wpa_supplicant/bgscan_simple.c

   1 /*
   2  * WPA Supplicant - background scan and roaming module: simple
   3  * Copyright (c) 2009, Jouni Malinen <j@w1.fi>
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License version 2 as
   7  * published by the Free Software Foundation.
   8  *
   9  * Alternatively, this software may be distributed under the terms of BSD
  10  * license.
  11  *
  12  * See README and COPYING for more details.
  13  */
  14
  15 #include "includes.h"
  16
  17 #include "common.h"
  18 #include "eloop.h"
  19 #include "drivers/driver.h"
  20 #include "config_ssid.h"
  21 #include "wpa_supplicant_i.h"
  22 #include "bgscan.h"
  23
  24 struct bgscan_simple_data {
  25         struct wpa_supplicant *wpa_s;
  26         const struct wpa_ssid *ssid;
  27         int scan_interval;
  28 };
  29
  30
  31 static void bgscan_simple_timeout(void *eloop_ctx, void *timeout_ctx)
  32 {
  33         struct bgscan_simple_data *data = eloop_ctx;
  34         struct wpa_supplicant *wpa_s = data->wpa_s;
  35         struct wpa_driver_scan_params params;
  36
  37         os_memset(&params, 0, sizeof(params));
  38         params.num_ssids = 1;
  39         params.ssids[0].ssid = data->ssid->ssid;
  40         params.ssids[0].ssid_len = data->ssid->ssid_len;
  41         params.freqs = data->ssid->scan_freq;
  42
  43         /*
  44          * A more advanced bgscan module would learn about most like channels
  45          * over time and request scans only for some channels (probing others
  46          * every now and then) to reduce effect on the data connection.
  47          */
  48
  49         wpa_printf(MSG_DEBUG, "bgscan simple: Request a background scan");
  50         if (wpa_supplicant_trigger_scan(wpa_s, &params)) {
  51                 wpa_printf(MSG_DEBUG, "bgscan simple: Failed to trigger scan");
  52                 eloop_register_timeout(data->scan_interval, 0,
  53                                        bgscan_simple_timeout, data, NULL);
  54         }
  55 }
  56
  57
  58 static void * bgscan_simple_init(struct wpa_supplicant *wpa_s,
  59                                  const char *params,
  60                                  const struct wpa_ssid *ssid)
  61 {
  62         struct bgscan_simple_data *data;
  63
  64         data = os_zalloc(sizeof(*data));
  65         if (data == NULL)
  66                 return NULL;
  67         data->wpa_s = wpa_s;
  68         data->ssid = ssid;
  69         if (params)
  70                 data->scan_interval = atoi(params);
  71         if (data->scan_interval <= 0)
  72                 data->scan_interval = 30;
  73         eloop_register_timeout(data->scan_interval, 0, bgscan_simple_timeout,
  74                                data, NULL);
  75         return data;
  76 }
  77
  78
  79 static void bgscan_simple_deinit(void *priv)
  80 {
  81         struct bgscan_simple_data *data = priv;
  82         eloop_cancel_timeout(bgscan_simple_timeout, data, NULL);
  83         os_free(data);
  84 }
  85
  86
  87 static int bgscan_simple_notify_scan(void *priv)
  88 {
  89         struct bgscan_simple_data *data = priv;
  90
  91         wpa_printf(MSG_DEBUG, "bgscan simple: scan result notification");
  92
  93         eloop_cancel_timeout(bgscan_simple_timeout, data, NULL);
  94         eloop_register_timeout(data->scan_interval, 0, bgscan_simple_timeout,
  95                                data, NULL);
  96
  97         /*
  98          * A more advanced bgscan could process scan results internally, select
  99          * the BSS and request roam if needed. This sample uses the existing
 100          * BSS/ESS selection routine. Change this to return 1 if selection is
 101          * done inside the bgscan module.
 102          */
 103
 104         return 0;
 105 }
 106
 107
 108 static void bgscan_simple_notify_beacon_loss(void *priv)
 109 {
 110         wpa_printf(MSG_DEBUG, "bgscan simple: beacon loss");
 111         /* TODO: speed up background scanning */
 112 }
 113
 114
 115 static void bgscan_simple_notify_signal_change(void *priv)
 116 {
 117         wpa_printf(MSG_DEBUG, "bgscan simple: signal level changed");
 118         /* TODO: if signal strength dropped enough, speed up background
 119          * scanning */
 120 }
 121
 122
 123 const struct bgscan_ops bgscan_simple_ops = {
 124         .name = "simple",
 125         .init = bgscan_simple_init,
 126         .deinit = bgscan_simple_deinit,
 127         .notify_scan = bgscan_simple_notify_scan,
 128         .notify_beacon_loss = bgscan_simple_notify_beacon_loss,
 129         .notify_signal_change = bgscan_simple_notify_signal_change,
 130 };