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 "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 hlist_node *node;
 118         struct batadv_gw_node *gw_node, *curr_gw = NULL;
 119         uint32_t max_gw_factor = 0, tmp_gw_factor = 0;
 120         uint32_t gw_divisor;
 121         uint8_t max_tq = 0;
 122         int down, up;
 123         uint8_t tq_avg;
 124         struct batadv_orig_node *orig_node;
 125
 126         gw_divisor = BATADV_TQ_LOCAL_WINDOW_SIZE * BATADV_TQ_LOCAL_WINDOW_SIZE;
 127         gw_divisor *= 64;
 128
 129         rcu_read_lock();
 130         hlist_for_each_entry_rcu(gw_node, node, &bat_priv->gw.list, list) {
 131                 if (gw_node->deleted)
 132                         continue;
 133
 134                 orig_node = gw_node->orig_node;
 135                 router = batadv_orig_node_get_router(orig_node);
 136                 if (!router)
 137                         continue;
 138
 139                 if (!atomic_inc_not_zero(&gw_node->refcount))
 140                         goto next;
 141
 142                 tq_avg = router->tq_avg;
 143
 144                 switch (atomic_read(&bat_priv->gw_sel_class)) {
 145                 case 1: /* fast connection */
 146                         batadv_gw_bandwidth_to_kbit(orig_node->gw_flags,
 147                                                     &down, &up);
 148
 149                         tmp_gw_factor = tq_avg * tq_avg * down * 100 * 100;
 150                         tmp_gw_factor /= gw_divisor;
 151
 152                         if ((tmp_gw_factor > max_gw_factor) ||
 153                             ((tmp_gw_factor == max_gw_factor) &&
 154                              (tq_avg > max_tq))) {
 155                                 if (curr_gw)
 156                                         batadv_gw_node_free_ref(curr_gw);
 157                                 curr_gw = gw_node;
 158                                 atomic_inc(&curr_gw->refcount);
 159                         }
 160                         break;
 161
 162                 default: /* 2:  stable connection (use best statistic)
 163                           * 3:  fast-switch (use best statistic but change as
 164                           *     soon as a better gateway appears)
 165                           * XX: late-switch (use best statistic but change as
 166                           *     soon as a better gateway appears which has
 167                           *     $routing_class more tq points)
 168                           */
 169                         if (tq_avg > max_tq) {
 170                                 if (curr_gw)
 171                                         batadv_gw_node_free_ref(curr_gw);
 172                                 curr_gw = gw_node;
 173                                 atomic_inc(&curr_gw->refcount);
 174                         }
 175                         break;
 176                 }
 177
 178                 if (tq_avg > max_tq)
 179                         max_tq = tq_avg;
 180
 181                 if (tmp_gw_factor > max_gw_factor)
 182                         max_gw_factor = tmp_gw_factor;
 183
 184                 batadv_gw_node_free_ref(gw_node);
 185
 186 next:
 187                 batadv_neigh_node_free_ref(router);
 188         }
 189         rcu_read_unlock();
 190
 191         return curr_gw;
 192 }
 193
 194 void batadv_gw_election(struct batadv_priv *bat_priv)
 195 {
 196         struct batadv_gw_node *curr_gw = NULL, *next_gw = NULL;
 197         struct batadv_neigh_node *router = NULL;
 198         char gw_addr[18] = { '\0' };
 199
 200         /* The batman daemon checks here if we already passed a full originator
 201          * cycle in order to make sure we don't choose the first gateway we
 202          * hear about. This check is based on the daemon's uptime which we
 203          * don't have.
 204          */
 205         if (atomic_read(&bat_priv->gw_mode) != BATADV_GW_MODE_CLIENT)
 206                 goto out;
 207
 208         curr_gw = batadv_gw_get_selected_gw_node(bat_priv);
 209
 210         if (!batadv_atomic_dec_not_zero(&bat_priv->gw.reselect) && curr_gw)
 211                 goto out;
 212
 213         next_gw = batadv_gw_get_best_gw_node(bat_priv);
 214
 215         if (curr_gw == next_gw)
 216                 goto out;
 217
 218         if (next_gw) {
 219                 sprintf(gw_addr, "%pM", next_gw->orig_node->orig);
 220
 221                 router = batadv_orig_node_get_router(next_gw->orig_node);
 222                 if (!router) {
 223                         batadv_gw_deselect(bat_priv);
 224                         goto out;
 225                 }
 226         }
 227
 228         if ((curr_gw) && (!next_gw)) {
 229                 batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
 230                            "Removing selected gateway - no gateway in range\n");
 231                 batadv_throw_uevent(bat_priv, BATADV_UEV_GW, BATADV_UEV_DEL,
 232                                     NULL);
 233         } else if ((!curr_gw) && (next_gw)) {
 234                 batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
 235                            "Adding route to gateway %pM (gw_flags: %i, tq: %i)\n",
 236                            next_gw->orig_node->orig,
 237                            next_gw->orig_node->gw_flags, router->tq_avg);
 238                 batadv_throw_uevent(bat_priv, BATADV_UEV_GW, BATADV_UEV_ADD,
 239                                     gw_addr);
 240         } else {
 241                 batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
 242                            "Changing route to gateway %pM (gw_flags: %i, tq: %i)\n",
 243                            next_gw->orig_node->orig,
 244                            next_gw->orig_node->gw_flags, router->tq_avg);
 245                 batadv_throw_uevent(bat_priv, BATADV_UEV_GW, BATADV_UEV_CHANGE,
 246                                     gw_addr);
 247         }
 248
 249         batadv_gw_select(bat_priv, next_gw);
 250
 251 out:
 252         if (curr_gw)
 253                 batadv_gw_node_free_ref(curr_gw);
 254         if (next_gw)
 255                 batadv_gw_node_free_ref(next_gw);
 256         if (router)
 257                 batadv_neigh_node_free_ref(router);
 258 }
 259
 260 void batadv_gw_check_election(struct batadv_priv *bat_priv,
 261                               struct batadv_orig_node *orig_node)
 262 {
 263         struct batadv_orig_node *curr_gw_orig;
 264         struct batadv_neigh_node *router_gw = NULL, *router_orig = NULL;
 265         uint8_t gw_tq_avg, orig_tq_avg;
 266
 267         curr_gw_orig = batadv_gw_get_selected_orig(bat_priv);
 268         if (!curr_gw_orig)
 269                 goto deselect;
 270
 271         router_gw = batadv_orig_node_get_router(curr_gw_orig);
 272         if (!router_gw)
 273                 goto deselect;
 274
 275         /* this node already is the gateway */
 276         if (curr_gw_orig == orig_node)
 277                 goto out;
 278
 279         router_orig = batadv_orig_node_get_router(orig_node);
 280         if (!router_orig)
 281                 goto out;
 282
 283         gw_tq_avg = router_gw->tq_avg;
 284         orig_tq_avg = router_orig->tq_avg;
 285
 286         /* the TQ value has to be better */
 287         if (orig_tq_avg < gw_tq_avg)
 288                 goto out;
 289
 290         /* if the routing class is greater than 3 the value tells us how much
 291          * greater the TQ value of the new gateway must be
 292          */
 293         if ((atomic_read(&bat_priv->gw_sel_class) > 3) &&
 294             (orig_tq_avg - gw_tq_avg < atomic_read(&bat_priv->gw_sel_class)))
 295                 goto out;
 296
 297         batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
 298                    "Restarting gateway selection: better gateway found (tq curr: %i, tq new: %i)\n",
 299                    gw_tq_avg, orig_tq_avg);
 300
 301 deselect:
 302         batadv_gw_deselect(bat_priv);
 303 out:
 304         if (curr_gw_orig)
 305                 batadv_orig_node_free_ref(curr_gw_orig);
 306         if (router_gw)
 307                 batadv_neigh_node_free_ref(router_gw);
 308         if (router_orig)
 309                 batadv_neigh_node_free_ref(router_orig);
 310
 311         return;
 312 }
 313
 314 static void batadv_gw_node_add(struct batadv_priv *bat_priv,
 315                                struct batadv_orig_node *orig_node,
 316                                uint8_t new_gwflags)
 317 {
 318         struct batadv_gw_node *gw_node;
 319         int down, up;
 320
 321         gw_node = kzalloc(sizeof(*gw_node), GFP_ATOMIC);
 322         if (!gw_node)
 323                 return;
 324
 325         INIT_HLIST_NODE(&gw_node->list);
 326         gw_node->orig_node = orig_node;
 327         atomic_set(&gw_node->refcount, 1);
 328
 329         spin_lock_bh(&bat_priv->gw.list_lock);
 330         hlist_add_head_rcu(&gw_node->list, &bat_priv->gw.list);
 331         spin_unlock_bh(&bat_priv->gw.list_lock);
 332
 333         batadv_gw_bandwidth_to_kbit(new_gwflags, &down, &up);
 334         batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
 335                    "Found new gateway %pM -> gw_class: %i - %i%s/%i%s\n",
 336                    orig_node->orig, new_gwflags,
 337                    (down > 2048 ? down / 1024 : down),
 338                    (down > 2048 ? "MBit" : "KBit"),
 339                    (up > 2048 ? up / 1024 : up),
 340                    (up > 2048 ? "MBit" : "KBit"));
 341 }
 342
 343 void batadv_gw_node_update(struct batadv_priv *bat_priv,
 344                            struct batadv_orig_node *orig_node,
 345                            uint8_t new_gwflags)
 346 {
 347         struct hlist_node *node;
 348         struct batadv_gw_node *gw_node, *curr_gw;
 349
 350         /* Note: We don't need a NULL check here, since curr_gw never gets
 351          * dereferenced. If curr_gw is NULL we also should not exit as we may
 352          * have this gateway in our list (duplication check!) even though we
 353          * have no currently selected gateway.
 354          */
 355         curr_gw = batadv_gw_get_selected_gw_node(bat_priv);
 356
 357         rcu_read_lock();
 358         hlist_for_each_entry_rcu(gw_node, node, &bat_priv->gw.list, list) {
 359                 if (gw_node->orig_node != orig_node)
 360                         continue;
 361
 362                 batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
 363                            "Gateway class of originator %pM changed from %i to %i\n",
 364                            orig_node->orig, gw_node->orig_node->gw_flags,
 365                            new_gwflags);
 366
 367                 gw_node->deleted = 0;
 368
 369                 if (new_gwflags == BATADV_NO_FLAGS) {
 370                         gw_node->deleted = jiffies;
 371                         batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
 372                                    "Gateway %pM removed from gateway list\n",
 373                                    orig_node->orig);
 374
 375                         if (gw_node == curr_gw)
 376                                 goto deselect;
 377                 }
 378
 379                 goto unlock;
 380         }
 381
 382         if (new_gwflags == BATADV_NO_FLAGS)
 383                 goto unlock;
 384
 385         batadv_gw_node_add(bat_priv, orig_node, new_gwflags);
 386         goto unlock;
 387
 388 deselect:
 389         batadv_gw_deselect(bat_priv);
 390 unlock:
 391         rcu_read_unlock();
 392
 393         if (curr_gw)
 394                 batadv_gw_node_free_ref(curr_gw);
 395 }
 396
 397 void batadv_gw_node_delete(struct batadv_priv *bat_priv,
 398                            struct batadv_orig_node *orig_node)
 399 {
 400         batadv_gw_node_update(bat_priv, orig_node, 0);
 401 }
 402
 403 void batadv_gw_node_purge(struct batadv_priv *bat_priv)
 404 {
 405         struct batadv_gw_node *gw_node, *curr_gw;
 406         struct hlist_node *node, *node_tmp;
 407         unsigned long timeout = msecs_to_jiffies(2 * BATADV_PURGE_TIMEOUT);
 408         int do_deselect = 0;
 409
 410         curr_gw = batadv_gw_get_selected_gw_node(bat_priv);
 411
 412         spin_lock_bh(&bat_priv->gw.list_lock);
 413
 414         hlist_for_each_entry_safe(gw_node, node, node_tmp,
 415                                   &bat_priv->gw.list, list) {
 416                 if (((!gw_node->deleted) ||
 417                      (time_before(jiffies, gw_node->deleted + timeout))) &&
 418                     atomic_read(&bat_priv->mesh_state) == BATADV_MESH_ACTIVE)
 419                         continue;
 420
 421                 if (curr_gw == gw_node)
 422                         do_deselect = 1;
 423
 424                 hlist_del_rcu(&gw_node->list);
 425                 batadv_gw_node_free_ref(gw_node);
 426         }
 427
 428         spin_unlock_bh(&bat_priv->gw.list_lock);
 429
 430         /* gw_deselect() needs to acquire the gw_list_lock */
 431         if (do_deselect)
 432                 batadv_gw_deselect(bat_priv);
 433
 434         if (curr_gw)
 435                 batadv_gw_node_free_ref(curr_gw);
 436 }
 437
 438 /* fails if orig_node has no router */
 439 static int batadv_write_buffer_text(struct batadv_priv *bat_priv,
 440                                     struct seq_file *seq,
 441                                     const struct batadv_gw_node *gw_node)
 442 {
 443         struct batadv_gw_node *curr_gw;
 444         struct batadv_neigh_node *router;
 445         int down, up, ret = -1;
 446
 447         batadv_gw_bandwidth_to_kbit(gw_node->orig_node->gw_flags, &down, &up);
 448
 449         router = batadv_orig_node_get_router(gw_node->orig_node);
 450         if (!router)
 451                 goto out;
 452
 453         curr_gw = batadv_gw_get_selected_gw_node(bat_priv);
 454
 455         ret = seq_printf(seq, "%s %pM (%3i) %pM [%10s]: %3i - %i%s/%i%s\n",
 456                          (curr_gw == gw_node ? "=>" : "  "),
 457                          gw_node->orig_node->orig,
 458                          router->tq_avg, router->addr,
 459                          router->if_incoming->net_dev->name,
 460                          gw_node->orig_node->gw_flags,
 461                          (down > 2048 ? down / 1024 : down),
 462                          (down > 2048 ? "MBit" : "KBit"),
 463                          (up > 2048 ? up / 1024 : up),
 464                          (up > 2048 ? "MBit" : "KBit"));
 465
 466         batadv_neigh_node_free_ref(router);
 467         if (curr_gw)
 468                 batadv_gw_node_free_ref(curr_gw);
 469 out:
 470         return ret;
 471 }
 472
 473 int batadv_gw_client_seq_print_text(struct seq_file *seq, void *offset)
 474 {
 475         struct net_device *net_dev = (struct net_device *)seq->private;
 476         struct batadv_priv *bat_priv = netdev_priv(net_dev);
 477         struct batadv_hard_iface *primary_if;
 478         struct batadv_gw_node *gw_node;
 479         struct hlist_node *node;
 480         int gw_count = 0, ret = 0;
 481
 482         primary_if = batadv_primary_if_get_selected(bat_priv);
 483         if (!primary_if) {
 484                 ret = seq_printf(seq,
 485                                  "BATMAN mesh %s disabled - please specify interfaces to enable it\n",
 486                                  net_dev->name);
 487                 goto out;
 488         }
 489
 490         if (primary_if->if_status != BATADV_IF_ACTIVE) {
 491                 ret = seq_printf(seq,
 492                                  "BATMAN mesh %s disabled - primary interface not active\n",
 493                                  net_dev->name);
 494                 goto out;
 495         }
 496
 497         seq_printf(seq,
 498                    "      %-12s (%s/%i) %17s [%10s]: gw_class ... [B.A.T.M.A.N. adv %s, MainIF/MAC: %s/%pM (%s)]\n",
 499                    "Gateway", "#", BATADV_TQ_MAX_VALUE, "Nexthop", "outgoingIF",
 500                    BATADV_SOURCE_VERSION, primary_if->net_dev->name,
 501                    primary_if->net_dev->dev_addr, net_dev->name);
 502
 503         rcu_read_lock();
 504         hlist_for_each_entry_rcu(gw_node, node, &bat_priv->gw.list, list) {
 505                 if (gw_node->deleted)
 506                         continue;
 507
 508                 /* fails if orig_node has no router */
 509                 if (batadv_write_buffer_text(bat_priv, seq, gw_node) < 0)
 510                         continue;
 511
 512                 gw_count++;
 513         }
 514         rcu_read_unlock();
 515
 516         if (gw_count == 0)
 517                 seq_printf(seq, "No gateways in range ...\n");
 518
 519 out:
 520         if (primary_if)
 521                 batadv_hardif_free_ref(primary_if);
 522         return ret;
 523 }
 524
 525 static bool batadv_is_type_dhcprequest(struct sk_buff *skb, int header_len)
 526 {
 527         int ret = false;
 528         unsigned char *p;
 529         int pkt_len;
 530
 531         if (skb_linearize(skb) < 0)
 532                 goto out;
 533
 534         pkt_len = skb_headlen(skb);
 535
 536         if (pkt_len < header_len + BATADV_DHCP_OPTIONS_OFFSET + 1)
 537                 goto out;
 538
 539         p = skb->data + header_len + BATADV_DHCP_OPTIONS_OFFSET;
 540         pkt_len -= header_len + BATADV_DHCP_OPTIONS_OFFSET + 1;
 541
 542         /* Access the dhcp option lists. Each entry is made up by:
 543          * - octet 1: option type
 544          * - octet 2: option data len (only if type != 255 and 0)
 545          * - octet 3: option data
 546          */
 547         while (*p != 255 && !ret) {
 548                 /* p now points to the first octet: option type */
 549                 if (*p == 53) {
 550                         /* type 53 is the message type option.
 551                          * Jump the len octet and go to the data octet
 552                          */
 553                         if (pkt_len < 2)
 554                                 goto out;
 555                         p += 2;
 556
 557                         /* check if the message type is what we need */
 558                         if (*p == BATADV_DHCP_REQUEST)
 559                                 ret = true;
 560                         break;
 561                 } else if (*p == 0) {
 562                         /* option type 0 (padding), just go forward */
 563                         if (pkt_len < 1)
 564                                 goto out;
 565                         pkt_len--;
 566                         p++;
 567                 } else {
 568                         /* This is any other option. So we get the length... */
 569                         if (pkt_len < 1)
 570                                 goto out;
 571                         pkt_len--;
 572                         p++;
 573
 574                         /* ...and then we jump over the data */
 575                         if (pkt_len < 1 + (*p))
 576                                 goto out;
 577                         pkt_len -= 1 + (*p);
 578                         p += 1 + (*p);
 579                 }
 580         }
 581 out:
 582         return ret;
 583 }
 584
 585 bool batadv_gw_is_dhcp_target(struct sk_buff *skb, unsigned int *header_len)
 586 {
 587         struct ethhdr *ethhdr;
 588         struct iphdr *iphdr;
 589         struct ipv6hdr *ipv6hdr;
 590         struct udphdr *udphdr;
 591
 592         /* check for ethernet header */
 593         if (!pskb_may_pull(skb, *header_len + ETH_HLEN))
 594                 return false;
 595         ethhdr = (struct ethhdr *)skb->data;
 596         *header_len += ETH_HLEN;
 597
 598         /* check for initial vlan header */
 599         if (ntohs(ethhdr->h_proto) == ETH_P_8021Q) {
 600                 if (!pskb_may_pull(skb, *header_len + VLAN_HLEN))
 601                         return false;
 602                 ethhdr = (struct ethhdr *)(skb->data + VLAN_HLEN);
 603                 *header_len += VLAN_HLEN;
 604         }
 605
 606         /* check for ip header */
 607         switch (ntohs(ethhdr->h_proto)) {
 608         case ETH_P_IP:
 609                 if (!pskb_may_pull(skb, *header_len + sizeof(*iphdr)))
 610                         return false;
 611                 iphdr = (struct iphdr *)(skb->data + *header_len);
 612                 *header_len += iphdr->ihl * 4;
 613
 614                 /* check for udp header */
 615                 if (iphdr->protocol != IPPROTO_UDP)
 616                         return false;
 617
 618                 break;
 619         case ETH_P_IPV6:
 620                 if (!pskb_may_pull(skb, *header_len + sizeof(*ipv6hdr)))
 621                         return false;
 622                 ipv6hdr = (struct ipv6hdr *)(skb->data + *header_len);
 623                 *header_len += sizeof(*ipv6hdr);
 624
 625                 /* check for udp header */
 626                 if (ipv6hdr->nexthdr != IPPROTO_UDP)
 627                         return false;
 628
 629                 break;
 630         default:
 631                 return false;
 632         }
 633
 634         if (!pskb_may_pull(skb, *header_len + sizeof(*udphdr)))
 635                 return false;
 636         udphdr = (struct udphdr *)(skb->data + *header_len);
 637         *header_len += sizeof(*udphdr);
 638
 639         /* check for bootp port */
 640         if ((ntohs(ethhdr->h_proto) == ETH_P_IP) &&
 641             (ntohs(udphdr->dest) != 67))
 642                 return false;
 643
 644         if ((ntohs(ethhdr->h_proto) == ETH_P_IPV6) &&
 645             (ntohs(udphdr->dest) != 547))
 646                 return false;
 647
 648         return true;
 649 }
 650
 651 bool batadv_gw_out_of_range(struct batadv_priv *bat_priv,
 652                             struct sk_buff *skb, struct ethhdr *ethhdr)
 653 {
 654         struct batadv_neigh_node *neigh_curr = NULL, *neigh_old = NULL;
 655         struct batadv_orig_node *orig_dst_node = NULL;
 656         struct batadv_gw_node *curr_gw = NULL;
 657         bool ret, out_of_range = false;
 658         unsigned int header_len = 0;
 659         uint8_t curr_tq_avg;
 660
 661         ret = batadv_gw_is_dhcp_target(skb, &header_len);
 662         if (!ret)
 663                 goto out;
 664
 665         orig_dst_node = batadv_transtable_search(bat_priv, ethhdr->h_source,
 666                                                  ethhdr->h_dest);
 667         if (!orig_dst_node)
 668                 goto out;
 669
 670         if (!orig_dst_node->gw_flags)
 671                 goto out;
 672
 673         ret = batadv_is_type_dhcprequest(skb, header_len);
 674         if (!ret)
 675                 goto out;
 676
 677         switch (atomic_read(&bat_priv->gw_mode)) {
 678         case BATADV_GW_MODE_SERVER:
 679                 /* If we are a GW then we are our best GW. We can artificially
 680                  * set the tq towards ourself as the maximum value
 681                  */
 682                 curr_tq_avg = BATADV_TQ_MAX_VALUE;
 683                 break;
 684         case BATADV_GW_MODE_CLIENT:
 685                 curr_gw = batadv_gw_get_selected_gw_node(bat_priv);
 686                 if (!curr_gw)
 687                         goto out;
 688
 689                 /* packet is going to our gateway */
 690                 if (curr_gw->orig_node == orig_dst_node)
 691                         goto out;
 692
 693                 /* If the dhcp packet has been sent to a different gw,
 694                  * we have to evaluate whether the old gw is still
 695                  * reliable enough
 696                  */
 697                 neigh_curr = batadv_find_router(bat_priv, curr_gw->orig_node,
 698                                                 NULL);
 699                 if (!neigh_curr)
 700                         goto out;
 701
 702                 curr_tq_avg = neigh_curr->tq_avg;
 703                 break;
 704         case BATADV_GW_MODE_OFF:
 705         default:
 706                 goto out;
 707         }
 708
 709         neigh_old = batadv_find_router(bat_priv, orig_dst_node, NULL);
 710         if (!neigh_old)
 711                 goto out;
 712
 713         if (curr_tq_avg - neigh_old->tq_avg > BATADV_GW_THRESHOLD)
 714                 out_of_range = true;
 715
 716 out:
 717         if (orig_dst_node)
 718                 batadv_orig_node_free_ref(orig_dst_node);
 719         if (curr_gw)
 720                 batadv_gw_node_free_ref(curr_gw);
 721         if (neigh_old)
 722                 batadv_neigh_node_free_ref(neigh_old);
 723         if (neigh_curr)
 724                 batadv_neigh_node_free_ref(neigh_curr);
 725         return out_of_range;
 726 }