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 /**
 194  * batadv_gw_check_client_stop - check if client mode has been switched off
 195  * @bat_priv: the bat priv with all the soft interface information
 196  *
 197  * This function assumes the caller has checked that the gw state *is actually
 198  * changing*. This function is not supposed to be called when there is no state
 199  * change.
 200  */
 201 void batadv_gw_check_client_stop(struct batadv_priv *bat_priv)
 202 {
 203         struct batadv_gw_node *curr_gw;
 204
 205         if (atomic_read(&bat_priv->gw_mode) != BATADV_GW_MODE_CLIENT)
 206                 return;
 207
 208         curr_gw = batadv_gw_get_selected_gw_node(bat_priv);
 209         if (!curr_gw)
 210                 return;
 211
 212         /* if batman-adv is switching the gw client mode off and a gateway was
 213          * already selected, send a DEL uevent
 214          */
 215         batadv_throw_uevent(bat_priv, BATADV_UEV_GW, BATADV_UEV_DEL, NULL);
 216
 217         batadv_gw_node_free_ref(curr_gw);
 218 }
 219
 220 void batadv_gw_election(struct batadv_priv *bat_priv)
 221 {
 222         struct batadv_gw_node *curr_gw = NULL, *next_gw = NULL;
 223         struct batadv_neigh_node *router = NULL;
 224         char gw_addr[18] = { '\0' };
 225
 226         /* The batman daemon checks here if we already passed a full originator
 227          * cycle in order to make sure we don't choose the first gateway we
 228          * hear about. This check is based on the daemon's uptime which we
 229          * don't have.
 230          */
 231         if (atomic_read(&bat_priv->gw_mode) != BATADV_GW_MODE_CLIENT)
 232                 goto out;
 233
 234         curr_gw = batadv_gw_get_selected_gw_node(bat_priv);
 235
 236         if (!batadv_atomic_dec_not_zero(&bat_priv->gw.reselect) && curr_gw)
 237                 goto out;
 238
 239         next_gw = batadv_gw_get_best_gw_node(bat_priv);
 240
 241         if (curr_gw == next_gw)
 242                 goto out;
 243
 244         if (next_gw) {
 245                 sprintf(gw_addr, "%pM", next_gw->orig_node->orig);
 246
 247                 router = batadv_orig_node_get_router(next_gw->orig_node);
 248                 if (!router) {
 249                         batadv_gw_deselect(bat_priv);
 250                         goto out;
 251                 }
 252         }
 253
 254         if ((curr_gw) && (!next_gw)) {
 255                 batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
 256                            "Removing selected gateway - no gateway in range\n");
 257                 batadv_throw_uevent(bat_priv, BATADV_UEV_GW, BATADV_UEV_DEL,
 258                                     NULL);
 259         } else if ((!curr_gw) && (next_gw)) {
 260                 batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
 261                            "Adding route to gateway %pM (gw_flags: %i, tq: %i)\n",
 262                            next_gw->orig_node->orig,
 263                            next_gw->orig_node->gw_flags, router->tq_avg);
 264                 batadv_throw_uevent(bat_priv, BATADV_UEV_GW, BATADV_UEV_ADD,
 265                                     gw_addr);
 266         } else {
 267                 batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
 268                            "Changing route to gateway %pM (gw_flags: %i, tq: %i)\n",
 269                            next_gw->orig_node->orig,
 270                            next_gw->orig_node->gw_flags, router->tq_avg);
 271                 batadv_throw_uevent(bat_priv, BATADV_UEV_GW, BATADV_UEV_CHANGE,
 272                                     gw_addr);
 273         }
 274
 275         batadv_gw_select(bat_priv, next_gw);
 276
 277 out:
 278         if (curr_gw)
 279                 batadv_gw_node_free_ref(curr_gw);
 280         if (next_gw)
 281                 batadv_gw_node_free_ref(next_gw);
 282         if (router)
 283                 batadv_neigh_node_free_ref(router);
 284 }
 285
 286 void batadv_gw_check_election(struct batadv_priv *bat_priv,
 287                               struct batadv_orig_node *orig_node)
 288 {
 289         struct batadv_orig_node *curr_gw_orig;
 290         struct batadv_neigh_node *router_gw = NULL, *router_orig = NULL;
 291         uint8_t gw_tq_avg, orig_tq_avg;
 292
 293         curr_gw_orig = batadv_gw_get_selected_orig(bat_priv);
 294         if (!curr_gw_orig)
 295                 goto deselect;
 296
 297         router_gw = batadv_orig_node_get_router(curr_gw_orig);
 298         if (!router_gw)
 299                 goto deselect;
 300
 301         /* this node already is the gateway */
 302         if (curr_gw_orig == orig_node)
 303                 goto out;
 304
 305         router_orig = batadv_orig_node_get_router(orig_node);
 306         if (!router_orig)
 307                 goto out;
 308
 309         gw_tq_avg = router_gw->tq_avg;
 310         orig_tq_avg = router_orig->tq_avg;
 311
 312         /* the TQ value has to be better */
 313         if (orig_tq_avg < gw_tq_avg)
 314                 goto out;
 315
 316         /* if the routing class is greater than 3 the value tells us how much
 317          * greater the TQ value of the new gateway must be
 318          */
 319         if ((atomic_read(&bat_priv->gw_sel_class) > 3) &&
 320             (orig_tq_avg - gw_tq_avg < atomic_read(&bat_priv->gw_sel_class)))
 321                 goto out;
 322
 323         batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
 324                    "Restarting gateway selection: better gateway found (tq curr: %i, tq new: %i)\n",
 325                    gw_tq_avg, orig_tq_avg);
 326
 327 deselect:
 328         batadv_gw_deselect(bat_priv);
 329 out:
 330         if (curr_gw_orig)
 331                 batadv_orig_node_free_ref(curr_gw_orig);
 332         if (router_gw)
 333                 batadv_neigh_node_free_ref(router_gw);
 334         if (router_orig)
 335                 batadv_neigh_node_free_ref(router_orig);
 336
 337         return;
 338 }
 339
 340 static void batadv_gw_node_add(struct batadv_priv *bat_priv,
 341                                struct batadv_orig_node *orig_node,
 342                                uint8_t new_gwflags)
 343 {
 344         struct batadv_gw_node *gw_node;
 345         int down, up;
 346
 347         gw_node = kzalloc(sizeof(*gw_node), GFP_ATOMIC);
 348         if (!gw_node)
 349                 return;
 350
 351         INIT_HLIST_NODE(&gw_node->list);
 352         gw_node->orig_node = orig_node;
 353         atomic_set(&gw_node->refcount, 1);
 354
 355         spin_lock_bh(&bat_priv->gw.list_lock);
 356         hlist_add_head_rcu(&gw_node->list, &bat_priv->gw.list);
 357         spin_unlock_bh(&bat_priv->gw.list_lock);
 358
 359         batadv_gw_bandwidth_to_kbit(new_gwflags, &down, &up);
 360         batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
 361                    "Found new gateway %pM -> gw_class: %i - %i%s/%i%s\n",
 362                    orig_node->orig, new_gwflags,
 363                    (down > 2048 ? down / 1024 : down),
 364                    (down > 2048 ? "MBit" : "KBit"),
 365                    (up > 2048 ? up / 1024 : up),
 366                    (up > 2048 ? "MBit" : "KBit"));
 367 }
 368
 369 void batadv_gw_node_update(struct batadv_priv *bat_priv,
 370                            struct batadv_orig_node *orig_node,
 371                            uint8_t new_gwflags)
 372 {
 373         struct batadv_gw_node *gw_node, *curr_gw;
 374
 375         /* Note: We don't need a NULL check here, since curr_gw never gets
 376          * dereferenced. If curr_gw is NULL we also should not exit as we may
 377          * have this gateway in our list (duplication check!) even though we
 378          * have no currently selected gateway.
 379          */
 380         curr_gw = batadv_gw_get_selected_gw_node(bat_priv);
 381
 382         rcu_read_lock();
 383         hlist_for_each_entry_rcu(gw_node, &bat_priv->gw.list, list) {
 384                 if (gw_node->orig_node != orig_node)
 385                         continue;
 386
 387                 batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
 388                            "Gateway class of originator %pM changed from %i to %i\n",
 389                            orig_node->orig, gw_node->orig_node->gw_flags,
 390                            new_gwflags);
 391
 392                 gw_node->deleted = 0;
 393
 394                 if (new_gwflags == BATADV_NO_FLAGS) {
 395                         gw_node->deleted = jiffies;
 396                         batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
 397                                    "Gateway %pM removed from gateway list\n",
 398                                    orig_node->orig);
 399
 400                         if (gw_node == curr_gw)
 401                                 goto deselect;
 402                 }
 403
 404                 goto unlock;
 405         }
 406
 407         if (new_gwflags == BATADV_NO_FLAGS)
 408                 goto unlock;
 409
 410         batadv_gw_node_add(bat_priv, orig_node, new_gwflags);
 411         goto unlock;
 412
 413 deselect:
 414         batadv_gw_deselect(bat_priv);
 415 unlock:
 416         rcu_read_unlock();
 417
 418         if (curr_gw)
 419                 batadv_gw_node_free_ref(curr_gw);
 420 }
 421
 422 void batadv_gw_node_delete(struct batadv_priv *bat_priv,
 423                            struct batadv_orig_node *orig_node)
 424 {
 425         batadv_gw_node_update(bat_priv, orig_node, 0);
 426 }
 427
 428 void batadv_gw_node_purge(struct batadv_priv *bat_priv)
 429 {
 430         struct batadv_gw_node *gw_node, *curr_gw;
 431         struct hlist_node *node_tmp;
 432         unsigned long timeout = msecs_to_jiffies(2 * BATADV_PURGE_TIMEOUT);
 433         int do_deselect = 0;
 434
 435         curr_gw = batadv_gw_get_selected_gw_node(bat_priv);
 436
 437         spin_lock_bh(&bat_priv->gw.list_lock);
 438
 439         hlist_for_each_entry_safe(gw_node, node_tmp,
 440                                   &bat_priv->gw.list, list) {
 441                 if (((!gw_node->deleted) ||
 442                      (time_before(jiffies, gw_node->deleted + timeout))) &&
 443                     atomic_read(&bat_priv->mesh_state) == BATADV_MESH_ACTIVE)
 444                         continue;
 445
 446                 if (curr_gw == gw_node)
 447                         do_deselect = 1;
 448
 449                 hlist_del_rcu(&gw_node->list);
 450                 batadv_gw_node_free_ref(gw_node);
 451         }
 452
 453         spin_unlock_bh(&bat_priv->gw.list_lock);
 454
 455         /* gw_deselect() needs to acquire the gw_list_lock */
 456         if (do_deselect)
 457                 batadv_gw_deselect(bat_priv);
 458
 459         if (curr_gw)
 460                 batadv_gw_node_free_ref(curr_gw);
 461 }
 462
 463 /* fails if orig_node has no router */
 464 static int batadv_write_buffer_text(struct batadv_priv *bat_priv,
 465                                     struct seq_file *seq,
 466                                     const struct batadv_gw_node *gw_node)
 467 {
 468         struct batadv_gw_node *curr_gw;
 469         struct batadv_neigh_node *router;
 470         int down, up, ret = -1;
 471
 472         batadv_gw_bandwidth_to_kbit(gw_node->orig_node->gw_flags, &down, &up);
 473
 474         router = batadv_orig_node_get_router(gw_node->orig_node);
 475         if (!router)
 476                 goto out;
 477
 478         curr_gw = batadv_gw_get_selected_gw_node(bat_priv);
 479
 480         ret = seq_printf(seq, "%s %pM (%3i) %pM [%10s]: %3i - %i%s/%i%s\n",
 481                          (curr_gw == gw_node ? "=>" : "  "),
 482                          gw_node->orig_node->orig,
 483                          router->tq_avg, router->addr,
 484                          router->if_incoming->net_dev->name,
 485                          gw_node->orig_node->gw_flags,
 486                          (down > 2048 ? down / 1024 : down),
 487                          (down > 2048 ? "MBit" : "KBit"),
 488                          (up > 2048 ? up / 1024 : up),
 489                          (up > 2048 ? "MBit" : "KBit"));
 490
 491         batadv_neigh_node_free_ref(router);
 492         if (curr_gw)
 493                 batadv_gw_node_free_ref(curr_gw);
 494 out:
 495         return ret;
 496 }
 497
 498 int batadv_gw_client_seq_print_text(struct seq_file *seq, void *offset)
 499 {
 500         struct net_device *net_dev = (struct net_device *)seq->private;
 501         struct batadv_priv *bat_priv = netdev_priv(net_dev);
 502         struct batadv_hard_iface *primary_if;
 503         struct batadv_gw_node *gw_node;
 504         int gw_count = 0;
 505
 506         primary_if = batadv_seq_print_text_primary_if_get(seq);
 507         if (!primary_if)
 508                 goto out;
 509
 510         seq_printf(seq,
 511                    "      %-12s (%s/%i) %17s [%10s]: gw_class ... [B.A.T.M.A.N. adv %s, MainIF/MAC: %s/%pM (%s)]\n",
 512                    "Gateway", "#", BATADV_TQ_MAX_VALUE, "Nexthop", "outgoingIF",
 513                    BATADV_SOURCE_VERSION, primary_if->net_dev->name,
 514                    primary_if->net_dev->dev_addr, net_dev->name);
 515
 516         rcu_read_lock();
 517         hlist_for_each_entry_rcu(gw_node, &bat_priv->gw.list, list) {
 518                 if (gw_node->deleted)
 519                         continue;
 520
 521                 /* fails if orig_node has no router */
 522                 if (batadv_write_buffer_text(bat_priv, seq, gw_node) < 0)
 523                         continue;
 524
 525                 gw_count++;
 526         }
 527         rcu_read_unlock();
 528
 529         if (gw_count == 0)
 530                 seq_puts(seq, "No gateways in range ...\n");
 531
 532 out:
 533         if (primary_if)
 534                 batadv_hardif_free_ref(primary_if);
 535         return 0;
 536 }
 537
 538 /* this call might reallocate skb data */
 539 static bool batadv_is_type_dhcprequest(struct sk_buff *skb, int header_len)
 540 {
 541         int ret = false;
 542         unsigned char *p;
 543         int pkt_len;
 544
 545         if (skb_linearize(skb) < 0)
 546                 goto out;
 547
 548         pkt_len = skb_headlen(skb);
 549
 550         if (pkt_len < header_len + BATADV_DHCP_OPTIONS_OFFSET + 1)
 551                 goto out;
 552
 553         p = skb->data + header_len + BATADV_DHCP_OPTIONS_OFFSET;
 554         pkt_len -= header_len + BATADV_DHCP_OPTIONS_OFFSET + 1;
 555
 556         /* Access the dhcp option lists. Each entry is made up by:
 557          * - octet 1: option type
 558          * - octet 2: option data len (only if type != 255 and 0)
 559          * - octet 3: option data
 560          */
 561         while (*p != 255 && !ret) {
 562                 /* p now points to the first octet: option type */
 563                 if (*p == 53) {
 564                         /* type 53 is the message type option.
 565                          * Jump the len octet and go to the data octet
 566                          */
 567                         if (pkt_len < 2)
 568                                 goto out;
 569                         p += 2;
 570
 571                         /* check if the message type is what we need */
 572                         if (*p == BATADV_DHCP_REQUEST)
 573                                 ret = true;
 574                         break;
 575                 } else if (*p == 0) {
 576                         /* option type 0 (padding), just go forward */
 577                         if (pkt_len < 1)
 578                                 goto out;
 579                         pkt_len--;
 580                         p++;
 581                 } else {
 582                         /* This is any other option. So we get the length... */
 583                         if (pkt_len < 1)
 584                                 goto out;
 585                         pkt_len--;
 586                         p++;
 587
 588                         /* ...and then we jump over the data */
 589                         if (pkt_len < 1 + (*p))
 590                                 goto out;
 591                         pkt_len -= 1 + (*p);
 592                         p += 1 + (*p);
 593                 }
 594         }
 595 out:
 596         return ret;
 597 }
 598
 599 /* this call might reallocate skb data */
 600 bool batadv_gw_is_dhcp_target(struct sk_buff *skb, unsigned int *header_len)
 601 {
 602         struct ethhdr *ethhdr;
 603         struct iphdr *iphdr;
 604         struct ipv6hdr *ipv6hdr;
 605         struct udphdr *udphdr;
 606
 607         /* check for ethernet header */
 608         if (!pskb_may_pull(skb, *header_len + ETH_HLEN))
 609                 return false;
 610         ethhdr = (struct ethhdr *)skb->data;
 611         *header_len += ETH_HLEN;
 612
 613         /* check for initial vlan header */
 614         if (ntohs(ethhdr->h_proto) == ETH_P_8021Q) {
 615                 if (!pskb_may_pull(skb, *header_len + VLAN_HLEN))
 616                         return false;
 617                 ethhdr = (struct ethhdr *)(skb->data + VLAN_HLEN);
 618                 *header_len += VLAN_HLEN;
 619         }
 620
 621         /* check for ip header */
 622         switch (ntohs(ethhdr->h_proto)) {
 623         case ETH_P_IP:
 624                 if (!pskb_may_pull(skb, *header_len + sizeof(*iphdr)))
 625                         return false;
 626                 iphdr = (struct iphdr *)(skb->data + *header_len);
 627                 *header_len += iphdr->ihl * 4;
 628
 629                 /* check for udp header */
 630                 if (iphdr->protocol != IPPROTO_UDP)
 631                         return false;
 632
 633                 break;
 634         case ETH_P_IPV6:
 635                 if (!pskb_may_pull(skb, *header_len + sizeof(*ipv6hdr)))
 636                         return false;
 637                 ipv6hdr = (struct ipv6hdr *)(skb->data + *header_len);
 638                 *header_len += sizeof(*ipv6hdr);
 639
 640                 /* check for udp header */
 641                 if (ipv6hdr->nexthdr != IPPROTO_UDP)
 642                         return false;
 643
 644                 break;
 645         default:
 646                 return false;
 647         }
 648
 649         if (!pskb_may_pull(skb, *header_len + sizeof(*udphdr)))
 650                 return false;
 651
 652         /* skb->data might have been reallocated by pskb_may_pull() */
 653         ethhdr = (struct ethhdr *)skb->data;
 654         if (ntohs(ethhdr->h_proto) == ETH_P_8021Q)
 655                 ethhdr = (struct ethhdr *)(skb->data + VLAN_HLEN);
 656
 657         udphdr = (struct udphdr *)(skb->data + *header_len);
 658         *header_len += sizeof(*udphdr);
 659
 660         /* check for bootp port */
 661         if ((ntohs(ethhdr->h_proto) == ETH_P_IP) &&
 662             (ntohs(udphdr->dest) != 67))
 663                 return false;
 664
 665         if ((ntohs(ethhdr->h_proto) == ETH_P_IPV6) &&
 666             (ntohs(udphdr->dest) != 547))
 667                 return false;
 668
 669         return true;
 670 }
 671
 672 /* this call might reallocate skb data */
 673 bool batadv_gw_out_of_range(struct batadv_priv *bat_priv,
 674                             struct sk_buff *skb)
 675 {
 676         struct batadv_neigh_node *neigh_curr = NULL, *neigh_old = NULL;
 677         struct batadv_orig_node *orig_dst_node = NULL;
 678         struct batadv_gw_node *curr_gw = NULL;
 679         struct ethhdr *ethhdr;
 680         bool ret, out_of_range = false;
 681         unsigned int header_len = 0;
 682         uint8_t curr_tq_avg;
 683
 684         ret = batadv_gw_is_dhcp_target(skb, &header_len);
 685         if (!ret)
 686                 goto out;
 687
 688         ethhdr = (struct ethhdr *)skb->data;
 689         orig_dst_node = batadv_transtable_search(bat_priv, ethhdr->h_source,
 690                                                  ethhdr->h_dest);
 691         if (!orig_dst_node)
 692                 goto out;
 693
 694         if (!orig_dst_node->gw_flags)
 695                 goto out;
 696
 697         ret = batadv_is_type_dhcprequest(skb, header_len);
 698         if (!ret)
 699                 goto out;
 700
 701         switch (atomic_read(&bat_priv->gw_mode)) {
 702         case BATADV_GW_MODE_SERVER:
 703                 /* If we are a GW then we are our best GW. We can artificially
 704                  * set the tq towards ourself as the maximum value
 705                  */
 706                 curr_tq_avg = BATADV_TQ_MAX_VALUE;
 707                 break;
 708         case BATADV_GW_MODE_CLIENT:
 709                 curr_gw = batadv_gw_get_selected_gw_node(bat_priv);
 710                 if (!curr_gw)
 711                         goto out;
 712
 713                 /* packet is going to our gateway */
 714                 if (curr_gw->orig_node == orig_dst_node)
 715                         goto out;
 716
 717                 /* If the dhcp packet has been sent to a different gw,
 718                  * we have to evaluate whether the old gw is still
 719                  * reliable enough
 720                  */
 721                 neigh_curr = batadv_find_router(bat_priv, curr_gw->orig_node,
 722                                                 NULL);
 723                 if (!neigh_curr)
 724                         goto out;
 725
 726                 curr_tq_avg = neigh_curr->tq_avg;
 727                 break;
 728         case BATADV_GW_MODE_OFF:
 729         default:
 730                 goto out;
 731         }
 732
 733         neigh_old = batadv_find_router(bat_priv, orig_dst_node, NULL);
 734         if (!neigh_old)
 735                 goto out;
 736
 737         if (curr_tq_avg - neigh_old->tq_avg > BATADV_GW_THRESHOLD)
 738                 out_of_range = true;
 739
 740 out:
 741         if (orig_dst_node)
 742                 batadv_orig_node_free_ref(orig_dst_node);
 743         if (curr_gw)
 744                 batadv_gw_node_free_ref(curr_gw);
 745         if (neigh_old)
 746                 batadv_neigh_node_free_ref(neigh_old);
 747         if (neigh_curr)
 748                 batadv_neigh_node_free_ref(neigh_curr);
 749         return out_of_range;
 750 }