bgscan_learn.c revision 281806
1198090Srdivacky/* 2198090Srdivacky * WPA Supplicant - background scan and roaming module: learn 3198090Srdivacky * Copyright (c) 2009-2010, Jouni Malinen <j@w1.fi> 4198090Srdivacky * 5198090Srdivacky * This software may be distributed under the terms of the BSD license. 6198090Srdivacky * See README for more details. 7198090Srdivacky */ 8198090Srdivacky 9198090Srdivacky#include "includes.h" 10198090Srdivacky 11198090Srdivacky#include "common.h" 12198090Srdivacky#include "eloop.h" 13198090Srdivacky#include "list.h" 14198090Srdivacky#include "common/ieee802_11_defs.h" 15198090Srdivacky#include "drivers/driver.h" 16198090Srdivacky#include "config_ssid.h" 17234353Sdim#include "wpa_supplicant_i.h" 18249423Sdim#include "driver_i.h" 19234353Sdim#include "scan.h" 20198090Srdivacky#include "bgscan.h" 21198090Srdivacky 22234353Sdimstruct bgscan_learn_bss { 23234353Sdim struct dl_list list; 24208599Srdivacky u8 bssid[ETH_ALEN]; 25208599Srdivacky int freq; 26234353Sdim u8 *neigh; /* num_neigh * ETH_ALEN buffer */ 27234353Sdim size_t num_neigh; 28234353Sdim}; 29234353Sdim 30198396Srdivackystruct bgscan_learn_data { 31263508Sdim struct wpa_supplicant *wpa_s; 32263508Sdim const struct wpa_ssid *ssid; 33263508Sdim int scan_interval; 34263508Sdim int signal_threshold; 35198090Srdivacky int short_interval; /* use if signal < threshold */ 36198090Srdivacky int long_interval; /* use if signal > threshold */ 37198090Srdivacky struct os_reltime last_bgscan; 38208599Srdivacky char *fname; 39207618Srdivacky struct dl_list bss; 40207618Srdivacky int *supp_freqs; 41263508Sdim int probe_idx; 42263508Sdim}; 43207618Srdivacky 44198090Srdivacky 45198396Srdivackystatic void bss_free(struct bgscan_learn_bss *bss) 46212904Sdim{ 47226633Sdim os_free(bss->neigh); 48198396Srdivacky os_free(bss); 49263508Sdim} 50212904Sdim 51212904Sdim 52263508Sdimstatic int bssid_in_array(u8 *array, size_t array_len, const u8 *bssid) 53263508Sdim{ 54198090Srdivacky size_t i; 55208599Srdivacky 56198090Srdivacky if (array == NULL || array_len == 0) 57263508Sdim return 0; 58198090Srdivacky 59198892Srdivacky for (i = 0; i < array_len; i++) { 60198090Srdivacky if (os_memcmp(array + i * ETH_ALEN, bssid, ETH_ALEN) == 0) 61198396Srdivacky return 1; 62263508Sdim } 63263508Sdim 64263508Sdim return 0; 65263508Sdim} 66226633Sdim 67198396Srdivacky 68263508Sdimstatic void bgscan_learn_add_neighbor(struct bgscan_learn_bss *bss, 69263508Sdim const u8 *bssid) 70198090Srdivacky{ 71198090Srdivacky u8 *n; 72263508Sdim 73263508Sdim if (os_memcmp(bss->bssid, bssid, ETH_ALEN) == 0) 74198090Srdivacky return; 75198396Srdivacky if (bssid_in_array(bss->neigh, bss->num_neigh, bssid)) 76263508Sdim return; 77263508Sdim 78198090Srdivacky n = os_realloc_array(bss->neigh, bss->num_neigh + 1, ETH_ALEN); 79198396Srdivacky if (n == NULL) 80263508Sdim return; 81263508Sdim 82198090Srdivacky os_memcpy(n + bss->num_neigh * ETH_ALEN, bssid, ETH_ALEN); 83263508Sdim bss->neigh = n; 84263508Sdim bss->num_neigh++; 85263508Sdim} 86198090Srdivacky 87263508Sdim 88198090Srdivackystatic struct bgscan_learn_bss * bgscan_learn_get_bss( 89198090Srdivacky struct bgscan_learn_data *data, const u8 *bssid) 90198090Srdivacky{ 91198090Srdivacky struct bgscan_learn_bss *bss; 92198090Srdivacky 93263508Sdim dl_list_for_each(bss, &data->bss, struct bgscan_learn_bss, list) { 94198090Srdivacky if (os_memcmp(bss->bssid, bssid, ETH_ALEN) == 0) 95198090Srdivacky return bss; 96198090Srdivacky } 97198090Srdivacky return NULL; 98198090Srdivacky} 99198090Srdivacky 100198090Srdivacky 101198396Srdivackystatic int bgscan_learn_load(struct bgscan_learn_data *data) 102263508Sdim{ 103263508Sdim FILE *f; 104263508Sdim char buf[128]; 105263508Sdim struct bgscan_learn_bss *bss; 106263508Sdim 107263508Sdim if (data->fname == NULL) 108263508Sdim return 0; 109198090Srdivacky 110198396Srdivacky f = fopen(data->fname, "r"); 111263508Sdim if (f == NULL) 112263508Sdim return 0; 113263508Sdim 114263508Sdim wpa_printf(MSG_DEBUG, "bgscan learn: Loading data from %s", 115212904Sdim data->fname); 116212904Sdim 117212904Sdim if (fgets(buf, sizeof(buf), f) == NULL || 118198090Srdivacky os_strncmp(buf, "wpa_supplicant-bgscan-learn\n", 28) != 0) { 119198090Srdivacky wpa_printf(MSG_INFO, "bgscan learn: Invalid data file %s", 120207618Srdivacky data->fname); 121243830Sdim fclose(f); 122243830Sdim return -1; 123198090Srdivacky } 124263508Sdim 125263508Sdim while (fgets(buf, sizeof(buf), f)) { 126263508Sdim if (os_strncmp(buf, "BSS ", 4) == 0) { 127263508Sdim bss = os_zalloc(sizeof(*bss)); 128218893Sdim if (!bss) 129218893Sdim continue; 130218893Sdim if (hwaddr_aton(buf + 4, bss->bssid) < 0) { 131218893Sdim bss_free(bss); 132218893Sdim continue; 133218893Sdim } 134218893Sdim bss->freq = atoi(buf + 4 + 18); 135218893Sdim dl_list_add(&data->bss, &bss->list); 136218893Sdim wpa_printf(MSG_DEBUG, "bgscan learn: Loaded BSS " 137218893Sdim "entry: " MACSTR " freq=%d", 138224145Sdim MAC2STR(bss->bssid), bss->freq); 139218893Sdim } 140218893Sdim 141263508Sdim if (os_strncmp(buf, "NEIGHBOR ", 9) == 0) { 142263508Sdim u8 addr[ETH_ALEN]; 143263508Sdim 144263508Sdim if (hwaddr_aton(buf + 9, addr) < 0) 145263508Sdim continue; 146218893Sdim bss = bgscan_learn_get_bss(data, addr); 147218893Sdim if (bss == NULL) 148218893Sdim continue; 149263508Sdim if (hwaddr_aton(buf + 9 + 18, addr) < 0) 150263508Sdim continue; 151263508Sdim 152263508Sdim bgscan_learn_add_neighbor(bss, addr); 153218893Sdim } 154234353Sdim } 155218893Sdim 156263508Sdim fclose(f); 157263508Sdim return 0; 158218893Sdim} 159218893Sdim 160218893Sdim 161263508Sdimstatic void bgscan_learn_save(struct bgscan_learn_data *data) 162263508Sdim{ 163218893Sdim FILE *f; 164218893Sdim struct bgscan_learn_bss *bss; 165198090Srdivacky 166263508Sdim if (data->fname == NULL) 167218893Sdim return; 168218893Sdim 169218893Sdim wpa_printf(MSG_DEBUG, "bgscan learn: Saving data to %s", 170263508Sdim data->fname); 171224145Sdim 172224145Sdim f = fopen(data->fname, "w"); 173218893Sdim if (f == NULL) 174218893Sdim return; 175198090Srdivacky fprintf(f, "wpa_supplicant-bgscan-learn\n"); 176198090Srdivacky 177198090Srdivacky 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 195static 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 211static 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 235static 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; 244 do { 245 if (!in_array(freqs, data->supp_freqs[idx])) { 246 wpa_printf(MSG_DEBUG, "bgscan learn: Probe new freq " 247 "%u", data->supp_freqs[idx]); 248 data->probe_idx = idx + 1; 249 if (data->supp_freqs[data->probe_idx] == 0) 250 data->probe_idx = 0; 251 n = os_realloc_array(freqs, count + 2, sizeof(int)); 252 if (n == NULL) 253 return freqs; 254 freqs = n; 255 freqs[count] = data->supp_freqs[idx]; 256 count++; 257 freqs[count] = 0; 258 break; 259 } 260 261 idx++; 262 if (data->supp_freqs[idx] == 0) 263 idx = 0; 264 } while (idx != data->probe_idx); 265 266 return freqs; 267} 268 269 270static void bgscan_learn_timeout(void *eloop_ctx, void *timeout_ctx) 271{ 272 struct bgscan_learn_data *data = eloop_ctx; 273 struct wpa_supplicant *wpa_s = data->wpa_s; 274 struct wpa_driver_scan_params params; 275 int *freqs = NULL; 276 size_t count, i; 277 char msg[100], *pos; 278 279 os_memset(¶ms, 0, sizeof(params)); 280 params.num_ssids = 1; 281 params.ssids[0].ssid = data->ssid->ssid; 282 params.ssids[0].ssid_len = data->ssid->ssid_len; 283 if (data->ssid->scan_freq) 284 params.freqs = data->ssid->scan_freq; 285 else { 286 freqs = bgscan_learn_get_freqs(data, &count); 287 wpa_printf(MSG_DEBUG, "bgscan learn: BSSes in this ESS have " 288 "been seen on %u channels", (unsigned int) count); 289 freqs = bgscan_learn_get_probe_freq(data, freqs, count); 290 291 msg[0] = '\0'; 292 pos = msg; 293 for (i = 0; freqs && freqs[i]; i++) { 294 int ret; 295 ret = os_snprintf(pos, msg + sizeof(msg) - pos, " %d", 296 freqs[i]); 297 if (os_snprintf_error(msg + sizeof(msg) - pos, ret)) 298 break; 299 pos += ret; 300 } 301 pos[0] = '\0'; 302 wpa_printf(MSG_DEBUG, "bgscan learn: Scanning frequencies:%s", 303 msg); 304 params.freqs = freqs; 305 } 306 307 wpa_printf(MSG_DEBUG, "bgscan learn: Request a background scan"); 308 if (wpa_supplicant_trigger_scan(wpa_s, ¶ms)) { 309 wpa_printf(MSG_DEBUG, "bgscan learn: Failed to trigger scan"); 310 eloop_register_timeout(data->scan_interval, 0, 311 bgscan_learn_timeout, data, NULL); 312 } else 313 os_get_reltime(&data->last_bgscan); 314 os_free(freqs); 315} 316 317 318static int bgscan_learn_get_params(struct bgscan_learn_data *data, 319 const char *params) 320{ 321 const char *pos; 322 323 if (params == NULL) 324 return 0; 325 326 data->short_interval = atoi(params); 327 328 pos = os_strchr(params, ':'); 329 if (pos == NULL) 330 return 0; 331 pos++; 332 data->signal_threshold = atoi(pos); 333 pos = os_strchr(pos, ':'); 334 if (pos == NULL) { 335 wpa_printf(MSG_ERROR, "bgscan learn: Missing scan interval " 336 "for high signal"); 337 return -1; 338 } 339 pos++; 340 data->long_interval = atoi(pos); 341 pos = os_strchr(pos, ':'); 342 if (pos) { 343 pos++; 344 data->fname = os_strdup(pos); 345 } 346 347 return 0; 348} 349 350 351static int * bgscan_learn_get_supp_freqs(struct wpa_supplicant *wpa_s) 352{ 353 struct hostapd_hw_modes *modes; 354 int i, j, *freqs = NULL, *n; 355 size_t count = 0; 356 357 modes = wpa_s->hw.modes; 358 if (modes == NULL) 359 return NULL; 360 361 for (i = 0; i < wpa_s->hw.num_modes; i++) { 362 for (j = 0; j < modes[i].num_channels; j++) { 363 if (modes[i].channels[j].flag & HOSTAPD_CHAN_DISABLED) 364 continue; 365 /* some hw modes (e.g. 11b & 11g) contain same freqs */ 366 if (in_array(freqs, modes[i].channels[j].freq)) 367 continue; 368 n = os_realloc_array(freqs, count + 2, sizeof(int)); 369 if (n == NULL) 370 continue; 371 372 freqs = n; 373 freqs[count] = modes[i].channels[j].freq; 374 count++; 375 freqs[count] = 0; 376 } 377 } 378 379 return freqs; 380} 381 382 383static void * bgscan_learn_init(struct wpa_supplicant *wpa_s, 384 const char *params, 385 const struct wpa_ssid *ssid) 386{ 387 struct bgscan_learn_data *data; 388 389 data = os_zalloc(sizeof(*data)); 390 if (data == NULL) 391 return NULL; 392 dl_list_init(&data->bss); 393 data->wpa_s = wpa_s; 394 data->ssid = ssid; 395 if (bgscan_learn_get_params(data, params) < 0) { 396 os_free(data->fname); 397 os_free(data); 398 return NULL; 399 } 400 if (data->short_interval <= 0) 401 data->short_interval = 30; 402 if (data->long_interval <= 0) 403 data->long_interval = 30; 404 405 if (bgscan_learn_load(data) < 0) { 406 os_free(data->fname); 407 os_free(data); 408 return NULL; 409 } 410 411 wpa_printf(MSG_DEBUG, "bgscan learn: Signal strength threshold %d " 412 "Short bgscan interval %d Long bgscan interval %d", 413 data->signal_threshold, data->short_interval, 414 data->long_interval); 415 416 if (data->signal_threshold && 417 wpa_drv_signal_monitor(wpa_s, data->signal_threshold, 4) < 0) { 418 wpa_printf(MSG_ERROR, "bgscan learn: Failed to enable " 419 "signal strength monitoring"); 420 } 421 422 data->supp_freqs = bgscan_learn_get_supp_freqs(wpa_s); 423 data->scan_interval = data->short_interval; 424 if (data->signal_threshold) { 425 /* Poll for signal info to set initial scan interval */ 426 struct wpa_signal_info siginfo; 427 if (wpa_drv_signal_poll(wpa_s, &siginfo) == 0 && 428 siginfo.current_signal >= data->signal_threshold) 429 data->scan_interval = data->long_interval; 430 } 431 432 eloop_register_timeout(data->scan_interval, 0, bgscan_learn_timeout, 433 data, NULL); 434 435 /* 436 * This function is called immediately after an association, so it is 437 * reasonable to assume that a scan was completed recently. This makes 438 * us skip an immediate new scan in cases where the current signal 439 * level is below the bgscan threshold. 440 */ 441 os_get_reltime(&data->last_bgscan); 442 443 return data; 444} 445 446 447static void bgscan_learn_deinit(void *priv) 448{ 449 struct bgscan_learn_data *data = priv; 450 struct bgscan_learn_bss *bss, *n; 451 452 bgscan_learn_save(data); 453 eloop_cancel_timeout(bgscan_learn_timeout, data, NULL); 454 if (data->signal_threshold) 455 wpa_drv_signal_monitor(data->wpa_s, 0, 0); 456 os_free(data->fname); 457 dl_list_for_each_safe(bss, n, &data->bss, struct bgscan_learn_bss, 458 list) { 459 dl_list_del(&bss->list); 460 bss_free(bss); 461 } 462 os_free(data->supp_freqs); 463 os_free(data); 464} 465 466 467static int bgscan_learn_bss_match(struct bgscan_learn_data *data, 468 struct wpa_scan_res *bss) 469{ 470 const u8 *ie; 471 472 ie = wpa_scan_get_ie(bss, WLAN_EID_SSID); 473 if (ie == NULL) 474 return 0; 475 476 if (data->ssid->ssid_len != ie[1] || 477 os_memcmp(data->ssid->ssid, ie + 2, ie[1]) != 0) 478 return 0; /* SSID mismatch */ 479 480 return 1; 481} 482 483 484static int bgscan_learn_notify_scan(void *priv, 485 struct wpa_scan_results *scan_res) 486{ 487 struct bgscan_learn_data *data = priv; 488 size_t i, j; 489#define MAX_BSS 50 490 u8 bssid[MAX_BSS * ETH_ALEN]; 491 size_t num_bssid = 0; 492 493 wpa_printf(MSG_DEBUG, "bgscan learn: scan result notification"); 494 495 eloop_cancel_timeout(bgscan_learn_timeout, data, NULL); 496 eloop_register_timeout(data->scan_interval, 0, bgscan_learn_timeout, 497 data, NULL); 498 499 for (i = 0; i < scan_res->num; i++) { 500 struct wpa_scan_res *res = scan_res->res[i]; 501 if (!bgscan_learn_bss_match(data, res)) 502 continue; 503 504 if (num_bssid < MAX_BSS) { 505 os_memcpy(bssid + num_bssid * ETH_ALEN, res->bssid, 506 ETH_ALEN); 507 num_bssid++; 508 } 509 } 510 wpa_printf(MSG_DEBUG, "bgscan learn: %u matching BSSes in scan " 511 "results", (unsigned int) num_bssid); 512 513 for (i = 0; i < scan_res->num; i++) { 514 struct wpa_scan_res *res = scan_res->res[i]; 515 struct bgscan_learn_bss *bss; 516 517 if (!bgscan_learn_bss_match(data, res)) 518 continue; 519 520 bss = bgscan_learn_get_bss(data, res->bssid); 521 if (bss && bss->freq != res->freq) { 522 wpa_printf(MSG_DEBUG, "bgscan learn: Update BSS " 523 MACSTR " freq %d -> %d", 524 MAC2STR(res->bssid), bss->freq, res->freq); 525 bss->freq = res->freq; 526 } else if (!bss) { 527 wpa_printf(MSG_DEBUG, "bgscan learn: Add BSS " MACSTR 528 " freq=%d", MAC2STR(res->bssid), res->freq); 529 bss = os_zalloc(sizeof(*bss)); 530 if (!bss) 531 continue; 532 os_memcpy(bss->bssid, res->bssid, ETH_ALEN); 533 bss->freq = res->freq; 534 dl_list_add(&data->bss, &bss->list); 535 } 536 537 for (j = 0; j < num_bssid; j++) { 538 u8 *addr = bssid + j * ETH_ALEN; 539 bgscan_learn_add_neighbor(bss, addr); 540 } 541 } 542 543 /* 544 * A more advanced bgscan could process scan results internally, select 545 * the BSS and request roam if needed. This sample uses the existing 546 * BSS/ESS selection routine. Change this to return 1 if selection is 547 * done inside the bgscan module. 548 */ 549 550 return 0; 551} 552 553 554static void bgscan_learn_notify_beacon_loss(void *priv) 555{ 556 wpa_printf(MSG_DEBUG, "bgscan learn: beacon loss"); 557 /* TODO: speed up background scanning */ 558} 559 560 561static void bgscan_learn_notify_signal_change(void *priv, int above, 562 int current_signal, 563 int current_noise, 564 int current_txrate) 565{ 566 struct bgscan_learn_data *data = priv; 567 int scan = 0; 568 struct os_reltime now; 569 570 if (data->short_interval == data->long_interval || 571 data->signal_threshold == 0) 572 return; 573 574 wpa_printf(MSG_DEBUG, "bgscan learn: signal level changed " 575 "(above=%d current_signal=%d current_noise=%d " 576 "current_txrate=%d)", above, current_signal, 577 current_noise, current_txrate); 578 if (data->scan_interval == data->long_interval && !above) { 579 wpa_printf(MSG_DEBUG, "bgscan learn: Start using short bgscan " 580 "interval"); 581 data->scan_interval = data->short_interval; 582 os_get_reltime(&now); 583 if (now.sec > data->last_bgscan.sec + 1) 584 scan = 1; 585 } else if (data->scan_interval == data->short_interval && above) { 586 wpa_printf(MSG_DEBUG, "bgscan learn: Start using long bgscan " 587 "interval"); 588 data->scan_interval = data->long_interval; 589 eloop_cancel_timeout(bgscan_learn_timeout, data, NULL); 590 eloop_register_timeout(data->scan_interval, 0, 591 bgscan_learn_timeout, data, NULL); 592 } else if (!above) { 593 /* 594 * Signal dropped further 4 dB. Request a new scan if we have 595 * not yet scanned in a while. 596 */ 597 os_get_reltime(&now); 598 if (now.sec > data->last_bgscan.sec + 10) 599 scan = 1; 600 } 601 602 if (scan) { 603 wpa_printf(MSG_DEBUG, "bgscan learn: Trigger immediate scan"); 604 eloop_cancel_timeout(bgscan_learn_timeout, data, NULL); 605 eloop_register_timeout(0, 0, bgscan_learn_timeout, data, NULL); 606 } 607} 608 609 610const struct bgscan_ops bgscan_learn_ops = { 611 .name = "learn", 612 .init = bgscan_learn_init, 613 .deinit = bgscan_learn_deinit, 614 .notify_scan = bgscan_learn_notify_scan, 615 .notify_beacon_loss = bgscan_learn_notify_beacon_loss, 616 .notify_signal_change = bgscan_learn_notify_signal_change, 617}; 618