GCDAsyncSocket 未接收到所有传输的数据，缺少最后一个“块”
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【中文标题】GCDAsyncSocket 未接收到所有传输的数据，缺少最后一个“块”【英文标题】：GCDAsyncSocket not receiving all transmitted data, missing last "Chunk" 【发布时间】：2014-04-04 18:38:17 【问题描述】：我正在尝试将一些字符串和图像数据从 python 脚本发送到在 OSX 上运行的目标 C 应用程序。
我正在使用 GCDAsyncSocket 收集传输的数据，并将其附加到 NSMutableData 直到服务器断开连接。然后我正在处理该 NSData 并将其拆分为原始部分。
传输的数据包括以下内容：
ID 字符串，填充到 16 个字节。
图片编号字符串，填充到16字节。
原始图像数据。
终止字符串，填充到 16 个字节。
问题是我没有接收/获取最后一块数据，我最终丢失了 JPEG 图像的结尾，导致图像损坏（尽管大部分显示），并且缺少终止字符串。
这是我使用 GCDAsyncSocket 获取数据并进行处理的代码：
套接字连接：
- (void)socket:(GCDAsyncSocket *)sock didAcceptNewSocket:(GCDAsyncSocket *)newSocket
// This method is executed on the socketQueue (not the main thread)
@synchronized(connectedSockets)
[connectedSockets addObject:newSocket];
NSString *host = [newSocket connectedHost];
UInt16 port = [newSocket connectedPort];
dispatch_async(dispatch_get_main_queue(), ^
@autoreleasepool
[self logInfo:FORMAT(@"Accepted client %@:%hu", host, port)];
);
[newSocket readDataToData:[GCDAsyncSocket CRLFData] withTimeout:-1 tag:0];
收到的套接字数据
- (void)socket:(GCDAsyncSocket *)sock didReadData:(NSData *)data withTag:(long)tag
// This method is executed on the socketQueue (not the main thread)
dispatch_async(dispatch_get_main_queue(), ^
@autoreleasepool
NSLog(@"Thread Data Length is %lu", (unsigned long)[data length]);
if (!imageBuffer)
imageBuffer = [[NSMutableData alloc]init];
[imageBuffer appendData:[data subdataWithRange:NSMakeRange(0, [data length])]];
NSLog(@"Total Data Length is %lu", (unsigned long)[imageBuffer length]);
);
// Echo message back to client
[sock writeData:data withTimeout:-1 tag:ECHO_MSG];
[sock readDataToData:[GCDAsyncSocket CRLFData] withTimeout:-1 tag:0];
套接字断开
- (void)socketDidDisconnect:(GCDAsyncSocket *)sock withError:(NSError *)err
if (sock != listenSocket)
dispatch_async(dispatch_get_main_queue(), ^
@autoreleasepool
[self logInfo:FORMAT(@"Client Disconnected")];
NSData *cameraNumberData;
NSData *imageNumberData;
NSData *imageData;
NSData *endCommandData;
//if ([data length] > 40)
cameraNumberData = [imageBuffer subdataWithRange:NSMakeRange(0, 16)];
imageNumberData = [imageBuffer subdataWithRange:NSMakeRange(16, 16)];
imageData = [imageBuffer subdataWithRange:NSMakeRange(32, [imageBuffer length]-34)];
endCommandData = [imageBuffer subdataWithRange:NSMakeRange([imageBuffer length]-16, 16)];
//
NSString *cameraNumberString = [[NSString alloc] initWithData:cameraNumberData encoding:NSUTF8StringEncoding];
NSString *imageNumberString = [[NSString alloc] initWithData:imageNumberData encoding:NSUTF8StringEncoding];
NSString *endCommandString = [[NSString alloc] initWithData:endCommandData encoding:NSUTF8StringEncoding];
NSImage* image = [[NSImage alloc]initWithData:imageData];
if (cameraNumberString)
NSLog(@"Image recieved from Camera no %@", cameraNumberString);
[self logMessage:cameraNumberString];
else
[self logError:@"Error converting received data into UTF-8 String"];
if (imageNumberString)
NSLog(@"Image is number %@", imageNumberString);
[self logMessage:imageNumberString];
else
[self logError:@"Error converting received data into UTF-8 String"];
if (image)
NSLog(@"We have an image");
[self.imageView setImage:image];
else
[self logError:@"Error converting received data into image"];
if (endCommandString)
NSLog(@"Command String is %@", endCommandString);
[self logMessage:endCommandString];
else
[self logError:@"No command string"];
//self.imageBuffer = nil;
);
@synchronized(connectedSockets)
[connectedSockets removeObject:sock];
我用过wireshark，数据在传输，只是没有通过GCDAsynSocket。
所以，我显然遗漏了一些东西。像这样的套接字编程和数据编码/解码对我来说相对较新，所以我可能是个白痴。
帮助不胜感激！
谢谢
加雷斯
【问题讨论】：
也许你可以使用一些更粗略的传输编码，而不是发送图像的原始字节，例如base64。 嗨，Hyperboreus，这是一个很好的观点，可能会让事情变得更有效率。但是它没有解释为什么字符串的解码失败了？ 没错，它没有回答你的问题（因为我不知道答案），这就是我写评论的原因。 确实，有效点:) 嗨 Hyperboreus，我已经用更多信息更新了我上面的问题，任何进一步的输入将不胜感激！ 【参考方案1】：好的，所以我终于得到了这个工作。它涉及修改 Python 中的传输代码以在数据末尾发送一个完成字符串，并对其进行监视。最大的收获是，每次套接字读取一些数据时，我都需要重新调用 readDataToData: 方法，否则它只会坐在那里等待，而发送套接字也只会坐在那里。
我还必须使用标签重新调用第二个接收，这样我就可以将接收到的数据存储在 NSMutableArray 中正确的 NSMutableData 对象中，否则我无法在第一次接收后知道数据是哪个传输套接字来自，因为 ID 仅在第一条消息的开头。
这里是 didReadData 代码：
- (void)socket:(GCDAsyncSocket *)sock didReadData:(NSData *)data withTag:(long)tag
dispatch_async(dispatch_get_main_queue(), ^
@autoreleasepool
NSInteger cameraNumberNumber = 0;
NSString *cameraNumberString = [[NSString alloc]init];
if (tag > 10)
cameraNumberNumber = tag-11;
DDLogVerbose(@"Second data loop, tag is %ld", tag);
else
NSData *cameraNumberData;
//if ([data length] > 40)
cameraNumberData = [data subdataWithRange:NSMakeRange(0, 16)];
NSString *cameraNumberString = [[NSString alloc] initWithData:cameraNumberData encoding:NSUTF8StringEncoding];
cameraNumberString = [cameraNumberString stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceAndNewlineCharacterSet]];
cameraNumberNumber = [cameraNumberString intValue]-1;
if (cameraNumberNumber+1 <= self.images.count)
if ([self.images objectAtIndex:cameraNumberNumber] == [NSNull null])
image* cameraImage = [[image alloc]init];
[self.images replaceObjectAtIndex: cameraNumberNumber withObject:cameraImage];
image* cameraImage = [self.images objectAtIndex:cameraNumberNumber];
[cameraImage.imageData appendData:[data subdataWithRange:NSMakeRange(0, [data length])]];
cameraImage.cameraNumber = cameraNumberString;
if (!imageBuffer)
imageBuffer = [[NSMutableData alloc]init];
[imageBuffer appendData:[data subdataWithRange:NSMakeRange(0, [data length])]];
DDLogVerbose(@"Total Data Length is %lu", (unsigned long)[imageBuffer length]);
else
DDLogInfo(@"Wrong camera quantity!");
NSAlert *testAlert = [NSAlert alertWithMessageText:@"Wrong camera quantity!"
defaultButton:@"Ok"
alternateButton:nil
otherButton:nil
informativeTextWithFormat:@"We have recieved more images than cameras, please set No.Cameras correctly!"];
[testAlert beginSheetModalForWindow:[self window]
modalDelegate:self
didEndSelector:@selector(stop)
contextInfo:nil];
[sock readDataToData:[@"end" dataUsingEncoding:NSUTF8StringEncoding] withTimeout:-1 tag:cameraNumberNumber + 11];
);
这里是 socketDidDisconnect 代码，这里的很多东西在上下文中没有意义，但它显示了我如何处理接收到的数据。
- (void)socketDidDisconnect:(GCDAsyncSocket *)sock withError:(NSError *)err
if (sock != listenSocket)
dispatch_async(dispatch_get_main_queue(), ^
@autoreleasepool
totalCamerasFetched = [NSNumber numberWithInt:1+[totalCamerasFetched intValue]];
if ([totalCamerasFetched integerValue] >= [numberOfCameras integerValue])
for (image* cameraImage in self.images)
NSData *cameraNumberData;
NSData *imageNumberData;
NSData *imageData;
NSData *endCommandData;
NSInteger cameraNumberNumber = 0;
cameraNumberData = [cameraImage.imageData subdataWithRange:NSMakeRange(0, 16)];
imageNumberData = [cameraImage.imageData subdataWithRange:NSMakeRange(16, 16)];
imageData = [cameraImage.imageData subdataWithRange:NSMakeRange(32, [cameraImage.imageData length]-32)];
endCommandData = [cameraImage.imageData subdataWithRange:NSMakeRange([cameraImage.imageData length]-16, 16)];
NSString *cameraNumberString = [[NSString alloc] initWithData:cameraNumberData encoding:NSUTF8StringEncoding];
cameraNumberString = [cameraNumberString stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceAndNewlineCharacterSet]];
NSString *imageNumberString = [[NSString alloc] initWithData:imageNumberData encoding:NSUTF8StringEncoding];
imageNumberString = [imageNumberString stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceAndNewlineCharacterSet]];
NSString *endCommandString = [[NSString alloc] initWithData:endCommandData encoding:NSUTF8StringEncoding];
NSImage* image = [[NSImage alloc]initWithData:imageData];
cameraNumberNumber = [cameraNumberString intValue]-1;
if (cameraNumberString)
DDLogInfo(@"Image recieved from Camera no %@", cameraNumberString);
else
DDLogError(@"No Camera number in data");
if (imageNumberString)
DDLogInfo(@"Image is number %@", imageNumberString);
else
DDLogError(@"No Image number in data");
if (image)
DDLogVerbose(@"We have an image");
NSString* dataPath = [[NSString alloc]initWithFormat:@"%@/image%@/",self.exportLocation, imageNumberString];
if (![[NSFileManager defaultManager] fileExistsAtPath:dataPath])
NSError* error;
[[NSFileManager defaultManager] createDirectoryAtPath:dataPath withIntermediateDirectories:NO attributes:nil error:&error];
if (error)
DDLogError(@"[%@] ERROR: attempting to write directory for images", [self class]);
NSAssert( FALSE, @"Failed to create directory maybe out of disk space?");
NSString* dataPathVideo = [[NSString alloc]initWithFormat:@"%@/video%@/",self.exportLocation, imageNumberString];
if (![[NSFileManager defaultManager] fileExistsAtPath:dataPathVideo])
NSError* error;
[[NSFileManager defaultManager] createDirectoryAtPath:dataPathVideo withIntermediateDirectories:NO attributes:nil error:&error];
if (error)
DDLogError(@"[%@] ERROR: attempting to write directory for images", [self class]);
NSAssert( FALSE, @"Failed to create directory maybe out of disk space?");
NSString * exportLocationFull = [[NSString alloc]initWithFormat:@"%@/image%@/camera_%@.jpg",self.exportLocation, imageNumberString, cameraNumberString];
DDLogInfo(@"Full export URL = %@", exportLocationFull);
[imageData writeToFile:exportLocationFull atomically:YES];
self.currentSet = [NSNumber numberWithInt:[imageNumberString intValue]];
NSImage* imageToStore = [[NSImage alloc]initWithData:imageData];
[self.imagesToMakeVideo replaceObjectAtIndex: cameraNumberNumber withObject:imageToStore];
else
DDLogError(@"No image loacted in data");
if (endCommandString)
DDLogVerbose(@"Command String is %@", endCommandString);
//[self logMessage:endCommandString];
else
//[self logError:@"No command string"];
self.imageBuffer = nil;
self.totalCamerasFetched = [NSNumber numberWithInt:0];
[self loadandDisplayLatestImages];
[self createVideowithImages:imagesToMakeVideo toLocation:[[NSString alloc]initWithFormat:@"%@/video%@/image_sequence_%@.mov",self.exportLocation, self.currentSet, self.currentSet]];
processing = false;
//end of for loop
);
@synchronized(connectedSockets)
[connectedSockets removeObject:sock];
这也是我如何修改 Python 代码以添加额外的“结束”标签。
def send_media_to(self, ip, port, media_name, media_number, media_dir):
camera_number = self.camera.current_mode['option'].number
sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
sock.connect((ip, port))
try:
sock.send(bytes(str(camera_number).ljust(16), 'utf-8'))
sock.send(bytes(str(media_number).ljust(16), 'utf-8'))
with open(media_dir + media_name, 'rb') as media:
sock.sendall(media.read())
finally:
sock.send(bytes(str("end").ljust(16), 'utf-8'))
sock.close()
希望这可以帮助陷入同样情况的其他人！
【讨论】：
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