Ancillary Code/QNetworkAdditions.m

/*
    File:       QNetworkAdditions.m
 
    Contains:   Works around various NSNetService problems.
 
    Written by: DTS
 
    Copyright:  Copyright (c) 2012 Apple Inc. All Rights Reserved.
 
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*/
 
#import "QNetworkAdditions.h"
 
@implementation NSNetService (QNetworkAdditions)
 
- (BOOL)qNetworkAdditions_getInputStream:(out NSInputStream **)inputStreamPtr 
    outputStream:(out NSOutputStream **)outputStreamPtr
    // The following works around three problems with -[NSNetService getInputStream:outputStream:]:
    //
    // o <rdar://problem/6868813> -- Currently the returns the streams with 
    //   +1 retain count, which is counter to Cocoa conventions and results in 
    //   leaks when you use it in ARC code.
    //
    // o <rdar://problem/9821932> -- If you create two pairs of streams from 
    //   one NSNetService and then attempt to open all the streams simultaneously, 
    //   some of the streams might fail to open.
    //
    // o <rdar://problem/9856751> -- If you create streams using 
    //   -[NSNetService getInputStream:outputStream:], start to open them, and 
    //   then release the last reference to the original NSNetService, the 
    //   streams never finish opening.  This problem is exacerbated under ARC 
    //   because ARC is better about keeping things out of the autorelease pool.
{
    BOOL                result;
    CFReadStreamRef     readStream;
    CFWriteStreamRef    writeStream;
 
    result = NO;
    
    readStream = NULL;
    writeStream = NULL;
    
    if ( (inputStreamPtr != NULL) || (outputStreamPtr != NULL) ) {
        CFNetServiceRef     netService;
 
        netService = CFNetServiceCreate(
            NULL, 
            (__bridge CFStringRef) [self domain], 
            (__bridge CFStringRef) [self type], 
            (__bridge CFStringRef) [self name], 
            0
        );
        if (netService != NULL) {
            CFStreamCreatePairWithSocketToNetService(
                NULL, 
                netService, 
                ((inputStreamPtr  != nil) ? &readStream  : NULL), 
                ((outputStreamPtr != nil) ? &writeStream : NULL)
            );
            CFRelease(netService);
        }
        
        // We have failed if the client requested an input stream and didn't 
        // get one, or requested an output stream and didn't get one.  We also 
        // fail if the client requested neither the input nor the output 
        // stream, but we don't get here in that case.
        
        result = ! ((( inputStreamPtr != NULL) && ( readStream == NULL)) || 
                    ((outputStreamPtr != NULL) && (writeStream == NULL)));
    }
    if (inputStreamPtr != NULL) {
        *inputStreamPtr  = CFBridgingRelease(readStream);
    }
    if (outputStreamPtr != NULL) {
        *outputStreamPtr = CFBridgingRelease(writeStream);
    }
    
    return result;
}
 
@end