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 "wps/wps.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 #ifdef CONFIG_WPS
  45 static int wpas_wps_in_use(struct wpa_config *conf)
  46 {
  47         struct wpa_ssid *ssid;
  48         int wps = 0;
  49
  50         for (ssid = conf->ssid; ssid; ssid = ssid->next) {
  51                 if (!(ssid->key_mgmt & WPA_KEY_MGMT_WPS))
  52                         continue;
  53
  54                 wps = 1;
  55                 if (!ssid->eap.phase1)
  56                         continue;
  57
  58                 if (os_strstr(ssid->eap.phase1, "pbc=1"))
  59                         return 2;
  60         }
  61
  62         return wps;
  63 }
  64 #endif /* CONFIG_WPS */
  65
  66 static void wpa_supplicant_scan(void *eloop_ctx, void *timeout_ctx)
  67 {
  68         struct wpa_supplicant *wpa_s = eloop_ctx;
  69         struct wpa_ssid *ssid;
  70         int enabled, scan_req = 0, ret;
  71         struct wpabuf *wps_ie = NULL;
  72         const u8 *extra_ie = NULL;
  73         size_t extra_ie_len = 0;
  74         int wps = 0;
  75
  76         if (wpa_s->disconnected && !wpa_s->scan_req)
  77                 return;
  78
  79         enabled = 0;
  80         ssid = wpa_s->conf->ssid;
  81         while (ssid) {
  82                 if (!ssid->disabled) {
  83                         enabled++;
  84                         break;
  85                 }
  86                 ssid = ssid->next;
  87         }
  88         if (!enabled && !wpa_s->scan_req) {
  89                 wpa_printf(MSG_DEBUG, "No enabled networks - do not scan");
  90                 wpa_supplicant_set_state(wpa_s, WPA_INACTIVE);
  91                 return;
  92         }
  93         scan_req = wpa_s->scan_req;
  94         wpa_s->scan_req = 0;
  95
  96         if (wpa_s->conf->ap_scan != 0 &&
  97             wpa_s->driver && IS_WIRED(wpa_s->driver)) {
  98                 wpa_printf(MSG_DEBUG, "Using wired authentication - "
  99                            "overriding ap_scan configuration");
 100                 wpa_s->conf->ap_scan = 0;
 101         }
 102
 103         if (wpa_s->conf->ap_scan == 0) {
 104                 wpa_supplicant_gen_assoc_event(wpa_s);
 105                 return;
 106         }
 107
 108         if (wpa_s->wpa_state == WPA_DISCONNECTED ||
 109             wpa_s->wpa_state == WPA_INACTIVE)
 110                 wpa_supplicant_set_state(wpa_s, WPA_SCANNING);
 111
 112         ssid = wpa_s->conf->ssid;
 113         if (wpa_s->prev_scan_ssid != BROADCAST_SSID_SCAN) {
 114                 while (ssid) {
 115                         if (ssid == wpa_s->prev_scan_ssid) {
 116                                 ssid = ssid->next;
 117                                 break;
 118                         }
 119                         ssid = ssid->next;
 120                 }
 121         }
 122         while (ssid) {
 123                 if (!ssid->disabled &&
 124                     (ssid->scan_ssid || wpa_s->conf->ap_scan == 2))
 125                         break;
 126                 ssid = ssid->next;
 127         }
 128
 129         if (scan_req != 2 && wpa_s->conf->ap_scan == 2) {
 130                 /*
 131                  * ap_scan=2 mode - try to associate with each SSID instead of
 132                  * scanning for each scan_ssid=1 network.
 133                  */
 134                 if (ssid == NULL) {
 135                         wpa_printf(MSG_DEBUG, "wpa_supplicant_scan: Reached "
 136                                    "end of scan list - go back to beginning");
 137                         wpa_s->prev_scan_ssid = BROADCAST_SSID_SCAN;
 138                         wpa_supplicant_req_scan(wpa_s, 0, 0);
 139                         return;
 140                 }
 141                 if (ssid->next) {
 142                         /* Continue from the next SSID on the next attempt. */
 143                         wpa_s->prev_scan_ssid = ssid;
 144                 } else {
 145                         /* Start from the beginning of the SSID list. */
 146                         wpa_s->prev_scan_ssid = BROADCAST_SSID_SCAN;
 147                 }
 148                 wpa_supplicant_associate(wpa_s, NULL, ssid);
 149                 return;
 150         }
 151
 152         wpa_printf(MSG_DEBUG, "Starting AP scan (%s SSID)",
 153                    ssid ? "specific": "broadcast");
 154         if (ssid) {
 155                 wpa_hexdump_ascii(MSG_DEBUG, "Scan SSID",
 156                                   ssid->ssid, ssid->ssid_len);
 157                 wpa_s->prev_scan_ssid = ssid;
 158         } else
 159                 wpa_s->prev_scan_ssid = BROADCAST_SSID_SCAN;
 160
 161 #ifdef CONFIG_WPS
 162         wps = wpas_wps_in_use(wpa_s->conf);
 163 #endif /* CONFIG_WPS */
 164
 165         if (wpa_s->scan_res_tried == 0 && wpa_s->conf->ap_scan == 1 &&
 166             !wpa_s->use_client_mlme && wps != 2) {
 167                 wpa_s->scan_res_tried++;
 168                 wpa_s->scan_req = scan_req;
 169                 wpa_printf(MSG_DEBUG, "Trying to get current scan results "
 170                            "first without requesting a new scan to speed up "
 171                            "initial association");
 172                 wpa_supplicant_event(wpa_s, EVENT_SCAN_RESULTS, NULL);
 173                 return;
 174         }
 175
 176 #ifdef CONFIG_WPS
 177         if (wps) {
 178                 wps_ie = wps_build_probe_req_ie(wps == 2, &wpa_s->wps->dev,
 179                                                 wpa_s->conf->uuid);
 180                 if (wps_ie) {
 181                         extra_ie = wpabuf_head(wps_ie);
 182                         extra_ie_len = wpabuf_len(wps_ie);
 183                 }
 184         }
 185 #endif /* CONFIG_WPS */
 186
 187         if (wpa_s->use_client_mlme) {
 188                 ieee80211_sta_set_probe_req_ie(wpa_s, extra_ie, extra_ie_len);
 189                 ret = ieee80211_sta_req_scan(wpa_s, ssid ? ssid->ssid : NULL,
 190                                              ssid ? ssid->ssid_len : 0);
 191         } else {
 192                 wpa_drv_set_probe_req_ie(wpa_s, extra_ie, extra_ie_len);
 193                 ret = wpa_drv_scan(wpa_s, ssid ? ssid->ssid : NULL,
 194                                    ssid ? ssid->ssid_len : 0);
 195         }
 196
 197         wpabuf_free(wps_ie);
 198
 199         if (ret) {
 200                 wpa_printf(MSG_WARNING, "Failed to initiate AP scan.");
 201                 wpa_supplicant_req_scan(wpa_s, 10, 0);
 202         }
 203 }
 204
 205
 206 /**
 207  * wpa_supplicant_req_scan - Schedule a scan for neighboring access points
 208  * @wpa_s: Pointer to wpa_supplicant data
 209  * @sec: Number of seconds after which to scan
 210  * @usec: Number of microseconds after which to scan
 211  *
 212  * This function is used to schedule a scan for neighboring access points after
 213  * the specified time.
 214  */
 215 void wpa_supplicant_req_scan(struct wpa_supplicant *wpa_s, int sec, int usec)
 216 {
 217         /* If there's at least one network that should be specifically scanned
 218          * then don't cancel the scan and reschedule.  Some drivers do
 219          * background scanning which generates frequent scan results, and that
 220          * causes the specific SSID scan to get continually pushed back and
 221          * never happen, which causes hidden APs to never get probe-scanned.
 222          */
 223         if (eloop_is_timeout_registered(wpa_supplicant_scan, wpa_s, NULL) &&
 224             wpa_s->conf->ap_scan == 1) {
 225                 struct wpa_ssid *ssid = wpa_s->conf->ssid;
 226
 227                 while (ssid) {
 228                         if (!ssid->disabled && ssid->scan_ssid)
 229                                 break;
 230                         ssid = ssid->next;
 231                 }
 232                 if (ssid) {
 233                         wpa_msg(wpa_s, MSG_DEBUG, "Not rescheduling scan to "
 234                                 "ensure that specific SSID scans occur");
 235                         return;
 236                 }
 237         }
 238
 239         wpa_msg(wpa_s, MSG_DEBUG, "Setting scan request: %d sec %d usec",
 240                 sec, usec);
 241         eloop_cancel_timeout(wpa_supplicant_scan, wpa_s, NULL);
 242         eloop_register_timeout(sec, usec, wpa_supplicant_scan, wpa_s, NULL);
 243 }
 244
 245
 246 /**
 247  * wpa_supplicant_cancel_scan - Cancel a scheduled scan request
 248  * @wpa_s: Pointer to wpa_supplicant data
 249  *
 250  * This function is used to cancel a scan request scheduled with
 251  * wpa_supplicant_req_scan().
 252  */
 253 void wpa_supplicant_cancel_scan(struct wpa_supplicant *wpa_s)
 254 {
 255         wpa_msg(wpa_s, MSG_DEBUG, "Cancelling scan request");
 256         eloop_cancel_timeout(wpa_supplicant_scan, wpa_s, NULL);
 257 }