NSURLSession set header 'Connection' to 'Upgrade' not work - ios

Question

Environment: Mac OS X 10.9, Xcode 5.0.2
I need to create an HTTP request for my mini WebSocket client, example request:
GET / HTTP/1.1
Host: serverwebsocket.com:10080
Upgrade: websocket
Connection: Upgrade
Origin: http://from.com
I've created NSURLSession with NSURLSessionConfiguration and set the headers, and Wireshark shows all header set except Connection which stays keep-alive, but should not.
// Create request based on Sessions
// Create sesson configuretion
NSURLSessionConfiguration* sessionConf = [NSURLSessionConfiguration defaultSessionConfiguration];
// Configure session config
// set header value, detail header websocket on http://learn.javascript.ru/websockets
sessionConf.HTTPAdditionalHeaders = #{#"Upgrade": #"websocket",
#"Connection": #"Upgrage",
#"Origin": #"http://from.com",
#"User-Agent": #"Chrome/36.0.198.5.143"};
// Declare handler block of response
__block void (^handler)(NSData* data, NSURLResponse* response, NSError* error);
handler = ^(NSData* data, NSURLResponse* response, NSError* error)
{
// If receive response from server
if(data)
{
NSString* result = [[[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding] autorelease];
NSLog(#"response data: %#", result);
}
else // something wrong
{
NSString* errorText;
if(error)
{
errorText = [error localizedDescription];
}
else // Generic description
{
errorText = #"Error Interner connection";
}
NSLog(#"Request error: %#",errorText );
}
};
// Create Session
NSURLSession* session = [NSURLSession sessionWithConfiguration:sessionConf];
NSURL* url = [NSURL URLWithString: [_textUrl stringValue]];
[[session dataTaskWithURL:url completionHandler:handler] resume];
How can I change the header for Connection? And I do not want use another websocket library, I want to handle HTTP header in low level.
May, instead of the NSURLSession there are other classes work with network? In NSURLRequest same problem.

Answer 1

For manage HTTP header in low level best way use CFNetwork level. But do not use CFHTTPStream for send/receive of data, because CFHTTPStream support only two state for ‘Connection’ header: ‘keep-alive’ and ‘close’. See in file https://opensource.apple.com/source/CFNetwork/CFNetwork-128/HTTP/CFHTTPStream.c function ‘extern void cleanUpRequest()’.
Solution:
1 Create and customize request by CFHTTPMessageRef and CFHTTPMessageSetHeaderFieldValue
2 Convert request to raw data
3 Send/receive raw data uses NSOutputStream and NSInputStream
This is a minimal example send/receive HTTP WebSocket message in CFNetwork level:
#import "AppDelegate.h"
#implementation AppDelegate
NSInputStream* inputStream;
NSOutputStream* outputStream;
NSMutableData* inputBuffer; // This data receive from server
NSMutableData* outputBuffer; // This data send to server
- (IBAction)btnSend:(id)sender
{
NSURL* url = [NSURL URLWithString: [_textUrl stringValue]];
if( !outputBuffer)
{
outputBuffer = [[NSMutableData alloc] init];
}
///////////////////////////////////////////////////////////////
/////////////// Create GET request uses CFNetwork level
CFHTTPMessageRef request = CFHTTPMessageCreateRequest(kCFAllocatorDefault, CFSTR("GET"), (__bridge CFURLRef)url, kCFHTTPVersion1_1);
// Set Host header
CFHTTPMessageSetHeaderFieldValue(request, CFSTR("Host"), (__bridge CFStringRef)(url.port ? [NSString stringWithFormat:#"%#:%#", url.host, url.port] : url.host));
CFHTTPMessageSetHeaderFieldValue(request, CFSTR("User-Agent"), CFSTR("Chrome/36.0.198.5.143"));
CFHTTPMessageSetHeaderFieldValue(request, CFSTR("Pragma"), CFSTR("no-cache"));
CFHTTPMessageSetHeaderFieldValue(request, CFSTR("Cache-Control"), CFSTR("no-cache"));
// Set special headers for websocket, detail on http://learn.javascript.ru/websockets
CFHTTPMessageSetHeaderFieldValue(request, CFSTR("Upgrade"), CFSTR("websocket"));
CFHTTPMessageSetHeaderFieldValue(request, CFSTR("Connection"), CFSTR("Upgrade"));
NSString* origin = #"http://from.com";
CFHTTPMessageSetHeaderFieldValue(request, CFSTR("Origin"), (__bridge CFStringRef)origin);
CFHTTPMessageSetHeaderFieldValue(request, CFSTR("Sec-WebSocket-Protocol"), CFSTR("SIP"));
CFHTTPMessageSetHeaderFieldValue(request, CFSTR("Sec-WebSocket-Key"), CFSTR("yuPCDHanXBphfIH83e4JVw=="));
CFHTTPMessageSetHeaderFieldValue(request, CFSTR("Sec-WebSocket-Version"), CFSTR("13"));
CFHTTPMessageSetHeaderFieldValue(request, CFSTR("Sec-WebSocket-Extensions"), CFSTR("permessage-deflate; client_max_window_bits, x-webkit-deflate-frame"));
// Convert request to raw data
NSData* rawHttpMessage = CFBridgingRelease(CFHTTPMessageCopySerializedMessage(request));
[outputBuffer appendData:rawHttpMessage];
CFRelease(request);
/////////////////////////////////////////////////////////////////
/////////////// Customize stream for sending/receive data
CFReadStreamRef readStream;
CFWriteStreamRef writeStream;
CFStreamCreatePairWithSocketToHost(NULL, (__bridge CFStringRef)url.host, [url.port intValue],
&readStream, &writeStream);
inputStream = (__bridge_transfer NSInputStream*)readStream;
outputStream = (__bridge_transfer NSOutputStream*)writeStream;
[inputStream setDelegate:self]; // Activate stream event handler
[outputStream setDelegate:self]; // Activate stream event handler
[inputStream scheduleInRunLoop:[NSRunLoop currentRunLoop] forMode:NSDefaultRunLoopMode];
[outputStream scheduleInRunLoop:[NSRunLoop currentRunLoop] forMode:NSDefaultRunLoopMode];
[inputStream open];
[outputStream open];
[inputStream retain];
[outputStream retain];
}
// Handler of event for NSInputStream and NSOutputStream
// Detail see: https://developer.apple.com/library/ios/documentation/Cocoa/Conceptual/Streams/Articles/NetworkStreams.html
-(void)stream:(NSStream*)stream handleEvent:(NSStreamEvent)eventCode
{
switch (eventCode)
{
case NSStreamEventHasSpaceAvailable: // when outputstream can send data
if( stream == outputStream)
{
//NSLog(#"Send data [%lu]", [outputBuffer length]);
[outputStream write:[outputBuffer bytes] maxLength:[outputBuffer length]]; // Send data
// Close output stream when all data sent
[outputStream close];
[outputStream removeFromRunLoop:[NSRunLoop currentRunLoop] forMode:NSDefaultRunLoopMode];
[outputStream release];
outputStream = nil;
[outputBuffer release];
outputBuffer = nil;
}
break;
case NSStreamEventHasBytesAvailable: // when inputstream received data
{
const int bufSize = 2048;
if(!inputBuffer)
{
inputBuffer = [[NSMutableData data] retain];
}
uint8_t buf[bufSize];
long len = 0;
len = [inputStream read:buf maxLength:bufSize]; // get data
if(len)
{
[inputBuffer appendBytes:(const void*)buf length:len];
//NSLog(#"Received data from server [%lu]: %#", [inputBuffer length], inputBuffer); // Show in raw format
NSString* rs = [NSString stringWithUTF8String:[inputBuffer bytes]];
NSLog(#"Received data from server [%lu]:\n%#", [inputBuffer length], rs); // Show in string format
}
else
{
NSLog(#"Received data Error[%li]: %#",(long)[inputStream.streamError code], [inputStream.streamError localizedDescription]);
}
// Close inputStream stream when all data receive
[inputStream close];
[inputStream removeFromRunLoop:[NSRunLoop currentRunLoop] forMode:NSDefaultRunLoopMode];
[inputStream release];
inputStream = nil;
[inputBuffer release];
inputBuffer = nil;
}
break;
case NSStreamEventErrorOccurred: // when error of transmited data
if( stream == outputStream)
{
NSError* error = [stream streamError];
NSLog(#"Error sending data [%li]: %#",(long)[error code], [error localizedDescription]);
}
else if( stream == inputStream)
{
NSError* error = [stream streamError];
NSLog(#"Error receive data [%li]: %#",(long)[error code], [error localizedDescription]);
}
break;
case NSStreamEventEndEncountered: // this is not work ;)
if( stream == outputStream)
{
NSLog(#"outputStream End");
}
else if( stream == inputStream)
{
NSLog(#"inputputStream End");
}
break;
}
}
#end
This sample send WebSocket request and receive WeSocket response:
WebSocket request to server:
GET / HTTP/1.1
Host: serverwebsocket.com:10080
Upgrade: websocket
Connection: Upgrade
Origin: http://from.com
Sec-WebSocket-Protocol:SIP
Sec-WebSocket-Key: yuPCDHanXBphfIH83e4JVw==
Sec-WebSocket-Version: 13
WebSocket response from server:
HTTP/1.1 101 Switching Protocols
Content-Length: 0
Upgrade: websocket
Connection: Upgrade
Sec-WebSocket-Accept: mEgcu0WkPuU6yMRtyUl/C+X8zJE=
Sec-WebSocket-Protocol: sip
Sec-WebSocket-Version: 13

Answer 2

For one thing
#"Connection": #"Upgrage"
should probably be
#"Connection": #"Upgrade"