SSDP on the iPhone

Question

I need to be able to send out a UDP message and also receive one in order to discover SSDP devices on the network from the iPhone.

I know that I need to send the packet to the multicast address and my HTTP request needs to look something like this:

M-SEARCH * HTTP/1.1
Host: 239.255.255.250:1900
Man: ssdp:discover
Mx: 3
ST: "urn:schemas-upnp-org:device:InternetGatewayDevice:1"

From reading the docs it appears that I can do all this with CFNetwork and despite reading (and re-reading the docs) I am struggling to get started. Can anyone recommend and tutorials or code snippets to get me over the initial learning hump?

I've got the CFNetwork programming guide:

http://developer.apple.com/mac/library/documentation/Networking/Conceptual/CFNetwork/CFNetwork.pdf

and Beej's Guide to Network programming Using Internet Sockets:

http://beej.us/guide/bgnet/

Thanks

Dave

P.S.

I am unable to use any of the 3rd party libraries and frameworks in this instance.

Answer 1

I have the following code for SSDP search in my app:

-(void)discoverDevices {
ssdpSock = [[AsyncUdpSocket alloc] initWithDelegate:self];
[ssdpSock enableBroadcast:TRUE error:nil];
NSString *str = @"M-SEARCH * HTTP/1.1\r\nHOST: 239.255.255.250:1900\r\nMan: \"ssdp:discover\"\r\nST: mydev\r\n\r\n";    
[ssdpSock bindToPort:0 error:nil];
[ssdpSock joinMulticastGroup:@"239.255.255.250" error:nil];
[ssdpSock sendData:[str dataUsingEncoding:NSUTF8StringEncoding] 
         toHost: @"239.255.255.250" port: 1900 withTimeout:-1 tag:1];
[ssdpSock receiveWithTimeout: -1 tag:1];
[NSTimer scheduledTimerWithTimeInterval: 5 target: self 
           selector:@selector(completeSearch:) userInfo: self repeats: NO]; }


-(void) completeSearch: (NSTimer *)t {
NSLog(@"%s",__FUNCTION__);
[ssdpSock close];
ssdpSock = nil;}

- (BOOL)onUdpSocket:(AsyncUdpSocket *)sock didReceiveData:(NSData *)data withTag:(long)tag fromHost:(NSString *)host port:(UInt16)port{
NSLog(@"%s %d %@ %d",__FUNCTION__,tag,host,port);
NSString *aStr = [[NSString alloc] initWithData:data encoding:NSASCIIStringEncoding];
NSLog(@"%@",aStr);}

It uses the AsyncUdpSocket from CocoaAsyncSocket.