1 /*
2  * Generic advertisement service (GAS) query (hostapd)
3  * Copyright (c) 2009, Atheros Communications
4  * Copyright (c) 2011-2017, Qualcomm Atheros, Inc.
5  * Copyright (c) 2011-2014, Jouni Malinen <j@w1.fi>
6  *
7  * This software may be distributed under the terms of the BSD license.
8  * See README for more details.
9  */
10 
11 #include "includes.h"
12 
13 #include "common.h"
14 #include "utils/eloop.h"
15 #include "utils/list.h"
16 #include "common/ieee802_11_defs.h"
17 #include "common/gas.h"
18 #include "common/wpa_ctrl.h"
19 #include "hostapd.h"
20 #include "sta_info.h"
21 #include "ap_drv_ops.h"
22 #include "gas_query_ap.h"
23 
24 
25 /** GAS query timeout in seconds */
26 #define GAS_QUERY_TIMEOUT_PERIOD 2
27 
28 /* GAS query wait-time / duration in ms */
29 #define GAS_QUERY_WAIT_TIME_INITIAL 1000
30 #define GAS_QUERY_WAIT_TIME_COMEBACK 150
31 
32 /**
33  * struct gas_query_pending - Pending GAS query
34  */
35 struct gas_query_pending {
36 	struct dl_list list;
37 	struct gas_query_ap *gas;
38 	u8 addr[ETH_ALEN];
39 	u8 dialog_token;
40 	u8 next_frag_id;
41 	unsigned int wait_comeback:1;
42 	unsigned int offchannel_tx_started:1;
43 	unsigned int retry:1;
44 	int freq;
45 	u16 status_code;
46 	struct wpabuf *req;
47 	struct wpabuf *adv_proto;
48 	struct wpabuf *resp;
49 	struct os_reltime last_oper;
50 	void (*cb)(void *ctx, const u8 *dst, u8 dialog_token,
51 		   enum gas_query_ap_result result,
52 		   const struct wpabuf *adv_proto,
53 		   const struct wpabuf *resp, u16 status_code);
54 	void *ctx;
55 	u8 sa[ETH_ALEN];
56 };
57 
58 /**
59  * struct gas_query_ap - Internal GAS query data
60  */
61 struct gas_query_ap {
62 	struct hostapd_data *hapd;
63 	void *msg_ctx;
64 	struct dl_list pending; /* struct gas_query_pending */
65 	struct gas_query_pending *current;
66 };
67 
68 
69 static void gas_query_tx_comeback_timeout(void *eloop_data, void *user_ctx);
70 static void gas_query_timeout(void *eloop_data, void *user_ctx);
71 static void gas_query_rx_comeback_timeout(void *eloop_data, void *user_ctx);
72 static void gas_query_tx_initial_req(struct gas_query_ap *gas,
73 				     struct gas_query_pending *query);
74 static int gas_query_new_dialog_token(struct gas_query_ap *gas, const u8 *dst);
75 
76 
77 static int ms_from_time(struct os_reltime *last)
78 {
79 	struct os_reltime now, res;
80 
81 	os_get_reltime(&now);
82 	os_reltime_sub(&now, last, &res);
83 	return res.sec * 1000 + res.usec / 1000;
84 }
85 
86 
87 /**
88  * gas_query_ap_init - Initialize GAS query component
89  * @hapd: Pointer to hostapd data
90  * Returns: Pointer to GAS query data or %NULL on failure
91  */
92 struct gas_query_ap * gas_query_ap_init(struct hostapd_data *hapd,
93 					void *msg_ctx)
94 {
95 	struct gas_query_ap *gas;
96 
97 	gas = os_zalloc(sizeof(*gas));
98 	if (!gas)
99 		return NULL;
100 
101 	gas->hapd = hapd;
102 	gas->msg_ctx = msg_ctx;
103 	dl_list_init(&gas->pending);
104 
105 	return gas;
106 }
107 
108 
109 static const char * gas_result_txt(enum gas_query_ap_result result)
110 {
111 	switch (result) {
112 	case GAS_QUERY_AP_SUCCESS:
113 		return "SUCCESS";
114 	case GAS_QUERY_AP_FAILURE:
115 		return "FAILURE";
116 	case GAS_QUERY_AP_TIMEOUT:
117 		return "TIMEOUT";
118 	case GAS_QUERY_AP_PEER_ERROR:
119 		return "PEER_ERROR";
120 	case GAS_QUERY_AP_INTERNAL_ERROR:
121 		return "INTERNAL_ERROR";
122 	case GAS_QUERY_AP_DELETED_AT_DEINIT:
123 		return "DELETED_AT_DEINIT";
124 	}
125 
126 	return "N/A";
127 }
128 
129 
130 static void gas_query_free(struct gas_query_pending *query, int del_list)
131 {
132 	if (del_list)
133 		dl_list_del(&query->list);
134 
135 	wpabuf_free(query->req);
136 	wpabuf_free(query->adv_proto);
137 	wpabuf_free(query->resp);
138 	os_free(query);
139 }
140 
141 
142 static void gas_query_done(struct gas_query_ap *gas,
143 			   struct gas_query_pending *query,
144 			   enum gas_query_ap_result result)
145 {
146 	wpa_msg(gas->msg_ctx, MSG_INFO, GAS_QUERY_DONE "addr=" MACSTR
147 		" dialog_token=%u freq=%d status_code=%u result=%s",
148 		MAC2STR(query->addr), query->dialog_token, query->freq,
149 		query->status_code, gas_result_txt(result));
150 	if (gas->current == query)
151 		gas->current = NULL;
152 	eloop_cancel_timeout(gas_query_tx_comeback_timeout, gas, query);
153 	eloop_cancel_timeout(gas_query_timeout, gas, query);
154 	eloop_cancel_timeout(gas_query_rx_comeback_timeout, gas, query);
155 	dl_list_del(&query->list);
156 	query->cb(query->ctx, query->addr, query->dialog_token, result,
157 		  query->adv_proto, query->resp, query->status_code);
158 	gas_query_free(query, 0);
159 }
160 
161 
162 /**
163  * gas_query_ap_deinit - Deinitialize GAS query component
164  * @gas: GAS query data from gas_query_init()
165  */
166 void gas_query_ap_deinit(struct gas_query_ap *gas)
167 {
168 	struct gas_query_pending *query, *next;
169 
170 	if (gas == NULL)
171 		return;
172 
173 	dl_list_for_each_safe(query, next, &gas->pending,
174 			      struct gas_query_pending, list)
175 		gas_query_done(gas, query, GAS_QUERY_AP_DELETED_AT_DEINIT);
176 
177 	os_free(gas);
178 }
179 
180 
181 static struct gas_query_pending *
182 gas_query_get_pending(struct gas_query_ap *gas, const u8 *addr, u8 dialog_token)
183 {
184 	struct gas_query_pending *q;
185 	dl_list_for_each(q, &gas->pending, struct gas_query_pending, list) {
186 		if (os_memcmp(q->addr, addr, ETH_ALEN) == 0 &&
187 		    q->dialog_token == dialog_token)
188 			return q;
189 	}
190 	return NULL;
191 }
192 
193 
194 static int gas_query_append(struct gas_query_pending *query, const u8 *data,
195 			    size_t len)
196 {
197 	if (wpabuf_resize(&query->resp, len) < 0) {
198 		wpa_printf(MSG_DEBUG, "GAS: No memory to store the response");
199 		return -1;
200 	}
201 	wpabuf_put_data(query->resp, data, len);
202 	return 0;
203 }
204 
205 
206 void gas_query_ap_tx_status(struct gas_query_ap *gas, const u8 *dst,
207 			    const u8 *data, size_t data_len, int ok)
208 {
209 	struct gas_query_pending *query;
210 	int dur;
211 
212 	if (!gas || !gas->current) {
213 		wpa_printf(MSG_DEBUG, "GAS: Unexpected TX status: dst=" MACSTR
214 			   " ok=%d - no query in progress", MAC2STR(dst), ok);
215 		return;
216 	}
217 
218 	query = gas->current;
219 
220 	dur = ms_from_time(&query->last_oper);
221 	wpa_printf(MSG_DEBUG, "GAS: TX status: dst=" MACSTR
222 		   " ok=%d query=%p dialog_token=%u dur=%d ms",
223 		   MAC2STR(dst), ok, query, query->dialog_token, dur);
224 	if (os_memcmp(dst, query->addr, ETH_ALEN) != 0) {
225 		wpa_printf(MSG_DEBUG, "GAS: TX status for unexpected destination");
226 		return;
227 	}
228 	os_get_reltime(&query->last_oper);
229 
230 	eloop_cancel_timeout(gas_query_timeout, gas, query);
231 	if (!ok) {
232 		wpa_printf(MSG_DEBUG, "GAS: No ACK to GAS request");
233 		eloop_register_timeout(0, 250000, gas_query_timeout,
234 				       gas, query);
235 	} else {
236 		eloop_register_timeout(GAS_QUERY_TIMEOUT_PERIOD, 0,
237 				       gas_query_timeout, gas, query);
238 	}
239 	if (query->wait_comeback && !query->retry) {
240 		eloop_cancel_timeout(gas_query_rx_comeback_timeout,
241 				     gas, query);
242 		eloop_register_timeout(
243 			0, (GAS_QUERY_WAIT_TIME_COMEBACK + 10) * 1000,
244 			gas_query_rx_comeback_timeout, gas, query);
245 	}
246 }
247 
248 
249 static int pmf_in_use(struct hostapd_data *hapd, const u8 *addr)
250 {
251 	struct sta_info *sta;
252 
253 	sta = ap_get_sta(hapd, addr);
254 	return sta && (sta->flags & WLAN_STA_MFP);
255 }
256 
257 
258 static int gas_query_tx(struct gas_query_ap *gas,
259 			struct gas_query_pending *query,
260 			struct wpabuf *req, unsigned int wait_time)
261 {
262 	int res, prot = pmf_in_use(gas->hapd, query->addr);
263 
264 	wpa_printf(MSG_DEBUG, "GAS: Send action frame to " MACSTR " len=%u "
265 		   "freq=%d prot=%d using src addr " MACSTR,
266 		   MAC2STR(query->addr), (unsigned int) wpabuf_len(req),
267 		   query->freq, prot, MAC2STR(query->sa));
268 	if (prot) {
269 		u8 *categ = wpabuf_mhead_u8(req);
270 		*categ = WLAN_ACTION_PROTECTED_DUAL;
271 	}
272 	os_get_reltime(&query->last_oper);
273 	res = hostapd_drv_send_action(gas->hapd, query->freq, wait_time,
274 				      query->addr, wpabuf_head(req),
275 				      wpabuf_len(req));
276 	return res;
277 }
278 
279 
280 static void gas_query_tx_comeback_req(struct gas_query_ap *gas,
281 				      struct gas_query_pending *query)
282 {
283 	struct wpabuf *req;
284 	unsigned int wait_time;
285 
286 	req = gas_build_comeback_req(query->dialog_token);
287 	if (req == NULL) {
288 		gas_query_done(gas, query, GAS_QUERY_AP_INTERNAL_ERROR);
289 		return;
290 	}
291 
292 	wait_time = (query->retry || !query->offchannel_tx_started) ?
293 		GAS_QUERY_WAIT_TIME_INITIAL : GAS_QUERY_WAIT_TIME_COMEBACK;
294 
295 	if (gas_query_tx(gas, query, req, wait_time) < 0) {
296 		wpa_printf(MSG_DEBUG, "GAS: Failed to send Action frame to "
297 			   MACSTR, MAC2STR(query->addr));
298 		gas_query_done(gas, query, GAS_QUERY_AP_INTERNAL_ERROR);
299 	}
300 
301 	wpabuf_free(req);
302 }
303 
304 
305 static void gas_query_rx_comeback_timeout(void *eloop_data, void *user_ctx)
306 {
307 	struct gas_query_ap *gas = eloop_data;
308 	struct gas_query_pending *query = user_ctx;
309 	int dialog_token;
310 
311 	wpa_printf(MSG_DEBUG,
312 		   "GAS: No response to comeback request received (retry=%u)",
313 		   query->retry);
314 	if (gas->current != query || query->retry)
315 		return;
316 	dialog_token = gas_query_new_dialog_token(gas, query->addr);
317 	if (dialog_token < 0)
318 		return;
319 	wpa_printf(MSG_DEBUG,
320 		   "GAS: Retry GAS query due to comeback response timeout");
321 	query->retry = 1;
322 	query->dialog_token = dialog_token;
323 	*(wpabuf_mhead_u8(query->req) + 2) = dialog_token;
324 	query->wait_comeback = 0;
325 	query->next_frag_id = 0;
326 	wpabuf_free(query->adv_proto);
327 	query->adv_proto = NULL;
328 	eloop_cancel_timeout(gas_query_tx_comeback_timeout, gas, query);
329 	eloop_cancel_timeout(gas_query_timeout, gas, query);
330 	gas_query_tx_initial_req(gas, query);
331 }
332 
333 
334 static void gas_query_tx_comeback_timeout(void *eloop_data, void *user_ctx)
335 {
336 	struct gas_query_ap *gas = eloop_data;
337 	struct gas_query_pending *query = user_ctx;
338 
339 	wpa_printf(MSG_DEBUG, "GAS: Comeback timeout for request to " MACSTR,
340 		   MAC2STR(query->addr));
341 	gas_query_tx_comeback_req(gas, query);
342 }
343 
344 
345 static void gas_query_tx_comeback_req_delay(struct gas_query_ap *gas,
346 					    struct gas_query_pending *query,
347 					    u16 comeback_delay)
348 {
349 	unsigned int secs, usecs;
350 
351 	secs = (comeback_delay * 1024) / 1000000;
352 	usecs = comeback_delay * 1024 - secs * 1000000;
353 	wpa_printf(MSG_DEBUG, "GAS: Send comeback request to " MACSTR
354 		   " in %u secs %u usecs", MAC2STR(query->addr), secs, usecs);
355 	eloop_cancel_timeout(gas_query_tx_comeback_timeout, gas, query);
356 	eloop_register_timeout(secs, usecs, gas_query_tx_comeback_timeout,
357 			       gas, query);
358 }
359 
360 
361 static void gas_query_rx_initial(struct gas_query_ap *gas,
362 				 struct gas_query_pending *query,
363 				 const u8 *adv_proto, const u8 *resp,
364 				 size_t len, u16 comeback_delay)
365 {
366 	wpa_printf(MSG_DEBUG, "GAS: Received initial response from "
367 		   MACSTR " (dialog_token=%u comeback_delay=%u)",
368 		   MAC2STR(query->addr), query->dialog_token, comeback_delay);
369 
370 	query->adv_proto = wpabuf_alloc_copy(adv_proto, 2 + adv_proto[1]);
371 	if (query->adv_proto == NULL) {
372 		gas_query_done(gas, query, GAS_QUERY_AP_INTERNAL_ERROR);
373 		return;
374 	}
375 
376 	if (comeback_delay) {
377 		eloop_cancel_timeout(gas_query_timeout, gas, query);
378 		query->wait_comeback = 1;
379 		gas_query_tx_comeback_req_delay(gas, query, comeback_delay);
380 		return;
381 	}
382 
383 	/* Query was completed without comeback mechanism */
384 	if (gas_query_append(query, resp, len) < 0) {
385 		gas_query_done(gas, query, GAS_QUERY_AP_INTERNAL_ERROR);
386 		return;
387 	}
388 
389 	gas_query_done(gas, query, GAS_QUERY_AP_SUCCESS);
390 }
391 
392 
393 static void gas_query_rx_comeback(struct gas_query_ap *gas,
394 				  struct gas_query_pending *query,
395 				  const u8 *adv_proto, const u8 *resp,
396 				  size_t len, u8 frag_id, u8 more_frags,
397 				  u16 comeback_delay)
398 {
399 	wpa_printf(MSG_DEBUG, "GAS: Received comeback response from "
400 		   MACSTR " (dialog_token=%u frag_id=%u more_frags=%u "
401 		   "comeback_delay=%u)",
402 		   MAC2STR(query->addr), query->dialog_token, frag_id,
403 		   more_frags, comeback_delay);
404 	eloop_cancel_timeout(gas_query_rx_comeback_timeout, gas, query);
405 
406 	if ((size_t) 2 + adv_proto[1] != wpabuf_len(query->adv_proto) ||
407 	    os_memcmp(adv_proto, wpabuf_head(query->adv_proto),
408 		      wpabuf_len(query->adv_proto)) != 0) {
409 		wpa_printf(MSG_DEBUG, "GAS: Advertisement Protocol changed "
410 			   "between initial and comeback response from "
411 			   MACSTR, MAC2STR(query->addr));
412 		gas_query_done(gas, query, GAS_QUERY_AP_PEER_ERROR);
413 		return;
414 	}
415 
416 	if (comeback_delay) {
417 		if (frag_id) {
418 			wpa_printf(MSG_DEBUG, "GAS: Invalid comeback response "
419 				   "with non-zero frag_id and comeback_delay "
420 				   "from " MACSTR, MAC2STR(query->addr));
421 			gas_query_done(gas, query, GAS_QUERY_AP_PEER_ERROR);
422 			return;
423 		}
424 		gas_query_tx_comeback_req_delay(gas, query, comeback_delay);
425 		return;
426 	}
427 
428 	if (frag_id != query->next_frag_id) {
429 		wpa_printf(MSG_DEBUG, "GAS: Unexpected frag_id in response "
430 			   "from " MACSTR, MAC2STR(query->addr));
431 		if (frag_id + 1 == query->next_frag_id) {
432 			wpa_printf(MSG_DEBUG, "GAS: Drop frame as possible "
433 				   "retry of previous fragment");
434 			return;
435 		}
436 		gas_query_done(gas, query, GAS_QUERY_AP_PEER_ERROR);
437 		return;
438 	}
439 	query->next_frag_id++;
440 
441 	if (gas_query_append(query, resp, len) < 0) {
442 		gas_query_done(gas, query, GAS_QUERY_AP_INTERNAL_ERROR);
443 		return;
444 	}
445 
446 	if (more_frags) {
447 		gas_query_tx_comeback_req(gas, query);
448 		return;
449 	}
450 
451 	gas_query_done(gas, query, GAS_QUERY_AP_SUCCESS);
452 }
453 
454 
455 /**
456  * gas_query_ap_rx - Indicate reception of a Public Action or Protected Dual
457  *	frame
458  * @gas: GAS query data from gas_query_init()
459  * @sa: Source MAC address of the Action frame
460  * @categ: Category of the Action frame
461  * @data: Payload of the Action frame
462  * @len: Length of @data
463  * @freq: Frequency (in MHz) on which the frame was received
464  * Returns: 0 if the Public Action frame was a GAS frame or -1 if not
465  */
466 int gas_query_ap_rx(struct gas_query_ap *gas, const u8 *sa, u8 categ,
467 		    const u8 *data, size_t len, int freq)
468 {
469 	struct gas_query_pending *query;
470 	u8 action, dialog_token, frag_id = 0, more_frags = 0;
471 	u16 comeback_delay, resp_len;
472 	const u8 *pos, *adv_proto;
473 	int prot, pmf;
474 	unsigned int left;
475 
476 	if (!gas || len < 4)
477 		return -1;
478 
479 	pos = data;
480 	action = *pos++;
481 	dialog_token = *pos++;
482 
483 	if (action != WLAN_PA_GAS_INITIAL_RESP &&
484 	    action != WLAN_PA_GAS_COMEBACK_RESP)
485 		return -1; /* Not a GAS response */
486 
487 	prot = categ == WLAN_ACTION_PROTECTED_DUAL;
488 	pmf = pmf_in_use(gas->hapd, sa);
489 	if (prot && !pmf) {
490 		wpa_printf(MSG_DEBUG, "GAS: Drop unexpected protected GAS frame when PMF is disabled");
491 		return 0;
492 	}
493 	if (!prot && pmf) {
494 		wpa_printf(MSG_DEBUG, "GAS: Drop unexpected unprotected GAS frame when PMF is enabled");
495 		return 0;
496 	}
497 
498 	query = gas_query_get_pending(gas, sa, dialog_token);
499 	if (query == NULL) {
500 		wpa_printf(MSG_DEBUG, "GAS: No pending query found for " MACSTR
501 			   " dialog token %u", MAC2STR(sa), dialog_token);
502 		return -1;
503 	}
504 
505 	wpa_printf(MSG_DEBUG, "GAS: Response in %d ms from " MACSTR,
506 		   ms_from_time(&query->last_oper), MAC2STR(sa));
507 
508 	if (query->wait_comeback && action == WLAN_PA_GAS_INITIAL_RESP) {
509 		wpa_printf(MSG_DEBUG, "GAS: Unexpected initial response from "
510 			   MACSTR " dialog token %u when waiting for comeback "
511 			   "response", MAC2STR(sa), dialog_token);
512 		return 0;
513 	}
514 
515 	if (!query->wait_comeback && action == WLAN_PA_GAS_COMEBACK_RESP) {
516 		wpa_printf(MSG_DEBUG, "GAS: Unexpected comeback response from "
517 			   MACSTR " dialog token %u when waiting for initial "
518 			   "response", MAC2STR(sa), dialog_token);
519 		return 0;
520 	}
521 
522 	query->status_code = WPA_GET_LE16(pos);
523 	pos += 2;
524 
525 	if (query->status_code == WLAN_STATUS_QUERY_RESP_OUTSTANDING &&
526 	    action == WLAN_PA_GAS_COMEBACK_RESP) {
527 		wpa_printf(MSG_DEBUG, "GAS: Allow non-zero status for outstanding comeback response");
528 	} else if (query->status_code != WLAN_STATUS_SUCCESS) {
529 		wpa_printf(MSG_DEBUG, "GAS: Query to " MACSTR " dialog token "
530 			   "%u failed - status code %u",
531 			   MAC2STR(sa), dialog_token, query->status_code);
532 		gas_query_done(gas, query, GAS_QUERY_AP_FAILURE);
533 		return 0;
534 	}
535 
536 	if (action == WLAN_PA_GAS_COMEBACK_RESP) {
537 		if (pos + 1 > data + len)
538 			return 0;
539 		frag_id = *pos & 0x7f;
540 		more_frags = (*pos & 0x80) >> 7;
541 		pos++;
542 	}
543 
544 	/* Comeback Delay */
545 	if (pos + 2 > data + len)
546 		return 0;
547 	comeback_delay = WPA_GET_LE16(pos);
548 	pos += 2;
549 
550 	/* Advertisement Protocol element */
551 	if (pos + 2 > data + len || pos + 2 + pos[1] > data + len) {
552 		wpa_printf(MSG_DEBUG, "GAS: No room for Advertisement "
553 			   "Protocol element in the response from " MACSTR,
554 			   MAC2STR(sa));
555 		return 0;
556 	}
557 
558 	if (*pos != WLAN_EID_ADV_PROTO) {
559 		wpa_printf(MSG_DEBUG, "GAS: Unexpected Advertisement "
560 			   "Protocol element ID %u in response from " MACSTR,
561 			   *pos, MAC2STR(sa));
562 		return 0;
563 	}
564 
565 	adv_proto = pos;
566 	pos += 2 + pos[1];
567 
568 	/* Query Response Length */
569 	if (pos + 2 > data + len) {
570 		wpa_printf(MSG_DEBUG, "GAS: No room for GAS Response Length");
571 		return 0;
572 	}
573 	resp_len = WPA_GET_LE16(pos);
574 	pos += 2;
575 
576 	left = data + len - pos;
577 	if (resp_len > left) {
578 		wpa_printf(MSG_DEBUG, "GAS: Truncated Query Response in "
579 			   "response from " MACSTR, MAC2STR(sa));
580 		return 0;
581 	}
582 
583 	if (resp_len < left) {
584 		wpa_printf(MSG_DEBUG, "GAS: Ignore %u octets of extra data "
585 			   "after Query Response from " MACSTR,
586 			   left - resp_len, MAC2STR(sa));
587 	}
588 
589 	if (action == WLAN_PA_GAS_COMEBACK_RESP)
590 		gas_query_rx_comeback(gas, query, adv_proto, pos, resp_len,
591 				      frag_id, more_frags, comeback_delay);
592 	else
593 		gas_query_rx_initial(gas, query, adv_proto, pos, resp_len,
594 				     comeback_delay);
595 
596 	return 0;
597 }
598 
599 
600 static void gas_query_timeout(void *eloop_data, void *user_ctx)
601 {
602 	struct gas_query_ap *gas = eloop_data;
603 	struct gas_query_pending *query = user_ctx;
604 
605 	wpa_printf(MSG_DEBUG, "GAS: No response received for query to " MACSTR
606 		   " dialog token %u",
607 		   MAC2STR(query->addr), query->dialog_token);
608 	gas_query_done(gas, query, GAS_QUERY_AP_TIMEOUT);
609 }
610 
611 
612 static int gas_query_dialog_token_available(struct gas_query_ap *gas,
613 					    const u8 *dst, u8 dialog_token)
614 {
615 	struct gas_query_pending *q;
616 	dl_list_for_each(q, &gas->pending, struct gas_query_pending, list) {
617 		if (os_memcmp(dst, q->addr, ETH_ALEN) == 0 &&
618 		    dialog_token == q->dialog_token)
619 			return 0;
620 	}
621 
622 	return 1;
623 }
624 
625 
626 static void gas_query_tx_initial_req(struct gas_query_ap *gas,
627 				     struct gas_query_pending *query)
628 {
629 	if (gas_query_tx(gas, query, query->req,
630 			 GAS_QUERY_WAIT_TIME_INITIAL) < 0) {
631 		wpa_printf(MSG_DEBUG, "GAS: Failed to send Action frame to "
632 			   MACSTR, MAC2STR(query->addr));
633 		gas_query_done(gas, query, GAS_QUERY_AP_INTERNAL_ERROR);
634 		return;
635 	}
636 	gas->current = query;
637 
638 	wpa_printf(MSG_DEBUG, "GAS: Starting query timeout for dialog token %u",
639 		   query->dialog_token);
640 	eloop_register_timeout(GAS_QUERY_TIMEOUT_PERIOD, 0,
641 			       gas_query_timeout, gas, query);
642 }
643 
644 
645 static int gas_query_new_dialog_token(struct gas_query_ap *gas, const u8 *dst)
646 {
647 	static int next_start = 0;
648 	int dialog_token;
649 
650 	for (dialog_token = 0; dialog_token < 256; dialog_token++) {
651 		if (gas_query_dialog_token_available(
652 			    gas, dst, (next_start + dialog_token) % 256))
653 			break;
654 	}
655 	if (dialog_token == 256)
656 		return -1; /* Too many pending queries */
657 	dialog_token = (next_start + dialog_token) % 256;
658 	next_start = (dialog_token + 1) % 256;
659 	return dialog_token;
660 }
661 
662 
663 /**
664  * gas_query_ap_req - Request a GAS query
665  * @gas: GAS query data from gas_query_init()
666  * @dst: Destination MAC address for the query
667  * @freq: Frequency (in MHz) for the channel on which to send the query
668  * @req: GAS query payload (to be freed by gas_query module in case of success
669  *	return)
670  * @cb: Callback function for reporting GAS query result and response
671  * @ctx: Context pointer to use with the @cb call
672  * Returns: dialog token (>= 0) on success or -1 on failure
673  */
674 int gas_query_ap_req(struct gas_query_ap *gas, const u8 *dst, int freq,
675 		     struct wpabuf *req,
676 		     void (*cb)(void *ctx, const u8 *dst, u8 dialog_token,
677 				enum gas_query_ap_result result,
678 				const struct wpabuf *adv_proto,
679 				const struct wpabuf *resp, u16 status_code),
680 		     void *ctx)
681 {
682 	struct gas_query_pending *query;
683 	int dialog_token;
684 
685 	if (!gas || wpabuf_len(req) < 3)
686 		return -1;
687 
688 	dialog_token = gas_query_new_dialog_token(gas, dst);
689 	if (dialog_token < 0)
690 		return -1;
691 
692 	query = os_zalloc(sizeof(*query));
693 	if (query == NULL)
694 		return -1;
695 
696 	query->gas = gas;
697 	os_memcpy(query->addr, dst, ETH_ALEN);
698 	query->dialog_token = dialog_token;
699 	query->freq = freq;
700 	query->cb = cb;
701 	query->ctx = ctx;
702 	query->req = req;
703 	dl_list_add(&gas->pending, &query->list);
704 
705 	*(wpabuf_mhead_u8(req) + 2) = dialog_token;
706 
707 	wpa_msg(gas->msg_ctx, MSG_INFO, GAS_QUERY_START "addr=" MACSTR
708 		" dialog_token=%u freq=%d",
709 		MAC2STR(query->addr), query->dialog_token, query->freq);
710 
711 	gas_query_tx_initial_req(gas, query);
712 
713 	return dialog_token;
714 }
715