Unpack oversize text messages if possible.

Signal/src/ViewControllers/ConversationView/ConversationViewController.m

@@ -3893,7 +3893,6 @@ typedef NS_ENUM(NSInteger, MessagesRangeSizeMode) {
     //
     // We convert large text messages to attachments
     // which are presented as normal text messages.
-    const NSUInteger kOversizeTextMessageSizeThreshold = 16 * 1024;
     BOOL didAddToProfileWhitelist = [ThreadUtil addThreadToProfileWhitelistIfEmptyContactThread:self.thread];
     TSOutgoingMessage *message;
     if ([text lengthOfBytesUsingEncoding:NSUTF8StringEncoding] >= kOversizeTextMessageSizeThreshold) {

SignalMessaging/attachments/SharingThreadPickerViewController.m

@@ -193,39 +193,63 @@ NS_ASSUME_NONNULL_BEGIN
     }
 #endif
 
-    void (^sendCompletion)(NSError *_Nullable, TSOutgoingMessage *message) = ^(
+    void (^sendCompletion)(NSError *_Nullable, TSOutgoingMessage *) = ^(
         NSError *_Nullable error, TSOutgoingMessage *message) {
-        AssertIsOnMainThread();
-
-        if (error) {
-            [fromViewController
-                dismissViewControllerAnimated:YES
-                                   completion:^(void) {
-                                       DDLogInfo(@"%@ Sending attachment failed with error: %@", self.logTag, error);
-                                       [self showSendFailureAlertWithError:error
-                                                                   message:message
-                                                        fromViewController:fromViewController];
-                                   }];
-            return;
-        }
 
-        DDLogInfo(@"%@ Sending attachment succeeded.", self.logTag);
-        [self.shareViewDelegate shareViewWasCompleted];
+        dispatch_async(dispatch_get_main_queue(), ^{
+            if (error) {
+                [fromViewController
+                    dismissViewControllerAnimated:YES
+                                       completion:^(void) {
+                                           DDLogInfo(
+                                               @"%@ Sending attachment failed with error: %@", self.logTag, error);
+                                           [self showSendFailureAlertWithError:error
+                                                                       message:message
+                                                            fromViewController:fromViewController];
+                                       }];
+                return;
+            }
+
+            DDLogInfo(@"%@ Sending attachment succeeded.", self.logTag);
+            [self.shareViewDelegate shareViewWasCompleted];
+        });
     };
 
-    [fromViewController presentViewController:progressAlert
-                                     animated:YES
-                                   completion:^(void) {
-                                       __block TSOutgoingMessage *outgoingMessage =
-                                           [ThreadUtil sendMessageWithAttachment:self.attachment
-                                                                        inThread:self.thread
-                                                                   messageSender:self.messageSender
-                                                                      completion:^(NSError *_Nullable error) {
-                                                                          sendCompletion(error, outgoingMessage);
-                                                                      }];
-
-                                       self.outgoingMessage = outgoingMessage;
+    [fromViewController
+        presentViewController:progressAlert
+                     animated:YES
+                   completion:^(void) {
+                       __block TSOutgoingMessage *outgoingMessage = nil;
+                       if (self.attachment.isOversizeText
+                           && self.attachment.dataLength <= kOversizeTextMessageSizeThreshold) {
+                           // Try to unpack oversize text messages and send them as regular
+                           // text messages if possible.
+                           NSData *_Nullable data = self.attachment.data;
+                           if (!data) {
+                               DDLogError(@"%@ couldn't load data for oversize text attachment", self.logTag);
+                           } else {
+                               NSString *messageText =
+                                   [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
+                               outgoingMessage = [ThreadUtil sendMessageWithText:messageText
+                                   inThread:self.thread
+                                   messageSender:self.messageSender
+                                   success:^{
+                                       sendCompletion(nil, outgoingMessage);
+                                   }
+                                   failure:^(NSError *_Nonnull error) {
+                                       sendCompletion(error, outgoingMessage);
                                    }];
+                               return;
+                           }
+                       }
+
+                       outgoingMessage = [ThreadUtil sendMessageWithAttachment:self.attachment
+                                                                      inThread:self.thread
+                                                                 messageSender:self.messageSender
+                                                                    completion:^(NSError *_Nullable error) {
+                                                                        sendCompletion(error, outgoingMessage);
+                                                                    }];
+                   }];
 }
 
 - (void)showSendFailureAlertWithError:(NSError *)error

SignalServiceKit/src/Messages/OWSMessageSender.h

@@ -1,11 +1,13 @@
 //
-//  Copyright (c) 2017 Open Whisper Systems. All rights reserved.
+//  Copyright (c) 2018 Open Whisper Systems. All rights reserved.
 //
 
 #import "DataSource.h"
 
 NS_ASSUME_NONNULL_BEGIN
 
+extern const NSUInteger kOversizeTextMessageSizeThreshold;
+
 @class ContactsUpdater;
 @class OWSBlockingManager;
 @class OWSUploadingService;

SignalServiceKit/src/Messages/OWSMessageSender.m

@@ -45,6 +45,8 @@
 
 NS_ASSUME_NONNULL_BEGIN
 
+const NSUInteger kOversizeTextMessageSizeThreshold = 16 * 1024;
+
 void AssertIsOnSendingQueue()
 {
 #ifdef DEBUG
@@ -383,6 +385,9 @@ NSString *const OWSMessageSenderRateLimitedException = @"RateLimitedException";
                failure:(void (^)(NSError *error))failureHandler
 {
     OWSAssert(message);
+    if (message.body.length > 0) {
+        OWSAssert([message.body lengthOfBytesUsingEncoding:NSUTF8StringEncoding] <= kOversizeTextMessageSizeThreshold);
+    }
 
     dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
         // This method will use a read/write transaction. This transaction

SignalShareExtension/ShareViewController.swift

@@ -584,6 +584,9 @@ public class ShareViewController: UINavigationController, ShareViewDelegate, SAE
             var rawDataSource: DataSource?
             if utiType == (kUTTypeURL as String) {
                 // Share URLs as oversize text messages whose text content is the URL.
+                //
+                // NOTE: SharingThreadPickerViewController will try to unpack them
+                //       and send them as normal text messages if possible.
                 let urlString = url.absoluteString
                 rawDataSource = DataSourceValue.dataSource(withOversizeText:urlString)
             } else {