[PATCH] sim-qmi: load operator identifier and name from NAS home network

[Dan Williams]

On Thu, 2015-10-22 at 23:30 +0200, Aleksander Morgado wrote:
> On Thu, Oct 22, 2015 at 10:45 PM, Dan Williams <dcbw at redhat.com> wrote:
> >> Being NAS commands, are these available also when not registered
> >> anywhere? E.g. when in low-power mode?
> >> I've seen people using these commands to retrieve SIM MCCMNC, but was
> >> never sure about them as they were NAS and not DMS.
> >
> > Tried Gobi 1k and UML290; they both still return the home network when
> > in low-power mode.  Also, the Gobi 1k didn't have any antennas connected
> > and it still returned the right home network...
> 
> Ah! good then.
> 
> The issue with the MNC length (whether 2 or 3 digits) still affects
> this implementation though. Actually, the implementation would not be
> ok even for 2 digits, as it's not appending a leading 0 for
> single-digit MNCs (e.g. "2141" instead of "21401"):
>     operator_id = g_strdup_printf ("%" G_GUINT16_FORMAT "%"
> G_GUINT16_FORMAT, mcc, mnc);
> It should append leading 0s to the MNC based on whether the MNC is 2
> or 3 digit long.

Ah, good point.  I'd copied that from qmicli code and I guess it's wrong
there, and I didn't catch it here either.

> Now, there's a TLV 0x12 "3GPP Home Network MNC" in Get Home Network
> that we didn't add yet to libqmi as far as I can tell. It consists of
> a sequence of 2 bytes that are read as booleans:
>   * 1st byte: whether the network is 3GPP.
>   * 2nd byte: if 1st byte is true (net is 3GPP), whether the MNC is 3
> digits long.
> 
> Based on this, we could do:
>   * If TLV 0x12 is available,  we already got told the MNC length and
> we know how many 0s we need to prepend.
>   * If TLV 0x12 is not available, we only print 3 digits if MNC is >99
> and otherwise 2 digits always.
> This logic is already what we do when building MCCMNC from current
> serving system, as in common_process_serving_system_3gpp().

Works for me, would you mind taking a stab at this?  I have to move on
to other stuff tomorrow and early next week...

Dan