topic Re: Unexpected behavior with RTCS_selectset() and accept() for TCP server socket in MQX Software Solutions

Unexpected behavior with RTCS_selectset() and accept() for TCP server socket

tmeyer — Thu, 29 Oct 2020 08:50:06 GMT

Hi all.

I am running a Kinetis K60 Tower.

I have a simple TCP server setup to listen for incoming client connections. I am able to detect (with RTCS_selectset) and accept incoming client connections as expected for a few connections (say 10-15) . Then randomly upon attempting to connect to the server, the listening sever socket enters a state where RTCS_selectset() will immediately return indicating there is a client ready, accept return immediately with return code RTCS_SOCKET_ERROR. However when calling RTCS_geterror(server_socket) I get RTCS_OK. It is like select says a client is waiting to connect, and accept is trying but failing to accpet the connection - but not providing an error.

Furthermore when this state is entered, even shutting down and and creating a new server socket continue to behave this way.

Any suggestions?

Thanks

Tim

while(retry){client_socket = RTCS_selectset(&server_socket, 1, BSP_ETHERNET_CONNECTION_TIMEOUT);  if(client_socket == RTCS_SOCKET_ERROR)   {      break;  }   else if(client_socket == server_socket)   {   client_socket = accept(server_socket, NULL, NULL);    if(client_socket == RTCS_SOCKET_ERROR)    {    int status = RTCS_geterror(server_socket);    if (status == RTCS_OK)     {     /// keeps ending up here when in bad state    }....

Re: Unexpected behavior with RTCS_selectset() and accept() for TCP server socket

MPotts — Sat, 31 Mar 2012 01:40:17 GMT

Hi Tim,

I'm afraid this is not advice, just a report of somewhat similar behavior. I am also running a simple socket server that runs ok for a while and then fails. In my case calls to RTCS_selectset on a listening socket that was working no longer signal when a connection is being attempted.

        while (!resetip)
       {
           rc = RTCS_selectset(&sock, 1, 1000);
           if (rc == RTCS_SOCKET_ERROR) { err = "RTCS_selectset"; goto error; }
           if (rc == 0) { continue; }

           /* Accept connection */
           insock = accept(sock, &inaddr, &inaddr_len);

Mark

Re: Unexpected behavior with RTCS_selectset() and accept() for TCP server socket

edgarsevilla — Wed, 12 Sep 2012 22:37:56 GMT

Happens to me as well when I try to make a second connection to the same server

Any Ideas??

Thanks

Edgar Sevilla

Re: Unexpected behavior with RTCS_selectset() and accept() for TCP server socket

Luis_Garabo — Thu, 13 Sep 2012 15:52:40 GMT

Hi Tim,

Sometimes it is necessary to release the sockets from connections that were closed. It happened to me that I wasn't closing the sockets of clients that were leaving the server and the resources weren't been released by MQX in a big period of time and then there were no more resources to create new sockets for the new incomming connections.

Are you closing the sockets in the server side once the client left the connection?

I hope this helps.

Garabo

Re: Unexpected behavior with RTCS_selectset() and accept() for TCP server socket

MPotts — Mon, 08 Oct 2012 22:09:28 GMT

I found the problem to be using

shutdown(sock, FLAG_CLOSE_TX);

which does not release the internal socket context for four minutes. Using

shutdown(sock, FLAG_ABORT_CONNECTION);

released the socket context immediately and accepted another connection.

Mark

Re: Unexpected behavior with RTCS_selectset() and accept() for TCP server socket

Luis_Garabo — Thu, 11 Oct 2012 20:25:24 GMT

It is good you foind the solution! Congrats!

Re: Unexpected behavior with RTCS_selectset() and accept() for TCP server socket

netra — Tue, 20 Nov 2012 15:38:51 GMT

Hi,

Can anyone tell how to know , whether socket is shutdown or not??

after shutting down the socket , still i am unable to create to create socket again.

It throwing error in bind().

Plz reply

Thanks,

Netra