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(¶ms, 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, ¶ms)) { 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 int i, j, *freqs = NULL, *n; 359 size_t count = 0; 360 361 modes = wpa_s->hw.modes; 362 if (modes == NULL) 363 return NULL; 364 365 for (i = 0; i < wpa_s->hw.num_modes; i++) { 366 for (j = 0; j < modes[i].num_channels; j++) { 367 if (modes[i].channels[j].flag & HOSTAPD_CHAN_DISABLED) 368 continue; 369 n = os_realloc(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 }; 611