Re: [lwip-users] Patch for bug 23119

[Ken Smith]

On Wed, Mar 11, 2009 at 1:50 AM, Kieran Mansley <address@hidden> wrote:
> On Tue, 2009-03-10 at 14:22 -0700, Ken Smith wrote:
>> I'm using lwip-1.3.0 and I believe I have encountered the problem
>> discussed here.
>>
>> http://savannah.nongnu.org/bugs/?23119
>>
>> I am using SO_RCVTIMEO (set to 30 seconds) and occasionally, my
>> application gets into a loop where lwip with TCP_DEBUG enabled just
>> keeps displaying:
>>
>> tcp_slowtmr: processing active pcb
>> tcp_slowtmr: max SYN retries reached
>> tcp_pcb_purge
>> tcp_pcb_purge: data left on ->unacked
>
> Sounds like you have a different problem to the bug you mention: that
> one was just to do with whether timeouts were classed as fatal or not.
> I therefore think that the patch won't help.
>
> The output above suggests that lwIP has tried to open a connection to
> another host but has received no reply after a lot of attempts, and so
> is giving up.  When removing the connection it noticed that there is
> some data on the unacked queue, which is a little odd for a connection
> that has not yet been opened, but it should cope with that, free the
> unacked queue, and remove the connection.
>
> Can you explain more about how your application uses the sockets API?
> Maybe with a code sample to show what it's doing when things go wrong.
> A packet capture can often be useful too.

I'm using the lwIP sockets API via axTLS under FreeRTOS on ARM7.
Here's my call to connect.

struct sockaddr_in client_addr;
int client_fd = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
int32_t recv_timeout = 30000; //required to be in millis
setsockopt(client_fd,SOL_SOCKET,SO_RCVTIMEO, (char*)&recv_timeout,
sizeof(recv_timeout));

AxsslLog(CioVerLow, "**tls: SERVER: trying to connect\r\n");
if (lwip_connect(client_fd, (struct sockaddr *) &client_addr,
sizeof(client_addr)) < 0) {
  AxsslLog(CioVerLow, "**tls: SERVER: connect failed\r\n");
  lwip_close(client_fd)
  ssl_ctx_free(ssl_ctx);
  return NULL;
}

The ethernet port of my device is connected to a layer two bridge and
then to an ethernet->CDMA/EVDO modem.  (In the wild, it is connected
directly to the modem.)  When I do tcpdump on the bridge, I get no
output from my device.  It thinks it's trying to get out to the
network but no packets are actually coming out.

I've attached two versions of my lwipopts.h file and output from a
call to stats_display().  The lwipopts.h that was in play at the time
was lwipopts.h.cal2.  Here is the error output that keeps looping when
lwip is in trying to connect.

  1 lwip_socket(PF_INET, SOCK_STREAM, 6) = 0
  2 **tls: SERVER: trying to connect
  3 lwip_connect(0, addr=OMITTED port=OMITTED)
  4 tcp_connect to port OMITTED
  5 tcp_slowtmr: processing active pcb
  6 tcp_slowtmr: processing active pcb
  7 tcp_slowtmr: processing active pcb
  8 tcp_slowtmr: processing active pcb
  9 tcp_slowtmr: polling application
 10 tcp_slowtmr: processing active pcb
 11 tcp_slowtmr: processing active pcb
 12 tcp_slowtmr: processing active pcb
 13 tcp_slowtmr: processing active pcb
 14 tcp_slowtmr: polling application
 15 tcp_slowtmr: processing active pcb
 16 tcp_slowtmr: processing active pcb
 17 tcp_slowtmr: processing active pcb
 18 tcp_slowtmr: processing active pcb
 19 tcp_slowtmr: polling application
 20 tcp_slowtmr: processing active pcb
 21 tcp_slowtmr: processing active pcb
 22 tcp_slowtmr: processing active pcb
 23 tcp_slowtmr: processing active pcb
 24 tcp_slowtmr: polling application
 25 tcp_slowtmr: processing active pcb
 26 tcp_slowtmr: processing active pcb
 27 tcp_slowtmr: processing active pcb
 28 tcp_slowtmr: processing active pcb
 29 tcp_slowtmr: polling application
 30 tcp_slowtmr: processing active pcb
 31 tcp_slowtmr: processing active pcb
 32 tcp_slowtmr: processing active pcb
 33 tcp_slowtmr: processing active pcb
 34 tcp_slowtmr: polling application
 35 tcp_slowtmr: processing active pcb
 36 tcp_slowtmr: processing active pcb
 37 tcp_slowtmr: processing active pcb
 38 tcp_slowtmr: processing active pcb
 39 tcp_slowtmr: polling application
 40 tcp_slowtmr: processing active pcb
 41 tcp_slowtmr: processing active pcb
 42 tcp_slowtmr: processing active pcb
 43 tcp_slowtmr: processing active pcb
 44 tcp_slowtmr: polling application
 45 tcp_slowtmr: processing active pcb
 46 tcp_slowtmr: processing active pcb
 47 tcp_slowtmr: processing active pcb
 48 tcp_slowtmr: processing active pcb
 49 tcp_slowtmr: polling application
 50 tcp_slowtmr: processing active pcb
 51 tcp_slowtmr: max SYN retries reached
 52 tcp_pcb_purge
 53 tcp_pcb_purge: data left on ->unacked
 54 lwip_connect(0) failed, err=-5
 55 **tls: SERVER: connect failed
 56 lwip_close(0)

Any ideas appreciated.

    Thanks,
    Ken

lwipopts.h
Description: Binary data

lwipopts.h.cal2
Description: Binary data

stats_display
Description: Binary data