dist/wpa/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  *
   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 "hostapd.h"
  22 #include "ieee802_11.h"
  23 #include "wpa.h"
  24 #include "wme.h"
  25 #include "beacon.h"
  26 #include "hw_features.h"
  27 #include "driver.h"
  28 #include "sta_info.h"
  29 #include "ieee802_11h.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(struct hostapd_data *hapd, u8 *eid,
  99                                 int max_len)
 100 {
 101         u8 *pos = eid;
 102
 103         if ((!hapd->iconf->ieee80211d && !hapd->iface->dfs_enable) ||
 104             max_len < 6)
 105                 return eid;
 106
 107         *pos++ = WLAN_EID_COUNTRY;
 108         pos++; /* length will be set later */
 109         os_memcpy(pos, hapd->iconf->country, 3); /* e.g., 'US ' */
 110         pos += 3;
 111
 112         if ((pos - eid) & 1)
 113                 *pos++ = 0; /* pad for 16-bit alignment */
 114
 115         eid[1] = (pos - eid) - 2;
 116
 117         return pos;
 118 }
 119
 120
 121 static u8 * hostapd_eid_power_constraint(struct hostapd_data *hapd, u8 *eid)
 122
 123 {
 124         if (!hapd->iface->dfs_enable)
 125                 return eid;
 126         *eid++ = WLAN_EID_PWR_CONSTRAINT;
 127         *eid++ = 1;
 128         *eid++ = hapd->iface->pwr_const;
 129         return eid;
 130 }
 131
 132
 133 static u8 * hostapd_eid_tpc_report(struct hostapd_data *hapd, u8 *eid)
 134
 135 {
 136         if (!hapd->iface->dfs_enable)
 137                 return eid;
 138         *eid++ = WLAN_EID_TPC_REPORT;
 139         *eid++ = 2;
 140         *eid++ = hapd->iface->tx_power; /* TX POWER */
 141         *eid++ = 0; /* Link Margin */
 142         return eid;
 143 }
 144
 145 static u8 * hostapd_eid_channel_switch(struct hostapd_data *hapd, u8 *eid)
 146
 147 {
 148         if (!hapd->iface->dfs_enable || !hapd->iface->channel_switch)
 149                 return eid;
 150         *eid++ = WLAN_EID_CHANNEL_SWITCH;
 151         *eid++ = 3;
 152         *eid++ = CHAN_SWITCH_MODE_QUIET;
 153         *eid++ = hapd->iface->channel_switch; /* New channel */
 154         /* 0 - very soon; 1 - before next TBTT; num - after num beacons */
 155         *eid++ = 0;
 156         return eid;
 157 }
 158
 159
 160 static u8 * hostapd_eid_wpa(struct hostapd_data *hapd, u8 *eid, size_t len,
 161                             struct sta_info *sta)
 162 {
 163         const u8 *ie;
 164         size_t ielen;
 165
 166         ie = wpa_auth_get_wpa_ie(hapd->wpa_auth, &ielen);
 167         if (ie == NULL || ielen > len)
 168                 return eid;
 169
 170         os_memcpy(eid, ie, ielen);
 171         return eid + ielen;
 172 }
 173
 174
 175 void handle_probe_req(struct hostapd_data *hapd, struct ieee80211_mgmt *mgmt,
 176                       size_t len)
 177 {
 178         struct ieee80211_mgmt *resp;
 179         struct ieee802_11_elems elems;
 180         char *ssid;
 181         u8 *pos, *epos, *ie;
 182         size_t ssid_len, ie_len;
 183         struct sta_info *sta = NULL;
 184
 185         ie = mgmt->u.probe_req.variable;
 186         ie_len = len - (IEEE80211_HDRLEN + sizeof(mgmt->u.probe_req));
 187
 188         if (!hapd->iconf->send_probe_response)
 189                 return;
 190
 191         if (ieee802_11_parse_elems(hapd, ie, ie_len, &elems, 0) == ParseFailed)
 192         {
 193                 wpa_printf(MSG_DEBUG, "Could not parse ProbeReq from " MACSTR,
 194                            MAC2STR(mgmt->sa));
 195                 return;
 196         }
 197
 198         ssid = NULL;
 199         ssid_len = 0;
 200
 201         if ((!elems.ssid || !elems.supp_rates)) {
 202                 wpa_printf(MSG_DEBUG, "STA " MACSTR " sent probe request "
 203                            "without SSID or supported rates element",
 204                            MAC2STR(mgmt->sa));
 205                 return;
 206         }
 207
 208         if (hapd->conf->ignore_broadcast_ssid && elems.ssid_len == 0) {
 209                 wpa_printf(MSG_MSGDUMP, "Probe Request from " MACSTR " for "
 210                            "broadcast SSID ignored", MAC2STR(mgmt->sa));
 211                 return;
 212         }
 213
 214         sta = ap_get_sta(hapd, mgmt->sa);
 215
 216         if (elems.ssid_len == 0 ||
 217             (elems.ssid_len == hapd->conf->ssid.ssid_len &&
 218              os_memcmp(elems.ssid, hapd->conf->ssid.ssid, elems.ssid_len) ==
 219              0)) {
 220                 ssid = hapd->conf->ssid.ssid;
 221                 ssid_len = hapd->conf->ssid.ssid_len;
 222                 if (sta)
 223                         sta->ssid_probe = &hapd->conf->ssid;
 224         }
 225
 226         if (!ssid) {
 227                 if (!(mgmt->da[0] & 0x01)) {
 228                         char ssid_txt[33];
 229                         ieee802_11_print_ssid(ssid_txt, elems.ssid,
 230                                               elems.ssid_len);
 231                         wpa_printf(MSG_MSGDUMP, "Probe Request from " MACSTR
 232                                    " for foreign SSID '%s'",
 233                                    MAC2STR(mgmt->sa), ssid_txt);
 234                 }
 235                 return;
 236         }
 237
 238         /* TODO: verify that supp_rates contains at least one matching rate
 239          * with AP configuration */
 240 #define MAX_PROBERESP_LEN 768
 241         resp = os_zalloc(MAX_PROBERESP_LEN);
 242         if (resp == NULL)
 243                 return;
 244         epos = ((u8 *) resp) + MAX_PROBERESP_LEN;
 245
 246         resp->frame_control = IEEE80211_FC(WLAN_FC_TYPE_MGMT,
 247                                            WLAN_FC_STYPE_PROBE_RESP);
 248         os_memcpy(resp->da, mgmt->sa, ETH_ALEN);
 249         os_memcpy(resp->sa, hapd->own_addr, ETH_ALEN);
 250
 251         os_memcpy(resp->bssid, hapd->own_addr, ETH_ALEN);
 252         resp->u.probe_resp.beacon_int =
 253                 host_to_le16(hapd->iconf->beacon_int);
 254
 255         /* hardware or low-level driver will setup seq_ctrl and timestamp */
 256         resp->u.probe_resp.capab_info =
 257                 host_to_le16(hostapd_own_capab_info(hapd, sta, 1));
 258
 259         pos = resp->u.probe_resp.variable;
 260         *pos++ = WLAN_EID_SSID;
 261         *pos++ = ssid_len;
 262         os_memcpy(pos, ssid, ssid_len);
 263         pos += ssid_len;
 264
 265         /* Supported rates */
 266         pos = hostapd_eid_supp_rates(hapd, pos);
 267
 268         /* DS Params */
 269         pos = hostapd_eid_ds_params(hapd, pos);
 270
 271         pos = hostapd_eid_country(hapd, pos, epos - pos);
 272
 273         pos = hostapd_eid_power_constraint(hapd, pos);
 274         pos = hostapd_eid_tpc_report(hapd, pos);
 275
 276         /* ERP Information element */
 277         pos = hostapd_eid_erp_info(hapd, pos);
 278
 279         /* Extended supported rates */
 280         pos = hostapd_eid_ext_supp_rates(hapd, pos);
 281
 282         pos = hostapd_eid_wpa(hapd, pos, epos - pos, sta);
 283
 284         /* Wi-Fi Wireless Multimedia Extensions */
 285         if (hapd->conf->wme_enabled)
 286                 pos = hostapd_eid_wme(hapd, pos);
 287
 288         if (hostapd_send_mgmt_frame(hapd, resp, pos - (u8 *) resp, 0) < 0)
 289                 perror("handle_probe_req: send");
 290
 291         os_free(resp);
 292
 293         wpa_printf(MSG_MSGDUMP, "STA " MACSTR " sent probe request for %s "
 294                    "SSID", MAC2STR(mgmt->sa),
 295                    elems.ssid_len == 0 ? "broadcast" : "our");
 296 }
 297
 298
 299 void ieee802_11_set_beacon(struct hostapd_data *hapd)
 300 {
 301         struct ieee80211_mgmt *head;
 302         u8 *pos, *tail, *tailpos;
 303         int preamble;
 304         u16 capab_info;
 305         size_t head_len, tail_len;
 306         int cts_protection = ((ieee802_11_erp_info(hapd) &
 307                               ERP_INFO_USE_PROTECTION) ? 1 : 0);
 308
 309 #define BEACON_HEAD_BUF_SIZE 256
 310 #define BEACON_TAIL_BUF_SIZE 512
 311         head = os_zalloc(BEACON_HEAD_BUF_SIZE);
 312         tailpos = tail = os_malloc(BEACON_TAIL_BUF_SIZE);
 313         if (head == NULL || tail == NULL) {
 314                 wpa_printf(MSG_ERROR, "Failed to set beacon data");
 315                 os_free(head);
 316                 os_free(tail);
 317                 return;
 318         }
 319
 320         head->frame_control = IEEE80211_FC(WLAN_FC_TYPE_MGMT,
 321                                            WLAN_FC_STYPE_BEACON);
 322         head->duration = host_to_le16(0);
 323         os_memset(head->da, 0xff, ETH_ALEN);
 324
 325         os_memcpy(head->sa, hapd->own_addr, ETH_ALEN);
 326         os_memcpy(head->bssid, hapd->own_addr, ETH_ALEN);
 327         head->u.beacon.beacon_int =
 328                 host_to_le16(hapd->iconf->beacon_int);
 329
 330         /* hardware or low-level driver will setup seq_ctrl and timestamp */
 331         capab_info = hostapd_own_capab_info(hapd, NULL, 0);
 332         head->u.beacon.capab_info = host_to_le16(capab_info);
 333         pos = &head->u.beacon.variable[0];
 334
 335         /* SSID */
 336         *pos++ = WLAN_EID_SSID;
 337         if (hapd->conf->ignore_broadcast_ssid == 2) {
 338                 /* clear the data, but keep the correct length of the SSID */
 339                 *pos++ = hapd->conf->ssid.ssid_len;
 340                 os_memset(pos, 0, hapd->conf->ssid.ssid_len);
 341                 pos += hapd->conf->ssid.ssid_len;
 342         } else if (hapd->conf->ignore_broadcast_ssid) {
 343                 *pos++ = 0; /* empty SSID */
 344         } else {
 345                 *pos++ = hapd->conf->ssid.ssid_len;
 346                 os_memcpy(pos, hapd->conf->ssid.ssid,
 347                           hapd->conf->ssid.ssid_len);
 348                 pos += hapd->conf->ssid.ssid_len;
 349         }
 350
 351         /* Supported rates */
 352         pos = hostapd_eid_supp_rates(hapd, pos);
 353
 354         /* DS Params */
 355         pos = hostapd_eid_ds_params(hapd, pos);
 356
 357         head_len = pos - (u8 *) head;
 358
 359         tailpos = hostapd_eid_country(hapd, tailpos,
 360                                       tail + BEACON_TAIL_BUF_SIZE - tailpos);
 361
 362         tailpos = hostapd_eid_power_constraint(hapd, tailpos);
 363         tailpos = hostapd_eid_channel_switch(hapd, tailpos);
 364         tailpos = hostapd_eid_tpc_report(hapd, tailpos);
 365
 366         /* ERP Information element */
 367         tailpos = hostapd_eid_erp_info(hapd, tailpos);
 368
 369         /* Extended supported rates */
 370         tailpos = hostapd_eid_ext_supp_rates(hapd, tailpos);
 371
 372         tailpos = hostapd_eid_wpa(hapd, tailpos, tail + BEACON_TAIL_BUF_SIZE -
 373                                   tailpos, NULL);
 374
 375         /* Wi-Fi Wireless Multimedia Extensions */
 376         if (hapd->conf->wme_enabled)
 377                 tailpos = hostapd_eid_wme(hapd, tailpos);
 378
 379         tail_len = tailpos > tail ? tailpos - tail : 0;
 380
 381         if (hostapd_set_beacon(hapd->conf->iface, hapd, (u8 *) head, head_len,
 382                                tail, tail_len))
 383                 wpa_printf(MSG_ERROR, "Failed to set beacon head/tail");
 384
 385         os_free(tail);
 386         os_free(head);
 387
 388         if (hostapd_set_cts_protect(hapd, cts_protection))
 389                 wpa_printf(MSG_ERROR, "Failed to set CTS protect in kernel "
 390                            "driver");
 391
 392         if (hapd->iface->current_mode &&
 393             hapd->iface->current_mode->mode == HOSTAPD_MODE_IEEE80211G &&
 394             hostapd_set_short_slot_time(hapd,
 395                                         hapd->iface->num_sta_no_short_slot_time
 396                                         > 0 ? 0 : 1))
 397                 wpa_printf(MSG_ERROR, "Failed to set Short Slot Time option "
 398                            "in kernel driver");
 399
 400         if (hapd->iface->num_sta_no_short_preamble == 0 &&
 401             hapd->iconf->preamble == SHORT_PREAMBLE)
 402                 preamble = SHORT_PREAMBLE;
 403         else
 404                 preamble = LONG_PREAMBLE;
 405         if (hostapd_set_preamble(hapd, preamble))
 406                 wpa_printf(MSG_ERROR, "Could not set preamble for kernel "
 407                            "driver");
 408 }
 409
 410
 411 void ieee802_11_set_beacons(struct hostapd_iface *iface)
 412 {
 413         size_t i;
 414         for (i = 0; i < iface->num_bss; i++)
 415                 ieee802_11_set_beacon(iface->bss[i]);
 416 }
 417
 418 #endif /* CONFIG_NATIVE_WINDOWS */