xref: /freebsd/contrib/wpa/wpa_supplicant/op_classes.c (revision 71e72c9e91c4b8007a4292e09669e8b549c29e97)
1 /*
2  * Operating classes
3  * Copyright(c) 2015 Intel Deutschland GmbH
4  * Contact Information:
5  * Intel Linux Wireless <ilw@linux.intel.com>
6  * Intel Corporation, 5200 N.E. Elam Young Parkway, Hillsboro, OR 97124-6497
7  *
8  * This software may be distributed under the terms of the BSD license.
9  * See README for more details.
10  */
11 
12 #include "utils/includes.h"
13 
14 #include "utils/common.h"
15 #include "common/ieee802_11_common.h"
16 #include "wpa_supplicant_i.h"
17 #include "bss.h"
18 #include "config.h"
19 
20 
allow_channel(struct hostapd_hw_modes * mode,u8 op_class,u8 chan,unsigned int * flags)21 static enum chan_allowed allow_channel(struct hostapd_hw_modes *mode,
22 				       u8 op_class, u8 chan,
23 				       unsigned int *flags)
24 {
25 	int i;
26 	bool is_6ghz = is_6ghz_op_class(op_class);
27 
28 	for (i = 0; i < mode->num_channels; i++) {
29 		bool chan_is_6ghz;
30 
31 		chan_is_6ghz = is_6ghz_freq(mode->channels[i].freq);
32 		if (is_6ghz == chan_is_6ghz && mode->channels[i].chan == chan)
33 			break;
34 	}
35 
36 	if (i == mode->num_channels ||
37 	    (mode->channels[i].flag & HOSTAPD_CHAN_DISABLED))
38 		return NOT_ALLOWED;
39 
40 	if (flags)
41 		*flags = mode->channels[i].flag;
42 
43 	if (mode->channels[i].flag & HOSTAPD_CHAN_NO_IR)
44 		return NO_IR;
45 
46 	return ALLOWED;
47 }
48 
49 
get_center_80mhz(struct hostapd_hw_modes * mode,u8 channel,const u8 * center_channels,size_t num_chan)50 static int get_center_80mhz(struct hostapd_hw_modes *mode, u8 channel,
51 			    const u8 *center_channels, size_t num_chan)
52 {
53 	size_t i;
54 
55 	if (mode->mode != HOSTAPD_MODE_IEEE80211A)
56 		return 0;
57 
58 	for (i = 0; i < num_chan; i++) {
59 		/*
60 		 * In 80 MHz, the bandwidth "spans" 12 channels (e.g., 36-48),
61 		 * so the center channel is 6 channels away from the start/end.
62 		 */
63 		if (channel >= center_channels[i] - 6 &&
64 		    channel <= center_channels[i] + 6)
65 			return center_channels[i];
66 	}
67 
68 	return 0;
69 }
70 
71 
verify_80mhz(struct hostapd_hw_modes * mode,u8 op_class,u8 channel)72 static enum chan_allowed verify_80mhz(struct hostapd_hw_modes *mode,
73 				      u8 op_class, u8 channel)
74 {
75 	u8 center_chan;
76 	unsigned int i;
77 	unsigned int no_ir = 0;
78 	const u8 *center_channels;
79 	size_t num_chan;
80 	const u8 center_channels_5ghz[] = { 42, 58, 106, 122, 138, 155, 171 };
81 	const u8 center_channels_6ghz[] = { 7, 23, 39, 55, 71, 87, 103, 119,
82 					    135, 151, 167, 183, 199, 215 };
83 
84 	if (is_6ghz_op_class(op_class)) {
85 		center_channels = center_channels_6ghz;
86 		num_chan = ARRAY_SIZE(center_channels_6ghz);
87 	} else {
88 		center_channels = center_channels_5ghz;
89 		num_chan = ARRAY_SIZE(center_channels_5ghz);
90 	}
91 
92 	center_chan = get_center_80mhz(mode, channel, center_channels,
93 				       num_chan);
94 	if (!center_chan)
95 		return NOT_ALLOWED;
96 
97 	/* check all the channels are available */
98 	for (i = 0; i < 4; i++) {
99 		unsigned int flags;
100 		u8 adj_chan = center_chan - 6 + i * 4;
101 
102 		if (allow_channel(mode, op_class, adj_chan, &flags) ==
103 		    NOT_ALLOWED)
104 			return NOT_ALLOWED;
105 
106 		if (!(flags & HOSTAPD_CHAN_VHT_80MHZ_SUBCHANNEL))
107 			return NOT_ALLOWED;
108 
109 		if (flags & HOSTAPD_CHAN_NO_IR)
110 			no_ir = 1;
111 	}
112 
113 	if (no_ir)
114 		return NO_IR;
115 
116 	return ALLOWED;
117 }
118 
119 
get_center_160mhz(struct hostapd_hw_modes * mode,u8 channel,const u8 * center_channels,size_t num_chan)120 static int get_center_160mhz(struct hostapd_hw_modes *mode, u8 channel,
121 			     const u8 *center_channels, size_t num_chan)
122 {
123 	unsigned int i;
124 
125 	if (mode->mode != HOSTAPD_MODE_IEEE80211A)
126 		return 0;
127 
128 	for (i = 0; i < num_chan; i++) {
129 		/*
130 		 * In 160 MHz, the bandwidth "spans" 28 channels (e.g., 36-64),
131 		 * so the center channel is 14 channels away from the start/end.
132 		 */
133 		if (channel >= center_channels[i] - 14 &&
134 		    channel <= center_channels[i] + 14)
135 			return center_channels[i];
136 	}
137 
138 	return 0;
139 }
140 
141 
verify_160mhz(struct hostapd_hw_modes * mode,u8 op_class,u8 channel)142 static enum chan_allowed verify_160mhz(struct hostapd_hw_modes *mode,
143 				       u8 op_class, u8 channel)
144 {
145 	u8 center_chan;
146 	unsigned int i;
147 	unsigned int no_ir = 0;
148 	const u8 *center_channels;
149 	size_t num_chan;
150 	const u8 center_channels_5ghz[] = { 50, 114, 163 };
151 	const u8 center_channels_6ghz[] = { 15, 47, 79, 111, 143, 175, 207 };
152 
153 	if (is_6ghz_op_class(op_class)) {
154 		center_channels = center_channels_6ghz;
155 		num_chan = ARRAY_SIZE(center_channels_6ghz);
156 	} else {
157 		center_channels = center_channels_5ghz;
158 		num_chan = ARRAY_SIZE(center_channels_5ghz);
159 	}
160 
161 	center_chan = get_center_160mhz(mode, channel, center_channels,
162 					num_chan);
163 	if (!center_chan)
164 		return NOT_ALLOWED;
165 
166 	/* Check all the channels are available */
167 	for (i = 0; i < 8; i++) {
168 		unsigned int flags;
169 		u8 adj_chan = center_chan - 14 + i * 4;
170 
171 		if (allow_channel(mode, op_class, adj_chan, &flags) ==
172 		    NOT_ALLOWED)
173 			return NOT_ALLOWED;
174 
175 		if (!(flags & HOSTAPD_CHAN_VHT_80MHZ_SUBCHANNEL) ||
176 		    (!(flags & HOSTAPD_CHAN_VHT_160MHZ_SUBCHANNEL) &&
177 		     !(flags & HOSTAPD_CHAN_AUTO_BW)))
178 			return NOT_ALLOWED;
179 
180 		if (flags & HOSTAPD_CHAN_NO_IR)
181 			no_ir = 1;
182 	}
183 
184 	if (no_ir)
185 		return NO_IR;
186 
187 	return ALLOWED;
188 }
189 
190 
get_center_320mhz(struct hostapd_hw_modes * mode,u8 channel,const u8 * center_channels,size_t num_chan)191 static int get_center_320mhz(struct hostapd_hw_modes *mode, u8 channel,
192 			     const u8 *center_channels, size_t num_chan)
193 {
194 	unsigned int i;
195 
196 	if (mode->mode != HOSTAPD_MODE_IEEE80211A || !mode->is_6ghz)
197 		return 0;
198 
199 	for (i = 0; i < num_chan; i++) {
200 		/*
201 		* In 320 MHz, the bandwidth "spans" 60 channels (e.g., 65-125),
202 		* so the center channel is 30 channels away from the start/end.
203 		*/
204 		if (channel >= center_channels[i] - 30 &&
205 		    channel <= center_channels[i] + 30)
206 			return center_channels[i];
207 	}
208 
209 	return 0;
210 }
211 
212 
verify_320mhz(struct hostapd_hw_modes * mode,u8 op_class,u8 channel)213 static enum chan_allowed verify_320mhz(struct hostapd_hw_modes *mode,
214 				       u8 op_class, u8 channel)
215 {
216 	u8 center_chan;
217 	unsigned int i;
218 	bool no_ir = false;
219 	const u8 *center_channels;
220 	size_t num_chan;
221 	const u8 center_channels_6ghz[] = { 31, 63, 95, 127, 159, 191 };
222 
223 	center_channels = center_channels_6ghz;
224 	num_chan = ARRAY_SIZE(center_channels_6ghz);
225 
226 	center_chan = get_center_320mhz(mode, channel, center_channels,
227 					num_chan);
228 	if (!center_chan)
229 		return NOT_ALLOWED;
230 
231 	/* Check all the channels are available */
232 	for (i = 0; i < 16; i++) {
233 		unsigned int flags;
234 		u8 adj_chan = center_chan - 30 + i * 4;
235 
236 		if (allow_channel(mode, op_class, adj_chan, &flags) ==
237 		    NOT_ALLOWED)
238 			return NOT_ALLOWED;
239 
240 		if (!(flags & HOSTAPD_CHAN_EHT_320MHZ_SUBCHANNEL))
241 			return NOT_ALLOWED;
242 
243 		if (flags & HOSTAPD_CHAN_NO_IR)
244 			no_ir = true;
245 	}
246 
247 	if (no_ir)
248 		return NO_IR;
249 
250 	return ALLOWED;
251 }
252 
253 
verify_channel(struct hostapd_hw_modes * mode,u8 op_class,u8 channel,u8 bw)254 enum chan_allowed verify_channel(struct hostapd_hw_modes *mode, u8 op_class,
255 				 u8 channel, u8 bw)
256 {
257 	unsigned int flag = 0;
258 	enum chan_allowed res, res2;
259 
260 	res2 = res = allow_channel(mode, op_class, channel, &flag);
261 	if (bw == BW40MINUS || (bw == BW40 && (((channel - 1) / 4) % 2))) {
262 		if (!(flag & HOSTAPD_CHAN_HT40MINUS))
263 			return NOT_ALLOWED;
264 		res2 = allow_channel(mode, op_class, channel - 4, NULL);
265 	} else if (bw == BW40PLUS) {
266 		if (!(flag & HOSTAPD_CHAN_HT40PLUS))
267 			return NOT_ALLOWED;
268 		res2 = allow_channel(mode, op_class, channel + 4, NULL);
269 	} else if (is_6ghz_op_class(op_class) && bw == BW40) {
270 		if (get_6ghz_sec_channel(channel) < 0)
271 			res2 = allow_channel(mode, op_class, channel - 4, NULL);
272 		else
273 			res2 = allow_channel(mode, op_class, channel + 4, NULL);
274 	} else if (bw == BW80) {
275 		/*
276 		 * channel is a center channel and as such, not necessarily a
277 		 * valid 20 MHz channels. Override earlier allow_channel()
278 		 * result and use only the 80 MHz specific version.
279 		 */
280 		res2 = res = verify_80mhz(mode, op_class, channel);
281 	} else if (bw == BW160) {
282 		/*
283 		 * channel is a center channel and as such, not necessarily a
284 		 * valid 20 MHz channels. Override earlier allow_channel()
285 		 * result and use only the 160 MHz specific version.
286 		 */
287 		res2 = res = verify_160mhz(mode, op_class, channel);
288 	} else if (bw == BW80P80) {
289 		/*
290 		 * channel is a center channel and as such, not necessarily a
291 		 * valid 20 MHz channels. Override earlier allow_channel()
292 		 * result and use only the 80 MHz specific version.
293 		 */
294 		res2 = res = verify_80mhz(mode, op_class, channel);
295 	} else if (bw == BW320) {
296 		/*
297 		 * channel is a center channel and as such, not necessarily a
298 		 * valid 20 MHz channels. Override earlier allow_channel()
299 		 * result and use only the 320 MHz specific version.
300 		 */
301 		res2= res = verify_320mhz(mode, op_class, channel);
302 	}
303 
304 	if (res == NOT_ALLOWED || res2 == NOT_ALLOWED)
305 		return NOT_ALLOWED;
306 
307 	if (res == NO_IR || res2 == NO_IR)
308 		return NO_IR;
309 
310 	return ALLOWED;
311 }
312 
313 
wpas_op_class_supported(struct wpa_supplicant * wpa_s,struct wpa_ssid * ssid,const struct oper_class_map * op_class)314 static int wpas_op_class_supported(struct wpa_supplicant *wpa_s,
315 				   struct wpa_ssid *ssid,
316 				   const struct oper_class_map *op_class)
317 {
318 	int chan;
319 	size_t i;
320 	struct hostapd_hw_modes *mode;
321 	int found;
322 	int z;
323 	int freq2 = 0;
324 	int freq5 = 0;
325 	bool freq6 = false;
326 
327 	mode = get_mode(wpa_s->hw.modes, wpa_s->hw.num_modes, op_class->mode,
328 			is_6ghz_op_class(op_class->op_class));
329 	if (!mode)
330 		return 0;
331 
332 	/* If we are configured to disable certain things, take that into
333 	 * account here. */
334 	if (ssid && ssid->freq_list && ssid->freq_list[0]) {
335 		for (z = 0; ; z++) {
336 			int f = ssid->freq_list[z];
337 
338 			if (f == 0)
339 				break; /* end of list */
340 			if (is_6ghz_freq(f))
341 				freq6 = true;
342 			else if (f > 4000 && f < 6000)
343 				freq5 = 1;
344 			else if (f > 2400 && f < 2500)
345 				freq2 = 1;
346 		}
347 	} else {
348 		/* No frequencies specified, can use anything hardware supports.
349 		 */
350 		freq2 = freq5 = 1;
351 		freq6 = true;
352 	}
353 
354 	if (is_6ghz_op_class(op_class->op_class) && !freq6)
355 		return 0;
356 	if (op_class->op_class >= 115 && op_class->op_class <= 130 && !freq5)
357 		return 0;
358 	if (op_class->op_class >= 81 && op_class->op_class <= 84 && !freq2)
359 		return 0;
360 
361 #ifdef CONFIG_HT_OVERRIDES
362 	if (ssid && ssid->disable_ht) {
363 		switch (op_class->op_class) {
364 		case 83:
365 		case 84:
366 		case 104:
367 		case 105:
368 		case 116:
369 		case 117:
370 		case 119:
371 		case 120:
372 		case 122:
373 		case 123:
374 		case 126:
375 		case 127:
376 		case 128:
377 		case 129:
378 		case 130:
379 			/* Disable >= 40 MHz channels if HT is disabled */
380 			return 0;
381 		}
382 	}
383 #endif /* CONFIG_HT_OVERRIDES */
384 
385 #ifdef CONFIG_VHT_OVERRIDES
386 	if (ssid && ssid->disable_vht) {
387 		if (op_class->op_class >= 128 && op_class->op_class <= 130) {
388 			/* Disable >= 80 MHz channels if VHT is disabled */
389 			return 0;
390 		}
391 	}
392 #endif /* CONFIG_VHT_OVERRIDES */
393 
394 	if (op_class->op_class == 128) {
395 		u8 channels[] = { 42, 58, 106, 122, 138, 155, 171 };
396 
397 		for (i = 0; i < ARRAY_SIZE(channels); i++) {
398 			if (verify_channel(mode, op_class->op_class,
399 					   channels[i], op_class->bw) !=
400 			    NOT_ALLOWED)
401 				return 1;
402 		}
403 
404 		return 0;
405 	}
406 
407 	if (op_class->op_class == 129) {
408 		/* Check if either 160 MHz channels is allowed */
409 		return verify_channel(mode, op_class->op_class, 50,
410 				      op_class->bw) != NOT_ALLOWED ||
411 			verify_channel(mode, op_class->op_class, 114,
412 				       op_class->bw) != NOT_ALLOWED ||
413 			verify_channel(mode, op_class->op_class, 163,
414 				       op_class->bw) != NOT_ALLOWED;
415 	}
416 
417 	if (op_class->op_class == 130) {
418 		/* Need at least two non-contiguous 80 MHz segments */
419 		found = 0;
420 
421 		if (verify_channel(mode, op_class->op_class, 42,
422 				   op_class->bw) != NOT_ALLOWED ||
423 		    verify_channel(mode, op_class->op_class, 58,
424 				   op_class->bw) != NOT_ALLOWED)
425 			found++;
426 		if (verify_channel(mode, op_class->op_class, 106,
427 				   op_class->bw) != NOT_ALLOWED ||
428 		    verify_channel(mode, op_class->op_class, 122,
429 				   op_class->bw) != NOT_ALLOWED ||
430 		    verify_channel(mode, op_class->op_class, 138,
431 				   op_class->bw) != NOT_ALLOWED ||
432 		    verify_channel(mode, op_class->op_class, 155,
433 				   op_class->bw) != NOT_ALLOWED ||
434 		    verify_channel(mode, op_class->op_class, 171,
435 				   op_class->bw) != NOT_ALLOWED)
436 			found++;
437 		if (verify_channel(mode, op_class->op_class, 106,
438 				   op_class->bw) != NOT_ALLOWED &&
439 		    verify_channel(mode, op_class->op_class, 138,
440 				   op_class->bw) != NOT_ALLOWED)
441 			found++;
442 		if (verify_channel(mode, op_class->op_class, 122,
443 				   op_class->bw) != NOT_ALLOWED &&
444 		    verify_channel(mode, op_class->op_class, 155,
445 				   op_class->bw) != NOT_ALLOWED)
446 			found++;
447 		if (verify_channel(mode, op_class->op_class, 138,
448 				   op_class->bw) != NOT_ALLOWED &&
449 		    verify_channel(mode, op_class->op_class, 171,
450 				   op_class->bw) != NOT_ALLOWED)
451 			found++;
452 
453 		if (found >= 2)
454 			return 1;
455 
456 		return 0;
457 	}
458 
459 	if (op_class->op_class == 135) {
460 		/* Need at least two 80 MHz segments which do not fall under the
461 		 * same 160 MHz segment to support 80+80 in 6 GHz.
462 		 */
463 		int first_seg = 0;
464 		int curr_seg = 0;
465 
466 		for (chan = op_class->min_chan; chan <= op_class->max_chan;
467 		     chan += op_class->inc) {
468 			curr_seg++;
469 			if (verify_channel(mode, op_class->op_class, chan,
470 					   op_class->bw) != NOT_ALLOWED) {
471 				if (!first_seg) {
472 					first_seg = curr_seg;
473 					continue;
474 				}
475 
476 				/* Supported if at least two non-consecutive 80
477 				 * MHz segments allowed.
478 				 */
479 				if ((curr_seg - first_seg) > 1)
480 					return 1;
481 
482 				/* Supported even if the 80 MHz segments are
483 				 * consecutive when they do not fall under the
484 				 * same 160 MHz segment.
485 				 */
486 				if ((first_seg % 2) == 0)
487 					return 1;
488 			}
489 		}
490 
491 		return 0;
492 	}
493 
494 	found = 0;
495 	for (chan = op_class->min_chan; chan <= op_class->max_chan;
496 	     chan += op_class->inc) {
497 		if (verify_channel(mode, op_class->op_class, chan,
498 				   op_class->bw) != NOT_ALLOWED) {
499 			found = 1;
500 			break;
501 		}
502 	}
503 
504 	return found;
505 }
506 
507 
wpas_sta_secondary_channel_offset(struct wpa_bss * bss,u8 * current,u8 * channel)508 static int wpas_sta_secondary_channel_offset(struct wpa_bss *bss, u8 *current,
509 					     u8 *channel)
510 {
511 
512 	const u8 *ies;
513 	u8 phy_type;
514 	size_t ies_len;
515 
516 	if (!bss)
517 		return -1;
518 	ies = wpa_bss_ie_ptr(bss);
519 	ies_len = bss->ie_len ? bss->ie_len : bss->beacon_ie_len;
520 	return wpas_get_op_chan_phy(bss->freq, ies, ies_len, current,
521 				    channel, &phy_type);
522 }
523 
524 
wpas_supp_op_class_ie(struct wpa_supplicant * wpa_s,struct wpa_ssid * ssid,struct wpa_bss * bss,u8 * pos,size_t len)525 size_t wpas_supp_op_class_ie(struct wpa_supplicant *wpa_s,
526 			     struct wpa_ssid *ssid,
527 			     struct wpa_bss *bss, u8 *pos, size_t len)
528 {
529 	struct wpabuf *buf;
530 	u8 op, current, chan;
531 	u8 *ie_len;
532 	size_t res;
533 	bool op128 = false, op130 = false, op133 = false, op135 = false;
534 	bool disable_op_classes_80_80_mhz = wpa_s->conf ?
535 		wpa_s->conf->disable_op_classes_80_80_mhz : false;
536 
537 	/*
538 	 * Determine the current operating class correct mode based on
539 	 * advertised BSS capabilities, if available. Fall back to a less
540 	 * accurate guess based on frequency if the needed IEs are not available
541 	 * or used.
542 	 */
543 	if (wpas_sta_secondary_channel_offset(bss, &current, &chan) < 0 &&
544 	    ieee80211_freq_to_channel_ext(bss->freq, 0,
545 					  CONF_OPER_CHWIDTH_USE_HT, &current,
546 					  &chan) == NUM_HOSTAPD_MODES)
547 		return 0;
548 
549 	/*
550 	 * Need 3 bytes for EID, length, and current operating class, plus
551 	 * 1 byte for every other supported operating class.
552 	 */
553 	buf = wpabuf_alloc(global_op_class_size + 3);
554 	if (!buf)
555 		return 0;
556 
557 	wpabuf_put_u8(buf, WLAN_EID_SUPPORTED_OPERATING_CLASSES);
558 	/* Will set the length later, putting a placeholder */
559 	ie_len = wpabuf_put(buf, 1);
560 	wpabuf_put_u8(buf, current);
561 
562 	for (op = 0; global_op_class[op].op_class; op++) {
563 		bool supp;
564 		u8 op_class = global_op_class[op].op_class;
565 
566 		supp = wpas_op_class_supported(wpa_s, ssid,
567 					       &global_op_class[op]);
568 		if (!supp)
569 			continue;
570 		switch (op_class) {
571 		case 128:
572 			op128 = true;
573 			break;
574 		case 130:
575 			op130 = true;
576 			break;
577 		case 133:
578 			op133 = true;
579 			break;
580 		case 135:
581 			op135 = true;
582 			break;
583 		}
584 		if (is_80plus_op_class(op_class))
585 			continue;
586 
587 		/* Add a 1-octet operating class to the Operating Class field */
588 		wpabuf_put_u8(buf, global_op_class[op].op_class);
589 	}
590 
591 	/* Add the 2-octet operating classes (i.e., 80+80 MHz cases), if any */
592 	if (!disable_op_classes_80_80_mhz &&
593 	    ((op128 && op130) || (op133 && op135))) {
594 		/* Operating Class Duple Sequence field */
595 
596 		/* Zero Delimiter */
597 		wpabuf_put_u8(buf, 0);
598 
599 		/* Operating Class Duple List */
600 		if (op128 && op130) {
601 			wpabuf_put_u8(buf, 130);
602 			wpabuf_put_u8(buf, 128);
603 		}
604 		if (op133 && op135) {
605 			wpabuf_put_u8(buf, 135);
606 			wpabuf_put_u8(buf, 133);
607 		}
608 	}
609 
610 	*ie_len = wpabuf_len(buf) - 2;
611 	if (*ie_len < 2) {
612 		wpa_printf(MSG_DEBUG,
613 			   "No supported operating classes IE to add");
614 		res = 0;
615 	} else if (wpabuf_len(buf) > len) {
616 		wpa_printf(MSG_ERROR,
617 			   "Supported operating classes IE exceeds maximum buffer length");
618 		res = 0;
619 	} else {
620 		os_memcpy(pos, wpabuf_head(buf), wpabuf_len(buf));
621 		res = wpabuf_len(buf);
622 		wpa_hexdump_buf(MSG_DEBUG,
623 				"Added supported operating classes IE", buf);
624 	}
625 
626 	wpabuf_free(buf);
627 	return res;
628 }
629 
630 
wpas_supp_op_classes(struct wpa_supplicant * wpa_s)631 int * wpas_supp_op_classes(struct wpa_supplicant *wpa_s)
632 {
633 	int op;
634 	unsigned int pos, max_num = 0;
635 	int *classes;
636 
637 	for (op = 0; global_op_class[op].op_class; op++)
638 		max_num++;
639 	classes = os_zalloc((max_num + 1) * sizeof(int));
640 	if (!classes)
641 		return NULL;
642 
643 	for (op = 0, pos = 0; global_op_class[op].op_class; op++) {
644 		if (wpas_op_class_supported(wpa_s, NULL, &global_op_class[op]))
645 			classes[pos++] = global_op_class[op].op_class;
646 	}
647 
648 	return classes;
649 }
650