net/batman-adv/gateway_client.c

   1 /*
   2  * Copyright (C) 2009-2011 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 *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 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 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                         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                 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,
 228                         next_gw->orig_node->gw_flags,
 229                         router->tq_avg);
 230                 throw_uevent(bat_priv, UEV_GW, UEV_ADD, gw_addr);
 231         } else {
 232                 bat_dbg(DBG_BATMAN, bat_priv,
 233                         "Changing route to gateway %pM "
 234                         "(gw_flags: %i, tq: %i)\n",
 235                         next_gw->orig_node->orig,
 236                         next_gw->orig_node->gw_flags,
 237                         router->tq_avg);
 238                 throw_uevent(bat_priv, UEV_GW, UEV_CHANGE, gw_addr);
 239         }
 240
 241         gw_select(bat_priv, next_gw);
 242
 243 out:
 244         if (curr_gw)
 245                 gw_node_free_ref(curr_gw);
 246         if (next_gw)
 247                 gw_node_free_ref(next_gw);
 248         if (router)
 249                 neigh_node_free_ref(router);
 250 }
 251
 252 void gw_check_election(struct bat_priv *bat_priv, struct orig_node *orig_node)
 253 {
 254         struct orig_node *curr_gw_orig;
 255         struct neigh_node *router_gw = NULL, *router_orig = NULL;
 256         uint8_t gw_tq_avg, orig_tq_avg;
 257
 258         curr_gw_orig = gw_get_selected_orig(bat_priv);
 259         if (!curr_gw_orig)
 260                 goto deselect;
 261
 262         router_gw = orig_node_get_router(curr_gw_orig);
 263         if (!router_gw)
 264                 goto deselect;
 265
 266         /* this node already is the gateway */
 267         if (curr_gw_orig == orig_node)
 268                 goto out;
 269
 270         router_orig = orig_node_get_router(orig_node);
 271         if (!router_orig)
 272                 goto out;
 273
 274         gw_tq_avg = router_gw->tq_avg;
 275         orig_tq_avg = router_orig->tq_avg;
 276
 277         /* the TQ value has to be better */
 278         if (orig_tq_avg < gw_tq_avg)
 279                 goto out;
 280
 281         /**
 282          * if the routing class is greater than 3 the value tells us how much
 283          * greater the TQ value of the new gateway must be
 284          **/
 285         if ((atomic_read(&bat_priv->gw_sel_class) > 3) &&
 286             (orig_tq_avg - gw_tq_avg < atomic_read(&bat_priv->gw_sel_class)))
 287                 goto out;
 288
 289         bat_dbg(DBG_BATMAN, bat_priv,
 290                 "Restarting gateway selection: better gateway found (tq curr: "
 291                 "%i, tq new: %i)\n",
 292                 gw_tq_avg, orig_tq_avg);
 293
 294 deselect:
 295         gw_deselect(bat_priv);
 296 out:
 297         if (curr_gw_orig)
 298                 orig_node_free_ref(curr_gw_orig);
 299         if (router_gw)
 300                 neigh_node_free_ref(router_gw);
 301         if (router_orig)
 302                 neigh_node_free_ref(router_orig);
 303
 304         return;
 305 }
 306
 307 static void gw_node_add(struct bat_priv *bat_priv,
 308                         struct orig_node *orig_node, uint8_t new_gwflags)
 309 {
 310         struct gw_node *gw_node;
 311         int down, up;
 312
 313         gw_node = kzalloc(sizeof(*gw_node), GFP_ATOMIC);
 314         if (!gw_node)
 315                 return;
 316
 317         INIT_HLIST_NODE(&gw_node->list);
 318         gw_node->orig_node = orig_node;
 319         atomic_set(&gw_node->refcount, 1);
 320
 321         spin_lock_bh(&bat_priv->gw_list_lock);
 322         hlist_add_head_rcu(&gw_node->list, &bat_priv->gw_list);
 323         spin_unlock_bh(&bat_priv->gw_list_lock);
 324
 325         gw_bandwidth_to_kbit(new_gwflags, &down, &up);
 326         bat_dbg(DBG_BATMAN, bat_priv,
 327                 "Found new gateway %pM -> gw_class: %i - %i%s/%i%s\n",
 328                 orig_node->orig, new_gwflags,
 329                 (down > 2048 ? down / 1024 : down),
 330                 (down > 2048 ? "MBit" : "KBit"),
 331                 (up > 2048 ? up / 1024 : up),
 332                 (up > 2048 ? "MBit" : "KBit"));
 333 }
 334
 335 void gw_node_update(struct bat_priv *bat_priv,
 336                     struct orig_node *orig_node, uint8_t new_gwflags)
 337 {
 338         struct hlist_node *node;
 339         struct gw_node *gw_node, *curr_gw;
 340
 341         /**
 342          * Note: We don't need a NULL check here, since curr_gw never gets
 343          * dereferenced. If curr_gw is NULL we also should not exit as we may
 344          * have this gateway in our list (duplication check!) even though we
 345          * have no currently selected gateway.
 346          */
 347         curr_gw = gw_get_selected_gw_node(bat_priv);
 348
 349         rcu_read_lock();
 350         hlist_for_each_entry_rcu(gw_node, node, &bat_priv->gw_list, list) {
 351                 if (gw_node->orig_node != orig_node)
 352                         continue;
 353
 354                 bat_dbg(DBG_BATMAN, bat_priv,
 355                         "Gateway class of originator %pM changed from "
 356                         "%i to %i\n",
 357                         orig_node->orig, gw_node->orig_node->gw_flags,
 358                         new_gwflags);
 359
 360                 gw_node->deleted = 0;
 361
 362                 if (new_gwflags == NO_FLAGS) {
 363                         gw_node->deleted = jiffies;
 364                         bat_dbg(DBG_BATMAN, bat_priv,
 365                                 "Gateway %pM removed from gateway list\n",
 366                                 orig_node->orig);
 367
 368                         if (gw_node == curr_gw)
 369                                 goto deselect;
 370                 }
 371
 372                 goto unlock;
 373         }
 374
 375         if (new_gwflags == NO_FLAGS)
 376                 goto unlock;
 377
 378         gw_node_add(bat_priv, orig_node, new_gwflags);
 379         goto unlock;
 380
 381 deselect:
 382         gw_deselect(bat_priv);
 383 unlock:
 384         rcu_read_unlock();
 385
 386         if (curr_gw)
 387                 gw_node_free_ref(curr_gw);
 388 }
 389
 390 void gw_node_delete(struct bat_priv *bat_priv, struct orig_node *orig_node)
 391 {
 392         gw_node_update(bat_priv, orig_node, 0);
 393 }
 394
 395 void gw_node_purge(struct bat_priv *bat_priv)
 396 {
 397         struct gw_node *gw_node, *curr_gw;
 398         struct hlist_node *node, *node_tmp;
 399         unsigned long timeout = 2 * PURGE_TIMEOUT * HZ;
 400         int do_deselect = 0;
 401
 402         curr_gw = gw_get_selected_gw_node(bat_priv);
 403
 404         spin_lock_bh(&bat_priv->gw_list_lock);
 405
 406         hlist_for_each_entry_safe(gw_node, node, node_tmp,
 407                                   &bat_priv->gw_list, list) {
 408                 if (((!gw_node->deleted) ||
 409                      (time_before(jiffies, gw_node->deleted + timeout))) &&
 410                     atomic_read(&bat_priv->mesh_state) == MESH_ACTIVE)
 411                         continue;
 412
 413                 if (curr_gw == gw_node)
 414                         do_deselect = 1;
 415
 416                 hlist_del_rcu(&gw_node->list);
 417                 gw_node_free_ref(gw_node);
 418         }
 419
 420         spin_unlock_bh(&bat_priv->gw_list_lock);
 421
 422         /* gw_deselect() needs to acquire the gw_list_lock */
 423         if (do_deselect)
 424                 gw_deselect(bat_priv);
 425
 426         if (curr_gw)
 427                 gw_node_free_ref(curr_gw);
 428 }
 429
 430 /**
 431  * fails if orig_node has no router
 432  */
 433 static int _write_buffer_text(struct bat_priv *bat_priv, struct seq_file *seq,
 434                               const struct gw_node *gw_node)
 435 {
 436         struct gw_node *curr_gw;
 437         struct neigh_node *router;
 438         int down, up, ret = -1;
 439
 440         gw_bandwidth_to_kbit(gw_node->orig_node->gw_flags, &down, &up);
 441
 442         router = orig_node_get_router(gw_node->orig_node);
 443         if (!router)
 444                 goto out;
 445
 446         curr_gw = gw_get_selected_gw_node(bat_priv);
 447
 448         ret = seq_printf(seq, "%s %pM (%3i) %pM [%10s]: %3i - %i%s/%i%s\n",
 449                          (curr_gw == gw_node ? "=>" : "  "),
 450                          gw_node->orig_node->orig,
 451                          router->tq_avg, router->addr,
 452                          router->if_incoming->net_dev->name,
 453                          gw_node->orig_node->gw_flags,
 454                          (down > 2048 ? down / 1024 : down),
 455                          (down > 2048 ? "MBit" : "KBit"),
 456                          (up > 2048 ? up / 1024 : up),
 457                          (up > 2048 ? "MBit" : "KBit"));
 458
 459         neigh_node_free_ref(router);
 460         if (curr_gw)
 461                 gw_node_free_ref(curr_gw);
 462 out:
 463         return ret;
 464 }
 465
 466 int gw_client_seq_print_text(struct seq_file *seq, void *offset)
 467 {
 468         struct net_device *net_dev = (struct net_device *)seq->private;
 469         struct bat_priv *bat_priv = netdev_priv(net_dev);
 470         struct hard_iface *primary_if;
 471         struct gw_node *gw_node;
 472         struct hlist_node *node;
 473         int gw_count = 0, ret = 0;
 474
 475         primary_if = primary_if_get_selected(bat_priv);
 476         if (!primary_if) {
 477                 ret = seq_printf(seq, "BATMAN mesh %s disabled - please "
 478                                  "specify interfaces to enable it\n",
 479                                  net_dev->name);
 480                 goto out;
 481         }
 482
 483         if (primary_if->if_status != IF_ACTIVE) {
 484                 ret = seq_printf(seq, "BATMAN mesh %s disabled - "
 485                                  "primary interface not active\n",
 486                                  net_dev->name);
 487                 goto out;
 488         }
 489
 490         seq_printf(seq, "      %-12s (%s/%i) %17s [%10s]: gw_class ... "
 491                    "[B.A.T.M.A.N. adv %s, MainIF/MAC: %s/%pM (%s)]\n",
 492                    "Gateway", "#", TQ_MAX_VALUE, "Nexthop",
 493                    "outgoingIF", SOURCE_VERSION, primary_if->net_dev->name,
 494                    primary_if->net_dev->dev_addr, net_dev->name);
 495
 496         rcu_read_lock();
 497         hlist_for_each_entry_rcu(gw_node, node, &bat_priv->gw_list, list) {
 498                 if (gw_node->deleted)
 499                         continue;
 500
 501                 /* fails if orig_node has no router */
 502                 if (_write_buffer_text(bat_priv, seq, gw_node) < 0)
 503                         continue;
 504
 505                 gw_count++;
 506         }
 507         rcu_read_unlock();
 508
 509         if (gw_count == 0)
 510                 seq_printf(seq, "No gateways in range ...\n");
 511
 512 out:
 513         if (primary_if)
 514                 hardif_free_ref(primary_if);
 515         return ret;
 516 }
 517
 518 static bool is_type_dhcprequest(struct sk_buff *skb, int header_len)
 519 {
 520         int ret = false;
 521         unsigned char *p;
 522         int pkt_len;
 523
 524         if (skb_linearize(skb) < 0)
 525                 goto out;
 526
 527         pkt_len = skb_headlen(skb);
 528
 529         if (pkt_len < header_len + DHCP_OPTIONS_OFFSET + 1)
 530                 goto out;
 531
 532         p = skb->data + header_len + DHCP_OPTIONS_OFFSET;
 533         pkt_len -= header_len + DHCP_OPTIONS_OFFSET + 1;
 534
 535         /* Access the dhcp option lists. Each entry is made up by:
 536          * - octet 1: option type
 537          * - octet 2: option data len (only if type != 255 and 0)
 538          * - octet 3: option data */
 539         while (*p != 255 && !ret) {
 540                 /* p now points to the first octet: option type */
 541                 if (*p == 53) {
 542                         /* type 53 is the message type option.
 543                          * Jump the len octet and go to the data octet */
 544                         if (pkt_len < 2)
 545                                 goto out;
 546                         p += 2;
 547
 548                         /* check if the message type is what we need */
 549                         if (*p == DHCP_REQUEST)
 550                                 ret = true;
 551                         break;
 552                 } else if (*p == 0) {
 553                         /* option type 0 (padding), just go forward */
 554                         if (pkt_len < 1)
 555                                 goto out;
 556                         pkt_len--;
 557                         p++;
 558                 } else {
 559                         /* This is any other option. So we get the length... */
 560                         if (pkt_len < 1)
 561                                 goto out;
 562                         pkt_len--;
 563                         p++;
 564
 565                         /* ...and then we jump over the data */
 566                         if (pkt_len < *p)
 567                                 goto out;
 568                         pkt_len -= *p;
 569                         p += (*p);
 570                 }
 571         }
 572 out:
 573         return ret;
 574 }
 575
 576 bool gw_is_dhcp_target(struct sk_buff *skb, unsigned int *header_len)
 577 {
 578         struct ethhdr *ethhdr;
 579         struct iphdr *iphdr;
 580         struct ipv6hdr *ipv6hdr;
 581         struct udphdr *udphdr;
 582
 583         /* check for ethernet header */
 584         if (!pskb_may_pull(skb, *header_len + ETH_HLEN))
 585                 return false;
 586         ethhdr = (struct ethhdr *)skb->data;
 587         *header_len += ETH_HLEN;
 588
 589         /* check for initial vlan header */
 590         if (ntohs(ethhdr->h_proto) == ETH_P_8021Q) {
 591                 if (!pskb_may_pull(skb, *header_len + VLAN_HLEN))
 592                         return false;
 593                 ethhdr = (struct ethhdr *)(skb->data + VLAN_HLEN);
 594                 *header_len += VLAN_HLEN;
 595         }
 596
 597         /* check for ip header */
 598         switch (ntohs(ethhdr->h_proto)) {
 599         case ETH_P_IP:
 600                 if (!pskb_may_pull(skb, *header_len + sizeof(*iphdr)))
 601                         return false;
 602                 iphdr = (struct iphdr *)(skb->data + *header_len);
 603                 *header_len += iphdr->ihl * 4;
 604
 605                 /* check for udp header */
 606                 if (iphdr->protocol != IPPROTO_UDP)
 607                         return false;
 608
 609                 break;
 610         case ETH_P_IPV6:
 611                 if (!pskb_may_pull(skb, *header_len + sizeof(*ipv6hdr)))
 612                         return false;
 613                 ipv6hdr = (struct ipv6hdr *)(skb->data + *header_len);
 614                 *header_len += sizeof(*ipv6hdr);
 615
 616                 /* check for udp header */
 617                 if (ipv6hdr->nexthdr != IPPROTO_UDP)
 618                         return false;
 619
 620                 break;
 621         default:
 622                 return false;
 623         }
 624
 625         if (!pskb_may_pull(skb, *header_len + sizeof(*udphdr)))
 626                 return false;
 627         udphdr = (struct udphdr *)(skb->data + *header_len);
 628         *header_len += sizeof(*udphdr);
 629
 630         /* check for bootp port */
 631         if ((ntohs(ethhdr->h_proto) == ETH_P_IP) &&
 632              (ntohs(udphdr->dest) != 67))
 633                 return false;
 634
 635         if ((ntohs(ethhdr->h_proto) == ETH_P_IPV6) &&
 636             (ntohs(udphdr->dest) != 547))
 637                 return false;
 638
 639         return true;
 640 }
 641
 642 bool gw_out_of_range(struct bat_priv *bat_priv,
 643                      struct sk_buff *skb, struct ethhdr *ethhdr)
 644 {
 645         struct neigh_node *neigh_curr = NULL, *neigh_old = NULL;
 646         struct orig_node *orig_dst_node = NULL;
 647         struct gw_node *curr_gw = NULL;
 648         bool ret, out_of_range = false;
 649         unsigned int header_len = 0;
 650         uint8_t curr_tq_avg;
 651
 652         ret = gw_is_dhcp_target(skb, &header_len);
 653         if (!ret)
 654                 goto out;
 655
 656         orig_dst_node = transtable_search(bat_priv, ethhdr->h_source,
 657                                           ethhdr->h_dest);
 658         if (!orig_dst_node)
 659                 goto out;
 660
 661         if (!orig_dst_node->gw_flags)
 662                 goto out;
 663
 664         ret = is_type_dhcprequest(skb, header_len);
 665         if (!ret)
 666                 goto out;
 667
 668         switch (atomic_read(&bat_priv->gw_mode)) {
 669         case GW_MODE_SERVER:
 670                 /* If we are a GW then we are our best GW. We can artificially
 671                  * set the tq towards ourself as the maximum value */
 672                 curr_tq_avg = TQ_MAX_VALUE;
 673                 break;
 674         case GW_MODE_CLIENT:
 675                 curr_gw = gw_get_selected_gw_node(bat_priv);
 676                 if (!curr_gw)
 677                         goto out;
 678
 679                 /* packet is going to our gateway */
 680                 if (curr_gw->orig_node == orig_dst_node)
 681                         goto out;
 682
 683                 /* If the dhcp packet has been sent to a different gw,
 684                  * we have to evaluate whether the old gw is still
 685                  * reliable enough */
 686                 neigh_curr = find_router(bat_priv, curr_gw->orig_node, NULL);
 687                 if (!neigh_curr)
 688                         goto out;
 689
 690                 curr_tq_avg = neigh_curr->tq_avg;
 691                 break;
 692         case GW_MODE_OFF:
 693         default:
 694                 goto out;
 695         }
 696
 697         neigh_old = find_router(bat_priv, orig_dst_node, NULL);
 698         if (!neigh_old)
 699                 goto out;
 700
 701         if (curr_tq_avg - neigh_old->tq_avg > GW_THRESHOLD)
 702                 out_of_range = true;
 703
 704 out:
 705         if (orig_dst_node)
 706                 orig_node_free_ref(orig_dst_node);
 707         if (curr_gw)
 708                 gw_node_free_ref(curr_gw);
 709         if (neigh_old)
 710                 neigh_node_free_ref(neigh_old);
 711         if (neigh_curr)
 712                 neigh_node_free_ref(neigh_curr);
 713         return out_of_range;
 714 }