dist/wpa/wpa_supplicant/scan.c

   1 /*
   2  * WPA Supplicant - Scanning
   3  * Copyright (c) 2003-2008, 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 "config.h"
  20 #include "wpa_supplicant_i.h"
  21 #include "mlme.h"
  22 #include "uuid.h"
  23
  24
  25 static void wpa_supplicant_gen_assoc_event(struct wpa_supplicant *wpa_s)
  26 {
  27         struct wpa_ssid *ssid;
  28         union wpa_event_data data;
  29
  30         ssid = wpa_supplicant_get_ssid(wpa_s);
  31         if (ssid == NULL)
  32                 return;
  33
  34         if (wpa_s->current_ssid == NULL)
  35                 wpa_s->current_ssid = ssid;
  36         wpa_supplicant_initiate_eapol(wpa_s);
  37         wpa_printf(MSG_DEBUG, "Already associated with a configured network - "
  38                    "generating associated event");
  39         os_memset(&data, 0, sizeof(data));
  40         wpa_supplicant_event(wpa_s, EVENT_ASSOC, &data);
  41 }
  42
  43
  44 static void wpa_supplicant_scan(void *eloop_ctx, void *timeout_ctx)
  45 {
  46         struct wpa_supplicant *wpa_s = eloop_ctx;
  47         struct wpa_ssid *ssid;
  48         int enabled, scan_req = 0, ret;
  49         const u8 *extra_ie = NULL;
  50         size_t extra_ie_len = 0;
  51
  52         if (wpa_s->disconnected && !wpa_s->scan_req)
  53                 return;
  54
  55         enabled = 0;
  56         ssid = wpa_s->conf->ssid;
  57         while (ssid) {
  58                 if (!ssid->disabled) {
  59                         enabled++;
  60                         break;
  61                 }
  62                 ssid = ssid->next;
  63         }
  64         if (!enabled && !wpa_s->scan_req) {
  65                 wpa_printf(MSG_DEBUG, "No enabled networks - do not scan");
  66                 wpa_supplicant_set_state(wpa_s, WPA_INACTIVE);
  67                 return;
  68         }
  69         scan_req = wpa_s->scan_req;
  70         wpa_s->scan_req = 0;
  71
  72         if (wpa_s->conf->ap_scan != 0 &&
  73             wpa_s->driver && os_strcmp(wpa_s->driver->name, "wired") == 0) {
  74                 wpa_printf(MSG_DEBUG, "Using wired driver - overriding "
  75                            "ap_scan configuration");
  76                 wpa_s->conf->ap_scan = 0;
  77         }
  78
  79         if (wpa_s->conf->ap_scan == 0) {
  80                 wpa_supplicant_gen_assoc_event(wpa_s);
  81                 return;
  82         }
  83
  84         if (wpa_s->wpa_state == WPA_DISCONNECTED ||
  85             wpa_s->wpa_state == WPA_INACTIVE)
  86                 wpa_supplicant_set_state(wpa_s, WPA_SCANNING);
  87
  88         ssid = wpa_s->conf->ssid;
  89         if (wpa_s->prev_scan_ssid != BROADCAST_SSID_SCAN) {
  90                 while (ssid) {
  91                         if (ssid == wpa_s->prev_scan_ssid) {
  92                                 ssid = ssid->next;
  93                                 break;
  94                         }
  95                         ssid = ssid->next;
  96                 }
  97         }
  98         while (ssid) {
  99                 if (!ssid->disabled &&
 100                     (ssid->scan_ssid || wpa_s->conf->ap_scan == 2))
 101                         break;
 102                 ssid = ssid->next;
 103         }
 104
 105         if (scan_req != 2 && wpa_s->conf->ap_scan == 2) {
 106                 /*
 107                  * ap_scan=2 mode - try to associate with each SSID instead of
 108                  * scanning for each scan_ssid=1 network.
 109                  */
 110                 if (ssid == NULL) {
 111                         wpa_printf(MSG_DEBUG, "wpa_supplicant_scan: Reached "
 112                                    "end of scan list - go back to beginning");
 113                         wpa_s->prev_scan_ssid = BROADCAST_SSID_SCAN;
 114                         wpa_supplicant_req_scan(wpa_s, 0, 0);
 115                         return;
 116                 }
 117                 if (ssid->next) {
 118                         /* Continue from the next SSID on the next attempt. */
 119                         wpa_s->prev_scan_ssid = ssid;
 120                 } else {
 121                         /* Start from the beginning of the SSID list. */
 122                         wpa_s->prev_scan_ssid = BROADCAST_SSID_SCAN;
 123                 }
 124                 wpa_supplicant_associate(wpa_s, NULL, ssid);
 125                 return;
 126         }
 127
 128         wpa_printf(MSG_DEBUG, "Starting AP scan (%s SSID)",
 129                    ssid ? "specific": "broadcast");
 130         if (ssid) {
 131                 wpa_hexdump_ascii(MSG_DEBUG, "Scan SSID",
 132                                   ssid->ssid, ssid->ssid_len);
 133                 wpa_s->prev_scan_ssid = ssid;
 134         } else
 135                 wpa_s->prev_scan_ssid = BROADCAST_SSID_SCAN;
 136
 137         if (wpa_s->scan_res_tried == 0 && wpa_s->conf->ap_scan == 1 &&
 138             !wpa_s->use_client_mlme) {
 139                 wpa_s->scan_res_tried++;
 140                 wpa_printf(MSG_DEBUG, "Trying to get current scan results "
 141                            "first without requesting a new scan to speed up "
 142                            "initial association");
 143                 wpa_supplicant_event(wpa_s, EVENT_SCAN_RESULTS, NULL);
 144                 return;
 145         }
 146
 147         if (wpa_s->use_client_mlme) {
 148                 ieee80211_sta_set_probe_req_ie(wpa_s, extra_ie, extra_ie_len);
 149                 ret = ieee80211_sta_req_scan(wpa_s, ssid ? ssid->ssid : NULL,
 150                                              ssid ? ssid->ssid_len : 0);
 151         } else {
 152                 wpa_drv_set_probe_req_ie(wpa_s, extra_ie, extra_ie_len);
 153                 ret = wpa_drv_scan(wpa_s, ssid ? ssid->ssid : NULL,
 154                                    ssid ? ssid->ssid_len : 0);
 155         }
 156
 157         if (ret) {
 158                 wpa_printf(MSG_WARNING, "Failed to initiate AP scan.");
 159                 wpa_supplicant_req_scan(wpa_s, 10, 0);
 160         }
 161 }
 162
 163
 164 /**
 165  * wpa_supplicant_req_scan - Schedule a scan for neighboring access points
 166  * @wpa_s: Pointer to wpa_supplicant data
 167  * @sec: Number of seconds after which to scan
 168  * @usec: Number of microseconds after which to scan
 169  *
 170  * This function is used to schedule a scan for neighboring access points after
 171  * the specified time.
 172  */
 173 void wpa_supplicant_req_scan(struct wpa_supplicant *wpa_s, int sec, int usec)
 174 {
 175         /* If there's at least one network that should be specifically scanned
 176          * then don't cancel the scan and reschedule.  Some drivers do
 177          * background scanning which generates frequent scan results, and that
 178          * causes the specific SSID scan to get continually pushed back and
 179          * never happen, which causes hidden APs to never get probe-scanned.
 180          */
 181         if (eloop_is_timeout_registered(wpa_supplicant_scan, wpa_s, NULL) &&
 182             wpa_s->conf->ap_scan == 1) {
 183                 struct wpa_ssid *ssid = wpa_s->conf->ssid;
 184
 185                 while (ssid) {
 186                         if (!ssid->disabled && ssid->scan_ssid)
 187                                 break;
 188                         ssid = ssid->next;
 189                 }
 190                 if (ssid) {
 191                         wpa_msg(wpa_s, MSG_DEBUG, "Not rescheduling scan to "
 192                                 "ensure that specific SSID scans occur");
 193                         return;
 194                 }
 195         }
 196
 197         wpa_msg(wpa_s, MSG_DEBUG, "Setting scan request: %d sec %d usec",
 198                 sec, usec);
 199         eloop_cancel_timeout(wpa_supplicant_scan, wpa_s, NULL);
 200         eloop_register_timeout(sec, usec, wpa_supplicant_scan, wpa_s, NULL);
 201 }
 202
 203
 204 /**
 205  * wpa_supplicant_cancel_scan - Cancel a scheduled scan request
 206  * @wpa_s: Pointer to wpa_supplicant data
 207  *
 208  * This function is used to cancel a scan request scheduled with
 209  * wpa_supplicant_req_scan().
 210  */
 211 void wpa_supplicant_cancel_scan(struct wpa_supplicant *wpa_s)
 212 {
 213         wpa_msg(wpa_s, MSG_DEBUG, "Cancelling scan request");
 214         eloop_cancel_timeout(wpa_supplicant_scan, wpa_s, NULL);
 215 }