wpa_supplicant/scan.c

   1 /*
   2  * WPA Supplicant - Scanning
   3  * Copyright (c) 2003-2010, 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 "utils/includes.h"
  16
  17 #include "utils/common.h"
  18 #include "utils/eloop.h"
  19 #include "common/ieee802_11_defs.h"
  20 #include "config.h"
  21 #include "wpa_supplicant_i.h"
  22 #include "driver_i.h"
  23 #include "mlme.h"
  24 #include "wps_supplicant.h"
  25 #include "notify.h"
  26 #include "bss.h"
  27 #include "scan.h"
  28
  29
  30 static void wpa_supplicant_gen_assoc_event(struct wpa_supplicant *wpa_s)
  31 {
  32         struct wpa_ssid *ssid;
  33         union wpa_event_data data;
  34
  35         ssid = wpa_supplicant_get_ssid(wpa_s);
  36         if (ssid == NULL)
  37                 return;
  38
  39         if (wpa_s->current_ssid == NULL) {
  40                 wpa_s->current_ssid = ssid;
  41                 if (wpa_s->current_ssid != NULL)
  42                         wpas_notify_network_changed(wpa_s);
  43         }
  44         wpa_supplicant_initiate_eapol(wpa_s);
  45         wpa_printf(MSG_DEBUG, "Already associated with a configured network - "
  46                    "generating associated event");
  47         os_memset(&data, 0, sizeof(data));
  48         wpa_supplicant_event(wpa_s, EVENT_ASSOC, &data);
  49 }
  50
  51
  52 #ifdef CONFIG_WPS
  53 static int wpas_wps_in_use(struct wpa_config *conf,
  54                            enum wps_request_type *req_type)
  55 {
  56         struct wpa_ssid *ssid;
  57         int wps = 0;
  58
  59         for (ssid = conf->ssid; ssid; ssid = ssid->next) {
  60                 if (!(ssid->key_mgmt & WPA_KEY_MGMT_WPS))
  61                         continue;
  62
  63                 wps = 1;
  64                 *req_type = wpas_wps_get_req_type(ssid);
  65                 if (!ssid->eap.phase1)
  66                         continue;
  67
  68                 if (os_strstr(ssid->eap.phase1, "pbc=1"))
  69                         return 2;
  70         }
  71
  72         return wps;
  73 }
  74 #endif /* CONFIG_WPS */
  75
  76
  77 int wpa_supplicant_enabled_networks(struct wpa_config *conf)
  78 {
  79         struct wpa_ssid *ssid = conf->ssid;
  80         while (ssid) {
  81                 if (!ssid->disabled)
  82                         return 1;
  83                 ssid = ssid->next;
  84         }
  85         return 0;
  86 }
  87
  88
  89 static void wpa_supplicant_assoc_try(struct wpa_supplicant *wpa_s,
  90                                      struct wpa_ssid *ssid)
  91 {
  92         while (ssid) {
  93                 if (!ssid->disabled)
  94                         break;
  95                 ssid = ssid->next;
  96         }
  97
  98         /* ap_scan=2 mode - try to associate with each SSID. */
  99         if (ssid == NULL) {
 100                 wpa_printf(MSG_DEBUG, "wpa_supplicant_scan: Reached "
 101                            "end of scan list - go back to beginning");
 102                 wpa_s->prev_scan_ssid = WILDCARD_SSID_SCAN;
 103                 wpa_supplicant_req_scan(wpa_s, 0, 0);
 104                 return;
 105         }
 106         if (ssid->next) {
 107                 /* Continue from the next SSID on the next attempt. */
 108                 wpa_s->prev_scan_ssid = ssid;
 109         } else {
 110                 /* Start from the beginning of the SSID list. */
 111                 wpa_s->prev_scan_ssid = WILDCARD_SSID_SCAN;
 112         }
 113         wpa_supplicant_associate(wpa_s, NULL, ssid);
 114 }
 115
 116
 117 static int int_array_len(const int *a)
 118 {
 119         int i;
 120         for (i = 0; a && a[i]; i++)
 121                 ;
 122         return i;
 123 }
 124
 125
 126 static void int_array_concat(int **res, const int *a)
 127 {
 128         int reslen, alen, i;
 129         int *n;
 130
 131         reslen = int_array_len(*res);
 132         alen = int_array_len(a);
 133
 134         n = os_realloc(*res, (reslen + alen + 1) * sizeof(int));
 135         if (n == NULL) {
 136                 os_free(*res);
 137                 *res = NULL;
 138                 return;
 139         }
 140         for (i = 0; i <= alen; i++)
 141                 n[reslen + i] = a[i];
 142         *res = n;
 143 }
 144
 145
 146 static int freq_cmp(const void *a, const void *b)
 147 {
 148         int _a = *(int *) a;
 149         int _b = *(int *) b;
 150
 151         if (_a == 0)
 152                 return 1;
 153         if (_b == 0)
 154                 return -1;
 155         return _a - _b;
 156 }
 157
 158
 159 static void int_array_sort_unique(int *a)
 160 {
 161         int alen;
 162         int i, j;
 163
 164         if (a == NULL)
 165                 return;
 166
 167         alen = int_array_len(a);
 168         qsort(a, alen, sizeof(int), freq_cmp);
 169
 170         i = 0;
 171         j = 1;
 172         while (a[i] && a[j]) {
 173                 if (a[i] == a[j]) {
 174                         j++;
 175                         continue;
 176                 }
 177                 a[++i] = a[j++];
 178         }
 179         if (a[i])
 180                 i++;
 181         a[i] = 0;
 182 }
 183
 184
 185 int wpa_supplicant_trigger_scan(struct wpa_supplicant *wpa_s,
 186                                 struct wpa_driver_scan_params *params)
 187 {
 188         int ret;
 189
 190         wpa_supplicant_notify_scanning(wpa_s, 1);
 191
 192         if (wpa_s->drv_flags & WPA_DRIVER_FLAGS_USER_SPACE_MLME)
 193                 ret = ieee80211_sta_req_scan(wpa_s, params);
 194         else
 195                 ret = wpa_drv_scan(wpa_s, params);
 196
 197         if (ret) {
 198                 wpa_supplicant_notify_scanning(wpa_s, 0);
 199                 wpas_notify_scan_done(wpa_s, 0);
 200         } else
 201                 wpa_s->scan_runs++;
 202
 203         return ret;
 204 }
 205
 206
 207 static void wpa_supplicant_scan(void *eloop_ctx, void *timeout_ctx)
 208 {
 209         struct wpa_supplicant *wpa_s = eloop_ctx;
 210         struct wpa_ssid *ssid;
 211         int scan_req = 0, ret;
 212         struct wpabuf *wps_ie = NULL;
 213         int wps = 0;
 214 #ifdef CONFIG_WPS
 215         enum wps_request_type req_type = WPS_REQ_ENROLLEE_INFO;
 216 #endif /* CONFIG_WPS */
 217         struct wpa_driver_scan_params params;
 218         size_t max_ssids;
 219
 220         if (wpa_s->disconnected && !wpa_s->scan_req) {
 221                 wpa_supplicant_set_state(wpa_s, WPA_DISCONNECTED);
 222                 return;
 223         }
 224
 225         if (!wpa_supplicant_enabled_networks(wpa_s->conf) &&
 226             !wpa_s->scan_req) {
 227                 wpa_printf(MSG_DEBUG, "No enabled networks - do not scan");
 228                 wpa_supplicant_set_state(wpa_s, WPA_INACTIVE);
 229                 return;
 230         }
 231
 232         if (wpa_s->conf->ap_scan != 0 &&
 233             (wpa_s->drv_flags & WPA_DRIVER_FLAGS_WIRED)) {
 234                 wpa_printf(MSG_DEBUG, "Using wired authentication - "
 235                            "overriding ap_scan configuration");
 236                 wpa_s->conf->ap_scan = 0;
 237                 wpas_notify_ap_scan_changed(wpa_s);
 238         }
 239
 240         if (wpa_s->conf->ap_scan == 0) {
 241                 wpa_supplicant_gen_assoc_event(wpa_s);
 242                 return;
 243         }
 244
 245         if ((wpa_s->drv_flags & WPA_DRIVER_FLAGS_USER_SPACE_MLME) ||
 246             wpa_s->conf->ap_scan == 2)
 247                 max_ssids = 1;
 248         else {
 249                 max_ssids = wpa_s->max_scan_ssids;
 250                 if (max_ssids > WPAS_MAX_SCAN_SSIDS)
 251                         max_ssids = WPAS_MAX_SCAN_SSIDS;
 252         }
 253
 254 #ifdef CONFIG_WPS
 255         wps = wpas_wps_in_use(wpa_s->conf, &req_type);
 256 #endif /* CONFIG_WPS */
 257
 258         if (wpa_s->scan_res_tried == 0 && wpa_s->conf->ap_scan == 1 &&
 259             !(wpa_s->drv_flags & WPA_DRIVER_FLAGS_USER_SPACE_MLME) &&
 260             wps != 2) {
 261                 wpa_s->scan_res_tried++;
 262                 wpa_printf(MSG_DEBUG, "Trying to get current scan results "
 263                            "first without requesting a new scan to speed up "
 264                            "initial association");
 265                 wpa_supplicant_event(wpa_s, EVENT_SCAN_RESULTS, NULL);
 266                 return;
 267         }
 268
 269         scan_req = wpa_s->scan_req;
 270         wpa_s->scan_req = 0;
 271
 272         os_memset(&params, 0, sizeof(params));
 273
 274         if (wpa_s->wpa_state == WPA_DISCONNECTED ||
 275             wpa_s->wpa_state == WPA_INACTIVE)
 276                 wpa_supplicant_set_state(wpa_s, WPA_SCANNING);
 277
 278         /* Find the starting point from which to continue scanning */
 279         ssid = wpa_s->conf->ssid;
 280         if (wpa_s->prev_scan_ssid != WILDCARD_SSID_SCAN) {
 281                 while (ssid) {
 282                         if (ssid == wpa_s->prev_scan_ssid) {
 283                                 ssid = ssid->next;
 284                                 break;
 285                         }
 286                         ssid = ssid->next;
 287                 }
 288         }
 289
 290         if (scan_req != 2 && wpa_s->conf->ap_scan == 2) {
 291                 wpa_supplicant_assoc_try(wpa_s, ssid);
 292                 return;
 293         } else if (wpa_s->conf->ap_scan == 2) {
 294                 /*
 295                  * User-initiated scan request in ap_scan == 2; scan with
 296                  * wildcard SSID.
 297                  */
 298                 ssid = NULL;
 299         } else {
 300                 struct wpa_ssid *start = ssid, *tssid;
 301                 int freqs_set = 0;
 302                 if (ssid == NULL && max_ssids > 1)
 303                         ssid = wpa_s->conf->ssid;
 304                 while (ssid) {
 305                         if (!ssid->disabled && ssid->scan_ssid) {
 306                                 wpa_hexdump_ascii(MSG_DEBUG, "Scan SSID",
 307                                                   ssid->ssid, ssid->ssid_len);
 308                                 params.ssids[params.num_ssids].ssid =
 309                                         ssid->ssid;
 310                                 params.ssids[params.num_ssids].ssid_len =
 311                                         ssid->ssid_len;
 312                                 params.num_ssids++;
 313                                 if (params.num_ssids + 1 >= max_ssids)
 314                                         break;
 315                         }
 316                         ssid = ssid->next;
 317                         if (ssid == start)
 318                                 break;
 319                         if (ssid == NULL && max_ssids > 1 &&
 320                             start != wpa_s->conf->ssid)
 321                                 ssid = wpa_s->conf->ssid;
 322                 }
 323
 324                 for (tssid = wpa_s->conf->ssid; tssid; tssid = tssid->next) {
 325                         if (tssid->disabled)
 326                                 continue;
 327                         if ((params.freqs || !freqs_set) && tssid->scan_freq) {
 328                                 int_array_concat(&params.freqs,
 329                                                  tssid->scan_freq);
 330                         } else {
 331                                 os_free(params.freqs);
 332                                 params.freqs = NULL;
 333                         }
 334                         freqs_set = 1;
 335                 }
 336                 int_array_sort_unique(params.freqs);
 337         }
 338
 339         if (ssid) {
 340                 wpa_s->prev_scan_ssid = ssid;
 341                 if (max_ssids > 1) {
 342                         wpa_printf(MSG_DEBUG, "Include wildcard SSID in the "
 343                                    "scan request");
 344                         params.num_ssids++;
 345                 }
 346                 wpa_printf(MSG_DEBUG, "Starting AP scan for specific SSID(s)");
 347         } else {
 348                 wpa_s->prev_scan_ssid = WILDCARD_SSID_SCAN;
 349                 params.num_ssids++;
 350                 wpa_printf(MSG_DEBUG, "Starting AP scan for wildcard SSID");
 351         }
 352
 353 #ifdef CONFIG_WPS
 354         if (wps) {
 355                 wps_ie = wps_build_probe_req_ie(wps == 2, &wpa_s->wps->dev,
 356                                                 wpa_s->wps->uuid, req_type);
 357                 if (wps_ie) {
 358                         params.extra_ies = wpabuf_head(wps_ie);
 359                         params.extra_ies_len = wpabuf_len(wps_ie);
 360                 }
 361         }
 362 #endif /* CONFIG_WPS */
 363
 364         ret = wpa_supplicant_trigger_scan(wpa_s, &params);
 365
 366         wpabuf_free(wps_ie);
 367         os_free(params.freqs);
 368
 369         if (ret) {
 370                 wpa_printf(MSG_WARNING, "Failed to initiate AP scan.");
 371                 wpa_supplicant_req_scan(wpa_s, 10, 0);
 372         } else
 373                 wpa_s->scan_runs++;
 374 }
 375
 376
 377 /**
 378  * wpa_supplicant_req_scan - Schedule a scan for neighboring access points
 379  * @wpa_s: Pointer to wpa_supplicant data
 380  * @sec: Number of seconds after which to scan
 381  * @usec: Number of microseconds after which to scan
 382  *
 383  * This function is used to schedule a scan for neighboring access points after
 384  * the specified time.
 385  */
 386 void wpa_supplicant_req_scan(struct wpa_supplicant *wpa_s, int sec, int usec)
 387 {
 388         /* If there's at least one network that should be specifically scanned
 389          * then don't cancel the scan and reschedule.  Some drivers do
 390          * background scanning which generates frequent scan results, and that
 391          * causes the specific SSID scan to get continually pushed back and
 392          * never happen, which causes hidden APs to never get probe-scanned.
 393          */
 394         if (eloop_is_timeout_registered(wpa_supplicant_scan, wpa_s, NULL) &&
 395             wpa_s->conf->ap_scan == 1) {
 396                 struct wpa_ssid *ssid = wpa_s->conf->ssid;
 397
 398                 while (ssid) {
 399                         if (!ssid->disabled && ssid->scan_ssid)
 400                                 break;
 401                         ssid = ssid->next;
 402                 }
 403                 if (ssid) {
 404                         wpa_msg(wpa_s, MSG_DEBUG, "Not rescheduling scan to "
 405                                 "ensure that specific SSID scans occur");
 406                         return;
 407                 }
 408         }
 409
 410         wpa_msg(wpa_s, MSG_DEBUG, "Setting scan request: %d sec %d usec",
 411                 sec, usec);
 412         eloop_cancel_timeout(wpa_supplicant_scan, wpa_s, NULL);
 413         eloop_register_timeout(sec, usec, wpa_supplicant_scan, wpa_s, NULL);
 414 }
 415
 416
 417 /**
 418  * wpa_supplicant_cancel_scan - Cancel a scheduled scan request
 419  * @wpa_s: Pointer to wpa_supplicant data
 420  *
 421  * This function is used to cancel a scan request scheduled with
 422  * wpa_supplicant_req_scan().
 423  */
 424 void wpa_supplicant_cancel_scan(struct wpa_supplicant *wpa_s)
 425 {
 426         wpa_msg(wpa_s, MSG_DEBUG, "Cancelling scan request");
 427         eloop_cancel_timeout(wpa_supplicant_scan, wpa_s, NULL);
 428 }
 429
 430
 431 void wpa_supplicant_notify_scanning(struct wpa_supplicant *wpa_s,
 432                                     int scanning)
 433 {
 434         if (wpa_s->scanning != scanning) {
 435                 wpa_s->scanning = scanning;
 436                 wpas_notify_scanning(wpa_s);
 437         }
 438 }
 439
 440
 441 static int wpa_scan_get_max_rate(const struct wpa_scan_res *res)
 442 {
 443         int rate = 0;
 444         const u8 *ie;
 445         int i;
 446
 447         ie = wpa_scan_get_ie(res, WLAN_EID_SUPP_RATES);
 448         for (i = 0; ie && i < ie[1]; i++) {
 449                 if ((ie[i + 2] & 0x7f) > rate)
 450                         rate = ie[i + 2] & 0x7f;
 451         }
 452
 453         ie = wpa_scan_get_ie(res, WLAN_EID_EXT_SUPP_RATES);
 454         for (i = 0; ie && i < ie[1]; i++) {
 455                 if ((ie[i + 2] & 0x7f) > rate)
 456                         rate = ie[i + 2] & 0x7f;
 457         }
 458
 459         return rate;
 460 }
 461
 462
 463 const u8 * wpa_scan_get_vendor_ie(const struct wpa_scan_res *res,
 464                                   u32 vendor_type)
 465 {
 466         const u8 *end, *pos;
 467
 468         pos = (const u8 *) (res + 1);
 469         end = pos + res->ie_len;
 470
 471         while (pos + 1 < end) {
 472                 if (pos + 2 + pos[1] > end)
 473                         break;
 474                 if (pos[0] == WLAN_EID_VENDOR_SPECIFIC && pos[1] >= 4 &&
 475                     vendor_type == WPA_GET_BE32(&pos[2]))
 476                         return pos;
 477                 pos += 2 + pos[1];
 478         }
 479
 480         return NULL;
 481 }
 482
 483
 484 struct wpabuf * wpa_scan_get_vendor_ie_multi(const struct wpa_scan_res *res,
 485                                              u32 vendor_type)
 486 {
 487         struct wpabuf *buf;
 488         const u8 *end, *pos;
 489
 490         buf = wpabuf_alloc(res->ie_len);
 491         if (buf == NULL)
 492                 return NULL;
 493
 494         pos = (const u8 *) (res + 1);
 495         end = pos + res->ie_len;
 496
 497         while (pos + 1 < end) {
 498                 if (pos + 2 + pos[1] > end)
 499                         break;
 500                 if (pos[0] == WLAN_EID_VENDOR_SPECIFIC && pos[1] >= 4 &&
 501                     vendor_type == WPA_GET_BE32(&pos[2]))
 502                         wpabuf_put_data(buf, pos + 2 + 4, pos[1] - 4);
 503                 pos += 2 + pos[1];
 504         }
 505
 506         if (wpabuf_len(buf) == 0) {
 507                 wpabuf_free(buf);
 508                 buf = NULL;
 509         }
 510
 511         return buf;
 512 }
 513
 514
 515 /* Compare function for sorting scan results. Return >0 if @b is considered
 516  * better. */
 517 static int wpa_scan_result_compar(const void *a, const void *b)
 518 {
 519         struct wpa_scan_res **_wa = (void *) a;
 520         struct wpa_scan_res **_wb = (void *) b;
 521         struct wpa_scan_res *wa = *_wa;
 522         struct wpa_scan_res *wb = *_wb;
 523         int wpa_a, wpa_b, maxrate_a, maxrate_b;
 524
 525         /* WPA/WPA2 support preferred */
 526         wpa_a = wpa_scan_get_vendor_ie(wa, WPA_IE_VENDOR_TYPE) != NULL ||
 527                 wpa_scan_get_ie(wa, WLAN_EID_RSN) != NULL;
 528         wpa_b = wpa_scan_get_vendor_ie(wb, WPA_IE_VENDOR_TYPE) != NULL ||
 529                 wpa_scan_get_ie(wb, WLAN_EID_RSN) != NULL;
 530
 531         if (wpa_b && !wpa_a)
 532                 return 1;
 533         if (!wpa_b && wpa_a)
 534                 return -1;
 535
 536         /* privacy support preferred */
 537         if ((wa->caps & IEEE80211_CAP_PRIVACY) == 0 &&
 538             (wb->caps & IEEE80211_CAP_PRIVACY))
 539                 return 1;
 540         if ((wa->caps & IEEE80211_CAP_PRIVACY) &&
 541             (wb->caps & IEEE80211_CAP_PRIVACY) == 0)
 542                 return -1;
 543
 544         /* best/max rate preferred if signal level close enough XXX */
 545         if ((wa->level && wb->level && abs(wb->level - wa->level) < 5) ||
 546             (wa->qual && wb->qual && abs(wb->qual - wa->qual) < 10)) {
 547                 maxrate_a = wpa_scan_get_max_rate(wa);
 548                 maxrate_b = wpa_scan_get_max_rate(wb);
 549                 if (maxrate_a != maxrate_b)
 550                         return maxrate_b - maxrate_a;
 551         }
 552
 553         /* use freq for channel preference */
 554
 555         /* all things being equal, use signal level; if signal levels are
 556          * identical, use quality values since some drivers may only report
 557          * that value and leave the signal level zero */
 558         if (wb->level == wa->level)
 559                 return wb->qual - wa->qual;
 560         return wb->level - wa->level;
 561 }
 562
 563
 564 /**
 565  * wpa_supplicant_get_scan_results - Get scan results
 566  * @wpa_s: Pointer to wpa_supplicant data
 567  * @info: Information about what was scanned or %NULL if not available
 568  * @new_scan: Whether a new scan was performed
 569  * Returns: Scan results, %NULL on failure
 570  *
 571  * This function request the current scan results from the driver and updates
 572  * the local BSS list wpa_s->bss. The caller is responsible for freeing the
 573  * results with wpa_scan_results_free().
 574  */
 575 struct wpa_scan_results *
 576 wpa_supplicant_get_scan_results(struct wpa_supplicant *wpa_s,
 577                                 struct scan_info *info, int new_scan)
 578 {
 579         struct wpa_scan_results *scan_res;
 580         size_t i;
 581
 582         if (wpa_s->drv_flags & WPA_DRIVER_FLAGS_USER_SPACE_MLME)
 583                 scan_res = ieee80211_sta_get_scan_results(wpa_s);
 584         else
 585                 scan_res = wpa_drv_get_scan_results2(wpa_s);
 586         if (scan_res == NULL) {
 587                 wpa_printf(MSG_DEBUG, "Failed to get scan results");
 588                 return NULL;
 589         }
 590
 591         qsort(scan_res->res, scan_res->num, sizeof(struct wpa_scan_res *),
 592               wpa_scan_result_compar);
 593
 594         wpa_bss_update_start(wpa_s);
 595         for (i = 0; i < scan_res->num; i++)
 596                 wpa_bss_update_scan_res(wpa_s, scan_res->res[i]);
 597         wpa_bss_update_end(wpa_s, info, new_scan);
 598
 599         return scan_res;
 600 }
 601
 602
 603 int wpa_supplicant_update_scan_results(struct wpa_supplicant *wpa_s)
 604 {
 605         struct wpa_scan_results *scan_res;
 606         scan_res = wpa_supplicant_get_scan_results(wpa_s, NULL, 0);
 607         if (scan_res == NULL)
 608                 return -1;
 609         wpa_scan_results_free(scan_res);
 610
 611         return 0;
 612 }