Enforce a configurable max envelope size.

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

@@ -99,7 +99,8 @@ public class ApplicationDependencyProvider implements ApplicationDependencies.Pr
                                             Optional.fromNullable(IncomingMessageObserver.getUnidentifiedPipe()),
                                             Optional.of(new SecurityEventListener(context)),
                                             provideClientZkOperations().getProfileOperations(),
-                                            SignalExecutors.newCachedBoundedExecutor("signal-messages", 1, 16));
+                                            SignalExecutors.newCachedBoundedExecutor("signal-messages", 1, 16),
+                                            FeatureFlags.maxEnvelopeSize());
   }
 
   @Override

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

@@ -60,6 +60,7 @@ public final class FeatureFlags {
   public  static final String RESEARCH_MEGAPHONE_1         = "research.megaphone.1";
   public  static final String MODERN_PROFILE_SHARING       = "android.modernProfileSharing";
   private static final String VIEWED_RECEIPTS              = "android.viewed.receipts";
+  private static final String MAX_ENVELOPE_SIZE            = "android.maxEnvelopeSize";
 
   /**
    * We will only store remote values for flags in this set. If you want a flag to be controllable
@@ -77,7 +78,8 @@ public final class FeatureFlags {
       CLIENT_EXPIRATION,
       RESEARCH_MEGAPHONE_1,
       MODERN_PROFILE_SHARING,
-      VIEWED_RECEIPTS
+      VIEWED_RECEIPTS,
+      MAX_ENVELOPE_SIZE
   );
 
   /**
@@ -245,13 +247,16 @@ public final class FeatureFlags {
     return getBoolean(MODERN_PROFILE_SHARING, false);
   }
 
-  /**
-   * Whether the user should display the content revealed dot in voice notes.
-   */
+  /** Whether the user should display the content revealed dot in voice notes. */
   public static boolean viewedReceipts() {
     return getBoolean(VIEWED_RECEIPTS, false);
   }
 
+  /** The max size envelope that is allowed to be sent. */
+  public static int maxEnvelopeSize() {
+    return getInteger(MAX_ENVELOPE_SIZE, 0);
+  }
+
   /** Only for rendering debug info. */
   public static synchronized @NonNull Map<String, Object> getMemoryValues() {
     return new TreeMap<>(REMOTE_VALUES);

libsignal/service/src/main/java/org/whispersystems/signalservice/api/ContentTooLargeException.java

@@ -0,0 +1,7 @@
+package org.whispersystems.signalservice.api;
+
+public class ContentTooLargeException extends IllegalStateException {
+  public ContentTooLargeException(long size) {
+    super("Too large! Size: " + size + " bytes");
+  }
+}

libsignal/service/src/main/java/org/whispersystems/signalservice/api/SignalServiceMessageSender.java

@@ -126,6 +126,7 @@ public class SignalServiceMessageSender {
   private final AtomicBoolean                                       isMultiDevice;
 
   private final ExecutorService                                     executor;
+  private final int                                                 maxEnvelopeSize;
 
   /**
    * Construct a SignalServiceMessageSender.
@@ -149,7 +150,7 @@ public class SignalServiceMessageSender {
                                     ClientZkProfileOperations clientZkProfileOperations,
                                     ExecutorService executor)
   {
-    this(urls, new StaticCredentialsProvider(uuid, e164, password, null), store, signalAgent, isMultiDevice, pipe, unidentifiedPipe, eventListener, clientZkProfileOperations, executor);
+    this(urls, new StaticCredentialsProvider(uuid, e164, password, null), store, signalAgent, isMultiDevice, pipe, unidentifiedPipe, eventListener, clientZkProfileOperations, executor, 0);
   }
 
   public SignalServiceMessageSender(SignalServiceConfiguration urls,
@@ -161,7 +162,8 @@ public class SignalServiceMessageSender {
                                     Optional<SignalServiceMessagePipe> unidentifiedPipe,
                                     Optional<EventListener> eventListener,
                                     ClientZkProfileOperations clientZkProfileOperations,
-                                    ExecutorService executor)
+                                    ExecutorService executor,
+                                    int maxEnvelopeSize)
   {
     this.socket           = new PushServiceSocket(urls, credentialsProvider, signalAgent, clientZkProfileOperations);
     this.store            = store;
@@ -171,6 +173,7 @@ public class SignalServiceMessageSender {
     this.isMultiDevice    = new AtomicBoolean(isMultiDevice);
     this.eventListener    = eventListener;
     this.executor         = executor != null ? executor : Executors.newSingleThreadExecutor();
+    this.maxEnvelopeSize  = maxEnvelopeSize;
   }
 
   /**
@@ -698,7 +701,13 @@ public class SignalServiceMessageSender {
 
     builder.setTimestamp(message.getTimestamp());
 
-    return container.setDataMessage(builder).build().toByteArray();
+    byte[] content = container.setDataMessage(builder).build().toByteArray();
+
+    if (maxEnvelopeSize > 0 && content.length > maxEnvelopeSize) {
+      throw new ContentTooLargeException(content.length);
+    }
+
+    return content;
   }
 
   private byte[] createCallContent(SignalServiceCallMessage callMessage) {