1 /* 2 * WPA Supplicant - background scan and roaming module: learn 3 * Copyright (c) 2009-2010, Jouni Malinen <j (at) 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(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(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 idx = 0; 247 if (!in_array(freqs, data->supp_freqs[idx])) { 248 wpa_printf(MSG_DEBUG, "bgscan learn: Probe new freq " 249 "%u", data->supp_freqs[idx]); 250 data->probe_idx = idx; 251 n = os_realloc(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 } 263 264 return freqs; 265 } 266 267 268 static void bgscan_learn_timeout(void *eloop_ctx, void *timeout_ctx) 269 { 270 struct bgscan_learn_data *data = eloop_ctx; 271 struct wpa_supplicant *wpa_s = data->wpa_s; 272 struct wpa_driver_scan_params params; 273 int *freqs = NULL; 274 size_t count, i; 275 char msg[100], *pos; 276 277 os_memset(¶ms, 0, sizeof(params)); 278 params.num_ssids = 1; 279 params.ssids[0].ssid = data->ssid->ssid; 280 params.ssids[0].ssid_len = data->ssid->ssid_len; 281 if (data->ssid->scan_freq) 282 params.freqs = data->ssid->scan_freq; 283 else { 284 freqs = bgscan_learn_get_freqs(data, &count); 285 wpa_printf(MSG_DEBUG, "bgscan learn: BSSes in this ESS have " 286 "been seen on %u channels", (unsigned int) count); 287 freqs = bgscan_learn_get_probe_freq(data, freqs, count); 288 289 msg[0] = '\0'; 290 pos = msg; 291 for (i = 0; freqs && freqs[i]; i++) { 292 int ret; 293 ret = os_snprintf(pos, msg + sizeof(msg) - pos, " %d", 294 freqs[i]); 295 if (ret < 0 || ret >= msg + sizeof(msg) - pos) 296 break; 297 pos += ret; 298 } 299 pos[0] = '\0'; 300 wpa_printf(MSG_DEBUG, "bgscan learn: Scanning frequencies:%s", 301 msg); 302 params.freqs = freqs; 303 } 304 305 wpa_printf(MSG_DEBUG, "bgscan learn: Request a background scan"); 306 if (wpa_supplicant_trigger_scan(wpa_s, ¶ms)) { 307 wpa_printf(MSG_DEBUG, "bgscan learn: Failed to trigger scan"); 308 eloop_register_timeout(data->scan_interval, 0, 309 bgscan_learn_timeout, data, NULL); 310 } else 311 os_get_time(&data->last_bgscan); 312 os_free(freqs); 313 } 314 315 316 static int bgscan_learn_get_params(struct bgscan_learn_data *data, 317 const char *params) 318 { 319 const char *pos; 320 321 if (params == NULL) 322 return 0; 323 324 data->short_interval = atoi(params); 325 326 pos = os_strchr(params, ':'); 327 if (pos == NULL) 328 return 0; 329 pos++; 330 data->signal_threshold = atoi(pos); 331 pos = os_strchr(pos, ':'); 332 if (pos == NULL) { 333 wpa_printf(MSG_ERROR, "bgscan learn: Missing scan interval " 334 "for high signal"); 335 return -1; 336 } 337 pos++; 338 data->long_interval = atoi(pos); 339 pos = os_strchr(pos, ':'); 340 if (pos) { 341 pos++; 342 data->fname = os_strdup(pos); 343 } 344 345 return 0; 346 } 347 348 349 static int * bgscan_learn_get_supp_freqs(struct wpa_supplicant *wpa_s) 350 { 351 struct hostapd_hw_modes *modes; 352 int i, j, *freqs = NULL, *n; 353 size_t count = 0; 354 355 modes = wpa_s->hw.modes; 356 if (modes == NULL) 357 return NULL; 358 359 for (i = 0; i < wpa_s->hw.num_modes; i++) { 360 for (j = 0; j < modes[i].num_channels; j++) { 361 if (modes[i].channels[j].flag & HOSTAPD_CHAN_DISABLED) 362 continue; 363 n = os_realloc(freqs, (count + 2) * sizeof(int)); 364 if (n == NULL) 365 continue; 366 367 freqs = n; 368 freqs[count] = modes[i].channels[j].freq; 369 count++; 370 freqs[count] = 0; 371 } 372 } 373 374 return freqs; 375 } 376 377 378 static void * bgscan_learn_init(struct wpa_supplicant *wpa_s, 379 const char *params, 380 const struct wpa_ssid *ssid) 381 { 382 struct bgscan_learn_data *data; 383 384 data = os_zalloc(sizeof(*data)); 385 if (data == NULL) 386 return NULL; 387 dl_list_init(&data->bss); 388 data->wpa_s = wpa_s; 389 data->ssid = ssid; 390 if (bgscan_learn_get_params(data, params) < 0) { 391 os_free(data->fname); 392 os_free(data); 393 return NULL; 394 } 395 if (data->short_interval <= 0) 396 data->short_interval = 30; 397 if (data->long_interval <= 0) 398 data->long_interval = 30; 399 400 if (bgscan_learn_load(data) < 0) { 401 os_free(data->fname); 402 os_free(data); 403 return NULL; 404 } 405 406 wpa_printf(MSG_DEBUG, "bgscan learn: Signal strength threshold %d " 407 "Short bgscan interval %d Long bgscan interval %d", 408 data->signal_threshold, data->short_interval, 409 data->long_interval); 410 411 if (data->signal_threshold && 412 wpa_drv_signal_monitor(wpa_s, data->signal_threshold, 4) < 0) { 413 wpa_printf(MSG_ERROR, "bgscan learn: Failed to enable " 414 "signal strength monitoring"); 415 } 416 417 data->supp_freqs = bgscan_learn_get_supp_freqs(wpa_s); 418 data->scan_interval = data->short_interval; 419 eloop_register_timeout(data->scan_interval, 0, bgscan_learn_timeout, 420 data, NULL); 421 422 /* 423 * This function is called immediately after an association, so it is 424 * reasonable to assume that a scan was completed recently. This makes 425 * us skip an immediate new scan in cases where the current signal 426 * level is below the bgscan threshold. 427 */ 428 os_get_time(&data->last_bgscan); 429 430 return data; 431 } 432 433 434 static void bgscan_learn_deinit(void *priv) 435 { 436 struct bgscan_learn_data *data = priv; 437 struct bgscan_learn_bss *bss, *n; 438 439 bgscan_learn_save(data); 440 eloop_cancel_timeout(bgscan_learn_timeout, data, NULL); 441 if (data->signal_threshold) 442 wpa_drv_signal_monitor(data->wpa_s, 0, 0); 443 os_free(data->fname); 444 dl_list_for_each_safe(bss, n, &data->bss, struct bgscan_learn_bss, 445 list) { 446 dl_list_del(&bss->list); 447 bss_free(bss); 448 } 449 os_free(data->supp_freqs); 450 os_free(data); 451 } 452 453 454 static int bgscan_learn_bss_match(struct bgscan_learn_data *data, 455 struct wpa_scan_res *bss) 456 { 457 const u8 *ie; 458 459 ie = wpa_scan_get_ie(bss, WLAN_EID_SSID); 460 if (ie == NULL) 461 return 0; 462 463 if (data->ssid->ssid_len != ie[1] || 464 os_memcmp(data->ssid->ssid, ie + 2, ie[1]) != 0) 465 return 0; /* SSID mismatch */ 466 467 return 1; 468 } 469 470 471 static int bgscan_learn_notify_scan(void *priv, 472 struct wpa_scan_results *scan_res) 473 { 474 struct bgscan_learn_data *data = priv; 475 size_t i, j; 476 #define MAX_BSS 50 477 u8 bssid[MAX_BSS * ETH_ALEN]; 478 size_t num_bssid = 0; 479 480 wpa_printf(MSG_DEBUG, "bgscan learn: scan result notification"); 481 482 eloop_cancel_timeout(bgscan_learn_timeout, data, NULL); 483 eloop_register_timeout(data->scan_interval, 0, bgscan_learn_timeout, 484 data, NULL); 485 486 for (i = 0; i < scan_res->num; i++) { 487 struct wpa_scan_res *res = scan_res->res[i]; 488 if (!bgscan_learn_bss_match(data, res)) 489 continue; 490 491 if (num_bssid < MAX_BSS) { 492 os_memcpy(bssid + num_bssid * ETH_ALEN, res->bssid, 493 ETH_ALEN); 494 num_bssid++; 495 } 496 } 497 wpa_printf(MSG_DEBUG, "bgscan learn: %u matching BSSes in scan " 498 "results", (unsigned int) num_bssid); 499 500 for (i = 0; i < scan_res->num; i++) { 501 struct wpa_scan_res *res = scan_res->res[i]; 502 struct bgscan_learn_bss *bss; 503 504 if (!bgscan_learn_bss_match(data, res)) 505 continue; 506 507 bss = bgscan_learn_get_bss(data, res->bssid); 508 if (bss && bss->freq != res->freq) { 509 wpa_printf(MSG_DEBUG, "bgscan learn: Update BSS " 510 MACSTR " freq %d -> %d", 511 MAC2STR(res->bssid), bss->freq, res->freq); 512 bss->freq = res->freq; 513 } else if (!bss) { 514 wpa_printf(MSG_DEBUG, "bgscan learn: Add BSS " MACSTR 515 " freq=%d", MAC2STR(res->bssid), res->freq); 516 bss = os_zalloc(sizeof(*bss)); 517 if (!bss) 518 continue; 519 os_memcpy(bss->bssid, res->bssid, ETH_ALEN); 520 bss->freq = res->freq; 521 dl_list_add(&data->bss, &bss->list); 522 } 523 524 for (j = 0; j < num_bssid; j++) { 525 u8 *addr = bssid + j * ETH_ALEN; 526 bgscan_learn_add_neighbor(bss, addr); 527 } 528 } 529 530 /* 531 * A more advanced bgscan could process scan results internally, select 532 * the BSS and request roam if needed. This sample uses the existing 533 * BSS/ESS selection routine. Change this to return 1 if selection is 534 * done inside the bgscan module. 535 */ 536 537 return 0; 538 } 539 540 541 static void bgscan_learn_notify_beacon_loss(void *priv) 542 { 543 wpa_printf(MSG_DEBUG, "bgscan learn: beacon loss"); 544 /* TODO: speed up background scanning */ 545 } 546 547 548 static void bgscan_learn_notify_signal_change(void *priv, int above, 549 int current_signal, 550 int current_noise, 551 int current_txrate) 552 { 553 struct bgscan_learn_data *data = priv; 554 int scan = 0; 555 struct os_time now; 556 557 if (data->short_interval == data->long_interval || 558 data->signal_threshold == 0) 559 return; 560 561 wpa_printf(MSG_DEBUG, "bgscan learn: signal level changed " 562 "(above=%d current_signal=%d current_noise=%d " 563 "current_txrate=%d)", above, current_signal, 564 current_noise, current_txrate); 565 if (data->scan_interval == data->long_interval && !above) { 566 wpa_printf(MSG_DEBUG, "bgscan learn: Start using short bgscan " 567 "interval"); 568 data->scan_interval = data->short_interval; 569 os_get_time(&now); 570 if (now.sec > data->last_bgscan.sec + 1) 571 scan = 1; 572 } else if (data->scan_interval == data->short_interval && above) { 573 wpa_printf(MSG_DEBUG, "bgscan learn: Start using long bgscan " 574 "interval"); 575 data->scan_interval = data->long_interval; 576 eloop_cancel_timeout(bgscan_learn_timeout, data, NULL); 577 eloop_register_timeout(data->scan_interval, 0, 578 bgscan_learn_timeout, data, NULL); 579 } else if (!above) { 580 /* 581 * Signal dropped further 4 dB. Request a new scan if we have 582 * not yet scanned in a while. 583 */ 584 os_get_time(&now); 585 if (now.sec > data->last_bgscan.sec + 10) 586 scan = 1; 587 } 588 589 if (scan) { 590 wpa_printf(MSG_DEBUG, "bgscan learn: Trigger immediate scan"); 591 eloop_cancel_timeout(bgscan_learn_timeout, data, NULL); 592 eloop_register_timeout(0, 0, bgscan_learn_timeout, data, NULL); 593 } 594 } 595 596 597 const struct bgscan_ops bgscan_learn_ops = { 598 .name = "learn", 599 .init = bgscan_learn_init, 600 .deinit = bgscan_learn_deinit, 601 .notify_scan = bgscan_learn_notify_scan, 602 .notify_beacon_loss = bgscan_learn_notify_beacon_loss, 603 .notify_signal_change = bgscan_learn_notify_signal_change, 604 }; 605
