text: //
  //  AsyncUdpSocket.h
  //  
  //  This class is in the public domain.
  //  Originally created by Robbie Hanson on Wed Oct 01 2008.
  //  Updated and maintained by Deusty Designs and the Mac development community.
  //
  //  http://code.google.com/p/cocoaasyncsocket/
  //
  
  #import <Foundation/Foundation.h>
  
  @class AsyncSendPacket;
  @class AsyncReceivePacket;
  
  extern NSString *const AsyncUdpSocketException;
  extern NSString *const AsyncUdpSocketErrorDomain;
  
  enum AsyncUdpSocketError
  {
  	AsyncUdpSocketCFSocketError = kCFSocketError,	// From CFSocketError enum
  	AsyncUdpSocketNoError = 0,                      // Never used
  	AsyncUdpSocketBadParameter,                     // Used if given a bad parameter (such as an improper address)
  	AsyncUdpSocketIPv4Unavailable,                  // Used if you bind/connect using IPv6 only
  	AsyncUdpSocketIPv6Unavailable,                  // Used if you bind/connect using IPv4 only (or iPhone)
  	AsyncUdpSocketSendTimeoutError,
  	AsyncUdpSocketReceiveTimeoutError
  };
  typedef enum AsyncUdpSocketError AsyncUdpSocketError;
  
  @interface AsyncUdpSocket : NSObject
  {
  	CFSocketRef theSocket4;            // IPv4 socket
  	CFSocketRef theSocket6;            // IPv6 socket
  	
  	CFRunLoopSourceRef theSource4;     // For theSocket4
  	CFRunLoopSourceRef theSource6;     // For theSocket6
  	CFRunLoopRef theRunLoop;
  	CFSocketContext theContext;
  	NSArray *theRunLoopModes;
  	
  	NSMutableArray *theSendQueue;
  	AsyncSendPacket *theCurrentSend;
  	NSTimer *theSendTimer;
  	
  	NSMutableArray *theReceiveQueue;
  	AsyncReceivePacket *theCurrentReceive;
  	NSTimer *theReceiveTimer;
  	
  	id theDelegate;
  	UInt16 theFlags;
  	
  	long theUserData;
  	
  	NSString *cachedLocalHost;
  	UInt16 cachedLocalPort;
  	
  	NSString *cachedConnectedHost;
  	UInt16 cachedConnectedPort;
  	
  	UInt32 maxReceiveBufferSize;
  }
  
  /**
   * Creates new instances of AsyncUdpSocket.
  **/
  - (id)init;
  - (id)initWithDelegate:(id)delegate;
  - (id)initWithDelegate:(id)delegate userData:(long)userData;
  
  /**
   * Creates new instances of AsyncUdpSocket that support only IPv4 or IPv6.
   * The other init methods will support both, unless specifically binded or connected to one protocol.
   * If you know you'll only be using one protocol, these init methods may be a bit more efficient.
  **/
  - (id)initIPv4;
  - (id)initIPv6;
  
  - (id)delegate;
  - (void)setDelegate:(id)delegate;
  
  - (long)userData;
  - (void)setUserData:(long)userData;
  
  /**
   * Returns the local address info for the socket.
   * 
   * Note: Address info may not be available until after the socket has been bind'ed,
   * or until after data has been sent.
  **/
  - (NSString *)localHost;
  - (UInt16)localPort;
  
  /**
   * Returns the remote address info for the socket.
   * 
   * Note: Since UDP is connectionless by design, connected address info
   * will not be available unless the socket is explicitly connected to a remote host/port
  **/
  - (NSString *)connectedHost;
  - (UInt16)connectedPort;
  
  /**
   * Returns whether or not this socket has been connected to a single host.
   * By design, UDP is a connectionless protocol, and connecting is not needed.
   * If connected, the socket will only be able to send/receive data to/from the connected host.
  **/
  - (BOOL)isConnected;
  
  /**
   * Returns whether or not this socket has been closed.
   * The only way a socket can be closed is if you explicitly call one of the close methods.
  **/
  - (BOOL)isClosed;
  
  /**
   * Returns whether or not this socket supports IPv4.
   * By default this will be true, unless the socket is specifically initialized as IPv6 only,
   * or is binded or connected to an IPv6 address.
  **/
  - (BOOL)isIPv4;
  
  /**
   * Returns whether or not this socket supports IPv6.
   * By default this will be true, unless the socket is specifically initialized as IPv4 only,
   * or is binded or connected to an IPv4 address.
   * 
   * This method will also return false on platforms that do not support IPv6.
   * Note: The iPhone does not currently support IPv6.
  **/
  - (BOOL)isIPv6;
  
  /**
   * Returns the mtu of the socket.
   * If unknown, returns zero.
   * 
   * Sending data larger than this may result in an error.
   * This is an advanced topic, and one should understand the wide range of mtu's on networks and the internet.
   * Therefore this method is only for reference and may be of little use in many situations.
  **/
  - (unsigned int)maximumTransmissionUnit;
  
  /**
   * Binds the UDP socket to the given port and optional address.
   * Binding should be done for server sockets that receive data prior to sending it.
   * Client sockets can skip binding,
   * as the OS will automatically assign the socket an available port when it starts sending data.
   * 
   * You cannot bind a socket after its been connected.
   * You can only bind a socket once.
   * You can still connect a socket (if desired) after binding.
   * 
   * On success, returns YES.
   * Otherwise returns NO, and sets errPtr. If you don't care about the error, you can pass nil for errPtr.
  **/
  - (BOOL)bindToPort:(UInt16)port error:(NSError **)errPtr;
  - (BOOL)bindToAddress:(NSString *)localAddr port:(UInt16)port error:(NSError **)errPtr;
  
  /**
   * Connects the UDP socket to the given host and port.
   * By design, UDP is a connectionless protocol, and connecting is not needed.
   * 
   * Choosing to connect to a specific host/port has the following effect:
   * - You will only be able to send data to the connected host/port.
   * - You will only be able to receive data from the connected host/port.
   * - You will receive ICMP messages that come from the connected host/port, such as "connection refused".
   * 
   * Connecting a UDP socket does not result in any communication on the socket.
   * It simply changes the internal state of the socket.
   * 
   * You cannot bind a socket after its been connected.
   * You can only connect a socket once.
   * 
   * On success, returns YES.
   * Otherwise returns NO, and sets errPtr. If you don't care about the error, you can pass nil for errPtr.
  **/
  - (BOOL)connectToHost:(NSString *)host onPort:(UInt16)port error:(NSError **)errPtr;
  - (BOOL)connectToAddress:(NSData *)remoteAddr error:(NSError **)errPtr;
  
  /**
   * Join multicast group
   *
   * Group should be an IP address (eg @"225.228.0.1")
  **/
  - (BOOL)joinMulticastGroup:(NSString *)group error:(NSError **)errPtr;
  - (BOOL)joinMulticastGroup:(NSString *)group withAddress:(NSString *)interface error:(NSError **)errPtr;
  
  /**
   * By default, the underlying socket in the OS will not allow you to send broadcast messages.
   * In order to send broadcast messages, you need to enable this functionality in the socket.
   * 
   * A broadcast is a UDP message to addresses like "192.168.255.255" or "255.255.255.255" that is
   * delivered to every host on the network.
   * The reason this is generally disabled by default is to prevent
   * accidental broadcast messages from flooding the network.
  **/
  - (BOOL)enableBroadcast:(BOOL)flag error:(NSError **)errPtr;
  
  /**
   * Asynchronously sends the given data, with the given timeout and tag.
   * 
   * This method may only be used with a connected socket.
   * 
   * If data is nil or zero-length, this method does nothing and immediately returns NO.
   * If the socket is not connected, this method does nothing and immediately returns NO.
  **/
  - (BOOL)sendData:(NSData *)data withTimeout:(NSTimeInterval)timeout tag:(long)tag;
  
  /**
   * Asynchronously sends the given data, with the given timeout and tag, to the given host and port.
   * 
   * This method cannot be used with a connected socket.
   * 
   * If data is nil or zero-length, this method does nothing and immediately returns NO.
   * If the socket is connected, this method does nothing and immediately returns NO.
   * If unable to resolve host to a valid IPv4 or IPv6 address, this method returns NO.
  **/
  - (BOOL)sendData:(NSData *)data toHost:(NSString *)host port:(UInt16)port withTimeout:(NSTimeInterval)timeout tag:(long)tag;
  
  /**
   * Asynchronously sends the given data, with the given timeout and tag, to the given address.
   * 
   * This method cannot be used with a connected socket.
   * 
   * If data is nil or zero-length, this method does nothing and immediately returns NO.
   * If the socket is connected, this method does nothing and immediately returns NO.
  **/
  - (BOOL)sendData:(NSData *)data toAddress:(NSData *)remoteAddr withTimeout:(NSTimeInterval)timeout tag:(long)tag;
  
  /**
   * Asynchronously receives a single datagram packet.
   * 
   * If the receive succeeds, the onUdpSocket:didReceiveData:fromHost:port:tag delegate method will be called.
   * Otherwise, a timeout will occur, and the onUdpSocket:didNotReceiveDataWithTag: delegate method will be called.
  **/
  - (void)receiveWithTimeout:(NSTimeInterval)timeout tag:(long)tag;
  
  /**
   * Closes the socket immediately. Any pending send or receive operations are dropped.
  **/
  - (void)close;
  
  /**
   * Closes after all pending send operations have completed.
   * After calling this, the sendData: and receive: methods will do nothing.
   * In other words, you won't be able to add any more send or receive operations to the queue.
   * The socket will close even if there are still pending receive operations.
  **/
  - (void)closeAfterSending;
  
  /**
   * Closes after all pending receive operations have completed.
   * After calling this, the sendData: and receive: methods will do nothing.
   * In other words, you won't be able to add any more send or receive operations to the queue.
   * The socket will close even if there are still pending send operations.
  **/
  - (void)closeAfterReceiving;
  
  /**
   * Closes after all pending send and receive operations have completed.
   * After calling this, the sendData: and receive: methods will do nothing.
   * In other words, you won't be able to add any more send or receive operations to the queue.
  **/
  - (void)closeAfterSendingAndReceiving;
  
  /**
   * Gets/Sets the maximum size of the buffer that will be allocated for receive operations.
   * The default size is 9216 bytes.
   * 
   * The theoretical maximum size of any IPv4 UDP packet is UINT16_MAX = 65535.
   * The theoretical maximum size of any IPv6 UDP packet is UINT32_MAX = 4294967295.
   * 
   * In practice, however, the size of UDP packets will be much smaller.
   * Indeed most protocols will send and receive packets of only a few bytes,
   * or will set a limit on the size of packets to prevent fragmentation in the IP layer.
   * 
   * If you set the buffer size too small, the sockets API in the OS will silently discard
   * any extra data, and you will not be notified of the error.
  **/
  - (UInt32)maxReceiveBufferSize;
  - (void)setMaxReceiveBufferSize:(UInt32)max;
  
  /**
   * When you create an AsyncUdpSocket, it is added to the runloop of the current thread.
   * So it is easiest to simply create the socket on the thread you intend to use it.
   * 
   * If, however, you need to move the socket to a separate thread at a later time, this
   * method may be used to accomplish the task.
   * 
   * This method must be called from the thread/runloop the socket is currently running on.
   * 
   * Note: After calling this method, all further method calls to this object should be done from the given runloop.
   * Also, all delegate calls will be sent on the given runloop.
  **/
  - (BOOL)moveToRunLoop:(NSRunLoop *)runLoop;
  
  /**
   * Allows you to configure which run loop modes the socket uses.
   * The default set of run loop modes is NSDefaultRunLoopMode.
   * 
   * If you'd like your socket to continue operation during other modes, you may want to add modes such as
   * NSModalPanelRunLoopMode or NSEventTrackingRunLoopMode. Or you may simply want to use NSRunLoopCommonModes.
   * 
   * Note: NSRunLoopCommonModes is defined in 10.5. For previous versions one can use kCFRunLoopCommonModes.
  **/
  - (BOOL)setRunLoopModes:(NSArray *)runLoopModes;
  
  /**
   * Returns the current run loop modes the AsyncSocket instance is operating in.
   * The default set of run loop modes is NSDefaultRunLoopMode.
  **/
  - (NSArray *)runLoopModes;
  
  @end
  
  ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
  #pragma mark -
  ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
  
  @protocol AsyncUdpSocketDelegate
  @optional
  
  /**
   * Called when the datagram with the given tag has been sent.
  **/
  - (void)onUdpSocket:(AsyncUdpSocket *)sock didSendDataWithTag:(long)tag;
  
  /**
   * Called if an error occurs while trying to send a datagram.
   * This could be due to a timeout, or something more serious such as the data being too large to fit in a sigle packet.
  **/
  - (void)onUdpSocket:(AsyncUdpSocket *)sock didNotSendDataWithTag:(long)tag dueToError:(NSError *)error;
  
  /**
   * Called when the socket has received the requested datagram.
   * 
   * Due to the nature of UDP, you may occasionally receive undesired packets.
   * These may be rogue UDP packets from unknown hosts,
   * or they may be delayed packets arriving after retransmissions have already occurred.
   * It's important these packets are properly ignored, while not interfering with the flow of your implementation.
   * As an aid, this delegate method has a boolean return value.
   * If you ever need to ignore a received packet, simply return NO,
   * and AsyncUdpSocket will continue as if the packet never arrived.
   * That is, the original receive request will still be queued, and will still timeout as usual if a timeout was set.
   * For example, say you requested to receive data, and you set a timeout of 500 milliseconds, using a tag of 15.
   * If rogue data arrives after 250 milliseconds, this delegate method would be invoked, and you could simply return NO.
   * If the expected data then arrives within the next 250 milliseconds,
   * this delegate method will be invoked, with a tag of 15, just as if the rogue data never appeared.
   * 
   * Under normal circumstances, you simply return YES from this method.
  **/
  - (BOOL)onUdpSocket:(AsyncUdpSocket *)sock
       didReceiveData:(NSData *)data
              withTag:(long)tag
             fromHost:(NSString *)host
                 port:(UInt16)port;
  
  /**
   * Called if an error occurs while trying to receive a requested datagram.
   * This is generally due to a timeout, but could potentially be something else if some kind of OS error occurred.
  **/
  - (void)onUdpSocket:(AsyncUdpSocket *)sock didNotReceiveDataWithTag:(long)tag dueToError:(NSError *)error;
  
  /**
   * Called when the socket is closed.
   * A socket is only closed if you explicitly call one of the close methods.
  **/
  - (void)onUdpSocketDidClose:(AsyncUdpSocket *)sock;
  
  @end
  