Mbed-os: UBLOX cellular: missing a callback on socket closed

[pilotak]

Description

as per conversation #10687

Once you are succesfully connected to server and server stops working you can see in debug:

[DBG ][CELL]: AT OoB readable 1, len 0
[INFO][CELL]: AT RX (14): <cr><ln>+UUSOCL: 0<cr><ln>
[DBG ][CELL]: AT OoB done

which is perfect but i have callback registered with _socket.sigio(callback(this, &Test::socketCb)); and there is no cb called. If I try to listen for data _socket.recv(buffer, size) after i received above, no negative error is returned so it looks the socket is still open (from OS point of view).
The only way to check if the socket is still open is to write data to it _socket.send(data, size) - this will give you NSAPI_ERROR_DEVICE_ERROR (-3012)

The problem is that UBLOX_AT_CellularStack doesn't have a callback/not acting for this command received.

Issue request type

[ ] Question
[ ] Enhancement
[x] Bug

[ciarmcom]

Internal Jira reference: https://jira.arm.com/browse/MBOCUSTRIA-1262

[0xc0170]

cc @ARMmbed/mbed-os-wan

[0xc0170]

@ARMmbed/team-ublox

[fahim-ublox]

Internal jira reference : PGM_NO_MBD-239

[mudassar-ublox]

Updated callback for socket close. @pilotak can you please check it works fine now or anything else required.
https://github.com/ARMmbed/mbed-os/pull/10811

[pilotak]

Thanks @mudassar-ublox it now works as expected

[pilotak]

just a question though, i noticed that cb is only called on disconnect ie manual or now remote close. Is that the intended behaviour? or is there a chance it can be called on some other event? so i know i can treat it like that

[mudassar-ublox]

Callback is also called on +UUSORD and +UUSORF.

[pilotak]

ok and how would i get a reason why cb was called? sigio doesn't pass any argument

[bqam-ublox]

To differentiate between what triggered the cb, you will need to keep a check on rx_avail and closed parameters from the CellularSocket class. @mudassar-ublox will shortly generate another PR to update these parameters.

[mudassar-ublox]

Updated socket flags.
10840

[pilotak]

thanks a lot ublox team, i hope that both PR will be merged shortly

[pilotak]

@bqam-ublox @mudassar-ublox could i kindly ask you to show me an example how to retreive rx_avail and closed?

// TCPSocket _socket;

void Test::socketCb() {
    debug("socket change\n");
   // some magic here
}

void Test::connect(){
   ...
   _socket.sigio(callback(this, &Test::socketCb));
}

[bqam-ublox]

@pilotak the AT_CellularStack class is using these parameters, have a look here: https://github.com/ARMmbed/mbed-os/blob/master/features/cellular/framework/AT/AT_CellularStack.cpp#L252
Not sure how you can use them in your application. Could you please create a new issue on mbed with more details. The ARM guys might help to figure out if there is already any example or test case present. Thanks

[pilotak]

will do thanks