How nl80211 library & cfg80211 work?

Question

I want to learn about how nl80211 and cfg80211 works in detail. Function flow, how nl80211 interact with network tools like wpa_

Answer 1

See my reply to How to learn the structure of Linux wireless drivers (mac80211)?

In wpa_supplicant, you can follow the code in src/drivers/driver_nl80211.c. This is a wpa_supplicant driver (not a kernel driver but an abstraction used in wpa_supplicant code) which uses libnl to communicate with the kernel cfg80211 module. When wpa_supplicant issues a scan for example then wpa_driver_nl80211_scan gets called. It builds the netlink message with a command called NL80211_CMD_TRIGGER_SCAN and with all the parameters required for the scan.