1 /* 2 * WPA Supplicant - background scan and roaming module: learn 3 * Copyright (c) 2009-2010, Jouni Malinen <j@w1.fi> 4 * 5 * This software may be distributed under the terms of the BSD license. 6 * See README for more details. 7 */ 8 9 #include "includes.h" 10 11 #include "common.h" 12 #include "eloop.h" 13 #include "list.h" 14 #include "common/ieee802_11_defs.h" 15 #include "drivers/driver.h" 16 #include "config_ssid.h" 17 #include "wpa_supplicant_i.h" 18 #include "driver_i.h" 19 #include "scan.h" 20 #include "bgscan.h" 21 22 struct bgscan_learn_bss { 23 struct dl_list list; 24 u8 bssid[ETH_ALEN]; 25 int freq; 26 u8 *neigh; /* num_neigh * ETH_ALEN buffer */ 27 size_t num_neigh; 28 }; 29 30 struct bgscan_learn_data { 31 struct wpa_supplicant *wpa_s; 32 const struct wpa_ssid *ssid; 33 int scan_interval; 34 int signal_threshold; 35 int short_interval; /* use if signal < threshold */ 36 int long_interval; /* use if signal > threshold */ 37 struct os_time last_bgscan; 38 char *fname; 39 struct dl_list bss; 40 int *supp_freqs; 41 int probe_idx; 42 }; 43 44 45 static void bss_free(struct bgscan_learn_bss *bss) 46 { 47 os_free(bss->neigh); 48 os_free(bss); 49 } 50 51 52 static int bssid_in_array(u8 *array, size_t array_len, const u8 *bssid) 53 { 54 size_t i; 55 56 if (array == NULL || array_len == 0) 57 return 0; 58 59 for (i = 0; i < array_len; i++) { 60 if (os_memcmp(array + i * ETH_ALEN, bssid, ETH_ALEN) == 0) 61 return 1; 62 } 63 64 return 0; 65 } 66 67 68 static void bgscan_learn_add_neighbor(struct bgscan_learn_bss *bss, 69 const u8 *bssid) 70 { 71 u8 *n; 72 73 if (os_memcmp(bss->bssid, bssid, ETH_ALEN) == 0) 74 return; 75 if (bssid_in_array(bss->neigh, bss->num_neigh, bssid)) 76 return; 77 78 n = os_realloc_array(bss->neigh, bss->num_neigh + 1, ETH_ALEN); 79 if (n == NULL) 80 return; 81 82 os_memcpy(n + bss->num_neigh * ETH_ALEN, bssid, ETH_ALEN); 83 bss->neigh = n; 84 bss->num_neigh++; 85 } 86 87 88 static struct bgscan_learn_bss * bgscan_learn_get_bss( 89 struct bgscan_learn_data *data, const u8 *bssid) 90 { 91 struct bgscan_learn_bss *bss; 92 93 dl_list_for_each(bss, &data->bss, struct bgscan_learn_bss, list) { 94 if (os_memcmp(bss->bssid, bssid, ETH_ALEN) == 0) 95 return bss; 96 } 97 return NULL; 98 } 99 100 101 static int bgscan_learn_load(struct bgscan_learn_data *data) 102 { 103 FILE *f; 104 char buf[128]; 105 struct bgscan_learn_bss *bss; 106 107 if (data->fname == NULL) 108 return 0; 109 110 f = fopen(data->fname, "r"); 111 if (f == NULL) 112 return 0; 113 114 wpa_printf(MSG_DEBUG, "bgscan learn: Loading data from %s", 115 data->fname); 116 117 if (fgets(buf, sizeof(buf), f) == NULL || 118 os_strncmp(buf, "wpa_supplicant-bgscan-learn\n", 28) != 0) { 119 wpa_printf(MSG_INFO, "bgscan learn: Invalid data file %s", 120 data->fname); 121 fclose(f); 122 return -1; 123 } 124 125 while (fgets(buf, sizeof(buf), f)) { 126 if (os_strncmp(buf, "BSS ", 4) == 0) { 127 bss = os_zalloc(sizeof(*bss)); 128 if (!bss) 129 continue; 130 if (hwaddr_aton(buf + 4, bss->bssid) < 0) { 131 bss_free(bss); 132 continue; 133 } 134 bss->freq = atoi(buf + 4 + 18); 135 dl_list_add(&data->bss, &bss->list); 136 wpa_printf(MSG_DEBUG, "bgscan learn: Loaded BSS " 137 "entry: " MACSTR " freq=%d", 138 MAC2STR(bss->bssid), bss->freq); 139 } 140 141 if (os_strncmp(buf, "NEIGHBOR ", 9) == 0) { 142 u8 addr[ETH_ALEN]; 143 144 if (hwaddr_aton(buf + 9, addr) < 0) 145 continue; 146 bss = bgscan_learn_get_bss(data, addr); 147 if (bss == NULL) 148 continue; 149 if (hwaddr_aton(buf + 9 + 18, addr) < 0) 150 continue; 151 152 bgscan_learn_add_neighbor(bss, addr); 153 } 154 } 155 156 fclose(f); 157 return 0; 158 } 159 160 161 static void bgscan_learn_save(struct bgscan_learn_data *data) 162 { 163 FILE *f; 164 struct bgscan_learn_bss *bss; 165 166 if (data->fname == NULL) 167 return; 168 169 wpa_printf(MSG_DEBUG, "bgscan learn: Saving data to %s", 170 data->fname); 171 172 f = fopen(data->fname, "w"); 173 if (f == NULL) 174 return; 175 fprintf(f, "wpa_supplicant-bgscan-learn\n"); 176 177 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 } 193 194 195 static 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 } 209 210 211 static 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 } 233 234 235 static 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 + 1; 244 while (idx != data->probe_idx) { 245 if (data->supp_freqs[idx] == 0) { 246 if (data->probe_idx == 0) 247 break; 248 idx = 0; 249 } 250 if (!in_array(freqs, data->supp_freqs[idx])) { 251 wpa_printf(MSG_DEBUG, "bgscan learn: Probe new freq " 252 "%u", data->supp_freqs[idx]); 253 data->probe_idx = idx; 254 n = os_realloc_array(freqs, count + 2, sizeof(int)); 255 if (n == NULL) 256 return freqs; 257 freqs = n; 258 freqs[count] = data->supp_freqs[idx]; 259 count++; 260 freqs[count] = 0; 261 break; 262 } 263 264 idx++; 265 } 266 267 return freqs; 268 } 269 270 271 static void bgscan_learn_timeout(void *eloop_ctx, void *timeout_ctx) 272 { 273 struct bgscan_learn_data *data = eloop_ctx; 274 struct wpa_supplicant *wpa_s = data->wpa_s; 275 struct wpa_driver_scan_params params; 276 int *freqs = NULL; 277 size_t count, i; 278 char msg[100], *pos; 279 280 os_memset(¶ms, 0, sizeof(params)); 281 params.num_ssids = 1; 282 params.ssids[0].ssid = data->ssid->ssid; 283 params.ssids[0].ssid_len = data->ssid->ssid_len; 284 if (data->ssid->scan_freq) 285 params.freqs = data->ssid->scan_freq; 286 else { 287 freqs = bgscan_learn_get_freqs(data, &count); 288 wpa_printf(MSG_DEBUG, "bgscan learn: BSSes in this ESS have " 289 "been seen on %u channels", (unsigned int) count); 290 freqs = bgscan_learn_get_probe_freq(data, freqs, count); 291 292 msg[0] = '\0'; 293 pos = msg; 294 for (i = 0; freqs && freqs[i]; i++) { 295 int ret; 296 ret = os_snprintf(pos, msg + sizeof(msg) - pos, " %d", 297 freqs[i]); 298 if (ret < 0 || ret >= msg + sizeof(msg) - pos) 299 break; 300 pos += ret; 301 } 302 pos[0] = '\0'; 303 wpa_printf(MSG_DEBUG, "bgscan learn: Scanning frequencies:%s", 304 msg); 305 params.freqs = freqs; 306 } 307 308 wpa_printf(MSG_DEBUG, "bgscan learn: Request a background scan"); 309 if (wpa_supplicant_trigger_scan(wpa_s, ¶ms)) { 310 wpa_printf(MSG_DEBUG, "bgscan learn: Failed to trigger scan"); 311 eloop_register_timeout(data->scan_interval, 0, 312 bgscan_learn_timeout, data, NULL); 313 } else 314 os_get_time(&data->last_bgscan); 315 os_free(freqs); 316 } 317 318 319 static int bgscan_learn_get_params(struct bgscan_learn_data *data, 320 const char *params) 321 { 322 const char *pos; 323 324 if (params == NULL) 325 return 0; 326 327 data->short_interval = atoi(params); 328 329 pos = os_strchr(params, ':'); 330 if (pos == NULL) 331 return 0; 332 pos++; 333 data->signal_threshold = atoi(pos); 334 pos = os_strchr(pos, ':'); 335 if (pos == NULL) { 336 wpa_printf(MSG_ERROR, "bgscan learn: Missing scan interval " 337 "for high signal"); 338 return -1; 339 } 340 pos++; 341 data->long_interval = atoi(pos); 342 pos = os_strchr(pos, ':'); 343 if (pos) { 344 pos++; 345 data->fname = os_strdup(pos); 346 } 347 348 return 0; 349 } 350 351 352 static int * bgscan_learn_get_supp_freqs(struct wpa_supplicant *wpa_s) 353 { 354 struct hostapd_hw_modes *modes; 355 int i, j, *freqs = NULL, *n; 356 size_t count = 0; 357 358 modes = wpa_s->hw.modes; 359 if (modes == NULL) 360 return NULL; 361 362 for (i = 0; i < wpa_s->hw.num_modes; i++) { 363 for (j = 0; j < modes[i].num_channels; j++) { 364 if (modes[i].channels[j].flag & HOSTAPD_CHAN_DISABLED) 365 continue; 366 n = os_realloc_array(freqs, count + 2, sizeof(int)); 367 if (n == NULL) 368 continue; 369 370 freqs = n; 371 freqs[count] = modes[i].channels[j].freq; 372 count++; 373 freqs[count] = 0; 374 } 375 } 376 377 return freqs; 378 } 379 380 381 static void * bgscan_learn_init(struct wpa_supplicant *wpa_s, 382 const char *params, 383 const struct wpa_ssid *ssid) 384 { 385 struct bgscan_learn_data *data; 386 387 data = os_zalloc(sizeof(*data)); 388 if (data == NULL) 389 return NULL; 390 dl_list_init(&data->bss); 391 data->wpa_s = wpa_s; 392 data->ssid = ssid; 393 if (bgscan_learn_get_params(data, params) < 0) { 394 os_free(data->fname); 395 os_free(data); 396 return NULL; 397 } 398 if (data->short_interval <= 0) 399 data->short_interval = 30; 400 if (data->long_interval <= 0) 401 data->long_interval = 30; 402 403 if (bgscan_learn_load(data) < 0) { 404 os_free(data->fname); 405 os_free(data); 406 return NULL; 407 } 408 409 wpa_printf(MSG_DEBUG, "bgscan learn: Signal strength threshold %d " 410 "Short bgscan interval %d Long bgscan interval %d", 411 data->signal_threshold, data->short_interval, 412 data->long_interval); 413 414 if (data->signal_threshold && 415 wpa_drv_signal_monitor(wpa_s, data->signal_threshold, 4) < 0) { 416 wpa_printf(MSG_ERROR, "bgscan learn: Failed to enable " 417 "signal strength monitoring"); 418 } 419 420 data->supp_freqs = bgscan_learn_get_supp_freqs(wpa_s); 421 data->scan_interval = data->short_interval; 422 eloop_register_timeout(data->scan_interval, 0, bgscan_learn_timeout, 423 data, NULL); 424 425 /* 426 * This function is called immediately after an association, so it is 427 * reasonable to assume that a scan was completed recently. This makes 428 * us skip an immediate new scan in cases where the current signal 429 * level is below the bgscan threshold. 430 */ 431 os_get_time(&data->last_bgscan); 432 433 return data; 434 } 435 436 437 static void bgscan_learn_deinit(void *priv) 438 { 439 struct bgscan_learn_data *data = priv; 440 struct bgscan_learn_bss *bss, *n; 441 442 bgscan_learn_save(data); 443 eloop_cancel_timeout(bgscan_learn_timeout, data, NULL); 444 if (data->signal_threshold) 445 wpa_drv_signal_monitor(data->wpa_s, 0, 0); 446 os_free(data->fname); 447 dl_list_for_each_safe(bss, n, &data->bss, struct bgscan_learn_bss, 448 list) { 449 dl_list_del(&bss->list); 450 bss_free(bss); 451 } 452 os_free(data->supp_freqs); 453 os_free(data); 454 } 455 456 457 static int bgscan_learn_bss_match(struct bgscan_learn_data *data, 458 struct wpa_scan_res *bss) 459 { 460 const u8 *ie; 461 462 ie = wpa_scan_get_ie(bss, WLAN_EID_SSID); 463 if (ie == NULL) 464 return 0; 465 466 if (data->ssid->ssid_len != ie[1] || 467 os_memcmp(data->ssid->ssid, ie + 2, ie[1]) != 0) 468 return 0; /* SSID mismatch */ 469 470 return 1; 471 } 472 473 474 static int bgscan_learn_notify_scan(void *priv, 475 struct wpa_scan_results *scan_res) 476 { 477 struct bgscan_learn_data *data = priv; 478 size_t i, j; 479 #define MAX_BSS 50 480 u8 bssid[MAX_BSS * ETH_ALEN]; 481 size_t num_bssid = 0; 482 483 wpa_printf(MSG_DEBUG, "bgscan learn: scan result notification"); 484 485 eloop_cancel_timeout(bgscan_learn_timeout, data, NULL); 486 eloop_register_timeout(data->scan_interval, 0, bgscan_learn_timeout, 487 data, NULL); 488 489 for (i = 0; i < scan_res->num; i++) { 490 struct wpa_scan_res *res = scan_res->res[i]; 491 if (!bgscan_learn_bss_match(data, res)) 492 continue; 493 494 if (num_bssid < MAX_BSS) { 495 os_memcpy(bssid + num_bssid * ETH_ALEN, res->bssid, 496 ETH_ALEN); 497 num_bssid++; 498 } 499 } 500 wpa_printf(MSG_DEBUG, "bgscan learn: %u matching BSSes in scan " 501 "results", (unsigned int) num_bssid); 502 503 for (i = 0; i < scan_res->num; i++) { 504 struct wpa_scan_res *res = scan_res->res[i]; 505 struct bgscan_learn_bss *bss; 506 507 if (!bgscan_learn_bss_match(data, res)) 508 continue; 509 510 bss = bgscan_learn_get_bss(data, res->bssid); 511 if (bss && bss->freq != res->freq) { 512 wpa_printf(MSG_DEBUG, "bgscan learn: Update BSS " 513 MACSTR " freq %d -> %d", 514 MAC2STR(res->bssid), bss->freq, res->freq); 515 bss->freq = res->freq; 516 } else if (!bss) { 517 wpa_printf(MSG_DEBUG, "bgscan learn: Add BSS " MACSTR 518 " freq=%d", MAC2STR(res->bssid), res->freq); 519 bss = os_zalloc(sizeof(*bss)); 520 if (!bss) 521 continue; 522 os_memcpy(bss->bssid, res->bssid, ETH_ALEN); 523 bss->freq = res->freq; 524 dl_list_add(&data->bss, &bss->list); 525 } 526 527 for (j = 0; j < num_bssid; j++) { 528 u8 *addr = bssid + j * ETH_ALEN; 529 bgscan_learn_add_neighbor(bss, addr); 530 } 531 } 532 533 /* 534 * A more advanced bgscan could process scan results internally, select 535 * the BSS and request roam if needed. This sample uses the existing 536 * BSS/ESS selection routine. Change this to return 1 if selection is 537 * done inside the bgscan module. 538 */ 539 540 return 0; 541 } 542 543 544 static void bgscan_learn_notify_beacon_loss(void *priv) 545 { 546 wpa_printf(MSG_DEBUG, "bgscan learn: beacon loss"); 547 /* TODO: speed up background scanning */ 548 } 549 550 551 static void bgscan_learn_notify_signal_change(void *priv, int above, 552 int current_signal, 553 int current_noise, 554 int current_txrate) 555 { 556 struct bgscan_learn_data *data = priv; 557 int scan = 0; 558 struct os_time now; 559 560 if (data->short_interval == data->long_interval || 561 data->signal_threshold == 0) 562 return; 563 564 wpa_printf(MSG_DEBUG, "bgscan learn: signal level changed " 565 "(above=%d current_signal=%d current_noise=%d " 566 "current_txrate=%d)", above, current_signal, 567 current_noise, current_txrate); 568 if (data->scan_interval == data->long_interval && !above) { 569 wpa_printf(MSG_DEBUG, "bgscan learn: Start using short bgscan " 570 "interval"); 571 data->scan_interval = data->short_interval; 572 os_get_time(&now); 573 if (now.sec > data->last_bgscan.sec + 1) 574 scan = 1; 575 } else if (data->scan_interval == data->short_interval && above) { 576 wpa_printf(MSG_DEBUG, "bgscan learn: Start using long bgscan " 577 "interval"); 578 data->scan_interval = data->long_interval; 579 eloop_cancel_timeout(bgscan_learn_timeout, data, NULL); 580 eloop_register_timeout(data->scan_interval, 0, 581 bgscan_learn_timeout, data, NULL); 582 } else if (!above) { 583 /* 584 * Signal dropped further 4 dB. Request a new scan if we have 585 * not yet scanned in a while. 586 */ 587 os_get_time(&now); 588 if (now.sec > data->last_bgscan.sec + 10) 589 scan = 1; 590 } 591 592 if (scan) { 593 wpa_printf(MSG_DEBUG, "bgscan learn: Trigger immediate scan"); 594 eloop_cancel_timeout(bgscan_learn_timeout, data, NULL); 595 eloop_register_timeout(0, 0, bgscan_learn_timeout, data, NULL); 596 } 597 } 598 599 600 const struct bgscan_ops bgscan_learn_ops = { 601 .name = "learn", 602 .init = bgscan_learn_init, 603 .deinit = bgscan_learn_deinit, 604 .notify_scan = bgscan_learn_notify_scan, 605 .notify_beacon_loss = bgscan_learn_notify_beacon_loss, 606 .notify_signal_change = bgscan_learn_notify_signal_change, 607 }; 608