gateway_client.c

  1// SPDX-License-Identifier: GPL-2.0
  2/* Copyright (C) B.A.T.M.A.N. contributors:
  3 *
  4 * Marek Lindner
  5 */
  6
  7#include "gateway_client.h"
  8#include "main.h"
  9
 10#include <linux/atomic.h>
 11#include <linux/byteorder/generic.h>
 12#include <linux/container_of.h>
 13#include <linux/err.h>
 14#include <linux/errno.h>
 15#include <linux/etherdevice.h>
 16#include <linux/gfp.h>
 17#include <linux/if_ether.h>
 18#include <linux/if_vlan.h>
 19#include <linux/in.h>
 20#include <linux/ip.h>
 21#include <linux/ipv6.h>
 22#include <linux/kref.h>
 23#include <linux/list.h>
 24#include <linux/lockdep.h>
 25#include <linux/netdevice.h>
 26#include <linux/netlink.h>
 27#include <linux/rculist.h>
 28#include <linux/rcupdate.h>
 29#include <linux/skbuff.h>
 30#include <linux/slab.h>
 31#include <linux/spinlock.h>
 32#include <linux/sprintf.h>
 33#include <linux/stddef.h>
 34#include <linux/udp.h>
 35#include <uapi/linux/batadv_packet.h>
 36#include <uapi/linux/batman_adv.h>
 37
 38#include "hard-interface.h"
 39#include "log.h"
 40#include "netlink.h"
 41#include "originator.h"
 42#include "routing.h"
 43#include "translation-table.h"
 44
 45/* These are the offsets of the "hw type" and "hw address length" in the dhcp
 46 * packet starting at the beginning of the dhcp header
 47 */
 48#define BATADV_DHCP_HTYPE_OFFSET	1
 49#define BATADV_DHCP_HLEN_OFFSET		2
 50/* Value of htype representing Ethernet */
 51#define BATADV_DHCP_HTYPE_ETHERNET	0x01
 52/* This is the offset of the "chaddr" field in the dhcp packet starting at the
 53 * beginning of the dhcp header
 54 */
 55#define BATADV_DHCP_CHADDR_OFFSET	28
 56
 57/**
 58 * batadv_gw_node_release() - release gw_node from lists and queue for free
 59 *  after rcu grace period
 60 * @ref: kref pointer of the gw_node
 61 */
 62void batadv_gw_node_release(struct kref *ref)
 63{
 64	struct batadv_gw_node *gw_node;
 65
 66	gw_node = container_of(ref, struct batadv_gw_node, refcount);
 67
 68	batadv_orig_node_put(gw_node->orig_node);
 69	kfree_rcu(gw_node, rcu);
 70}
 71
 72/**
 73 * batadv_gw_get_selected_gw_node() - Get currently selected gateway
 74 * @bat_priv: the bat priv with all the mesh interface information
 75 *
 76 * Return: selected gateway (with increased refcnt), NULL on errors
 77 */
 78struct batadv_gw_node *
 79batadv_gw_get_selected_gw_node(struct batadv_priv *bat_priv)
 80{
 81	struct batadv_gw_node *gw_node;
 82
 83	rcu_read_lock();
 84	gw_node = rcu_dereference(bat_priv->gw.curr_gw);
 85	if (!gw_node)
 86		goto out;
 87
 88	if (!kref_get_unless_zero(&gw_node->refcount))
 89		gw_node = NULL;
 90
 91out:
 92	rcu_read_unlock();
 93	return gw_node;
 94}
 95
 96/**
 97 * batadv_gw_get_selected_orig() - Get originator of currently selected gateway
 98 * @bat_priv: the bat priv with all the mesh interface information
 99 *
100 * Return: orig_node of selected gateway (with increased refcnt), NULL on errors
101 */
102struct batadv_orig_node *
103batadv_gw_get_selected_orig(struct batadv_priv *bat_priv)
104{
105	struct batadv_gw_node *gw_node;
106	struct batadv_orig_node *orig_node = NULL;
107
108	gw_node = batadv_gw_get_selected_gw_node(bat_priv);
109	if (!gw_node)
110		goto out;
111
112	rcu_read_lock();
113	orig_node = gw_node->orig_node;
114	if (!orig_node)
115		goto unlock;
116
117	if (!kref_get_unless_zero(&orig_node->refcount))
118		orig_node = NULL;
119
120unlock:
121	rcu_read_unlock();
122out:
123	batadv_gw_node_put(gw_node);
124	return orig_node;
125}
126
127static void batadv_gw_select(struct batadv_priv *bat_priv,
128			     struct batadv_gw_node *new_gw_node)
129{
130	struct batadv_gw_node *curr_gw_node;
131
132	spin_lock_bh(&bat_priv->gw.list_lock);
133
134	if (new_gw_node)
135		kref_get(&new_gw_node->refcount);
136
137	curr_gw_node = rcu_replace_pointer(bat_priv->gw.curr_gw, new_gw_node,
138					   true);
139
140	batadv_gw_node_put(curr_gw_node);
141
142	spin_unlock_bh(&bat_priv->gw.list_lock);
143}
144
145/**
146 * batadv_gw_reselect() - force a gateway reselection
147 * @bat_priv: the bat priv with all the mesh interface information
148 *
149 * Set a flag to remind the GW component to perform a new gateway reselection.
150 * However this function does not ensure that the current gateway is going to be
151 * deselected. The reselection mechanism may elect the same gateway once again.
152 *
153 * This means that invoking batadv_gw_reselect() does not guarantee a gateway
154 * change and therefore a uevent is not necessarily expected.
155 */
156void batadv_gw_reselect(struct batadv_priv *bat_priv)
157{
158	atomic_set(&bat_priv->gw.reselect, 1);
159}
160
161/**
162 * batadv_gw_check_client_stop() - check if client mode has been switched off
163 * @bat_priv: the bat priv with all the mesh interface information
164 *
165 * This function assumes the caller has checked that the gw state *is actually
166 * changing*. This function is not supposed to be called when there is no state
167 * change.
168 */
169void batadv_gw_check_client_stop(struct batadv_priv *bat_priv)
170{
171	struct batadv_gw_node *curr_gw;
172
173	if (atomic_read(&bat_priv->gw.mode) != BATADV_GW_MODE_CLIENT)
174		return;
175
176	curr_gw = batadv_gw_get_selected_gw_node(bat_priv);
177	if (!curr_gw)
178		return;
179
180	/* deselect the current gateway so that next time that client mode is
181	 * enabled a proper GW_ADD event can be sent
182	 */
183	batadv_gw_select(bat_priv, NULL);
184
185	/* if batman-adv is switching the gw client mode off and a gateway was
186	 * already selected, send a DEL uevent
187	 */
188	batadv_throw_uevent(bat_priv, BATADV_UEV_GW, BATADV_UEV_DEL, NULL);
189
190	batadv_gw_node_put(curr_gw);
191}
192
193/**
194 * batadv_gw_election() - Elect the best gateway
195 * @bat_priv: the bat priv with all the mesh interface information
196 */
197void batadv_gw_election(struct batadv_priv *bat_priv)
198{
199	struct batadv_gw_node *curr_gw = NULL;
200	struct batadv_gw_node *next_gw = NULL;
201	struct batadv_neigh_node *router = NULL;
202	struct batadv_neigh_ifinfo *router_ifinfo = NULL;
203	char gw_addr[18] = { '\0' };
204
205	if (atomic_read(&bat_priv->gw.mode) != BATADV_GW_MODE_CLIENT)
206		goto out;
207
208	if (!bat_priv->algo_ops->gw.get_best_gw_node)
209		goto out;
210
211	curr_gw = batadv_gw_get_selected_gw_node(bat_priv);
212
213	if (!batadv_atomic_dec_not_zero(&bat_priv->gw.reselect) && curr_gw)
214		goto out;
215
216	/* if gw.reselect is set to 1 it means that a previous call to
217	 * gw.is_eligible() said that we have a new best GW, therefore it can
218	 * now be picked from the list and selected
219	 */
220	next_gw = bat_priv->algo_ops->gw.get_best_gw_node(bat_priv);
221
222	if (curr_gw == next_gw)
223		goto out;
224
225	if (next_gw) {
226		sprintf(gw_addr, "%pM", next_gw->orig_node->orig);
227
228		router = batadv_orig_router_get(next_gw->orig_node,
229						BATADV_IF_DEFAULT);
230		if (!router) {
231			batadv_gw_reselect(bat_priv);
232			goto out;
233		}
234
235		router_ifinfo = batadv_neigh_ifinfo_get(router,
236							BATADV_IF_DEFAULT);
237		if (!router_ifinfo) {
238			batadv_gw_reselect(bat_priv);
239			goto out;
240		}
241	}
242
243	if (curr_gw && !next_gw) {
244		batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
245			   "Removing selected gateway - no gateway in range\n");
246		batadv_throw_uevent(bat_priv, BATADV_UEV_GW, BATADV_UEV_DEL,
247				    NULL);
248	} else if (!curr_gw && next_gw) {
249		batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
250			   "Adding route to gateway %pM (bandwidth: %u.%u/%u.%u MBit, tq: %i)\n",
251			   next_gw->orig_node->orig,
252			   next_gw->bandwidth_down / 10,
253			   next_gw->bandwidth_down % 10,
254			   next_gw->bandwidth_up / 10,
255			   next_gw->bandwidth_up % 10,
256			   router_ifinfo->bat_iv.tq_avg);
257		batadv_throw_uevent(bat_priv, BATADV_UEV_GW, BATADV_UEV_ADD,
258				    gw_addr);
259	} else {
260		batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
261			   "Changing route to gateway %pM (bandwidth: %u.%u/%u.%u MBit, tq: %i)\n",
262			   next_gw->orig_node->orig,
263			   next_gw->bandwidth_down / 10,
264			   next_gw->bandwidth_down % 10,
265			   next_gw->bandwidth_up / 10,
266			   next_gw->bandwidth_up % 10,
267			   router_ifinfo->bat_iv.tq_avg);
268		batadv_throw_uevent(bat_priv, BATADV_UEV_GW, BATADV_UEV_CHANGE,
269				    gw_addr);
270	}
271
272	batadv_gw_select(bat_priv, next_gw);
273
274out:
275	batadv_gw_node_put(curr_gw);
276	batadv_gw_node_put(next_gw);
277	batadv_neigh_node_put(router);
278	batadv_neigh_ifinfo_put(router_ifinfo);
279}
280
281/**
282 * batadv_gw_check_election() - Elect orig node as best gateway when eligible
283 * @bat_priv: the bat priv with all the mesh interface information
284 * @orig_node: orig node which is to be checked
285 */
286void batadv_gw_check_election(struct batadv_priv *bat_priv,
287			      struct batadv_orig_node *orig_node)
288{
289	struct batadv_orig_node *curr_gw_orig;
290
291	/* abort immediately if the routing algorithm does not support gateway
292	 * election
293	 */
294	if (!bat_priv->algo_ops->gw.is_eligible)
295		return;
296
297	curr_gw_orig = batadv_gw_get_selected_orig(bat_priv);
298	if (!curr_gw_orig)
299		goto reselect;
300
301	/* this node already is the gateway */
302	if (curr_gw_orig == orig_node)
303		goto out;
304
305	if (!bat_priv->algo_ops->gw.is_eligible(bat_priv, curr_gw_orig,
306						orig_node))
307		goto out;
308
309reselect:
310	batadv_gw_reselect(bat_priv);
311out:
312	batadv_orig_node_put(curr_gw_orig);
313}
314
315/**
316 * batadv_gw_node_add() - add gateway node to list of available gateways
317 * @bat_priv: the bat priv with all the mesh interface information
318 * @orig_node: originator announcing gateway capabilities
319 * @gateway: announced bandwidth information
320 *
321 * Has to be called with the appropriate locks being acquired
322 * (gw.list_lock).
323 */
324static void batadv_gw_node_add(struct batadv_priv *bat_priv,
325			       struct batadv_orig_node *orig_node,
326			       struct batadv_tvlv_gateway_data *gateway)
327{
328	struct batadv_gw_node *gw_node;
329
330	lockdep_assert_held(&bat_priv->gw.list_lock);
331
332	if (gateway->bandwidth_down == 0)
333		return;
334
335	gw_node = kzalloc(sizeof(*gw_node), GFP_ATOMIC);
336	if (!gw_node)
337		return;
338
339	kref_init(&gw_node->refcount);
340	INIT_HLIST_NODE(&gw_node->list);
341	kref_get(&orig_node->refcount);
342	gw_node->orig_node = orig_node;
343	gw_node->bandwidth_down = ntohl(gateway->bandwidth_down);
344	gw_node->bandwidth_up = ntohl(gateway->bandwidth_up);
345
346	kref_get(&gw_node->refcount);
347	hlist_add_head_rcu(&gw_node->list, &bat_priv->gw.gateway_list);
348	bat_priv->gw.generation++;
349
350	batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
351		   "Found new gateway %pM -> gw bandwidth: %u.%u/%u.%u MBit\n",
352		   orig_node->orig,
353		   ntohl(gateway->bandwidth_down) / 10,
354		   ntohl(gateway->bandwidth_down) % 10,
355		   ntohl(gateway->bandwidth_up) / 10,
356		   ntohl(gateway->bandwidth_up) % 10);
357
358	/* don't return reference to new gw_node */
359	batadv_gw_node_put(gw_node);
360}
361
362/**
363 * batadv_gw_node_get() - retrieve gateway node from list of available gateways
364 * @bat_priv: the bat priv with all the mesh interface information
365 * @orig_node: originator announcing gateway capabilities
366 *
367 * Return: gateway node if found or NULL otherwise.
368 */
369struct batadv_gw_node *batadv_gw_node_get(struct batadv_priv *bat_priv,
370					  struct batadv_orig_node *orig_node)
371{
372	struct batadv_gw_node *gw_node_tmp, *gw_node = NULL;
373
374	rcu_read_lock();
375	hlist_for_each_entry_rcu(gw_node_tmp, &bat_priv->gw.gateway_list,
376				 list) {
377		if (gw_node_tmp->orig_node != orig_node)
378			continue;
379
380		if (!kref_get_unless_zero(&gw_node_tmp->refcount))
381			continue;
382
383		gw_node = gw_node_tmp;
384		break;
385	}
386	rcu_read_unlock();
387
388	return gw_node;
389}
390
391/**
392 * batadv_gw_node_update() - update list of available gateways with changed
393 *  bandwidth information
394 * @bat_priv: the bat priv with all the mesh interface information
395 * @orig_node: originator announcing gateway capabilities
396 * @gateway: announced bandwidth information
397 */
398void batadv_gw_node_update(struct batadv_priv *bat_priv,
399			   struct batadv_orig_node *orig_node,
400			   struct batadv_tvlv_gateway_data *gateway)
401{
402	struct batadv_gw_node *gw_node, *curr_gw = NULL;
403
404	spin_lock_bh(&bat_priv->gw.list_lock);
405	gw_node = batadv_gw_node_get(bat_priv, orig_node);
406	if (!gw_node) {
407		batadv_gw_node_add(bat_priv, orig_node, gateway);
408		spin_unlock_bh(&bat_priv->gw.list_lock);
409		goto out;
410	}
411	spin_unlock_bh(&bat_priv->gw.list_lock);
412
413	if (gw_node->bandwidth_down == ntohl(gateway->bandwidth_down) &&
414	    gw_node->bandwidth_up == ntohl(gateway->bandwidth_up))
415		goto out;
416
417	batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
418		   "Gateway bandwidth of originator %pM changed from %u.%u/%u.%u MBit to %u.%u/%u.%u MBit\n",
419		   orig_node->orig,
420		   gw_node->bandwidth_down / 10,
421		   gw_node->bandwidth_down % 10,
422		   gw_node->bandwidth_up / 10,
423		   gw_node->bandwidth_up % 10,
424		   ntohl(gateway->bandwidth_down) / 10,
425		   ntohl(gateway->bandwidth_down) % 10,
426		   ntohl(gateway->bandwidth_up) / 10,
427		   ntohl(gateway->bandwidth_up) % 10);
428
429	gw_node->bandwidth_down = ntohl(gateway->bandwidth_down);
430	gw_node->bandwidth_up = ntohl(gateway->bandwidth_up);
431
432	if (ntohl(gateway->bandwidth_down) == 0) {
433		batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
434			   "Gateway %pM removed from gateway list\n",
435			   orig_node->orig);
436
437		/* Note: We don't need a NULL check here, since curr_gw never
438		 * gets dereferenced.
439		 */
440		spin_lock_bh(&bat_priv->gw.list_lock);
441		if (!hlist_unhashed(&gw_node->list)) {
442			hlist_del_init_rcu(&gw_node->list);
443			batadv_gw_node_put(gw_node);
444			bat_priv->gw.generation++;
445		}
446		spin_unlock_bh(&bat_priv->gw.list_lock);
447
448		curr_gw = batadv_gw_get_selected_gw_node(bat_priv);
449		if (gw_node == curr_gw)
450			batadv_gw_reselect(bat_priv);
451
452		batadv_gw_node_put(curr_gw);
453	}
454
455out:
456	batadv_gw_node_put(gw_node);
457}
458
459/**
460 * batadv_gw_node_delete() - Remove orig_node from gateway list
461 * @bat_priv: the bat priv with all the mesh interface information
462 * @orig_node: orig node which is currently in process of being removed
463 */
464void batadv_gw_node_delete(struct batadv_priv *bat_priv,
465			   struct batadv_orig_node *orig_node)
466{
467	struct batadv_tvlv_gateway_data gateway;
468
469	gateway.bandwidth_down = 0;
470	gateway.bandwidth_up = 0;
471
472	batadv_gw_node_update(bat_priv, orig_node, &gateway);
473}
474
475/**
476 * batadv_gw_node_free() - Free gateway information from mesh interface
477 * @bat_priv: the bat priv with all the mesh interface information
478 */
479void batadv_gw_node_free(struct batadv_priv *bat_priv)
480{
481	struct batadv_gw_node *gw_node;
482	struct hlist_node *node_tmp;
483
484	spin_lock_bh(&bat_priv->gw.list_lock);
485	hlist_for_each_entry_safe(gw_node, node_tmp,
486				  &bat_priv->gw.gateway_list, list) {
487		hlist_del_init_rcu(&gw_node->list);
488		batadv_gw_node_put(gw_node);
489		bat_priv->gw.generation++;
490	}
491	spin_unlock_bh(&bat_priv->gw.list_lock);
492}
493
494/**
495 * batadv_gw_dump() - Dump gateways into a message
496 * @msg: Netlink message to dump into
497 * @cb: Control block containing additional options
498 *
499 * Return: Error code, or length of message
500 */
501int batadv_gw_dump(struct sk_buff *msg, struct netlink_callback *cb)
502{
503	struct batadv_hard_iface *primary_if = NULL;
504	struct net_device *mesh_iface;
505	struct batadv_priv *bat_priv;
506	int ret;
507
508	mesh_iface = batadv_netlink_get_meshif(cb);
509	if (IS_ERR(mesh_iface))
510		return PTR_ERR(mesh_iface);
511
512	bat_priv = netdev_priv(mesh_iface);
513
514	primary_if = batadv_primary_if_get_selected(bat_priv);
515	if (!primary_if || primary_if->if_status != BATADV_IF_ACTIVE) {
516		ret = -ENOENT;
517		goto out;
518	}
519
520	if (!bat_priv->algo_ops->gw.dump) {
521		ret = -EOPNOTSUPP;
522		goto out;
523	}
524
525	bat_priv->algo_ops->gw.dump(msg, cb, bat_priv);
526
527	ret = msg->len;
528
529out:
530	batadv_hardif_put(primary_if);
531	dev_put(mesh_iface);
532
533	return ret;
534}
535
536/**
537 * batadv_gw_dhcp_recipient_get() - check if a packet is a DHCP message
538 * @skb: the packet to check
539 * @header_len: a pointer to the batman-adv header size
540 * @chaddr: buffer where the client address will be stored. Valid
541 *  only if the function returns BATADV_DHCP_TO_CLIENT
542 *
543 * This function may re-allocate the data buffer of the skb passed as argument.
544 *
545 * Return:
546 * - BATADV_DHCP_NO if the packet is not a dhcp message or if there was an error
547 *   while parsing it
548 * - BATADV_DHCP_TO_SERVER if this is a message going to the DHCP server
549 * - BATADV_DHCP_TO_CLIENT if this is a message going to a DHCP client
550 */
551enum batadv_dhcp_recipient
552batadv_gw_dhcp_recipient_get(struct sk_buff *skb, unsigned int *header_len,
553			     u8 *chaddr)
554{
555	enum batadv_dhcp_recipient ret = BATADV_DHCP_NO;
556	struct ethhdr *ethhdr;
557	struct iphdr *iphdr;
558	struct ipv6hdr *ipv6hdr;
559	struct udphdr *udphdr;
560	struct vlan_ethhdr *vhdr;
561	int chaddr_offset;
562	__be16 proto;
563	u8 *p;
564
565	/* check for ethernet header */
566	if (!pskb_may_pull(skb, *header_len + ETH_HLEN))
567		return BATADV_DHCP_NO;
568
569	ethhdr = eth_hdr(skb);
570	proto = ethhdr->h_proto;
571	*header_len += ETH_HLEN;
572
573	/* check for initial vlan header */
574	if (proto == htons(ETH_P_8021Q)) {
575		if (!pskb_may_pull(skb, *header_len + VLAN_HLEN))
576			return BATADV_DHCP_NO;
577
578		vhdr = vlan_eth_hdr(skb);
579		proto = vhdr->h_vlan_encapsulated_proto;
580		*header_len += VLAN_HLEN;
581	}
582
583	/* check for ip header */
584	switch (proto) {
585	case htons(ETH_P_IP):
586		if (!pskb_may_pull(skb, *header_len + sizeof(*iphdr)))
587			return BATADV_DHCP_NO;
588
589		iphdr = (struct iphdr *)(skb->data + *header_len);
590		*header_len += iphdr->ihl * 4;
591
592		/* check for udp header */
593		if (iphdr->protocol != IPPROTO_UDP)
594			return BATADV_DHCP_NO;
595
596		break;
597	case htons(ETH_P_IPV6):
598		if (!pskb_may_pull(skb, *header_len + sizeof(*ipv6hdr)))
599			return BATADV_DHCP_NO;
600
601		ipv6hdr = (struct ipv6hdr *)(skb->data + *header_len);
602		*header_len += sizeof(*ipv6hdr);
603
604		/* check for udp header */
605		if (ipv6hdr->nexthdr != IPPROTO_UDP)
606			return BATADV_DHCP_NO;
607
608		break;
609	default:
610		return BATADV_DHCP_NO;
611	}
612
613	if (!pskb_may_pull(skb, *header_len + sizeof(*udphdr)))
614		return BATADV_DHCP_NO;
615
616	udphdr = (struct udphdr *)(skb->data + *header_len);
617	*header_len += sizeof(*udphdr);
618
619	/* check for bootp port */
620	switch (proto) {
621	case htons(ETH_P_IP):
622		if (udphdr->dest == htons(67))
623			ret = BATADV_DHCP_TO_SERVER;
624		else if (udphdr->source == htons(67))
625			ret = BATADV_DHCP_TO_CLIENT;
626		break;
627	case htons(ETH_P_IPV6):
628		if (udphdr->dest == htons(547))
629			ret = BATADV_DHCP_TO_SERVER;
630		else if (udphdr->source == htons(547))
631			ret = BATADV_DHCP_TO_CLIENT;
632		break;
633	}
634
635	chaddr_offset = *header_len + BATADV_DHCP_CHADDR_OFFSET;
636	/* store the client address if the message is going to a client */
637	if (ret == BATADV_DHCP_TO_CLIENT) {
638		if (!pskb_may_pull(skb, chaddr_offset + ETH_ALEN))
639			return BATADV_DHCP_NO;
640
641		/* check if the DHCP packet carries an Ethernet DHCP */
642		p = skb->data + *header_len + BATADV_DHCP_HTYPE_OFFSET;
643		if (*p != BATADV_DHCP_HTYPE_ETHERNET)
644			return BATADV_DHCP_NO;
645
646		/* check if the DHCP packet carries a valid Ethernet address */
647		p = skb->data + *header_len + BATADV_DHCP_HLEN_OFFSET;
648		if (*p != ETH_ALEN)
649			return BATADV_DHCP_NO;
650
651		ether_addr_copy(chaddr, skb->data + chaddr_offset);
652	}
653
654	return ret;
655}
656
657/**
658 * batadv_gw_out_of_range() - check if the dhcp request destination is the best
659 *  gateway
660 * @bat_priv: the bat priv with all the mesh interface information
661 * @skb: the outgoing packet
662 *
663 * Check if the skb is a DHCP request and if it is sent to the current best GW
664 * server. Due to topology changes it may be the case that the GW server
665 * previously selected is not the best one anymore.
666 *
667 * This call might reallocate skb data.
668 * Must be invoked only when the DHCP packet is going TO a DHCP SERVER.
669 *
670 * Return: true if the packet destination is unicast and it is not the best gw,
671 * false otherwise.
672 */
673bool batadv_gw_out_of_range(struct batadv_priv *bat_priv,
674			    struct sk_buff *skb)
675{
676	struct batadv_neigh_node *neigh_curr = NULL;
677	struct batadv_neigh_node *neigh_old = NULL;
678	struct batadv_orig_node *orig_dst_node = NULL;
679	struct batadv_gw_node *gw_node = NULL;
680	struct batadv_gw_node *curr_gw = NULL;
681	struct batadv_neigh_ifinfo *curr_ifinfo, *old_ifinfo;
682	struct ethhdr *ethhdr = (struct ethhdr *)skb->data;
683	bool out_of_range = false;
684	u8 curr_tq_avg;
685	unsigned short vid;
686
687	vid = batadv_get_vid(skb, 0);
688
689	if (is_multicast_ether_addr(ethhdr->h_dest))
690		goto out;
691
692	orig_dst_node = batadv_transtable_search(bat_priv, ethhdr->h_source,
693						 ethhdr->h_dest, vid);
694	if (!orig_dst_node)
695		goto out;
696
697	gw_node = batadv_gw_node_get(bat_priv, orig_dst_node);
698	if (!gw_node)
699		goto out;
700
701	switch (atomic_read(&bat_priv->gw.mode)) {
702	case BATADV_GW_MODE_SERVER:
703		/* If we are a GW then we are our best GW. We can artificially
704		 * set the tq towards ourself as the maximum value
705		 */
706		curr_tq_avg = BATADV_TQ_MAX_VALUE;
707		break;
708	case BATADV_GW_MODE_CLIENT:
709		curr_gw = batadv_gw_get_selected_gw_node(bat_priv);
710		if (!curr_gw)
711			goto out;
712
713		/* packet is going to our gateway */
714		if (curr_gw->orig_node == orig_dst_node)
715			goto out;
716
717		/* If the dhcp packet has been sent to a different gw,
718		 * we have to evaluate whether the old gw is still
719		 * reliable enough
720		 */
721		neigh_curr = batadv_find_router(bat_priv, curr_gw->orig_node,
722						NULL);
723		if (!neigh_curr)
724			goto out;
725
726		curr_ifinfo = batadv_neigh_ifinfo_get(neigh_curr,
727						      BATADV_IF_DEFAULT);
728		if (!curr_ifinfo)
729			goto out;
730
731		curr_tq_avg = curr_ifinfo->bat_iv.tq_avg;
732		batadv_neigh_ifinfo_put(curr_ifinfo);
733
734		break;
735	case BATADV_GW_MODE_OFF:
736	default:
737		goto out;
738	}
739
740	neigh_old = batadv_find_router(bat_priv, orig_dst_node, NULL);
741	if (!neigh_old)
742		goto out;
743
744	old_ifinfo = batadv_neigh_ifinfo_get(neigh_old, BATADV_IF_DEFAULT);
745	if (!old_ifinfo)
746		goto out;
747
748	if ((curr_tq_avg - old_ifinfo->bat_iv.tq_avg) > BATADV_GW_THRESHOLD)
749		out_of_range = true;
750	batadv_neigh_ifinfo_put(old_ifinfo);
751
752out:
753	batadv_orig_node_put(orig_dst_node);
754	batadv_gw_node_put(curr_gw);
755	batadv_gw_node_put(gw_node);
756	batadv_neigh_node_put(neigh_old);
757	batadv_neigh_node_put(neigh_curr);
758	return out_of_range;
759}