beacon.c revision 214501 
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
34static 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	    hapd->iconf->preamble == LONG_PREAMBLE)
62		erp |= ERP_INFO_BARKER_PREAMBLE_MODE;
63
64	return erp;
65}
66
67
68static u8 * hostapd_eid_ds_params(struct hostapd_data *hapd, u8 *eid)
69{
70	*eid++ = WLAN_EID_DS_PARAMS;
71	*eid++ = 1;
72	*eid++ = hapd->iconf->channel;
73	return eid;
74}
75
76
77static u8 * hostapd_eid_erp_info(struct hostapd_data *hapd, u8 *eid)
78{
79	if (hapd->iface->current_mode == NULL ||
80	    hapd->iface->current_mode->mode != HOSTAPD_MODE_IEEE80211G)
81		return eid;
82
83	/* Set NonERP_present and use_protection bits if there
84	 * are any associated NonERP stations. */
85	/* TODO: use_protection bit can be set to zero even if
86	 * there are NonERP stations present. This optimization
87	 * might be useful if NonERP stations are "quiet".
88	 * See 802.11g/D6 E-1 for recommended practice.
89	 * In addition, Non ERP present might be set, if AP detects Non ERP
90	 * operation on other APs. */
91
92	/* Add ERP Information element */
93	*eid++ = WLAN_EID_ERP_INFO;
94	*eid++ = 1;
95	*eid++ = ieee802_11_erp_info(hapd);
96
97	return eid;
98}
99
100
101static u8 * hostapd_eid_country_add(u8 *pos, u8 *end, int chan_spacing,
102				    struct hostapd_channel_data *start,
103				    struct hostapd_channel_data *prev)
104{
105	if (end - pos < 3)
106		return pos;
107
108	/* first channel number */
109	*pos++ = start->chan;
110	/* number of channels */
111	*pos++ = (prev->chan - start->chan) / chan_spacing + 1;
112	/* maximum transmit power level */
113	*pos++ = start->max_tx_power;
114
115	return pos;
116}
117
118
119static u8 * hostapd_eid_country(struct hostapd_data *hapd, u8 *eid,
120				int max_len)
121{
122	u8 *pos = eid;
123	u8 *end = eid + max_len;
124	int i;
125	struct hostapd_hw_modes *mode;
126	struct hostapd_channel_data *start, *prev;
127	int chan_spacing = 1;
128
129	if (!hapd->iconf->ieee80211d || max_len < 6 ||
130	    hapd->iface->current_mode == NULL)
131		return eid;
132
133	*pos++ = WLAN_EID_COUNTRY;
134	pos++; /* length will be set later */
135	os_memcpy(pos, hapd->iconf->country, 3); /* e.g., 'US ' */
136	pos += 3;
137
138	mode = hapd->iface->current_mode;
139	if (mode->mode == HOSTAPD_MODE_IEEE80211A)
140		chan_spacing = 4;
141
142	start = prev = NULL;
143	for (i = 0; i < mode->num_channels; i++) {
144		struct hostapd_channel_data *chan = &mode->channels[i];
145		if (chan->flag & HOSTAPD_CHAN_DISABLED)
146			continue;
147		if (start && prev &&
148		    prev->chan + chan_spacing == chan->chan &&
149		    start->max_tx_power == chan->max_tx_power) {
150			prev = chan;
151			continue; /* can use same entry */
152		}
153
154		if (start) {
155			pos = hostapd_eid_country_add(pos, end, chan_spacing,
156						      start, prev);
157			start = NULL;
158		}
159
160		/* Start new group */
161		start = prev = chan;
162	}
163
164	if (start) {
165		pos = hostapd_eid_country_add(pos, end, chan_spacing,
166					      start, prev);
167	}
168
169	if ((pos - eid) & 1) {
170		if (end - pos < 1)
171			return eid;
172		*pos++ = 0; /* pad for 16-bit alignment */
173	}
174
175	eid[1] = (pos - eid) - 2;
176
177	return pos;
178}
179
180
181static u8 * hostapd_eid_wpa(struct hostapd_data *hapd, u8 *eid, size_t len,
182			    struct sta_info *sta)
183{
184	const u8 *ie;
185	size_t ielen;
186
187	ie = wpa_auth_get_wpa_ie(hapd->wpa_auth, &ielen);
188	if (ie == NULL || ielen > len)
189		return eid;
190
191	os_memcpy(eid, ie, ielen);
192	return eid + ielen;
193}
194
195
196void handle_probe_req(struct hostapd_data *hapd,
197		      const struct ieee80211_mgmt *mgmt, size_t len)
198{
199	struct ieee80211_mgmt *resp;
200	struct ieee802_11_elems elems;
201	char *ssid;
202	u8 *pos, *epos;
203	const u8 *ie;
204	size_t ssid_len, ie_len;
205	struct sta_info *sta = NULL;
206	size_t buflen;
207	size_t i;
208
209	ie = mgmt->u.probe_req.variable;
210	ie_len = len - (IEEE80211_HDRLEN + sizeof(mgmt->u.probe_req));
211
212	for (i = 0; hapd->probereq_cb && i < hapd->num_probereq_cb; i++)
213		if (hapd->probereq_cb[i].cb(hapd->probereq_cb[i].ctx,
214					    mgmt->sa, ie, ie_len) > 0)
215			return;
216
217	if (!hapd->iconf->send_probe_response)
218		return;
219
220	if (ieee802_11_parse_elems(ie, ie_len, &elems, 0) == ParseFailed) {
221		wpa_printf(MSG_DEBUG, "Could not parse ProbeReq from " MACSTR,
222			   MAC2STR(mgmt->sa));
223		return;
224	}
225
226	ssid = NULL;
227	ssid_len = 0;
228
229	if ((!elems.ssid || !elems.supp_rates)) {
230		wpa_printf(MSG_DEBUG, "STA " MACSTR " sent probe request "
231			   "without SSID or supported rates element",
232			   MAC2STR(mgmt->sa));
233		return;
234	}
235
236	if (hapd->conf->ignore_broadcast_ssid && elems.ssid_len == 0) {
237		wpa_printf(MSG_MSGDUMP, "Probe Request from " MACSTR " for "
238			   "broadcast SSID ignored", MAC2STR(mgmt->sa));
239		return;
240	}
241
242	sta = ap_get_sta(hapd, mgmt->sa);
243
244	if (elems.ssid_len == 0 ||
245	    (elems.ssid_len == hapd->conf->ssid.ssid_len &&
246	     os_memcmp(elems.ssid, hapd->conf->ssid.ssid, elems.ssid_len) ==
247	     0)) {
248		ssid = hapd->conf->ssid.ssid;
249		ssid_len = hapd->conf->ssid.ssid_len;
250		if (sta)
251			sta->ssid_probe = &hapd->conf->ssid;
252	}
253
254	if (!ssid) {
255		if (!(mgmt->da[0] & 0x01)) {
256			char ssid_txt[33];
257			ieee802_11_print_ssid(ssid_txt, elems.ssid,
258					      elems.ssid_len);
259			wpa_printf(MSG_MSGDUMP, "Probe Request from " MACSTR
260				   " for foreign SSID '%s'",
261				   MAC2STR(mgmt->sa), ssid_txt);
262		}
263		return;
264	}
265
266	/* TODO: verify that supp_rates contains at least one matching rate
267	 * with AP configuration */
268#define MAX_PROBERESP_LEN 768
269	buflen = MAX_PROBERESP_LEN;
270#ifdef CONFIG_WPS
271	if (hapd->wps_probe_resp_ie)
272		buflen += wpabuf_len(hapd->wps_probe_resp_ie);
273#endif /* CONFIG_WPS */
274	resp = os_zalloc(buflen);
275	if (resp == NULL)
276		return;
277	epos = ((u8 *) resp) + MAX_PROBERESP_LEN;
278
279	resp->frame_control = IEEE80211_FC(WLAN_FC_TYPE_MGMT,
280					   WLAN_FC_STYPE_PROBE_RESP);
281	os_memcpy(resp->da, mgmt->sa, ETH_ALEN);
282	os_memcpy(resp->sa, hapd->own_addr, ETH_ALEN);
283
284	os_memcpy(resp->bssid, hapd->own_addr, ETH_ALEN);
285	resp->u.probe_resp.beacon_int =
286		host_to_le16(hapd->iconf->beacon_int);
287
288	/* hardware or low-level driver will setup seq_ctrl and timestamp */
289	resp->u.probe_resp.capab_info =
290		host_to_le16(hostapd_own_capab_info(hapd, sta, 1));
291
292	pos = resp->u.probe_resp.variable;
293	*pos++ = WLAN_EID_SSID;
294	*pos++ = ssid_len;
295	os_memcpy(pos, ssid, ssid_len);
296	pos += ssid_len;
297
298	/* Supported rates */
299	pos = hostapd_eid_supp_rates(hapd, pos);
300
301	/* DS Params */
302	pos = hostapd_eid_ds_params(hapd, pos);
303
304	pos = hostapd_eid_country(hapd, pos, epos - pos);
305
306	/* ERP Information element */
307	pos = hostapd_eid_erp_info(hapd, pos);
308
309	/* Extended supported rates */
310	pos = hostapd_eid_ext_supp_rates(hapd, pos);
311
312	/* RSN, MDIE, WPA */
313	pos = hostapd_eid_wpa(hapd, pos, epos - pos, sta);
314
315#ifdef CONFIG_IEEE80211N
316	pos = hostapd_eid_ht_capabilities(hapd, pos);
317	pos = hostapd_eid_ht_operation(hapd, pos);
318#endif /* CONFIG_IEEE80211N */
319
320	/* Wi-Fi Alliance WMM */
321	pos = hostapd_eid_wmm(hapd, pos);
322
323#ifdef CONFIG_WPS
324	if (hapd->conf->wps_state && hapd->wps_probe_resp_ie) {
325		os_memcpy(pos, wpabuf_head(hapd->wps_probe_resp_ie),
326			  wpabuf_len(hapd->wps_probe_resp_ie));
327		pos += wpabuf_len(hapd->wps_probe_resp_ie);
328	}
329#endif /* CONFIG_WPS */
330
331	if (hapd->drv.send_mgmt_frame(hapd, resp, pos - (u8 *) resp) < 0)
332		perror("handle_probe_req: send");
333
334	os_free(resp);
335
336	wpa_printf(MSG_MSGDUMP, "STA " MACSTR " sent probe request for %s "
337		   "SSID", MAC2STR(mgmt->sa),
338		   elems.ssid_len == 0 ? "broadcast" : "our");
339}
340
341
342void ieee802_11_set_beacon(struct hostapd_data *hapd)
343{
344	struct ieee80211_mgmt *head;
345	u8 *pos, *tail, *tailpos;
346	u16 capab_info;
347	size_t head_len, tail_len;
348
349#define BEACON_HEAD_BUF_SIZE 256
350#define BEACON_TAIL_BUF_SIZE 512
351	head = os_zalloc(BEACON_HEAD_BUF_SIZE);
352	tail_len = BEACON_TAIL_BUF_SIZE;
353#ifdef CONFIG_WPS
354	if (hapd->conf->wps_state && hapd->wps_beacon_ie)
355		tail_len += wpabuf_len(hapd->wps_beacon_ie);
356#endif /* CONFIG_WPS */
357	tailpos = tail = os_malloc(tail_len);
358	if (head == NULL || tail == NULL) {
359		wpa_printf(MSG_ERROR, "Failed to set beacon data");
360		os_free(head);
361		os_free(tail);
362		return;
363	}
364
365	head->frame_control = IEEE80211_FC(WLAN_FC_TYPE_MGMT,
366					   WLAN_FC_STYPE_BEACON);
367	head->duration = host_to_le16(0);
368	os_memset(head->da, 0xff, ETH_ALEN);
369
370	os_memcpy(head->sa, hapd->own_addr, ETH_ALEN);
371	os_memcpy(head->bssid, hapd->own_addr, ETH_ALEN);
372	head->u.beacon.beacon_int =
373		host_to_le16(hapd->iconf->beacon_int);
374
375	/* hardware or low-level driver will setup seq_ctrl and timestamp */
376	capab_info = hostapd_own_capab_info(hapd, NULL, 0);
377	head->u.beacon.capab_info = host_to_le16(capab_info);
378	pos = &head->u.beacon.variable[0];
379
380	/* SSID */
381	*pos++ = WLAN_EID_SSID;
382	if (hapd->conf->ignore_broadcast_ssid == 2) {
383		/* clear the data, but keep the correct length of the SSID */
384		*pos++ = hapd->conf->ssid.ssid_len;
385		os_memset(pos, 0, hapd->conf->ssid.ssid_len);
386		pos += hapd->conf->ssid.ssid_len;
387	} else if (hapd->conf->ignore_broadcast_ssid) {
388		*pos++ = 0; /* empty SSID */
389	} else {
390		*pos++ = hapd->conf->ssid.ssid_len;
391		os_memcpy(pos, hapd->conf->ssid.ssid,
392			  hapd->conf->ssid.ssid_len);
393		pos += hapd->conf->ssid.ssid_len;
394	}
395
396	/* Supported rates */
397	pos = hostapd_eid_supp_rates(hapd, pos);
398
399	/* DS Params */
400	pos = hostapd_eid_ds_params(hapd, pos);
401
402	head_len = pos - (u8 *) head;
403
404	tailpos = hostapd_eid_country(hapd, tailpos,
405				      tail + BEACON_TAIL_BUF_SIZE - tailpos);
406
407	/* ERP Information element */
408	tailpos = hostapd_eid_erp_info(hapd, tailpos);
409
410	/* Extended supported rates */
411	tailpos = hostapd_eid_ext_supp_rates(hapd, tailpos);
412
413	/* RSN, MDIE, WPA */
414	tailpos = hostapd_eid_wpa(hapd, tailpos, tail + BEACON_TAIL_BUF_SIZE -
415				  tailpos, NULL);
416
417#ifdef CONFIG_IEEE80211N
418	tailpos = hostapd_eid_ht_capabilities(hapd, tailpos);
419	tailpos = hostapd_eid_ht_operation(hapd, tailpos);
420#endif /* CONFIG_IEEE80211N */
421
422	/* Wi-Fi Alliance WMM */
423	tailpos = hostapd_eid_wmm(hapd, tailpos);
424
425#ifdef CONFIG_WPS
426	if (hapd->conf->wps_state && hapd->wps_beacon_ie) {
427		os_memcpy(tailpos, wpabuf_head(hapd->wps_beacon_ie),
428			  wpabuf_len(hapd->wps_beacon_ie));
429		tailpos += wpabuf_len(hapd->wps_beacon_ie);
430	}
431#endif /* CONFIG_WPS */
432
433	tail_len = tailpos > tail ? tailpos - tail : 0;
434
435	if (hapd->drv.set_beacon(hapd, (u8 *) head, head_len,
436				 tail, tail_len, hapd->conf->dtim_period,
437				 hapd->iconf->beacon_int))
438		wpa_printf(MSG_ERROR, "Failed to set beacon head/tail or DTIM "
439			   "period");
440
441	os_free(tail);
442	os_free(head);
443
444	hapd->drv.set_bss_params(hapd, !!(ieee802_11_erp_info(hapd) &
445					  ERP_INFO_USE_PROTECTION));
446}
447
448
449void ieee802_11_set_beacons(struct hostapd_iface *iface)
450{
451	size_t i;
452	for (i = 0; i < iface->num_bss; i++)
453		ieee802_11_set_beacon(iface->bss[i]);
454}
455
456#endif /* CONFIG_NATIVE_WINDOWS */
457