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