/mio/GCDAsyncUdpSocket.m

//  
//  GCDAsyncUdpSocket
//  
//  This class is in the public domain.
//  Originally created by Robbie Hanson of Deusty LLC.
//  Updated and maintained by Deusty LLC and the Apple development community.
//  
//  https://github.com/robbiehanson/CocoaAsyncSocket
//

#if ! __has_feature(objc_arc)
#warning This file must be compiled with ARC. Use -fobjc-arc flag (or convert project to ARC).
// For more information see: https://github.com/robbiehanson/CocoaAsyncSocket/wiki/ARC
#endif

/**
 * Does ARC support support GCD objects?
 * It does if the minimum deployment target is iOS 6+ or Mac OS X 8+
**/
#if TARGET_OS_IPHONE

  // Compiling for iOS

  #if __IPHONE_OS_VERSION_MIN_REQUIRED >= 60000 // iOS 6.0 or later
    #define NEEDS_DISPATCH_RETAIN_RELEASE 0
  #else                                         // iOS 5.X or earlier
    #define NEEDS_DISPATCH_RETAIN_RELEASE 1
  #endif

#else

  // Compiling for Mac OS X

  #if MAC_OS_X_VERSION_MIN_REQUIRED >= 1080     // Mac OS X 10.8 or later
    #define NEEDS_DISPATCH_RETAIN_RELEASE 0
  #else
    #define NEEDS_DISPATCH_RETAIN_RELEASE 1     // Mac OS X 10.7 or earlier
  #endif

#endif

#import "GCDAsyncUdpSocket.h"

#if TARGET_OS_IPHONE
  #import <CFNetwork/CFNetwork.h>
  #import <UIKit/UIKit.h>
#endif

#import <arpa/inet.h>
#import <fcntl.h>
#import <ifaddrs.h>
#import <netdb.h>
#import <net/if.h>
#import <sys/socket.h>
#import <sys/types.h>


#if 0

// Logging Enabled - See log level below

// Logging uses the CocoaLumberjack framework (which is also GCD based).
// http://code.google.com/p/cocoalumberjack/
// 
// It allows us to do a lot of logging without significantly slowing down the code.
#import "DDLog.h"

#define LogAsync   NO
#define LogContext 65535

#define LogObjc(flg, frmt, ...) LOG_OBJC_MAYBE(LogAsync, logLevel, flg, LogContext, frmt, ##__VA_ARGS__)
#define LogC(flg, frmt, ...)    LOG_C_MAYBE(LogAsync, logLevel, flg, LogContext, frmt, ##__VA_ARGS__)

#define LogError(frmt, ...)     LogObjc(LOG_FLAG_ERROR,   (@"%@: " frmt), THIS_FILE, ##__VA_ARGS__)
#define LogWarn(frmt, ...)      LogObjc(LOG_FLAG_WARN,    (@"%@: " frmt), THIS_FILE, ##__VA_ARGS__)
#define LogInfo(frmt, ...)      LogObjc(LOG_FLAG_INFO,    (@"%@: " frmt), THIS_FILE, ##__VA_ARGS__)
#define LogVerbose(frmt, ...)   LogObjc(LOG_FLAG_VERBOSE, (@"%@: " frmt), THIS_FILE, ##__VA_ARGS__)

#define LogCError(frmt, ...)    LogC(LOG_FLAG_ERROR,   (@"%@: " frmt), THIS_FILE, ##__VA_ARGS__)
#define LogCWarn(frmt, ...)     LogC(LOG_FLAG_WARN,    (@"%@: " frmt), THIS_FILE, ##__VA_ARGS__)
#define LogCInfo(frmt, ...)     LogC(LOG_FLAG_INFO,    (@"%@: " frmt), THIS_FILE, ##__VA_ARGS__)
#define LogCVerbose(frmt, ...)  LogC(LOG_FLAG_VERBOSE, (@"%@: " frmt), THIS_FILE, ##__VA_ARGS__)

#define LogTrace()              LogObjc(LOG_FLAG_VERBOSE, @"%@: %@", THIS_FILE, THIS_METHOD)
#define LogCTrace()             LogC(LOG_FLAG_VERBOSE, @"%@: %s", THIS_FILE, __FUNCTION__)

// Log levels : off, error, warn, info, verbose
static const int logLevel = LOG_LEVEL_VERBOSE;

#else

// Logging Disabled

#define LogError(frmt, ...)     {}
#define LogWarn(frmt, ...)      {}
#define LogInfo(frmt, ...)      {}
#define LogVerbose(frmt, ...)   {}

#define LogCError(frmt, ...)    {}
#define LogCWarn(frmt, ...)     {}
#define LogCInfo(frmt, ...)     {}
#define LogCVerbose(frmt, ...)  {}

#define LogTrace()              {}
#define LogCTrace(frmt, ...)    {}

#endif

/**
 * Seeing a return statements within an inner block
 * can sometimes be mistaken for a return point of the enclosing method.
 * This makes inline blocks a bit easier to read.
**/
#define return_from_block  return

/**
 * A socket file descriptor is really just an integer.
 * It represents the index of the socket within the kernel.
 * This makes invalid file descriptor comparisons easier to read.
**/
#define SOCKET_NULL -1

/**
 * Just to type less code.
**/
#define AutoreleasedBlock(block) ^{ @autoreleasepool { block(); }} 


@class GCDAsyncUdpSendPacket;

NSString *const GCDAsyncUdpSocketException = @"GCDAsyncUdpSocketException";
NSString *const GCDAsyncUdpSocketErrorDomain = @"GCDAsyncUdpSocketErrorDomain";

NSString *const GCDAsyncUdpSocketQueueName = @"GCDAsyncUdpSocket";
NSString *const GCDAsyncUdpSocketThreadName = @"GCDAsyncUdpSocket-CFStream";

enum GCDAsyncUdpSocketFlags
{
	kDidCreateSockets        = 1 <<  0,  // If set, the sockets have been created.
	kDidBind                 = 1 <<  1,  // If set, bind has been called.
	kConnecting              = 1 <<  2,  // If set, a connection attempt is in progress.
	kDidConnect              = 1 <<  3,  // If set, socket is connected.
	kReceiveOnce             = 1 <<  4,  // If set, one-at-a-time receive is enabled
	kReceiveContinuous       = 1 <<  5,  // If set, continuous receive is enabled
	kIPv4Deactivated         = 1 <<  6,  // If set, socket4 was closed due to bind or connect on IPv6.
	kIPv6Deactivated         = 1 <<  7,  // If set, socket6 was closed due to bind or connect on IPv4.
	kSend4SourceSuspended    = 1 <<  8,  // If set, send4Source is suspended.
	kSend6SourceSuspended    = 1 <<  9,  // If set, send6Source is suspended.
	kReceive4SourceSuspended = 1 << 10,  // If set, receive4Source is suspended.
	kReceive6SourceSuspended = 1 << 11,  // If set, receive6Source is suspended.
	kSock4CanAcceptBytes     = 1 << 12,  // If set, we know socket4 can accept bytes. If unset, it's unknown.
	kSock6CanAcceptBytes     = 1 << 13,  // If set, we know socket6 can accept bytes. If unset, it's unknown.
	kForbidSendReceive       = 1 << 14,  // If set, no new send or receive operations are allowed to be queued.
	kCloseAfterSends         = 1 << 15,  // If set, close as soon as no more sends are queued.
	kFlipFlop                = 1 << 16,  // Used to alternate between IPv4 and IPv6 sockets.
#if TARGET_OS_IPHONE
	kAddedStreamListener     = 1 << 17,  // If set, CFStreams have been added to listener thread
#endif
};

enum GCDAsyncUdpSocketConfig
{
	kIPv4Disabled  = 1 << 0,  // If set, IPv4 is disabled
	kIPv6Disabled  = 1 << 1,  // If set, IPv6 is disabled
	kPreferIPv4    = 1 << 2,  // If set, IPv4 is preferred over IPv6
	kPreferIPv6    = 1 << 3,  // If set, IPv6 is preferred over IPv4
};

////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
#pragma mark -
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////

@interface GCDAsyncUdpSocket ()
{
	id delegate;
	dispatch_queue_t delegateQueue;
	
	GCDAsyncUdpSocketReceiveFilterBlock receiveFilterBlock;
	dispatch_queue_t receiveFilterQueue;
	BOOL receiveFilterAsync;
	
	GCDAsyncUdpSocketSendFilterBlock sendFilterBlock;
	dispatch_queue_t sendFilterQueue;
	BOOL sendFilterAsync;
	
	uint32_t flags;
	uint16_t config;
	
	uint16_t max4ReceiveSize;
	uint32_t max6ReceiveSize;
	
	int socket4FD;
	int socket6FD;
	
	dispatch_queue_t socketQueue;
	
	dispatch_source_t send4Source;
	dispatch_source_t send6Source;
	dispatch_source_t receive4Source;
	dispatch_source_t receive6Source;
	dispatch_source_t sendTimer;
	
	GCDAsyncUdpSendPacket *currentSend;
	NSMutableArray *sendQueue;
	
	unsigned long socket4FDBytesAvailable;
	unsigned long socket6FDBytesAvailable;
	
	uint32_t pendingFilterOperations;
	
	NSData   *cachedLocalAddress4;
	NSString *cachedLocalHost4;
	uint16_t  cachedLocalPort4;
	
	NSData   *cachedLocalAddress6;
	NSString *cachedLocalHost6;
	uint16_t  cachedLocalPort6;
	
	NSData   *cachedConnectedAddress;
	NSString *cachedConnectedHost;
	uint16_t  cachedConnectedPort;
	int       cachedConnectedFamily;
	
#if TARGET_OS_IPHONE
	CFStreamClientContext streamContext;
	CFReadStreamRef readStream4;
	CFReadStreamRef readStream6;
	CFWriteStreamRef writeStream4;
	CFWriteStreamRef writeStream6;
#endif
	
	id userData;
}

- (void)resumeSend4Source;
- (void)resumeSend6Source;
- (void)resumeReceive4Source;
- (void)resumeReceive6Source;
- (void)closeSockets;

- (void)maybeConnect;
- (BOOL)connectWithAddress4:(NSData *)address4 error:(NSError **)errPtr;
- (BOOL)connectWithAddress6:(NSData *)address6 error:(NSError **)errPtr;

- (void)maybeDequeueSend;
- (void)doPreSend;
- (void)doSend;
- (void)endCurrentSend;
- (void)setupSendTimerWithTimeout:(NSTimeInterval)timeout;

- (void)doReceive;
- (void)doReceiveEOF;

- (void)closeWithError:(NSError *)error;

- (BOOL)performMulticastRequest:(int)requestType forGroup:(NSString *)group onInterface:(NSString *)interface error:(NSError **)errPtr;

#if TARGET_OS_IPHONE
- (BOOL)createReadAndWriteStreams:(NSError **)errPtr;
- (BOOL)registerForStreamCallbacks:(NSError **)errPtr;
- (BOOL)addStreamsToRunLoop:(NSError **)errPtr;
- (BOOL)openStreams:(NSError **)errPtr;
- (void)removeStreamsFromRunLoop;
- (void)closeReadAndWriteStreams;
#endif

+ (NSString *)hostFromSockaddr4:(const struct sockaddr_in *)pSockaddr4;
+ (NSString *)hostFromSockaddr6:(const struct sockaddr_in6 *)pSockaddr6;
+ (uint16_t)portFromSockaddr4:(const struct sockaddr_in *)pSockaddr4;
+ (uint16_t)portFromSockaddr6:(const struct sockaddr_in6 *)pSockaddr6;

#if TARGET_OS_IPHONE
// Forward declaration
+ (void)listenerThread;
#endif

@end

////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
#pragma mark -
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////

/**
 * The GCDAsyncUdpSendPacket encompasses the instructions for a single send/write.
**/
@interface GCDAsyncUdpSendPacket : NSObject {
@public
	NSData *buffer;
	NSTimeInterval timeout;
	long tag;
	
	BOOL resolveInProgress;
	BOOL filterInProgress;
	
	NSArray *resolvedAddresses;
	NSError *resolveError;
	
	NSData *address;
	int addressFamily;
}

- (id)initWithData:(NSData *)d timeout:(NSTimeInterval)t tag:(long)i;

@end

@implementation GCDAsyncUdpSendPacket

- (id)initWithData:(NSData *)d timeout:(NSTimeInterval)t tag:(long)i
{
	if ((self = [super init]))
	{
		buffer = d;
		timeout = t;
		tag = i;
		
		resolveInProgress = NO;
	}
	return self;
}


@end

////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
#pragma mark -
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////

@interface GCDAsyncUdpSpecialPacket : NSObject {
@public
//	uint8_t type;
	
	BOOL resolveInProgress;
	
	NSArray *addresses;
	NSError *error;
}

- (id)init;

@end

@implementation GCDAsyncUdpSpecialPacket

- (id)init
{
	self = [super init];
	return self;
}


@end

////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
#pragma mark -
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////

@implementation GCDAsyncUdpSocket

- (id)init
{
	LogTrace();
	
	return [self initWithDelegate:nil delegateQueue:NULL socketQueue:NULL];
}

- (id)initWithSocketQueue:(dispatch_queue_t)sq
{
	LogTrace();
	
	return [self initWithDelegate:nil delegateQueue:NULL socketQueue:sq];
}

- (id)initWithDelegate:(id)aDelegate delegateQueue:(dispatch_queue_t)dq
{
	LogTrace();
	
	return [self initWithDelegate:aDelegate delegateQueue:dq socketQueue:NULL];
}

- (id)initWithDelegate:(id)aDelegate delegateQueue:(dispatch_queue_t)dq socketQueue:(dispatch_queue_t)sq
{
	LogTrace();
	
	if ((self = [super init]))
	{
		delegate = aDelegate;
		
		if (dq)
		{
			delegateQueue = dq;
			#if NEEDS_DISPATCH_RETAIN_RELEASE
			dispatch_retain(delegateQueue);
			#endif
		}
		
		max4ReceiveSize = 9216;
		max6ReceiveSize = 9216;
		
		socket4FD = SOCKET_NULL;
		socket6FD = SOCKET_NULL;
		
		if (sq)
		{
			NSAssert(sq != dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_LOW, 0),
			         @"The given socketQueue parameter must not be a concurrent queue.");
			NSAssert(sq != dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_HIGH, 0),
			         @"The given socketQueue parameter must not be a concurrent queue.");
			NSAssert(sq != dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0),
			         @"The given socketQueue parameter must not be a concurrent queue.");
			
			socketQueue = sq;
			#if NEEDS_DISPATCH_RETAIN_RELEASE
			dispatch_retain(socketQueue);
			#endif
		}
		else
		{
			socketQueue = dispatch_queue_create([GCDAsyncUdpSocketQueueName UTF8String], NULL);
		}
		
		currentSend = nil;
		sendQueue = [[NSMutableArray alloc] initWithCapacity:5];
		
		#if TARGET_OS_IPHONE
		[[NSNotificationCenter defaultCenter] addObserver:self
		                                         selector:@selector(applicationWillEnterForeground:)
		                                             name:UIApplicationWillEnterForegroundNotification
		                                           object:nil];
		#endif
	}
	return self;
}

- (void)dealloc
{
	LogInfo(@"%@ - %@ (start)", THIS_METHOD, self);
	
#if TARGET_OS_IPHONE
	[[NSNotificationCenter defaultCenter] removeObserver:self];
#endif
	
	if (dispatch_get_current_queue() == socketQueue)
	{
		[self closeWithError:nil];
	}
	else
	{
		dispatch_sync(socketQueue, ^{
			[self closeWithError:nil];
		});
	}
	
	delegate = nil;
	#if NEEDS_DISPATCH_RETAIN_RELEASE
	if (delegateQueue) dispatch_release(delegateQueue);
	#endif
	delegateQueue = NULL;
	
	#if NEEDS_DISPATCH_RETAIN_RELEASE
	if (socketQueue) dispatch_release(socketQueue);
	#endif
	socketQueue = NULL;
	
	LogInfo(@"%@ - %@ (finish)", THIS_METHOD, self);
}

////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
#pragma mark Configuration
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////

- (id)delegate
{
	if (dispatch_get_current_queue() == socketQueue)
	{
		return delegate;
	}
	else
	{
		__block id result = nil;
		
		dispatch_sync(socketQueue, ^{
			result = delegate;
		});
		
		return result;
	}
}

- (void)setDelegate:(id)newDelegate synchronously:(BOOL)synchronously
{
	dispatch_block_t block = ^{
		delegate = newDelegate;
	};
	
	if (dispatch_get_current_queue() == socketQueue) {
		block();
	}
	else {
		if (synchronously)
			dispatch_sync(socketQueue, block);
		else
			dispatch_async(socketQueue, block);
	}
}

- (void)setDelegate:(id)newDelegate
{
	[self setDelegate:newDelegate synchronously:NO];
}

- (void)synchronouslySetDelegate:(id)newDelegate
{
	[self setDelegate:newDelegate synchronously:YES];
}

- (dispatch_queue_t)delegateQueue
{
	if (dispatch_get_current_queue() == socketQueue)
	{
		return delegateQueue;
	}
	else
	{
		__block dispatch_queue_t result = NULL;
		
		dispatch_sync(socketQueue, ^{
			result = delegateQueue;
		});
		
		return result;
	}
}

- (void)setDelegateQueue:(dispatch_queue_t)newDelegateQueue synchronously:(BOOL)synchronously
{
	dispatch_block_t block = ^{
		
		#if NEEDS_DISPATCH_RETAIN_RELEASE
		if (delegateQueue) dispatch_release(delegateQueue);
		if (newDelegateQueue) dispatch_retain(newDelegateQueue);
		#endif
		
		delegateQueue = newDelegateQueue;
	};
	
	if (dispatch_get_current_queue() == socketQueue) {
		block();
	}
	else {
		if (synchronously)
			dispatch_sync(socketQueue, block);
		else
			dispatch_async(socketQueue, block);
	}
}

- (void)setDelegateQueue:(dispatch_queue_t)newDelegateQueue
{
	[self setDelegateQueue:newDelegateQueue synchronously:NO];
}

- (void)synchronouslySetDelegateQueue:(dispatch_queue_t)newDelegateQueue
{
	[self setDelegateQueue:newDelegateQueue synchronously:YES];
}

- (void)getDelegate:(id *)delegatePtr delegateQueue:(dispatch_queue_t *)delegateQueuePtr
{
	if (dispatch_get_current_queue() == socketQueue)
	{
		if (delegatePtr) *delegatePtr = delegate;
		if (delegateQueuePtr) *delegateQueuePtr = delegateQueue;
	}
	else
	{
		__block id dPtr = NULL;
		__block dispatch_queue_t dqPtr = NULL;
		
		dispatch_sync(socketQueue, ^{
			dPtr = delegate;
			dqPtr = delegateQueue;
		});
		
		if (delegatePtr) *delegatePtr = dPtr;
		if (delegateQueuePtr) *delegateQueuePtr = dqPtr;
	}
}

- (void)setDelegate:(id)newDelegate delegateQueue:(dispatch_queue_t)newDelegateQueue synchronously:(BOOL)synchronously
{
	dispatch_block_t block = ^{
		
		delegate = newDelegate;
		
		#if NEEDS_DISPATCH_RETAIN_RELEASE
		if (delegateQueue) dispatch_release(delegateQueue);
		if (newDelegateQueue) dispatch_retain(newDelegateQueue);
		#endif
		
		delegateQueue = newDelegateQueue;
	};
	
	if (dispatch_get_current_queue() == socketQueue) {
		block();
	}
	else {
		if (synchronously)
			dispatch_sync(socketQueue, block);
		else
			dispatch_async(socketQueue, block);
	}
}

- (void)setDelegate:(id)newDelegate delegateQueue:(dispatch_queue_t)newDelegateQueue
{
	[self setDelegate:newDelegate delegateQueue:newDelegateQueue synchronously:NO];
}

- (void)synchronouslySetDelegate:(id)newDelegate delegateQueue:(dispatch_queue_t)newDelegateQueue
{
	[self setDelegate:newDelegate delegateQueue:newDelegateQueue synchronously:YES];
}

- (BOOL)isIPv4Enabled
{
	// Note: YES means kIPv4Disabled is OFF
	
	__block BOOL result = NO;
	
	dispatch_block_t block = ^{
		
		result = ((config & kIPv4Disabled) == 0);
	};
	
	if (dispatch_get_current_queue() == socketQueue)
		block();
	else
		dispatch_sync(socketQueue, block);
	
	return result;
}

- (void)setIPv4Enabled:(BOOL)flag
{
	// Note: YES means kIPv4Disabled is OFF
	
	dispatch_block_t block = ^{
		
		LogVerbose(@"%@ %@", THIS_METHOD, (flag ? @"YES" : @"NO"));
		
		if (flag)
			config &= ~kIPv4Disabled;
		else
			config |= kIPv4Disabled;
	};
	
	if (dispatch_get_current_queue() == socketQueue)
		block();
	else
		dispatch_async(socketQueue, block);
}

- (BOOL)isIPv6Enabled
{
	// Note: YES means kIPv6Disabled is OFF
	
	__block BOOL result = NO;
	
	dispatch_block_t block = ^{
		
		result = ((config & kIPv6Disabled) == 0);
	};
	
	if (dispatch_get_current_queue() == socketQueue)
		block();
	else
		dispatch_sync(socketQueue, block);
	
	return result;
}

- (void)setIPv6Enabled:(BOOL)flag
{
	// Note: YES means kIPv6Disabled is OFF
	
	dispatch_block_t block = ^{
		
		LogVerbose(@"%@ %@", THIS_METHOD, (flag ? @"YES" : @"NO"));
		
		if (flag)
			config &= ~kIPv6Disabled;
		else
			config |= kIPv6Disabled;
	};
	
	if (dispatch_get_current_queue() == socketQueue)
		block();
	else
		dispatch_async(socketQueue, block);
}

- (BOOL)isIPv4Preferred
{
	__block BOOL result = NO;
	
	dispatch_block_t block = ^{
		result = (config & kPreferIPv4) ? YES : NO;
	};
	
	if (dispatch_get_current_queue() == socketQueue)
		block();
	else
		dispatch_sync(socketQueue, block);
	
	return result;
}

- (BOOL)isIPv6Preferred
{
	__block BOOL result = NO;
	
	dispatch_block_t block = ^{
		result = (config & kPreferIPv6) ? YES : NO;
	};
	
	if (dispatch_get_current_queue() == socketQueue)
		block();
	else
		dispatch_sync(socketQueue, block);
	
	return result;
}

- (BOOL)isIPVersionNeutral
{
	__block BOOL result = NO;
	
	dispatch_block_t block = ^{
		result = (config & (kPreferIPv4 | kPreferIPv6)) == 0;
	};
	
	if (dispatch_get_current_queue() == socketQueue)
		block();
	else
		dispatch_sync(socketQueue, block);
	
	return result;
}

- (void)setPreferIPv4
{
	dispatch_block_t block = ^{
		
		LogTrace();
		
		config |=  kPreferIPv4;
		config &= ~kPreferIPv6;
		
	};
	
	if (dispatch_get_current_queue() == socketQueue)
		block();
	else
		dispatch_async(socketQueue, block);
}

- (void)setPreferIPv6
{
	dispatch_block_t block = ^{
		
		LogTrace();
		
		config &= ~kPreferIPv4;
		config |=  kPreferIPv6;
		
	};
	
	if (dispatch_get_current_queue() == socketQueue)
		block();
	else
		dispatch_async(socketQueue, block);
}

- (void)setIPVersionNeutral
{
	dispatch_block_t block = ^{
		
		LogTrace();
		
		config &= ~kPreferIPv4;
		config &= ~kPreferIPv6;
		
	};
	
	if (dispatch_get_current_queue() == socketQueue)
		block();
	else
		dispatch_async(socketQueue, block);
}

- (uint16_t)maxReceiveIPv4BufferSize
{
	__block uint16_t result = 0;
	
	dispatch_block_t block = ^{
		
		result = max4ReceiveSize;
	};
	
	if (dispatch_get_current_queue() == socketQueue)
		block();
	else
		dispatch_sync(socketQueue, block);
	
	return result;
}

- (void)setMaxReceiveIPv4BufferSize:(uint16_t)max
{
	dispatch_block_t block = ^{
		
		LogVerbose(@"%@ %u", THIS_METHOD, (unsigned)max);
		
		max4ReceiveSize = max;
	};
	
	if (dispatch_get_current_queue() == socketQueue)
		block();
	else
		dispatch_async(socketQueue, block);
}

- (uint32_t)maxReceiveIPv6BufferSize
{
	__block uint32_t result = 0;
	
	dispatch_block_t block = ^{
		
		result = max6ReceiveSize;
	};
	
	if (dispatch_get_current_queue() == socketQueue)
		block();
	else
		dispatch_sync(socketQueue, block);
	
	return result;
}

- (void)setMaxReceiveIPv6BufferSize:(uint32_t)max
{
	dispatch_block_t block = ^{
		
		LogVerbose(@"%@ %u", THIS_METHOD, (unsigned)max);
		
		max6ReceiveSize = max;
	};
	
	if (dispatch_get_current_queue() == socketQueue)
		block();
	else
		dispatch_async(socketQueue, block);
}


- (id)userData
{
	__block id result = nil;
	
	dispatch_block_t block = ^{
		
		result = userData;
	};
	
	if (dispatch_get_current_queue() == socketQueue)
		block();
	else
		dispatch_sync(socketQueue, block);
	
	return result;
}

- (void)setUserData:(id)arbitraryUserData
{
	dispatch_block_t block = ^{
		
		if (userData != arbitraryUserData)
		{
			userData = arbitraryUserData;
		}
	};
	
	if (dispatch_get_current_queue() == socketQueue)
		block();
	else
		dispatch_async(socketQueue, block);
}

////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
#pragma mark Delegate Helpers
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////

- (void)notifyDidConnectToAddress:(NSData *)anAddress
{
	LogTrace();
	
	if (delegateQueue && [delegate respondsToSelector:@selector(udpSocket:didConnectToAddress:)])
	{
		id theDelegate = delegate;
		NSData *address = [anAddress copy]; // In case param is NSMutableData
		
		dispatch_async(delegateQueue, ^{ @autoreleasepool {
			
			[theDelegate udpSocket:self didConnectToAddress:address];
		}});
	}
}

- (void)notifyDidNotConnect:(NSError *)error
{
	LogTrace();
	
	if (delegateQueue && [delegate respondsToSelector:@selector(udpSocket:didNotConnect:)])
	{
		id theDelegate = delegate;
		
		dispatch_async(delegateQueue, ^{ @autoreleasepool {
			
			[theDelegate udpSocket:self didNotConnect:error];
		}});
	}
}

- (void)notifyDidSendDataWithTag:(long)tag
{
	LogTrace();
	
	if (delegateQueue && [delegate respondsToSelector:@selector(udpSocket:didSendDataWithTag:)])
	{
		id theDelegate = delegate;
		
		dispatch_async(delegateQueue, ^{ @autoreleasepool {
			
			[theDelegate udpSocket:self didSendDataWithTag:tag];
		}});
	}
}

- (void)notifyDidNotSendDataWithTag:(long)tag dueToError:(NSError *)error
{
	LogTrace();
	
	if (delegateQueue && [delegate respondsToSelector:@selector(udpSocket:didNotSendDataWithTag:dueToError:)])
	{
		id theDelegate = delegate;
		
		dispatch_async(delegateQueue, ^{ @autoreleasepool {
			
			[theDelegate udpSocket:self didNotSendDataWithTag:tag dueToError:error];
		}});
	}
}

- (void)notifyDidReceiveData:(NSData *)data fromAddress:(NSData *)address withFilterContext:(id)context
{
	LogTrace();
	
	SEL selector = @selector(udpSocket:didReceiveData:fromAddress:withFilterContext:);
	
	if (delegateQueue && [delegate respondsToSelector:selector])
	{
		id theDelegate = delegate;
		
		dispatch_async(delegateQueue, ^{ @autoreleasepool {
			
			[theDelegate udpSocket:self didReceiveData:data fromAddress:address withFilterContext:context];
		}});
	}
}

- (void)notifyDidCloseWithError:(NSError *)error
{
	LogTrace();
	
	if (delegateQueue && [delegate respondsToSelector:@selector(udpSocketDidClose:withError:)])
	{
		id theDelegate = delegate;
		
		dispatch_async(delegateQueue, ^{ @autoreleasepool {
			
			[theDelegate udpSocketDidClose:self withError:error];
		}});
	}
}

////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
#pragma mark Errors
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////

- (NSError *)badConfigError:(NSString *)errMsg
{
	NSDictionary *userInfo = [NSDictionary dictionaryWithObject:errMsg forKey:NSLocalizedDescriptionKey];
	
	return [NSError errorWithDomain:GCDAsyncUdpSocketErrorDomain
	                           code:GCDAsyncUdpSocketBadConfigError
	                       userInfo:userInfo];
}

- (NSError *)badParamError:(NSString *)errMsg
{
	NSDictionary *userInfo = [NSDictionary dictionaryWithObject:errMsg forKey:NSLocalizedDescriptionKey];
	
	return [NSError errorWithDomain:GCDAsyncUdpSocketErrorDomain
	                           code:GCDAsyncUdpSocketBadParamError
	                       userInfo:userInfo];
}

- (NSError *)gaiError:(int)gai_error
{
	NSString *errMsg = [NSString stringWithCString:gai_strerror(gai_error) encoding:NSASCIIStringEncoding];
	NSDictionary *userInfo = [NSDictionary dictionaryWithObject:errMsg forKey:NSLocalizedDescriptionKey];
	
	return [NSError errorWithDomain:@"kCFStreamErrorDomainNetDB" code:gai_error userInfo:userInfo];
}

- (NSError *)errnoErrorWithReason:(NSString *)reason
{
	NSString *errMsg = [NSString stringWithUTF8String:strerror(errno)];
	NSDictionary *userInfo;
	
	if (reason)
		userInfo = [NSDictionary dictionaryWithObjectsAndKeys:errMsg, NSLocalizedDescriptionKey,
		                                                      reason, NSLocalizedFailureReasonErrorKey, nil];
	else
		userInfo = [NSDictionary dictionaryWithObjectsAndKeys:errMsg, NSLocalizedDescriptionKey, nil];
	
	return [NSError errorWithDomain:NSPOSIXErrorDomain code:errno userInfo:userInfo];
}

- (NSError *)errnoError
{
	return [self errnoErrorWithReason:nil];
}

/**
 * Returns a standard send timeout error.
**/
- (NSError *)sendTimeoutError
{
	NSString *errMsg = NSLocalizedStringWithDefaultValue(@"GCDAsyncUdpSocketSendTimeoutError",
	                                                     @"GCDAsyncUdpSocket", [NSBundle mainBundle],
	                                                     @"Send operation timed out", nil);
	
	NSDictionary *userInfo = [NSDictionary dictionaryWithObject:errMsg forKey:NSLocalizedDescriptionKey];
	
	return [NSError errorWithDomain:GCDAsyncUdpSocketErrorDomain
	                           code:GCDAsyncUdpSocketSendTimeoutError
	                       userInfo:userInfo];
}

- (NSError *)socketClosedError
{
	NSString *errMsg = NSLocalizedStringWithDefaultValue(@"GCDAsyncUdpSocketClosedError",
	                                                     @"GCDAsyncUdpSocket", [NSBundle mainBundle],
	                                                     @"Socket closed", nil);
	
	NSDictionary *userInfo = [NSDictionary dictionaryWithObject:errMsg forKey:NSLocalizedDescriptionKey];
	
	return [NSError errorWithDomain:GCDAsyncUdpSocketErrorDomain code:GCDAsyncUdpSocketClosedError userInfo:userInfo];
}

- (NSError *)otherError:(NSString *)errMsg
{
	NSDictionary *userInfo = [NSDictionary dictionaryWithObject:errMsg forKey:NSLocalizedDescriptionKey];
	
	return [NSError errorWithDomain:GCDAsyncUdpSocketErrorDomain
	                           code:GCDAsyncUdpSocketOtherError
	                       userInfo:userInfo];
}

////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
#pragma mark Utilities
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////

- (BOOL)preOp:(NSError **)errPtr
{
	NSAssert(dispatch_get_current_queue() == socketQueue, @"Must be dispatched on socketQueue");
	
	if (delegate == nil) // Must have delegate set
	{
		if (errPtr)
		{
			NSString *msg = @"Attempting to use socket without a delegate. Set a delegate first.";
			*errPtr = [self badConfigError:msg];
		}
		return NO;
	}
	
	if (delegateQueue == NULL) // Must have delegate queue set
	{
		if (errPtr)
		{
			NSString *msg = @"Attempting to use socket without a delegate queue. Set a delegate queue first.";
			*errPtr = [self badConfigError:msg];
		}
		return NO;
	}
	
	return YES;
}

/**
 * This method executes on a global concurrent queue.
 * When complete, it executes the given completion block on the socketQueue.
**/
- (void)asyncResolveHost:(NSString *)aHost
                    port:(uint16_t)port
     withCompletionBlock:(void (^)(NSArray *addresses, NSError *error))completionBlock
{
	LogTrace();
	
	// Check parameter(s)
	
	if (aHost == nil)
	{
		NSString *msg = @"The host param is nil. Should be domain name or IP address string.";
		NSError *error = [self badParamError:msg];
		
		// We should still use dispatch_async since this method is expected to be asynchronous
		
		dispatch_async(socketQueue, ^{ @autoreleasepool {
			
			completionBlock(nil, error);
		}});
		
		return;
	}
	
	// It's possible that the given aHost parameter is actually a NSMutableString.
	// So we want to copy it now, within this block that will be executed synchronously.
	// This way the asynchronous lookup block below doesn't have to worry about it changing.
	
	NSString *host = [aHost copy];
	
	
	dispatch_queue_t globalConcurrentQueue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);
	dispatch_async(globalConcurrentQueue, ^{ @autoreleasepool {
		
		NSMutableArray *addresses = [NSMutableArray arrayWithCapacity:2];
		NSError *error = nil;
		
		if ([host isEqualToString:@"localhost"] || [host isEqualToString:@"loopback"])
		{
			// Use LOOPBACK address
			struct sockaddr_in sockaddr4;
			memset(&sockaddr4, 0, sizeof(sockaddr4));
			
			sockaddr4.sin_len         = sizeof(struct sockaddr_in);
			sockaddr4.sin_family      = AF_INET;
			sockaddr4.sin_port        = htons(port);
			sockaddr4.sin_addr.s_addr = htonl(INADDR_LOOPBACK);
			
			struct sockaddr_in6 sockaddr6;
			memset(&sockaddr6, 0, sizeof(sockaddr6));
			
			sockaddr6.sin6_len       = sizeof(struct sockaddr_in6);
			sockaddr6.sin6_family    = AF_INET6;
			sockaddr6.sin6_port      = htons(port);
			sockaddr6.sin6_addr      = in6addr_loopback;
			
			// Wrap the native address structures and add to list
			[addresses addObject:[NSData dataWithBytes:&sockaddr4 length:sizeof(sockaddr4)]];
			[addresses addObject:[NSData dataWithBytes:&sockaddr6 length:sizeof(sockaddr6)]];
		}
		else
		{
			NSString *portStr = [NSString stringWithFormat:@"%hu", port];
			
			struct addrinfo hints, *res, *res0;
			
			memset(&hints, 0, sizeof(hints));
			hints.ai_family   = PF_UNSPEC;
			hints.ai_socktype = SOCK_DGRAM;
			hints.ai_protocol = IPPROTO_UDP;
			
			int gai_error = getaddrinfo([host UTF8String], [portStr UTF8String], &hints, &res0);
			
			if (gai_error)
			{
				error = [self gaiError:gai_error];
			}
			else
			{
				for(res = res0; res; res = res->ai_next)
				{
					if (res->ai_family == AF_INET)
					{
						// Found IPv4 address
						// Wrap the native address structure and add to list
						
						[addresses addObject:[NSData dataWithBytes:res->ai_addr length:res->ai_addrlen]];
					}
					else if (res->ai_family == AF_INET6)
					{
						// Found IPv6 address
						// Wrap the native address structure and add to list
						
						[addresses addObject:[NSData dataWithBytes:res->ai_addr length:res->ai_addrlen]];
					}
				}
				freeaddrinfo(res0);
				
				if ([addresses count] == 0)
				{
					error = [self gaiError:EAI_FAIL];
				}
			}
		}
		
		dispatch_async(socketQueue, ^{ @autoreleasepool {
			
			completionBlock(addresses, error);
		}});
		
	}});
}

/**
 * This method picks an address from the given list of addresses.
 * The address picked depends upon which protocols are disabled, deactived, & preferred.
 * 
 * Returns the address family (AF_INET or AF_INET6) of the picked address,
 * or AF_UNSPEC and the corresponding error is there's a problem.
**/
- (int)getAddress:(NSData **)addressPtr error:(NSError **)errorPtr fromAddresses:(NSArray *)addresses
{
	NSAssert(dispatch_get_current_queue() == socketQueue, @"Must be dispatched on socketQueue");
	NSAssert([addresses count] > 0, @"Expected at least one address");
	
	int resultAF = AF_UNSPEC;
	NSData *resultAddress = nil;
	NSError *resultError = nil;
	
	// Check for problems
	
	BOOL resolvedIPv4Address = NO;
	BOOL resolvedIPv6Address = NO;
	
	for (NSData *address in addresses)
	{
		switch ([[self class] familyFromAddress:address])
		{
			case AF_INET  : resolvedIPv4Address = YES; break;
			case AF_INET6 : resolvedIPv6Address = YES; break;
			
			default       : NSAssert(NO, @"Addresses array contains invalid address");
		}
	}
	
	BOOL isIPv4Disabled = (config & kIPv4Disabled) ? YES : NO;
	BOOL isIPv6Disabled = (config & kIPv6Disabled) ? YES : NO;
	
	if (isIPv4Disabled && !resolvedIPv6Address)
	{
		NSString *msg = @"IPv4 has been disabled and DNS lookup found no IPv6 address(es).";
		resultError = [self otherError:msg];
		
		if (addressPtr) *addressPtr = resultAddress;
		if (errorPtr) *errorPtr = resultError;
		
		return resultAF;
	}
	
	if (isIPv6Disabled && !resolvedIPv4Address)
	{
		NSString *msg = @"IPv6 has been disabled and DNS lookup found no IPv4 address(es).";
		resultError = [self otherError:msg];
		
		if (addressPtr) *addressPtr = resultAddress;
		if (errorPtr) *errorPtr = resultError;
		
		return resultAF;
	}
	
	BOOL isIPv4Deactivated = (flags & kIPv4Deactivated) ? YES : NO;
	BOOL isIPv6Deactivated = (flags & kIPv6Deactivated) ? YES : NO;
	
	if (isIPv4Deactivated && !resolvedIPv6Address)
	{
		NSString *msg = @"IPv4 has been deactivated due to bind/connect, and DNS lookup found no IPv6 address(es).";
		resultError = [self otherError:msg];
		
		if (addressPtr) *addressPtr = resultAddress;
		if (errorPtr) *errorPtr = resultError;
		
		return resultAF;
	}
	
	if (isIPv6Deactivated && !resolvedIPv4Address)
	{
		NSString *msg = @"IPv6 has been deactivated due to bind/connect, and DNS lookup found no IPv4 address(es).";
		resultError = [self otherError:msg];
		
		if (addressPtr) *addressPtr = resultAddress;
		if (errorPtr) *errorPtr = resultError;
		
		return resultAF;
	}
	
	// Extract first IPv4 and IPv6 address in list
	
	BOOL ipv4WasFirstInList = YES;
	NSData *address4 = nil;
	NSData *address6 = nil;
	
	for (NSData *address in addresses)
	{
		int af = [[self class] familyFromAddress:address];
		
		if (af == AF_INET)
		{
			if (address4 == nil)
			{
				address4 = address;
				
				if (address6)
					break;
				else
					ipv4WasFirstInList = YES;
			}
		}
		else // af == AF_INET6
		{
			if (address6 == nil)
			{
				address6 = address;
				
				if (address4)
					break;
				else
					ipv4WasFirstInList = NO;
			}
		}
	}
	
	// Determine socket type
	
	BOOL preferIPv4 = (config & kPreferIPv4) ? YES : NO;
	BOOL preferIPv6 = (config & kPreferIPv6) ? YES : NO;
	
	BOOL useIPv4 = ((preferIPv4 && address4) || (address6 == nil));
	BOOL useIPv6 = ((preferIPv6 && address6) || (address4 == nil));
	
	NSAssert(!(preferIPv4 && preferIPv6), @"Invalid config state");
	NSAssert(!(useIPv4 && useIPv6), @"Invalid logic");
	
	if (useIPv4 || (!useIPv6 && ipv4WasFirstInList))
	{
		resultAF = AF_INET;
		resultAddress = address4;
	}
	else
	{
		resultAF = AF_INET6;
		resultAddress = address6;
	}
	
	if (addressPtr) *addressPtr = resultAddress;
	if (errorPtr) *errorPtr = resultError;
		
	return resultAF;
}

/**
 * Finds the address(es) of an interface description.
 * An inteface description may be an interface name (en0, en1, lo0) or corresponding IP (192.168.4.34).
**/
- (void)convertIntefaceDescription:(NSString *)interfaceDescription
                              port:(uint16_t)port
                      intoAddress4:(NSData **)interfaceAddr4Ptr
                          address6:(NSData **)interfaceAddr6Ptr
{
	NSData *addr4 = nil;
	NSData *addr6 = nil;
	
	if (interfaceDescription == nil)
	{
		// ANY address
		
		struct sockaddr_in sockaddr4;
		memset(&sockaddr4, 0, sizeof(sockaddr4));
		
		sockaddr4.sin_len         = sizeof(sockaddr4);
		sockaddr4.sin_family      = AF_INET;
		sockaddr4.sin_port        = htons(port);
		sockaddr4.sin_addr.s_addr = htonl(INADDR_ANY);
		
		struct sockaddr_in6 sockaddr6;
		memset(&sockaddr6, 0, sizeof(sockaddr6));
		
		sockaddr6.sin6_len       = sizeof(sockaddr6);
		sockaddr6.sin6_family    = AF_INET6;
		sockaddr6.sin6_port      = htons(port);
		sockaddr6.sin6_addr      = in6addr_any;
		
		addr4 = [NSData dataWithBytes:&sockaddr4 length:sizeof(sockaddr4)];
		addr6 = [NSData dataWithBytes:&sockaddr6 length:sizeof(sockaddr6)];
	}
	else if ([interfaceDescription isEqualToString:@"localhost"] ||
	         [interfaceDescription isEqualToString:@"loopback"])
	{
		// LOOPBACK address
		
		struct sockaddr_in sockaddr4;
		memset(&sockaddr4, 0, sizeof(sockaddr4));
		
		sockaddr4.sin_len         = sizeof(struct sockaddr_in);
		sockaddr4.sin_family      = AF_INET;
		sockaddr4.sin_port        = htons(port);
		sockaddr4.sin_addr.s_addr = htonl(INADDR_LOOPBACK);
		
		struct sockaddr_in6 sockaddr6;
		memset(&sockaddr6, 0, sizeof(sockaddr6));
		
		sockaddr6.sin6_len       = sizeof(struct sockaddr_in6);
		sockaddr6.sin6_family    = AF_INET6;
		sockaddr6.sin6_port      = htons(port);
		sockaddr6.sin6_addr      = in6addr_loopback;
		
		addr4 = [NSData dataWithBytes:&sockaddr4 length:sizeof(sockaddr4)];
		addr6 = [NSData dataWithBytes:&sockaddr6 length:sizeof(sockaddr6)];
	}
	else
	{
		const char *iface = [interfaceDescription UTF8String];
		
		struct ifaddrs *addrs;
		const struct ifaddrs *cursor;
		
		if ((getifaddrs(&addrs) == 0))
		{
			cursor = addrs;
			while (cursor != NULL)
			{
				if ((addr4 == nil) && (cursor->ifa_addr->sa_family == AF_INET))
				{
					// IPv4
					
					struct sockaddr_in *addr = (struct sockaddr_in *)cursor->ifa_addr;
					
					if (strcmp(cursor->ifa_name, iface) == 0)
					{
						// Name match
						
						struct sockaddr_in nativeAddr4 = *addr;
						nativeAddr4.sin_port = htons(port);
						
						addr4 = [NSData dataWithBytes:&nativeAddr4 length:sizeof(nativeAddr4)];
					}
					else
					{
						char ip[INET_ADDRSTRLEN];
						
						const char *conversion;
						conversion = inet_ntop(AF_INET, &addr->sin_addr, ip, sizeof(ip));
						
						if ((conversion != NULL) && (strcmp(ip, iface) == 0))
						{
							// IP match
							
							struct sockaddr_in nativeAddr4 = *addr;
							nativeAddr4.sin_port = htons(port);
							
							addr4 = [NSData dataWithBytes:&nativeAddr4 length:sizeof(nativeAddr4)];
						}
					}
				}
				else if ((addr6 == nil) && (cursor->ifa_addr->sa_family == AF_INET6))
				{
					// IPv6
					
					struct sockaddr_in6 *addr = (struct sockaddr_in6 *)cursor->ifa_addr;
					
					if (strcmp(cursor->ifa_name, iface) == 0)
					{
						// Name match
						
						struct sockaddr_in6 nativeAddr6 = *addr;
						nativeAddr6.sin6_port = htons(port);
						
						addr6 = [NSData dataWithBytes:&nativeAddr6 length:sizeof(nativeAddr6)];
					}
					else
					{
						char ip[INET6_ADDRSTRLEN];
						
						const char *conversion;
						conversion = inet_ntop(AF_INET6, &addr->sin6_addr, ip, sizeof(ip));
						
						if ((conversion != NULL) && (strcmp(ip, iface) == 0))
						{
							// IP match
							
							struct sockaddr_in6 nativeAddr6 = *addr;
							nativeAddr6.sin6_port = htons(port);
							
							addr6 = [NSData dataWithBytes:&nativeAddr6 length:sizeof(nativeAddr6)];
						}
					}
				}
				
				cursor = cursor->ifa_next;
			}
			
			freeifaddrs(addrs);
		}
	}
	
	if (interfaceAddr4Ptr) *interfaceAddr4Ptr = addr4;
	if (interfaceAddr6Ptr) *interfaceAddr6Ptr = addr6;
}

/**
 * Converts a numeric hostname into its corresponding address.
 * The hostname is expected to be an IPv4 or IPv6 address represented as a human-readable string. (e.g. 192.168.4.34)
**/
- (void)convertNumericHost:(NSString *)numericHost
                      port:(uint16_t)port
              intoAddress4:(NSData **)addr4Ptr
                  address6:(NSData **)addr6Ptr
{
	NSData *addr4 = nil;
	NSData *addr6 = nil;
	
	if (numericHost)
	{
		NSString *portStr = [NSString stringWithFormat:@"%hu", port];
		
		struct addrinfo hints, *res, *res0;
		
		memset(&hints, 0, sizeof(hints));
		hints.ai_family   = PF_UNSPEC;
		hints.ai_socktype = SOCK_DGRAM;
		hints.ai_protocol = IPPROTO_UDP;
		hints.ai_flags    = AI_NUMERICHOST; // No name resolution should be attempted
		
		if (getaddrinfo([numericHost UTF8String], [portStr UTF8String], &hints, &res0) == 0)
		{
			for (res = res0; res; res = res->ai_next)
			{
				if ((addr4 == nil) && (res->ai_family == AF_INET))
				{
					// Found IPv4 address
					// Wrap the native address structure
					addr4 = [NSData dataWithBytes:res->ai_addr length:res->ai_addrlen];
				}
				else if ((addr6 == nil) && (res->ai_family == AF_INET6))
				{
					// Found IPv6 address
					// Wrap the native address structure
					addr6 = [NSData dataWithBytes:res->ai_addr length:res->ai_addrlen];
				}
			}
			freeaddrinfo(res0);
		}
	}
	
	if (addr4Ptr) *addr4Ptr = addr4;
	if (addr6Ptr) *addr6Ptr = addr6;
}

- (BOOL)isConnectedToAddress4:(NSData *)someAddr4
{
	NSAssert(dispatch_get_current_queue() == socketQueue, @"Must be dispatched on socketQueue");
	NSAssert(flags & kDidConnect, @"Not connected");
	NSAssert(cachedConnectedAddress, @"Expected cached connected address");
	
	if (cachedConnectedFamily != AF_INET)
	{
		return NO;
	}
	
	const struct sockaddr_in *sSockaddr4 = (struct sockaddr_in *)[someAddr4 bytes];
	const struct sockaddr_in *cSockaddr4 = (struct sockaddr_in *)[cachedConnectedAddress bytes];
	
	if (memcmp(&sSockaddr4->sin_addr, &cSockaddr4->sin_addr, sizeof(struct in_addr)) != 0)
	{
		return NO;
	}
	if (memcmp(&sSockaddr4->sin_port, &cSockaddr4->sin_port, sizeof(in_port_t)) != 0)
	{
		return NO;
	}
	
	return YES;
}

- (BOOL)isConnectedToAddress6:(NSData *)someAddr6
{
	NSAssert(dispatch_get_current_queue() == socketQueue, @"Must be dispatched on socketQueue");
	NSAssert(flags & kDidConnect, @"Not connected");
	NSAssert(cachedConnectedAddress, @"Expected cached connected address");
	
	if (cachedConnectedFamily != AF_INET6)
	{
		return NO;
	}
	
	const struct sockaddr_in6 *sSockaddr6 = (struct sockaddr_in6 *)[someAddr6 bytes];
	const struct sockaddr_in6 *cSockaddr6 = (struct sockaddr_in6 *)[cachedConnectedAddress bytes];
	
	if (memcmp(&sSockaddr6->sin6_addr, &cSockaddr6->sin6_addr, sizeof(struct in6_addr)) != 0)
	{
		return NO;
	}
	if (memcmp(&sSockaddr6->sin6_port, &cSockaddr6->sin6_port, sizeof(in_port_t)) != 0)
	{
		return NO;
	}
	
	return YES;
}

- (unsigned int)indexOfInterfaceAddr4:(NSData *)interfaceAddr4
{
	if (interfaceAddr4 == nil)
		return 0;
	if ([interfaceAddr4 length] != sizeof(struct sockaddr_in))
		return 0;
	
	int result = 0;
	struct sockaddr_in *ifaceAddr = (struct sockaddr_in *)[interfaceAddr4 bytes];
	
	struct ifaddrs *addrs;
	const struct ifaddrs *cursor;
	
	if ((getifaddrs(&addrs) == 0))
	{
		cursor = addrs;
		while (cursor != NULL)
		{
			if (cursor->ifa_addr->sa_family == AF_INET)
			{
				// IPv4
				
				struct sockaddr_in *addr = (struct sockaddr_in *)cursor->ifa_addr;
				
				if (memcmp(&addr->sin_addr, &ifaceAddr->sin_addr, sizeof(struct in_addr)) == 0)
				{
					result = if_nametoindex(cursor->ifa_name);
					break;
				}
			}
			
			cursor = cursor->ifa_next;
		}
		
		freeifaddrs(addrs);
	}
	
	return result;
}

- (unsigned int)indexOfInterfaceAddr6:(NSData *)interfaceAddr6
{
	if (interfaceAddr6 == nil)
		return 0;
	if ([interfaceAddr6 length] != sizeof(struct sockaddr_in6))
		return 0;
	
	int result = 0;
	struct sockaddr_in6 *ifaceAddr = (struct sockaddr_in6 *)[interfaceAddr6 bytes];
	
	struct ifaddrs *addrs;
	const struct ifaddrs *cursor;
	
	if ((getifaddrs(&addrs) == 0))
	{
		cursor = addrs;
		while (cursor != NULL)
		{
			if (cursor->ifa_addr->sa_family == AF_INET6)
			{
				// IPv6
				
				struct sockaddr_in6 *addr = (struct sockaddr_in6 *)cursor->ifa_addr;
				
				if (memcmp(&addr->sin6_addr, &ifaceAddr->sin6_addr, sizeof(struct in6_addr)) == 0)
				{
					result = if_nametoindex(cursor->ifa_name);
					break;
				}
			}
			
			cursor = cursor->ifa_next;
		}
		
		freeifaddrs(addrs);
	}
	
	return result;
}

- (void)setupSendAndReceiveSourcesForSocket4
{
	LogTrace();
	NSAssert(dispatch_get_current_queue() == socketQueue, @"Must be dispatched on socketQueue");
	
	send4Source = dispatch_source_create(DISPATCH_SOURCE_TYPE_WRITE, socket4FD, 0, socketQueue);
	receive4Source = dispatch_source_create(DISPATCH_SOURCE_TYPE_READ, socket4FD, 0, socketQueue);
	
	// Setup event handlers
	
	dispatch_source_set_event_handler(send4Source, ^{ @autoreleasepool {
		
		LogVerbose(@"send4EventBlock");
		LogVerbose(@"dispatch_source_get_data(send4Source) = %lu", dispatch_source_get_data(send4Source));
		
		flags |= kSock4CanAcceptBytes;
		
		// If we're ready to send data, do so immediately.
		// Otherwise pause the send source or it will continue to fire over and over again.
		
		if (currentSend == nil)
		{
			LogVerbose(@"Nothing to send");
			[self suspendSend4Source];
		}
		else if (currentSend->resolveInProgress)
		{
			LogVerbose(@"currentSend - waiting for address resolve");
			[self suspendSend4Source];
		}
		else if (currentSend->filterInProgress)
		{
			LogVerbose(@"currentSend - waiting on sendFilter");
			[self suspendSend4Source];
		}
		else
		{
			[self doSend];
		}
		
	}});
	
	dispatch_source_set_event_handler(receive4Source, ^{ @autoreleasepool {
		
		LogVerbose(@"receive4EventBlock");
		
		socket4FDBytesAvailable = dispatch_source_get_data(receive4Source);
		LogVerbose(@"socket4FDBytesAvailable: %lu", socket4FDBytesAvailable);
		
		if (socket4FDBytesAvailable > 0)
			[self doReceive];
		else
			[self doReceiveEOF];
		
	}});
	
	// Setup cancel handlers
	
	__block int socketFDRefCount = 2;
	
	int theSocketFD = socket4FD;
	
	#if NEEDS_DISPATCH_RETAIN_RELEASE
	dispatch_source_t theSendSource = send4Source;
	dispatch_source_t theReceiveSource = receive4Source;
	#endif
	
	dispatch_source_set_cancel_handler(send4Source, ^{
		
		LogVerbose(@"send4CancelBlock");
		
		#if NEEDS_DISPATCH_RETAIN_RELEASE
		LogVerbose(@"dispatch_release(send4Source)");
		dispatch_release(theSendSource);
		#endif
		
		if (--socketFDRefCount == 0)
		{
			LogVerbose(@"close(socket4FD)");
			close(theSocketFD);
		}
	});
	
	dispatch_source_set_cancel_handler(receive4Source, ^{
		
		LogVerbose(@"receive4CancelBlock");
		
		#if NEEDS_DISPATCH_RETAIN_RELEASE
		LogVerbose(@"dispatch_release(receive4Source)");
		dispatch_release(theReceiveSource);
		#endif
		
		if (--socketFDRefCount == 0)
		{
			LogVerbose(@"close(socket4FD)");
			close(theSocketFD);
		}
	});
	
	// We will not be able to receive until the socket is bound to a port,
	// either explicitly via bind, or implicitly by connect or by sending data.
	// 
	// But we should be able to send immediately.
	
	socket4FDBytesAvailable = 0;
	flags |= kSock4CanAcceptBytes;
	
	flags |= kSend4SourceSuspended;
	flags |= kReceive4SourceSuspended;
}

- (void)setupSendAndReceiveSourcesForSocket6
{
	LogTrace();
	NSAssert(dispatch_get_current_queue() == socketQueue, @"Must be dispatched on socketQueue");
	
	send6Source = dispatch_source_create(DISPATCH_SOURCE_TYPE_WRITE, socket6FD, 0, socketQueue);
	receive6Source = dispatch_source_create(DISPATCH_SOURCE_TYPE_READ, socket6FD, 0, socketQueue);
	
	// Setup event handlers
	
	dispatch_source_set_event_handler(send6Source, ^{ @autoreleasepool {
		
		LogVerbose(@"send6EventBlock");
		LogVerbose(@"dispatch_source_get_data(send6Source) = %lu", dispatch_source_get_data(send6Source));
		
		flags |= kSock6CanAcceptBytes;
		
		// If we're ready to send data, do so immediately.
		// Otherwise pause the send source or it will continue to fire over and over again.
		
		if (currentSend == nil)
		{
			LogVerbose(@"Nothing to send");
			[self suspendSend6Source];
		}
		else if (currentSend->resolveInProgress)
		{
			LogVerbose(@"currentSend - waiting for address resolve");
			[self suspendSend6Source];
		}
		else if (currentSend->filterInProgress)
		{
			LogVerbose(@"currentSend - waiting on sendFilter");
			[self suspendSend6Source];
		}
		else
		{
			[self doSend];
		}
		
	}});
	
	dispatch_source_set_event_handler(receive6Source, ^{ @autoreleasepool {
		
		LogVerbose(@"receive6EventBlock");
		
		socket6FDBytesAvailable = dispatch_source_get_data(receive6Source);
		LogVerbose(@"socket6FDBytesAvailable: %lu", socket6FDBytesAvailable);
		
		if (socket6FDBytesAvailable > 0)
			[self doReceive];
		else
			[self doReceiveEOF];
		
	}});
	
	// Setup cancel handlers
	
	__block int socketFDRefCount = 2;
	
	int theSocketFD = socket6FD;
	
	#if NEEDS_DISPATCH_RETAIN_RELEASE
	dispatch_source_t theSendSource = send6Source;
	dispatch_source_t theReceiveSource = receive6Source;
	#endif
	
	dispatch_source_set_cancel_handler(send6Source, ^{
		
		LogVerbose(@"send6CancelBlock");
		
		#if NEEDS_DISPATCH_RETAIN_RELEASE
		LogVerbose(@"dispatch_release(send6Source)");
		dispatch_release(theSendSource);
		#endif
		
		if (--socketFDRefCount == 0)
		{
			LogVerbose(@"close(socket6FD)");
			close(theSocketFD);
		}
	});
	
	dispatch_source_set_cancel_handler(receive6Source, ^{
		
		LogVerbose(@"receive6CancelBlock");
		
		#if NEEDS_DISPATCH_RETAIN_RELEASE
		LogVerbose(@"dispatch_release(receive6Source)");
		dispatch_release(theReceiveSource);
		#endif
		
		if (--socketFDRefCount == 0)
		{
			LogVerbose(@"close(socket6FD)");
			close(theSocketFD);
		}
	});
	
	// We will not be able to receive until the socket is bound to a port,
	// either explicitly via bind, or implicitly by connect or by sending data.
	// 
	// But we should be able to send immediately.
	
	socket6FDBytesAvailable = 0;
	flags |= kSock6CanAcceptBytes;
	
	flags |= kSend6SourceSuspended;
	flags |= kReceive6SourceSuspended;
}

- (BOOL)createSocket4:(BOOL)useIPv4 socket6:(BOOL)useIPv6 error:(NSError **)errPtr
{
	LogTrace();
	
	NSAssert(dispatch_get_current_queue() == socketQueue, @"Must be dispatched on socketQueue");
	NSAssert(((flags & kDidCreateSockets) == 0), @"Sockets have already been created");
	
	// CreateSocket Block
	// This block will be invoked below.
	
	int(^createSocket)(int) = ^