1 /* 2 * WPA Supplicant - background scan and roaming module: learn 3 * Copyright (c) 2009-2010, Jouni Malinen <j (at) 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 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 }; 615
