Re: [lwip-users] LWIP 1.3.2 and PPP

[Simon Goldschmidt]

The fatal errors have changed in CVS after 1.3.2: ERR_TIMEOUT is not a fatal 
error any more.

Simon


"Sirjee Rooplall" wrote:
> An: "Mailing list for lwIP users" <address@hidden>
> Betreff: [lwip-users] LWIP 1.3.2 and PPP

> Hi as stated above I am using LWIP 1.3.2 and the PPP stack.
> 
> I use the follwoing API's.
> netconn_new
> netconn_connect
> netconn_delete
> netconn_recv - This is called from a freeRTOS task every 10ms, to check if
> any data has arrived.
> netbuf_data
> 
> I have LWIP_SO_RCVTIMEO defined as 1.
> 
> I am using PPP over serial through modem to sever.
> 
> Before I call nettcon_recv to check for data I set a receive timeout:
> pxSeverConnectionHandle->recv_timeout = 10000;   // wait for incoming
> message 10seconds max.
> 
> Now here is the problem.
> 
> Everything works fine provided the server replies within the 10 seconds.
> If netconn_recv timeout, it sets the conn->err to conn->err = ERR_TIMEOUT;
> //  which is -13 and referred to FATAL error.
> 
> The next time netconn_recev is called it encounter this piece of code
> which says:
> if (ERR_IS_FATAL(conn->err)) {
>     return NULL;
>   }
> 
> because the conn->err is set to -13 which is fatal error, netconn_recv
> always returns without checking the mailbox for a message which may take more
> than 10 seconds to come.
> 
> Now the reason I am using the receive timeout in netconn_recv is because
> previously it wait forever for a message and if the message does not come,
> after 20 seconds I close the socket in another Task, and that caused my
> system to crash because netconn_recv was pending on that socket handle.
> 
> In this system using PPP and modem + GPRS it is possible that a message
> may not arrive, and retries are implemented etc to cater for this.
> 
> My question is How do I work around this ERR_IS_FATAL condition, without
> breaking any LWIP rules?
> 
> 
> Kind Regards,
> 
> 
> Sirjee Rooplall
> Figment Design laboratories (Pty) Ltd
> mailto: address@hidden
> Mobile: +27 (0)83 230 8466

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