Initial Monitor Mode support

[DrSchottky]

Added driver patches to enable monitor mode and provided usage example.
Captures raw 802.11 frames w/ or w/o radiotap header (Nexmon required)

Complementary PR
seemoo-lab/nexmon#579

[jlinktu]

Thank you @DrSchottky for your contribution.
I still have to check, but I guess the nexmon patch should be fine.

Regarding this PR:
I think it makes more sense to split up into two applications:

• monitor: which works with the default firmware, only requires the patched driver
• monitor_radiotap: which additionally requires the nexmon patch introduced by Add monitor mode support for Raspberry Pi Pico W (bcm43439a0) FW 7_95_49_2271bb6 nexmon#579

The project is supposed to be configurable with the NO_NEXMON flag, there shouldn't be the need to manually uncomment for switching between w/ and w/o nexmon firmware. Instead, one application sub-directory for the monitor w/o nexmon firmware and one application sub-directory for the monitor_radiotap w/ nexmon firmware should exist, where the latter only gets build if NO_NEXMON is not defined, like it is done for the ioctl_test application here. The build process for the nexmon firmware should also be considered in the CMakeLists.txt of the monitor_radiotap application, just like it is done for the ioctl_test application here.

Regarding the cyw43-driver patch to enable monitor mode: As the modifications are more than minimal, which might prevent us from keeping up with main repo in the future, does it make sense to move this to the main cyw43-driver repo instead? Maybe with a CYW43_MONITOR flag.

Let me know what you think.

[DrSchottky]

Hello @jlinktu
Okay for splitting the examples.
Regarding cyw43-driver, do you mean to upstream the patch? I can try, but I have little hope that such a change will be approved.
In case it's not, do you think it would be more manageable forking cyw43-driver, patching it, and then importing that?

[jlinktu]

I was thinking about upstreaming it. I mean, monitor mode support seems legit to be included in the driver. If georgerobotics do not want it, we can still use the local patch instead. -> We can add it for now and if they decide to accept it, we can remove our local one. :)

[Frostie314159]

Would it be possible to allow for the transmission of raw frames? i.e. Injection

[jlinktu]

With the right patch in place, yes, this would be possible.

[Frostie314159]

Do you have some pointers where I should look for this, since I would love to implement AWDL and ESP-NOW on the rp pico w, but lack support for injection.