hostapd/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, Jouni Malinen <j@w1.fi>
   6  * Copyright (c) 2007-2008, Intel Corporation
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License version 2 as
  10  * published by the Free Software Foundation.
  11  *
  12  * Alternatively, this software may be distributed under the terms of BSD
  13  * license.
  14  *
  15  * See README and COPYING for more details.
  16  */
  17
  18 #include "includes.h"
  19
  20 #ifndef CONFIG_NATIVE_WINDOWS
  21
  22 #include "hostapd.h"
  23 #include "ieee802_11.h"
  24 #include "wpa.h"
  25 #include "wme.h"
  26 #include "beacon.h"
  27 #include "hw_features.h"
  28 #include "driver.h"
  29 #include "sta_info.h"
  30 #include "ieee802_11h.h"
  31
  32
  33 static u8 ieee802_11_erp_info(struct hostapd_data *hapd)
  34 {
  35         u8 erp = 0;
  36
  37         if (hapd->iface->current_mode == NULL ||
  38             hapd->iface->current_mode->mode != HOSTAPD_MODE_IEEE80211G)
  39                 return 0;
  40
  41         switch (hapd->iconf->cts_protection_type) {
  42         case CTS_PROTECTION_FORCE_ENABLED:
  43                 erp |= ERP_INFO_NON_ERP_PRESENT | ERP_INFO_USE_PROTECTION;
  44                 break;
  45         case CTS_PROTECTION_FORCE_DISABLED:
  46                 erp = 0;
  47                 break;
  48         case CTS_PROTECTION_AUTOMATIC:
  49                 if (hapd->iface->olbc)
  50                         erp |= ERP_INFO_USE_PROTECTION;
  51                 /* continue */
  52         case CTS_PROTECTION_AUTOMATIC_NO_OLBC:
  53                 if (hapd->iface->num_sta_non_erp > 0) {
  54                         erp |= ERP_INFO_NON_ERP_PRESENT |
  55                                 ERP_INFO_USE_PROTECTION;
  56                 }
  57                 break;
  58         }
  59         if (hapd->iface->num_sta_no_short_preamble > 0)
  60                 erp |= ERP_INFO_BARKER_PREAMBLE_MODE;
  61
  62         return erp;
  63 }
  64
  65
  66 static u8 * hostapd_eid_ds_params(struct hostapd_data *hapd, u8 *eid)
  67 {
  68         *eid++ = WLAN_EID_DS_PARAMS;
  69         *eid++ = 1;
  70         *eid++ = hapd->iconf->channel;
  71         return eid;
  72 }
  73
  74
  75 static u8 * hostapd_eid_erp_info(struct hostapd_data *hapd, u8 *eid)
  76 {
  77         if (hapd->iface->current_mode == NULL ||
  78             hapd->iface->current_mode->mode != HOSTAPD_MODE_IEEE80211G)
  79                 return eid;
  80
  81         /* Set NonERP_present and use_protection bits if there
  82          * are any associated NonERP stations. */
  83         /* TODO: use_protection bit can be set to zero even if
  84          * there are NonERP stations present. This optimization
  85          * might be useful if NonERP stations are "quiet".
  86          * See 802.11g/D6 E-1 for recommended practice.
  87          * In addition, Non ERP present might be set, if AP detects Non ERP
  88          * operation on other APs. */
  89
  90         /* Add ERP Information element */
  91         *eid++ = WLAN_EID_ERP_INFO;
  92         *eid++ = 1;
  93         *eid++ = ieee802_11_erp_info(hapd);
  94
  95         return eid;
  96 }
  97
  98
  99 static u8 * hostapd_eid_country(struct hostapd_data *hapd, u8 *eid,
 100                                 int max_len)
 101 {
 102         u8 *pos = eid;
 103
 104         if ((!hapd->iconf->ieee80211d && !hapd->iface->dfs_enable) ||
 105             max_len < 6)
 106                 return eid;
 107
 108         *pos++ = WLAN_EID_COUNTRY;
 109         pos++; /* length will be set later */
 110         os_memcpy(pos, hapd->iconf->country, 3); /* e.g., 'US ' */
 111         pos += 3;
 112
 113         if ((pos - eid) & 1)
 114                 *pos++ = 0; /* pad for 16-bit alignment */
 115
 116         eid[1] = (pos - eid) - 2;
 117
 118         return pos;
 119 }
 120
 121
 122 static u8 * hostapd_eid_power_constraint(struct hostapd_data *hapd, u8 *eid)
 123
 124 {
 125         if (!hapd->iface->dfs_enable)
 126                 return eid;
 127         *eid++ = WLAN_EID_PWR_CONSTRAINT;
 128         *eid++ = 1;
 129         *eid++ = hapd->iface->pwr_const;
 130         return eid;
 131 }
 132
 133
 134 static u8 * hostapd_eid_tpc_report(struct hostapd_data *hapd, u8 *eid)
 135
 136 {
 137         if (!hapd->iface->dfs_enable)
 138                 return eid;
 139         *eid++ = WLAN_EID_TPC_REPORT;
 140         *eid++ = 2;
 141         *eid++ = hapd->iface->tx_power; /* TX POWER */
 142         *eid++ = 0; /* Link Margin */
 143         return eid;
 144 }
 145
 146 static u8 * hostapd_eid_channel_switch(struct hostapd_data *hapd, u8 *eid)
 147
 148 {
 149         if (!hapd->iface->dfs_enable || !hapd->iface->channel_switch)
 150                 return eid;
 151         *eid++ = WLAN_EID_CHANNEL_SWITCH;
 152         *eid++ = 3;
 153         *eid++ = CHAN_SWITCH_MODE_QUIET;
 154         *eid++ = hapd->iface->channel_switch; /* New channel */
 155         /* 0 - very soon; 1 - before next TBTT; num - after num beacons */
 156         *eid++ = 0;
 157         return eid;
 158 }
 159
 160
 161 static u8 * hostapd_eid_wpa(struct hostapd_data *hapd, u8 *eid, size_t len,
 162                             struct sta_info *sta)
 163 {
 164         const u8 *ie;
 165         size_t ielen;
 166
 167         ie = wpa_auth_get_wpa_ie(hapd->wpa_auth, &ielen);
 168         if (ie == NULL || ielen > len)
 169                 return eid;
 170
 171         os_memcpy(eid, ie, ielen);
 172         return eid + ielen;
 173 }
 174
 175
 176 void handle_probe_req(struct hostapd_data *hapd, struct ieee80211_mgmt *mgmt,
 177                       size_t len)
 178 {
 179         struct ieee80211_mgmt *resp;
 180         struct ieee802_11_elems elems;
 181         char *ssid;
 182         u8 *pos, *epos, *ie;
 183         size_t ssid_len, ie_len;
 184         struct sta_info *sta = NULL;
 185
 186         ie = mgmt->u.probe_req.variable;
 187         ie_len = len - (IEEE80211_HDRLEN + sizeof(mgmt->u.probe_req));
 188
 189         if (!hapd->iconf->send_probe_response)
 190                 return;
 191
 192         if (ieee802_11_parse_elems(hapd, ie, ie_len, &elems, 0) == ParseFailed)
 193         {
 194                 wpa_printf(MSG_DEBUG, "Could not parse ProbeReq from " MACSTR,
 195                            MAC2STR(mgmt->sa));
 196                 return;
 197         }
 198
 199         ssid = NULL;
 200         ssid_len = 0;
 201
 202         if ((!elems.ssid || !elems.supp_rates)) {
 203                 wpa_printf(MSG_DEBUG, "STA " MACSTR " sent probe request "
 204                            "without SSID or supported rates element",
 205                            MAC2STR(mgmt->sa));
 206                 return;
 207         }
 208
 209         if (hapd->conf->ignore_broadcast_ssid && elems.ssid_len == 0) {
 210                 wpa_printf(MSG_MSGDUMP, "Probe Request from " MACSTR " for "
 211                            "broadcast SSID ignored", MAC2STR(mgmt->sa));
 212                 return;
 213         }
 214
 215         sta = ap_get_sta(hapd, mgmt->sa);
 216
 217         if (elems.ssid_len == 0 ||
 218             (elems.ssid_len == hapd->conf->ssid.ssid_len &&
 219              os_memcmp(elems.ssid, hapd->conf->ssid.ssid, elems.ssid_len) ==
 220              0)) {
 221                 ssid = hapd->conf->ssid.ssid;
 222                 ssid_len = hapd->conf->ssid.ssid_len;
 223                 if (sta)
 224                         sta->ssid_probe = &hapd->conf->ssid;
 225         }
 226
 227         if (!ssid) {
 228                 if (!(mgmt->da[0] & 0x01)) {
 229                         char ssid_txt[33];
 230                         ieee802_11_print_ssid(ssid_txt, elems.ssid,
 231                                               elems.ssid_len);
 232                         wpa_printf(MSG_MSGDUMP, "Probe Request from " MACSTR
 233                                    " for foreign SSID '%s'",
 234                                    MAC2STR(mgmt->sa), ssid_txt);
 235                 }
 236                 return;
 237         }
 238
 239         /* TODO: verify that supp_rates contains at least one matching rate
 240          * with AP configuration */
 241 #define MAX_PROBERESP_LEN 768
 242         resp = os_zalloc(MAX_PROBERESP_LEN);
 243         if (resp == NULL)
 244                 return;
 245         epos = ((u8 *) resp) + MAX_PROBERESP_LEN;
 246
 247         resp->frame_control = IEEE80211_FC(WLAN_FC_TYPE_MGMT,
 248                                            WLAN_FC_STYPE_PROBE_RESP);
 249         os_memcpy(resp->da, mgmt->sa, ETH_ALEN);
 250         os_memcpy(resp->sa, hapd->own_addr, ETH_ALEN);
 251
 252         os_memcpy(resp->bssid, hapd->own_addr, ETH_ALEN);
 253         resp->u.probe_resp.beacon_int =
 254                 host_to_le16(hapd->iconf->beacon_int);
 255
 256         /* hardware or low-level driver will setup seq_ctrl and timestamp */
 257         resp->u.probe_resp.capab_info =
 258                 host_to_le16(hostapd_own_capab_info(hapd, sta, 1));
 259
 260         pos = resp->u.probe_resp.variable;
 261         *pos++ = WLAN_EID_SSID;
 262         *pos++ = ssid_len;
 263         os_memcpy(pos, ssid, ssid_len);
 264         pos += ssid_len;
 265
 266         /* Supported rates */
 267         pos = hostapd_eid_supp_rates(hapd, pos);
 268
 269         /* DS Params */
 270         pos = hostapd_eid_ds_params(hapd, pos);
 271
 272         pos = hostapd_eid_country(hapd, pos, epos - pos);
 273
 274         pos = hostapd_eid_power_constraint(hapd, pos);
 275         pos = hostapd_eid_tpc_report(hapd, pos);
 276
 277         /* ERP Information element */
 278         pos = hostapd_eid_erp_info(hapd, pos);
 279
 280         /* Extended supported rates */
 281         pos = hostapd_eid_ext_supp_rates(hapd, pos);
 282
 283         pos = hostapd_eid_wpa(hapd, pos, epos - pos, sta);
 284
 285         /* Wi-Fi Wireless Multimedia Extensions */
 286         if (hapd->conf->wme_enabled)
 287                 pos = hostapd_eid_wme(hapd, pos);
 288
 289 #ifdef CONFIG_IEEE80211N
 290         if (hapd->conf->ieee80211n) {
 291                 pos = hostapd_eid_ht_capabilities_info(hapd, pos);
 292                 pos = hostapd_eid_ht_operation(hapd, pos);
 293         }
 294 #endif /* CONFIG_IEEE80211N */
 295
 296         if (hostapd_send_mgmt_frame(hapd, resp, pos - (u8 *) resp, 0) < 0)
 297                 perror("handle_probe_req: send");
 298
 299         os_free(resp);
 300
 301         wpa_printf(MSG_MSGDUMP, "STA " MACSTR " sent probe request for %s "
 302                    "SSID", MAC2STR(mgmt->sa),
 303                    elems.ssid_len == 0 ? "broadcast" : "our");
 304 }
 305
 306
 307 void ieee802_11_set_beacon(struct hostapd_data *hapd)
 308 {
 309         struct ieee80211_mgmt *head;
 310         u8 *pos, *tail, *tailpos;
 311         int preamble;
 312         u16 capab_info;
 313         size_t head_len, tail_len;
 314         int cts_protection = ((ieee802_11_erp_info(hapd) &
 315                               ERP_INFO_USE_PROTECTION) ? 1 : 0);
 316
 317 #define BEACON_HEAD_BUF_SIZE 256
 318 #define BEACON_TAIL_BUF_SIZE 512
 319         head = os_zalloc(BEACON_HEAD_BUF_SIZE);
 320         tailpos = tail = os_malloc(BEACON_TAIL_BUF_SIZE);
 321         if (head == NULL || tail == NULL) {
 322                 wpa_printf(MSG_ERROR, "Failed to set beacon data");
 323                 os_free(head);
 324                 os_free(tail);
 325                 return;
 326         }
 327
 328         head->frame_control = IEEE80211_FC(WLAN_FC_TYPE_MGMT,
 329                                            WLAN_FC_STYPE_BEACON);
 330         head->duration = host_to_le16(0);
 331         os_memset(head->da, 0xff, ETH_ALEN);
 332
 333         os_memcpy(head->sa, hapd->own_addr, ETH_ALEN);
 334         os_memcpy(head->bssid, hapd->own_addr, ETH_ALEN);
 335         head->u.beacon.beacon_int =
 336                 host_to_le16(hapd->iconf->beacon_int);
 337
 338         /* hardware or low-level driver will setup seq_ctrl and timestamp */
 339         capab_info = hostapd_own_capab_info(hapd, NULL, 0);
 340         head->u.beacon.capab_info = host_to_le16(capab_info);
 341         pos = &head->u.beacon.variable[0];
 342
 343         /* SSID */
 344         *pos++ = WLAN_EID_SSID;
 345         if (hapd->conf->ignore_broadcast_ssid == 2) {
 346                 /* clear the data, but keep the correct length of the SSID */
 347                 *pos++ = hapd->conf->ssid.ssid_len;
 348                 os_memset(pos, 0, hapd->conf->ssid.ssid_len);
 349                 pos += hapd->conf->ssid.ssid_len;
 350         } else if (hapd->conf->ignore_broadcast_ssid) {
 351                 *pos++ = 0; /* empty SSID */
 352         } else {
 353                 *pos++ = hapd->conf->ssid.ssid_len;
 354                 os_memcpy(pos, hapd->conf->ssid.ssid,
 355                           hapd->conf->ssid.ssid_len);
 356                 pos += hapd->conf->ssid.ssid_len;
 357         }
 358
 359         /* Supported rates */
 360         pos = hostapd_eid_supp_rates(hapd, pos);
 361
 362         /* DS Params */
 363         pos = hostapd_eid_ds_params(hapd, pos);
 364
 365         head_len = pos - (u8 *) head;
 366
 367         tailpos = hostapd_eid_country(hapd, tailpos,
 368                                       tail + BEACON_TAIL_BUF_SIZE - tailpos);
 369
 370         tailpos = hostapd_eid_power_constraint(hapd, tailpos);
 371         tailpos = hostapd_eid_channel_switch(hapd, tailpos);
 372         tailpos = hostapd_eid_tpc_report(hapd, tailpos);
 373
 374         /* ERP Information element */
 375         tailpos = hostapd_eid_erp_info(hapd, tailpos);
 376
 377         /* Extended supported rates */
 378         tailpos = hostapd_eid_ext_supp_rates(hapd, tailpos);
 379
 380         tailpos = hostapd_eid_wpa(hapd, tailpos, tail + BEACON_TAIL_BUF_SIZE -
 381                                   tailpos, NULL);
 382
 383         /* Wi-Fi Wireless Multimedia Extensions */
 384         if (hapd->conf->wme_enabled)
 385                 tailpos = hostapd_eid_wme(hapd, tailpos);
 386
 387 #ifdef CONFIG_IEEE80211N
 388         if (hapd->conf->ieee80211n) {
 389                 tailpos = hostapd_eid_ht_capabilities_info(hapd, tailpos);
 390                 tailpos = hostapd_eid_ht_operation(hapd, tailpos);
 391
 392                 if (hostapd_set_ht_capability(
 393                             hapd->conf->iface, hapd,
 394                             &hapd->conf->ht_capabilities.data)) {
 395                         wpa_printf(MSG_ERROR, "Could not set HT capabilities "
 396                                    "for kernel driver");
 397                 }
 398                 if (hostapd_set_ht_operation(
 399                             hapd->conf->iface, hapd,
 400                             &hapd->conf->ht_operation.data))
 401                         wpa_printf(MSG_ERROR, "Could not set HT operation for "
 402                                    "kernel driver");
 403         }
 404 #endif /* CONFIG_IEEE80211N */
 405
 406         tail_len = tailpos > tail ? tailpos - tail : 0;
 407
 408         if (hostapd_set_beacon(hapd->conf->iface, hapd, (u8 *) head, head_len,
 409                                tail, tail_len))
 410                 wpa_printf(MSG_ERROR, "Failed to set beacon head/tail");
 411
 412         os_free(tail);
 413         os_free(head);
 414
 415         if (hostapd_set_cts_protect(hapd, cts_protection))
 416                 wpa_printf(MSG_ERROR, "Failed to set CTS protect in kernel "
 417                            "driver");
 418
 419         if (hapd->iface->current_mode &&
 420             hapd->iface->current_mode->mode == HOSTAPD_MODE_IEEE80211G &&
 421             hostapd_set_short_slot_time(hapd,
 422                                         hapd->iface->num_sta_no_short_slot_time
 423                                         > 0 ? 0 : 1))
 424                 wpa_printf(MSG_ERROR, "Failed to set Short Slot Time option "
 425                            "in kernel driver");
 426
 427         if (hapd->iface->num_sta_no_short_preamble == 0 &&
 428             hapd->iconf->preamble == SHORT_PREAMBLE)
 429                 preamble = SHORT_PREAMBLE;
 430         else
 431                 preamble = LONG_PREAMBLE;
 432         if (hostapd_set_preamble(hapd, preamble))
 433                 wpa_printf(MSG_ERROR, "Could not set preamble for kernel "
 434                            "driver");
 435 }
 436
 437
 438 void ieee802_11_set_beacons(struct hostapd_iface *iface)
 439 {
 440         size_t i;
 441         for (i = 0; i < iface->num_bss; i++)
 442                 ieee802_11_set_beacon(iface->bss[i]);
 443 }
 444
 445 #endif /* CONFIG_NATIVE_WINDOWS */