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