procedure TPortMapClientThread.DoTunneling(Peer1,Peer2:TCustomWinSocket);
 function SendBufFully(Peer:TCustomWinSocket;var Buf; Count: Integer):boolean;
 var pBuf:PByte;
   s:integer;
 begin
   result:=false;
   pBuf:=@Buf;
   while count>0 do
   begin
     s:=Peer2.SendBuf(pBuf^,Count);
     if s=0 then exit;
     inc(pBuf,s);
     dec(Count,s);
   end;
   result:=true;
 end;
var
 FDSet: TFDSet;
 TimeVal: TTimeVal;
 Buf:array[0..4095] of char;
 r:integer;
begin
 TimeVal.tv_sec := FPortMap.ClientTimeout div 1000;
 TimeVal.tv_usec := (FPortMap.ClientTimeout mod 1000) * 1000;
 while Peer1.Connected and Peer2.Connected do
 begin
   FD_ZERO(FDSet);
   FD_SET(Peer1.SocketHandle, FDSet);
   FD_SET(Peer2.SocketHandle, FDSet);
   if select(0, @FDSet, nil, nil, @TimeVal)>0 then
   begin
     if FD_ISSET(Peer1.SocketHandle, FDSet) then
     begin
       r:=Peer1.ReceiveBuf(Buf,Length(Buf));
       if r=0 then exit;
       if not SendBufFully(Peer2,Buf,r) then exit;
     end;
     if FD_ISSET(Peer2.SocketHandle, FDSet) then
     begin
       r:=Peer2.ReceiveBuf(Buf,Length(Buf));
       if r=0 then exit;
       if not SendBufFully(Peer1,Buf,r) then exit;
     end;
   end else
     exit;
 end;
end;