sending EAPOL Logoff on SIGTERM for wired ethernet connections

[Simner, John]

An embedded product with a wired ethernet connection to a switch port must send a EAPOL logoff to the switch port when the product is rebooted.
Prior to the reboot or shutdown, the embedded product sends a SIGTERM to all running processes.
So, the wpa_supplicant must send the EAPOL logoff on receipt of the SIGTERM.

The following patch achieves this... 

cat 0.7.3SendEapolLogoffOnSigTerm.patch
--- wpa_supplicant-0.7.3/wpa_supplicant/wpa_supplicant.c        2010-09-07 17:43:39.000000000 +0200
+++ /tmp/src/wpa_supplicant/wpa_supplicant.c    2012-05-09 15:33:36.000000000 +0200
@@ -577,6 +577,7 @@ static void wpa_supplicant_terminate(int
        struct wpa_global *global = signal_ctx;
        struct wpa_supplicant *wpa_s;
        for (wpa_s = global->ifaces; wpa_s; wpa_s = wpa_s->next) {
+               eapol_sm_notify_logoff(wpa_s->eapol, TRUE);
                wpa_msg(wpa_s, MSG_INFO, WPA_EVENT_TERMINATING "- signal %d "
                        "received", sig);
        }

This is the simplest solution and relies upon the underlying drivers to know whether they should sent the EAPOL logoff or not.
This approach is based on what happens when wpa_cli logoff is sent to the wpa control interface.

The wpa control interface could not be used because when the embedded product is rebooted, SIGTERM would be sent to the two different processes; wpa_supplicant and the one sending the wpa_cli logoff.  There is a potential race condition as there is no guarantee which process would handle the SIGTERM first and whether the wpa_cli logoff is sent, handled, and the EAPOL logoff is actually sent.

Therefore, the simplest solution of wpa_supplicant handling the SIGTERM and sending the EAPOL logoff has been implemented.
If there is an alternative solution, please let us know.

Thanks..
John


John Simner BSc(Hons) MSc CEng. MIET
Software Engineer
Siemens Enterprise Communications Limited 

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