Re: [lwip-users] Recovering from network outage

[address@hidden]

Am 13.04.2021 um 13:31 schrieb Thompson, Jeff:
> Regarding the connection timeout, I tried setting timeout values for the 
> socket immediately after creating it:
>
>       struct timeval sendToVal =
>       {
>               .tv_sec = HTTPS_SOCKET_TIMEOUT,
>               .tv_usec = 0
>       };
>
>       lwip_setsockopt(*(int *)sockFd, SOL_SOCKET, SO_SNDTIMEO, &sendToVal, 
> sizeof(sendToVal) );
>       lwip_setsockopt(*(int *)sockFd, SOL_SOCKET, SO_RCVTIMEO, &sendToVal, 
> sizeof(sendToVal) );

For a starter, check the return value of setsockopt. Maybe you haven't
enabled support for this in lwIP code...

Regards,
Simon

>
> but the call to lwIP_recv does not return after I pull the cable on the 
> network side of my switch and wait for much longer than the timeout value I 
> set.
>
> Jeff Thompson  |  Senior Electrical Engineer-Firmware
> +1 704 752 6513 x1394
> www.invue.com
> -----Original Message-----
> From: lwip-users <lwip-users-bounces+jeffthompson=invue.com@nongnu.org> On 
> Behalf Of goldsimon@gmx.de
> Sent: Tuesday, April 13, 2021 05:17
> To: Mailing list for lwIP users <lwip-users@nongnu.org>
> Subject: Re: [lwip-users] Recovering from network outage
>
> Am 13.04.2021 um 08:08 schrieb Rod Boyce:
>> Jeff,
>>
>> It sounds like you are using Ethernet this being the case you can
>> detect link-up and link-down from the Ethernet PHY.
>>
>> This means that you can poll the Ethernet PHY for link status and
>> either take networking down when Phy is disconnected or bring
>> networking up when Phy is connected.
>
> While you can check if the phy is reconnected (hint: use the link status 
> callback provided by lwIP), this will not be of much use, as you could well 
> get disconnected behind the first (or any) switch (so your own link status 
> always stays up).
>
> In this case, there's really no other option than to poll for a connection 
> and wait for it to succceed. Ideally, you'd combine this with a low-enough 
> (but not too low) connection timeout.
>
> Regards,
> Simon
>
>>
>>
>> Hope that helps.
>>
>> Rod
>>
>>
>> On 12/04/2021 21:03, Thompson, Jeff wrote:
>>>
>>> How can I recover from a network outage? I leave the cable from my
>>> system to the network switch connected, but pull the cable from the
>>> network switch to the cloud. Detecting that the server I was talking
>>> to is no longer talking is easy enough, but how do I recover? I’m
>>> using a plain old socket to make the connection, and
>>> lwIP_send/lwIP_recv) for data transfer of an HTTPS GET request.
>>>
>>>  
>>>
>>> I start up a timer that expires if there is no server response after
>>> a minute; much more than enough, I’m told. But what then? Can the
>>> timer callback do anything to make lwIP_send or lwIP_recv return to
>>> the calling task, preferably with an error?
>>>
>>>  
>>>
>>> *Jeff Thompson* |  Senior Electrical Engineer-Firmware
>>> +1 704 752 6513 x1394
>>> www.invue.com <www.invue.com>
>>>
>>>  
>>>
>>>
>>> _______________________________________________
>>> lwip-users mailing list
>>> lwip-users@nongnu.org
>>> https://lists.nongnu.org/mailman/listinfo/lwip-users
>>
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>
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