Hello
I need help to understand the basic concept of UDP sockets:
I am trying to set up a point-to-point connection between host
A(192.168.2.222:4000) and host B(192.168.2.224:4000)
I am opening the socket like this:
------------------------------------------------------------------
function UDP_trx.s_open(IP,PORT:string):boolean;
begin
udpsock:=TUDPBlockSocket.Create;
udpsock.Bind('0.0.0.0',PORT); // bind socket to local NIC ?
udpsock.Connect(IP,PORT); // connect socket to remote IP:PORT ?
end;
-----------------------------------------------------------------
I am sending one byte over the socket (do I need to connect for every
SendByte?)
-----------------------------------------------------------------
procedure UDP_trx.s_tx(txbyte:byte; IP,PORT:string);
var i:integer; s:string;
begin
//udpsock.Connect(IP,PORT); // do I need to reconnect every time?
udpsock.SendByte(txbyte);
end;
-----------------------------------------------------------------
And I am receiving one byte over the socket like this:
-----------------------------------------------------------------
function UDP_trx.s_rx(var rxbyte:byte; IP,UDPPRT:string):boolean;
var ipstr:string; prt:integer;
begin
if udpsock.WaitingDataEx=0 then begin result:=false; exit; end;
rxbyte:=udpsock.RecvByte(1);
//ipstr:=udpsock.GetRemoteSinIP;
//prt:=udpsock.GetRemoteSinPort;
//if (ipstr=IP) and (prt=StrToInt(UDPPRT)) then begin result:=true;
exit; end; //filter for RemoteSin
result:=true;
end;
-----------------------------------------------------------------
What I do not understand is this:
Whenever I send a byte to any IP adress (even one that does not exist) I am
receiving a byte at the remote end as long as the port is matching.
Only when I use the s_rx filter with GetRemoteSinIP and GetRemoteSinPort I
can be sure that I receive from the correct source IP.
So I suppose that I have not really understood how to use BIND and CONNECT
Thank you for help
Mit freundlichem Gruß / Yours sincerely / Cordialement
Christian Sporer
Grüntenstr.18
80686 München
Tel.: +(49) 89 54217952
Fax.: +(49) 89 52389119
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