Honor attachment filenames.

// FREEBIE

src/Messages/Attachments/OWSAttachmentsProcessor.m

@@ -75,7 +75,8 @@ NS_ASSUME_NONNULL_BEGIN
                                                                                  key:attachmentProto.key
                                                                               digest:digest
                                                                          contentType:attachmentProto.contentType
-                                                                               relay:relay];
+                                                                               relay:relay
+                                                                            filename:attachmentProto.fileName];
 
         [attachmentIds addObject:pointer.uniqueId];
 

src/Messages/Attachments/TSAttachmentPointer.h

@@ -21,9 +21,11 @@ typedef NS_ENUM(NSUInteger, TSAttachmentPointerState) {
                              key:(NSData *)key
                           digest:(nullable NSData *)digest
                      contentType:(NSString *)contentType
-                           relay:(NSString *)relay NS_DESIGNATED_INITIALIZER;
+                           relay:(NSString *)relay
+                        filename:(nullable NSString *)filename NS_DESIGNATED_INITIALIZER;
 
 @property (nonatomic, readonly) NSString *relay;
+@property (nonatomic, readonly, nullable) NSString *filename;
 @property (atomic) TSAttachmentPointerState state;
 
 // Though now required, `digest` may be null for pre-existing records or from

src/Messages/Attachments/TSAttachmentPointer.m

@@ -30,6 +30,7 @@ NS_ASSUME_NONNULL_BEGIN
                           digest:(nullable NSData *)digest
                      contentType:(NSString *)contentType
                            relay:(NSString *)relay
+                        filename:(nullable NSString *)filename
 {
     self = [super initWithServerId:serverId encryptionKey:key contentType:contentType];
     if (!self) {
@@ -39,6 +40,7 @@ NS_ASSUME_NONNULL_BEGIN
     _digest = digest;
     _state = TSAttachmentPointerStateEnqueued;
     _relay = relay;
+    _filename = filename;
 
     return self;
 }

src/Messages/Attachments/TSAttachmentStream.h

@@ -24,6 +24,8 @@ NS_ASSUME_NONNULL_BEGIN
 // This only applies for attachments being uploaded.
 @property (atomic) BOOL isUploaded;
 
+@property (nonatomic, readonly, nullable) NSString *filename;
+
 #if TARGET_OS_IPHONE
 - (nullable UIImage *)image;
 #endif

src/Messages/Attachments/TSAttachmentStream.m

@@ -42,6 +42,7 @@ NS_ASSUME_NONNULL_BEGIN
     // state, but this constructor is used only for new incoming
     // attachments which don't need to be uploaded.
     _isUploaded = YES;
+    _filename = pointer.filename;
 
     return self;
 }
@@ -115,6 +116,7 @@ NS_ASSUME_NONNULL_BEGIN
 {
     return [MIMETypeUtil filePathForAttachment:self.uniqueId
                                     ofMIMEType:self.contentType
+                                      filename:self.filename
                                       inFolder:[[self class] attachmentsFolder]];
 }
 

src/Messages/DeviceSyncing/OWSSyncContactsMessage.m

@@ -1,4 +1,6 @@
-//  Copyright © 2016 Open Whisper Systems. All rights reserved.
+//
+//  Copyright (c) 2017 Open Whisper Systems. All rights reserved.
+//
 
 #import "OWSSyncContactsMessage.h"
 #import "Contact.h"
@@ -39,7 +41,7 @@ NS_ASSUME_NONNULL_BEGIN
     }
 
     OWSSignalServiceProtosAttachmentPointer *attachmentProto =
-        [self buildAttachmentProtoForAttachmentId:self.attachmentIds[0]];
+        [self buildAttachmentProtoForAttachmentId:self.attachmentIds[0] filename:nil];
 
     OWSSignalServiceProtosSyncMessageContactsBuilder *contactsBuilder =
         [OWSSignalServiceProtosSyncMessageContactsBuilder new];

src/Messages/DeviceSyncing/OWSSyncGroupsMessage.m

@@ -1,4 +1,6 @@
-//  Copyright © 2016 Open Whisper Systems. All rights reserved.
+//
+//  Copyright (c) 2017 Open Whisper Systems. All rights reserved.
+//
 
 #import "OWSSyncGroupsMessage.h"
 #import "NSDate+millisecondTimeStamp.h"
@@ -25,7 +27,7 @@ NS_ASSUME_NONNULL_BEGIN
             (unsigned long)self.attachmentIds.count);
     }
     OWSSignalServiceProtosAttachmentPointer *attachmentProto =
-        [self buildAttachmentProtoForAttachmentId:self.attachmentIds[0]];
+        [self buildAttachmentProtoForAttachmentId:self.attachmentIds[0] filename:nil];
 
     OWSSignalServiceProtosSyncMessageGroupsBuilder *groupsBuilder =
         [OWSSignalServiceProtosSyncMessageGroupsBuilder new];

src/Messages/Interactions/TSMessage.h

@@ -23,6 +23,7 @@ typedef NS_ENUM(NSInteger, TSGroupMetaMessage) {
 @interface TSMessage : TSInteraction
 
 @property (nonatomic, readonly) NSMutableArray<NSString *> *attachmentIds;
+// A map of attachment id-to-filename.
 @property (nullable, nonatomic) NSString *body;
 @property (nonatomic) TSGroupMetaMessage groupMetaMessage;
 @property (nonatomic) uint32_t expiresInSeconds;

src/Messages/Interactions/TSMessage.m

@@ -128,7 +128,6 @@ static const NSUInteger OWSMessageSchemaVersion = 3;
     }
 
     if (!_attachmentIds) {
-        // previously allowed nil _attachmentIds
         _attachmentIds = [NSMutableArray new];
     }
 

src/Messages/Interactions/TSOutgoingMessage.h

@@ -57,6 +57,7 @@ typedef NS_ENUM(NSInteger, TSOutgoingMessageState) {
 @property BOOL hasSyncedTranscript;
 @property NSString *customMessage;
 @property (atomic, readonly) NSString *mostRecentFailureText;
+@property (nonatomic, readonly) NSMutableDictionary<NSString *, NSString *> *attachmentFilenameMap;
 
 /**
  * Whether the message should be serialized as a modern aka Content, or the old style legacy message.
@@ -94,10 +95,14 @@ typedef NS_ENUM(NSInteger, TSOutgoingMessageState) {
  * @param attachmentId
  *   id of an AttachmentStream containing the meta data used when populating the attachment proto
  *
+ * @param filename
+ *   optional filename of the attachment.
+ *
  * @return
  *      An attachment pointer protobuf suitable for including in various container protobuf builders
  */
-- (OWSSignalServiceProtosAttachmentPointer *)buildAttachmentProtoForAttachmentId:(NSString *)attachmentId;
+- (OWSSignalServiceProtosAttachmentPointer *)buildAttachmentProtoForAttachmentId:(NSString *)attachmentId
+                                                                        filename:(nullable NSString *)filename;
 
 @end
 

src/Messages/Interactions/TSOutgoingMessage.m

@@ -15,7 +15,13 @@ NS_ASSUME_NONNULL_BEGIN
 
 - (instancetype)initWithCoder:(NSCoder *)coder
 {
-    return [super initWithCoder:coder];
+    self = [super initWithCoder:coder];
+    if (self) {
+        if (!_attachmentFilenameMap) {
+            _attachmentFilenameMap = [NSMutableDictionary new];
+        }
+    }
+    return self;
 }
 
 - (instancetype)initWithTimestamp:(uint64_t)timestamp
@@ -86,6 +92,7 @@ NS_ASSUME_NONNULL_BEGIN
     } else {
         self.groupMetaMessage = TSGroupMessageNone;
     }
+    _attachmentFilenameMap = [NSMutableDictionary new];
 
     OWSAssert(self.receivedAtDate);
 
@@ -142,7 +149,8 @@ NS_ASSUME_NONNULL_BEGIN
             case TSGroupMessageNew: {
                 if (gThread.groupModel.groupImage != nil && self.attachmentIds.count == 1) {
                     attachmentWasGroupAvatar = YES;
-                    [groupBuilder setAvatar:[self buildAttachmentProtoForAttachmentId:self.attachmentIds[0]]];
+                    [groupBuilder
+                        setAvatar:[self buildAttachmentProtoForAttachmentId:self.attachmentIds[0] filename:nil]];
                 }
 
                 [groupBuilder setMembersArray:gThread.groupModel.groupMemberIds];
@@ -160,7 +168,8 @@ NS_ASSUME_NONNULL_BEGIN
     if (!attachmentWasGroupAvatar) {
         NSMutableArray *attachments = [NSMutableArray new];
         for (NSString *attachmentId in self.attachmentIds) {
-            [attachments addObject:[self buildAttachmentProtoForAttachmentId:attachmentId]];
+            NSString *filename = self.attachmentFilenameMap[attachmentId];
+            [attachments addObject:[self buildAttachmentProtoForAttachmentId:attachmentId filename:filename]];
         }
         [builder setAttachmentsArray:attachments];
     }
@@ -191,7 +200,10 @@ NS_ASSUME_NONNULL_BEGIN
 }
 
 - (OWSSignalServiceProtosAttachmentPointer *)buildAttachmentProtoForAttachmentId:(NSString *)attachmentId
+                                                                        filename:(nullable NSString *)filename
 {
+    OWSAssert(attachmentId.length > 0);
+
     TSAttachment *attachment = [TSAttachmentStream fetchObjectWithUniqueID:attachmentId];
     if (![attachment isKindOfClass:[TSAttachmentStream class]]) {
         DDLogError(@"Unexpected type for attachment builder: %@", attachment);
@@ -202,6 +214,7 @@ NS_ASSUME_NONNULL_BEGIN
     OWSSignalServiceProtosAttachmentPointerBuilder *builder = [OWSSignalServiceProtosAttachmentPointerBuilder new];
     [builder setId:attachmentStream.serverId];
     [builder setContentType:attachmentStream.contentType];
+    [builder setFileName:filename];
     [builder setKey:attachmentStream.encryptionKey];
     [builder setDigest:attachmentStream.digest];
 

src/Messages/OWSMessageSender.h

@@ -55,6 +55,7 @@ NS_SWIFT_NAME(MessageSender)
  */
 - (void)sendAttachmentData:(NSData *)attachmentData
                contentType:(NSString *)contentType
+                  filename:(nullable NSString *)filename
                  inMessage:(TSOutgoingMessage *)outgoingMessage
                    success:(void (^)())successHandler
                    failure:(void (^)(NSError *error))failureHandler;

src/Messages/OWSMessageSender.m

@@ -437,6 +437,7 @@ NSString *const OWSMessageSenderRateLimitedException = @"RateLimitedException";
 
     [self sendAttachmentData:attachmentData
                  contentType:contentType
+                    filename:nil
                    inMessage:message
                      success:successWithDeleteHandler
                      failure:failureWithDeleteHandler];
@@ -444,6 +445,7 @@ NSString *const OWSMessageSenderRateLimitedException = @"RateLimitedException";
 
 - (void)sendAttachmentData:(NSData *)data
                contentType:(NSString *)contentType
+                  filename:(nullable NSString *)filename
                  inMessage:(TSOutgoingMessage *)message
                    success:(void (^)())successHandler
                    failure:(void (^)(NSError *error))failureHandler
@@ -467,6 +469,9 @@ NSString *const OWSMessageSenderRateLimitedException = @"RateLimitedException";
 
         [attachmentStream save];
         [message.attachmentIds addObject:attachmentStream.uniqueId];
+        if (filename) {
+            message.attachmentFilenameMap[attachmentStream.uniqueId] = filename;
+        }
         [message save];
 
         dispatch_async(dispatch_get_main_queue(), ^{

src/Util/MIMETypeUtil.h

@@ -29,11 +29,11 @@ extern NSString *const OWSMimeTypeUnknownForTests;
 + (BOOL)isVideo:(NSString *)contentType;
 + (BOOL)isAudio:(NSString *)contentType;
 
-+ (NSString *)filePathForAttachment:(NSString *)uniqueId ofMIMEType:(NSString *)contentType inFolder:(NSString *)folder;
+// filename is optional and should not be trusted.
-+ (NSString *)filePathForImage:(NSString *)uniqueId ofMIMEType:(NSString *)contentType inFolder:(NSString *)folder;
++ (NSString *)filePathForAttachment:(NSString *)uniqueId
-+ (NSString *)filePathForVideo:(NSString *)uniqueId ofMIMEType:(NSString *)contentType inFolder:(NSString *)folder;
+                         ofMIMEType:(NSString *)contentType
-+ (NSString *)filePathForAudio:(NSString *)uniqueId ofMIMEType:(NSString *)contentType inFolder:(NSString *)folder;
+                           filename:(nullable NSString *)filename
-+ (NSString *)filePathForAnimated:(NSString *)uniqueId ofMIMEType:(NSString *)contentType inFolder:(NSString *)folder;
+                           inFolder:(NSString *)folder;
 
 + (NSURL *)simLinkCorrectExtensionOfFile:(NSURL *)mediaURL ofMIMEType:(NSString *)contentType;
 

src/Util/MIMETypeUtil.m

@@ -261,7 +261,65 @@ NSString *const OWSMimeTypeUnknownForTests = @"unknown/mimetype";
 
 + (NSString *)filePathForAttachment:(NSString *)uniqueId
                          ofMIMEType:(NSString *)contentType
-                           inFolder:(NSString *)folder {
+                           filename:(nullable NSString *)filename
+                           inFolder:(NSString *)folder
+{
+    NSString *kDefaultFileExtension = @"bin";
+
+    if (filename.length > 0) {
+        NSString *normalizedFilename =
+            [filename stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceCharacterSet]];
+        // Ensure that the filename is a valid filesystem name,
+        // replacing invalid characters with an underscore.
+        for (NSCharacterSet *invalidCharacterSet in @[
+                 [NSCharacterSet whitespaceCharacterSet],
+                 [NSCharacterSet newlineCharacterSet],
+                 [NSCharacterSet illegalCharacterSet],
+                 [NSCharacterSet controlCharacterSet],
+                 [NSCharacterSet characterSetWithCharactersInString:@"<>|\\:()&;?*"],
+             ]) {
+            normalizedFilename = [[normalizedFilename componentsSeparatedByCharactersInSet:invalidCharacterSet]
+                componentsJoinedByString:@"_"];
+        }
+
+        NSString *fileExtension = [[normalizedFilename pathExtension]
+            stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceCharacterSet]];
+        NSString *filenameWithoutExtension = [[[normalizedFilename lastPathComponent] stringByDeletingPathExtension]
+            stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceCharacterSet]];
+
+        // If the filename has not file extension, deduce one
+        // from the MIME type.
+        if (fileExtension.length < 1) {
+            fileExtension = [self fileExtensionForMIMEType:contentType];
+            if (fileExtension.length < 1) {
+                fileExtension = kDefaultFileExtension;
+            }
+        }
+        fileExtension = [fileExtension lowercaseString];
+
+        if (filenameWithoutExtension.length > 0) {
+            // Store the file in a subdirectory whose name is the uniqueId of this attachment,
+            // to avoid collisions between multiple attachments with the same name.
+            NSString *attachmentFolderPath = [folder stringByAppendingPathComponent:uniqueId];
+            NSError *error = nil;
+            BOOL attachmentFolderPathExists = [[NSFileManager defaultManager] fileExistsAtPath:attachmentFolderPath];
+            if (!attachmentFolderPathExists) {
+                [[NSFileManager defaultManager] createDirectoryAtPath:attachmentFolderPath
+                                          withIntermediateDirectories:YES
+                                                           attributes:nil
+                                                                error:&error];
+                if (error) {
+                    DDLogError(@"Failed to create attachment directory: %@", error);
+                    OWSAssert(0);
+                    return nil;
+                }
+            }
+            return [attachmentFolderPath
+                stringByAppendingPathComponent:[NSString
+                                                   stringWithFormat:@"%@.%@", filenameWithoutExtension, fileExtension]];
+        }
+    }
+
     if ([self isVideo:contentType]) {
         return [MIMETypeUtil filePathForVideo:uniqueId ofMIMEType:contentType inFolder:folder];
     } else if ([self isAudio:contentType]) {
@@ -291,7 +349,7 @@ NSString *const OWSMimeTypeUnknownForTests = @"unknown/mimetype";
 
     DDLogError(@"Got asked for path of file %@ which is unsupported", contentType);
     // Use a fallback file extension.
-    return [self filePathForData:uniqueId withFileExtension:@"bin" inFolder:folder];
+    return [self filePathForData:uniqueId withFileExtension:kDefaultFileExtension inFolder:folder];
 }
 
 + (NSURL *)simLinkCorrectExtensionOfFile:(NSURL *)mediaURL ofMIMEType:(NSString *)contentType {