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 "bat_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 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 gw_node *batadv_gw_get_selected_gw_node(struct bat_priv *bat_priv)
  46 {
  47         struct gw_node *gw_node;
  48
  49         rcu_read_lock();
  50         gw_node = rcu_dereference(bat_priv->curr_gw);
  51         if (!gw_node)
  52                 goto out;
  53
  54         if (!atomic_inc_not_zero(&gw_node->refcount))
  55                 gw_node = NULL;
  56
  57 out:
  58         rcu_read_unlock();
  59         return gw_node;
  60 }
  61
  62 struct orig_node *batadv_gw_get_selected_orig(struct bat_priv *bat_priv)
  63 {
  64         struct gw_node *gw_node;
  65         struct orig_node *orig_node = NULL;
  66
  67         gw_node = batadv_gw_get_selected_gw_node(bat_priv);
  68         if (!gw_node)
  69                 goto out;
  70
  71         rcu_read_lock();
  72         orig_node = gw_node->orig_node;
  73         if (!orig_node)
  74                 goto unlock;
  75
  76         if (!atomic_inc_not_zero(&orig_node->refcount))
  77                 orig_node = NULL;
  78
  79 unlock:
  80         rcu_read_unlock();
  81 out:
  82         if (gw_node)
  83                 batadv_gw_node_free_ref(gw_node);
  84         return orig_node;
  85 }
  86
  87 static void batadv_gw_select(struct bat_priv *bat_priv,
  88                              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                 batadv_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 *batadv_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         struct orig_node *orig_node;
 120
 121         rcu_read_lock();
 122         hlist_for_each_entry_rcu(gw_node, node, &bat_priv->gw_list, list) {
 123                 if (gw_node->deleted)
 124                         continue;
 125
 126                 orig_node = gw_node->orig_node;
 127                 router = batadv_orig_node_get_router(orig_node);
 128                 if (!router)
 129                         continue;
 130
 131                 if (!atomic_inc_not_zero(&gw_node->refcount))
 132                         goto next;
 133
 134                 switch (atomic_read(&bat_priv->gw_sel_class)) {
 135                 case 1: /* fast connection */
 136                         batadv_gw_bandwidth_to_kbit(orig_node->gw_flags,
 137                                                     &down, &up);
 138
 139                         tmp_gw_factor = (router->tq_avg * router->tq_avg *
 140                                          down * 100 * 100) /
 141                                          (BATADV_TQ_LOCAL_WINDOW_SIZE *
 142                                           BATADV_TQ_LOCAL_WINDOW_SIZE * 64);
 143
 144                         if ((tmp_gw_factor > max_gw_factor) ||
 145                             ((tmp_gw_factor == max_gw_factor) &&
 146                              (router->tq_avg > max_tq))) {
 147                                 if (curr_gw)
 148                                         batadv_gw_node_free_ref(curr_gw);
 149                                 curr_gw = gw_node;
 150                                 atomic_inc(&curr_gw->refcount);
 151                         }
 152                         break;
 153
 154                 default: /* 2:  stable connection (use best statistic)
 155                           * 3:  fast-switch (use best statistic but change as
 156                           *     soon as a better gateway appears)
 157                           * XX: late-switch (use best statistic but change as
 158                           *     soon as a better gateway appears which has
 159                           *     $routing_class more tq points)
 160                           */
 161                         if (router->tq_avg > max_tq) {
 162                                 if (curr_gw)
 163                                         batadv_gw_node_free_ref(curr_gw);
 164                                 curr_gw = gw_node;
 165                                 atomic_inc(&curr_gw->refcount);
 166                         }
 167                         break;
 168                 }
 169
 170                 if (router->tq_avg > max_tq)
 171                         max_tq = router->tq_avg;
 172
 173                 if (tmp_gw_factor > max_gw_factor)
 174                         max_gw_factor = tmp_gw_factor;
 175
 176                 batadv_gw_node_free_ref(gw_node);
 177
 178 next:
 179                 batadv_neigh_node_free_ref(router);
 180         }
 181         rcu_read_unlock();
 182
 183         return curr_gw;
 184 }
 185
 186 void batadv_gw_election(struct bat_priv *bat_priv)
 187 {
 188         struct gw_node *curr_gw = NULL, *next_gw = NULL;
 189         struct neigh_node *router = NULL;
 190         char gw_addr[18] = { '\0' };
 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) != BATADV_GW_MODE_CLIENT)
 198                 goto out;
 199
 200         if (!batadv_atomic_dec_not_zero(&bat_priv->gw_reselect))
 201                 goto out;
 202
 203         curr_gw = batadv_gw_get_selected_gw_node(bat_priv);
 204
 205         next_gw = batadv_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 = batadv_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                 batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
 222                            "Removing selected gateway - no gateway in range\n");
 223                 batadv_throw_uevent(bat_priv, BATADV_UEV_GW, BATADV_UEV_DEL,
 224                                     NULL);
 225         } else if ((!curr_gw) && (next_gw)) {
 226                 batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
 227                            "Adding route to gateway %pM (gw_flags: %i, tq: %i)\n",
 228                            next_gw->orig_node->orig,
 229                            next_gw->orig_node->gw_flags, router->tq_avg);
 230                 batadv_throw_uevent(bat_priv, BATADV_UEV_GW, BATADV_UEV_ADD,
 231                                     gw_addr);
 232         } else {
 233                 batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
 234                            "Changing route to gateway %pM (gw_flags: %i, tq: %i)\n",
 235                            next_gw->orig_node->orig,
 236                            next_gw->orig_node->gw_flags, router->tq_avg);
 237                 batadv_throw_uevent(bat_priv, BATADV_UEV_GW, BATADV_UEV_CHANGE,
 238                                     gw_addr);
 239         }
 240
 241         batadv_gw_select(bat_priv, next_gw);
 242
 243 out:
 244         if (curr_gw)
 245                 batadv_gw_node_free_ref(curr_gw);
 246         if (next_gw)
 247                 batadv_gw_node_free_ref(next_gw);
 248         if (router)
 249                 batadv_neigh_node_free_ref(router);
 250 }
 251
 252 void batadv_gw_check_election(struct bat_priv *bat_priv,
 253                               struct orig_node *orig_node)
 254 {
 255         struct orig_node *curr_gw_orig;
 256         struct neigh_node *router_gw = NULL, *router_orig = NULL;
 257         uint8_t gw_tq_avg, orig_tq_avg;
 258
 259         curr_gw_orig = batadv_gw_get_selected_orig(bat_priv);
 260         if (!curr_gw_orig)
 261                 goto deselect;
 262
 263         router_gw = batadv_orig_node_get_router(curr_gw_orig);
 264         if (!router_gw)
 265                 goto deselect;
 266
 267         /* this node already is the gateway */
 268         if (curr_gw_orig == orig_node)
 269                 goto out;
 270
 271         router_orig = batadv_orig_node_get_router(orig_node);
 272         if (!router_orig)
 273                 goto out;
 274
 275         gw_tq_avg = router_gw->tq_avg;
 276         orig_tq_avg = router_orig->tq_avg;
 277
 278         /* the TQ value has to be better */
 279         if (orig_tq_avg < gw_tq_avg)
 280                 goto out;
 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         batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
 290                    "Restarting gateway selection: better gateway found (tq curr: %i, tq new: %i)\n",
 291                    gw_tq_avg, orig_tq_avg);
 292
 293 deselect:
 294         batadv_gw_deselect(bat_priv);
 295 out:
 296         if (curr_gw_orig)
 297                 batadv_orig_node_free_ref(curr_gw_orig);
 298         if (router_gw)
 299                 batadv_neigh_node_free_ref(router_gw);
 300         if (router_orig)
 301                 batadv_neigh_node_free_ref(router_orig);
 302
 303         return;
 304 }
 305
 306 static void batadv_gw_node_add(struct bat_priv *bat_priv,
 307                                struct orig_node *orig_node,
 308                                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         batadv_gw_bandwidth_to_kbit(new_gwflags, &down, &up);
 326         batadv_dbg(BATADV_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 batadv_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         /* Note: We don't need a NULL check here, since curr_gw never gets
 342          * dereferenced. If curr_gw is NULL we also should not exit as we may
 343          * have this gateway in our list (duplication check!) even though we
 344          * have no currently selected gateway.
 345          */
 346         curr_gw = batadv_gw_get_selected_gw_node(bat_priv);
 347
 348         rcu_read_lock();
 349         hlist_for_each_entry_rcu(gw_node, node, &bat_priv->gw_list, list) {
 350                 if (gw_node->orig_node != orig_node)
 351                         continue;
 352
 353                 batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
 354                            "Gateway class of originator %pM changed from %i to %i\n",
 355                            orig_node->orig, gw_node->orig_node->gw_flags,
 356                            new_gwflags);
 357
 358                 gw_node->deleted = 0;
 359
 360                 if (new_gwflags == BATADV_NO_FLAGS) {
 361                         gw_node->deleted = jiffies;
 362                         batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
 363                                    "Gateway %pM removed from gateway list\n",
 364                                    orig_node->orig);
 365
 366                         if (gw_node == curr_gw)
 367                                 goto deselect;
 368                 }
 369
 370                 goto unlock;
 371         }
 372
 373         if (new_gwflags == BATADV_NO_FLAGS)
 374                 goto unlock;
 375
 376         batadv_gw_node_add(bat_priv, orig_node, new_gwflags);
 377         goto unlock;
 378
 379 deselect:
 380         batadv_gw_deselect(bat_priv);
 381 unlock:
 382         rcu_read_unlock();
 383
 384         if (curr_gw)
 385                 batadv_gw_node_free_ref(curr_gw);
 386 }
 387
 388 void batadv_gw_node_delete(struct bat_priv *bat_priv,
 389                            struct orig_node *orig_node)
 390 {
 391         batadv_gw_node_update(bat_priv, orig_node, 0);
 392 }
 393
 394 void batadv_gw_node_purge(struct bat_priv *bat_priv)
 395 {
 396         struct gw_node *gw_node, *curr_gw;
 397         struct hlist_node *node, *node_tmp;
 398         unsigned long timeout = msecs_to_jiffies(2 * BATADV_PURGE_TIMEOUT);
 399         int do_deselect = 0;
 400
 401         curr_gw = batadv_gw_get_selected_gw_node(bat_priv);
 402
 403         spin_lock_bh(&bat_priv->gw_list_lock);
 404
 405         hlist_for_each_entry_safe(gw_node, node, node_tmp,
 406                                   &bat_priv->gw_list, list) {
 407                 if (((!gw_node->deleted) ||
 408                      (time_before(jiffies, gw_node->deleted + timeout))) &&
 409                     atomic_read(&bat_priv->mesh_state) == BATADV_MESH_ACTIVE)
 410                         continue;
 411
 412                 if (curr_gw == gw_node)
 413                         do_deselect = 1;
 414
 415                 hlist_del_rcu(&gw_node->list);
 416                 batadv_gw_node_free_ref(gw_node);
 417         }
 418
 419         spin_unlock_bh(&bat_priv->gw_list_lock);
 420
 421         /* gw_deselect() needs to acquire the gw_list_lock */
 422         if (do_deselect)
 423                 batadv_gw_deselect(bat_priv);
 424
 425         if (curr_gw)
 426                 batadv_gw_node_free_ref(curr_gw);
 427 }
 428
 429 /* fails if orig_node has no router */
 430 static int batadv_write_buffer_text(struct bat_priv *bat_priv,
 431                                      struct seq_file *seq,
 432                                      const struct gw_node *gw_node)
 433 {
 434         struct gw_node *curr_gw;
 435         struct neigh_node *router;
 436         int down, up, ret = -1;
 437
 438         batadv_gw_bandwidth_to_kbit(gw_node->orig_node->gw_flags, &down, &up);
 439
 440         router = batadv_orig_node_get_router(gw_node->orig_node);
 441         if (!router)
 442                 goto out;
 443
 444         curr_gw = batadv_gw_get_selected_gw_node(bat_priv);
 445
 446         ret = seq_printf(seq, "%s %pM (%3i) %pM [%10s]: %3i - %i%s/%i%s\n",
 447                          (curr_gw == gw_node ? "=>" : "  "),
 448                          gw_node->orig_node->orig,
 449                          router->tq_avg, router->addr,
 450                          router->if_incoming->net_dev->name,
 451                          gw_node->orig_node->gw_flags,
 452                          (down > 2048 ? down / 1024 : down),
 453                          (down > 2048 ? "MBit" : "KBit"),
 454                          (up > 2048 ? up / 1024 : up),
 455                          (up > 2048 ? "MBit" : "KBit"));
 456
 457         batadv_neigh_node_free_ref(router);
 458         if (curr_gw)
 459                 batadv_gw_node_free_ref(curr_gw);
 460 out:
 461         return ret;
 462 }
 463
 464 int batadv_gw_client_seq_print_text(struct seq_file *seq, void *offset)
 465 {
 466         struct net_device *net_dev = (struct net_device *)seq->private;
 467         struct bat_priv *bat_priv = netdev_priv(net_dev);
 468         struct hard_iface *primary_if;
 469         struct gw_node *gw_node;
 470         struct hlist_node *node;
 471         int gw_count = 0, ret = 0;
 472
 473         primary_if = batadv_primary_if_get_selected(bat_priv);
 474         if (!primary_if) {
 475                 ret = seq_printf(seq,
 476                                  "BATMAN mesh %s disabled - please specify interfaces to enable it\n",
 477                                  net_dev->name);
 478                 goto out;
 479         }
 480
 481         if (primary_if->if_status != BATADV_IF_ACTIVE) {
 482                 ret = seq_printf(seq,
 483                                  "BATMAN mesh %s disabled - primary interface not active\n",
 484                                  net_dev->name);
 485                 goto out;
 486         }
 487
 488         seq_printf(seq,
 489                    "      %-12s (%s/%i) %17s [%10s]: gw_class ... [B.A.T.M.A.N. adv %s, MainIF/MAC: %s/%pM (%s)]\n",
 490                    "Gateway", "#", BATADV_TQ_MAX_VALUE, "Nexthop", "outgoingIF",
 491                    BATADV_SOURCE_VERSION, primary_if->net_dev->name,
 492                    primary_if->net_dev->dev_addr, net_dev->name);
 493
 494         rcu_read_lock();
 495         hlist_for_each_entry_rcu(gw_node, node, &bat_priv->gw_list, list) {
 496                 if (gw_node->deleted)
 497                         continue;
 498
 499                 /* fails if orig_node has no router */
 500                 if (batadv_write_buffer_text(bat_priv, seq, gw_node) < 0)
 501                         continue;
 502
 503                 gw_count++;
 504         }
 505         rcu_read_unlock();
 506
 507         if (gw_count == 0)
 508                 seq_printf(seq, "No gateways in range ...\n");
 509
 510 out:
 511         if (primary_if)
 512                 batadv_hardif_free_ref(primary_if);
 513         return ret;
 514 }
 515
 516 static bool batadv_is_type_dhcprequest(struct sk_buff *skb, int header_len)
 517 {
 518         int ret = false;
 519         unsigned char *p;
 520         int pkt_len;
 521
 522         if (skb_linearize(skb) < 0)
 523                 goto out;
 524
 525         pkt_len = skb_headlen(skb);
 526
 527         if (pkt_len < header_len + BATADV_DHCP_OPTIONS_OFFSET + 1)
 528                 goto out;
 529
 530         p = skb->data + header_len + BATADV_DHCP_OPTIONS_OFFSET;
 531         pkt_len -= header_len + BATADV_DHCP_OPTIONS_OFFSET + 1;
 532
 533         /* Access the dhcp option lists. Each entry is made up by:
 534          * - octet 1: option type
 535          * - octet 2: option data len (only if type != 255 and 0)
 536          * - octet 3: option data
 537          */
 538         while (*p != 255 && !ret) {
 539                 /* p now points to the first octet: option type */
 540                 if (*p == 53) {
 541                         /* type 53 is the message type option.
 542                          * Jump the len octet and go to the data octet
 543                          */
 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 == BATADV_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 < 1 + (*p))
 567                                 goto out;
 568                         pkt_len -= 1 + (*p);
 569                         p += 1 + (*p);
 570                 }
 571         }
 572 out:
 573         return ret;
 574 }
 575
 576 bool batadv_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 batadv_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 = batadv_gw_is_dhcp_target(skb, &header_len);
 653         if (!ret)
 654                 goto out;
 655
 656         orig_dst_node = batadv_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 = batadv_is_type_dhcprequest(skb, header_len);
 665         if (!ret)
 666                 goto out;
 667
 668         switch (atomic_read(&bat_priv->gw_mode)) {
 669         case BATADV_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                  */
 673                 curr_tq_avg = BATADV_TQ_MAX_VALUE;
 674                 break;
 675         case BATADV_GW_MODE_CLIENT:
 676                 curr_gw = batadv_gw_get_selected_gw_node(bat_priv);
 677                 if (!curr_gw)
 678                         goto out;
 679
 680                 /* packet is going to our gateway */
 681                 if (curr_gw->orig_node == orig_dst_node)
 682                         goto out;
 683
 684                 /* If the dhcp packet has been sent to a different gw,
 685                  * we have to evaluate whether the old gw is still
 686                  * reliable enough
 687                  */
 688                 neigh_curr = batadv_find_router(bat_priv, curr_gw->orig_node,
 689                                                 NULL);
 690                 if (!neigh_curr)
 691                         goto out;
 692
 693                 curr_tq_avg = neigh_curr->tq_avg;
 694                 break;
 695         case BATADV_GW_MODE_OFF:
 696         default:
 697                 goto out;
 698         }
 699
 700         neigh_old = batadv_find_router(bat_priv, orig_dst_node, NULL);
 701         if (!neigh_old)
 702                 goto out;
 703
 704         if (curr_tq_avg - neigh_old->tq_avg > BATADV_GW_THRESHOLD)
 705                 out_of_range = true;
 706
 707 out:
 708         if (orig_dst_node)
 709                 batadv_orig_node_free_ref(orig_dst_node);
 710         if (curr_gw)
 711                 batadv_gw_node_free_ref(curr_gw);
 712         if (neigh_old)
 713                 batadv_neigh_node_free_ref(neigh_old);
 714         if (neigh_curr)
 715                 batadv_neigh_node_free_ref(neigh_curr);
 716         return out_of_range;
 717 }