[PATCH] wifi: Choose a random channel when opening an ap

[PATCH] wifi: Choose a random channel when opening an ap

[Vivien Henriet]

When the tethering mode is started, a WiFi ap is created using the fixed
channel 1 (2412 MHz). There is no way to configure this channel.

This patch make connman choose a random channel every time the ap is created.
---
 plugins/wifi.c | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/plugins/wifi.c b/plugins/wifi.c
index 578b4be7..936f1750 100644
--- a/plugins/wifi.c
+++ b/plugins/wifi.c
@@ -3344,11 +3344,19 @@ static GSupplicantSSID *ssid_ap_init(const char *ssid, const char *passphrase)
 	if (!ap)
 		return NULL;
 
+	/**
+	 * Choose a random channel in the range 1-11. Channels 12-14 are not
+	 * available worlwide.
+	 * Channels within this range are spaced 5 MHz apart from each other.
+	 */
+	int channel = (rand() % 11) + 1;
+	int freq = 2407 + channel * 5;
+
 	ap->mode = G_SUPPLICANT_MODE_MASTER;
 	ap->ssid = ssid;
 	ap->ssid_len = strlen(ssid);
 	ap->scan_ssid = 0;
-	ap->freq = 2412;
+	ap->freq = freq;
 
 	if (!passphrase || strlen(passphrase) == 0) {
 		ap->security = G_SUPPLICANT_SECURITY_NONE;
-- 
2.32.0

Re: [PATCH] wifi: Choose a random channel when opening an ap

[HENRIET Vivien]

Hi Daniel,

Could you have a look to this patch?

I would like to be able to open the WiFi AP on different channel.
The simplest way to do it, is to select a random channel, which fit my need.
Do you think its acceptable to integrate this way?

I've got also other ideas to achieve the same goal:
- Add an optional channel parameter when opening the AP
- Add a global config to set the channel
- ...

What do you think?

Best regards,
Vivien

Le 23/09/2021 à 14:44, Vivien Henriet a écrit :
> When the tethering mode is started, a WiFi ap is created using the fixed
> channel 1 (2412 MHz). There is no way to configure this channel.
>
> This patch make connman choose a random channel every time the ap is created.
> ---
>   plugins/wifi.c | 10 +++++++++-
>   1 file changed, 9 insertions(+), 1 deletion(-)
>
> diff --git a/plugins/wifi.c b/plugins/wifi.c
> index 578b4be7..936f1750 100644
> --- a/plugins/wifi.c
> +++ b/plugins/wifi.c
> @@ -3344,11 +3344,19 @@ static GSupplicantSSID *ssid_ap_init(const char *ssid, const char *passphrase)
>       if (!ap)
>               return NULL;
>
> +     /**
> +      * Choose a random channel in the range 1-11. Channels 12-14 are not
> +      * available worlwide.
> +      * Channels within this range are spaced 5 MHz apart from each other.
> +      */
> +     int channel = (rand() % 11) + 1;
> +     int freq = 2407 + channel * 5;
> +
>       ap->mode = G_SUPPLICANT_MODE_MASTER;
>       ap->ssid = ssid;
>       ap->ssid_len = strlen(ssid);
>       ap->scan_ssid = 0;
> -     ap->freq = 2412;
> +     ap->freq = freq;
>
>       if (!passphrase || strlen(passphrase) == 0) {
>               ap->security = G_SUPPLICANT_SECURITY_NONE;


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Re: [PATCH] wifi: Choose a random channel when opening an ap

[Daniel Wagner]

Hi Vivien,

On Wed, Sep 29, 2021 at 08:57:25AM +0000, HENRIET Vivien wrote:
> Hi Daniel,
> 
> Could you have a look to this patch?

Sorry for the delay. Anyway, I think it would be better to make this
configurable or smarter instead of a random channel selection. I just
checked what iwd is doing and if I got it right, the iwd daemon does the
channel selection itself.

> I would like to be able to open the WiFi AP on different channel.
> The simplest way to do it, is to select a random channel, which fit my need.
> Do you think its acceptable to integrate this way?

Random channel selection is a bit a wild solution :).

> I've got also other ideas to achieve the same goal:
> - Add an optional channel parameter when opening the AP

This is what I would suggest. Alternatively, can't we use some metrics
from the last scan to figure out which channel is crowded?

> - Add a global config to set the channel

Generally I would like to avoid adding more config option if there is a
way to figure it out.

Daniel

Re: [PATCH] wifi: Choose a random channel when opening an ap

[Michael Nazzareno Trimarchi]

Hi Daniel

On Wed, Sep 29, 2021 at 11:23 AM Daniel Wagner <wagi@monom.org> wrote:
>
> Hi Vivien,
>
> On Wed, Sep 29, 2021 at 08:57:25AM +0000, HENRIET Vivien wrote:
> > Hi Daniel,
> >
> > Could you have a look to this patch?
>
> Sorry for the delay. Anyway, I think it would be better to make this
> configurable or smarter instead of a random channel selection. I just
> checked what iwd is doing and if I got it right, the iwd daemon does the
> channel selection itself.
>
> > I would like to be able to open the WiFi AP on different channel.
> > The simplest way to do it, is to select a random channel, which fit my need.
> > Do you think its acceptable to integrate this way?
>
> Random channel selection is a bit a wild solution :).
>
> > I've got also other ideas to achieve the same goal:
> > - Add an optional channel parameter when opening the AP
>
> This is what I would suggest. Alternatively, can't we use some metrics
> from the last scan to figure out which channel is crowded?
>
> > - Add a global config to set the channel
>
> Generally I would like to avoid adding more config option if there is a
> way to figure it out.
>

I have sent a patch long time ago in order to add the possibility to
set the frequency of
access point. Can I resend?

Michael

> Daniel
>
>


-- 
Michael Nazzareno Trimarchi
Co-Founder & Chief Executive Officer
M. +39 347 913 2170
michael@amarulasolutions.com
__________________________________

Amarula Solutions BV
Joop Geesinkweg 125, 1114 AB, Amsterdam, NL
T. +31 (0)85 111 9172
info@amarulasolutions.com
www.amarulasolutions.com

Re: [PATCH] wifi: Choose a random channel when opening an ap

[Daniel Wagner]

Hi Michael,

On Mon, Oct 04, 2021 at 08:45:57AM +0200, Michael Nazzareno Trimarchi wrote:
> > Generally I would like to avoid adding more config option if there is a
> > way to figure it out.
> >
> 
> I have sent a patch long time ago in order to add the possibility to
> set the frequency of access point. Can I resend?

Oh, my bad. Sure please resend.

Thanks,
Daniel

Re: [PATCH] wifi: Choose a random channel when opening an ap

[Michael Nazzareno Trimarchi]

Hi

On Mon, Oct 4, 2021 at 9:09 AM Daniel Wagner <wagi@monom.org> wrote:
>
> Hi Michael,
>
> On Mon, Oct 04, 2021 at 08:45:57AM +0200, Michael Nazzareno Trimarchi wrote:
> > > Generally I would like to avoid adding more config option if there is a
> > > way to figure it out.
> > >
> >
> > I have sent a patch long time ago in order to add the possibility to
> > set the frequency of access point. Can I resend?
>
> Oh, my bad. Sure please resend.
>
> Thanks,
> Daniel

I'm rebasing it. I would like to know if:

  ident = technology->tethering_ident;
        passphrase = technology->tethering_passphrase;
        freq = technology->tethering_freq;

        __sync_synchronize();
        if (!technology->enabled)
                return -EACCES;

        bridge = __connman_tethering_get_bridge();
        if (!bridge)
                return -EOPNOTSUPP;

        if (technology->type == CONNMAN_SERVICE_TYPE_WIFI &&
            (!ident || !passphrase))
                return -EINVAL;

        for (tech_drivers = technology->driver_list; tech_drivers;
             tech_drivers = g_slist_next(tech_drivers)) {
                struct connman_technology_driver *driver = tech_drivers->data;

                if (!driver || !driver->set_tethering)
                        continue;

                err = driver->set_tethering(technology, ident, passphrase,
                                bridge, enabled, freq);

I can create a function to get

ident = technology->tethering_ident;
passphrase = technology->tethering_passphrase;
freq = technology->tethering_freq;

connman_tethering_get_params(techonology, &ident, &passphrase, &freq);

Michael




-- 
Michael Nazzareno Trimarchi
Co-Founder & Chief Executive Officer
M. +39 347 913 2170
michael@amarulasolutions.com
__________________________________

Amarula Solutions BV
Joop Geesinkweg 125, 1114 AB, Amsterdam, NL
T. +31 (0)85 111 9172
info@amarulasolutions.com
www.amarulasolutions.com

Re: [PATCH] wifi: Choose a random channel when opening an ap

[Daniel Wagner]

On 04.10.21 09:34, Michael Nazzareno Trimarchi wrote:
> I can create a function to get
> 
> ident = technology->tethering_ident;
> passphrase = technology->tethering_passphrase;
> freq = technology->tethering_freq;
> 
> connman_tethering_get_params(techonology, &ident, &passphrase, &freq);

Yes, that is what I had in mind. We need to retrieve these values from
the core/config somehow.

Re: [PATCH] wifi: Choose a random channel when opening an ap

[Michael Nazzareno Trimarchi]

Hi

On Mon, Oct 4, 2021 at 9:46 AM Daniel Wagner <wagi@monom.org> wrote:
>
> On 04.10.21 09:34, Michael Nazzareno Trimarchi wrote:
> > I can create a function to get
> >
> > ident = technology->tethering_ident;
> > passphrase = technology->tethering_passphrase;
> > freq = technology->tethering_freq;
> >
> > connman_tethering_get_params(techonology, &ident, &passphrase, &freq);
>
> Yes, that is what I had in mind. We need to retrieve these values from
> the core/config somehow.

I send an RFC in the mailing list just rebase some old patch and
adjust a bit to be more complete. I did not
time to test. I need to know if it can be a starting point or not.

Michael


-- 
Michael Nazzareno Trimarchi
Co-Founder & Chief Executive Officer
M. +39 347 913 2170
michael@amarulasolutions.com
__________________________________

Amarula Solutions BV
Joop Geesinkweg 125, 1114 AB, Amsterdam, NL
T. +31 (0)85 111 9172
info@amarulasolutions.com
www.amarulasolutions.com