Re: [twsocket] Multicast question

[Éric Fleming Bonilha]

Hi Emanuele,

Thanks for the examples
I actually have a working application with multicast, but I was wondering if 
it was correct, because I tested it with a switch that manages IGMP and no 
multicast groups were being created.

I saw that you set TTL to 32, why? The default 1 would not work? I know that 
1 would work just on local network (My case)

What I´m confused is with the group creation, how my ICS based application 
with create a multicast group that is visible for switches (By using IGMP) 
and switches can manage this multicast distribution? Without that, multicast 
would be just like broadcast.

I saw on TWSocket source that when I start listening it actually sets the 
socket to ADD_MEMBERSHIP tp the group, this may be OK for receiving data, 
but I´m confused about sending multicast data, because the sender is the one 
that was supposed to create the multicast group right? But to send multicast 
data on network I need to use Connect method instead of Listen from the 
TWSocket, in this case, on Connect method I didn´t find a mention to 
ADD_MEMBERSHIP or creating a multicast group.

Thanks
Eric


-----Mensagem Original----- 
From: emanuele bizzarri
Sent: Thursday, May 26, 2011 3:41 AM
To: twsocket@elists.org
Subject: Re: [twsocket] Multicast question

Hi,
this is an example of TUDP class that can be used in multicast (receive
and transmit).
This unit depends by other units, but you can easily extract what you need.
Note that I set multicast ttl.
I hope it will be usefull for you,
Bye
Emanuele


unit ewPlatform_UDP;

interface

uses
 ewPlatform_Lists,
 ewPlatform_Logger,
 ewPlatform_Memory,
 ewPlatform_Packets,
 ewPlatform_Strings,
 OverByteIcsWsocket,
 WinSock,
 Windows,
 SysUtils,
 Classes;

type
 TOnUDPError=procedure(aError:integer)of object;
 TOnUDPDataSent=procedure(aInteger:integer)of object;

TOnUDPDataAvailable=procedure(aSender:TObject;aData:pointer;aSize:integer;aPeerIP:string;aPeerPort:integer)
of object;
 TUDP=class
 protected
   fWS:TWSocket;
   fSent:boolean;
   fPeerSrc:TSockAddr;
   fPeerSrcLen:integer;
   fRxData:pointer;
   fRxSize:integer;
   fWhiteList:TStringList;
   fBlackList:TStringList;
   fTxList:TStringList;
   procedure DataAvailable(aSender:TObject;aError:word);
   procedure DataSent(aSender:TObject;aErrCode:word);
   procedure DnsLookupDone(aSender:TObject;aErrCode:word);
   procedure ChangeState(aSender:TObject;aOldState,aNewState:TSocketState);
   procedure Send;
   function GetStarted:boolean;
 public
   pLocalIP:string;
   pLocalPort:integer;
   pPeerIP:string;
   pPeerPort:integer;
   pMultiThreaded:boolean;
   pMulticast:boolean;
   pUseWhiteList:boolean;
   pUseBlackList:boolean;
   pMulticastTTL:integer;

   pGetPeerByData:boolean;
   pOnDataSent:TOnUDPDataSent;
   pOnDataAvailable:TOnUDPDataAvailable;
   pOnError:TOnUDPError;
   pOnChangeState:TChangeState;

   constructor Create;
   destructor Destroy;override;
   procedure StartRx;
   procedure SetTx;
   procedure Disconnect;
   procedure Connect;
   function Add2WhiteList(aIPPort:string):boolean;
   function Add2BlackList(aIPPort:string):boolean;
   procedure DeleteFromWhiteList(aIPPort:string);
   procedure DeleteFromBlackList(aIPPort:string);
   procedure ClearWhiteList;
   procedure ClearBlackList;
   function NewData(aData:pointer;aSize:integer):integer;

   property pStarted:boolean read GetStarted;

   end;

implementation

//------------------------------------------------------------------------------
//TUDP
//------------------------------------------------------------------------------
constructor TUDP.Create;
begin
 inherited Create;
 TLogger.Log('UDP socket creation
threadID='+inttostr(GetCurrentThreadID),lsVerbose,true);
 fWS:=TWSocket.Create(nil);
 fWS.OnDataAvailable:=DataAvailable;
 fWS.OnDataSent:=DataSent;
 fWS.OnDnsLookupDone:=DnsLookUpDone;
 fWS.OnChangeState:=ChangeState;
 fWS.Proto:='udp';

 pGetPeerByData:=false;
 fTxList:=TStringList.Create;
 fSent:=false;

 pLocalIP:='0.0.0.0';
 pLocalPort:=0;
 pPeerIP:='';
 pPeerPort:=0;
 pMultiThreaded:=false;
 pMulticast:=false;
 pMulticastTTL:=32;

 fWhiteList:=TStringList.Create;
 fBlackList:=TStringList.Create;
 pUseWhiteList:=false;
 pUseBlackList:=false;

 fRxSize:=256*1024;
 getmem(fRxData,fRxSize);

 fPeerSrcLen:=sizeof(fPeerSrc);
end;

destructor TUDP.Destroy;
begin
 Disconnect;
 FreeObjAndNil(fWS);
 FreeMemAndNil(fRxData);
 FreeObjAndNil(fWhiteList);
 FreeObjAndNil(fBlackList);
 FreeList(fTxList);
 FreeObjAndNil(fTxList);
 inherited Destroy;
end;

procedure TUDP.StartRx;
begin
 Disconnect;
 pLocalIP:=trim(pLocalIP);
 if (pLocalIP<>'')and(pLocalPort>0) then
 begin
   fWS.Proto:='udp';
   fWS.MultiThreaded:=pMultiThreaded;
   fWS.Addr:=pLocalIP;
   fWS.Port:=inttostr(pLocalPort);
   if fWS.Addr='' then
     fWS.Addr:='0.0.0.0';
   if pMulticast then
   begin
     fWS.MultiCast:=true;
     fWS.ReuseAddr:=true;
     fWS.MultiCastAddrStr:=pPeerIP;
   end;
   fWS.Listen;
   fWS.SocketRcvBufSize:=fRXSize;
   if pMulticast then

setsockopt(fWS.HSocket,IPPROTO_IP,IP_MULTICAST_TTL,@pMulticastTTL,sizeof(pMulticastTTL));
 end
 else
   TLogger.Log('UDP socket start rx error LocalIP='+pLocalIP+'
LocalPort='+inttostr(pLocalPort),lsError,true);
end;

function TUDP.GetStarted:boolean;
begin
 result:=false;
 if (assigned(fWS)) then
   result:=(fWS.State=wsListening)or(fWS.State=wsConnected);
end;

procedure TUDP.SetTx;
var
 lRes:boolean;
begin
 pPeerIP:=trim(pPeerIP);
 lRes:=(pPeerIp<>'')and(pPeerPort>0);
 TLogger.Log('UDP socket set tx PeerIP='+pPeerIP+'
PeerPort='+inttostr(pPeerPort)+'...
'+Boolean2Str(lRes,'ok','ko'),Boolean2Severity(lRes,lsVerbose,lsError),true);
 fPeerSrc.sin_family:=AF_INET;
 fPeerSrc.sin_addr.s_addr:=WSocket_inet_addr(AnsiString(pPeerIP));
 fPeerSrc.sin_port:=htons(word(pPeerPort));
 fSent:=false;
 FreeList(fTxList);
end;

procedure TUDP.Disconnect;
begin
 fWS.Shutdown(SD_BOTH);
 fWS.Close;
 FreeList(fTxList);
 fSent:=false;
end;

procedure TUDP.Connect;
begin
 Disconnect;
 fWS.Proto:='udp';
 fWS.MultiThreaded:=pMultiThreaded;
 fWS.LocalAddr:=pLocalIP;
 fWS.Addr:=trim(pPeerIP);
 fWS.Port:=inttostr(pPeerPort);
 SetTx;
 if (fWS.Addr<>'')and(pPeerPort>0) then
   fWS.DnsLookup(fWS.Addr);
end;

procedure TUDP.DnsLookupDone(aSender:TObject;aErrCode:word);
begin
 //se riesco a risolvere l'host mi connetto
 if aErrCode=0 then
 begin
   fWS.Connect;
   fWS.SocketRcvBufSize:=fRXSize;
 end;
end;

procedure
TUDP.ChangeState(aSender:TObject;aOldState,aNewState:TSocketState);
begin
 if assigned(pOnChangeState) then
   pOnChangeState(self,aOldState,aNewState);
end;

function TUDP.NewData(aData:pointer;aSize:integer):integer;
var
 lItem:TBufferItem;
begin
 result:=0;
 if (pPeerIP<>'')and(GetStarted) then
 begin
   lItem:=TBufferItem.Create(aData,aSize,0,0);
   fTxList.AddObject(inttostr(aSize),lItem);
   Send;
 end;
end;

procedure TUDP.Send;
var
 lItem:TBufferItem;
begin
 if (not fSent)and(fTxList.Count>0) then
 begin
   lItem:=TBufferItem(fTxList.Objects[0]);
   if (fWS.SendTo(fPeerSrc,fPeerSrcLen,lItem.pData,lItem.pSize)>0)or
      (WSocket_WSAGetLastError=WSAEWOULDBLOCK)
   then
     fSent:=true;
 end;
end;

procedure TUDP.DataSent(aSender:TObject;aErrCode:word);
var
 lItem:TBufferItem;
 lSize:integer;
begin
 if fSent then
 begin
   fSent:=false;
   lSIze:=0;
   if fTxList.Count>0 then
   begin
     lItem:=TBufferItem(fTxList.Objects[0]);
     if assigned(lItem) then
     begin
       lSize:=lItem.pSize;
       FreeObjAndNil(lItem);
     end;
     fTxList.Delete(0);
   end;
   if assigned(pOnDataSent) then
     pOnDataSent(lSize);
   Send;
 end;
end;

procedure TUDP.DataAvailable(aSender:TObject;aError:word);
var
 lSize:integer;
 lPeerSrc:TSockAddrIn;
 lPeerSrcLen:integer;
 lPeerIP:string;
 lPeerPort:integer;
 lValidPeer:boolean;
begin
 lPeerSrcLen:=sizeof(lPeerSrc);
 lSize:=fWS.ReceiveFrom(fRxData,fRxSize-2,lPeerSrc,lPeerSrcLen);
 if lSize<0 then
 begin
   {
   WSAEWOULDBLOCK=10035
   Resource temporarily unavailable.
   This error is returned from operations on nonblocking sockets that
cannot
   be completed immediately, for example recv when no data is queued to be
   read from the socket. It is a nonfatal error, and the operation
should be
   retried later. It is normal for WSAEWOULDBLOCK to be reported as the
   result from calling connect on a nonblocking SOCK_STREAM socket,
   since some time must elapse for the connection to be established.
   }
   {
   WSAECONNRESET=10054
   Connection reset by peer.
   An existing connection was forcibly closed by the remote host. This
normally
   results if the peer application on the remote host is suddenly stopped,
   the host is rebooted, the host or remote network interface is disabled,
   or the remote host uses a hard close (see setsockopt for more
   information on the SO_LINGER option on the remote socket). This
error may
   also result if a connection was broken due to keep-alive activity
detecting a
   failure while one or more operations are in progress. Operations that
   were in progress fail with WSAENETRESET. Subsequent operations
   fail with WSAECONNRESET.
   }
   if assigned(pOnError) then
     pOnError(WSocket_WSAGetLastError);
 end
 else
 begin
   lPeerIP:=string(AnsiString(inet_ntoa(lPeerSrc.sin_addr)));
   lPeerPort:=ntohs(lPeerSrc.sin_port);

   if pGetPeerByData then
   begin
     pGetPeerByData:=false;
     pPeerIP:=lPeerIP;
     pPeerPort:=lPeerPort;
     SetTx;
   end;
   lValidPeer:=true;
   if pUseWhiteList then
   begin

lValidPeer:=(fWhiteList.IndexOf(lPeerIP+':'+inttostr(lPeerPort))>=0)or(fWhiteList.IndexOf(lPeerIP+':*')>=0);
   end;
   if (lValidPeer)and(pUseBlackList) then

lValidPeer:=(fBlackList.IndexOf(lPeerIP+':'+inttostr(lPeerPort))<0)and(fBlackList.IndexOf(lPeerIP+':*')<0);
   if lValidPeer then
   begin
     PAnsiChar(fRxData)[lSize]:=#0;
     PAnsiChar(fRxData)[lSize+1]:=#0;
     if assigned(pOnDataAvailable) then
       pOnDataAvailable(self,fRxData,lSize,lPeerIP,lPeerPort);
   end;
 end;
end;

function TUDP.Add2WhiteList(aIPPort:string):boolean;
begin
 result:=false;
 DeleteFromBlackList(aIPPort);
 if fWhiteList.IndexOf(aIPPort)<0 then
 begin
   fWhiteList.Add(aIPPort);
   result:=true;
 end;
end;

function TUDP.Add2BlackList(aIPPort:string):boolean;
begin
 result:=false;
 DeleteFromWhiteList(aIPPort);
 if fBlackList.IndexOf(aIPPort)<0 then
 begin
   fBlackList.Add(aIPPort);
   result:=true;
 end;
end;

procedure TUDP.DeleteFromWhiteList(aIPPort:string);
var
 lIndex:integer;
begin
 lIndex:=fWhiteList.IndexOf(aIPPort);
 if lIndex>=0 then
   fWhiteList.Delete(lIndex);
end;

procedure TUDP.DeleteFromBlackList(aIPPort:string);
var
 lIndex:integer;
begin
 lIndex:=fBlackList.IndexOf(aIPPort);
 if lIndex>=0 then
   fBlackList.Delete(lIndex);
end;

procedure TUDP.ClearWhiteList;
begin
 fWhiteList.Clear;
end;

procedure TUDP.ClearBlackList;
begin
 fBlackList.Clear;
end;

end.

Il 26/05/2011 06:48, Éric Fleming Bonilha ha scritto:
Hi

I´m wondering how to use ICS properly to send and receive Multicast data. 
Where can I find example for multicast and ICS?

I´m in doubt about the IGMP protocol, do I need to implement anything on 
application layer or does IGMP protocol is implemented on underlying stack 
automatically?

How my application will create a multicast group on network and/or join a 
group?

Thank you very much!
Eric
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--
Ing. Emanuele Bizzarri
Software Development Department
e-works s.r.l.
41011 - Campogalliano - Modena - Italy
tel. +39 059 2929081 int. 23
fax +39 059 2925035

e-mail: e.bizza...@e-works.it - http://www.e-works.it
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