wpa_supplicant/bss.c

   1 /*
   2  * BSS table
   3  * Copyright (c) 2009, Jouni Malinen <j@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 "utils/includes.h"
  16
  17 #include "utils/common.h"
  18 #include "utils/eloop.h"
  19 #include "common/ieee802_11_defs.h"
  20 #include "drivers/driver.h"
  21 #include "wpa_supplicant_i.h"
  22 #include "notify.h"
  23 #include "bss.h"
  24
  25
  26 #ifndef WPA_BSS_MAX_COUNT
  27 #define WPA_BSS_MAX_COUNT 200
  28 #endif /* WPA_BSS_MAX_COUNT */
  29
  30 /**
  31  * WPA_BSS_EXPIRATION_PERIOD - Period of expiration run in seconds
  32  */
  33 #define WPA_BSS_EXPIRATION_PERIOD 10
  34
  35 /**
  36  * WPA_BSS_EXPIRATION_AGE - BSS entry age after which it can be expired
  37  *
  38  * This value control the time in seconds after which a BSS entry gets removed
  39  * if it has not been updated or is not in use.
  40  */
  41 #define WPA_BSS_EXPIRATION_AGE 180
  42
  43 /**
  44  * WPA_BSS_EXPIRATION_SCAN_COUNT - Expire BSS after number of scans
  45  *
  46  * If the BSS entry has not been seen in this many scans, it will be removed.
  47  * Value 1 means that the entry is removed after the first scan without the
  48  * BSSID being seen. Larger values can be used to avoid BSS entries
  49  * disappearing if they are not visible in every scan (e.g., low signal quality
  50  * or interference).
  51  */
  52 #define WPA_BSS_EXPIRATION_SCAN_COUNT 2
  53
  54
  55 static void wpa_bss_remove(struct wpa_supplicant *wpa_s, struct wpa_bss *bss)
  56 {
  57         dl_list_del(&bss->list);
  58         dl_list_del(&bss->list_id);
  59         wpa_s->num_bss--;
  60         wpa_printf(MSG_DEBUG, "BSS: Remove id %u BSSID " MACSTR " SSID '%s'",
  61                    bss->id, MAC2STR(bss->bssid),
  62                    wpa_ssid_txt(bss->ssid, bss->ssid_len));
  63         wpas_notify_bss_removed(wpa_s, bss->bssid, bss->id);
  64         os_free(bss);
  65 }
  66
  67
  68 static struct wpa_bss * wpa_bss_get(struct wpa_supplicant *wpa_s,
  69                                     const u8 *bssid, const u8 *ssid,
  70                                     size_t ssid_len)
  71 {
  72         struct wpa_bss *bss;
  73         dl_list_for_each(bss, &wpa_s->bss, struct wpa_bss, list) {
  74                 if (os_memcmp(bss->bssid, bssid, ETH_ALEN) == 0 &&
  75                     bss->ssid_len == ssid_len &&
  76                     os_memcmp(bss->ssid, ssid, ssid_len) == 0)
  77                         return bss;
  78         }
  79         return NULL;
  80 }
  81
  82
  83 static void wpa_bss_copy_res(struct wpa_bss *dst, struct wpa_scan_res *src)
  84 {
  85         os_time_t usec;
  86
  87         dst->flags = src->flags;
  88         os_memcpy(dst->bssid, src->bssid, ETH_ALEN);
  89         dst->freq = src->freq;
  90         dst->beacon_int = src->beacon_int;
  91         dst->caps = src->caps;
  92         dst->qual = src->qual;
  93         dst->noise = src->noise;
  94         dst->level = src->level;
  95         dst->tsf = src->tsf;
  96
  97         os_get_time(&dst->last_update);
  98         dst->last_update.sec -= src->age / 1000;
  99         usec = (src->age % 1000) * 1000;
 100         if (dst->last_update.usec < usec) {
 101                 dst->last_update.sec--;
 102                 dst->last_update.usec += 1000000;
 103         }
 104         dst->last_update.usec -= usec;
 105 }
 106
 107
 108 static void wpa_bss_add(struct wpa_supplicant *wpa_s,
 109                         const u8 *ssid, size_t ssid_len,
 110                         struct wpa_scan_res *res)
 111 {
 112         struct wpa_bss *bss;
 113
 114         bss = os_zalloc(sizeof(*bss) + res->ie_len);
 115         if (bss == NULL)
 116                 return;
 117         bss->id = wpa_s->bss_next_id++;
 118         bss->last_update_idx = wpa_s->bss_update_idx;
 119         wpa_bss_copy_res(bss, res);
 120         os_memcpy(bss->ssid, ssid, ssid_len);
 121         bss->ssid_len = ssid_len;
 122         bss->ie_len = res->ie_len;
 123         os_memcpy(bss + 1, res + 1, res->ie_len);
 124
 125         dl_list_add_tail(&wpa_s->bss, &bss->list);
 126         dl_list_add_tail(&wpa_s->bss_id, &bss->list_id);
 127         wpa_s->num_bss++;
 128         wpa_printf(MSG_DEBUG, "BSS: Add new id %u BSSID " MACSTR " SSID '%s'",
 129                    bss->id, MAC2STR(bss->bssid), wpa_ssid_txt(ssid, ssid_len));
 130         wpas_notify_bss_added(wpa_s, bss->bssid, bss->id);
 131         if (wpa_s->num_bss > WPA_BSS_MAX_COUNT) {
 132                 /* Remove the oldest entry */
 133                 wpa_bss_remove(wpa_s, dl_list_first(&wpa_s->bss,
 134                                                     struct wpa_bss, list));
 135         }
 136 }
 137
 138
 139 static void wpa_bss_update(struct wpa_supplicant *wpa_s, struct wpa_bss *bss,
 140                            struct wpa_scan_res *res)
 141 {
 142         bss->scan_miss_count = 0;
 143         bss->last_update_idx = wpa_s->bss_update_idx;
 144         wpa_bss_copy_res(bss, res);
 145         /* Move the entry to the end of the list */
 146         dl_list_del(&bss->list);
 147         if (bss->ie_len >= res->ie_len) {
 148                 os_memcpy(bss + 1, res + 1, res->ie_len);
 149                 bss->ie_len = res->ie_len;
 150         } else {
 151                 struct wpa_bss *nbss;
 152                 nbss = os_realloc(bss, sizeof(*bss) + res->ie_len);
 153                 if (nbss) {
 154                         bss = nbss;
 155                         os_memcpy(bss + 1, res + 1, res->ie_len);
 156                         bss->ie_len = res->ie_len;
 157                 }
 158         }
 159         dl_list_add_tail(&wpa_s->bss, &bss->list);
 160 }
 161
 162
 163 void wpa_bss_update_start(struct wpa_supplicant *wpa_s)
 164 {
 165         wpa_s->bss_update_idx++;
 166         wpa_printf(MSG_DEBUG, "BSS: Start scan result update %u",
 167                    wpa_s->bss_update_idx);
 168 }
 169
 170
 171 void wpa_bss_update_scan_res(struct wpa_supplicant *wpa_s,
 172                              struct wpa_scan_res *res)
 173 {
 174         const u8 *ssid;
 175         struct wpa_bss *bss;
 176
 177         ssid = wpa_scan_get_ie(res, WLAN_EID_SSID);
 178         if (ssid == NULL) {
 179                 wpa_printf(MSG_DEBUG, "BSS: No SSID IE included for " MACSTR,
 180                            MAC2STR(res->bssid));
 181                 return;
 182         }
 183         if (ssid[1] > 32) {
 184                 wpa_printf(MSG_DEBUG, "BSS: Too long SSID IE included for "
 185                            MACSTR, MAC2STR(res->bssid));
 186                 return;
 187         }
 188
 189         /* TODO: add option for ignoring BSSes we are not interested in
 190          * (to save memory) */
 191         bss = wpa_bss_get(wpa_s, res->bssid, ssid + 2, ssid[1]);
 192         if (bss == NULL)
 193                 wpa_bss_add(wpa_s, ssid + 2, ssid[1], res);
 194         else
 195                 wpa_bss_update(wpa_s, bss, res);
 196 }
 197
 198
 199 void wpa_bss_update_end(struct wpa_supplicant *wpa_s)
 200 {
 201         struct wpa_bss *bss, *n;
 202
 203         /* TODO: expire only entries that were on the scanned frequencies/SSIDs
 204          * list; need to get info from driver about scanned frequencies and
 205          * SSIDs to be able to figure out which entries should be expired based
 206          * on this */
 207
 208         dl_list_for_each_safe(bss, n, &wpa_s->bss, struct wpa_bss, list) {
 209                 if (bss->last_update_idx < wpa_s->bss_update_idx)
 210                         bss->scan_miss_count++;
 211                 if (bss->scan_miss_count >= WPA_BSS_EXPIRATION_SCAN_COUNT) {
 212                         wpa_printf(MSG_DEBUG, "BSS: Expire BSS %u due to no "
 213                                    "match in scan", bss->id);
 214                         wpa_bss_remove(wpa_s, bss);
 215                 }
 216         }
 217 }
 218
 219
 220 static void wpa_bss_timeout(void *eloop_ctx, void *timeout_ctx)
 221 {
 222         struct wpa_supplicant *wpa_s = eloop_ctx;
 223         struct wpa_bss *bss, *n;
 224         struct os_time t;
 225
 226         if (dl_list_empty(&wpa_s->bss))
 227                 return;
 228
 229         os_get_time(&t);
 230         t.sec -= WPA_BSS_EXPIRATION_AGE;
 231
 232         dl_list_for_each_safe(bss, n, &wpa_s->bss, struct wpa_bss, list) {
 233                 if (os_memcmp(bss->bssid, wpa_s->bssid, ETH_ALEN) == 0 ||
 234                     os_memcmp(bss->bssid, wpa_s->pending_bssid, ETH_ALEN) == 0)
 235                         continue; /* do not expire BSSes that are in use */
 236
 237                 if (os_time_before(&bss->last_update, &t)) {
 238                         wpa_printf(MSG_DEBUG, "BSS: Expire BSS %u due to age",
 239                                    bss->id);
 240                         wpa_bss_remove(wpa_s, bss);
 241                 } else
 242                         break;
 243         }
 244         eloop_register_timeout(WPA_BSS_EXPIRATION_PERIOD, 0,
 245                                wpa_bss_timeout, wpa_s, NULL);
 246 }
 247
 248
 249 int wpa_bss_init(struct wpa_supplicant *wpa_s)
 250 {
 251         dl_list_init(&wpa_s->bss);
 252         dl_list_init(&wpa_s->bss_id);
 253         eloop_register_timeout(WPA_BSS_EXPIRATION_PERIOD, 0,
 254                                wpa_bss_timeout, wpa_s, NULL);
 255         return 0;
 256 }
 257
 258
 259 void wpa_bss_deinit(struct wpa_supplicant *wpa_s)
 260 {
 261         struct wpa_bss *bss, *n;
 262         eloop_cancel_timeout(wpa_bss_timeout, wpa_s, NULL);
 263         if (wpa_s->bss.next == NULL)
 264                 return; /* BSS table not yet initialized */
 265         dl_list_for_each_safe(bss, n, &wpa_s->bss, struct wpa_bss, list)
 266                 wpa_bss_remove(wpa_s, bss);
 267 }
 268
 269
 270 struct wpa_bss * wpa_bss_get_bssid(struct wpa_supplicant *wpa_s,
 271                                    const u8 *bssid)
 272 {
 273         struct wpa_bss *bss;
 274         dl_list_for_each(bss, &wpa_s->bss, struct wpa_bss, list) {
 275                 if (os_memcmp(bss->bssid, bssid, ETH_ALEN) == 0)
 276                         return bss;
 277         }
 278         return NULL;
 279 }
 280
 281
 282 struct wpa_bss * wpa_bss_get_id(struct wpa_supplicant *wpa_s, unsigned int id)
 283 {
 284         struct wpa_bss *bss;
 285         dl_list_for_each(bss, &wpa_s->bss, struct wpa_bss, list) {
 286                 if (bss->id == id)
 287                         return bss;
 288         }
 289         return NULL;
 290 }
 291
 292
 293 const u8 * wpa_bss_get_ie(const struct wpa_bss *bss, u8 ie)
 294 {
 295         const u8 *end, *pos;
 296
 297         pos = (const u8 *) (bss + 1);
 298         end = pos + bss->ie_len;
 299
 300         while (pos + 1 < end) {
 301                 if (pos + 2 + pos[1] > end)
 302                         break;
 303                 if (pos[0] == ie)
 304                         return pos;
 305                 pos += 2 + pos[1];
 306         }
 307
 308         return NULL;
 309 }
 310
 311
 312 const u8 * wpa_bss_get_vendor_ie(const struct wpa_bss *bss, u32 vendor_type)
 313 {
 314         const u8 *end, *pos;
 315
 316         pos = (const u8 *) (bss + 1);
 317         end = pos + bss->ie_len;
 318
 319         while (pos + 1 < end) {
 320                 if (pos + 2 + pos[1] > end)
 321                         break;
 322                 if (pos[0] == WLAN_EID_VENDOR_SPECIFIC && pos[1] >= 4 &&
 323                     vendor_type == WPA_GET_BE32(&pos[2]))
 324                         return pos;
 325                 pos += 2 + pos[1];
 326         }
 327
 328         return NULL;
 329 }
 330
 331
 332 struct wpabuf * wpa_bss_get_vendor_ie_multi(const struct wpa_bss *bss,
 333                                             u32 vendor_type)
 334 {
 335         struct wpabuf *buf;
 336         const u8 *end, *pos;
 337
 338         buf = wpabuf_alloc(bss->ie_len);
 339         if (buf == NULL)
 340                 return NULL;
 341
 342         pos = (const u8 *) (bss + 1);
 343         end = pos + bss->ie_len;
 344
 345         while (pos + 1 < end) {
 346                 if (pos + 2 + pos[1] > end)
 347                         break;
 348                 if (pos[0] == WLAN_EID_VENDOR_SPECIFIC && pos[1] >= 4 &&
 349                     vendor_type == WPA_GET_BE32(&pos[2]))
 350                         wpabuf_put_data(buf, pos + 2 + 4, pos[1] - 4);
 351                 pos += 2 + pos[1];
 352         }
 353
 354         if (wpabuf_len(buf) == 0) {
 355                 wpabuf_free(buf);
 356                 buf = NULL;
 357         }
 358
 359         return buf;
 360 }
 361
 362
 363 int wpa_bss_get_max_rate(const struct wpa_bss *bss)
 364 {
 365         int rate = 0;
 366         const u8 *ie;
 367         int i;
 368
 369         ie = wpa_bss_get_ie(bss, WLAN_EID_SUPP_RATES);
 370         for (i = 0; ie && i < ie[1]; i++) {
 371                 if ((ie[i + 2] & 0x7f) > rate)
 372                         rate = ie[i + 2] & 0x7f;
 373         }
 374
 375         ie = wpa_bss_get_ie(bss, WLAN_EID_EXT_SUPP_RATES);
 376         for (i = 0; ie && i < ie[1]; i++) {
 377                 if ((ie[i + 2] & 0x7f) > rate)
 378                         rate = ie[i + 2] & 0x7f;
 379         }
 380
 381         return rate;
 382 }