Multiple network to the same SSID with d-bus api

[Radoslaw Martyniszyn]

Hi Dan,

Thank you very much for your answer.

The best solution for me would be not to select any specific network
and let the supplicant auto-select one for me. I tried a few
approaches but did not observe auto-select so far.
- If I don't select any network (not calling SelectNetwork) then
networks Enabled property is false and no connection is performed.
- I tried to call SelectNetwork with passing null as parameters (I use
GDbusProxy) and got GDBus.Error:org.freedesktop.DBus.Error.InvalidArgs
- I tried to specify empty string as object (o), but GDbusProxy did
not allow for that
- I tried to specify "/" as object but got InvalidArgs error.
>From code analysis it seems to me function
wpas_dbus_handler_select_network do not allow empty network:

if (iface == NULL || net_id == NULL || !wpa_s->dbus_new_path ||
        os_strcmp(iface, wpa_s->dbus_new_path) != 0) {
        reply = wpas_dbus_error_invalid_args(message, op);
        goto out;
    }

So far I implemented the following solution:
- Create a few networks (addNetwork) with priority
- Select a network with the highest priority (selectNetwork)
- Enable all other networks by changing Enabled property of
fi.w1.wpa_supplicant1.Network to true.
Handling "priority" property works fine. In above solution I am a bit
worried because function wpa_supplicant_select_network has a comment
"Mark all other networks disabled or mark all networks enabled if no
network specified", so I guess there might be some racing conditions.

BR,
Radek

On Wed, Jun 21, 2017 at 5:40 PM, Dan Williams <dcbw at redhat.com> wrote:
> On Mon, 2017-06-12 at 23:14 +0200, Radoslaw Martyniszyn wrote:
>> Hello,
>>
>> In my application I would like to connect to a predefined AP 1
>> (BSSID+SSID) or select any AP 2 with the same SSID in case default AP
>> 1
>> disappears or I cannot connect to it. I believe that could be
>> achieved
>> by the following config:
>>
>> network={
>>   ssid="theSameSSID"
>>   bssid=00:11:22:33:44:55
>>   psk="theSamePSK"
>>   priority=1
>> }
>>
>> network={
>>   ssid="theSameSSID"
>>   psk="theSamePSK"
>>   priority=0
>> }
>>
>> Could I use wpa_supplicant d-bus API to achieve above functionality?
>>
>> I think I could achieve above functionality creating two instances of
>> network fi.w1.wpa_supplicant1.Interface.AddNetwork. Network1 would
>> contain SSID, BSSID, priority=1 while Network2 would
>> contain SSID, priority=0. Next I would call
>> fi.w1.wpa_supplicant1.Interface.SelectNetwork on Network1. Does my
>> plan make any sense? Should wpa_supplicant connect to Network2
>> automatically if there is no AP1? My initial test showed that
>> wpa_supplicant do not connect to AP2 in case I turn off AP1, but I
>> need to check that more deeply.
>
> Yes, this is how it works.  You call AddNetwork and in response you
> will get a unique D-Bus Object Path that represents the network.  The
> Object Path is what you pass to the SelectNetwork and that allows you
> to uniquely specify the network even if they have the same SSID.
>
> If you do not select a specific network, the supplicant will auto-
> select one for you.  It should respect the "priority" property.  But if
> it's not, getting the "-dddt" output from the supplicant would be
> useful.
>
> Dan