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 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 "list.h"
  20 #include "common/ieee802_11_defs.h"
  21 #include "drivers/driver.h"
  22 #include "config_ssid.h"
  23 #include "wpa_supplicant_i.h"
  24 #include "driver_i.h"
  25 #include "scan.h"
  26 #include "bgscan.h"
  27
  28 struct bgscan_learn_bss {
  29         struct dl_list list;
  30         u8 bssid[ETH_ALEN];
  31         int freq;
  32         u8 *neigh; /* num_neigh * ETH_ALEN buffer */
  33         size_t num_neigh;
  34 };
  35
  36 struct bgscan_learn_data {
  37         struct wpa_supplicant *wpa_s;
  38         const struct wpa_ssid *ssid;
  39         int scan_interval;
  40         int signal_threshold;
  41         int short_interval; /* use if signal < threshold */
  42         int long_interval; /* use if signal > threshold */
  43         struct os_time last_bgscan;
  44         char *fname;
  45         struct dl_list bss;
  46         int *supp_freqs;
  47         int probe_idx;
  48 };
  49
  50
  51 static void bss_free(struct bgscan_learn_bss *bss)
  52 {
  53         os_free(bss->neigh);
  54         os_free(bss);
  55 }
  56
  57
  58 static int bssid_in_array(u8 *array, size_t array_len, const u8 *bssid)
  59 {
  60         size_t i;
  61
  62         if (array == NULL || array_len == 0)
  63                 return 0;
  64
  65         for (i = 0; i < array_len; i++) {
  66                 if (os_memcmp(array + i * ETH_ALEN, bssid, ETH_ALEN) == 0)
  67                         return 1;
  68         }
  69
  70         return 0;
  71 }
  72
  73
  74 static void bgscan_learn_add_neighbor(struct bgscan_learn_bss *bss,
  75                                       const u8 *bssid)
  76 {
  77         u8 *n;
  78
  79         if (os_memcmp(bss->bssid, bssid, ETH_ALEN) == 0)
  80                 return;
  81         if (bssid_in_array(bss->neigh, bss->num_neigh, bssid))
  82                 return;
  83
  84         n = os_realloc(bss->neigh, (bss->num_neigh + 1) * ETH_ALEN);
  85         if (n == NULL)
  86                 return;
  87
  88         os_memcpy(n + bss->num_neigh * ETH_ALEN, bssid, ETH_ALEN);
  89         bss->neigh = n;
  90         bss->num_neigh++;
  91 }
  92
  93
  94 static struct bgscan_learn_bss * bgscan_learn_get_bss(
  95         struct bgscan_learn_data *data, const u8 *bssid)
  96 {
  97         struct bgscan_learn_bss *bss;
  98
  99         dl_list_for_each(bss, &data->bss, struct bgscan_learn_bss, list) {
 100                 if (os_memcmp(bss->bssid, bssid, ETH_ALEN) == 0)
 101                         return bss;
 102         }
 103         return NULL;
 104 }
 105
 106
 107 static int bgscan_learn_load(struct bgscan_learn_data *data)
 108 {
 109         FILE *f;
 110         char buf[128];
 111         struct bgscan_learn_bss *bss;
 112
 113         if (data->fname == NULL)
 114                 return 0;
 115
 116         f = fopen(data->fname, "r");
 117         if (f == NULL)
 118                 return 0;
 119
 120         wpa_printf(MSG_DEBUG, "bgscan learn: Loading data from %s",
 121                    data->fname);
 122
 123         if (fgets(buf, sizeof(buf), f) == NULL ||
 124             os_strncmp(buf, "wpa_supplicant-bgscan-learn\n", 28) != 0) {
 125                 wpa_printf(MSG_INFO, "bgscan learn: Invalid data file %s",
 126                            data->fname);
 127                 fclose(f);
 128                 return -1;
 129         }
 130
 131         while (fgets(buf, sizeof(buf), f)) {
 132                 if (os_strncmp(buf, "BSS ", 4) == 0) {
 133                         bss = os_zalloc(sizeof(*bss));
 134                         if (!bss)
 135                                 continue;
 136                         if (hwaddr_aton(buf + 4, bss->bssid) < 0) {
 137                                 bss_free(bss);
 138                                 continue;
 139                         }
 140                         bss->freq = atoi(buf + 4 + 18);
 141                         dl_list_add(&data->bss, &bss->list);
 142                         wpa_printf(MSG_DEBUG, "bgscan learn: Loaded BSS "
 143                                    "entry: " MACSTR " freq=%d",
 144                                    MAC2STR(bss->bssid), bss->freq);
 145                 }
 146
 147                 if (os_strncmp(buf, "NEIGHBOR ", 9) == 0) {
 148                         u8 addr[ETH_ALEN];
 149
 150                         if (hwaddr_aton(buf + 9, addr) < 0)
 151                                 continue;
 152                         bss = bgscan_learn_get_bss(data, addr);
 153                         if (bss == NULL)
 154                                 continue;
 155                         if (hwaddr_aton(buf + 9 + 18, addr) < 0)
 156                                 continue;
 157
 158                         bgscan_learn_add_neighbor(bss, addr);
 159                 }
 160         }
 161
 162         fclose(f);
 163         return 0;
 164 }
 165
 166
 167 static void bgscan_learn_save(struct bgscan_learn_data *data)
 168 {
 169         FILE *f;
 170         struct bgscan_learn_bss *bss;
 171
 172         if (data->fname == NULL)
 173                 return;
 174
 175         wpa_printf(MSG_DEBUG, "bgscan learn: Saving data to %s",
 176                    data->fname);
 177
 178         f = fopen(data->fname, "w");
 179         if (f == NULL)
 180                 return;
 181         fprintf(f, "wpa_supplicant-bgscan-learn\n");
 182
 183         dl_list_for_each(bss, &data->bss, struct bgscan_learn_bss, list) {
 184                 fprintf(f, "BSS " MACSTR " %d\n",
 185                         MAC2STR(bss->bssid), bss->freq);
 186         }
 187
 188         dl_list_for_each(bss, &data->bss, struct bgscan_learn_bss, list) {
 189                 size_t i;
 190                 for (i = 0; i < bss->num_neigh; i++) {
 191                         fprintf(f, "NEIGHBOR " MACSTR " " MACSTR "\n",
 192                                 MAC2STR(bss->bssid),
 193                                 MAC2STR(bss->neigh + i * ETH_ALEN));
 194                 }
 195         }
 196
 197         fclose(f);
 198 }
 199
 200
 201 static int in_array(int *array, int val)
 202 {
 203         int i;
 204
 205         if (array == NULL)
 206                 return 0;
 207
 208         for (i = 0; array[i]; i++) {
 209                 if (array[i] == val)
 210                         return 1;
 211         }
 212
 213         return 0;
 214 }
 215
 216
 217 static int * bgscan_learn_get_freqs(struct bgscan_learn_data *data,
 218                                     size_t *count)
 219 {
 220         struct bgscan_learn_bss *bss;
 221         int *freqs = NULL, *n;
 222
 223         *count = 0;
 224
 225         dl_list_for_each(bss, &data->bss, struct bgscan_learn_bss, list) {
 226                 if (in_array(freqs, bss->freq))
 227                         continue;
 228                 n = os_realloc(freqs, (*count + 2) * sizeof(int));
 229                 if (n == NULL)
 230                         return freqs;
 231                 freqs = n;
 232                 freqs[*count] = bss->freq;
 233                 (*count)++;
 234                 freqs[*count] = 0;
 235         }
 236
 237         return freqs;
 238 }
 239
 240
 241 static int * bgscan_learn_get_probe_freq(struct bgscan_learn_data *data,
 242                                          int *freqs, size_t count)
 243 {
 244         int idx, *n;
 245
 246         if (data->supp_freqs == NULL)
 247                 return freqs;
 248
 249         idx = data->probe_idx + 1;
 250         while (idx != data->probe_idx) {
 251                 if (data->supp_freqs[idx] == 0)
 252                         idx = 0;
 253                 if (!in_array(freqs, data->supp_freqs[idx])) {
 254                         wpa_printf(MSG_DEBUG, "bgscan learn: Probe new freq "
 255                                    "%u", data->supp_freqs[idx]);
 256                         data->probe_idx = idx;
 257                         n = os_realloc(freqs, (count + 2) * sizeof(int));
 258                         if (n == NULL)
 259                                 return freqs;
 260                         freqs = n;
 261                         freqs[count] = data->supp_freqs[idx];
 262                         count++;
 263                         freqs[count] = 0;
 264                         break;
 265                 }
 266
 267                 idx++;
 268         }
 269
 270         return freqs;
 271 }
 272
 273
 274 static void bgscan_learn_timeout(void *eloop_ctx, void *timeout_ctx)
 275 {
 276         struct bgscan_learn_data *data = eloop_ctx;
 277         struct wpa_supplicant *wpa_s = data->wpa_s;
 278         struct wpa_driver_scan_params params;
 279         int *freqs = NULL;
 280         size_t count, i;
 281         char msg[100], *pos;
 282
 283         os_memset(&params, 0, sizeof(params));
 284         params.num_ssids = 1;
 285         params.ssids[0].ssid = data->ssid->ssid;
 286         params.ssids[0].ssid_len = data->ssid->ssid_len;
 287         if (data->ssid->scan_freq)
 288                 params.freqs = data->ssid->scan_freq;
 289         else {
 290                 freqs = bgscan_learn_get_freqs(data, &count);
 291                 wpa_printf(MSG_DEBUG, "bgscan learn: BSSes in this ESS have "
 292                            "been seen on %u channels", (unsigned int) count);
 293                 freqs = bgscan_learn_get_probe_freq(data, freqs, count);
 294
 295                 msg[0] = '\0';
 296                 pos = msg;
 297                 for (i = 0; freqs && freqs[i]; i++) {
 298                         int ret;
 299                         ret = os_snprintf(pos, msg + sizeof(msg) - pos, " %d",
 300                                           freqs[i]);
 301                         if (ret < 0 || ret >= msg + sizeof(msg) - pos)
 302                                 break;
 303                         pos += ret;
 304                 }
 305                 pos[0] = '\0';
 306                 wpa_printf(MSG_DEBUG, "bgscan learn: Scanning frequencies:%s",
 307                            msg);
 308                 params.freqs = freqs;
 309         }
 310
 311         wpa_printf(MSG_DEBUG, "bgscan learn: Request a background scan");
 312         if (wpa_supplicant_trigger_scan(wpa_s, &params)) {
 313                 wpa_printf(MSG_DEBUG, "bgscan learn: Failed to trigger scan");
 314                 eloop_register_timeout(data->scan_interval, 0,
 315                                        bgscan_learn_timeout, data, NULL);
 316         } else
 317                 os_get_time(&data->last_bgscan);
 318         os_free(freqs);
 319 }
 320
 321
 322 static int bgscan_learn_get_params(struct bgscan_learn_data *data,
 323                                    const char *params)
 324 {
 325         const char *pos;
 326
 327         if (params == NULL)
 328                 return 0;
 329
 330         data->short_interval = atoi(params);
 331
 332         pos = os_strchr(params, ':');
 333         if (pos == NULL)
 334                 return 0;
 335         pos++;
 336         data->signal_threshold = atoi(pos);
 337         pos = os_strchr(pos, ':');
 338         if (pos == NULL) {
 339                 wpa_printf(MSG_ERROR, "bgscan learn: Missing scan interval "
 340                            "for high signal");
 341                 return -1;
 342         }
 343         pos++;
 344         data->long_interval = atoi(pos);
 345         pos = os_strchr(pos, ':');
 346         if (pos) {
 347                 pos++;
 348                 data->fname = os_strdup(pos);
 349         }
 350
 351         return 0;
 352 }
 353
 354
 355 static int * bgscan_learn_get_supp_freqs(struct wpa_supplicant *wpa_s)
 356 {
 357         struct hostapd_hw_modes *modes;
 358         u16 num_modes, flags;
 359         int i, j, *freqs = NULL, *n;
 360         size_t count = 0;
 361
 362         modes = wpa_drv_get_hw_feature_data(wpa_s, &num_modes, &flags);
 363         if (!modes)
 364                 return NULL;
 365
 366         for (i = 0; i < num_modes; i++) {
 367                 for (j = 0; j < modes[i].num_channels; j++) {
 368                         if (modes[i].channels[j].flag & HOSTAPD_CHAN_DISABLED)
 369                                 continue;
 370                         n = os_realloc(freqs, (count + 2) * sizeof(int));
 371                         if (!n)
 372                                 continue;
 373
 374                         freqs = n;
 375                         freqs[count] = modes[i].channels[j].freq;
 376                         count++;
 377                         freqs[count] = 0;
 378                 }
 379                 os_free(modes[i].channels);
 380                 os_free(modes[i].rates);
 381         }
 382         os_free(modes);
 383
 384         return freqs;
 385 }
 386
 387
 388 static void * bgscan_learn_init(struct wpa_supplicant *wpa_s,
 389                                 const char *params,
 390                                 const struct wpa_ssid *ssid)
 391 {
 392         struct bgscan_learn_data *data;
 393
 394         data = os_zalloc(sizeof(*data));
 395         if (data == NULL)
 396                 return NULL;
 397         dl_list_init(&data->bss);
 398         data->wpa_s = wpa_s;
 399         data->ssid = ssid;
 400         if (bgscan_learn_get_params(data, params) < 0) {
 401                 os_free(data->fname);
 402                 os_free(data);
 403                 return NULL;
 404         }
 405         if (data->short_interval <= 0)
 406                 data->short_interval = 30;
 407         if (data->long_interval <= 0)
 408                 data->long_interval = 30;
 409
 410         if (bgscan_learn_load(data) < 0) {
 411                 os_free(data->fname);
 412                 os_free(data);
 413                 return NULL;
 414         }
 415
 416         wpa_printf(MSG_DEBUG, "bgscan learn: Signal strength threshold %d  "
 417                    "Short bgscan interval %d  Long bgscan interval %d",
 418                    data->signal_threshold, data->short_interval,
 419                    data->long_interval);
 420
 421         if (data->signal_threshold &&
 422             wpa_drv_signal_monitor(wpa_s, data->signal_threshold, 4) < 0) {
 423                 wpa_printf(MSG_ERROR, "bgscan learn: Failed to enable "
 424                            "signal strength monitoring");
 425         }
 426
 427         data->supp_freqs = bgscan_learn_get_supp_freqs(wpa_s);
 428         data->scan_interval = data->short_interval;
 429         eloop_register_timeout(data->scan_interval, 0, bgscan_learn_timeout,
 430                                data, NULL);
 431
 432         /*
 433          * This function is called immediately after an association, so it is
 434          * reasonable to assume that a scan was completed recently. This makes
 435          * us skip an immediate new scan in cases where the current signal
 436          * level is below the bgscan threshold.
 437          */
 438         os_get_time(&data->last_bgscan);
 439
 440         return data;
 441 }
 442
 443
 444 static void bgscan_learn_deinit(void *priv)
 445 {
 446         struct bgscan_learn_data *data = priv;
 447         struct bgscan_learn_bss *bss, *n;
 448
 449         bgscan_learn_save(data);
 450         eloop_cancel_timeout(bgscan_learn_timeout, data, NULL);
 451         if (data->signal_threshold)
 452                 wpa_drv_signal_monitor(data->wpa_s, 0, 0);
 453         os_free(data->fname);
 454         dl_list_for_each_safe(bss, n, &data->bss, struct bgscan_learn_bss,
 455                               list) {
 456                 dl_list_del(&bss->list);
 457                 bss_free(bss);
 458         }
 459         os_free(data->supp_freqs);
 460         os_free(data);
 461 }
 462
 463
 464 static int bgscan_learn_bss_match(struct bgscan_learn_data *data,
 465                                   struct wpa_scan_res *bss)
 466 {
 467         const u8 *ie;
 468
 469         ie = wpa_scan_get_ie(bss, WLAN_EID_SSID);
 470         if (ie == NULL)
 471                 return 0;
 472
 473         if (data->ssid->ssid_len != ie[1] ||
 474             os_memcmp(data->ssid->ssid, ie + 2, ie[1]) != 0)
 475                 return 0; /* SSID mismatch */
 476
 477         return 1;
 478 }
 479
 480
 481 static int bgscan_learn_notify_scan(void *priv,
 482                                     struct wpa_scan_results *scan_res)
 483 {
 484         struct bgscan_learn_data *data = priv;
 485         size_t i, j;
 486 #define MAX_BSS 50
 487         u8 bssid[MAX_BSS * ETH_ALEN];
 488         size_t num_bssid = 0;
 489
 490         wpa_printf(MSG_DEBUG, "bgscan learn: scan result notification");
 491
 492         eloop_cancel_timeout(bgscan_learn_timeout, data, NULL);
 493         eloop_register_timeout(data->scan_interval, 0, bgscan_learn_timeout,
 494                                data, NULL);
 495
 496         for (i = 0; i < scan_res->num; i++) {
 497                 struct wpa_scan_res *res = scan_res->res[i];
 498                 if (!bgscan_learn_bss_match(data, res))
 499                         continue;
 500
 501                 if (num_bssid < MAX_BSS) {
 502                         os_memcpy(bssid + num_bssid * ETH_ALEN, res->bssid,
 503                                   ETH_ALEN);
 504                         num_bssid++;
 505                 }
 506         }
 507         wpa_printf(MSG_DEBUG, "bgscan learn: %u matching BSSes in scan "
 508                    "results", (unsigned int) num_bssid);
 509
 510         for (i = 0; i < scan_res->num; i++) {
 511                 struct wpa_scan_res *res = scan_res->res[i];
 512                 struct bgscan_learn_bss *bss;
 513
 514                 if (!bgscan_learn_bss_match(data, res))
 515                         continue;
 516
 517                 bss = bgscan_learn_get_bss(data, res->bssid);
 518                 if (bss && bss->freq != res->freq) {
 519                         wpa_printf(MSG_DEBUG, "bgscan learn: Update BSS "
 520                            MACSTR " freq %d -> %d",
 521                                    MAC2STR(res->bssid), bss->freq, res->freq);
 522                         bss->freq = res->freq;
 523                 } else if (!bss) {
 524                         wpa_printf(MSG_DEBUG, "bgscan learn: Add BSS " MACSTR
 525                                    " freq=%d", MAC2STR(res->bssid), res->freq);
 526                         bss = os_zalloc(sizeof(*bss));
 527                         if (!bss)
 528                                 continue;
 529                         os_memcpy(bss->bssid, res->bssid, ETH_ALEN);
 530                         bss->freq = res->freq;
 531                         dl_list_add(&data->bss, &bss->list);
 532                 }
 533
 534                 for (j = 0; j < num_bssid; j++) {
 535                         u8 *addr = bssid + j * ETH_ALEN;
 536                         bgscan_learn_add_neighbor(bss, addr);
 537                 }
 538         }
 539
 540         /*
 541          * A more advanced bgscan could process scan results internally, select
 542          * the BSS and request roam if needed. This sample uses the existing
 543          * BSS/ESS selection routine. Change this to return 1 if selection is
 544          * done inside the bgscan module.
 545          */
 546
 547         return 0;
 548 }
 549
 550
 551 static void bgscan_learn_notify_beacon_loss(void *priv)
 552 {
 553         wpa_printf(MSG_DEBUG, "bgscan learn: beacon loss");
 554         /* TODO: speed up background scanning */
 555 }
 556
 557
 558 static void bgscan_learn_notify_signal_change(void *priv, int above,
 559                                               int current_signal,
 560                                               int current_noise,
 561                                               int current_txrate)
 562 {
 563         struct bgscan_learn_data *data = priv;
 564         int scan = 0;
 565         struct os_time now;
 566
 567         if (data->short_interval == data->long_interval ||
 568             data->signal_threshold == 0)
 569                 return;
 570
 571         wpa_printf(MSG_DEBUG, "bgscan learn: signal level changed "
 572                    "(above=%d current_signal=%d current_noise=%d "
 573                    "current_txrate=%d)", above, current_signal,
 574                    current_noise, current_txrate);
 575         if (data->scan_interval == data->long_interval && !above) {
 576                 wpa_printf(MSG_DEBUG, "bgscan learn: Start using short bgscan "
 577                            "interval");
 578                 data->scan_interval = data->short_interval;
 579                 os_get_time(&now);
 580                 if (now.sec > data->last_bgscan.sec + 1)
 581                         scan = 1;
 582         } else if (data->scan_interval == data->short_interval && above) {
 583                 wpa_printf(MSG_DEBUG, "bgscan learn: Start using long bgscan "
 584                            "interval");
 585                 data->scan_interval = data->long_interval;
 586                 eloop_cancel_timeout(bgscan_learn_timeout, data, NULL);
 587                 eloop_register_timeout(data->scan_interval, 0,
 588                                        bgscan_learn_timeout, data, NULL);
 589         } else if (!above) {
 590                 /*
 591                  * Signal dropped further 4 dB. Request a new scan if we have
 592                  * not yet scanned in a while.
 593                  */
 594                 os_get_time(&now);
 595                 if (now.sec > data->last_bgscan.sec + 10)
 596                         scan = 1;
 597         }
 598
 599         if (scan) {
 600                 wpa_printf(MSG_DEBUG, "bgscan learn: Trigger immediate scan");
 601                 eloop_cancel_timeout(bgscan_learn_timeout, data, NULL);
 602                 eloop_register_timeout(0, 0, bgscan_learn_timeout, data, NULL);
 603         }
 604 }
 605
 606
 607 const struct bgscan_ops bgscan_learn_ops = {
 608         .name = "learn",
 609         .init = bgscan_learn_init,
 610         .deinit = bgscan_learn_deinit,
 611         .notify_scan = bgscan_learn_notify_scan,
 612         .notify_beacon_loss = bgscan_learn_notify_beacon_loss,
 613         .notify_signal_change = bgscan_learn_notify_signal_change,
 614 };