Refine handling of unsafe filename characters.

Signal/src/ViewControllers/DebugUI/DebugUIMessages.m

@@ -284,6 +284,10 @@ NS_ASSUME_NONNULL_BEGIN
                         actionBlock:^{
                             [DebugUIMessages testZalgoTextInThread:thread];
                         }],
+        [OWSTableItem itemWithTitle:@"Test Directional Filenames"
+                        actionBlock:^{
+                            [DebugUIMessages testDirectionalFilenamesInThread:thread];
+                        }],
     ] mutableCopy];
     if ([thread isKindOfClass:[TSContactThread class]]) {
         TSContactThread *contactThread = (TSContactThread *)thread;
@@ -1684,6 +1688,32 @@ NS_ASSUME_NONNULL_BEGIN
         }];
 }
 
++ (void)testDirectionalFilenamesInThread:(TSThread *)thread
+{
+    for (NSString *filename in @[
+             @"a_test\u202Dabc.exe",
+             @"b_test\u202Eabc.exe",
+             @"c_testabc.exe",
+         ]) {
+        OWSMessageSender *messageSender = [Environment current].messageSender;
+        NSString *utiType = (NSString *)kUTTypeData;
+        const NSUInteger kDataLength = 32;
+        DataSource *_Nullable dataSource =
+            [DataSourceValue dataSourceWithData:[self createRandomNSDataOfSize:kDataLength] utiType:utiType];
+        [dataSource setSourceFilename:filename];
+        SignalAttachment *attachment =
+            [SignalAttachment attachmentWithDataSource:dataSource dataUTI:utiType imageQuality:TSImageQualityOriginal];
+
+        OWSAssert(attachment);
+        if ([attachment hasError]) {
+            DDLogError(@"attachment[%@]: %@", [attachment sourceFilename], [attachment errorName]);
+            [DDLog flushLog];
+        }
+        OWSAssert(![attachment hasError]);
+        [ThreadUtil sendMessageWithAttachment:attachment inThread:thread messageSender:messageSender completion:nil];
+    }
+}
+
 @end
 
 NS_ASSUME_NONNULL_END

SignalMessaging/attachments/SignalAttachment.swift

@@ -130,7 +130,7 @@ public class SignalAttachment: NSObject {
 
     @objc
     public var sourceFilename: String? {
-        return dataSource.sourceFilename?.filterStringForDisplay()
+        return dataSource.sourceFilename?.filterFilename()
     }
 
     @objc
@@ -311,7 +311,7 @@ public class SignalAttachment: NSObject {
     @objc
     public var filenameOrDefault: String {
         if let filename = sourceFilename {
-            return filename.filterStringForDisplay()
+            return filename.filterFilename()
         } else {
             let kDefaultAttachmentName = "signal"
 
@@ -335,7 +335,7 @@ public class SignalAttachment: NSObject {
         if let filename = sourceFilename {
             let fileExtension = (filename as NSString).pathExtension
             if fileExtension.count > 0 {
-                return fileExtension.filterStringForDisplay()
+                return fileExtension.filterFilename()
             }
         }
         if isOversizeText {

SignalServiceKit/src/Messages/Attachments/TSAttachment.m

@@ -192,12 +192,12 @@ NSUInteger const TSAttachmentSchemaVersion = 4;
 
 - (nullable NSString *)sourceFilename
 {
-    return _sourceFilename.filterStringForDisplay;
+    return _sourceFilename.filterFilename;
 }
 
 - (NSString *)contentType
 {
-    return _contentType.filterStringForDisplay;
+    return _contentType.filterFilename;
 }
 
 @end

SignalServiceKit/src/Messages/Interactions/TSOutgoingMessage.m

@@ -529,6 +529,7 @@ NSString *const kTSOutgoingMessageSentRecipientAll = @"kTSOutgoingMessageSentRec
     [builder setId:attachmentStream.serverId];
     OWSAssert(attachmentStream.contentType.length > 0);
     [builder setContentType:attachmentStream.contentType];
+    DDLogVerbose(@"%@ Sending attachment with filename: '%@'", self.logTag, filename);
     [builder setFileName:filename];
     [builder setSize:attachmentStream.byteCount];
     [builder setKey:attachmentStream.encryptionKey];

SignalServiceKit/src/Messages/OWSReadReceiptManager.m

@@ -357,7 +357,7 @@ NSString *const OWSReadReceiptManagerAreReadReceiptsEnabled = @"areReadReceiptsE
                                                                                        ofClass:[TSOutgoingMessage class]
                                                                                withTransaction:transaction];
                 if (messages.count > 1) {
-                    OWSFail(@"%@ More than one matching message with timestamp: %llu.", self.logTag, sentTimestamp);
+                    DDLogError(@"%@ More than one matching message with timestamp: %llu.", self.logTag, sentTimestamp);
                 }
                 if (messages.count > 0) {
                     // TODO: We might also need to "mark as read by recipient" any older messages

SignalServiceKit/src/Util/DataSource.m

@@ -80,7 +80,7 @@ NS_ASSUME_NONNULL_BEGIN
 
 - (void)setSourceFilename:(nullable NSString *)sourceFilename
 {
-    _sourceFilename = sourceFilename.filterStringForDisplay;
+    _sourceFilename = sourceFilename.filterFilename;
 }
 
 @end

SignalServiceKit/src/Util/NSString+SSK.h

@@ -10,6 +10,8 @@ NS_ASSUME_NONNULL_BEGIN
 
 - (NSString *)filterStringForDisplay;
 
+- (NSString *)filterFilename;
+
 - (BOOL)isValidE164;
 
 @end

SignalServiceKit/src/Util/NSString+SSK.m

@@ -144,7 +144,7 @@ NS_ASSUME_NONNULL_BEGIN
     return [filteredForIndic copy];
 }
 
-+ (NSCharacterSet *)unsafeCharacterSet
++ (NSCharacterSet *)unsafeFilenameCharacterSet
 {
     static NSCharacterSet *characterSet;
     static dispatch_once_t onceToken;
@@ -160,9 +160,9 @@ NS_ASSUME_NONNULL_BEGIN
     return characterSet;
 }
 
-- (NSString *)filterUnsafeCharacters
+- (NSString *)filterUnsafeFilenameCharacters
 {
-    NSCharacterSet *unsafeCharacterSet = [[self class] unsafeCharacterSet];
+    NSCharacterSet *unsafeCharacterSet = [[self class] unsafeFilenameCharacterSet];
     NSRange range = [self rangeOfCharacterFromSet:unsafeCharacterSet];
     if (range.location == NSNotFound) {
         return self;
@@ -184,7 +184,12 @@ NS_ASSUME_NONNULL_BEGIN
 
 - (NSString *)filterStringForDisplay
 {
-    return self.ows_stripped.filterForIndicScripts.filterForExcessiveDiacriticals.filterUnsafeCharacters;
+    return self.ows_stripped.filterForIndicScripts.filterForExcessiveDiacriticals;
+}
+
+- (NSString *)filterFilename
+{
+    return self.ows_stripped.filterForIndicScripts.filterForExcessiveDiacriticals.filterUnsafeFilenameCharacters;
 }
 
 - (NSString *)filterForExcessiveDiacriticals