Need Clarification on DCS handling in Status Report for SMS

Need Clarification on DCS handling in Status Report for SMS

[Sankar]

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Hi,

While doing a code reading for ofono SMS, it is observed that there seems to
be an issue with the way DCS is handled for SMS status report notify.

In the decode SMS function, there is a check to find out if there is a PI
(parameter identifier). If there is a PI and no DCS flag set, then the ofono
core sets the dcs to default. If the PI itself is missing in the PDU
received from the network, then the dcs values are not set to default.

This seems to cause a problem, where, the decoding of dcs fails, and results
in not sending the delivery notification to clients.

Can some one please comment on this.

Thanks,
Sankar.

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RE: Need Clarification on DCS handling in Status Report for SMS

[Rajesh.Nagaiah]

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Hi Sankar,

> In the decode SMS function, there is a check to find out if 
> there is a PI (parameter identifier). If there is a PI and no 
> DCS flag set, then the ofono core sets the dcs to default. If 
> the PI itself is missing in the PDU received from the 
> network, then the dcs values are not set to default.
> 
> This seems to cause a problem, where, the decoding of dcs 
> fails, and results in not sending the delivery notification 
> to clients.

Yes, this is a bug. But rather than setting the DCS to default in
this case, we should rather not call that sms_dcs_decode() function
from ofono_sms_status_notify(), as the class information derived from
the DCS decoding is not used there and also we are not handling the
optional text information in the status report handling currently.

If we decide to handle this optional text information (most likely not
going to happen), then some modifications are required.

Also there is another bug in the current code which might not be
relevant
if we decide to remove the sms_dcs_decode() function call from
ofono_sms_status_notify(). In that function call instead of passing
s.status_report.dcs, we are currently passing s.deliver.dcs.

BR,
Rajesh

Re: Need Clarification on DCS handling in Status Report for SMS

[Sankar]

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Hi Rajesh,


On Thu, Dec 2, 2010 at 7:33 AM, <Rajesh.Nagaiah@elektrobit.com> wrote:

> Hi Sankar,
>
> > In the decode SMS function, there is a check to find out if
> > there is a PI (parameter identifier). If there is a PI and no
> > DCS flag set, then the ofono core sets the dcs to default. If
> > the PI itself is missing in the PDU received from the
> > network, then the dcs values are not set to default.
> >
> > This seems to cause a problem, where, the decoding of dcs
> > fails, and results in not sending the delivery notification
> > to clients.
>
> Yes, this is a bug. But rather than setting the DCS to default in
> this case, we should rather not call that sms_dcs_decode() function
> from ofono_sms_status_notify(), as the class information derived from
> the DCS decoding is not used there and also we are not handling the
> optional text information in the status report handling currently.
>
> If we decide to handle this optional text information (most likely not
> going to happen), then some modifications are required.
>
> Also there is another bug in the current code which might not be
> relevant
> if we decide to remove the sms_dcs_decode() function call from
> ofono_sms_status_notify(). In that function call instead of passing
> s.status_report.dcs, we are currently passing s.deliver.dcs.
>

Thanks for your inputs. Can you please let me know when this will be
addressed in the ofono.

>
> BR,
> Rajesh
> _______________________________________________
> ofono mailing list
> ofono(a)ofono.org
> http://lists.ofono.org/listinfo/ofono
>

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Re: Need Clarification on DCS handling in Status Report for SMS

[Denis Kenzior]

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Hi Rajesh,

> 
> Yes, this is a bug. But rather than setting the DCS to default in
> this case, we should rather not call that sms_dcs_decode() function
> from ofono_sms_status_notify(), as the class information derived from
> the DCS decoding is not used there and also we are not handling the
> optional text information in the status report handling currently.

It is still a bug that should be fixed ;)

> 
> If we decide to handle this optional text information (most likely not
> going to happen), then some modifications are required.
> 
> Also there is another bug in the current code which might not be
> relevant
> if we decide to remove the sms_dcs_decode() function call from
> ofono_sms_status_notify(). In that function call instead of passing
> s.status_report.dcs, we are currently passing s.deliver.dcs.

That is a good catch.  We should actually check the DCS to filter out
any malformed status reports.

Anyway, both issues should now be fixed with commits:
c5a42cfabe3abe0d99299daffbe04c33a217fb25
ac72349017fbfdecbba000c0259cc6b99f0873ed

Please test and report back whether the issues persist.

Regards,
-Denis