src/ap/beacon.c

   1 /*
   2  * hostapd / IEEE 802.11 Management: Beacon and Probe Request/Response
   3  * Copyright (c) 2002-2004, Instant802 Networks, Inc.
   4  * Copyright (c) 2005-2006, Devicescape Software, Inc.
   5  * Copyright (c) 2008-2009, Jouni Malinen <j@w1.fi>
   6  *
   7  * This program is free software; you can redistribute it and/or modify
   8  * it under the terms of the GNU General Public License version 2 as
   9  * published by the Free Software Foundation.
  10  *
  11  * Alternatively, this software may be distributed under the terms of BSD
  12  * license.
  13  *
  14  * See README and COPYING for more details.
  15  */
  16
  17 #include "utils/includes.h"
  18
  19 #ifndef CONFIG_NATIVE_WINDOWS
  20
  21 #include "utils/common.h"
  22 #include "common/ieee802_11_defs.h"
  23 #include "common/ieee802_11_common.h"
  24 #include "drivers/driver.h"
  25 #include "hostapd.h"
  26 #include "ieee802_11.h"
  27 #include "wpa_auth.h"
  28 #include "wmm.h"
  29 #include "ap_config.h"
  30 #include "sta_info.h"
  31 #include "beacon.h"
  32
  33
  34 static u8 ieee802_11_erp_info(struct hostapd_data *hapd)
  35 {
  36         u8 erp = 0;
  37
  38         if (hapd->iface->current_mode == NULL ||
  39             hapd->iface->current_mode->mode != HOSTAPD_MODE_IEEE80211G)
  40                 return 0;
  41
  42         switch (hapd->iconf->cts_protection_type) {
  43         case CTS_PROTECTION_FORCE_ENABLED:
  44                 erp |= ERP_INFO_NON_ERP_PRESENT | ERP_INFO_USE_PROTECTION;
  45                 break;
  46         case CTS_PROTECTION_FORCE_DISABLED:
  47                 erp = 0;
  48                 break;
  49         case CTS_PROTECTION_AUTOMATIC:
  50                 if (hapd->iface->olbc)
  51                         erp |= ERP_INFO_USE_PROTECTION;
  52                 /* continue */
  53         case CTS_PROTECTION_AUTOMATIC_NO_OLBC:
  54                 if (hapd->iface->num_sta_non_erp > 0) {
  55                         erp |= ERP_INFO_NON_ERP_PRESENT |
  56                                 ERP_INFO_USE_PROTECTION;
  57                 }
  58                 break;
  59         }
  60         if (hapd->iface->num_sta_no_short_preamble > 0)
  61                 erp |= ERP_INFO_BARKER_PREAMBLE_MODE;
  62
  63         return erp;
  64 }
  65
  66
  67 static u8 * hostapd_eid_ds_params(struct hostapd_data *hapd, u8 *eid)
  68 {
  69         *eid++ = WLAN_EID_DS_PARAMS;
  70         *eid++ = 1;
  71         *eid++ = hapd->iconf->channel;
  72         return eid;
  73 }
  74
  75
  76 static u8 * hostapd_eid_erp_info(struct hostapd_data *hapd, u8 *eid)
  77 {
  78         if (hapd->iface->current_mode == NULL ||
  79             hapd->iface->current_mode->mode != HOSTAPD_MODE_IEEE80211G)
  80                 return eid;
  81
  82         /* Set NonERP_present and use_protection bits if there
  83          * are any associated NonERP stations. */
  84         /* TODO: use_protection bit can be set to zero even if
  85          * there are NonERP stations present. This optimization
  86          * might be useful if NonERP stations are "quiet".
  87          * See 802.11g/D6 E-1 for recommended practice.
  88          * In addition, Non ERP present might be set, if AP detects Non ERP
  89          * operation on other APs. */
  90
  91         /* Add ERP Information element */
  92         *eid++ = WLAN_EID_ERP_INFO;
  93         *eid++ = 1;
  94         *eid++ = ieee802_11_erp_info(hapd);
  95
  96         return eid;
  97 }
  98
  99
 100 static u8 * hostapd_eid_country_add(u8 *pos, u8 *end, int chan_spacing,
 101                                     struct hostapd_channel_data *start,
 102                                     struct hostapd_channel_data *prev)
 103 {
 104         if (end - pos < 3)
 105                 return pos;
 106
 107         /* first channel number */
 108         *pos++ = start->chan;
 109         /* number of channels */
 110         *pos++ = (prev->chan - start->chan) / chan_spacing + 1;
 111         /* maximum transmit power level */
 112         *pos++ = start->max_tx_power;
 113
 114         return pos;
 115 }
 116
 117
 118 static u8 * hostapd_eid_country(struct hostapd_data *hapd, u8 *eid,
 119                                 int max_len)
 120 {
 121         u8 *pos = eid;
 122         u8 *end = eid + max_len;
 123         int i;
 124         struct hostapd_hw_modes *mode;
 125         struct hostapd_channel_data *start, *prev;
 126         int chan_spacing = 1;
 127
 128         if (!hapd->iconf->ieee80211d || max_len < 6 ||
 129             hapd->iface->current_mode == NULL)
 130                 return eid;
 131
 132         *pos++ = WLAN_EID_COUNTRY;
 133         pos++; /* length will be set later */
 134         os_memcpy(pos, hapd->iconf->country, 3); /* e.g., 'US ' */
 135         pos += 3;
 136
 137         mode = hapd->iface->current_mode;
 138         if (mode->mode == HOSTAPD_MODE_IEEE80211A)
 139                 chan_spacing = 4;
 140
 141         start = prev = NULL;
 142         for (i = 0; i < mode->num_channels; i++) {
 143                 struct hostapd_channel_data *chan = &mode->channels[i];
 144                 if (chan->flag & HOSTAPD_CHAN_DISABLED)
 145                         continue;
 146                 if (start && prev &&
 147                     prev->chan + chan_spacing == chan->chan &&
 148                     start->max_tx_power == chan->max_tx_power) {
 149                         prev = chan;
 150                         continue; /* can use same entry */
 151                 }
 152
 153                 if (start) {
 154                         pos = hostapd_eid_country_add(pos, end, chan_spacing,
 155                                                       start, prev);
 156                         start = NULL;
 157                 }
 158
 159                 /* Start new group */
 160                 start = prev = chan;
 161         }
 162
 163         if (start) {
 164                 pos = hostapd_eid_country_add(pos, end, chan_spacing,
 165                                               start, prev);
 166         }
 167
 168         if ((pos - eid) & 1) {
 169                 if (end - pos < 1)
 170                         return eid;
 171                 *pos++ = 0; /* pad for 16-bit alignment */
 172         }
 173
 174         eid[1] = (pos - eid) - 2;
 175
 176         return pos;
 177 }
 178
 179
 180 static u8 * hostapd_eid_wpa(struct hostapd_data *hapd, u8 *eid, size_t len,
 181                             struct sta_info *sta)
 182 {
 183         const u8 *ie;
 184         size_t ielen;
 185
 186         ie = wpa_auth_get_wpa_ie(hapd->wpa_auth, &ielen);
 187         if (ie == NULL || ielen > len)
 188                 return eid;
 189
 190         os_memcpy(eid, ie, ielen);
 191         return eid + ielen;
 192 }
 193
 194
 195 void handle_probe_req(struct hostapd_data *hapd,
 196                       const struct ieee80211_mgmt *mgmt, size_t len)
 197 {
 198         struct ieee80211_mgmt *resp;
 199         struct ieee802_11_elems elems;
 200         char *ssid;
 201         u8 *pos, *epos;
 202         const u8 *ie;
 203         size_t ssid_len, ie_len;
 204         struct sta_info *sta = NULL;
 205         size_t i;
 206
 207         ie = mgmt->u.probe_req.variable;
 208         ie_len = len - (IEEE80211_HDRLEN + sizeof(mgmt->u.probe_req));
 209
 210         for (i = 0; hapd->probereq_cb && i < hapd->num_probereq_cb; i++)
 211                 hapd->probereq_cb[i].cb(hapd->probereq_cb[i].ctx,
 212                                         mgmt->sa, ie, ie_len);
 213
 214         if (!hapd->iconf->send_probe_response)
 215                 return;
 216
 217         if (ieee802_11_parse_elems(ie, ie_len, &elems, 0) == ParseFailed) {
 218                 wpa_printf(MSG_DEBUG, "Could not parse ProbeReq from " MACSTR,
 219                            MAC2STR(mgmt->sa));
 220                 return;
 221         }
 222
 223         ssid = NULL;
 224         ssid_len = 0;
 225
 226         if ((!elems.ssid || !elems.supp_rates)) {
 227                 wpa_printf(MSG_DEBUG, "STA " MACSTR " sent probe request "
 228                            "without SSID or supported rates element",
 229                            MAC2STR(mgmt->sa));
 230                 return;
 231         }
 232
 233         if (hapd->conf->ignore_broadcast_ssid && elems.ssid_len == 0) {
 234                 wpa_printf(MSG_MSGDUMP, "Probe Request from " MACSTR " for "
 235                            "broadcast SSID ignored", MAC2STR(mgmt->sa));
 236                 return;
 237         }
 238
 239         sta = ap_get_sta(hapd, mgmt->sa);
 240
 241         if (elems.ssid_len == 0 ||
 242             (elems.ssid_len == hapd->conf->ssid.ssid_len &&
 243              os_memcmp(elems.ssid, hapd->conf->ssid.ssid, elems.ssid_len) ==
 244              0)) {
 245                 ssid = hapd->conf->ssid.ssid;
 246                 ssid_len = hapd->conf->ssid.ssid_len;
 247                 if (sta)
 248                         sta->ssid_probe = &hapd->conf->ssid;
 249         }
 250
 251         if (!ssid) {
 252                 if (!(mgmt->da[0] & 0x01)) {
 253                         char ssid_txt[33];
 254                         ieee802_11_print_ssid(ssid_txt, elems.ssid,
 255                                               elems.ssid_len);
 256                         wpa_printf(MSG_MSGDUMP, "Probe Request from " MACSTR
 257                                    " for foreign SSID '%s'",
 258                                    MAC2STR(mgmt->sa), ssid_txt);
 259                 }
 260                 return;
 261         }
 262
 263         /* TODO: verify that supp_rates contains at least one matching rate
 264          * with AP configuration */
 265 #define MAX_PROBERESP_LEN 768
 266         resp = os_zalloc(MAX_PROBERESP_LEN);
 267         if (resp == NULL)
 268                 return;
 269         epos = ((u8 *) resp) + MAX_PROBERESP_LEN;
 270
 271         resp->frame_control = IEEE80211_FC(WLAN_FC_TYPE_MGMT,
 272                                            WLAN_FC_STYPE_PROBE_RESP);
 273         os_memcpy(resp->da, mgmt->sa, ETH_ALEN);
 274         os_memcpy(resp->sa, hapd->own_addr, ETH_ALEN);
 275
 276         os_memcpy(resp->bssid, hapd->own_addr, ETH_ALEN);
 277         resp->u.probe_resp.beacon_int =
 278                 host_to_le16(hapd->iconf->beacon_int);
 279
 280         /* hardware or low-level driver will setup seq_ctrl and timestamp */
 281         resp->u.probe_resp.capab_info =
 282                 host_to_le16(hostapd_own_capab_info(hapd, sta, 1));
 283
 284         pos = resp->u.probe_resp.variable;
 285         *pos++ = WLAN_EID_SSID;
 286         *pos++ = ssid_len;
 287         os_memcpy(pos, ssid, ssid_len);
 288         pos += ssid_len;
 289
 290         /* Supported rates */
 291         pos = hostapd_eid_supp_rates(hapd, pos);
 292
 293         /* DS Params */
 294         pos = hostapd_eid_ds_params(hapd, pos);
 295
 296         pos = hostapd_eid_country(hapd, pos, epos - pos);
 297
 298         /* ERP Information element */
 299         pos = hostapd_eid_erp_info(hapd, pos);
 300
 301         /* Extended supported rates */
 302         pos = hostapd_eid_ext_supp_rates(hapd, pos);
 303
 304         pos = hostapd_eid_wpa(hapd, pos, epos - pos, sta);
 305
 306         /* Wi-Fi Alliance WMM */
 307         pos = hostapd_eid_wmm(hapd, pos);
 308
 309 #ifdef CONFIG_IEEE80211N
 310         pos = hostapd_eid_ht_capabilities(hapd, pos);
 311         pos = hostapd_eid_ht_operation(hapd, pos);
 312 #endif /* CONFIG_IEEE80211N */
 313
 314 #ifdef CONFIG_WPS
 315         if (hapd->conf->wps_state && hapd->wps_probe_resp_ie) {
 316                 os_memcpy(pos, wpabuf_head(hapd->wps_probe_resp_ie),
 317                           wpabuf_len(hapd->wps_probe_resp_ie));
 318                 pos += wpabuf_len(hapd->wps_probe_resp_ie);
 319         }
 320 #endif /* CONFIG_WPS */
 321
 322         if (hapd->drv.send_mgmt_frame(hapd, resp, pos - (u8 *) resp) < 0)
 323                 perror("handle_probe_req: send");
 324
 325         os_free(resp);
 326
 327         wpa_printf(MSG_MSGDUMP, "STA " MACSTR " sent probe request for %s "
 328                    "SSID", MAC2STR(mgmt->sa),
 329                    elems.ssid_len == 0 ? "broadcast" : "our");
 330 }
 331
 332
 333 void ieee802_11_set_beacon(struct hostapd_data *hapd)
 334 {
 335         struct ieee80211_mgmt *head;
 336         u8 *pos, *tail, *tailpos;
 337         u16 capab_info;
 338         size_t head_len, tail_len;
 339
 340 #define BEACON_HEAD_BUF_SIZE 256
 341 #define BEACON_TAIL_BUF_SIZE 512
 342         head = os_zalloc(BEACON_HEAD_BUF_SIZE);
 343         tailpos = tail = os_malloc(BEACON_TAIL_BUF_SIZE);
 344         if (head == NULL || tail == NULL) {
 345                 wpa_printf(MSG_ERROR, "Failed to set beacon data");
 346                 os_free(head);
 347                 os_free(tail);
 348                 return;
 349         }
 350
 351         head->frame_control = IEEE80211_FC(WLAN_FC_TYPE_MGMT,
 352                                            WLAN_FC_STYPE_BEACON);
 353         head->duration = host_to_le16(0);
 354         os_memset(head->da, 0xff, ETH_ALEN);
 355
 356         os_memcpy(head->sa, hapd->own_addr, ETH_ALEN);
 357         os_memcpy(head->bssid, hapd->own_addr, ETH_ALEN);
 358         head->u.beacon.beacon_int =
 359                 host_to_le16(hapd->iconf->beacon_int);
 360
 361         /* hardware or low-level driver will setup seq_ctrl and timestamp */
 362         capab_info = hostapd_own_capab_info(hapd, NULL, 0);
 363         head->u.beacon.capab_info = host_to_le16(capab_info);
 364         pos = &head->u.beacon.variable[0];
 365
 366         /* SSID */
 367         *pos++ = WLAN_EID_SSID;
 368         if (hapd->conf->ignore_broadcast_ssid == 2) {
 369                 /* clear the data, but keep the correct length of the SSID */
 370                 *pos++ = hapd->conf->ssid.ssid_len;
 371                 os_memset(pos, 0, hapd->conf->ssid.ssid_len);
 372                 pos += hapd->conf->ssid.ssid_len;
 373         } else if (hapd->conf->ignore_broadcast_ssid) {
 374                 *pos++ = 0; /* empty SSID */
 375         } else {
 376                 *pos++ = hapd->conf->ssid.ssid_len;
 377                 os_memcpy(pos, hapd->conf->ssid.ssid,
 378                           hapd->conf->ssid.ssid_len);
 379                 pos += hapd->conf->ssid.ssid_len;
 380         }
 381
 382         /* Supported rates */
 383         pos = hostapd_eid_supp_rates(hapd, pos);
 384
 385         /* DS Params */
 386         pos = hostapd_eid_ds_params(hapd, pos);
 387
 388         head_len = pos - (u8 *) head;
 389
 390         tailpos = hostapd_eid_country(hapd, tailpos,
 391                                       tail + BEACON_TAIL_BUF_SIZE - tailpos);
 392
 393         /* ERP Information element */
 394         tailpos = hostapd_eid_erp_info(hapd, tailpos);
 395
 396         /* Extended supported rates */
 397         tailpos = hostapd_eid_ext_supp_rates(hapd, tailpos);
 398
 399         tailpos = hostapd_eid_wpa(hapd, tailpos, tail + BEACON_TAIL_BUF_SIZE -
 400                                   tailpos, NULL);
 401
 402         /* Wi-Fi Alliance WMM */
 403         tailpos = hostapd_eid_wmm(hapd, tailpos);
 404
 405 #ifdef CONFIG_IEEE80211N
 406         tailpos = hostapd_eid_ht_capabilities(hapd, tailpos);
 407         tailpos = hostapd_eid_ht_operation(hapd, tailpos);
 408 #endif /* CONFIG_IEEE80211N */
 409
 410 #ifdef CONFIG_WPS
 411         if (hapd->conf->wps_state && hapd->wps_beacon_ie) {
 412                 os_memcpy(tailpos, wpabuf_head(hapd->wps_beacon_ie),
 413                           wpabuf_len(hapd->wps_beacon_ie));
 414                 tailpos += wpabuf_len(hapd->wps_beacon_ie);
 415         }
 416 #endif /* CONFIG_WPS */
 417
 418         tail_len = tailpos > tail ? tailpos - tail : 0;
 419
 420         if (hapd->drv.set_beacon(hapd->conf->iface, hapd,
 421                                  (u8 *) head, head_len,
 422                                  tail, tail_len, hapd->conf->dtim_period,
 423                                  hapd->iconf->beacon_int))
 424                 wpa_printf(MSG_ERROR, "Failed to set beacon head/tail or DTIM "
 425                            "period");
 426
 427         os_free(tail);
 428         os_free(head);
 429
 430         hapd->drv.set_bss_params(hapd, !!(ieee802_11_erp_info(hapd) &
 431                                           ERP_INFO_USE_PROTECTION));
 432 }
 433
 434
 435 void ieee802_11_set_beacons(struct hostapd_iface *iface)
 436 {
 437         size_t i;
 438         for (i = 0; i < iface->num_bss; i++)
 439                 ieee802_11_set_beacon(iface->bss[i]);
 440 }
 441
 442 #endif /* CONFIG_NATIVE_WINDOWS */