Re: nm_setting_gsm_get_pin() retuns null

[Dan Williams <dcbw redhat com>]

On Wed, 2011-10-05 at 22:12 +0200, Anders Feder wrote:
> Thanks for that thorough explanation. However, I wonder if there isn't a 
> race condition in that implementation: if we request all three 
> properties in gsm_device_added(), can we be certain that we have all of 
> them once we are in sim_id_reply()? Isn't there a risk that 
> sim_id_reply() might be called back before unlock_reply()?

Yes, a small risk.  This can be alleviated by doing some logic in both
functions and tracking in the 'info' struct whether we've gotten replies
for both the initial modem properties and the initial card properties,
and then only doing the unlock dialog when both of those are true AND
the other stuff I wrote was true, and doing that check from both places.
It just means more variables.

Dan

> Anders Feder
> 
> On 03-10-2011 23:18, Dan Williams wrote:
> > On Mon, 2011-10-03 at 14:20 +0200, Anders Feder wrote:
> >> Where would you propose the new code be added?
> >>
> >> In the first iteration, I imagine it would work something like this:
> >>
> >> If (UnlockRequired)
> >>       Get SimIdentifier
> >>       If (SimIdentifier is found)
> >>           Get PIN for SimIdentifier from keyring
> >>           If (PIN is found for SimIdentifier)
> >>               Try unlock using saved PIN
> >>               While (unlock failed)
> >>                   Prompt user for new PIN
> >>                   Try unlock using new PIN
> >>                   If (unlock succeeded)
> >>                       Save new PIN for SimIdentifier to keyring
> >>
> >> If this works, a similar procedure could be applied for
> >> DeviceIdentifier, if SimIdentifier is not found.
> >>
> >> Is this the best approach?
> > Yeah, that's basically it.  So UnlockRequired and DeviceIdentifier are
> > both properties of the org.freedesktop.ModemManager.Modem interface, and
> > thus you can retrieve them both in the same D-Bus properties call using
> > GetAll().  For that, in src/applet-device-gsm.c's gsm_device_added()
> > function, where it calls the Get() method with UnlockRequired, what you
> > want to do is call "GetAll" instead and kill the "UnlockRequired"
> > argument.  Then in the unlock_reply() for the dbus_g_proxy_end_call()
> > you'll do something like:
> >
> > GHashTable *props = NULL;
> >
> > if (dbus_g_proxy_end_call (proxy, call,&error,
> >                             DBUS_TYPE_G_MAP_OF_VARIANT,&props,
> >                             G_TYPE_INVALID)) {
> >      GHashTableIter iter;
> >      const char *prop_name;
> >      GValue *value;
> >
> >      g_hash_table_iter_init (&iter, props);
> >      while (g_hash_table_iter_next (&iter, (gpointer)&prop_name, (gpointer)&value)) {
> >          if ((strcmp (prop_name, "UnlockRequired") == 0)&&  G_VALUE_HOLDS_STRING (value)) {
> > 	    g_free (info->unlock_required);
> >              info->unlock_required = parse_unlock_required (value);
> >          }
> >
> >          if ((strcmp (prop_name, "DeviceIdentifier") == 0)&&  G_VALUE_HOLDS_STRING (value)) {
> >              g_free (info->devid);
> >              info->devid = g_value_dup_string (value);
> >          }
> >      }
> > }
> >
> > That takes care of the UnlockRequired and DeviceIdentifier properties.
> > Now you need to get the SimIdentifier property, which is a GSM-specific
> > property (unlike UnlockRequired and DeviceIdentifier which are provided
> > for CDMA devices too).  For that you'll want to do something like this
> > in gsm_device_added():
> >
> > 	dbus_g_proxy_begin_call (info->props_proxy, "Get",
> > 	                         sim_id_reply, info, NULL,
> > 	                         G_TYPE_STRING, MM_DBUS_INTERFACE_MODEM_GSM_CARD,
> > 	                         G_TYPE_STRING, "SimIdentifier",
> > 	                         G_TYPE_INVALID);
> >
> > and then basically copy&  paste the current unlock_reply() function as
> > sim_id_reply(), fix up the property stuff there (obviously you're
> > handling the SimIdentifier property instead of UnlockRequired) and then
> > at the end of that function, you want something like this:
> >
> >      if (info->unlock_required&&  (info->simid || info->devid))
> > 	unlock_dialog_new (info->device, info);
> >
> > which will actually do the unlock.  You dont' want to call
> > unlock_dialog_new() in unlock_reply() because you don't have the
> > SimIdentifier yet.
> >
> > Then unlock_dialog_new() is where you'd query the keyring for existing
> > PINs using SimIdentifier as one of the attributes the PIN would be
> > stored with (using gnome_keyring_find_itemsv_sync()) and if there wasn't
> > any result try again with DeviceIdentifier.  Check out utils/utils.c and
> > src/applet-agent.c for more examples of how to write and read items from
> > the keyring.
> >
> > Dan
> >
> >> Anders Feder
> >>
> >> On 03-10-2011 06:00, Dan Williams wrote:
> >>> On Sat, 2011-10-01 at 02:41 +0200, Anders Feder wrote:
> >>>> Thanks. I've left you a question in the bug report. I may be
> >>>> interested in taking a stab at this if it isn't overwhelmingly
> >>>> difficult.
> >>> Responded.  It shouldn't be too difficult; there's already code there to
> >>> track the modem object from ModemManager and do the right thing.  So in
> >>> addition to the UnlockRequired property, you'd also want to grab and
> >>> watch the SimIdentifier and DeviceIdentifier properties, and use those
> >>> to look in the keyring for the right PIN.
> >>>
> >>> Dan
> >>>
> >>>> Anders Feder
> >>>>
> >>>> On 30-09-2011 07:31, Dan Williams wrote:
> >>>>> On Wed, 2011-09-21 at 08:34 +0200, Anders Feder wrote:
> >>>>>> Hi,
> >>>>>>
> >>>>>> I'm trying to write a fix for this bug. I've been experimenting with
> >>>>>> testing whether a given connection is configured to autoconnect, using
> >>>>>> this code (inside applet-device-gsm.c):
> >>>>>>           NMSettingConnection *setting =
> >>>>>>           nm_connection_get_setting_connection (connection);
> >>>>>>           NMSettingGsm *setting_gsm = nm_connection_get_setting_gsm
> >>>>>>           (connection);
> >>>>>>           if ((autoconnects = autoconnects ||
> >>>>>>           (nm_setting_connection_get_autoconnect (setting)&&
> >>>>>>           nm_setting_gsm_get_pin (setting_gsm))))
> >>>>>>               break;
> >>>>>> However, nm_setting_gsm_get_pin (setting_gsm) seems to always return
> >>>>>> null, even when a PIN is set for the connection. Can someone pelase
> >>>>>> tell me why this might be? Under what circumstances may this function
> >>>>>> return null even when a PIN is set?
> >>>>> PIN codes in the connection data are deprecated because PINs are
> >>>>> specific to the SIM card, not to the connection.  If you lose your SIM
> >>>>> and get another from the same provider, the PIN will be different, and
> >>>>> the PIN in the connection data will be wrong.  I've written up some
> >>>>> notes on what I think should be done in the GNOME bug report for this
> >>>>> issue:
> >>>>>
> >>>>> https://bugzilla.gnome.org/show_bug.cgi?id=618532
> >>>>>
> >>>>> Happy to help if there are more questions.
> >>>>>
> >>>>> Dan
> >>>>>
> >>>>>
> >>>>>
> >>>>>
> >>>
> >
> >
>