net/batman-adv/gateway_client.c

   1 /* Copyright (C) 2009-2013 B.A.T.M.A.N. contributors:
   2  *
   3  * Marek Lindner
   4  *
   5  * This program is free software; you can redistribute it and/or
   6  * modify it under the terms of version 2 of the GNU General Public
   7  * License as published by the Free Software Foundation.
   8  *
   9  * This program is distributed in the hope that it will be useful, but
  10  * WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  12  * General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License
  15  * along with this program; if not, write to the Free Software
  16  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
  17  * 02110-1301, USA
  18  */
  19
  20 #include "main.h"
  21 #include "sysfs.h"
  22 #include "gateway_client.h"
  23 #include "gateway_common.h"
  24 #include "hard-interface.h"
  25 #include "originator.h"
  26 #include "translation-table.h"
  27 #include "routing.h"
  28 #include <linux/ip.h>
  29 #include <linux/ipv6.h>
  30 #include <linux/udp.h>
  31 #include <linux/if_vlan.h>
  32
  33 /* This is the offset of the options field in a dhcp packet starting at
  34  * the beginning of the dhcp header
  35  */
  36 #define BATADV_DHCP_OPTIONS_OFFSET 240
  37 #define BATADV_DHCP_REQUEST 3
  38
  39 static void batadv_gw_node_free_ref(struct batadv_gw_node *gw_node)
  40 {
  41         if (atomic_dec_and_test(&gw_node->refcount))
  42                 kfree_rcu(gw_node, rcu);
  43 }
  44
  45 static struct batadv_gw_node *
  46 batadv_gw_get_selected_gw_node(struct batadv_priv *bat_priv)
  47 {
  48         struct batadv_gw_node *gw_node;
  49
  50         rcu_read_lock();
  51         gw_node = rcu_dereference(bat_priv->gw.curr_gw);
  52         if (!gw_node)
  53                 goto out;
  54
  55         if (!atomic_inc_not_zero(&gw_node->refcount))
  56                 gw_node = NULL;
  57
  58 out:
  59         rcu_read_unlock();
  60         return gw_node;
  61 }
  62
  63 struct batadv_orig_node *
  64 batadv_gw_get_selected_orig(struct batadv_priv *bat_priv)
  65 {
  66         struct batadv_gw_node *gw_node;
  67         struct batadv_orig_node *orig_node = NULL;
  68
  69         gw_node = batadv_gw_get_selected_gw_node(bat_priv);
  70         if (!gw_node)
  71                 goto out;
  72
  73         rcu_read_lock();
  74         orig_node = gw_node->orig_node;
  75         if (!orig_node)
  76                 goto unlock;
  77
  78         if (!atomic_inc_not_zero(&orig_node->refcount))
  79                 orig_node = NULL;
  80
  81 unlock:
  82         rcu_read_unlock();
  83 out:
  84         if (gw_node)
  85                 batadv_gw_node_free_ref(gw_node);
  86         return orig_node;
  87 }
  88
  89 static void batadv_gw_select(struct batadv_priv *bat_priv,
  90                              struct batadv_gw_node *new_gw_node)
  91 {
  92         struct batadv_gw_node *curr_gw_node;
  93
  94         spin_lock_bh(&bat_priv->gw.list_lock);
  95
  96         if (new_gw_node && !atomic_inc_not_zero(&new_gw_node->refcount))
  97                 new_gw_node = NULL;
  98
  99         curr_gw_node = rcu_dereference_protected(bat_priv->gw.curr_gw, 1);
 100         rcu_assign_pointer(bat_priv->gw.curr_gw, new_gw_node);
 101
 102         if (curr_gw_node)
 103                 batadv_gw_node_free_ref(curr_gw_node);
 104
 105         spin_unlock_bh(&bat_priv->gw.list_lock);
 106 }
 107
 108 void batadv_gw_deselect(struct batadv_priv *bat_priv)
 109 {
 110         atomic_set(&bat_priv->gw.reselect, 1);
 111 }
 112
 113 static struct batadv_gw_node *
 114 batadv_gw_get_best_gw_node(struct batadv_priv *bat_priv)
 115 {
 116         struct batadv_neigh_node *router;
 117         struct batadv_gw_node *gw_node, *curr_gw = NULL;
 118         uint32_t max_gw_factor = 0, tmp_gw_factor = 0;
 119         uint32_t gw_divisor;
 120         uint8_t max_tq = 0;
 121         int down, up;
 122         uint8_t tq_avg;
 123         struct batadv_orig_node *orig_node;
 124
 125         gw_divisor = BATADV_TQ_LOCAL_WINDOW_SIZE * BATADV_TQ_LOCAL_WINDOW_SIZE;
 126         gw_divisor *= 64;
 127
 128         rcu_read_lock();
 129         hlist_for_each_entry_rcu(gw_node, &bat_priv->gw.list, list) {
 130                 if (gw_node->deleted)
 131                         continue;
 132
 133                 orig_node = gw_node->orig_node;
 134                 router = batadv_orig_node_get_router(orig_node);
 135                 if (!router)
 136                         continue;
 137
 138                 if (!atomic_inc_not_zero(&gw_node->refcount))
 139                         goto next;
 140
 141                 tq_avg = router->tq_avg;
 142
 143                 switch (atomic_read(&bat_priv->gw_sel_class)) {
 144                 case 1: /* fast connection */
 145                         batadv_gw_bandwidth_to_kbit(orig_node->gw_flags,
 146                                                     &down, &up);
 147
 148                         tmp_gw_factor = tq_avg * tq_avg * down * 100 * 100;
 149                         tmp_gw_factor /= gw_divisor;
 150
 151                         if ((tmp_gw_factor > max_gw_factor) ||
 152                             ((tmp_gw_factor == max_gw_factor) &&
 153                              (tq_avg > max_tq))) {
 154                                 if (curr_gw)
 155                                         batadv_gw_node_free_ref(curr_gw);
 156                                 curr_gw = gw_node;
 157                                 atomic_inc(&curr_gw->refcount);
 158                         }
 159                         break;
 160
 161                 default: /* 2:  stable connection (use best statistic)
 162                           * 3:  fast-switch (use best statistic but change as
 163                           *     soon as a better gateway appears)
 164                           * XX: late-switch (use best statistic but change as
 165                           *     soon as a better gateway appears which has
 166                           *     $routing_class more tq points)
 167                           */
 168                         if (tq_avg > max_tq) {
 169                                 if (curr_gw)
 170                                         batadv_gw_node_free_ref(curr_gw);
 171                                 curr_gw = gw_node;
 172                                 atomic_inc(&curr_gw->refcount);
 173                         }
 174                         break;
 175                 }
 176
 177                 if (tq_avg > max_tq)
 178                         max_tq = tq_avg;
 179
 180                 if (tmp_gw_factor > max_gw_factor)
 181                         max_gw_factor = tmp_gw_factor;
 182
 183                 batadv_gw_node_free_ref(gw_node);
 184
 185 next:
 186                 batadv_neigh_node_free_ref(router);
 187         }
 188         rcu_read_unlock();
 189
 190         return curr_gw;
 191 }
 192
 193 void batadv_gw_election(struct batadv_priv *bat_priv)
 194 {
 195         struct batadv_gw_node *curr_gw = NULL, *next_gw = NULL;
 196         struct batadv_neigh_node *router = NULL;
 197         char gw_addr[18] = { '\0' };
 198
 199         /* The batman daemon checks here if we already passed a full originator
 200          * cycle in order to make sure we don't choose the first gateway we
 201          * hear about. This check is based on the daemon's uptime which we
 202          * don't have.
 203          */
 204         if (atomic_read(&bat_priv->gw_mode) != BATADV_GW_MODE_CLIENT)
 205                 goto out;
 206
 207         curr_gw = batadv_gw_get_selected_gw_node(bat_priv);
 208
 209         if (!batadv_atomic_dec_not_zero(&bat_priv->gw.reselect) && curr_gw)
 210                 goto out;
 211
 212         next_gw = batadv_gw_get_best_gw_node(bat_priv);
 213
 214         if (curr_gw == next_gw)
 215                 goto out;
 216
 217         if (next_gw) {
 218                 sprintf(gw_addr, "%pM", next_gw->orig_node->orig);
 219
 220                 router = batadv_orig_node_get_router(next_gw->orig_node);
 221                 if (!router) {
 222                         batadv_gw_deselect(bat_priv);
 223                         goto out;
 224                 }
 225         }
 226
 227         if ((curr_gw) && (!next_gw)) {
 228                 batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
 229                            "Removing selected gateway - no gateway in range\n");
 230                 batadv_throw_uevent(bat_priv, BATADV_UEV_GW, BATADV_UEV_DEL,
 231                                     NULL);
 232         } else if ((!curr_gw) && (next_gw)) {
 233                 batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
 234                            "Adding 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_ADD,
 238                                     gw_addr);
 239         } else {
 240                 batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
 241                            "Changing route to gateway %pM (gw_flags: %i, tq: %i)\n",
 242                            next_gw->orig_node->orig,
 243                            next_gw->orig_node->gw_flags, router->tq_avg);
 244                 batadv_throw_uevent(bat_priv, BATADV_UEV_GW, BATADV_UEV_CHANGE,
 245                                     gw_addr);
 246         }
 247
 248         batadv_gw_select(bat_priv, next_gw);
 249
 250 out:
 251         if (curr_gw)
 252                 batadv_gw_node_free_ref(curr_gw);
 253         if (next_gw)
 254                 batadv_gw_node_free_ref(next_gw);
 255         if (router)
 256                 batadv_neigh_node_free_ref(router);
 257 }
 258
 259 void batadv_gw_check_election(struct batadv_priv *bat_priv,
 260                               struct batadv_orig_node *orig_node)
 261 {
 262         struct batadv_orig_node *curr_gw_orig;
 263         struct batadv_neigh_node *router_gw = NULL, *router_orig = NULL;
 264         uint8_t gw_tq_avg, orig_tq_avg;
 265
 266         curr_gw_orig = batadv_gw_get_selected_orig(bat_priv);
 267         if (!curr_gw_orig)
 268                 goto deselect;
 269
 270         router_gw = batadv_orig_node_get_router(curr_gw_orig);
 271         if (!router_gw)
 272                 goto deselect;
 273
 274         /* this node already is the gateway */
 275         if (curr_gw_orig == orig_node)
 276                 goto out;
 277
 278         router_orig = batadv_orig_node_get_router(orig_node);
 279         if (!router_orig)
 280                 goto out;
 281
 282         gw_tq_avg = router_gw->tq_avg;
 283         orig_tq_avg = router_orig->tq_avg;
 284
 285         /* the TQ value has to be better */
 286         if (orig_tq_avg < gw_tq_avg)
 287                 goto out;
 288
 289         /* if the routing class is greater than 3 the value tells us how much
 290          * greater the TQ value of the new gateway must be
 291          */
 292         if ((atomic_read(&bat_priv->gw_sel_class) > 3) &&
 293             (orig_tq_avg - gw_tq_avg < atomic_read(&bat_priv->gw_sel_class)))
 294                 goto out;
 295
 296         batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
 297                    "Restarting gateway selection: better gateway found (tq curr: %i, tq new: %i)\n",
 298                    gw_tq_avg, orig_tq_avg);
 299
 300 deselect:
 301         batadv_gw_deselect(bat_priv);
 302 out:
 303         if (curr_gw_orig)
 304                 batadv_orig_node_free_ref(curr_gw_orig);
 305         if (router_gw)
 306                 batadv_neigh_node_free_ref(router_gw);
 307         if (router_orig)
 308                 batadv_neigh_node_free_ref(router_orig);
 309
 310         return;
 311 }
 312
 313 static void batadv_gw_node_add(struct batadv_priv *bat_priv,
 314                                struct batadv_orig_node *orig_node,
 315                                uint8_t new_gwflags)
 316 {
 317         struct batadv_gw_node *gw_node;
 318         int down, up;
 319
 320         gw_node = kzalloc(sizeof(*gw_node), GFP_ATOMIC);
 321         if (!gw_node)
 322                 return;
 323
 324         INIT_HLIST_NODE(&gw_node->list);
 325         gw_node->orig_node = orig_node;
 326         atomic_set(&gw_node->refcount, 1);
 327
 328         spin_lock_bh(&bat_priv->gw.list_lock);
 329         hlist_add_head_rcu(&gw_node->list, &bat_priv->gw.list);
 330         spin_unlock_bh(&bat_priv->gw.list_lock);
 331
 332         batadv_gw_bandwidth_to_kbit(new_gwflags, &down, &up);
 333         batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
 334                    "Found new gateway %pM -> gw_class: %i - %i%s/%i%s\n",
 335                    orig_node->orig, new_gwflags,
 336                    (down > 2048 ? down / 1024 : down),
 337                    (down > 2048 ? "MBit" : "KBit"),
 338                    (up > 2048 ? up / 1024 : up),
 339                    (up > 2048 ? "MBit" : "KBit"));
 340 }
 341
 342 void batadv_gw_node_update(struct batadv_priv *bat_priv,
 343                            struct batadv_orig_node *orig_node,
 344                            uint8_t new_gwflags)
 345 {
 346         struct batadv_gw_node *gw_node, *curr_gw;
 347
 348         /* Note: We don't need a NULL check here, since curr_gw never gets
 349          * dereferenced. If curr_gw is NULL we also should not exit as we may
 350          * have this gateway in our list (duplication check!) even though we
 351          * have no currently selected gateway.
 352          */
 353         curr_gw = batadv_gw_get_selected_gw_node(bat_priv);
 354
 355         rcu_read_lock();
 356         hlist_for_each_entry_rcu(gw_node, &bat_priv->gw.list, list) {
 357                 if (gw_node->orig_node != orig_node)
 358                         continue;
 359
 360                 batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
 361                            "Gateway class of originator %pM changed from %i to %i\n",
 362                            orig_node->orig, gw_node->orig_node->gw_flags,
 363                            new_gwflags);
 364
 365                 gw_node->deleted = 0;
 366
 367                 if (new_gwflags == BATADV_NO_FLAGS) {
 368                         gw_node->deleted = jiffies;
 369                         batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
 370                                    "Gateway %pM removed from gateway list\n",
 371                                    orig_node->orig);
 372
 373                         if (gw_node == curr_gw)
 374                                 goto deselect;
 375                 }
 376
 377                 goto unlock;
 378         }
 379
 380         if (new_gwflags == BATADV_NO_FLAGS)
 381                 goto unlock;
 382
 383         batadv_gw_node_add(bat_priv, orig_node, new_gwflags);
 384         goto unlock;
 385
 386 deselect:
 387         batadv_gw_deselect(bat_priv);
 388 unlock:
 389         rcu_read_unlock();
 390
 391         if (curr_gw)
 392                 batadv_gw_node_free_ref(curr_gw);
 393 }
 394
 395 void batadv_gw_node_delete(struct batadv_priv *bat_priv,
 396                            struct batadv_orig_node *orig_node)
 397 {
 398         batadv_gw_node_update(bat_priv, orig_node, 0);
 399 }
 400
 401 void batadv_gw_node_purge(struct batadv_priv *bat_priv)
 402 {
 403         struct batadv_gw_node *gw_node, *curr_gw;
 404         struct hlist_node *node_tmp;
 405         unsigned long timeout = msecs_to_jiffies(2 * BATADV_PURGE_TIMEOUT);
 406         int do_deselect = 0;
 407
 408         curr_gw = batadv_gw_get_selected_gw_node(bat_priv);
 409
 410         spin_lock_bh(&bat_priv->gw.list_lock);
 411
 412         hlist_for_each_entry_safe(gw_node, node_tmp,
 413                                   &bat_priv->gw.list, list) {
 414                 if (((!gw_node->deleted) ||
 415                      (time_before(jiffies, gw_node->deleted + timeout))) &&
 416                     atomic_read(&bat_priv->mesh_state) == BATADV_MESH_ACTIVE)
 417                         continue;
 418
 419                 if (curr_gw == gw_node)
 420                         do_deselect = 1;
 421
 422                 hlist_del_rcu(&gw_node->list);
 423                 batadv_gw_node_free_ref(gw_node);
 424         }
 425
 426         spin_unlock_bh(&bat_priv->gw.list_lock);
 427
 428         /* gw_deselect() needs to acquire the gw_list_lock */
 429         if (do_deselect)
 430                 batadv_gw_deselect(bat_priv);
 431
 432         if (curr_gw)
 433                 batadv_gw_node_free_ref(curr_gw);
 434 }
 435
 436 /* fails if orig_node has no router */
 437 static int batadv_write_buffer_text(struct batadv_priv *bat_priv,
 438                                     struct seq_file *seq,
 439                                     const struct batadv_gw_node *gw_node)
 440 {
 441         struct batadv_gw_node *curr_gw;
 442         struct batadv_neigh_node *router;
 443         int down, up, ret = -1;
 444
 445         batadv_gw_bandwidth_to_kbit(gw_node->orig_node->gw_flags, &down, &up);
 446
 447         router = batadv_orig_node_get_router(gw_node->orig_node);
 448         if (!router)
 449                 goto out;
 450
 451         curr_gw = batadv_gw_get_selected_gw_node(bat_priv);
 452
 453         ret = seq_printf(seq, "%s %pM (%3i) %pM [%10s]: %3i - %i%s/%i%s\n",
 454                          (curr_gw == gw_node ? "=>" : "  "),
 455                          gw_node->orig_node->orig,
 456                          router->tq_avg, router->addr,
 457                          router->if_incoming->net_dev->name,
 458                          gw_node->orig_node->gw_flags,
 459                          (down > 2048 ? down / 1024 : down),
 460                          (down > 2048 ? "MBit" : "KBit"),
 461                          (up > 2048 ? up / 1024 : up),
 462                          (up > 2048 ? "MBit" : "KBit"));
 463
 464         batadv_neigh_node_free_ref(router);
 465         if (curr_gw)
 466                 batadv_gw_node_free_ref(curr_gw);
 467 out:
 468         return ret;
 469 }
 470
 471 int batadv_gw_client_seq_print_text(struct seq_file *seq, void *offset)
 472 {
 473         struct net_device *net_dev = (struct net_device *)seq->private;
 474         struct batadv_priv *bat_priv = netdev_priv(net_dev);
 475         struct batadv_hard_iface *primary_if;
 476         struct batadv_gw_node *gw_node;
 477         int gw_count = 0;
 478
 479         primary_if = batadv_seq_print_text_primary_if_get(seq);
 480         if (!primary_if)
 481                 goto out;
 482
 483         seq_printf(seq,
 484                    "      %-12s (%s/%i) %17s [%10s]: gw_class ... [B.A.T.M.A.N. adv %s, MainIF/MAC: %s/%pM (%s)]\n",
 485                    "Gateway", "#", BATADV_TQ_MAX_VALUE, "Nexthop", "outgoingIF",
 486                    BATADV_SOURCE_VERSION, primary_if->net_dev->name,
 487                    primary_if->net_dev->dev_addr, net_dev->name);
 488
 489         rcu_read_lock();
 490         hlist_for_each_entry_rcu(gw_node, &bat_priv->gw.list, list) {
 491                 if (gw_node->deleted)
 492                         continue;
 493
 494                 /* fails if orig_node has no router */
 495                 if (batadv_write_buffer_text(bat_priv, seq, gw_node) < 0)
 496                         continue;
 497
 498                 gw_count++;
 499         }
 500         rcu_read_unlock();
 501
 502         if (gw_count == 0)
 503                 seq_puts(seq, "No gateways in range ...\n");
 504
 505 out:
 506         if (primary_if)
 507                 batadv_hardif_free_ref(primary_if);
 508         return 0;
 509 }
 510
 511 /* this call might reallocate skb data */
 512 static bool batadv_is_type_dhcprequest(struct sk_buff *skb, int header_len)
 513 {
 514         int ret = false;
 515         unsigned char *p;
 516         int pkt_len;
 517
 518         if (skb_linearize(skb) < 0)
 519                 goto out;
 520
 521         pkt_len = skb_headlen(skb);
 522
 523         if (pkt_len < header_len + BATADV_DHCP_OPTIONS_OFFSET + 1)
 524                 goto out;
 525
 526         p = skb->data + header_len + BATADV_DHCP_OPTIONS_OFFSET;
 527         pkt_len -= header_len + BATADV_DHCP_OPTIONS_OFFSET + 1;
 528
 529         /* Access the dhcp option lists. Each entry is made up by:
 530          * - octet 1: option type
 531          * - octet 2: option data len (only if type != 255 and 0)
 532          * - octet 3: option data
 533          */
 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                          */
 540                         if (pkt_len < 2)
 541                                 goto out;
 542                         p += 2;
 543
 544                         /* check if the message type is what we need */
 545                         if (*p == BATADV_DHCP_REQUEST)
 546                                 ret = true;
 547                         break;
 548                 } else if (*p == 0) {
 549                         /* option type 0 (padding), just go forward */
 550                         if (pkt_len < 1)
 551                                 goto out;
 552                         pkt_len--;
 553                         p++;
 554                 } else {
 555                         /* This is any other option. So we get the length... */
 556                         if (pkt_len < 1)
 557                                 goto out;
 558                         pkt_len--;
 559                         p++;
 560
 561                         /* ...and then we jump over the data */
 562                         if (pkt_len < 1 + (*p))
 563                                 goto out;
 564                         pkt_len -= 1 + (*p);
 565                         p += 1 + (*p);
 566                 }
 567         }
 568 out:
 569         return ret;
 570 }
 571
 572 /* this call might reallocate skb data */
 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
 625         /* skb->data might have been reallocated by pskb_may_pull() */
 626         ethhdr = (struct ethhdr *)skb->data;
 627         if (ntohs(ethhdr->h_proto) == ETH_P_8021Q)
 628                 ethhdr = (struct ethhdr *)(skb->data + VLAN_HLEN);
 629
 630         udphdr = (struct udphdr *)(skb->data + *header_len);
 631         *header_len += sizeof(*udphdr);
 632
 633         /* check for bootp port */
 634         if ((ntohs(ethhdr->h_proto) == ETH_P_IP) &&
 635             (ntohs(udphdr->dest) != 67))
 636                 return false;
 637
 638         if ((ntohs(ethhdr->h_proto) == ETH_P_IPV6) &&
 639             (ntohs(udphdr->dest) != 547))
 640                 return false;
 641
 642         return true;
 643 }
 644
 645 /* this call might reallocate skb data */
 646 bool batadv_gw_out_of_range(struct batadv_priv *bat_priv,
 647                             struct sk_buff *skb)
 648 {
 649         struct batadv_neigh_node *neigh_curr = NULL, *neigh_old = NULL;
 650         struct batadv_orig_node *orig_dst_node = NULL;
 651         struct batadv_gw_node *curr_gw = NULL;
 652         struct ethhdr *ethhdr;
 653         bool ret, out_of_range = false;
 654         unsigned int header_len = 0;
 655         uint8_t curr_tq_avg;
 656
 657         ret = batadv_gw_is_dhcp_target(skb, &header_len);
 658         if (!ret)
 659                 goto out;
 660
 661         ethhdr = (struct ethhdr *)skb->data;
 662         orig_dst_node = batadv_transtable_search(bat_priv, ethhdr->h_source,
 663                                                  ethhdr->h_dest);
 664         if (!orig_dst_node)
 665                 goto out;
 666
 667         if (!orig_dst_node->gw_flags)
 668                 goto out;
 669
 670         ret = batadv_is_type_dhcprequest(skb, header_len);
 671         if (!ret)
 672                 goto out;
 673
 674         switch (atomic_read(&bat_priv->gw_mode)) {
 675         case BATADV_GW_MODE_SERVER:
 676                 /* If we are a GW then we are our best GW. We can artificially
 677                  * set the tq towards ourself as the maximum value
 678                  */
 679                 curr_tq_avg = BATADV_TQ_MAX_VALUE;
 680                 break;
 681         case BATADV_GW_MODE_CLIENT:
 682                 curr_gw = batadv_gw_get_selected_gw_node(bat_priv);
 683                 if (!curr_gw)
 684                         goto out;
 685
 686                 /* packet is going to our gateway */
 687                 if (curr_gw->orig_node == orig_dst_node)
 688                         goto out;
 689
 690                 /* If the dhcp packet has been sent to a different gw,
 691                  * we have to evaluate whether the old gw is still
 692                  * reliable enough
 693                  */
 694                 neigh_curr = batadv_find_router(bat_priv, curr_gw->orig_node,
 695                                                 NULL);
 696                 if (!neigh_curr)
 697                         goto out;
 698
 699                 curr_tq_avg = neigh_curr->tq_avg;
 700                 break;
 701         case BATADV_GW_MODE_OFF:
 702         default:
 703                 goto out;
 704         }
 705
 706         neigh_old = batadv_find_router(bat_priv, orig_dst_node, NULL);
 707         if (!neigh_old)
 708                 goto out;
 709
 710         if (curr_tq_avg - neigh_old->tq_avg > BATADV_GW_THRESHOLD)
 711                 out_of_range = true;
 712
 713 out:
 714         if (orig_dst_node)
 715                 batadv_orig_node_free_ref(orig_dst_node);
 716         if (curr_gw)
 717                 batadv_gw_node_free_ref(curr_gw);
 718         if (neigh_old)
 719                 batadv_neigh_node_free_ref(neigh_old);
 720         if (neigh_curr)
 721                 batadv_neigh_node_free_ref(neigh_curr);
 722         return out_of_range;
 723 }