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_reltime 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; 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 } 268 269 270 static 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 } 316 317 318 static int bgscan_learn_get_params(struct bgscan_learn_data *data, 319 const char *params) 320 { 321 const char *pos; 322 323 data->short_interval = atoi(params); 324 325 pos = os_strchr(params, ':'); 326 if (pos == NULL) 327 return 0; 328 pos++; 329 data->signal_threshold = atoi(pos); 330 pos = os_strchr(pos, ':'); 331 if (pos == NULL) { 332 wpa_printf(MSG_ERROR, "bgscan learn: Missing scan interval " 333 "for high signal"); 334 return -1; 335 } 336 pos++; 337 data->long_interval = atoi(pos); 338 pos = os_strchr(pos, ':'); 339 if (pos) { 340 pos++; 341 data->fname = os_strdup(pos); 342 } 343 344 return 0; 345 } 346 347 348 static int * bgscan_learn_get_supp_freqs(struct wpa_supplicant *wpa_s) 349 { 350 struct hostapd_hw_modes *modes; 351 int i, j, *freqs = NULL, *n; 352 size_t count = 0; 353 354 modes = wpa_s->hw.modes; 355 if (modes == NULL) 356 return NULL; 357 358 for (i = 0; i < wpa_s->hw.num_modes; i++) { 359 for (j = 0; j < modes[i].num_channels; j++) { 360 if (modes[i].channels[j].flag & HOSTAPD_CHAN_DISABLED) 361 continue; 362 /* some hw modes (e.g. 11b & 11g) contain same freqs */ 363 if (in_array(freqs, modes[i].channels[j].freq)) 364 continue; 365 n = os_realloc_array(freqs, count + 2, sizeof(int)); 366 if (n == NULL) 367 continue; 368 369 freqs = n; 370 freqs[count] = modes[i].channels[j].freq; 371 count++; 372 freqs[count] = 0; 373 } 374 } 375 376 return freqs; 377 } 378 379 380 static void * bgscan_learn_init(struct wpa_supplicant *wpa_s, 381 const char *params, 382 const struct wpa_ssid *ssid) 383 { 384 struct bgscan_learn_data *data; 385 386 data = os_zalloc(sizeof(*data)); 387 if (data == NULL) 388 return NULL; 389 dl_list_init(&data->bss); 390 data->wpa_s = wpa_s; 391 data->ssid = ssid; 392 if (bgscan_learn_get_params(data, params) < 0) { 393 os_free(data->fname); 394 os_free(data); 395 return NULL; 396 } 397 if (data->short_interval <= 0) 398 data->short_interval = 30; 399 if (data->long_interval <= 0) 400 data->long_interval = 30; 401 402 if (bgscan_learn_load(data) < 0) { 403 os_free(data->fname); 404 os_free(data); 405 return NULL; 406 } 407 408 wpa_printf(MSG_DEBUG, "bgscan learn: Signal strength threshold %d " 409 "Short bgscan interval %d Long bgscan interval %d", 410 data->signal_threshold, data->short_interval, 411 data->long_interval); 412 413 if (data->signal_threshold && 414 wpa_drv_signal_monitor(wpa_s, data->signal_threshold, 4) < 0) { 415 wpa_printf(MSG_ERROR, "bgscan learn: Failed to enable " 416 "signal strength monitoring"); 417 } 418 419 data->supp_freqs = bgscan_learn_get_supp_freqs(wpa_s); 420 data->scan_interval = data->short_interval; 421 if (data->signal_threshold) { 422 /* Poll for signal info to set initial scan interval */ 423 struct wpa_signal_info siginfo; 424 if (wpa_drv_signal_poll(wpa_s, &siginfo) == 0 && 425 siginfo.current_signal >= data->signal_threshold) 426 data->scan_interval = data->long_interval; 427 } 428 429 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_reltime(&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_reltime 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_reltime(&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_reltime(&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
