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) 2008-2009, 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 "wme.h"
  26 #include "beacon.h"
  27 #include "hw_features.h"
  28 #include "driver_i.h"
  29 #include "sta_info.h"
  30 #include "wps_hostapd.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_add(u8 *pos, u8 *end, int chan_spacing,
 100                                     struct hostapd_channel_data *start,
 101                                     struct hostapd_channel_data *prev)
 102 {
 103         if (end - pos < 3)
 104                 return pos;
 105
 106         /* first channel number */
 107         *pos++ = start->chan;
 108         /* number of channels */
 109         *pos++ = (prev->chan - start->chan) / chan_spacing + 1;
 110         /* maximum transmit power level */
 111         *pos++ = start->max_tx_power;
 112
 113         return pos;
 114 }
 115
 116
 117 static u8 * hostapd_eid_country(struct hostapd_data *hapd, u8 *eid,
 118                                 int max_len)
 119 {
 120         u8 *pos = eid;
 121         u8 *end = eid + max_len;
 122         int i;
 123         struct hostapd_hw_modes *mode;
 124         struct hostapd_channel_data *start, *prev;
 125         int chan_spacing = 1;
 126
 127         if (!hapd->iconf->ieee80211d || max_len < 6 ||
 128             hapd->iface->current_mode == NULL)
 129                 return eid;
 130
 131         *pos++ = WLAN_EID_COUNTRY;
 132         pos++; /* length will be set later */
 133         os_memcpy(pos, hapd->iconf->country, 3); /* e.g., 'US ' */
 134         pos += 3;
 135
 136         mode = hapd->iface->current_mode;
 137         if (mode->mode == HOSTAPD_MODE_IEEE80211A)
 138                 chan_spacing = 4;
 139
 140         start = prev = NULL;
 141         for (i = 0; i < mode->num_channels; i++) {
 142                 struct hostapd_channel_data *chan = &mode->channels[i];
 143                 if (chan->flag & HOSTAPD_CHAN_DISABLED)
 144                         continue;
 145                 if (start && prev &&
 146                     prev->chan + chan_spacing == chan->chan &&
 147                     start->max_tx_power == chan->max_tx_power) {
 148                         prev = chan;
 149                         continue; /* can use same entry */
 150                 }
 151
 152                 if (start) {
 153                         pos = hostapd_eid_country_add(pos, end, chan_spacing,
 154                                                       start, prev);
 155                         start = NULL;
 156                 }
 157
 158                 /* Start new group */
 159                 start = prev = chan;
 160         }
 161
 162         if (start) {
 163                 pos = hostapd_eid_country_add(pos, end, chan_spacing,
 164                                               start, prev);
 165         }
 166
 167         if ((pos - eid) & 1) {
 168                 if (end - pos < 1)
 169                         return eid;
 170                 *pos++ = 0; /* pad for 16-bit alignment */
 171         }
 172
 173         eid[1] = (pos - eid) - 2;
 174
 175         return pos;
 176 }
 177
 178
 179 static u8 * hostapd_eid_wpa(struct hostapd_data *hapd, u8 *eid, size_t len,
 180                             struct sta_info *sta)
 181 {
 182         const u8 *ie;
 183         size_t ielen;
 184
 185         ie = wpa_auth_get_wpa_ie(hapd->wpa_auth, &ielen);
 186         if (ie == NULL || ielen > len)
 187                 return eid;
 188
 189         os_memcpy(eid, ie, ielen);
 190         return eid + ielen;
 191 }
 192
 193
 194 void handle_probe_req(struct hostapd_data *hapd,
 195                       const struct ieee80211_mgmt *mgmt, size_t len)
 196 {
 197         struct ieee80211_mgmt *resp;
 198         struct ieee802_11_elems elems;
 199         char *ssid;
 200         u8 *pos, *epos;
 201         const u8 *ie;
 202         size_t ssid_len, ie_len;
 203         struct sta_info *sta = NULL;
 204
 205         ie = mgmt->u.probe_req.variable;
 206         ie_len = len - (IEEE80211_HDRLEN + sizeof(mgmt->u.probe_req));
 207
 208         hostapd_probe_req_rx(hapd, mgmt->sa, ie, ie_len);
 209
 210         if (!hapd->iconf->send_probe_response)
 211                 return;
 212
 213         if (ieee802_11_parse_elems(ie, ie_len, &elems, 0) == ParseFailed) {
 214                 wpa_printf(MSG_DEBUG, "Could not parse ProbeReq from " MACSTR,
 215                            MAC2STR(mgmt->sa));
 216                 return;
 217         }
 218
 219         ssid = NULL;
 220         ssid_len = 0;
 221
 222         if ((!elems.ssid || !elems.supp_rates)) {
 223                 wpa_printf(MSG_DEBUG, "STA " MACSTR " sent probe request "
 224                            "without SSID or supported rates element",
 225                            MAC2STR(mgmt->sa));
 226                 return;
 227         }
 228
 229         if (hapd->conf->ignore_broadcast_ssid && elems.ssid_len == 0) {
 230                 wpa_printf(MSG_MSGDUMP, "Probe Request from " MACSTR " for "
 231                            "broadcast SSID ignored", MAC2STR(mgmt->sa));
 232                 return;
 233         }
 234
 235         sta = ap_get_sta(hapd, mgmt->sa);
 236
 237         if (elems.ssid_len == 0 ||
 238             (elems.ssid_len == hapd->conf->ssid.ssid_len &&
 239              os_memcmp(elems.ssid, hapd->conf->ssid.ssid, elems.ssid_len) ==
 240              0)) {
 241                 ssid = hapd->conf->ssid.ssid;
 242                 ssid_len = hapd->conf->ssid.ssid_len;
 243                 if (sta)
 244                         sta->ssid_probe = &hapd->conf->ssid;
 245         }
 246
 247         if (!ssid) {
 248                 if (!(mgmt->da[0] & 0x01)) {
 249                         char ssid_txt[33];
 250                         ieee802_11_print_ssid(ssid_txt, elems.ssid,
 251                                               elems.ssid_len);
 252                         wpa_printf(MSG_MSGDUMP, "Probe Request from " MACSTR
 253                                    " for foreign SSID '%s'",
 254                                    MAC2STR(mgmt->sa), ssid_txt);
 255                 }
 256                 return;
 257         }
 258
 259         /* TODO: verify that supp_rates contains at least one matching rate
 260          * with AP configuration */
 261 #define MAX_PROBERESP_LEN 768
 262         resp = os_zalloc(MAX_PROBERESP_LEN);
 263         if (resp == NULL)
 264                 return;
 265         epos = ((u8 *) resp) + MAX_PROBERESP_LEN;
 266
 267         resp->frame_control = IEEE80211_FC(WLAN_FC_TYPE_MGMT,
 268                                            WLAN_FC_STYPE_PROBE_RESP);
 269         os_memcpy(resp->da, mgmt->sa, ETH_ALEN);
 270         os_memcpy(resp->sa, hapd->own_addr, ETH_ALEN);
 271
 272         os_memcpy(resp->bssid, hapd->own_addr, ETH_ALEN);
 273         resp->u.probe_resp.beacon_int =
 274                 host_to_le16(hapd->iconf->beacon_int);
 275
 276         /* hardware or low-level driver will setup seq_ctrl and timestamp */
 277         resp->u.probe_resp.capab_info =
 278                 host_to_le16(hostapd_own_capab_info(hapd, sta, 1));
 279
 280         pos = resp->u.probe_resp.variable;
 281         *pos++ = WLAN_EID_SSID;
 282         *pos++ = ssid_len;
 283         os_memcpy(pos, ssid, ssid_len);
 284         pos += ssid_len;
 285
 286         /* Supported rates */
 287         pos = hostapd_eid_supp_rates(hapd, pos);
 288
 289         /* DS Params */
 290         pos = hostapd_eid_ds_params(hapd, pos);
 291
 292         pos = hostapd_eid_country(hapd, pos, epos - pos);
 293
 294         /* ERP Information element */
 295         pos = hostapd_eid_erp_info(hapd, pos);
 296
 297         /* Extended supported rates */
 298         pos = hostapd_eid_ext_supp_rates(hapd, pos);
 299
 300         pos = hostapd_eid_wpa(hapd, pos, epos - pos, sta);
 301
 302         /* Wi-Fi Alliance WMM */
 303         pos = hostapd_eid_wmm(hapd, pos);
 304
 305 #ifdef CONFIG_IEEE80211N
 306         pos = hostapd_eid_ht_capabilities(hapd, pos);
 307         pos = hostapd_eid_ht_operation(hapd, pos);
 308 #endif /* CONFIG_IEEE80211N */
 309
 310 #ifdef CONFIG_WPS
 311         if (hapd->conf->wps_state && hapd->wps_probe_resp_ie) {
 312                 os_memcpy(pos, hapd->wps_probe_resp_ie,
 313                           hapd->wps_probe_resp_ie_len);
 314                 pos += hapd->wps_probe_resp_ie_len;
 315         }
 316 #endif /* CONFIG_WPS */
 317
 318         if (hostapd_send_mgmt_frame(hapd, resp, pos - (u8 *) resp) < 0)
 319                 perror("handle_probe_req: send");
 320
 321         os_free(resp);
 322
 323         wpa_printf(MSG_MSGDUMP, "STA " MACSTR " sent probe request for %s "
 324                    "SSID", MAC2STR(mgmt->sa),
 325                    elems.ssid_len == 0 ? "broadcast" : "our");
 326 }
 327
 328
 329 void ieee802_11_set_beacon(struct hostapd_data *hapd)
 330 {
 331         struct ieee80211_mgmt *head;
 332         u8 *pos, *tail, *tailpos;
 333         int preamble;
 334         u16 capab_info;
 335         size_t head_len, tail_len;
 336         int cts_protection = ((ieee802_11_erp_info(hapd) &
 337                               ERP_INFO_USE_PROTECTION) ? 1 : 0);
 338
 339 #define BEACON_HEAD_BUF_SIZE 256
 340 #define BEACON_TAIL_BUF_SIZE 512
 341         head = os_zalloc(BEACON_HEAD_BUF_SIZE);
 342         tailpos = tail = os_malloc(BEACON_TAIL_BUF_SIZE);
 343         if (head == NULL || tail == NULL) {
 344                 wpa_printf(MSG_ERROR, "Failed to set beacon data");
 345                 os_free(head);
 346                 os_free(tail);
 347                 return;
 348         }
 349
 350         head->frame_control = IEEE80211_FC(WLAN_FC_TYPE_MGMT,
 351                                            WLAN_FC_STYPE_BEACON);
 352         head->duration = host_to_le16(0);
 353         os_memset(head->da, 0xff, ETH_ALEN);
 354
 355         os_memcpy(head->sa, hapd->own_addr, ETH_ALEN);
 356         os_memcpy(head->bssid, hapd->own_addr, ETH_ALEN);
 357         head->u.beacon.beacon_int =
 358                 host_to_le16(hapd->iconf->beacon_int);
 359
 360         /* hardware or low-level driver will setup seq_ctrl and timestamp */
 361         capab_info = hostapd_own_capab_info(hapd, NULL, 0);
 362         head->u.beacon.capab_info = host_to_le16(capab_info);
 363         pos = &head->u.beacon.variable[0];
 364
 365         /* SSID */
 366         *pos++ = WLAN_EID_SSID;
 367         if (hapd->conf->ignore_broadcast_ssid == 2) {
 368                 /* clear the data, but keep the correct length of the SSID */
 369                 *pos++ = hapd->conf->ssid.ssid_len;
 370                 os_memset(pos, 0, hapd->conf->ssid.ssid_len);
 371                 pos += hapd->conf->ssid.ssid_len;
 372         } else if (hapd->conf->ignore_broadcast_ssid) {
 373                 *pos++ = 0; /* empty SSID */
 374         } else {
 375                 *pos++ = hapd->conf->ssid.ssid_len;
 376                 os_memcpy(pos, hapd->conf->ssid.ssid,
 377                           hapd->conf->ssid.ssid_len);
 378                 pos += hapd->conf->ssid.ssid_len;
 379         }
 380
 381         /* Supported rates */
 382         pos = hostapd_eid_supp_rates(hapd, pos);
 383
 384         /* DS Params */
 385         pos = hostapd_eid_ds_params(hapd, pos);
 386
 387         head_len = pos - (u8 *) head;
 388
 389         tailpos = hostapd_eid_country(hapd, tailpos,
 390                                       tail + BEACON_TAIL_BUF_SIZE - tailpos);
 391
 392         /* ERP Information element */
 393         tailpos = hostapd_eid_erp_info(hapd, tailpos);
 394
 395         /* Extended supported rates */
 396         tailpos = hostapd_eid_ext_supp_rates(hapd, tailpos);
 397
 398         tailpos = hostapd_eid_wpa(hapd, tailpos, tail + BEACON_TAIL_BUF_SIZE -
 399                                   tailpos, NULL);
 400
 401         /* Wi-Fi Alliance WMM */
 402         tailpos = hostapd_eid_wmm(hapd, tailpos);
 403
 404 #ifdef CONFIG_IEEE80211N
 405         if (hapd->iconf->ieee80211n) {
 406                 u8 *ht_capab, *ht_oper;
 407                 ht_capab = tailpos;
 408                 tailpos = hostapd_eid_ht_capabilities(hapd, tailpos);
 409
 410                 ht_oper = tailpos;
 411                 tailpos = hostapd_eid_ht_operation(hapd, tailpos);
 412
 413                 if (tailpos > ht_oper && ht_oper > ht_capab &&
 414                     hostapd_set_ht_params(hapd->conf->iface, hapd,
 415                                           ht_capab + 2, ht_capab[1],
 416                                           ht_oper + 2, ht_oper[1])) {
 417                         wpa_printf(MSG_ERROR, "Could not set HT capabilities "
 418                                    "for kernel driver");
 419                 }
 420         }
 421 #endif /* CONFIG_IEEE80211N */
 422
 423 #ifdef CONFIG_WPS
 424         if (hapd->conf->wps_state && hapd->wps_beacon_ie) {
 425                 os_memcpy(tailpos, hapd->wps_beacon_ie,
 426                           hapd->wps_beacon_ie_len);
 427                 tailpos += hapd->wps_beacon_ie_len;
 428         }
 429 #endif /* CONFIG_WPS */
 430
 431         tail_len = tailpos > tail ? tailpos - tail : 0;
 432
 433         if (hostapd_set_beacon(hapd->conf->iface, hapd, (u8 *) head, head_len,
 434                                tail, tail_len, hapd->conf->dtim_period,
 435                                hapd->iconf->beacon_int))
 436                 wpa_printf(MSG_ERROR, "Failed to set beacon head/tail or DTIM "
 437                            "period");
 438
 439         os_free(tail);
 440         os_free(head);
 441
 442         if (hostapd_set_cts_protect(hapd, cts_protection))
 443                 wpa_printf(MSG_ERROR, "Failed to set CTS protect in kernel "
 444                            "driver");
 445
 446         if (hapd->iface->current_mode &&
 447             hapd->iface->current_mode->mode == HOSTAPD_MODE_IEEE80211G &&
 448             hostapd_set_short_slot_time(hapd,
 449                                         hapd->iface->num_sta_no_short_slot_time
 450                                         > 0 ? 0 : 1))
 451                 wpa_printf(MSG_ERROR, "Failed to set Short Slot Time option "
 452                            "in kernel driver");
 453
 454         if (hapd->iface->num_sta_no_short_preamble == 0 &&
 455             hapd->iconf->preamble == SHORT_PREAMBLE)
 456                 preamble = SHORT_PREAMBLE;
 457         else
 458                 preamble = LONG_PREAMBLE;
 459         if (hostapd_set_preamble(hapd, preamble))
 460                 wpa_printf(MSG_ERROR, "Could not set preamble for kernel "
 461                            "driver");
 462 }
 463
 464
 465 void ieee802_11_set_beacons(struct hostapd_iface *iface)
 466 {
 467         size_t i;
 468         for (i = 0; i < iface->num_bss; i++)
 469                 ieee802_11_set_beacon(iface->bss[i]);
 470 }
 471
 472 #endif /* CONFIG_NATIVE_WINDOWS */