I currently have a method that sends data through Bonjour. The problem is that my data is limited to 1000 kB. I know that if I want to send larger data I need to break it in to packets.
But this raises a question of how do I prevent packets from being lost, and ensure all packets are received by the receiver.
I am not good with network and would like to ask you to help me change this simple method to enable larger data transfer.
- (BOOL)sendData:(NSData *)data error:(NSError **)error {
BOOL successful = NO;
if(self.outputStreamHasSpace) {
NSInteger len = [self.outputStream write:[data bytes] maxLength:[data length]];
if(-1 == len) {
// error occured
*error = [[NSError alloc]
initWithDomain:ServerErrorDomain
code:kServerNoSpaceOnOutputStream
userInfo:[[self.outputStream streamError] userInfo]];
} else if(0 == len) {
// stream has reached capacity
*error = [[NSError alloc]
initWithDomain:ServerErrorDomain
code:kServerOutputStreamReachedCapacity
userInfo:[[self.outputStream streamError] userInfo]];
} else {
successful = YES;
}
} else {
*error = [[NSError alloc] initWithDomain:ServerErrorDomain
code:kServerNoSpaceOnOutputStream
userInfo:nil];
}
return successful;
}
Thank you.
You're not sending them over 'Bonjour', you're sending UDP packets to a multicast address. On most networks the maximum frame size is 1500 bytes. Realistically, allowing for headers, vlan tags, etc, you have about 1.3 - 1.4k of data per frame to fill. As the data's going over UDP, controlling the correct reception and ordering of packets is up to you- it's one of the drawbacks of not using TCP ;)
Related
I have the problem that I send an udp Message (broadcast) to a client and get an answer, but this will be displayed two times. When I check the communication an my PC with an UDP listener there is only one message.
May be, someone can give me an info how I can resolve this.
I am using a button to start sending the message!
#import "ViewController.h"
#import "GCDAsyncUdpSocket.h"
#interface ViewController ()
{
long tag;
GCDAsyncUdpSocket *udpSocket;
}
#end
#implementation ViewController
- (void)setupSocket
{ udpSocket = [[GCDAsyncUdpSocket alloc] initWithDelegate:self delegateQueue:dispatch_get_main_queue()];
NSError *error = nil;
if (![udpSocket bindToPort:1000 error:&error])
{
NSLog(#"Error binding: %#", error);
return;
}
if (![udpSocket beginReceiving:&error])
{
NSLog(#"Error receiving: %#", error);
return;
}
[udpSocket enableBroadcast:YES error: &error];
NSLog(#"Ready");
}
- (void)viewDidLoad
{
[super viewDidLoad];
if (udpSocket == nil)
{
[self setupSocket];
}
}
- (void)didReceiveMemoryWarning
{
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}
- (IBAction)send:(id)sender{
NSString *host = #"192.168.2.255";
if ([host length] == 0)
{
NSLog(#"Address required");
return;
}
NSLog(#"%#",host);
int port = 8888;
NSString *msg = #"1,0,1,2";
NSData *data = [msg dataUsingEncoding:NSUTF8StringEncoding];
[udpSocket sendData:data toHost:host port:port withTimeout:-1 tag:tag];
NSLog(#"SENT (%i): %#", (int)tag, msg);
tag++;
}
- (void)udpSocket:(GCDAsyncUdpSocket *)sock didReceiveData:(NSData *)data
fromAddress:(NSData *)address
withFilterContext:(id)filterContext
{
NSString *msg = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
if (msg)
{
NSLog(#"RECV: %#", msg);
tag++;
NSLog(#"%li",tag);
}
else
{
NSString *host = nil;
uint16_t port = 0;
[GCDAsyncUdpSocket getHost:&host port:&port fromAddress:address];
NSLog(#"RECV: Unknown message from: %#:%hu", host, port);
}
}
#end
Here ist the output!
2013-09-11 09:49:00.132 udptest[5145:907] 15
2013-09-11 09:49:08.218 udptest[5145:907] 192.168.2.255
2013-09-11 09:49:08.220 udptest[5145:907] SENT (15): 1,0,1,2
2013-09-11 09:49:08.319 udptest[5145:907] RECV: 0,0,0,0,0,0,0,0
2013-09-11 09:49:08.321 udptest[5145:907] 17
2013-09-11 09:49:08.323 udptest[5145:907] RECV: 0,0,0,0,0,0,0,0
2013-09-11 09:49:08.324 udptest[5145:907] 18
I would be very grateful if someone could help me.
I have the same strange unwanted and unresolved behaviour: "sender" sends one broadcast UDP message and "receiver" gets two messagges.
I've investigated as much as I could and these are my findings:
1) Wireshark gets only one UDP message.
2) udpSocket:didReceiveData:fromAddress:withFilterContext: gets fired two times!
3) Parsing the "address" param with [GCDAsyncUdpSocket getHost:port:fromAddress:] results in host = ::ffff:192.168.1.118 the FIRST time while host = 192.168.1.118 the SECOND time.
Hope it would be helpful in some manner...
EDIT (with a possible SOLUTION)
The FIRST address (see points 2 and 3) is an actual IPv6 address.
So I guess that the udpSocket:didReceiveData:... is fired two times beacuse the first time the sender is the IPv6 address and the second time the sender is the IPv4 address of the same address.
And so my solution is to enable only the IPv4 in the UDP socket:
[udpSocket setIPv4Enabled:YES];
[udpSocket setIPv6Enabled:NO];
Are the response message and the request message same in terms of what they contain. If yes, then here is one scenario that you might be running into. May be the first packet is the broadcast that you are listening for your self and the second packet is the response. To be more precise, when you send a broadcast (pkt p1), then the sender can also get a copy of p1. Next, when the receiver sends a response (pkt p2), then you see the response as well.
So, how do we verify it. You can look at the senders address (UDP provides an option) and then check if it is your address or the address of the other host.
I downloaded WiTap Code From Apple's website. Its for transferring data over local wifi network. I am working in a project to interact as client - server architecture. I am sending NSData from client side to server.
I made 2 projects; one for client and one for server
At client side project, i made following Changes
For that I modified the AppController.m file by adding following method
AppController.m (Client side)
- (void)sendData:(NSData*)pobjData
{
assert(self.streamOpenCount == 2);
if ( [self.outputStream hasSpaceAvailable] )
{
NSInteger bytesWritten;
NSUInteger length = [pobjData length];
bytesWritten = [self.outputStream write:[pobjData bytes] maxLength:[pobjData length]];
NSLog(#"written bytes -> %d",bytesWritten);
}
}
Then by calling this method I send data.
At Server side project, I made following chagnes for that I modified the AppController.m file by modifying following method
AppController.m (Server side)
- (void)stream:(NSStream *)stream handleEvent:(NSStreamEvent)eventCode
{
#pragma unused(stream)
switch(eventCode) {
case NSStreamEventOpenCompleted: {
self.streamOpenCount += 1;
assert(self.streamOpenCount <= 2);
// Once both streams are open we hide the picker and the game is on.
if (self.streamOpenCount == 2) {
[self dismissPicker];
[self.server deregister];
}
} break;
case NSStreamEventHasSpaceAvailable: {
assert(stream == self.outputStream);
// do nothing
} break;
case NSStreamEventHasBytesAvailable:
{
if (stream == self.inputStream)
{
NSInteger bytesRead;
uint32_t buffer[32768];
NSMutableData *_data = [NSMutableData data];
// Pull some data off the network.
bytesRead = [self.inputStream read:buffer maxLength:sizeof(buffer)];
if (bytesRead == -1) {
} else if (bytesRead == 0) {
} else {
// FIXME: Popup an alert
const long long expectedContentLength = bytesRead;
NSUInteger expectedSize = 0;
// expectedContentLength can be represented as NSUInteger, so cast it:
expectedSize = (NSUInteger)expectedContentLength;
[_data appendBytes:buffer length:expectedSize];
NSLog(#"\"Data received has length: %d", _data.length);
[self performSelector:#selector(getData:) withObject:_data afterDelay:1.0];
}
}
}
break;
default:
assert(NO);
// fall through
case NSStreamEventErrorOccurred:
// fall through
case NSStreamEventEndEncountered: {
[self setupForNewGame];
} break;
}
}
and added a method to write the received data as a file
#define kUserDirectoryPath NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES)
-(void)getData:(NSMutableData *)pData
{
NSFileManager *tmpmanager = [NSFileManager defaultManager];
[tmpmanager createFileAtPath:[AppController getDocumentDirectoryPath:[NSString stringWithFormat:#"%#.png",[NSDate date]]] contents:pData attributes:nil];
}
+(NSString*)getDocumentDirectoryPath:(NSString*)pStrPathName
{
NSString *strPath=nil;
if(pStrPathName)
strPath = [[kUserDirectoryPath objectAtIndex:0] stringByAppendingPathComponent:pStrPathName];
return strPath;
}
I convert .png files to NSData and send them from client side to server side. the server downloads the file to Document Directory
The matter is , when i transfer file from client side , it gets downloaded to server side at document directory. Everything works fine in case of tiny files. If file size exceeds to 8kB , file written at document directory gets corrupted.
Kindly help me to be able to send large files.
The problem is that your code doesn't loop to gather all of the available data till the end (or loop to send all data either). So you only ever receive the first buffer of data. If the image is small then that works ok, if the image is bigger then it never will.
You need to write the code so that it keeps sending when there is buffer space until all data is sent and keep reading data (into an NSMutableData instance variable, not a local variable) until the end of the stream is reached.
You can use AsyncSocket which can be downloaded from
https://github.com/roustem/AsyncSocket ,
this is an objective-c wrapper build on CFSocket and CFNetwork, it can handle large amount of data transfer with TCP/UDP protocol on local wifi.
You can find the wiki here https://github.com/darkseed/cocoaasyncsocket/wiki/iPhone
The class is very simple and easy to implement.Give it a try
You have make a web service from where you need to put IP address of the system, Where you want to send the file and after that when you can connected with the entered IP address you can send the file in Base64 and NSData format.
It's my first specific question here on stackoverflow, cause I couldn't found any helpful solutions for my problem yet.
I need a low level socket connection between my iPhone and OSX Workstation (as TCP Server), to interchange some media data like pictures or audio files. So I think AsyncSockets is a good choise to get this to work. I've often used it for some tiny byte communication.
My Problem is, that I want to use a kind of a header/protocol to tell the server how much data bytes are still in pipe.
A simple communication like "hello world" is working fine, so there are no connection problems.
The mobile device (that wants to send a picture) does the following.
[self setHost:#"172.22.42.207"];
self.socket = [[[AsyncSocket alloc] initWithDelegate:self] autorelease];
NSError *err = nil;
[[self socket] connectToHost:self.host onPort:5009 error:&err];
...
NSData *t = UIImagePNGRepresentation(test);
NSString *header = [NSString stringWithFormat:#"%i", t.length];
NSMutableData *headerData = [[header dataUsingEncoding:NSUTF8StringEncoding] mutableCopy];
[headerData appendBytes:[AsyncSocket CRLFData] length:[[AsyncSocket CRLFData] length]];
[[self socket] writeData:headerData withTimeout:-1 tag:0];
The server is listening that way:
AsyncSocket *s = [[AsyncSocket alloc] initWithDelegate:self];
NSError *err = nil;
[s acceptOnPort:5009 error:&err];
if(err)
NSLog(#"EPIC FAIL...\n%#", err);
....
- (void)onSocket:(AsyncSocket *)sock didAcceptNewSocket:(AsyncSocket *)newSocket
{
NSLog(#"%s", __PRETTY_FUNCTION__);
[newSocket readDataToData:[AsyncSocket CRLFData] withTimeout:-1 tag:0];
}
Now: If I use readData:withTimeout:tag it all works like a charm. But once I change the code to readDataToData:withTimeout:tag, to split the header from the other content, the onSocket:didConnectToHost:port: method is never called. Here are some pretty function logs (I placed them in every delegate method)
Client side:
2012-01-31 13:40:32.962 AVMobile[20643:10703] -[SLViewController onSocket:didConnectToHost:port:]
2012-01-31 13:40:32.964 AVMobile[20643:10703] -[SLViewController onSocket:didWriteDataWithTag:]
Server side:
2012-01-31 13:40:32.961 AVServer[20618:707] -[SLAppDelegate onSocket:didAcceptNewSocket:]
So, next idea... just compare the sending and receiving bytes, so:
Sending: <33333736 35365cba>
Receiving: <33333736 35365cba>
Yeah... now my final question: What am I doing wrong!?
Why isn't it working out for me :)?
Greetings & thanks!
sniperosx
Found a solution:
Just don't use -1 as timeout.
With -1 timeout the AsyncSocket is reading data until the other side is closing the connection, so in this range no delegate method is called.
Cheerz
sniperosx
[Closed]
I'm trying to send files over a bluetooth connection.
I've got this to work thanks to my previous post, but the method wasn't memory efficient.
The whole file was loaded into memory before it was sent, and this created problems (and crashed the app) for files > ~20 MB. So I've come up with a new method of only reading parts of the file I need at a specific time, creating packets from the data, sending them and repeating the process for each 8KB chunk of the file.
So I made a class method that generates the packet, informs the controller that a packet is available (through a protocol) and repeats this process for each packet that's available.
Here's the code for the packet generator:
+ (void)makePacketsFromFile:(NSString *)path withDelegate:(id <filePacketDelegate>)aDelegate {
if (![[NSFileManager defaultManager] fileExistsAtPath:path] || aDelegate == nil) return;
id <filePacketDelegate> delegate;
delegate = aDelegate;
const NSUInteger quanta = 8192;
uint filesize;
NSDictionary *fileAttributes = [[NSFileManager defaultManager] attributesOfItemAtPath:path error:nil];
filesize = [[fileAttributes objectForKey:NSFileSize] intValue];
int numOfPackets = (int)ceil(filesize/quanta);
if (numOfPackets == 0) numOfPackets = 1;
NSLog(#"filesize = %d, numOfPackets = %d or %.3f", filesize, numOfPackets, (float)ceil(filesize/quanta));
NSFileHandle *handle = [NSFileHandle fileHandleForReadingAtPath:path];
int offset = 0;
int counter = 0;
while (counter != (numOfPackets + 1)) {
uint len = (filesize < quanta) ? filesize : quanta;
if (counter == numOfPackets) {
len = filesize - offset;
}
[handle seekToFileOffset:offset];
NSData *fileData = [handle readDataOfLength:len];
file_packet *packet = [[file_packet alloc] initWithFileName:[path lastPathComponent] ofType:0 index:counter];
packet.packetContents = fileData;
[fileData release];
packet.checksum = #"<to be done>";
packet.numberOfPackets = [NSString stringWithFormat:#"%d", numOfPackets];
[delegate packetIsReadyForSending:packet];
[packet release];
offset += quanta;
counter++;
}
[handle closeFile];
}
And receiving and sending the file:
- (void)packetIsReadyForSending:(file_packet *)packet {
NSData *fileData = [packet dataForSending];
[self.connectionSession sendDataToAllPeers:fileData withDataMode:GKSendDataReliable error:nil];
}
- (void)sendFileViaBluetooth {
[file_packet makePacketsFromFile:selectedFilePath withDelegate:self];
}
However, the memory use is quite large. Not what I expected.
I'm a bit stuck on this, as I wouldn't like to restrict bluetooth sharing to files smaller than 20MB.
Any help appreciated.
Edit:
I've been thinking about this for a while and have come to the conclusion that it's not my code that's causing the memory allocation issue, it's GameKit's stack for sending the packets.
I think I'm generating too many packets too fast, and I don't think GameKit is sending them quick enough.
So I am now thinking about a way to see when GameKit has sent a packet, and only generating another one once GameKit confirms it was sent.
There’s one clear memory management issue in your code:
NSData *fileData = [handle readDataOfLength:len];
fileData wasn’t obtained via NARC (a method whose name contains new, alloc, retain, copy), so you don’t own it, hence you don’t release it.
[fileData release];
Oops.
As for the memory use, one thing to consider is that even though you release packet you can’t really tell what’s going on inside -[GKSession sendDataToAllPeers:withDataMode:error:]. It is possible that the method internally creates autoreleased objects that only end up being released after +makePacketsFromFile:withDelegate: has finished executing. I suggest you use a new autorelease pool in every loop iteration:
while (counter != (numOfPackets + 1)) {
NSAutoreleasePool *pool = [NSAutoreleasePool new];
uint len = (filesize < quanta) ? filesize : quanta;
…
counter++;
[pool drain];
}
By doing this, any autoreleased object inside that loop will be effectively released at the end of each loop iteration.
Checkout the NSInputStream. With it you can open a stream and only read out a buffer of bytes at a time.
I'm trying to download several images in response to a single http request. On the server side (java) I'm using oreilly multipart response and I'm getting my datas in my iPhone Simulator in didReceiveData (approximately one call for each image) after a call to didReceiveResponse (approximately one call for each image as well) in my delegate.
The problem is this approximately... Has anyone ever managed to handle correctly multipart/x-mixed-re with iPhone SDK ? If yes what is the best strategy here ? Should I play with the expected length ? on server side ? on client side ? should I wait until I've received everything... mmmh that doesn't even seen enough as the calls to didReceiveData happens in a random order (I'm asking picture1,picture2 and I'm sometimes receiving picture2,picture1 even though the order is respected on server side !). Should i temporize between pictures on server side ?
Or should I drop multipart/x-mixed-replace ? what would be the easiest then ?
That's a lot of questions but I'm really stuck here ! Thanks for you help !
I'm not sure what your final use for the images is, but the intended purpose of the multipart/x-midex-replace content type is for each received part to completely replace the previously received responses. Think of it like frames of a video; only one picture is displayed at a time and the previous ones are discarded.
Temporizing is almost never a foolproof solution. Especially on the iPhone you're going to encounter an unimaginable variety of network situations and relying on a magic number delay between frames will probably still fail some of the time.
Since you have control of the server, I'd recommend dropping the multipart. Make sure when you are sending multiple requests to the server that you don't block the main thread of your iPhone app. Use NSOperations or an alternative HTTP library (like ASIHTTPRequest) to make your image fetch operations asynchronous.
I did that successfully using this code. The important thing is to create 2 buffers to receive your data. If you use only one you will have some double access problems (stream access and jpg CODEC access) and corrupted JPG data.
Do not hesitate to ask me for more details.
- (IBAction)startDowload:(id)sender {
NSURL *url = [NSURL URLWithString:#"http://210.236.173.198/axis-cgi/mjpg/video.cgi?resolution=320x240&fps=5"];
NSMutableURLRequest *req = [NSMutableURLRequest requestWithURL:url];
[req setHTTPMethod:#"GET"];
/*
I create 2 NSMutableData buffers. This points is very important.
I swap them each frame.
*/
receivedData = [[NSMutableData data] retain];
receivedData2 = [[NSMutableData data] retain];
currentData = receivedData;
urlCon = [[NSURLConnection alloc] initWithRequest:req delegate:self];
noImg = YES;
frame = 0;
}
- (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSHTTPURLResponse *)response
{
// this method is called when the server has determined that it
// has enough information to create the NSURLResponse
// it can be called multiple times, for example in the case of a
// redirect, so each time we reset the data.
// receivedData is declared as a method instance elsewhere
UIImage *_i;
#try
{
_i = [UIImage imageWithData:currentData];
}
#catch (NSException * e)
{
NSLog(#"%#",[e description]);
}
#finally
{
}
CGSize _s = [_i size];
[imgView setImage:_i];
[imgView setNeedsDisplay];
[[self view] setNeedsDisplay];
}
/*
Buffers swap
*/
if (currentData == receivedData)
{
currentData = receivedData2;
}
else
{
currentData = receivedData;
}
[currendData setLength:0];
}
- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data
{
// append the new data to the currentData (NSData buffer)
[currendData appendData:data];
}