batman-adv: filter ARP packets with invalid MAC addresses in DAT
[~shefty/rdma-dev.git] / net / batman-adv / gateway_client.c
1 /* Copyright (C) 2009-2012 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, write to the Free Software
16  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
17  * 02110-1301, USA
18  */
19
20 #include "main.h"
21 #include "sysfs.h"
22 #include "gateway_client.h"
23 #include "gateway_common.h"
24 #include "hard-interface.h"
25 #include "originator.h"
26 #include "translation-table.h"
27 #include "routing.h"
28 #include <linux/ip.h>
29 #include <linux/ipv6.h>
30 #include <linux/udp.h>
31 #include <linux/if_vlan.h>
32
33 /* This is the offset of the options field in a dhcp packet starting at
34  * the beginning of the dhcp header
35  */
36 #define BATADV_DHCP_OPTIONS_OFFSET 240
37 #define BATADV_DHCP_REQUEST 3
38
39 static void batadv_gw_node_free_ref(struct batadv_gw_node *gw_node)
40 {
41         if (atomic_dec_and_test(&gw_node->refcount))
42                 kfree_rcu(gw_node, rcu);
43 }
44
45 static struct batadv_gw_node *
46 batadv_gw_get_selected_gw_node(struct batadv_priv *bat_priv)
47 {
48         struct batadv_gw_node *gw_node;
49
50         rcu_read_lock();
51         gw_node = rcu_dereference(bat_priv->gw.curr_gw);
52         if (!gw_node)
53                 goto out;
54
55         if (!atomic_inc_not_zero(&gw_node->refcount))
56                 gw_node = NULL;
57
58 out:
59         rcu_read_unlock();
60         return gw_node;
61 }
62
63 struct batadv_orig_node *
64 batadv_gw_get_selected_orig(struct batadv_priv *bat_priv)
65 {
66         struct batadv_gw_node *gw_node;
67         struct batadv_orig_node *orig_node = NULL;
68
69         gw_node = batadv_gw_get_selected_gw_node(bat_priv);
70         if (!gw_node)
71                 goto out;
72
73         rcu_read_lock();
74         orig_node = gw_node->orig_node;
75         if (!orig_node)
76                 goto unlock;
77
78         if (!atomic_inc_not_zero(&orig_node->refcount))
79                 orig_node = NULL;
80
81 unlock:
82         rcu_read_unlock();
83 out:
84         if (gw_node)
85                 batadv_gw_node_free_ref(gw_node);
86         return orig_node;
87 }
88
89 static void batadv_gw_select(struct batadv_priv *bat_priv,
90                              struct batadv_gw_node *new_gw_node)
91 {
92         struct batadv_gw_node *curr_gw_node;
93
94         spin_lock_bh(&bat_priv->gw.list_lock);
95
96         if (new_gw_node && !atomic_inc_not_zero(&new_gw_node->refcount))
97                 new_gw_node = NULL;
98
99         curr_gw_node = rcu_dereference_protected(bat_priv->gw.curr_gw, 1);
100         rcu_assign_pointer(bat_priv->gw.curr_gw, new_gw_node);
101
102         if (curr_gw_node)
103                 batadv_gw_node_free_ref(curr_gw_node);
104
105         spin_unlock_bh(&bat_priv->gw.list_lock);
106 }
107
108 void batadv_gw_deselect(struct batadv_priv *bat_priv)
109 {
110         atomic_set(&bat_priv->gw.reselect, 1);
111 }
112
113 static struct batadv_gw_node *
114 batadv_gw_get_best_gw_node(struct batadv_priv *bat_priv)
115 {
116         struct batadv_neigh_node *router;
117         struct hlist_node *node;
118         struct batadv_gw_node *gw_node, *curr_gw = NULL;
119         uint32_t max_gw_factor = 0, tmp_gw_factor = 0;
120         uint32_t gw_divisor;
121         uint8_t max_tq = 0;
122         int down, up;
123         uint8_t tq_avg;
124         struct batadv_orig_node *orig_node;
125
126         gw_divisor = BATADV_TQ_LOCAL_WINDOW_SIZE * BATADV_TQ_LOCAL_WINDOW_SIZE;
127         gw_divisor *= 64;
128
129         rcu_read_lock();
130         hlist_for_each_entry_rcu(gw_node, node, &bat_priv->gw.list, list) {
131                 if (gw_node->deleted)
132                         continue;
133
134                 orig_node = gw_node->orig_node;
135                 router = batadv_orig_node_get_router(orig_node);
136                 if (!router)
137                         continue;
138
139                 if (!atomic_inc_not_zero(&gw_node->refcount))
140                         goto next;
141
142                 tq_avg = router->tq_avg;
143
144                 switch (atomic_read(&bat_priv->gw_sel_class)) {
145                 case 1: /* fast connection */
146                         batadv_gw_bandwidth_to_kbit(orig_node->gw_flags,
147                                                     &down, &up);
148
149                         tmp_gw_factor = tq_avg * tq_avg * down * 100 * 100;
150                         tmp_gw_factor /= gw_divisor;
151
152                         if ((tmp_gw_factor > max_gw_factor) ||
153                             ((tmp_gw_factor == max_gw_factor) &&
154                              (tq_avg > max_tq))) {
155                                 if (curr_gw)
156                                         batadv_gw_node_free_ref(curr_gw);
157                                 curr_gw = gw_node;
158                                 atomic_inc(&curr_gw->refcount);
159                         }
160                         break;
161
162                 default: /* 2:  stable connection (use best statistic)
163                           * 3:  fast-switch (use best statistic but change as
164                           *     soon as a better gateway appears)
165                           * XX: late-switch (use best statistic but change as
166                           *     soon as a better gateway appears which has
167                           *     $routing_class more tq points)
168                           */
169                         if (tq_avg > max_tq) {
170                                 if (curr_gw)
171                                         batadv_gw_node_free_ref(curr_gw);
172                                 curr_gw = gw_node;
173                                 atomic_inc(&curr_gw->refcount);
174                         }
175                         break;
176                 }
177
178                 if (tq_avg > max_tq)
179                         max_tq = tq_avg;
180
181                 if (tmp_gw_factor > max_gw_factor)
182                         max_gw_factor = tmp_gw_factor;
183
184                 batadv_gw_node_free_ref(gw_node);
185
186 next:
187                 batadv_neigh_node_free_ref(router);
188         }
189         rcu_read_unlock();
190
191         return curr_gw;
192 }
193
194 void batadv_gw_election(struct batadv_priv *bat_priv)
195 {
196         struct batadv_gw_node *curr_gw = NULL, *next_gw = NULL;
197         struct batadv_neigh_node *router = NULL;
198         char gw_addr[18] = { '\0' };
199
200         /* The batman daemon checks here if we already passed a full originator
201          * cycle in order to make sure we don't choose the first gateway we
202          * hear about. This check is based on the daemon's uptime which we
203          * don't have.
204          */
205         if (atomic_read(&bat_priv->gw_mode) != BATADV_GW_MODE_CLIENT)
206                 goto out;
207
208         curr_gw = batadv_gw_get_selected_gw_node(bat_priv);
209
210         if (!batadv_atomic_dec_not_zero(&bat_priv->gw.reselect) && curr_gw)
211                 goto out;
212
213         next_gw = batadv_gw_get_best_gw_node(bat_priv);
214
215         if (curr_gw == next_gw)
216                 goto out;
217
218         if (next_gw) {
219                 sprintf(gw_addr, "%pM", next_gw->orig_node->orig);
220
221                 router = batadv_orig_node_get_router(next_gw->orig_node);
222                 if (!router) {
223                         batadv_gw_deselect(bat_priv);
224                         goto out;
225                 }
226         }
227
228         if ((curr_gw) && (!next_gw)) {
229                 batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
230                            "Removing selected gateway - no gateway in range\n");
231                 batadv_throw_uevent(bat_priv, BATADV_UEV_GW, BATADV_UEV_DEL,
232                                     NULL);
233         } else if ((!curr_gw) && (next_gw)) {
234                 batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
235                            "Adding route to gateway %pM (gw_flags: %i, tq: %i)\n",
236                            next_gw->orig_node->orig,
237                            next_gw->orig_node->gw_flags, router->tq_avg);
238                 batadv_throw_uevent(bat_priv, BATADV_UEV_GW, BATADV_UEV_ADD,
239                                     gw_addr);
240         } else {
241                 batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
242                            "Changing route to gateway %pM (gw_flags: %i, tq: %i)\n",
243                            next_gw->orig_node->orig,
244                            next_gw->orig_node->gw_flags, router->tq_avg);
245                 batadv_throw_uevent(bat_priv, BATADV_UEV_GW, BATADV_UEV_CHANGE,
246                                     gw_addr);
247         }
248
249         batadv_gw_select(bat_priv, next_gw);
250
251 out:
252         if (curr_gw)
253                 batadv_gw_node_free_ref(curr_gw);
254         if (next_gw)
255                 batadv_gw_node_free_ref(next_gw);
256         if (router)
257                 batadv_neigh_node_free_ref(router);
258 }
259
260 void batadv_gw_check_election(struct batadv_priv *bat_priv,
261                               struct batadv_orig_node *orig_node)
262 {
263         struct batadv_orig_node *curr_gw_orig;
264         struct batadv_neigh_node *router_gw = NULL, *router_orig = NULL;
265         uint8_t gw_tq_avg, orig_tq_avg;
266
267         curr_gw_orig = batadv_gw_get_selected_orig(bat_priv);
268         if (!curr_gw_orig)
269                 goto deselect;
270
271         router_gw = batadv_orig_node_get_router(curr_gw_orig);
272         if (!router_gw)
273                 goto deselect;
274
275         /* this node already is the gateway */
276         if (curr_gw_orig == orig_node)
277                 goto out;
278
279         router_orig = batadv_orig_node_get_router(orig_node);
280         if (!router_orig)
281                 goto out;
282
283         gw_tq_avg = router_gw->tq_avg;
284         orig_tq_avg = router_orig->tq_avg;
285
286         /* the TQ value has to be better */
287         if (orig_tq_avg < gw_tq_avg)
288                 goto out;
289
290         /* if the routing class is greater than 3 the value tells us how much
291          * greater the TQ value of the new gateway must be
292          */
293         if ((atomic_read(&bat_priv->gw_sel_class) > 3) &&
294             (orig_tq_avg - gw_tq_avg < atomic_read(&bat_priv->gw_sel_class)))
295                 goto out;
296
297         batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
298                    "Restarting gateway selection: better gateway found (tq curr: %i, tq new: %i)\n",
299                    gw_tq_avg, orig_tq_avg);
300
301 deselect:
302         batadv_gw_deselect(bat_priv);
303 out:
304         if (curr_gw_orig)
305                 batadv_orig_node_free_ref(curr_gw_orig);
306         if (router_gw)
307                 batadv_neigh_node_free_ref(router_gw);
308         if (router_orig)
309                 batadv_neigh_node_free_ref(router_orig);
310
311         return;
312 }
313
314 static void batadv_gw_node_add(struct batadv_priv *bat_priv,
315                                struct batadv_orig_node *orig_node,
316                                uint8_t new_gwflags)
317 {
318         struct batadv_gw_node *gw_node;
319         int down, up;
320
321         gw_node = kzalloc(sizeof(*gw_node), GFP_ATOMIC);
322         if (!gw_node)
323                 return;
324
325         INIT_HLIST_NODE(&gw_node->list);
326         gw_node->orig_node = orig_node;
327         atomic_set(&gw_node->refcount, 1);
328
329         spin_lock_bh(&bat_priv->gw.list_lock);
330         hlist_add_head_rcu(&gw_node->list, &bat_priv->gw.list);
331         spin_unlock_bh(&bat_priv->gw.list_lock);
332
333         batadv_gw_bandwidth_to_kbit(new_gwflags, &down, &up);
334         batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
335                    "Found new gateway %pM -> gw_class: %i - %i%s/%i%s\n",
336                    orig_node->orig, new_gwflags,
337                    (down > 2048 ? down / 1024 : down),
338                    (down > 2048 ? "MBit" : "KBit"),
339                    (up > 2048 ? up / 1024 : up),
340                    (up > 2048 ? "MBit" : "KBit"));
341 }
342
343 void batadv_gw_node_update(struct batadv_priv *bat_priv,
344                            struct batadv_orig_node *orig_node,
345                            uint8_t new_gwflags)
346 {
347         struct hlist_node *node;
348         struct batadv_gw_node *gw_node, *curr_gw;
349
350         /* Note: We don't need a NULL check here, since curr_gw never gets
351          * dereferenced. If curr_gw is NULL we also should not exit as we may
352          * have this gateway in our list (duplication check!) even though we
353          * have no currently selected gateway.
354          */
355         curr_gw = batadv_gw_get_selected_gw_node(bat_priv);
356
357         rcu_read_lock();
358         hlist_for_each_entry_rcu(gw_node, node, &bat_priv->gw.list, list) {
359                 if (gw_node->orig_node != orig_node)
360                         continue;
361
362                 batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
363                            "Gateway class of originator %pM changed from %i to %i\n",
364                            orig_node->orig, gw_node->orig_node->gw_flags,
365                            new_gwflags);
366
367                 gw_node->deleted = 0;
368
369                 if (new_gwflags == BATADV_NO_FLAGS) {
370                         gw_node->deleted = jiffies;
371                         batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
372                                    "Gateway %pM removed from gateway list\n",
373                                    orig_node->orig);
374
375                         if (gw_node == curr_gw)
376                                 goto deselect;
377                 }
378
379                 goto unlock;
380         }
381
382         if (new_gwflags == BATADV_NO_FLAGS)
383                 goto unlock;
384
385         batadv_gw_node_add(bat_priv, orig_node, new_gwflags);
386         goto unlock;
387
388 deselect:
389         batadv_gw_deselect(bat_priv);
390 unlock:
391         rcu_read_unlock();
392
393         if (curr_gw)
394                 batadv_gw_node_free_ref(curr_gw);
395 }
396
397 void batadv_gw_node_delete(struct batadv_priv *bat_priv,
398                            struct batadv_orig_node *orig_node)
399 {
400         batadv_gw_node_update(bat_priv, orig_node, 0);
401 }
402
403 void batadv_gw_node_purge(struct batadv_priv *bat_priv)
404 {
405         struct batadv_gw_node *gw_node, *curr_gw;
406         struct hlist_node *node, *node_tmp;
407         unsigned long timeout = msecs_to_jiffies(2 * BATADV_PURGE_TIMEOUT);
408         int do_deselect = 0;
409
410         curr_gw = batadv_gw_get_selected_gw_node(bat_priv);
411
412         spin_lock_bh(&bat_priv->gw.list_lock);
413
414         hlist_for_each_entry_safe(gw_node, node, node_tmp,
415                                   &bat_priv->gw.list, list) {
416                 if (((!gw_node->deleted) ||
417                      (time_before(jiffies, gw_node->deleted + timeout))) &&
418                     atomic_read(&bat_priv->mesh_state) == BATADV_MESH_ACTIVE)
419                         continue;
420
421                 if (curr_gw == gw_node)
422                         do_deselect = 1;
423
424                 hlist_del_rcu(&gw_node->list);
425                 batadv_gw_node_free_ref(gw_node);
426         }
427
428         spin_unlock_bh(&bat_priv->gw.list_lock);
429
430         /* gw_deselect() needs to acquire the gw_list_lock */
431         if (do_deselect)
432                 batadv_gw_deselect(bat_priv);
433
434         if (curr_gw)
435                 batadv_gw_node_free_ref(curr_gw);
436 }
437
438 /* fails if orig_node has no router */
439 static int batadv_write_buffer_text(struct batadv_priv *bat_priv,
440                                     struct seq_file *seq,
441                                     const struct batadv_gw_node *gw_node)
442 {
443         struct batadv_gw_node *curr_gw;
444         struct batadv_neigh_node *router;
445         int down, up, ret = -1;
446
447         batadv_gw_bandwidth_to_kbit(gw_node->orig_node->gw_flags, &down, &up);
448
449         router = batadv_orig_node_get_router(gw_node->orig_node);
450         if (!router)
451                 goto out;
452
453         curr_gw = batadv_gw_get_selected_gw_node(bat_priv);
454
455         ret = seq_printf(seq, "%s %pM (%3i) %pM [%10s]: %3i - %i%s/%i%s\n",
456                          (curr_gw == gw_node ? "=>" : "  "),
457                          gw_node->orig_node->orig,
458                          router->tq_avg, router->addr,
459                          router->if_incoming->net_dev->name,
460                          gw_node->orig_node->gw_flags,
461                          (down > 2048 ? down / 1024 : down),
462                          (down > 2048 ? "MBit" : "KBit"),
463                          (up > 2048 ? up / 1024 : up),
464                          (up > 2048 ? "MBit" : "KBit"));
465
466         batadv_neigh_node_free_ref(router);
467         if (curr_gw)
468                 batadv_gw_node_free_ref(curr_gw);
469 out:
470         return ret;
471 }
472
473 int batadv_gw_client_seq_print_text(struct seq_file *seq, void *offset)
474 {
475         struct net_device *net_dev = (struct net_device *)seq->private;
476         struct batadv_priv *bat_priv = netdev_priv(net_dev);
477         struct batadv_hard_iface *primary_if;
478         struct batadv_gw_node *gw_node;
479         struct hlist_node *node;
480         int gw_count = 0;
481
482         primary_if = batadv_seq_print_text_primary_if_get(seq);
483         if (!primary_if)
484                 goto out;
485
486         seq_printf(seq,
487                    "      %-12s (%s/%i) %17s [%10s]: gw_class ... [B.A.T.M.A.N. adv %s, MainIF/MAC: %s/%pM (%s)]\n",
488                    "Gateway", "#", BATADV_TQ_MAX_VALUE, "Nexthop", "outgoingIF",
489                    BATADV_SOURCE_VERSION, primary_if->net_dev->name,
490                    primary_if->net_dev->dev_addr, net_dev->name);
491
492         rcu_read_lock();
493         hlist_for_each_entry_rcu(gw_node, node, &bat_priv->gw.list, list) {
494                 if (gw_node->deleted)
495                         continue;
496
497                 /* fails if orig_node has no router */
498                 if (batadv_write_buffer_text(bat_priv, seq, gw_node) < 0)
499                         continue;
500
501                 gw_count++;
502         }
503         rcu_read_unlock();
504
505         if (gw_count == 0)
506                 seq_printf(seq, "No gateways in range ...\n");
507
508 out:
509         if (primary_if)
510                 batadv_hardif_free_ref(primary_if);
511         return 0;
512 }
513
514 static bool batadv_is_type_dhcprequest(struct sk_buff *skb, int header_len)
515 {
516         int ret = false;
517         unsigned char *p;
518         int pkt_len;
519
520         if (skb_linearize(skb) < 0)
521                 goto out;
522
523         pkt_len = skb_headlen(skb);
524
525         if (pkt_len < header_len + BATADV_DHCP_OPTIONS_OFFSET + 1)
526                 goto out;
527
528         p = skb->data + header_len + BATADV_DHCP_OPTIONS_OFFSET;
529         pkt_len -= header_len + BATADV_DHCP_OPTIONS_OFFSET + 1;
530
531         /* Access the dhcp option lists. Each entry is made up by:
532          * - octet 1: option type
533          * - octet 2: option data len (only if type != 255 and 0)
534          * - octet 3: option data
535          */
536         while (*p != 255 && !ret) {
537                 /* p now points to the first octet: option type */
538                 if (*p == 53) {
539                         /* type 53 is the message type option.
540                          * Jump the len octet and go to the data octet
541                          */
542                         if (pkt_len < 2)
543                                 goto out;
544                         p += 2;
545
546                         /* check if the message type is what we need */
547                         if (*p == BATADV_DHCP_REQUEST)
548                                 ret = true;
549                         break;
550                 } else if (*p == 0) {
551                         /* option type 0 (padding), just go forward */
552                         if (pkt_len < 1)
553                                 goto out;
554                         pkt_len--;
555                         p++;
556                 } else {
557                         /* This is any other option. So we get the length... */
558                         if (pkt_len < 1)
559                                 goto out;
560                         pkt_len--;
561                         p++;
562
563                         /* ...and then we jump over the data */
564                         if (pkt_len < 1 + (*p))
565                                 goto out;
566                         pkt_len -= 1 + (*p);
567                         p += 1 + (*p);
568                 }
569         }
570 out:
571         return ret;
572 }
573
574 bool batadv_gw_is_dhcp_target(struct sk_buff *skb, unsigned int *header_len)
575 {
576         struct ethhdr *ethhdr;
577         struct iphdr *iphdr;
578         struct ipv6hdr *ipv6hdr;
579         struct udphdr *udphdr;
580
581         /* check for ethernet header */
582         if (!pskb_may_pull(skb, *header_len + ETH_HLEN))
583                 return false;
584         ethhdr = (struct ethhdr *)skb->data;
585         *header_len += ETH_HLEN;
586
587         /* check for initial vlan header */
588         if (ntohs(ethhdr->h_proto) == ETH_P_8021Q) {
589                 if (!pskb_may_pull(skb, *header_len + VLAN_HLEN))
590                         return false;
591                 ethhdr = (struct ethhdr *)(skb->data + VLAN_HLEN);
592                 *header_len += VLAN_HLEN;
593         }
594
595         /* check for ip header */
596         switch (ntohs(ethhdr->h_proto)) {
597         case ETH_P_IP:
598                 if (!pskb_may_pull(skb, *header_len + sizeof(*iphdr)))
599                         return false;
600                 iphdr = (struct iphdr *)(skb->data + *header_len);
601                 *header_len += iphdr->ihl * 4;
602
603                 /* check for udp header */
604                 if (iphdr->protocol != IPPROTO_UDP)
605                         return false;
606
607                 break;
608         case ETH_P_IPV6:
609                 if (!pskb_may_pull(skb, *header_len + sizeof(*ipv6hdr)))
610                         return false;
611                 ipv6hdr = (struct ipv6hdr *)(skb->data + *header_len);
612                 *header_len += sizeof(*ipv6hdr);
613
614                 /* check for udp header */
615                 if (ipv6hdr->nexthdr != IPPROTO_UDP)
616                         return false;
617
618                 break;
619         default:
620                 return false;
621         }
622
623         if (!pskb_may_pull(skb, *header_len + sizeof(*udphdr)))
624                 return false;
625         udphdr = (struct udphdr *)(skb->data + *header_len);
626         *header_len += sizeof(*udphdr);
627
628         /* check for bootp port */
629         if ((ntohs(ethhdr->h_proto) == ETH_P_IP) &&
630             (ntohs(udphdr->dest) != 67))
631                 return false;
632
633         if ((ntohs(ethhdr->h_proto) == ETH_P_IPV6) &&
634             (ntohs(udphdr->dest) != 547))
635                 return false;
636
637         return true;
638 }
639
640 bool batadv_gw_out_of_range(struct batadv_priv *bat_priv,
641                             struct sk_buff *skb, struct ethhdr *ethhdr)
642 {
643         struct batadv_neigh_node *neigh_curr = NULL, *neigh_old = NULL;
644         struct batadv_orig_node *orig_dst_node = NULL;
645         struct batadv_gw_node *curr_gw = NULL;
646         bool ret, out_of_range = false;
647         unsigned int header_len = 0;
648         uint8_t curr_tq_avg;
649
650         ret = batadv_gw_is_dhcp_target(skb, &header_len);
651         if (!ret)
652                 goto out;
653
654         orig_dst_node = batadv_transtable_search(bat_priv, ethhdr->h_source,
655                                                  ethhdr->h_dest);
656         if (!orig_dst_node)
657                 goto out;
658
659         if (!orig_dst_node->gw_flags)
660                 goto out;
661
662         ret = batadv_is_type_dhcprequest(skb, header_len);
663         if (!ret)
664                 goto out;
665
666         switch (atomic_read(&bat_priv->gw_mode)) {
667         case BATADV_GW_MODE_SERVER:
668                 /* If we are a GW then we are our best GW. We can artificially
669                  * set the tq towards ourself as the maximum value
670                  */
671                 curr_tq_avg = BATADV_TQ_MAX_VALUE;
672                 break;
673         case BATADV_GW_MODE_CLIENT:
674                 curr_gw = batadv_gw_get_selected_gw_node(bat_priv);
675                 if (!curr_gw)
676                         goto out;
677
678                 /* packet is going to our gateway */
679                 if (curr_gw->orig_node == orig_dst_node)
680                         goto out;
681
682                 /* If the dhcp packet has been sent to a different gw,
683                  * we have to evaluate whether the old gw is still
684                  * reliable enough
685                  */
686                 neigh_curr = batadv_find_router(bat_priv, curr_gw->orig_node,
687                                                 NULL);
688                 if (!neigh_curr)
689                         goto out;
690
691                 curr_tq_avg = neigh_curr->tq_avg;
692                 break;
693         case BATADV_GW_MODE_OFF:
694         default:
695                 goto out;
696         }
697
698         neigh_old = batadv_find_router(bat_priv, orig_dst_node, NULL);
699         if (!neigh_old)
700                 goto out;
701
702         if (curr_tq_avg - neigh_old->tq_avg > BATADV_GW_THRESHOLD)
703                 out_of_range = true;
704
705 out:
706         if (orig_dst_node)
707                 batadv_orig_node_free_ref(orig_dst_node);
708         if (curr_gw)
709                 batadv_gw_node_free_ref(curr_gw);
710         if (neigh_old)
711                 batadv_neigh_node_free_ref(neigh_old);
712         if (neigh_curr)
713                 batadv_neigh_node_free_ref(neigh_curr);
714         return out_of_range;
715 }