Motivation for this change

Compile wpa_supplicant with the BGSCAN module enabled. This allows the user to configure an SSID to use the bgscan module like so (excerpt from wpa_supplicant.conf):

network={
	...network config...
	bgscan="simple:30:-75:500"
}

The module supports the following configuration:

# bgscan: Background scanning
# wpa_supplicant behavior for background scanning can be specified by
# configuring a bgscan module. These modules are responsible for requesting
# background scans for the purpose of roaming within an ESS (i.e., within a
# single network block with all the APs using the same SSID). The bgscan
# parameter uses following format: "<bgscan module name>:<module parameters>"
# Following bgscan modules are available:
# simple - Periodic background scans based on signal strength
# bgscan="simple:<short bgscan interval in seconds>:<signal strength threshold>:
# <long interval>"
# bgscan="simple:30:-45:300"
# learn - Learn channels used by the network and try to avoid bgscans on other
# channels (experimental)
# bgscan="learn:<short bgscan interval in seconds>:<signal strength threshold>:
# <long interval>[:<database file name>]"
# bgscan="learn:30:-45:300:/etc/wpa_supplicant/network1.bgscan"
# Explicitly disable bgscan by setting
# bgscan=""

I have been running with this module enabled on my wpa_supplicant for around 4 months. I waited this long to ensure that there were no negative effects with the module disabled. At this point I am fairly confident that this is a safe thing to enable globally, and should only take effect if the user specifies a bgscan configuration in their wpa_supplicant.conf.

Things done

Please check what applies. Note that these are not hard requirements but merely serve as information for reviewers.

• Tested using sandboxing
  (nix.useSandbox on NixOS,
  or option build-use-sandbox in nix.conf
  on non-NixOS)
• Built on platform(s)
  • NixOS
  • macOS
  • Linux
• Tested via one or more NixOS test(s) if existing and applicable for the change (look inside nixos/tests)
• Tested compilation of all pkgs that depend on this change using nix-shell -p nox --run "nox-review wip"
• Tested execution of all binary files (usually in ./result/bin/)
• Fits CONTRIBUTING.md.