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winexec · Guest

Hi all.

I'm trying to understand how the winsock is working and I encounter a problem: the socket is listening OK but afterwards cannot be closed! I dont't know what could be wrong.

Here is a sample:

procedure Listen_Close;
var
wsadata:twsadata;sock:integer;
addr:tsockaddrin;
begin
wsastartup(MAKEWORD(1,1),wsadata);
sock:=socket(AF_INET,SOCK_STREAM,IPPROTO_TCP);
addr.sin_family:=AF_INET;
addr.sin_addr.s_addr:=htonl(INADDR_ANY);
addr.sin_port:=htons(12345);//a port
bind(Sock,addr,sizeof(addr))
WSAAsyncSelect(Sock,aHandle,aMsg,FD_ACCEPT or FD_READ or FD_CLOSE);
listen(Sock,2);//not sure about that 2

//Now I want to close the socket

shutdown(sock,2);
closesocket(sock);
wsacleanup;
end;

Thx for help.

Francois PIETTE · Guest

If you use async sockets, then you must wait for the events to occur !
A listening socket doesn't have to be shutdown, just call closesocket.

btw: You can download ICS (http://www.overbyte.be) and see wsocket.pas
source file. It make use of asynchronous socket. You could learna lot
studying ICS source code.

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Andy M. · Guest

winexec · Guest

Thx, I downloaded ICS and I'll take a look later.

I also made more research. I understand now that TCP is a bidirectional protocol and for closing a socket must be send a Socket.Close command from the Client. In my case it seems that the socket is not closing properly. What I did was that: I made the server listen, I connected to the server and all was OK, I closed the connection from the client, the server received the message (FD_CLOSE) and started the closing and both Shutdown and CloseSocket functions return -1. So there is a bug! Can you explain me how the socket can be close normally? Thx.

"Francois PIETTE" <francois.piette (AT) overbyte (DOT) be> wrote:

Francois Piette · Guest