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MulticastSocket.d

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00001 /*******************************************************************************
00002 
00003         @file MulticastSocket.d
00004         
00005         Copyright (C) 2004 Kris Bell
00006         
00007         This software is provided 'as-is', without any express or implied
00008         warranty. In no event will the authors be held liable for damages
00009         of any kind arising from the use of this software.
00010         
00011         Permission is hereby granted to anyone to use this software for any 
00012         purpose, including commercial applications, and to alter it and/or 
00013         redistribute it freely, subject to the following restrictions:
00014         
00015         1. The origin of this software must not be misrepresented; you must 
00016            not claim that you wrote the original software. If you use this 
00017            software in a product, an acknowledgment within documentation of 
00018            said product would be appreciated but is not required.
00019 
00020         2. Altered source versions must be plainly marked as such, and must 
00021            not be misrepresented as being the original software.
00022 
00023         3. This notice may not be removed or altered from any distribution
00024            of the source.
00025 
00026 
00027                         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
00028 
00029 
00030         @version        Initial version, June 2004      
00031         @author         Kris
00032 
00033 
00034 *******************************************************************************/
00035 
00036 module mango.io.MulticastSocket;
00037 
00038 private import  mango.io.Socket,
00039                 mango.io.Buffer,
00040                 mango.io.Exception,
00041                 mango.io.DatagramSocket;
00042 
00043 /******************************************************************************
00044         
00045         Wrapper around multicast style of sockets, to simplify the API a
00046         bit, and to tie them into the IBuffer construct. Note that when used 
00047         with a SocketListener you must first join the MulticastSocket to a 
00048         group. Do not bind() it yourself, since that is performed by the 
00049         join() method.
00050 
00051 *******************************************************************************/
00052 
00053 class MulticastSocket : DatagramSocket
00054 {
00055         private InternetAddress groupAddress;
00056 
00057         /***********************************************************************
00058                 
00059                 Enable/disable the receipt of multicast packets send 
00060                 from the same socket
00061 
00062         ***********************************************************************/
00063 
00064         void setLoopback (bool loopback)
00065         {
00066                 uint[1] onoff = loopback;
00067                 setOption (OptionLevel.IP, Option.IP_MULTICAST_LOOP, onoff);
00068         }
00069 
00070         /***********************************************************************
00071 
00072                 Join a multicast group. This is necessary only for a 
00073                 multicast reciever (listener). You may call this for
00074                 a send-only socket without harm, but the operation is
00075                 completely superfluous.
00076 
00077                 Note that the socket will be bound to the specified port, 
00078                 and be listening on the provided class D address. Expect
00079                 join() to fail without a network adapter present, or the
00080                 NIC is not plugged into a router or switch.
00081 
00082         ***********************************************************************/
00083 
00084         void join (InternetAddress groupAddress)
00085         {
00086                 this.groupAddress = groupAddress;
00087 
00088                 setAddressReuse (true);
00089                 bind (new InternetAddress(groupAddress.port()));
00090                 resumeGroup ();
00091         }
00092 
00093         /***********************************************************************
00094         
00095                 Remove this socket from the current group. Method join()
00096                 is expected to have been invoked previously, otherwise 
00097                 this is a noop.
00098 
00099         ***********************************************************************/
00100 
00101         void pauseGroup ()
00102         {
00103                 if (groupAddress)
00104                     if (! setGroup (groupAddress, Option.IP_DROP_MEMBERSHIP))
00105                           exception ("Unable to leave multicast group.");
00106         }
00107 
00108         /***********************************************************************
00109 
00110                 Add this socket to the current group again. Method join()
00111                 is expected to have been invoked previously, otherwise 
00112                 this is a noop.
00113 
00114         ***********************************************************************/
00115 
00116         void resumeGroup ()
00117         {
00118                 if (groupAddress)
00119                     if (! setGroup (groupAddress, Option.IP_ADD_MEMBERSHIP))
00120                           exception ("Unable to join multicast group.");
00121         }
00122 
00123         /***********************************************************************
00124         
00125                 Leave a multicast group. This should only be invoked on
00126                 sockets that have already joined a multicast group, and
00127                 before said socket joins another group. 
00128 
00129                 There does not appear to be a means to unbind the socket
00130                 from the port specified during the original join(); thus
00131                 we have to create a new underlying socket before join()
00132                 will bind() cleanly.
00133 
00134         ***********************************************************************/
00135 
00136         void leave ()
00137         {
00138                 if (groupAddress)
00139                    {
00140                    pauseGroup ();
00141                    groupAddress = null;
00142 
00143                    // drop the original socket handle
00144                    closure();
00145 
00146                    // create a new socket for binding during another join(), since
00147                    // there doesn't appear to be a means of unbinding
00148                    create (Socket.AddressFamily.INET, Socket.Type.DGRAM, Socket.Protocol.IP);                
00149                    }
00150         }
00151 }

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