wpa_supplicant/bgscan_learn.c

   1 /*
   2  * WPA Supplicant - background scan and roaming module: learn
   3  * Copyright (c) 2009-2010, Jouni Malinen <j@w1.fi>
   4  *
   5  * This software may be distributed under the terms of the BSD license.
   6  * See README for more details.
   7  */
   8
   9 #include "includes.h"
  10
  11 #include "common.h"
  12 #include "eloop.h"
  13 #include "list.h"
  14 #include "common/ieee802_11_defs.h"
  15 #include "drivers/driver.h"
  16 #include "config_ssid.h"
  17 #include "wpa_supplicant_i.h"
  18 #include "driver_i.h"
  19 #include "scan.h"
  20 #include "bgscan.h"
  21
  22 struct bgscan_learn_bss {
  23         struct dl_list list;
  24         u8 bssid[ETH_ALEN];
  25         int freq;
  26         u8 *neigh; /* num_neigh * ETH_ALEN buffer */
  27         size_t num_neigh;
  28 };
  29
  30 struct bgscan_learn_data {
  31         struct wpa_supplicant *wpa_s;
  32         const struct wpa_ssid *ssid;
  33         int scan_interval;
  34         int signal_threshold;
  35         int short_interval; /* use if signal < threshold */
  36         int long_interval; /* use if signal > threshold */
  37         struct os_time last_bgscan;
  38         char *fname;
  39         struct dl_list bss;
  40         int *supp_freqs;
  41         int probe_idx;
  42 };
  43
  44
  45 static void bss_free(struct bgscan_learn_bss *bss)
  46 {
  47         os_free(bss->neigh);
  48         os_free(bss);
  49 }
  50
  51
  52 static int bssid_in_array(u8 *array, size_t array_len, const u8 *bssid)
  53 {
  54         size_t i;
  55
  56         if (array == NULL || array_len == 0)
  57                 return 0;
  58
  59         for (i = 0; i < array_len; i++) {
  60                 if (os_memcmp(array + i * ETH_ALEN, bssid, ETH_ALEN) == 0)
  61                         return 1;
  62         }
  63
  64         return 0;
  65 }
  66
  67
  68 static void bgscan_learn_add_neighbor(struct bgscan_learn_bss *bss,
  69                                       const u8 *bssid)
  70 {
  71         u8 *n;
  72
  73         if (os_memcmp(bss->bssid, bssid, ETH_ALEN) == 0)
  74                 return;
  75         if (bssid_in_array(bss->neigh, bss->num_neigh, bssid))
  76                 return;
  77
  78         n = os_realloc_array(bss->neigh, bss->num_neigh + 1, ETH_ALEN);
  79         if (n == NULL)
  80                 return;
  81
  82         os_memcpy(n + bss->num_neigh * ETH_ALEN, bssid, ETH_ALEN);
  83         bss->neigh = n;
  84         bss->num_neigh++;
  85 }
  86
  87
  88 static struct bgscan_learn_bss * bgscan_learn_get_bss(
  89         struct bgscan_learn_data *data, const u8 *bssid)
  90 {
  91         struct bgscan_learn_bss *bss;
  92
  93         dl_list_for_each(bss, &data->bss, struct bgscan_learn_bss, list) {
  94                 if (os_memcmp(bss->bssid, bssid, ETH_ALEN) == 0)
  95                         return bss;
  96         }
  97         return NULL;
  98 }
  99
 100
 101 static int bgscan_learn_load(struct bgscan_learn_data *data)
 102 {
 103         FILE *f;
 104         char buf[128];
 105         struct bgscan_learn_bss *bss;
 106
 107         if (data->fname == NULL)
 108                 return 0;
 109
 110         f = fopen(data->fname, "r");
 111         if (f == NULL)
 112                 return 0;
 113
 114         wpa_printf(MSG_DEBUG, "bgscan learn: Loading data from %s",
 115                    data->fname);
 116
 117         if (fgets(buf, sizeof(buf), f) == NULL ||
 118             os_strncmp(buf, "wpa_supplicant-bgscan-learn\n", 28) != 0) {
 119                 wpa_printf(MSG_INFO, "bgscan learn: Invalid data file %s",
 120                            data->fname);
 121                 fclose(f);
 122                 return -1;
 123         }
 124
 125         while (fgets(buf, sizeof(buf), f)) {
 126                 if (os_strncmp(buf, "BSS ", 4) == 0) {
 127                         bss = os_zalloc(sizeof(*bss));
 128                         if (!bss)
 129                                 continue;
 130                         if (hwaddr_aton(buf + 4, bss->bssid) < 0) {
 131                                 bss_free(bss);
 132                                 continue;
 133                         }
 134                         bss->freq = atoi(buf + 4 + 18);
 135                         dl_list_add(&data->bss, &bss->list);
 136                         wpa_printf(MSG_DEBUG, "bgscan learn: Loaded BSS "
 137                                    "entry: " MACSTR " freq=%d",
 138                                    MAC2STR(bss->bssid), bss->freq);
 139                 }
 140
 141                 if (os_strncmp(buf, "NEIGHBOR ", 9) == 0) {
 142                         u8 addr[ETH_ALEN];
 143
 144                         if (hwaddr_aton(buf + 9, addr) < 0)
 145                                 continue;
 146                         bss = bgscan_learn_get_bss(data, addr);
 147                         if (bss == NULL)
 148                                 continue;
 149                         if (hwaddr_aton(buf + 9 + 18, addr) < 0)
 150                                 continue;
 151
 152                         bgscan_learn_add_neighbor(bss, addr);
 153                 }
 154         }
 155
 156         fclose(f);
 157         return 0;
 158 }
 159
 160
 161 static void bgscan_learn_save(struct bgscan_learn_data *data)
 162 {
 163         FILE *f;
 164         struct bgscan_learn_bss *bss;
 165
 166         if (data->fname == NULL)
 167                 return;
 168
 169         wpa_printf(MSG_DEBUG, "bgscan learn: Saving data to %s",
 170                    data->fname);
 171
 172         f = fopen(data->fname, "w");
 173         if (f == NULL)
 174                 return;
 175         fprintf(f, "wpa_supplicant-bgscan-learn\n");
 176
 177         dl_list_for_each(bss, &data->bss, struct bgscan_learn_bss, list) {
 178                 fprintf(f, "BSS " MACSTR " %d\n",
 179                         MAC2STR(bss->bssid), bss->freq);
 180         }
 181
 182         dl_list_for_each(bss, &data->bss, struct bgscan_learn_bss, list) {
 183                 size_t i;
 184                 for (i = 0; i < bss->num_neigh; i++) {
 185                         fprintf(f, "NEIGHBOR " MACSTR " " MACSTR "\n",
 186                                 MAC2STR(bss->bssid),
 187                                 MAC2STR(bss->neigh + i * ETH_ALEN));
 188                 }
 189         }
 190
 191         fclose(f);
 192 }
 193
 194
 195 static int in_array(int *array, int val)
 196 {
 197         int i;
 198
 199         if (array == NULL)
 200                 return 0;
 201
 202         for (i = 0; array[i]; i++) {
 203                 if (array[i] == val)
 204                         return 1;
 205         }
 206
 207         return 0;
 208 }
 209
 210
 211 static int * bgscan_learn_get_freqs(struct bgscan_learn_data *data,
 212                                     size_t *count)
 213 {
 214         struct bgscan_learn_bss *bss;
 215         int *freqs = NULL, *n;
 216
 217         *count = 0;
 218
 219         dl_list_for_each(bss, &data->bss, struct bgscan_learn_bss, list) {
 220                 if (in_array(freqs, bss->freq))
 221                         continue;
 222                 n = os_realloc_array(freqs, *count + 2, sizeof(int));
 223                 if (n == NULL)
 224                         return freqs;
 225                 freqs = n;
 226                 freqs[*count] = bss->freq;
 227                 (*count)++;
 228                 freqs[*count] = 0;
 229         }
 230
 231         return freqs;
 232 }
 233
 234
 235 static int * bgscan_learn_get_probe_freq(struct bgscan_learn_data *data,
 236                                          int *freqs, size_t count)
 237 {
 238         int idx, *n;
 239
 240         if (data->supp_freqs == NULL)
 241                 return freqs;
 242
 243         idx = data->probe_idx + 1;
 244         while (idx != data->probe_idx) {
 245                 if (data->supp_freqs[idx] == 0) {
 246                         if (data->probe_idx == 0)
 247                                 break;
 248                         idx = 0;
 249                 }
 250                 if (!in_array(freqs, data->supp_freqs[idx])) {
 251                         wpa_printf(MSG_DEBUG, "bgscan learn: Probe new freq "
 252                                    "%u", data->supp_freqs[idx]);
 253                         data->probe_idx = idx;
 254                         n = os_realloc_array(freqs, count + 2, sizeof(int));
 255                         if (n == NULL)
 256                                 return freqs;
 257                         freqs = n;
 258                         freqs[count] = data->supp_freqs[idx];
 259                         count++;
 260                         freqs[count] = 0;
 261                         break;
 262                 }
 263
 264                 idx++;
 265         }
 266
 267         return freqs;
 268 }
 269
 270
 271 static void bgscan_learn_timeout(void *eloop_ctx, void *timeout_ctx)
 272 {
 273         struct bgscan_learn_data *data = eloop_ctx;
 274         struct wpa_supplicant *wpa_s = data->wpa_s;
 275         struct wpa_driver_scan_params params;
 276         int *freqs = NULL;
 277         size_t count, i;
 278         char msg[100], *pos;
 279
 280         os_memset(&params, 0, sizeof(params));
 281         params.num_ssids = 1;
 282         params.ssids[0].ssid = data->ssid->ssid;
 283         params.ssids[0].ssid_len = data->ssid->ssid_len;
 284         if (data->ssid->scan_freq)
 285                 params.freqs = data->ssid->scan_freq;
 286         else {
 287                 freqs = bgscan_learn_get_freqs(data, &count);
 288                 wpa_printf(MSG_DEBUG, "bgscan learn: BSSes in this ESS have "
 289                            "been seen on %u channels", (unsigned int) count);
 290                 freqs = bgscan_learn_get_probe_freq(data, freqs, count);
 291
 292                 msg[0] = '\0';
 293                 pos = msg;
 294                 for (i = 0; freqs && freqs[i]; i++) {
 295                         int ret;
 296                         ret = os_snprintf(pos, msg + sizeof(msg) - pos, " %d",
 297                                           freqs[i]);
 298                         if (ret < 0 || ret >= msg + sizeof(msg) - pos)
 299                                 break;
 300                         pos += ret;
 301                 }
 302                 pos[0] = '\0';
 303                 wpa_printf(MSG_DEBUG, "bgscan learn: Scanning frequencies:%s",
 304                            msg);
 305                 params.freqs = freqs;
 306         }
 307
 308         wpa_printf(MSG_DEBUG, "bgscan learn: Request a background scan");
 309         if (wpa_supplicant_trigger_scan(wpa_s, &params)) {
 310                 wpa_printf(MSG_DEBUG, "bgscan learn: Failed to trigger scan");
 311                 eloop_register_timeout(data->scan_interval, 0,
 312                                        bgscan_learn_timeout, data, NULL);
 313         } else
 314                 os_get_time(&data->last_bgscan);
 315         os_free(freqs);
 316 }
 317
 318
 319 static int bgscan_learn_get_params(struct bgscan_learn_data *data,
 320                                    const char *params)
 321 {
 322         const char *pos;
 323
 324         if (params == NULL)
 325                 return 0;
 326
 327         data->short_interval = atoi(params);
 328
 329         pos = os_strchr(params, ':');
 330         if (pos == NULL)
 331                 return 0;
 332         pos++;
 333         data->signal_threshold = atoi(pos);
 334         pos = os_strchr(pos, ':');
 335         if (pos == NULL) {
 336                 wpa_printf(MSG_ERROR, "bgscan learn: Missing scan interval "
 337                            "for high signal");
 338                 return -1;
 339         }
 340         pos++;
 341         data->long_interval = atoi(pos);
 342         pos = os_strchr(pos, ':');
 343         if (pos) {
 344                 pos++;
 345                 data->fname = os_strdup(pos);
 346         }
 347
 348         return 0;
 349 }
 350
 351
 352 static int * bgscan_learn_get_supp_freqs(struct wpa_supplicant *wpa_s)
 353 {
 354         struct hostapd_hw_modes *modes;
 355         int i, j, *freqs = NULL, *n;
 356         size_t count = 0;
 357
 358         modes = wpa_s->hw.modes;
 359         if (modes == NULL)
 360                 return NULL;
 361
 362         for (i = 0; i < wpa_s->hw.num_modes; i++) {
 363                 for (j = 0; j < modes[i].num_channels; j++) {
 364                         if (modes[i].channels[j].flag & HOSTAPD_CHAN_DISABLED)
 365                                 continue;
 366                         /* some hw modes (e.g. 11b & 11g) contain same freqs */
 367                         if (in_array(freqs, modes[i].channels[j].freq))
 368                                 continue;
 369                         n = os_realloc_array(freqs, count + 2, sizeof(int));
 370                         if (n == NULL)
 371                                 continue;
 372
 373                         freqs = n;
 374                         freqs[count] = modes[i].channels[j].freq;
 375                         count++;
 376                         freqs[count] = 0;
 377                 }
 378         }
 379
 380         return freqs;
 381 }
 382
 383
 384 static void * bgscan_learn_init(struct wpa_supplicant *wpa_s,
 385                                 const char *params,
 386                                 const struct wpa_ssid *ssid)
 387 {
 388         struct bgscan_learn_data *data;
 389
 390         data = os_zalloc(sizeof(*data));
 391         if (data == NULL)
 392                 return NULL;
 393         dl_list_init(&data->bss);
 394         data->wpa_s = wpa_s;
 395         data->ssid = ssid;
 396         if (bgscan_learn_get_params(data, params) < 0) {
 397                 os_free(data->fname);
 398                 os_free(data);
 399                 return NULL;
 400         }
 401         if (data->short_interval <= 0)
 402                 data->short_interval = 30;
 403         if (data->long_interval <= 0)
 404                 data->long_interval = 30;
 405
 406         if (bgscan_learn_load(data) < 0) {
 407                 os_free(data->fname);
 408                 os_free(data);
 409                 return NULL;
 410         }
 411
 412         wpa_printf(MSG_DEBUG, "bgscan learn: Signal strength threshold %d  "
 413                    "Short bgscan interval %d  Long bgscan interval %d",
 414                    data->signal_threshold, data->short_interval,
 415                    data->long_interval);
 416
 417         if (data->signal_threshold &&
 418             wpa_drv_signal_monitor(wpa_s, data->signal_threshold, 4) < 0) {
 419                 wpa_printf(MSG_ERROR, "bgscan learn: Failed to enable "
 420                            "signal strength monitoring");
 421         }
 422
 423         data->supp_freqs = bgscan_learn_get_supp_freqs(wpa_s);
 424         data->scan_interval = data->short_interval;
 425         eloop_register_timeout(data->scan_interval, 0, bgscan_learn_timeout,
 426                                data, NULL);
 427
 428         /*
 429          * This function is called immediately after an association, so it is
 430          * reasonable to assume that a scan was completed recently. This makes
 431          * us skip an immediate new scan in cases where the current signal
 432          * level is below the bgscan threshold.
 433          */
 434         os_get_time(&data->last_bgscan);
 435
 436         return data;
 437 }
 438
 439
 440 static void bgscan_learn_deinit(void *priv)
 441 {
 442         struct bgscan_learn_data *data = priv;
 443         struct bgscan_learn_bss *bss, *n;
 444
 445         bgscan_learn_save(data);
 446         eloop_cancel_timeout(bgscan_learn_timeout, data, NULL);
 447         if (data->signal_threshold)
 448                 wpa_drv_signal_monitor(data->wpa_s, 0, 0);
 449         os_free(data->fname);
 450         dl_list_for_each_safe(bss, n, &data->bss, struct bgscan_learn_bss,
 451                               list) {
 452                 dl_list_del(&bss->list);
 453                 bss_free(bss);
 454         }
 455         os_free(data->supp_freqs);
 456         os_free(data);
 457 }
 458
 459
 460 static int bgscan_learn_bss_match(struct bgscan_learn_data *data,
 461                                   struct wpa_scan_res *bss)
 462 {
 463         const u8 *ie;
 464
 465         ie = wpa_scan_get_ie(bss, WLAN_EID_SSID);
 466         if (ie == NULL)
 467                 return 0;
 468
 469         if (data->ssid->ssid_len != ie[1] ||
 470             os_memcmp(data->ssid->ssid, ie + 2, ie[1]) != 0)
 471                 return 0; /* SSID mismatch */
 472
 473         return 1;
 474 }
 475
 476
 477 static int bgscan_learn_notify_scan(void *priv,
 478                                     struct wpa_scan_results *scan_res)
 479 {
 480         struct bgscan_learn_data *data = priv;
 481         size_t i, j;
 482 #define MAX_BSS 50
 483         u8 bssid[MAX_BSS * ETH_ALEN];
 484         size_t num_bssid = 0;
 485
 486         wpa_printf(MSG_DEBUG, "bgscan learn: scan result notification");
 487
 488         eloop_cancel_timeout(bgscan_learn_timeout, data, NULL);
 489         eloop_register_timeout(data->scan_interval, 0, bgscan_learn_timeout,
 490                                data, NULL);
 491
 492         for (i = 0; i < scan_res->num; i++) {
 493                 struct wpa_scan_res *res = scan_res->res[i];
 494                 if (!bgscan_learn_bss_match(data, res))
 495                         continue;
 496
 497                 if (num_bssid < MAX_BSS) {
 498                         os_memcpy(bssid + num_bssid * ETH_ALEN, res->bssid,
 499                                   ETH_ALEN);
 500                         num_bssid++;
 501                 }
 502         }
 503         wpa_printf(MSG_DEBUG, "bgscan learn: %u matching BSSes in scan "
 504                    "results", (unsigned int) num_bssid);
 505
 506         for (i = 0; i < scan_res->num; i++) {
 507                 struct wpa_scan_res *res = scan_res->res[i];
 508                 struct bgscan_learn_bss *bss;
 509
 510                 if (!bgscan_learn_bss_match(data, res))
 511                         continue;
 512
 513                 bss = bgscan_learn_get_bss(data, res->bssid);
 514                 if (bss && bss->freq != res->freq) {
 515                         wpa_printf(MSG_DEBUG, "bgscan learn: Update BSS "
 516                            MACSTR " freq %d -> %d",
 517                                    MAC2STR(res->bssid), bss->freq, res->freq);
 518                         bss->freq = res->freq;
 519                 } else if (!bss) {
 520                         wpa_printf(MSG_DEBUG, "bgscan learn: Add BSS " MACSTR
 521                                    " freq=%d", MAC2STR(res->bssid), res->freq);
 522                         bss = os_zalloc(sizeof(*bss));
 523                         if (!bss)
 524                                 continue;
 525                         os_memcpy(bss->bssid, res->bssid, ETH_ALEN);
 526                         bss->freq = res->freq;
 527                         dl_list_add(&data->bss, &bss->list);
 528                 }
 529
 530                 for (j = 0; j < num_bssid; j++) {
 531                         u8 *addr = bssid + j * ETH_ALEN;
 532                         bgscan_learn_add_neighbor(bss, addr);
 533                 }
 534         }
 535
 536         /*
 537          * A more advanced bgscan could process scan results internally, select
 538          * the BSS and request roam if needed. This sample uses the existing
 539          * BSS/ESS selection routine. Change this to return 1 if selection is
 540          * done inside the bgscan module.
 541          */
 542
 543         return 0;
 544 }
 545
 546
 547 static void bgscan_learn_notify_beacon_loss(void *priv)
 548 {
 549         wpa_printf(MSG_DEBUG, "bgscan learn: beacon loss");
 550         /* TODO: speed up background scanning */
 551 }
 552
 553
 554 static void bgscan_learn_notify_signal_change(void *priv, int above,
 555                                               int current_signal,
 556                                               int current_noise,
 557                                               int current_txrate)
 558 {
 559         struct bgscan_learn_data *data = priv;
 560         int scan = 0;
 561         struct os_time now;
 562
 563         if (data->short_interval == data->long_interval ||
 564             data->signal_threshold == 0)
 565                 return;
 566
 567         wpa_printf(MSG_DEBUG, "bgscan learn: signal level changed "
 568                    "(above=%d current_signal=%d current_noise=%d "
 569                    "current_txrate=%d)", above, current_signal,
 570                    current_noise, current_txrate);
 571         if (data->scan_interval == data->long_interval && !above) {
 572                 wpa_printf(MSG_DEBUG, "bgscan learn: Start using short bgscan "
 573                            "interval");
 574                 data->scan_interval = data->short_interval;
 575                 os_get_time(&now);
 576                 if (now.sec > data->last_bgscan.sec + 1)
 577                         scan = 1;
 578         } else if (data->scan_interval == data->short_interval && above) {
 579                 wpa_printf(MSG_DEBUG, "bgscan learn: Start using long bgscan "
 580                            "interval");
 581                 data->scan_interval = data->long_interval;
 582                 eloop_cancel_timeout(bgscan_learn_timeout, data, NULL);
 583                 eloop_register_timeout(data->scan_interval, 0,
 584                                        bgscan_learn_timeout, data, NULL);
 585         } else if (!above) {
 586                 /*
 587                  * Signal dropped further 4 dB. Request a new scan if we have
 588                  * not yet scanned in a while.
 589                  */
 590                 os_get_time(&now);
 591                 if (now.sec > data->last_bgscan.sec + 10)
 592                         scan = 1;
 593         }
 594
 595         if (scan) {
 596                 wpa_printf(MSG_DEBUG, "bgscan learn: Trigger immediate scan");
 597                 eloop_cancel_timeout(bgscan_learn_timeout, data, NULL);
 598                 eloop_register_timeout(0, 0, bgscan_learn_timeout, data, NULL);
 599         }
 600 }
 601
 602
 603 const struct bgscan_ops bgscan_learn_ops = {
 604         .name = "learn",
 605         .init = bgscan_learn_init,
 606         .deinit = bgscan_learn_deinit,
 607         .notify_scan = bgscan_learn_notify_scan,
 608         .notify_beacon_loss = bgscan_learn_notify_beacon_loss,
 609         .notify_signal_change = bgscan_learn_notify_signal_change,
 610 };