Re: NIST time server - TCPIP problem

On 6/26/2014 7:48 PM, Roger Hunt [email protected] [rabbit-semi] wrote:
> Hi Scott,
>
> Thank you for the prompt reply.  I checked the Dynamic C TCP/IP
> manual, which says the MAX_SOCKETS define has been deprecated.  I did
> not have a value defined for MAX_TCP_SOCKET_BUFFERS, so was hoping you
> had nailed the problem.  Since the default value is 4, I added the line:
>    #define MAX_TCP_SOCKET_BUFFERS 8
> and when that did not work, made it 16.  That did not work either.
>
> The code which is failing is:
>
>     printf("\nConnecting with NIST server ...\n");
>     sock_init();
>     while (ifpending(IF_DEFAULT) == IF_COMING_UP)
>     {
>         tcp_tick(NULL);
>     }
>     ip=resolve(NIST_SERVER_IP);
>     tcp_open(&s, 0, ip, NIST_PORT, NULL);
>     sock_wait_established(&s, NIST_TIMEOUT, NULL, &status);
>     sock_mode(&s, TCP_MODE_ASCII);
>     // Receive and process data -- the server will close the connection,
>     // which will cause execution to continue at sock_err below.
>     while (tcp_tick(&s))
>     {
>         sock_wait_input(&s, NIST_TIMEOUT, NULL, &status);
>         sock_gets(&s, buffer, 48);
>     }
>
>     sock_err:
>     if (status == -1)
>     {
>         printf("\nConnection timed out, exiting.\n");
>         exit(1);
>     }
>
> I get the "Connection timed out, exiting" message almost instantly,
> which means the sock_wait_input function is returning a status of -1,
> which according to the DC manual "indicates a reset or abort."  This
> same code works if I haven't opened the http handler first.
>
> Scott, I know absolutely nothing about TCP/IP stuff, and am really
> struggling here.  I am embarrassed to admit that I have already spent
> a couple of days on this issue.  Do you have any other ideas?
>
> Thanks so much,

Make sure you define MAX_TCP_SOCKET_BUFFERS before you #use any libraries.

The while loop with sock_wait_input() will kill the http server while it
waits for data. Any time you have something waiting, you need to poll
for data and if none ready call tcp_tick(NULL) and http_handler();

It will work as is, but the http server wil be unresponsive while it
waits. The same applies to sock_wait_established().



-- 
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     Scott G. Henion, Consultant
Web site:    http://SHDesigns.org
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