net/batman-adv/gateway_client.c

   1 /*
   2  * Copyright (C) 2009-2012 B.A.T.M.A.N. contributors:
   3  *
   4  * Marek Lindner
   5  *
   6  * This program is free software; you can redistribute it and/or
   7  * modify it under the terms of version 2 of the GNU General Public
   8  * License as published by the Free Software Foundation.
   9  *
  10  * This program is distributed in the hope that it will be useful, but
  11  * WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  13  * General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License
  16  * along with this program; if not, write to the Free Software
  17  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
  18  * 02110-1301, USA
  19  *
  20  */
  21
  22 #include "main.h"
  23 #include "bat_sysfs.h"
  24 #include "gateway_client.h"
  25 #include "gateway_common.h"
  26 #include "hard-interface.h"
  27 #include "originator.h"
  28 #include "translation-table.h"
  29 #include "routing.h"
  30 #include <linux/ip.h>
  31 #include <linux/ipv6.h>
  32 #include <linux/udp.h>
  33 #include <linux/if_vlan.h>
  34
  35 /* This is the offset of the options field in a dhcp packet starting at
  36  * the beginning of the dhcp header */
  37 #define DHCP_OPTIONS_OFFSET 240
  38 #define DHCP_REQUEST 3
  39
  40 static void gw_node_free_ref(struct gw_node *gw_node)
  41 {
  42         if (atomic_dec_and_test(&gw_node->refcount))
  43                 kfree_rcu(gw_node, rcu);
  44 }
  45
  46 static struct gw_node *gw_get_selected_gw_node(struct bat_priv *bat_priv)
  47 {
  48         struct gw_node *gw_node;
  49
  50         rcu_read_lock();
  51         gw_node = rcu_dereference(bat_priv->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 orig_node *batadv_gw_get_selected_orig(struct bat_priv *bat_priv)
  64 {
  65         struct gw_node *gw_node;
  66         struct orig_node *orig_node = NULL;
  67
  68         gw_node = gw_get_selected_gw_node(bat_priv);
  69         if (!gw_node)
  70                 goto out;
  71
  72         rcu_read_lock();
  73         orig_node = gw_node->orig_node;
  74         if (!orig_node)
  75                 goto unlock;
  76
  77         if (!atomic_inc_not_zero(&orig_node->refcount))
  78                 orig_node = NULL;
  79
  80 unlock:
  81         rcu_read_unlock();
  82 out:
  83         if (gw_node)
  84                 gw_node_free_ref(gw_node);
  85         return orig_node;
  86 }
  87
  88 static void gw_select(struct bat_priv *bat_priv, struct gw_node *new_gw_node)
  89 {
  90         struct gw_node *curr_gw_node;
  91
  92         spin_lock_bh(&bat_priv->gw_list_lock);
  93
  94         if (new_gw_node && !atomic_inc_not_zero(&new_gw_node->refcount))
  95                 new_gw_node = NULL;
  96
  97         curr_gw_node = rcu_dereference_protected(bat_priv->curr_gw, 1);
  98         rcu_assign_pointer(bat_priv->curr_gw, new_gw_node);
  99
 100         if (curr_gw_node)
 101                 gw_node_free_ref(curr_gw_node);
 102
 103         spin_unlock_bh(&bat_priv->gw_list_lock);
 104 }
 105
 106 void batadv_gw_deselect(struct bat_priv *bat_priv)
 107 {
 108         atomic_set(&bat_priv->gw_reselect, 1);
 109 }
 110
 111 static struct gw_node *gw_get_best_gw_node(struct bat_priv *bat_priv)
 112 {
 113         struct neigh_node *router;
 114         struct hlist_node *node;
 115         struct gw_node *gw_node, *curr_gw = NULL;
 116         uint32_t max_gw_factor = 0, tmp_gw_factor = 0;
 117         uint8_t max_tq = 0;
 118         int down, up;
 119
 120         rcu_read_lock();
 121         hlist_for_each_entry_rcu(gw_node, node, &bat_priv->gw_list, list) {
 122                 if (gw_node->deleted)
 123                         continue;
 124
 125                 router = orig_node_get_router(gw_node->orig_node);
 126                 if (!router)
 127                         continue;
 128
 129                 if (!atomic_inc_not_zero(&gw_node->refcount))
 130                         goto next;
 131
 132                 switch (atomic_read(&bat_priv->gw_sel_class)) {
 133                 case 1: /* fast connection */
 134                         gw_bandwidth_to_kbit(gw_node->orig_node->gw_flags,
 135                                              &down, &up);
 136
 137                         tmp_gw_factor = (router->tq_avg * router->tq_avg *
 138                                          down * 100 * 100) /
 139                                          (TQ_LOCAL_WINDOW_SIZE *
 140                                          TQ_LOCAL_WINDOW_SIZE * 64);
 141
 142                         if ((tmp_gw_factor > max_gw_factor) ||
 143                             ((tmp_gw_factor == max_gw_factor) &&
 144                              (router->tq_avg > max_tq))) {
 145                                 if (curr_gw)
 146                                         gw_node_free_ref(curr_gw);
 147                                 curr_gw = gw_node;
 148                                 atomic_inc(&curr_gw->refcount);
 149                         }
 150                         break;
 151
 152                 default: /**
 153                           * 2:  stable connection (use best statistic)
 154                           * 3:  fast-switch (use best statistic but change as
 155                           *     soon as a better gateway appears)
 156                           * XX: late-switch (use best statistic but change as
 157                           *     soon as a better gateway appears which has
 158                           *     $routing_class more tq points)
 159                           **/
 160                         if (router->tq_avg > max_tq) {
 161                                 if (curr_gw)
 162                                         gw_node_free_ref(curr_gw);
 163                                 curr_gw = gw_node;
 164                                 atomic_inc(&curr_gw->refcount);
 165                         }
 166                         break;
 167                 }
 168
 169                 if (router->tq_avg > max_tq)
 170                         max_tq = router->tq_avg;
 171
 172                 if (tmp_gw_factor > max_gw_factor)
 173                         max_gw_factor = tmp_gw_factor;
 174
 175                 gw_node_free_ref(gw_node);
 176
 177 next:
 178                 neigh_node_free_ref(router);
 179         }
 180         rcu_read_unlock();
 181
 182         return curr_gw;
 183 }
 184
 185 void batadv_gw_election(struct bat_priv *bat_priv)
 186 {
 187         struct gw_node *curr_gw = NULL, *next_gw = NULL;
 188         struct neigh_node *router = NULL;
 189         char gw_addr[18] = { '\0' };
 190
 191         /**
 192          * The batman daemon checks here if we already passed a full originator
 193          * cycle in order to make sure we don't choose the first gateway we
 194          * hear about. This check is based on the daemon's uptime which we
 195          * don't have.
 196          **/
 197         if (atomic_read(&bat_priv->gw_mode) != GW_MODE_CLIENT)
 198                 goto out;
 199
 200         if (!atomic_dec_not_zero(&bat_priv->gw_reselect))
 201                 goto out;
 202
 203         curr_gw = gw_get_selected_gw_node(bat_priv);
 204
 205         next_gw = gw_get_best_gw_node(bat_priv);
 206
 207         if (curr_gw == next_gw)
 208                 goto out;
 209
 210         if (next_gw) {
 211                 sprintf(gw_addr, "%pM", next_gw->orig_node->orig);
 212
 213                 router = orig_node_get_router(next_gw->orig_node);
 214                 if (!router) {
 215                         batadv_gw_deselect(bat_priv);
 216                         goto out;
 217                 }
 218         }
 219
 220         if ((curr_gw) && (!next_gw)) {
 221                 bat_dbg(DBG_BATMAN, bat_priv,
 222                         "Removing selected gateway - no gateway in range\n");
 223                 batadv_throw_uevent(bat_priv, UEV_GW, UEV_DEL, NULL);
 224         } else if ((!curr_gw) && (next_gw)) {
 225                 bat_dbg(DBG_BATMAN, bat_priv,
 226                         "Adding route to gateway %pM (gw_flags: %i, tq: %i)\n",
 227                         next_gw->orig_node->orig, next_gw->orig_node->gw_flags,
 228                         router->tq_avg);
 229                 batadv_throw_uevent(bat_priv, UEV_GW, UEV_ADD, gw_addr);
 230         } else {
 231                 bat_dbg(DBG_BATMAN, bat_priv,
 232                         "Changing route to gateway %pM (gw_flags: %i, tq: %i)\n",
 233                         next_gw->orig_node->orig, next_gw->orig_node->gw_flags,
 234                         router->tq_avg);
 235                 batadv_throw_uevent(bat_priv, UEV_GW, UEV_CHANGE, gw_addr);
 236         }
 237
 238         gw_select(bat_priv, next_gw);
 239
 240 out:
 241         if (curr_gw)
 242                 gw_node_free_ref(curr_gw);
 243         if (next_gw)
 244                 gw_node_free_ref(next_gw);
 245         if (router)
 246                 neigh_node_free_ref(router);
 247 }
 248
 249 void batadv_gw_check_election(struct bat_priv *bat_priv,
 250                               struct orig_node *orig_node)
 251 {
 252         struct orig_node *curr_gw_orig;
 253         struct neigh_node *router_gw = NULL, *router_orig = NULL;
 254         uint8_t gw_tq_avg, orig_tq_avg;
 255
 256         curr_gw_orig = batadv_gw_get_selected_orig(bat_priv);
 257         if (!curr_gw_orig)
 258                 goto deselect;
 259
 260         router_gw = orig_node_get_router(curr_gw_orig);
 261         if (!router_gw)
 262                 goto deselect;
 263
 264         /* this node already is the gateway */
 265         if (curr_gw_orig == orig_node)
 266                 goto out;
 267
 268         router_orig = orig_node_get_router(orig_node);
 269         if (!router_orig)
 270                 goto out;
 271
 272         gw_tq_avg = router_gw->tq_avg;
 273         orig_tq_avg = router_orig->tq_avg;
 274
 275         /* the TQ value has to be better */
 276         if (orig_tq_avg < gw_tq_avg)
 277                 goto out;
 278
 279         /**
 280          * if the routing class is greater than 3 the value tells us how much
 281          * greater the TQ value of the new gateway must be
 282          **/
 283         if ((atomic_read(&bat_priv->gw_sel_class) > 3) &&
 284             (orig_tq_avg - gw_tq_avg < atomic_read(&bat_priv->gw_sel_class)))
 285                 goto out;
 286
 287         bat_dbg(DBG_BATMAN, bat_priv,
 288                 "Restarting gateway selection: better gateway found (tq curr: %i, tq new: %i)\n",
 289                 gw_tq_avg, orig_tq_avg);
 290
 291 deselect:
 292         batadv_gw_deselect(bat_priv);
 293 out:
 294         if (curr_gw_orig)
 295                 orig_node_free_ref(curr_gw_orig);
 296         if (router_gw)
 297                 neigh_node_free_ref(router_gw);
 298         if (router_orig)
 299                 neigh_node_free_ref(router_orig);
 300
 301         return;
 302 }
 303
 304 static void gw_node_add(struct bat_priv *bat_priv,
 305                         struct orig_node *orig_node, uint8_t new_gwflags)
 306 {
 307         struct gw_node *gw_node;
 308         int down, up;
 309
 310         gw_node = kzalloc(sizeof(*gw_node), GFP_ATOMIC);
 311         if (!gw_node)
 312                 return;
 313
 314         INIT_HLIST_NODE(&gw_node->list);
 315         gw_node->orig_node = orig_node;
 316         atomic_set(&gw_node->refcount, 1);
 317
 318         spin_lock_bh(&bat_priv->gw_list_lock);
 319         hlist_add_head_rcu(&gw_node->list, &bat_priv->gw_list);
 320         spin_unlock_bh(&bat_priv->gw_list_lock);
 321
 322         gw_bandwidth_to_kbit(new_gwflags, &down, &up);
 323         bat_dbg(DBG_BATMAN, bat_priv,
 324                 "Found new gateway %pM -> gw_class: %i - %i%s/%i%s\n",
 325                 orig_node->orig, new_gwflags,
 326                 (down > 2048 ? down / 1024 : down),
 327                 (down > 2048 ? "MBit" : "KBit"),
 328                 (up > 2048 ? up / 1024 : up),
 329                 (up > 2048 ? "MBit" : "KBit"));
 330 }
 331
 332 void batadv_gw_node_update(struct bat_priv *bat_priv,
 333                            struct orig_node *orig_node, uint8_t new_gwflags)
 334 {
 335         struct hlist_node *node;
 336         struct gw_node *gw_node, *curr_gw;
 337
 338         /**
 339          * Note: We don't need a NULL check here, since curr_gw never gets
 340          * dereferenced. If curr_gw is NULL we also should not exit as we may
 341          * have this gateway in our list (duplication check!) even though we
 342          * have no currently selected gateway.
 343          */
 344         curr_gw = gw_get_selected_gw_node(bat_priv);
 345
 346         rcu_read_lock();
 347         hlist_for_each_entry_rcu(gw_node, node, &bat_priv->gw_list, list) {
 348                 if (gw_node->orig_node != orig_node)
 349                         continue;
 350
 351                 bat_dbg(DBG_BATMAN, bat_priv,
 352                         "Gateway class of originator %pM changed from %i to %i\n",
 353                         orig_node->orig, gw_node->orig_node->gw_flags,
 354                         new_gwflags);
 355
 356                 gw_node->deleted = 0;
 357
 358                 if (new_gwflags == NO_FLAGS) {
 359                         gw_node->deleted = jiffies;
 360                         bat_dbg(DBG_BATMAN, bat_priv,
 361                                 "Gateway %pM removed from gateway list\n",
 362                                 orig_node->orig);
 363
 364                         if (gw_node == curr_gw)
 365                                 goto deselect;
 366                 }
 367
 368                 goto unlock;
 369         }
 370
 371         if (new_gwflags == NO_FLAGS)
 372                 goto unlock;
 373
 374         gw_node_add(bat_priv, orig_node, new_gwflags);
 375         goto unlock;
 376
 377 deselect:
 378         batadv_gw_deselect(bat_priv);
 379 unlock:
 380         rcu_read_unlock();
 381
 382         if (curr_gw)
 383                 gw_node_free_ref(curr_gw);
 384 }
 385
 386 void batadv_gw_node_delete(struct bat_priv *bat_priv,
 387                            struct orig_node *orig_node)
 388 {
 389         batadv_gw_node_update(bat_priv, orig_node, 0);
 390 }
 391
 392 void batadv_gw_node_purge(struct bat_priv *bat_priv)
 393 {
 394         struct gw_node *gw_node, *curr_gw;
 395         struct hlist_node *node, *node_tmp;
 396         unsigned long timeout = msecs_to_jiffies(2 * PURGE_TIMEOUT);
 397         int do_deselect = 0;
 398
 399         curr_gw = gw_get_selected_gw_node(bat_priv);
 400
 401         spin_lock_bh(&bat_priv->gw_list_lock);
 402
 403         hlist_for_each_entry_safe(gw_node, node, node_tmp,
 404                                   &bat_priv->gw_list, list) {
 405                 if (((!gw_node->deleted) ||
 406                      (time_before(jiffies, gw_node->deleted + timeout))) &&
 407                     atomic_read(&bat_priv->mesh_state) == MESH_ACTIVE)
 408                         continue;
 409
 410                 if (curr_gw == gw_node)
 411                         do_deselect = 1;
 412
 413                 hlist_del_rcu(&gw_node->list);
 414                 gw_node_free_ref(gw_node);
 415         }
 416
 417         spin_unlock_bh(&bat_priv->gw_list_lock);
 418
 419         /* gw_deselect() needs to acquire the gw_list_lock */
 420         if (do_deselect)
 421                 batadv_gw_deselect(bat_priv);
 422
 423         if (curr_gw)
 424                 gw_node_free_ref(curr_gw);
 425 }
 426
 427 /**
 428  * fails if orig_node has no router
 429  */
 430 static int _write_buffer_text(struct bat_priv *bat_priv, struct seq_file *seq,
 431                               const struct gw_node *gw_node)
 432 {
 433         struct gw_node *curr_gw;
 434         struct neigh_node *router;
 435         int down, up, ret = -1;
 436
 437         gw_bandwidth_to_kbit(gw_node->orig_node->gw_flags, &down, &up);
 438
 439         router = orig_node_get_router(gw_node->orig_node);
 440         if (!router)
 441                 goto out;
 442
 443         curr_gw = gw_get_selected_gw_node(bat_priv);
 444
 445         ret = seq_printf(seq, "%s %pM (%3i) %pM [%10s]: %3i - %i%s/%i%s\n",
 446                          (curr_gw == gw_node ? "=>" : "  "),
 447                          gw_node->orig_node->orig,
 448                          router->tq_avg, router->addr,
 449                          router->if_incoming->net_dev->name,
 450                          gw_node->orig_node->gw_flags,
 451                          (down > 2048 ? down / 1024 : down),
 452                          (down > 2048 ? "MBit" : "KBit"),
 453                          (up > 2048 ? up / 1024 : up),
 454                          (up > 2048 ? "MBit" : "KBit"));
 455
 456         neigh_node_free_ref(router);
 457         if (curr_gw)
 458                 gw_node_free_ref(curr_gw);
 459 out:
 460         return ret;
 461 }
 462
 463 int batadv_gw_client_seq_print_text(struct seq_file *seq, void *offset)
 464 {
 465         struct net_device *net_dev = (struct net_device *)seq->private;
 466         struct bat_priv *bat_priv = netdev_priv(net_dev);
 467         struct hard_iface *primary_if;
 468         struct gw_node *gw_node;
 469         struct hlist_node *node;
 470         int gw_count = 0, ret = 0;
 471
 472         primary_if = primary_if_get_selected(bat_priv);
 473         if (!primary_if) {
 474                 ret = seq_printf(seq,
 475                                  "BATMAN mesh %s disabled - please specify interfaces to enable it\n",
 476                                  net_dev->name);
 477                 goto out;
 478         }
 479
 480         if (primary_if->if_status != IF_ACTIVE) {
 481                 ret = seq_printf(seq,
 482                                  "BATMAN mesh %s disabled - primary interface not active\n",
 483                                  net_dev->name);
 484                 goto out;
 485         }
 486
 487         seq_printf(seq,
 488                    "      %-12s (%s/%i) %17s [%10s]: gw_class ... [B.A.T.M.A.N. adv %s, MainIF/MAC: %s/%pM (%s)]\n",
 489                    "Gateway", "#", TQ_MAX_VALUE, "Nexthop", "outgoingIF",
 490                    SOURCE_VERSION, primary_if->net_dev->name,
 491                    primary_if->net_dev->dev_addr, net_dev->name);
 492
 493         rcu_read_lock();
 494         hlist_for_each_entry_rcu(gw_node, node, &bat_priv->gw_list, list) {
 495                 if (gw_node->deleted)
 496                         continue;
 497
 498                 /* fails if orig_node has no router */
 499                 if (_write_buffer_text(bat_priv, seq, gw_node) < 0)
 500                         continue;
 501
 502                 gw_count++;
 503         }
 504         rcu_read_unlock();
 505
 506         if (gw_count == 0)
 507                 seq_printf(seq, "No gateways in range ...\n");
 508
 509 out:
 510         if (primary_if)
 511                 hardif_free_ref(primary_if);
 512         return ret;
 513 }
 514
 515 static bool is_type_dhcprequest(struct sk_buff *skb, int header_len)
 516 {
 517         int ret = false;
 518         unsigned char *p;
 519         int pkt_len;
 520
 521         if (skb_linearize(skb) < 0)
 522                 goto out;
 523
 524         pkt_len = skb_headlen(skb);
 525
 526         if (pkt_len < header_len + DHCP_OPTIONS_OFFSET + 1)
 527                 goto out;
 528
 529         p = skb->data + header_len + DHCP_OPTIONS_OFFSET;
 530         pkt_len -= header_len + DHCP_OPTIONS_OFFSET + 1;
 531
 532         /* Access the dhcp option lists. Each entry is made up by:
 533          * - octet 1: option type
 534          * - octet 2: option data len (only if type != 255 and 0)
 535          * - octet 3: option data */
 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                         if (pkt_len < 2)
 542                                 goto out;
 543                         p += 2;
 544
 545                         /* check if the message type is what we need */
 546                         if (*p == DHCP_REQUEST)
 547                                 ret = true;
 548                         break;
 549                 } else if (*p == 0) {
 550                         /* option type 0 (padding), just go forward */
 551                         if (pkt_len < 1)
 552                                 goto out;
 553                         pkt_len--;
 554                         p++;
 555                 } else {
 556                         /* This is any other option. So we get the length... */
 557                         if (pkt_len < 1)
 558                                 goto out;
 559                         pkt_len--;
 560                         p++;
 561
 562                         /* ...and then we jump over the data */
 563                         if (pkt_len < 1 + (*p))
 564                                 goto out;
 565                         pkt_len -= 1 + (*p);
 566                         p += 1 + (*p);
 567                 }
 568         }
 569 out:
 570         return ret;
 571 }
 572
 573 bool batadv_gw_is_dhcp_target(struct sk_buff *skb, unsigned int *header_len)
 574 {
 575         struct ethhdr *ethhdr;
 576         struct iphdr *iphdr;
 577         struct ipv6hdr *ipv6hdr;
 578         struct udphdr *udphdr;
 579
 580         /* check for ethernet header */
 581         if (!pskb_may_pull(skb, *header_len + ETH_HLEN))
 582                 return false;
 583         ethhdr = (struct ethhdr *)skb->data;
 584         *header_len += ETH_HLEN;
 585
 586         /* check for initial vlan header */
 587         if (ntohs(ethhdr->h_proto) == ETH_P_8021Q) {
 588                 if (!pskb_may_pull(skb, *header_len + VLAN_HLEN))
 589                         return false;
 590                 ethhdr = (struct ethhdr *)(skb->data + VLAN_HLEN);
 591                 *header_len += VLAN_HLEN;
 592         }
 593
 594         /* check for ip header */
 595         switch (ntohs(ethhdr->h_proto)) {
 596         case ETH_P_IP:
 597                 if (!pskb_may_pull(skb, *header_len + sizeof(*iphdr)))
 598                         return false;
 599                 iphdr = (struct iphdr *)(skb->data + *header_len);
 600                 *header_len += iphdr->ihl * 4;
 601
 602                 /* check for udp header */
 603                 if (iphdr->protocol != IPPROTO_UDP)
 604                         return false;
 605
 606                 break;
 607         case ETH_P_IPV6:
 608                 if (!pskb_may_pull(skb, *header_len + sizeof(*ipv6hdr)))
 609                         return false;
 610                 ipv6hdr = (struct ipv6hdr *)(skb->data + *header_len);
 611                 *header_len += sizeof(*ipv6hdr);
 612
 613                 /* check for udp header */
 614                 if (ipv6hdr->nexthdr != IPPROTO_UDP)
 615                         return false;
 616
 617                 break;
 618         default:
 619                 return false;
 620         }
 621
 622         if (!pskb_may_pull(skb, *header_len + sizeof(*udphdr)))
 623                 return false;
 624         udphdr = (struct udphdr *)(skb->data + *header_len);
 625         *header_len += sizeof(*udphdr);
 626
 627         /* check for bootp port */
 628         if ((ntohs(ethhdr->h_proto) == ETH_P_IP) &&
 629             (ntohs(udphdr->dest) != 67))
 630                 return false;
 631
 632         if ((ntohs(ethhdr->h_proto) == ETH_P_IPV6) &&
 633             (ntohs(udphdr->dest) != 547))
 634                 return false;
 635
 636         return true;
 637 }
 638
 639 bool batadv_gw_out_of_range(struct bat_priv *bat_priv,
 640                             struct sk_buff *skb, struct ethhdr *ethhdr)
 641 {
 642         struct neigh_node *neigh_curr = NULL, *neigh_old = NULL;
 643         struct orig_node *orig_dst_node = NULL;
 644         struct gw_node *curr_gw = NULL;
 645         bool ret, out_of_range = false;
 646         unsigned int header_len = 0;
 647         uint8_t curr_tq_avg;
 648
 649         ret = batadv_gw_is_dhcp_target(skb, &header_len);
 650         if (!ret)
 651                 goto out;
 652
 653         orig_dst_node = transtable_search(bat_priv, ethhdr->h_source,
 654                                           ethhdr->h_dest);
 655         if (!orig_dst_node)
 656                 goto out;
 657
 658         if (!orig_dst_node->gw_flags)
 659                 goto out;
 660
 661         ret = is_type_dhcprequest(skb, header_len);
 662         if (!ret)
 663                 goto out;
 664
 665         switch (atomic_read(&bat_priv->gw_mode)) {
 666         case GW_MODE_SERVER:
 667                 /* If we are a GW then we are our best GW. We can artificially
 668                  * set the tq towards ourself as the maximum value */
 669                 curr_tq_avg = TQ_MAX_VALUE;
 670                 break;
 671         case GW_MODE_CLIENT:
 672                 curr_gw = gw_get_selected_gw_node(bat_priv);
 673                 if (!curr_gw)
 674                         goto out;
 675
 676                 /* packet is going to our gateway */
 677                 if (curr_gw->orig_node == orig_dst_node)
 678                         goto out;
 679
 680                 /* If the dhcp packet has been sent to a different gw,
 681                  * we have to evaluate whether the old gw is still
 682                  * reliable enough */
 683                 neigh_curr = find_router(bat_priv, curr_gw->orig_node, NULL);
 684                 if (!neigh_curr)
 685                         goto out;
 686
 687                 curr_tq_avg = neigh_curr->tq_avg;
 688                 break;
 689         case GW_MODE_OFF:
 690         default:
 691                 goto out;
 692         }
 693
 694         neigh_old = find_router(bat_priv, orig_dst_node, NULL);
 695         if (!neigh_old)
 696                 goto out;
 697
 698         if (curr_tq_avg - neigh_old->tq_avg > GW_THRESHOLD)
 699                 out_of_range = true;
 700
 701 out:
 702         if (orig_dst_node)
 703                 orig_node_free_ref(orig_dst_node);
 704         if (curr_gw)
 705                 gw_node_free_ref(curr_gw);
 706         if (neigh_old)
 707                 neigh_node_free_ref(neigh_old);
 708         if (neigh_curr)
 709                 neigh_node_free_ref(neigh_curr);
 710         return out_of_range;
 711 }