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