Using system proxy in NSStream

Question

I'm using [NSStream getStreamsToHost:port:inputStream:outputStream:] to create a new stream to a web server to stream generated data on the fly. How would I go about setting up the NSStream to use the system HTTP proxy like NSURLConnection does? I can't find any info on how to lookup the system proxy, so far all I've discovered is how to setup a known SOCKS proxy against the stream.

Thanks, J

Answer 1

Disclaimer:

• I have not tried this myself, yet.
• I am a novice to using the NSStream/CF(Read|Write)StreamRef APIs.

With that out of the way, the way to go appears to be using the SystemConfiguration-framework — namely the function SCDynamicStoreCopyProxies.

This function returns a CFDictionaryRef, which can then be set as the stream's kCFStreamPropertyHTTPProxy-property (any other proxy type should work by using the protocol's equivalent key).

I don't know yet, whether it is imperative to set this property on the CoreFoundation-level or if using -[NSStream setProperty:forKey:] is possible, as well — I strongly assume the latter, but again: I more or less started seriously looking into these APIs today…

Anyway, there's a section called "Navigating Firewalls" covering this stuff in Apple's CFNetworking Programming Guide—which describes this more detailed.

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Update

In case anyone is still interested in this, there's an API which I managed to not find, the whole weekend.

On iOS, the SCDynamicStore APIs (which are referred to in the link I posted) do not exist. There is, however, another API which has been around since iOS 2.0 and is present on OS X since 10.6:

CFProxySupport

Although CFProxySupport is part of the CFNetwork framework, it isn't mentioned anywhere in the "CFNetwork Programming Guide" — which is a shame because it's simple and pleasant to use.

Filed a bug with Apple's docs (rdar://problem/10491759)