iOS - Getting CFReadStream/CFWriteStream from a socket - ios

Question

I'm trying to add some simple peer-to-peer connection functionality to an iOS library. Coding for outgoing connections was simple enough; a call to CFStreamCreatePairWithSocketToHost connects to a remote host and sets up streams for reading/writing from/to it. Simple enough.
However, I couldn't find an equivalently easy way to set up a socket to listen for/accept incoming connections. So I went back to basics and used socket(), bind(), listen(), and accept() to implement low-level connection handling, patterned largely after the example here:
http://www.pcs.cnu.edu/~dgame/sockets/server.c
That's all fine, but now that I'm able to accept incoming connections I'm wondering how to go about creating CFReadStream and CFWriteStream instances to manage them. Is there a straightforward way of doing so?
As an aside, I'm aware that a CocoaAsyncSocket library exists that supports asynchronous server sockets, but I'm really not interested in an async solution.

Answer 1

Okay, turns out that the answer was actually fairly simple. You can use:
void CFStreamCreatePairWithSocket (
CFAllocatorRef alloc,
CFSocketNativeHandle sock,
CFReadStreamRef *readStream,
CFWriteStreamRef *writeStream
);
...to bind a CFReadStream and CFWriteStream to an already connected socket. That flow seems a little backwards to me (i.e. what if bytes have already been read from the socket, etc., and why isn't it possible to just bind something to the listening/server socket such that every time a new connection is accepted corresponding CFReadStream and CFWriteStream instances are automatically set up?), but whatever.
The code goes like:
int connectedSocketId = accept(socketId, (struct sockaddr *)&clientSocket, &addrlen);
if (connectedSocketId != -1) {
//successful connection
CFReadStreamRef clientInput = NULL;
CFWriteStreamRef clientOutput = NULL;
CFStreamCreatePairWithSocket(kCFAllocatorDefault, connectedSocketId, &clientInput, &clientOutput);
if (clientInput && clientOutput) {
CFReadStreamSetProperty(clientInput, kCFStreamPropertyShouldCloseNativeSocket, kCFBooleanTrue);
CFWriteStreamSetProperty(clientOutput, kCFStreamPropertyShouldCloseNativeSocket, kCFBooleanTrue);
if (! CFReadStreamOpen(clientInput) || ! CFWriteStreamOpen(clientOutput)) {
NSLog(#"Could not initialize streams!");
}
else {
//use the streams
}
}
}
So the important things to realize were:
It's not necessary to bind anything to the socket you are listening on; instead it's possible to bind CFReadStream and CFWriteStream instances arbitrarily to any already connected socket, even if you've already read/written data from/to it.
For all its fancy verboseness, a CFSocketNativeHandle is just an int. Oh how I loathe unnecessary aliasing of primitive types to things that sound like they aren't primitive types.