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_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 (ret < 0 || ret >= msg + sizeof(msg) - pos) 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 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 } 349 350 351 static 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 } 381 382 383 static 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 } 445 446 447 static 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 } 465 466 467 static 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 } 482 483 484 static 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 } 552 553 554 static 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 } 559 560 561 static 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 } 608 609 610 const 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