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