1 /* Copyright (C) 2009-2016  B.A.T.M.A.N. contributors:
2  *
3  * Marek Lindner
4  *
5  * This program is free software; you can redistribute it and/or
6  * modify it under the terms of version 2 of the GNU General Public
7  * License as published by the Free Software Foundation.
8  *
9  * This program is distributed in the hope that it will be useful, but
10  * WITHOUT ANY WARRANTY; without even the implied warranty of
11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12  * General Public License for more details.
13  *
14  * You should have received a copy of the GNU General Public License
15  * along with this program; if not, see <http://www.gnu.org/licenses/>.
16  */
17 
18 #include "gateway_client.h"
19 #include "main.h"
20 
21 #include <linux/atomic.h>
22 #include <linux/byteorder/generic.h>
23 #include <linux/etherdevice.h>
24 #include <linux/fs.h>
25 #include <linux/if_ether.h>
26 #include <linux/if_vlan.h>
27 #include <linux/in.h>
28 #include <linux/ip.h>
29 #include <linux/ipv6.h>
30 #include <linux/kernel.h>
31 #include <linux/kref.h>
32 #include <linux/list.h>
33 #include <linux/netdevice.h>
34 #include <linux/rculist.h>
35 #include <linux/rcupdate.h>
36 #include <linux/seq_file.h>
37 #include <linux/skbuff.h>
38 #include <linux/slab.h>
39 #include <linux/spinlock.h>
40 #include <linux/stddef.h>
41 #include <linux/udp.h>
42 
43 #include "gateway_common.h"
44 #include "hard-interface.h"
45 #include "originator.h"
46 #include "packet.h"
47 #include "routing.h"
48 #include "sysfs.h"
49 #include "translation-table.h"
50 
51 /* These are the offsets of the "hw type" and "hw address length" in the dhcp
52  * packet starting at the beginning of the dhcp header
53  */
54 #define BATADV_DHCP_HTYPE_OFFSET	1
55 #define BATADV_DHCP_HLEN_OFFSET		2
56 /* Value of htype representing Ethernet */
57 #define BATADV_DHCP_HTYPE_ETHERNET	0x01
58 /* This is the offset of the "chaddr" field in the dhcp packet starting at the
59  * beginning of the dhcp header
60  */
61 #define BATADV_DHCP_CHADDR_OFFSET	28
62 
63 /**
64  * batadv_gw_node_release - release gw_node from lists and queue for free after
65  *  rcu grace period
66  * @ref: kref pointer of the gw_node
67  */
68 static void batadv_gw_node_release(struct kref *ref)
69 {
70 	struct batadv_gw_node *gw_node;
71 
72 	gw_node = container_of(ref, struct batadv_gw_node, refcount);
73 
74 	batadv_orig_node_put(gw_node->orig_node);
75 	kfree_rcu(gw_node, rcu);
76 }
77 
78 /**
79  * batadv_gw_node_put - decrement the gw_node refcounter and possibly release it
80  * @gw_node: gateway node to free
81  */
82 static void batadv_gw_node_put(struct batadv_gw_node *gw_node)
83 {
84 	kref_put(&gw_node->refcount, batadv_gw_node_release);
85 }
86 
87 static struct batadv_gw_node *
88 batadv_gw_get_selected_gw_node(struct batadv_priv *bat_priv)
89 {
90 	struct batadv_gw_node *gw_node;
91 
92 	rcu_read_lock();
93 	gw_node = rcu_dereference(bat_priv->gw.curr_gw);
94 	if (!gw_node)
95 		goto out;
96 
97 	if (!kref_get_unless_zero(&gw_node->refcount))
98 		gw_node = NULL;
99 
100 out:
101 	rcu_read_unlock();
102 	return gw_node;
103 }
104 
105 struct batadv_orig_node *
106 batadv_gw_get_selected_orig(struct batadv_priv *bat_priv)
107 {
108 	struct batadv_gw_node *gw_node;
109 	struct batadv_orig_node *orig_node = NULL;
110 
111 	gw_node = batadv_gw_get_selected_gw_node(bat_priv);
112 	if (!gw_node)
113 		goto out;
114 
115 	rcu_read_lock();
116 	orig_node = gw_node->orig_node;
117 	if (!orig_node)
118 		goto unlock;
119 
120 	if (!kref_get_unless_zero(&orig_node->refcount))
121 		orig_node = NULL;
122 
123 unlock:
124 	rcu_read_unlock();
125 out:
126 	if (gw_node)
127 		batadv_gw_node_put(gw_node);
128 	return orig_node;
129 }
130 
131 static void batadv_gw_select(struct batadv_priv *bat_priv,
132 			     struct batadv_gw_node *new_gw_node)
133 {
134 	struct batadv_gw_node *curr_gw_node;
135 
136 	spin_lock_bh(&bat_priv->gw.list_lock);
137 
138 	if (new_gw_node && !kref_get_unless_zero(&new_gw_node->refcount))
139 		new_gw_node = NULL;
140 
141 	curr_gw_node = rcu_dereference_protected(bat_priv->gw.curr_gw, 1);
142 	rcu_assign_pointer(bat_priv->gw.curr_gw, new_gw_node);
143 
144 	if (curr_gw_node)
145 		batadv_gw_node_put(curr_gw_node);
146 
147 	spin_unlock_bh(&bat_priv->gw.list_lock);
148 }
149 
150 /**
151  * batadv_gw_reselect - force a gateway reselection
152  * @bat_priv: the bat priv with all the soft interface information
153  *
154  * Set a flag to remind the GW component to perform a new gateway reselection.
155  * However this function does not ensure that the current gateway is going to be
156  * deselected. The reselection mechanism may elect the same gateway once again.
157  *
158  * This means that invoking batadv_gw_reselect() does not guarantee a gateway
159  * change and therefore a uevent is not necessarily expected.
160  */
161 void batadv_gw_reselect(struct batadv_priv *bat_priv)
162 {
163 	atomic_set(&bat_priv->gw.reselect, 1);
164 }
165 
166 static struct batadv_gw_node *
167 batadv_gw_get_best_gw_node(struct batadv_priv *bat_priv)
168 {
169 	struct batadv_neigh_node *router;
170 	struct batadv_neigh_ifinfo *router_ifinfo;
171 	struct batadv_gw_node *gw_node, *curr_gw = NULL;
172 	u64 max_gw_factor = 0;
173 	u64 tmp_gw_factor = 0;
174 	u8 max_tq = 0;
175 	u8 tq_avg;
176 	struct batadv_orig_node *orig_node;
177 
178 	rcu_read_lock();
179 	hlist_for_each_entry_rcu(gw_node, &bat_priv->gw.list, list) {
180 		orig_node = gw_node->orig_node;
181 		router = batadv_orig_router_get(orig_node, BATADV_IF_DEFAULT);
182 		if (!router)
183 			continue;
184 
185 		router_ifinfo = batadv_neigh_ifinfo_get(router,
186 							BATADV_IF_DEFAULT);
187 		if (!router_ifinfo)
188 			goto next;
189 
190 		if (!kref_get_unless_zero(&gw_node->refcount))
191 			goto next;
192 
193 		tq_avg = router_ifinfo->bat_iv.tq_avg;
194 
195 		switch (atomic_read(&bat_priv->gw_sel_class)) {
196 		case 1: /* fast connection */
197 			tmp_gw_factor = tq_avg * tq_avg;
198 			tmp_gw_factor *= gw_node->bandwidth_down;
199 			tmp_gw_factor *= 100 * 100;
200 			tmp_gw_factor >>= 18;
201 
202 			if ((tmp_gw_factor > max_gw_factor) ||
203 			    ((tmp_gw_factor == max_gw_factor) &&
204 			     (tq_avg > max_tq))) {
205 				if (curr_gw)
206 					batadv_gw_node_put(curr_gw);
207 				curr_gw = gw_node;
208 				kref_get(&curr_gw->refcount);
209 			}
210 			break;
211 
212 		default: /* 2:  stable connection (use best statistic)
213 			  * 3:  fast-switch (use best statistic but change as
214 			  *     soon as a better gateway appears)
215 			  * XX: late-switch (use best statistic but change as
216 			  *     soon as a better gateway appears which has
217 			  *     $routing_class more tq points)
218 			  */
219 			if (tq_avg > max_tq) {
220 				if (curr_gw)
221 					batadv_gw_node_put(curr_gw);
222 				curr_gw = gw_node;
223 				kref_get(&curr_gw->refcount);
224 			}
225 			break;
226 		}
227 
228 		if (tq_avg > max_tq)
229 			max_tq = tq_avg;
230 
231 		if (tmp_gw_factor > max_gw_factor)
232 			max_gw_factor = tmp_gw_factor;
233 
234 		batadv_gw_node_put(gw_node);
235 
236 next:
237 		batadv_neigh_node_put(router);
238 		if (router_ifinfo)
239 			batadv_neigh_ifinfo_put(router_ifinfo);
240 	}
241 	rcu_read_unlock();
242 
243 	return curr_gw;
244 }
245 
246 /**
247  * batadv_gw_check_client_stop - check if client mode has been switched off
248  * @bat_priv: the bat priv with all the soft interface information
249  *
250  * This function assumes the caller has checked that the gw state *is actually
251  * changing*. This function is not supposed to be called when there is no state
252  * change.
253  */
254 void batadv_gw_check_client_stop(struct batadv_priv *bat_priv)
255 {
256 	struct batadv_gw_node *curr_gw;
257 
258 	if (atomic_read(&bat_priv->gw_mode) != BATADV_GW_MODE_CLIENT)
259 		return;
260 
261 	curr_gw = batadv_gw_get_selected_gw_node(bat_priv);
262 	if (!curr_gw)
263 		return;
264 
265 	/* deselect the current gateway so that next time that client mode is
266 	 * enabled a proper GW_ADD event can be sent
267 	 */
268 	batadv_gw_select(bat_priv, NULL);
269 
270 	/* if batman-adv is switching the gw client mode off and a gateway was
271 	 * already selected, send a DEL uevent
272 	 */
273 	batadv_throw_uevent(bat_priv, BATADV_UEV_GW, BATADV_UEV_DEL, NULL);
274 
275 	batadv_gw_node_put(curr_gw);
276 }
277 
278 void batadv_gw_election(struct batadv_priv *bat_priv)
279 {
280 	struct batadv_gw_node *curr_gw = NULL;
281 	struct batadv_gw_node *next_gw = NULL;
282 	struct batadv_neigh_node *router = NULL;
283 	struct batadv_neigh_ifinfo *router_ifinfo = NULL;
284 	char gw_addr[18] = { '\0' };
285 
286 	if (atomic_read(&bat_priv->gw_mode) != BATADV_GW_MODE_CLIENT)
287 		goto out;
288 
289 	curr_gw = batadv_gw_get_selected_gw_node(bat_priv);
290 
291 	if (!batadv_atomic_dec_not_zero(&bat_priv->gw.reselect) && curr_gw)
292 		goto out;
293 
294 	next_gw = batadv_gw_get_best_gw_node(bat_priv);
295 
296 	if (curr_gw == next_gw)
297 		goto out;
298 
299 	if (next_gw) {
300 		sprintf(gw_addr, "%pM", next_gw->orig_node->orig);
301 
302 		router = batadv_orig_router_get(next_gw->orig_node,
303 						BATADV_IF_DEFAULT);
304 		if (!router) {
305 			batadv_gw_reselect(bat_priv);
306 			goto out;
307 		}
308 
309 		router_ifinfo = batadv_neigh_ifinfo_get(router,
310 							BATADV_IF_DEFAULT);
311 		if (!router_ifinfo) {
312 			batadv_gw_reselect(bat_priv);
313 			goto out;
314 		}
315 	}
316 
317 	if ((curr_gw) && (!next_gw)) {
318 		batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
319 			   "Removing selected gateway - no gateway in range\n");
320 		batadv_throw_uevent(bat_priv, BATADV_UEV_GW, BATADV_UEV_DEL,
321 				    NULL);
322 	} else if ((!curr_gw) && (next_gw)) {
323 		batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
324 			   "Adding route to gateway %pM (bandwidth: %u.%u/%u.%u MBit, tq: %i)\n",
325 			   next_gw->orig_node->orig,
326 			   next_gw->bandwidth_down / 10,
327 			   next_gw->bandwidth_down % 10,
328 			   next_gw->bandwidth_up / 10,
329 			   next_gw->bandwidth_up % 10,
330 			   router_ifinfo->bat_iv.tq_avg);
331 		batadv_throw_uevent(bat_priv, BATADV_UEV_GW, BATADV_UEV_ADD,
332 				    gw_addr);
333 	} else {
334 		batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
335 			   "Changing route to gateway %pM (bandwidth: %u.%u/%u.%u MBit, tq: %i)\n",
336 			   next_gw->orig_node->orig,
337 			   next_gw->bandwidth_down / 10,
338 			   next_gw->bandwidth_down % 10,
339 			   next_gw->bandwidth_up / 10,
340 			   next_gw->bandwidth_up % 10,
341 			   router_ifinfo->bat_iv.tq_avg);
342 		batadv_throw_uevent(bat_priv, BATADV_UEV_GW, BATADV_UEV_CHANGE,
343 				    gw_addr);
344 	}
345 
346 	batadv_gw_select(bat_priv, next_gw);
347 
348 out:
349 	if (curr_gw)
350 		batadv_gw_node_put(curr_gw);
351 	if (next_gw)
352 		batadv_gw_node_put(next_gw);
353 	if (router)
354 		batadv_neigh_node_put(router);
355 	if (router_ifinfo)
356 		batadv_neigh_ifinfo_put(router_ifinfo);
357 }
358 
359 void batadv_gw_check_election(struct batadv_priv *bat_priv,
360 			      struct batadv_orig_node *orig_node)
361 {
362 	struct batadv_neigh_ifinfo *router_orig_tq = NULL;
363 	struct batadv_neigh_ifinfo *router_gw_tq = NULL;
364 	struct batadv_orig_node *curr_gw_orig;
365 	struct batadv_neigh_node *router_gw = NULL;
366 	struct batadv_neigh_node *router_orig = NULL;
367 	u8 gw_tq_avg, orig_tq_avg;
368 
369 	curr_gw_orig = batadv_gw_get_selected_orig(bat_priv);
370 	if (!curr_gw_orig)
371 		goto reselect;
372 
373 	router_gw = batadv_orig_router_get(curr_gw_orig, BATADV_IF_DEFAULT);
374 	if (!router_gw)
375 		goto reselect;
376 
377 	router_gw_tq = batadv_neigh_ifinfo_get(router_gw,
378 					       BATADV_IF_DEFAULT);
379 	if (!router_gw_tq)
380 		goto reselect;
381 
382 	/* this node already is the gateway */
383 	if (curr_gw_orig == orig_node)
384 		goto out;
385 
386 	router_orig = batadv_orig_router_get(orig_node, BATADV_IF_DEFAULT);
387 	if (!router_orig)
388 		goto out;
389 
390 	router_orig_tq = batadv_neigh_ifinfo_get(router_orig,
391 						 BATADV_IF_DEFAULT);
392 	if (!router_orig_tq)
393 		goto out;
394 
395 	gw_tq_avg = router_gw_tq->bat_iv.tq_avg;
396 	orig_tq_avg = router_orig_tq->bat_iv.tq_avg;
397 
398 	/* the TQ value has to be better */
399 	if (orig_tq_avg < gw_tq_avg)
400 		goto out;
401 
402 	/* if the routing class is greater than 3 the value tells us how much
403 	 * greater the TQ value of the new gateway must be
404 	 */
405 	if ((atomic_read(&bat_priv->gw_sel_class) > 3) &&
406 	    (orig_tq_avg - gw_tq_avg < atomic_read(&bat_priv->gw_sel_class)))
407 		goto out;
408 
409 	batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
410 		   "Restarting gateway selection: better gateway found (tq curr: %i, tq new: %i)\n",
411 		   gw_tq_avg, orig_tq_avg);
412 
413 reselect:
414 	batadv_gw_reselect(bat_priv);
415 out:
416 	if (curr_gw_orig)
417 		batadv_orig_node_put(curr_gw_orig);
418 	if (router_gw)
419 		batadv_neigh_node_put(router_gw);
420 	if (router_orig)
421 		batadv_neigh_node_put(router_orig);
422 	if (router_gw_tq)
423 		batadv_neigh_ifinfo_put(router_gw_tq);
424 	if (router_orig_tq)
425 		batadv_neigh_ifinfo_put(router_orig_tq);
426 }
427 
428 /**
429  * batadv_gw_node_add - add gateway node to list of available gateways
430  * @bat_priv: the bat priv with all the soft interface information
431  * @orig_node: originator announcing gateway capabilities
432  * @gateway: announced bandwidth information
433  */
434 static void batadv_gw_node_add(struct batadv_priv *bat_priv,
435 			       struct batadv_orig_node *orig_node,
436 			       struct batadv_tvlv_gateway_data *gateway)
437 {
438 	struct batadv_gw_node *gw_node;
439 
440 	if (gateway->bandwidth_down == 0)
441 		return;
442 
443 	if (!kref_get_unless_zero(&orig_node->refcount))
444 		return;
445 
446 	gw_node = kzalloc(sizeof(*gw_node), GFP_ATOMIC);
447 	if (!gw_node) {
448 		batadv_orig_node_put(orig_node);
449 		return;
450 	}
451 
452 	INIT_HLIST_NODE(&gw_node->list);
453 	gw_node->orig_node = orig_node;
454 	gw_node->bandwidth_down = ntohl(gateway->bandwidth_down);
455 	gw_node->bandwidth_up = ntohl(gateway->bandwidth_up);
456 	kref_init(&gw_node->refcount);
457 
458 	spin_lock_bh(&bat_priv->gw.list_lock);
459 	hlist_add_head_rcu(&gw_node->list, &bat_priv->gw.list);
460 	spin_unlock_bh(&bat_priv->gw.list_lock);
461 
462 	batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
463 		   "Found new gateway %pM -> gw bandwidth: %u.%u/%u.%u MBit\n",
464 		   orig_node->orig,
465 		   ntohl(gateway->bandwidth_down) / 10,
466 		   ntohl(gateway->bandwidth_down) % 10,
467 		   ntohl(gateway->bandwidth_up) / 10,
468 		   ntohl(gateway->bandwidth_up) % 10);
469 }
470 
471 /**
472  * batadv_gw_node_get - retrieve gateway node from list of available gateways
473  * @bat_priv: the bat priv with all the soft interface information
474  * @orig_node: originator announcing gateway capabilities
475  *
476  * Return: gateway node if found or NULL otherwise.
477  */
478 static struct batadv_gw_node *
479 batadv_gw_node_get(struct batadv_priv *bat_priv,
480 		   struct batadv_orig_node *orig_node)
481 {
482 	struct batadv_gw_node *gw_node_tmp, *gw_node = NULL;
483 
484 	rcu_read_lock();
485 	hlist_for_each_entry_rcu(gw_node_tmp, &bat_priv->gw.list, list) {
486 		if (gw_node_tmp->orig_node != orig_node)
487 			continue;
488 
489 		if (!kref_get_unless_zero(&gw_node_tmp->refcount))
490 			continue;
491 
492 		gw_node = gw_node_tmp;
493 		break;
494 	}
495 	rcu_read_unlock();
496 
497 	return gw_node;
498 }
499 
500 /**
501  * batadv_gw_node_update - update list of available gateways with changed
502  *  bandwidth information
503  * @bat_priv: the bat priv with all the soft interface information
504  * @orig_node: originator announcing gateway capabilities
505  * @gateway: announced bandwidth information
506  */
507 void batadv_gw_node_update(struct batadv_priv *bat_priv,
508 			   struct batadv_orig_node *orig_node,
509 			   struct batadv_tvlv_gateway_data *gateway)
510 {
511 	struct batadv_gw_node *gw_node, *curr_gw = NULL;
512 
513 	gw_node = batadv_gw_node_get(bat_priv, orig_node);
514 	if (!gw_node) {
515 		batadv_gw_node_add(bat_priv, orig_node, gateway);
516 		goto out;
517 	}
518 
519 	if ((gw_node->bandwidth_down == ntohl(gateway->bandwidth_down)) &&
520 	    (gw_node->bandwidth_up == ntohl(gateway->bandwidth_up)))
521 		goto out;
522 
523 	batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
524 		   "Gateway bandwidth of originator %pM changed from %u.%u/%u.%u MBit to %u.%u/%u.%u MBit\n",
525 		   orig_node->orig,
526 		   gw_node->bandwidth_down / 10,
527 		   gw_node->bandwidth_down % 10,
528 		   gw_node->bandwidth_up / 10,
529 		   gw_node->bandwidth_up % 10,
530 		   ntohl(gateway->bandwidth_down) / 10,
531 		   ntohl(gateway->bandwidth_down) % 10,
532 		   ntohl(gateway->bandwidth_up) / 10,
533 		   ntohl(gateway->bandwidth_up) % 10);
534 
535 	gw_node->bandwidth_down = ntohl(gateway->bandwidth_down);
536 	gw_node->bandwidth_up = ntohl(gateway->bandwidth_up);
537 
538 	if (ntohl(gateway->bandwidth_down) == 0) {
539 		batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
540 			   "Gateway %pM removed from gateway list\n",
541 			   orig_node->orig);
542 
543 		/* Note: We don't need a NULL check here, since curr_gw never
544 		 * gets dereferenced.
545 		 */
546 		spin_lock_bh(&bat_priv->gw.list_lock);
547 		if (!hlist_unhashed(&gw_node->list)) {
548 			hlist_del_init_rcu(&gw_node->list);
549 			batadv_gw_node_put(gw_node);
550 		}
551 		spin_unlock_bh(&bat_priv->gw.list_lock);
552 
553 		curr_gw = batadv_gw_get_selected_gw_node(bat_priv);
554 		if (gw_node == curr_gw)
555 			batadv_gw_reselect(bat_priv);
556 
557 		if (curr_gw)
558 			batadv_gw_node_put(curr_gw);
559 	}
560 
561 out:
562 	if (gw_node)
563 		batadv_gw_node_put(gw_node);
564 }
565 
566 void batadv_gw_node_delete(struct batadv_priv *bat_priv,
567 			   struct batadv_orig_node *orig_node)
568 {
569 	struct batadv_tvlv_gateway_data gateway;
570 
571 	gateway.bandwidth_down = 0;
572 	gateway.bandwidth_up = 0;
573 
574 	batadv_gw_node_update(bat_priv, orig_node, &gateway);
575 }
576 
577 void batadv_gw_node_free(struct batadv_priv *bat_priv)
578 {
579 	struct batadv_gw_node *gw_node;
580 	struct hlist_node *node_tmp;
581 
582 	spin_lock_bh(&bat_priv->gw.list_lock);
583 	hlist_for_each_entry_safe(gw_node, node_tmp,
584 				  &bat_priv->gw.list, list) {
585 		hlist_del_init_rcu(&gw_node->list);
586 		batadv_gw_node_put(gw_node);
587 	}
588 	spin_unlock_bh(&bat_priv->gw.list_lock);
589 }
590 
591 /* fails if orig_node has no router */
592 static int batadv_write_buffer_text(struct batadv_priv *bat_priv,
593 				    struct seq_file *seq,
594 				    const struct batadv_gw_node *gw_node)
595 {
596 	struct batadv_gw_node *curr_gw;
597 	struct batadv_neigh_node *router;
598 	struct batadv_neigh_ifinfo *router_ifinfo = NULL;
599 	int ret = -1;
600 
601 	router = batadv_orig_router_get(gw_node->orig_node, BATADV_IF_DEFAULT);
602 	if (!router)
603 		goto out;
604 
605 	router_ifinfo = batadv_neigh_ifinfo_get(router, BATADV_IF_DEFAULT);
606 	if (!router_ifinfo)
607 		goto out;
608 
609 	curr_gw = batadv_gw_get_selected_gw_node(bat_priv);
610 
611 	seq_printf(seq, "%s %pM (%3i) %pM [%10s]: %u.%u/%u.%u MBit\n",
612 		   (curr_gw == gw_node ? "=>" : "  "),
613 		   gw_node->orig_node->orig,
614 		   router_ifinfo->bat_iv.tq_avg, router->addr,
615 		   router->if_incoming->net_dev->name,
616 		   gw_node->bandwidth_down / 10,
617 		   gw_node->bandwidth_down % 10,
618 		   gw_node->bandwidth_up / 10,
619 		   gw_node->bandwidth_up % 10);
620 	ret = seq_has_overflowed(seq) ? -1 : 0;
621 
622 	if (curr_gw)
623 		batadv_gw_node_put(curr_gw);
624 out:
625 	if (router_ifinfo)
626 		batadv_neigh_ifinfo_put(router_ifinfo);
627 	if (router)
628 		batadv_neigh_node_put(router);
629 	return ret;
630 }
631 
632 int batadv_gw_client_seq_print_text(struct seq_file *seq, void *offset)
633 {
634 	struct net_device *net_dev = (struct net_device *)seq->private;
635 	struct batadv_priv *bat_priv = netdev_priv(net_dev);
636 	struct batadv_hard_iface *primary_if;
637 	struct batadv_gw_node *gw_node;
638 	int gw_count = 0;
639 
640 	primary_if = batadv_seq_print_text_primary_if_get(seq);
641 	if (!primary_if)
642 		goto out;
643 
644 	seq_printf(seq,
645 		   "      %-12s (%s/%i) %17s [%10s]: advertised uplink bandwidth ... [B.A.T.M.A.N. adv %s, MainIF/MAC: %s/%pM (%s)]\n",
646 		   "Gateway", "#", BATADV_TQ_MAX_VALUE, "Nexthop", "outgoingIF",
647 		   BATADV_SOURCE_VERSION, primary_if->net_dev->name,
648 		   primary_if->net_dev->dev_addr, net_dev->name);
649 
650 	rcu_read_lock();
651 	hlist_for_each_entry_rcu(gw_node, &bat_priv->gw.list, list) {
652 		/* fails if orig_node has no router */
653 		if (batadv_write_buffer_text(bat_priv, seq, gw_node) < 0)
654 			continue;
655 
656 		gw_count++;
657 	}
658 	rcu_read_unlock();
659 
660 	if (gw_count == 0)
661 		seq_puts(seq, "No gateways in range ...\n");
662 
663 out:
664 	if (primary_if)
665 		batadv_hardif_put(primary_if);
666 	return 0;
667 }
668 
669 /**
670  * batadv_gw_dhcp_recipient_get - check if a packet is a DHCP message
671  * @skb: the packet to check
672  * @header_len: a pointer to the batman-adv header size
673  * @chaddr: buffer where the client address will be stored. Valid
674  *  only if the function returns BATADV_DHCP_TO_CLIENT
675  *
676  * This function may re-allocate the data buffer of the skb passed as argument.
677  *
678  * Return:
679  * - BATADV_DHCP_NO if the packet is not a dhcp message or if there was an error
680  *   while parsing it
681  * - BATADV_DHCP_TO_SERVER if this is a message going to the DHCP server
682  * - BATADV_DHCP_TO_CLIENT if this is a message going to a DHCP client
683  */
684 enum batadv_dhcp_recipient
685 batadv_gw_dhcp_recipient_get(struct sk_buff *skb, unsigned int *header_len,
686 			     u8 *chaddr)
687 {
688 	enum batadv_dhcp_recipient ret = BATADV_DHCP_NO;
689 	struct ethhdr *ethhdr;
690 	struct iphdr *iphdr;
691 	struct ipv6hdr *ipv6hdr;
692 	struct udphdr *udphdr;
693 	struct vlan_ethhdr *vhdr;
694 	int chaddr_offset;
695 	__be16 proto;
696 	u8 *p;
697 
698 	/* check for ethernet header */
699 	if (!pskb_may_pull(skb, *header_len + ETH_HLEN))
700 		return BATADV_DHCP_NO;
701 
702 	ethhdr = eth_hdr(skb);
703 	proto = ethhdr->h_proto;
704 	*header_len += ETH_HLEN;
705 
706 	/* check for initial vlan header */
707 	if (proto == htons(ETH_P_8021Q)) {
708 		if (!pskb_may_pull(skb, *header_len + VLAN_HLEN))
709 			return BATADV_DHCP_NO;
710 
711 		vhdr = vlan_eth_hdr(skb);
712 		proto = vhdr->h_vlan_encapsulated_proto;
713 		*header_len += VLAN_HLEN;
714 	}
715 
716 	/* check for ip header */
717 	switch (proto) {
718 	case htons(ETH_P_IP):
719 		if (!pskb_may_pull(skb, *header_len + sizeof(*iphdr)))
720 			return BATADV_DHCP_NO;
721 
722 		iphdr = (struct iphdr *)(skb->data + *header_len);
723 		*header_len += iphdr->ihl * 4;
724 
725 		/* check for udp header */
726 		if (iphdr->protocol != IPPROTO_UDP)
727 			return BATADV_DHCP_NO;
728 
729 		break;
730 	case htons(ETH_P_IPV6):
731 		if (!pskb_may_pull(skb, *header_len + sizeof(*ipv6hdr)))
732 			return BATADV_DHCP_NO;
733 
734 		ipv6hdr = (struct ipv6hdr *)(skb->data + *header_len);
735 		*header_len += sizeof(*ipv6hdr);
736 
737 		/* check for udp header */
738 		if (ipv6hdr->nexthdr != IPPROTO_UDP)
739 			return BATADV_DHCP_NO;
740 
741 		break;
742 	default:
743 		return BATADV_DHCP_NO;
744 	}
745 
746 	if (!pskb_may_pull(skb, *header_len + sizeof(*udphdr)))
747 		return BATADV_DHCP_NO;
748 
749 	udphdr = (struct udphdr *)(skb->data + *header_len);
750 	*header_len += sizeof(*udphdr);
751 
752 	/* check for bootp port */
753 	switch (proto) {
754 	case htons(ETH_P_IP):
755 		if (udphdr->dest == htons(67))
756 			ret = BATADV_DHCP_TO_SERVER;
757 		else if (udphdr->source == htons(67))
758 			ret = BATADV_DHCP_TO_CLIENT;
759 		break;
760 	case htons(ETH_P_IPV6):
761 		if (udphdr->dest == htons(547))
762 			ret = BATADV_DHCP_TO_SERVER;
763 		else if (udphdr->source == htons(547))
764 			ret = BATADV_DHCP_TO_CLIENT;
765 		break;
766 	}
767 
768 	chaddr_offset = *header_len + BATADV_DHCP_CHADDR_OFFSET;
769 	/* store the client address if the message is going to a client */
770 	if (ret == BATADV_DHCP_TO_CLIENT &&
771 	    pskb_may_pull(skb, chaddr_offset + ETH_ALEN)) {
772 		/* check if the DHCP packet carries an Ethernet DHCP */
773 		p = skb->data + *header_len + BATADV_DHCP_HTYPE_OFFSET;
774 		if (*p != BATADV_DHCP_HTYPE_ETHERNET)
775 			return BATADV_DHCP_NO;
776 
777 		/* check if the DHCP packet carries a valid Ethernet address */
778 		p = skb->data + *header_len + BATADV_DHCP_HLEN_OFFSET;
779 		if (*p != ETH_ALEN)
780 			return BATADV_DHCP_NO;
781 
782 		ether_addr_copy(chaddr, skb->data + chaddr_offset);
783 	}
784 
785 	return ret;
786 }
787 
788 /**
789  * batadv_gw_out_of_range - check if the dhcp request destination is the best gw
790  * @bat_priv: the bat priv with all the soft interface information
791  * @skb: the outgoing packet
792  *
793  * Check if the skb is a DHCP request and if it is sent to the current best GW
794  * server. Due to topology changes it may be the case that the GW server
795  * previously selected is not the best one anymore.
796  *
797  * This call might reallocate skb data.
798  * Must be invoked only when the DHCP packet is going TO a DHCP SERVER.
799  *
800  * Return: true if the packet destination is unicast and it is not the best gw,
801  * false otherwise.
802  */
803 bool batadv_gw_out_of_range(struct batadv_priv *bat_priv,
804 			    struct sk_buff *skb)
805 {
806 	struct batadv_neigh_node *neigh_curr = NULL;
807 	struct batadv_neigh_node *neigh_old = NULL;
808 	struct batadv_orig_node *orig_dst_node = NULL;
809 	struct batadv_gw_node *gw_node = NULL;
810 	struct batadv_gw_node *curr_gw = NULL;
811 	struct batadv_neigh_ifinfo *curr_ifinfo, *old_ifinfo;
812 	struct ethhdr *ethhdr = (struct ethhdr *)skb->data;
813 	bool out_of_range = false;
814 	u8 curr_tq_avg;
815 	unsigned short vid;
816 
817 	vid = batadv_get_vid(skb, 0);
818 
819 	orig_dst_node = batadv_transtable_search(bat_priv, ethhdr->h_source,
820 						 ethhdr->h_dest, vid);
821 	if (!orig_dst_node)
822 		goto out;
823 
824 	gw_node = batadv_gw_node_get(bat_priv, orig_dst_node);
825 	if (!gw_node)
826 		goto out;
827 
828 	switch (atomic_read(&bat_priv->gw_mode)) {
829 	case BATADV_GW_MODE_SERVER:
830 		/* If we are a GW then we are our best GW. We can artificially
831 		 * set the tq towards ourself as the maximum value
832 		 */
833 		curr_tq_avg = BATADV_TQ_MAX_VALUE;
834 		break;
835 	case BATADV_GW_MODE_CLIENT:
836 		curr_gw = batadv_gw_get_selected_gw_node(bat_priv);
837 		if (!curr_gw)
838 			goto out;
839 
840 		/* packet is going to our gateway */
841 		if (curr_gw->orig_node == orig_dst_node)
842 			goto out;
843 
844 		/* If the dhcp packet has been sent to a different gw,
845 		 * we have to evaluate whether the old gw is still
846 		 * reliable enough
847 		 */
848 		neigh_curr = batadv_find_router(bat_priv, curr_gw->orig_node,
849 						NULL);
850 		if (!neigh_curr)
851 			goto out;
852 
853 		curr_ifinfo = batadv_neigh_ifinfo_get(neigh_curr,
854 						      BATADV_IF_DEFAULT);
855 		if (!curr_ifinfo)
856 			goto out;
857 
858 		curr_tq_avg = curr_ifinfo->bat_iv.tq_avg;
859 		batadv_neigh_ifinfo_put(curr_ifinfo);
860 
861 		break;
862 	case BATADV_GW_MODE_OFF:
863 	default:
864 		goto out;
865 	}
866 
867 	neigh_old = batadv_find_router(bat_priv, orig_dst_node, NULL);
868 	if (!neigh_old)
869 		goto out;
870 
871 	old_ifinfo = batadv_neigh_ifinfo_get(neigh_old, BATADV_IF_DEFAULT);
872 	if (!old_ifinfo)
873 		goto out;
874 
875 	if ((curr_tq_avg - old_ifinfo->bat_iv.tq_avg) > BATADV_GW_THRESHOLD)
876 		out_of_range = true;
877 	batadv_neigh_ifinfo_put(old_ifinfo);
878 
879 out:
880 	if (orig_dst_node)
881 		batadv_orig_node_put(orig_dst_node);
882 	if (curr_gw)
883 		batadv_gw_node_put(curr_gw);
884 	if (gw_node)
885 		batadv_gw_node_put(gw_node);
886 	if (neigh_old)
887 		batadv_neigh_node_put(neigh_old);
888 	if (neigh_curr)
889 		batadv_neigh_node_put(neigh_curr);
890 	return out_of_range;
891 }
892