Updated through tag hostap_2_5 from git://w1.fi/hostap.git

[mech_eap.git] / libeap / wpa_supplicant / bgscan_simple.c

diff --git a/libeap/wpa_supplicant/bgscan_simple.c b/libeap/wpa_supplicant/bgscan_simple.c
index 409d9ce..a467cc5 100644 (file)
--- a/libeap/wpa_supplicant/bgscan_simple.c
+++ b/libeap/wpa_supplicant/bgscan_simple.c
@@ -2,14 +2,8 @@
  * WPA Supplicant - background scan and roaming module: simple
  * Copyright (c) 2009-2010, Jouni Malinen <j@w1.fi>
  *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License version 2 as
- * published by the Free Software Foundation.
- *
- * Alternatively, this software may be distributed under the terms of BSD
- * license.
- *
- * See README and COPYING for more details.
+ * This software may be distributed under the terms of the BSD license.
+ * See README for more details.
  */
 
 #include "includes.h"
@@ -28,9 +22,11 @@ struct bgscan_simple_data {
        const struct wpa_ssid *ssid;
        int scan_interval;
        int signal_threshold;
+       int short_scan_count; /* counter for scans using short scan interval */
+       int max_short_scans; /* maximum times we short-scan before back-off */
        int short_interval; /* use if signal < threshold */
        int long_interval; /* use if signal > threshold */
-       struct os_time last_bgscan;
+       struct os_reltime last_bgscan;
 };
 
 
@@ -57,8 +53,30 @@ static void bgscan_simple_timeout(void *eloop_ctx, void *timeout_ctx)
                wpa_printf(MSG_DEBUG, "bgscan simple: Failed to trigger scan");
                eloop_register_timeout(data->scan_interval, 0,
                                       bgscan_simple_timeout, data, NULL);
-       } else
-               os_get_time(&data->last_bgscan);
+       } else {
+               if (data->scan_interval == data->short_interval) {
+                       data->short_scan_count++;
+                       /*
+                        * Spend at most the duration of a long scan interval
+                        * scanning at the short scan interval. After that,
+                        * revert to the long scan interval.
+                        */
+                       if (data->short_scan_count > data->max_short_scans) {
+                               data->scan_interval = data->long_interval;
+                               wpa_printf(MSG_DEBUG, "bgscan simple: Backing "
+                                          "off to long scan interval");
+                       }
+               } else if (data->short_scan_count > 0) {
+                       /*
+                        * If we lasted a long scan interval without any
+                        * CQM triggers, decrease the short-scan count,
+                        * which allows 1 more short-scan interval to
+                        * occur in the future when CQM triggers.
+                        */
+                       data->short_scan_count--;
+               }
+               os_get_reltime(&data->last_bgscan);
+       }
 }
 
 
@@ -122,6 +140,16 @@ static void * bgscan_simple_init(struct wpa_supplicant *wpa_s,
        }
 
        data->scan_interval = data->short_interval;
+       data->max_short_scans = data->long_interval / data->short_interval + 1;
+       if (data->signal_threshold) {
+               /* Poll for signal info to set initial scan interval */
+               struct wpa_signal_info siginfo;
+               if (wpa_drv_signal_poll(wpa_s, &siginfo) == 0 &&
+                   siginfo.current_signal >= data->signal_threshold)
+                       data->scan_interval = data->long_interval;
+       }
+       wpa_printf(MSG_DEBUG, "bgscan simple: Init scan interval: %d",
+                  data->scan_interval);
        eloop_register_timeout(data->scan_interval, 0, bgscan_simple_timeout,
                               data, NULL);
 
@@ -131,7 +159,7 @@ static void * bgscan_simple_init(struct wpa_supplicant *wpa_s,
         * us skip an immediate new scan in cases where the current signal
         * level is below the bgscan threshold.
         */
-       os_get_time(&data->last_bgscan);
+       os_get_reltime(&data->last_bgscan);
 
        return data;
 }
@@ -183,7 +211,7 @@ static void bgscan_simple_notify_signal_change(void *priv, int above,
 {
        struct bgscan_simple_data *data = priv;
        int scan = 0;
-       struct os_time now;
+       struct os_reltime now;
 
        if (data->short_interval == data->long_interval ||
            data->signal_threshold == 0)
@@ -197,9 +225,28 @@ static void bgscan_simple_notify_signal_change(void *priv, int above,
                wpa_printf(MSG_DEBUG, "bgscan simple: Start using short "
                           "bgscan interval");
                data->scan_interval = data->short_interval;
-               os_get_time(&now);
-               if (now.sec > data->last_bgscan.sec + 1)
+               os_get_reltime(&now);
+               if (now.sec > data->last_bgscan.sec + 1 &&
+                   data->short_scan_count <= data->max_short_scans)
+                       /*
+                        * If we haven't just previously (<1 second ago)
+                        * performed a scan, and we haven't depleted our
+                        * budget for short-scans, perform a scan
+                        * immediately.
+                        */
                        scan = 1;
+               else if (data->last_bgscan.sec + data->long_interval >
+                        now.sec + data->scan_interval) {
+                       /*
+                        * Restart scan interval timer if currently scheduled
+                        * scan is too far in the future.
+                        */
+                       eloop_cancel_timeout(bgscan_simple_timeout, data,
+                                            NULL);
+                       eloop_register_timeout(data->scan_interval, 0,
+                                              bgscan_simple_timeout, data,
+                                              NULL);
+               }
        } else if (data->scan_interval == data->short_interval && above) {
                wpa_printf(MSG_DEBUG, "bgscan simple: Start using long bgscan "
                           "interval");
@@ -212,7 +259,7 @@ static void bgscan_simple_notify_signal_change(void *priv, int above,
                 * Signal dropped further 4 dB. Request a new scan if we have
                 * not yet scanned in a while.
                 */
-               os_get_time(&now);
+               os_get_reltime(&now);
                if (now.sec > data->last_bgscan.sec + 10)
                        scan = 1;
        }