ import org.whispersystems.signalservice.api.util.UptimeSleepTimer;
 import org.whispersystems.signalservice.api.websocket.WebSocketFactory;
 import org.whispersystems.signalservice.internal.configuration.SignalServiceConfiguration;
 import org.whispersystems.signalservice.internal.websocket.LibSignalNetwork;
+import org.whispersystems.signalservice.internal.websocket.ShadowingWebSocketConnection;
 import org.whispersystems.signalservice.internal.websocket.WebSocketConnection;
 import org.whispersystems.signalservice.internal.websocket.LibSignalChatConnection;
 import org.whispersystems.signalservice.internal.websocket.OkHttpWebSocketConnection;
+import org.whispersystems.signalservice.internal.websocket.WebSocketShadowingBridge;
 
 import java.util.Optional;
 import java.util.concurrent.TimeUnit;
@@ -294,7 +297,8 @@ public class ApplicationDependencyProvider implements ApplicationDependencies.Pr
   public @NonNull SignalWebSocket provideSignalWebSocket(@NonNull Supplier<SignalServiceConfiguration> signalServiceConfigurationSupplier, @NonNull Supplier<LibSignalNetwork> libSignalNetworkSupplier) {
     SleepTimer                   sleepTimer      = !SignalStore.account().isFcmEnabled() || SignalStore.internalValues().isWebsocketModeForced() ? new AlarmSleepTimer(context) : new UptimeSleepTimer() ;
     SignalWebSocketHealthMonitor healthMonitor   = new SignalWebSocketHealthMonitor(context, sleepTimer);
-    SignalWebSocket              signalWebSocket = new SignalWebSocket(provideWebSocketFactory(signalServiceConfigurationSupplier, healthMonitor, libSignalNetworkSupplier));
+    WebSocketShadowingBridge     bridge          = new DefaultWebSocketShadowingBridge(context);
+    SignalWebSocket              signalWebSocket = new SignalWebSocket(provideWebSocketFactory(signalServiceConfigurationSupplier, healthMonitor, libSignalNetworkSupplier, bridge));
 
     healthMonitor.monitor(signalWebSocket);
 
@@ -401,7 +405,11 @@ public class ApplicationDependencyProvider implements ApplicationDependencies.Pr
     return provideClientZkOperations(signalServiceConfiguration).getReceiptOperations();
   }
 
-  @NonNull WebSocketFactory provideWebSocketFactory(@NonNull Supplier<SignalServiceConfiguration> signalServiceConfigurationSupplier, @NonNull SignalWebSocketHealthMonitor healthMonitor, @NonNull Supplier<LibSignalNetwork> libSignalNetworkSupplier) {
+  @NonNull WebSocketFactory provideWebSocketFactory(@NonNull Supplier<SignalServiceConfiguration> signalServiceConfigurationSupplier,
+                                                    @NonNull SignalWebSocketHealthMonitor healthMonitor,
+                                                    @NonNull Supplier<LibSignalNetwork> libSignalNetworkSupplier,
+                                                    @NonNull WebSocketShadowingBridge bridge)
+  {
     return new WebSocketFactory() {
       @Override
       public WebSocketConnection createWebSocket() {
@@ -415,6 +423,20 @@ public class ApplicationDependencyProvider implements ApplicationDependencies.Pr
 
       @Override
       public WebSocketConnection createUnidentifiedWebSocket() {
+        int shadowPercentage = FeatureFlags.libSignalWebSocketShadowingPercentage();
+        if (shadowPercentage > 0) {
+          return new ShadowingWebSocketConnection(
+              "unauth-shadow",
+              signalServiceConfigurationSupplier.get(),
+              Optional.empty(),
+              BuildConfig.SIGNAL_AGENT,
+              healthMonitor,
+              Stories.isFeatureEnabled(),
+              libSignalNetworkSupplier.get().createChatService(null),
+              shadowPercentage,
+              bridge
+          );
+        }
         if (FeatureFlags.libSignalWebSocketEnabled()) {
           LibSignalNetwork network = libSignalNetworkSupplier.get();
           return new LibSignalChatConnection(

app/src/main/java/org/thoughtcrime/securesms/keyvalue/InternalValues.java

@@ -32,6 +32,7 @@ public final class InternalValues extends SignalStoreValues {
   public static final String LAST_SCROLL_POSITION                 = "internal.last_scroll_position";
   public static final String CONVERSATION_ITEM_V2_MEDIA           = "internal.conversation_item_v2_media";
   public static final String FORCE_ENTER_RESTORE_V2_FLOW          = "internal.force_enter_restore_v2_flow";
+  public static final String WEB_SOCKET_SHADOWING_STATS           = "internal.web_socket_shadowing_stats";
 
   InternalValues(KeyValueStore store) {
     super(store);
@@ -219,4 +220,13 @@ public final class InternalValues extends SignalStoreValues {
   public boolean enterRestoreV2Flow() {
     return FeatureFlags.restoreAfterRegistration() && getBoolean(FORCE_ENTER_RESTORE_V2_FLOW, false);
   }
+
+  public synchronized void setWebSocketShadowingStats(byte[] bytes) {
+    putBlob(WEB_SOCKET_SHADOWING_STATS, bytes);
+  }
+
+  public synchronized byte[] getWebSocketShadowingStats(byte[] defaultValue) {
+    return getBlob(WEB_SOCKET_SHADOWING_STATS, defaultValue);
+  }
+
 }

app/src/main/java/org/thoughtcrime/securesms/net/DefaultWebSocketShadowingBridge.kt

@@ -0,0 +1,59 @@
+/*
+ * Copyright 2024 Signal Messenger, LLC
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+package org.thoughtcrime.securesms.net
+
+import android.app.Application
+import android.app.Notification
+import android.app.PendingIntent
+import android.content.Intent
+import androidx.core.app.NotificationCompat
+import androidx.core.app.NotificationManagerCompat
+import org.signal.core.util.PendingIntentFlags
+import org.thoughtcrime.securesms.R
+import org.thoughtcrime.securesms.keyvalue.InternalValues
+import org.thoughtcrime.securesms.keyvalue.SignalStore
+import org.thoughtcrime.securesms.logsubmit.SubmitDebugLogActivity
+import org.thoughtcrime.securesms.notifications.NotificationChannels
+import org.thoughtcrime.securesms.notifications.NotificationIds
+import org.thoughtcrime.securesms.util.FeatureFlags
+import org.whispersystems.signalservice.internal.websocket.WebSocketShadowingBridge
+
+/**
+ * Implements a [WebSocketShadowingBridge] to provide shadowing-specific functionality to
+ * [org.whispersystems.signalservice.internal.websocket.ShadowingWebSocketConnection]
+ */
+class DefaultWebSocketShadowingBridge(private val context: Application) : WebSocketShadowingBridge {
+  private val store: InternalValues = SignalStore.internalValues()
+
+  override fun writeStatsSnapshot(bytes: ByteArray) {
+    store.setWebSocketShadowingStats(bytes)
+  }
+
+  override fun readStatsSnapshot(): ByteArray? {
+    return store.getWebSocketShadowingStats(null)
+  }
+
+  override fun triggerFailureNotification(message: String) {
+    if (!FeatureFlags.internalUser()) {
+      return
+    }
+    val notification: Notification = NotificationCompat.Builder(context, NotificationChannels.getInstance().FAILURES)
+      .setSmallIcon(R.drawable.ic_notification)
+      .setContentTitle("[Internal-only] $message")
+      .setContentText("Tap to send a debug log")
+      .setContentIntent(
+        PendingIntent.getActivity(
+          context,
+          0,
+          Intent(context, SubmitDebugLogActivity::class.java),
+          PendingIntentFlags.mutable()
+        )
+      )
+      .build()
+
+    NotificationManagerCompat.from(context).notify(NotificationIds.INTERNAL_ERROR, notification)
+  }
+}

app/src/main/java/org/thoughtcrime/securesms/util/FeatureFlags.java

@@ -130,6 +130,7 @@ public final class FeatureFlags {
   private static final String REGISTRATION_V2                   = "android.registration.v2";
   private static final String LIBSIGNAL_WEB_SOCKET_ENABLED      = "android.libsignalWebSocketEnabled";
   private static final String RESTORE_POST_REGISTRATION         = "android.registration.restorePostRegistration";
+  private static final String LIBSIGNAL_WEB_SOCKET_SHADOW_PCT   = "android.libsignalWebSocketShadowingPercentage";
 
   /**
    * We will only store remote values for flags in this set. If you want a flag to be controllable
@@ -209,7 +210,8 @@ public final class FeatureFlags {
       RX_MESSAGE_SEND,
       LINKED_DEVICE_LIFESPAN_SECONDS,
       CAMERAX_CUSTOM_CONTROLLER,
-      LIBSIGNAL_WEB_SOCKET_ENABLED
+      LIBSIGNAL_WEB_SOCKET_ENABLED,
+      LIBSIGNAL_WEB_SOCKET_SHADOW_PCT
   );
 
   @VisibleForTesting
@@ -755,6 +757,15 @@ public final class FeatureFlags {
     return getBoolean(RESTORE_POST_REGISTRATION, false);
   }
 
+  /**
+   * Percentage [0, 100] of web socket requests that will be "shadowed" by sending
+   * an unauthenticated keep-alive via libsignal-net. Default: 0
+   */
+  public static  int libSignalWebSocketShadowingPercentage() {
+    int value = getInteger(LIBSIGNAL_WEB_SOCKET_SHADOW_PCT, 0);
+    return Math.max(0, Math.min(value, 100));
+  }
+
   /** Only for rendering debug info. */
   public static synchronized @NonNull Map<String, Object> getMemoryValues() {
     return new TreeMap<>(REMOTE_VALUES);