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         uint8_t tq_avg;
 122         struct batadv_orig_node *orig_node;
 123
 124         gw_divisor = BATADV_TQ_LOCAL_WINDOW_SIZE * BATADV_TQ_LOCAL_WINDOW_SIZE;
 125         gw_divisor *= 64;
 126
 127         rcu_read_lock();
 128         hlist_for_each_entry_rcu(gw_node, &bat_priv->gw.list, list) {
 129                 if (gw_node->deleted)
 130                         continue;
 131
 132                 orig_node = gw_node->orig_node;
 133                 router = batadv_orig_node_get_router(orig_node);
 134                 if (!router)
 135                         continue;
 136
 137                 if (!atomic_inc_not_zero(&gw_node->refcount))
 138                         goto next;
 139
 140                 tq_avg = router->bat_iv.tq_avg;
 141
 142                 switch (atomic_read(&bat_priv->gw_sel_class)) {
 143                 case 1: /* fast connection */
 144                         tmp_gw_factor = tq_avg * tq_avg;
 145                         tmp_gw_factor *= gw_node->bandwidth_down;
 146                         tmp_gw_factor *= 100 * 100;
 147                         tmp_gw_factor /= gw_divisor;
 148
 149                         if ((tmp_gw_factor > max_gw_factor) ||
 150                             ((tmp_gw_factor == max_gw_factor) &&
 151                              (tq_avg > max_tq))) {
 152                                 if (curr_gw)
 153                                         batadv_gw_node_free_ref(curr_gw);
 154                                 curr_gw = gw_node;
 155                                 atomic_inc(&curr_gw->refcount);
 156                         }
 157                         break;
 158
 159                 default: /* 2:  stable connection (use best statistic)
 160                           * 3:  fast-switch (use best statistic but change as
 161                           *     soon as a better gateway appears)
 162                           * XX: late-switch (use best statistic but change as
 163                           *     soon as a better gateway appears which has
 164                           *     $routing_class more tq points)
 165                           */
 166                         if (tq_avg > max_tq) {
 167                                 if (curr_gw)
 168                                         batadv_gw_node_free_ref(curr_gw);
 169                                 curr_gw = gw_node;
 170                                 atomic_inc(&curr_gw->refcount);
 171                         }
 172                         break;
 173                 }
 174
 175                 if (tq_avg > max_tq)
 176                         max_tq = tq_avg;
 177
 178                 if (tmp_gw_factor > max_gw_factor)
 179                         max_gw_factor = tmp_gw_factor;
 180
 181                 batadv_gw_node_free_ref(gw_node);
 182
 183 next:
 184                 batadv_neigh_node_free_ref(router);
 185         }
 186         rcu_read_unlock();
 187
 188         return curr_gw;
 189 }
 190
 191 /**
 192  * batadv_gw_check_client_stop - check if client mode has been switched off
 193  * @bat_priv: the bat priv with all the soft interface information
 194  *
 195  * This function assumes the caller has checked that the gw state *is actually
 196  * changing*. This function is not supposed to be called when there is no state
 197  * change.
 198  */
 199 void batadv_gw_check_client_stop(struct batadv_priv *bat_priv)
 200 {
 201         struct batadv_gw_node *curr_gw;
 202
 203         if (atomic_read(&bat_priv->gw_mode) != BATADV_GW_MODE_CLIENT)
 204                 return;
 205
 206         curr_gw = batadv_gw_get_selected_gw_node(bat_priv);
 207         if (!curr_gw)
 208                 return;
 209
 210         /* if batman-adv is switching the gw client mode off and a gateway was
 211          * already selected, send a DEL uevent
 212          */
 213         batadv_throw_uevent(bat_priv, BATADV_UEV_GW, BATADV_UEV_DEL, NULL);
 214
 215         batadv_gw_node_free_ref(curr_gw);
 216 }
 217
 218 void batadv_gw_election(struct batadv_priv *bat_priv)
 219 {
 220         struct batadv_gw_node *curr_gw = NULL, *next_gw = NULL;
 221         struct batadv_neigh_node *router = NULL;
 222         char gw_addr[18] = { '\0' };
 223
 224         if (atomic_read(&bat_priv->gw_mode) != BATADV_GW_MODE_CLIENT)
 225                 goto out;
 226
 227         curr_gw = batadv_gw_get_selected_gw_node(bat_priv);
 228
 229         if (!batadv_atomic_dec_not_zero(&bat_priv->gw.reselect) && curr_gw)
 230                 goto out;
 231
 232         next_gw = batadv_gw_get_best_gw_node(bat_priv);
 233
 234         if (curr_gw == next_gw)
 235                 goto out;
 236
 237         if (next_gw) {
 238                 sprintf(gw_addr, "%pM", next_gw->orig_node->orig);
 239
 240                 router = batadv_orig_node_get_router(next_gw->orig_node);
 241                 if (!router) {
 242                         batadv_gw_deselect(bat_priv);
 243                         goto out;
 244                 }
 245         }
 246
 247         if ((curr_gw) && (!next_gw)) {
 248                 batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
 249                            "Removing selected gateway - no gateway in range\n");
 250                 batadv_throw_uevent(bat_priv, BATADV_UEV_GW, BATADV_UEV_DEL,
 251                                     NULL);
 252         } else if ((!curr_gw) && (next_gw)) {
 253                 batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
 254                            "Adding route to gateway %pM (bandwidth: %u.%u/%u.%u MBit, tq: %i)\n",
 255                            next_gw->orig_node->orig,
 256                            next_gw->bandwidth_down / 10,
 257                            next_gw->bandwidth_down % 10,
 258                            next_gw->bandwidth_up / 10,
 259                            next_gw->bandwidth_up % 10, router->bat_iv.tq_avg);
 260                 batadv_throw_uevent(bat_priv, BATADV_UEV_GW, BATADV_UEV_ADD,
 261                                     gw_addr);
 262         } else {
 263                 batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
 264                            "Changing route to gateway %pM (bandwidth: %u.%u/%u.%u MBit, tq: %i)\n",
 265                            next_gw->orig_node->orig,
 266                            next_gw->bandwidth_down / 10,
 267                            next_gw->bandwidth_down % 10,
 268                            next_gw->bandwidth_up / 10,
 269                            next_gw->bandwidth_up % 10, router->bat_iv.tq_avg);
 270                 batadv_throw_uevent(bat_priv, BATADV_UEV_GW, BATADV_UEV_CHANGE,
 271                                     gw_addr);
 272         }
 273
 274         batadv_gw_select(bat_priv, next_gw);
 275
 276 out:
 277         if (curr_gw)
 278                 batadv_gw_node_free_ref(curr_gw);
 279         if (next_gw)
 280                 batadv_gw_node_free_ref(next_gw);
 281         if (router)
 282                 batadv_neigh_node_free_ref(router);
 283 }
 284
 285 void batadv_gw_check_election(struct batadv_priv *bat_priv,
 286                               struct batadv_orig_node *orig_node)
 287 {
 288         struct batadv_orig_node *curr_gw_orig;
 289         struct batadv_neigh_node *router_gw = NULL, *router_orig = NULL;
 290         uint8_t gw_tq_avg, orig_tq_avg;
 291
 292         curr_gw_orig = batadv_gw_get_selected_orig(bat_priv);
 293         if (!curr_gw_orig)
 294                 goto deselect;
 295
 296         router_gw = batadv_orig_node_get_router(curr_gw_orig);
 297         if (!router_gw)
 298                 goto deselect;
 299
 300         /* this node already is the gateway */
 301         if (curr_gw_orig == orig_node)
 302                 goto out;
 303
 304         router_orig = batadv_orig_node_get_router(orig_node);
 305         if (!router_orig)
 306                 goto out;
 307
 308         gw_tq_avg = router_gw->bat_iv.tq_avg;
 309         orig_tq_avg = router_orig->bat_iv.tq_avg;
 310
 311         /* the TQ value has to be better */
 312         if (orig_tq_avg < gw_tq_avg)
 313                 goto out;
 314
 315         /* if the routing class is greater than 3 the value tells us how much
 316          * greater the TQ value of the new gateway must be
 317          */
 318         if ((atomic_read(&bat_priv->gw_sel_class) > 3) &&
 319             (orig_tq_avg - gw_tq_avg < atomic_read(&bat_priv->gw_sel_class)))
 320                 goto out;
 321
 322         batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
 323                    "Restarting gateway selection: better gateway found (tq curr: %i, tq new: %i)\n",
 324                    gw_tq_avg, orig_tq_avg);
 325
 326 deselect:
 327         batadv_gw_deselect(bat_priv);
 328 out:
 329         if (curr_gw_orig)
 330                 batadv_orig_node_free_ref(curr_gw_orig);
 331         if (router_gw)
 332                 batadv_neigh_node_free_ref(router_gw);
 333         if (router_orig)
 334                 batadv_neigh_node_free_ref(router_orig);
 335
 336         return;
 337 }
 338
 339 /**
 340  * batadv_gw_node_add - add gateway node to list of available gateways
 341  * @bat_priv: the bat priv with all the soft interface information
 342  * @orig_node: originator announcing gateway capabilities
 343  * @gateway: announced bandwidth information
 344  */
 345 static void batadv_gw_node_add(struct batadv_priv *bat_priv,
 346                                struct batadv_orig_node *orig_node,
 347                                struct batadv_tvlv_gateway_data *gateway)
 348 {
 349         struct batadv_gw_node *gw_node;
 350
 351         if (gateway->bandwidth_down == 0)
 352                 return;
 353
 354         gw_node = kzalloc(sizeof(*gw_node), GFP_ATOMIC);
 355         if (!gw_node)
 356                 return;
 357
 358         INIT_HLIST_NODE(&gw_node->list);
 359         gw_node->orig_node = orig_node;
 360         atomic_set(&gw_node->refcount, 1);
 361
 362         spin_lock_bh(&bat_priv->gw.list_lock);
 363         hlist_add_head_rcu(&gw_node->list, &bat_priv->gw.list);
 364         spin_unlock_bh(&bat_priv->gw.list_lock);
 365
 366         batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
 367                    "Found new gateway %pM -> gw bandwidth: %u.%u/%u.%u MBit\n",
 368                    orig_node->orig,
 369                    ntohl(gateway->bandwidth_down) / 10,
 370                    ntohl(gateway->bandwidth_down) % 10,
 371                    ntohl(gateway->bandwidth_up) / 10,
 372                    ntohl(gateway->bandwidth_up) % 10);
 373 }
 374
 375 /**
 376  * batadv_gw_node_get - retrieve gateway node from list of available gateways
 377  * @bat_priv: the bat priv with all the soft interface information
 378  * @orig_node: originator announcing gateway capabilities
 379  *
 380  * Returns gateway node if found or NULL otherwise.
 381  */
 382 static struct batadv_gw_node *
 383 batadv_gw_node_get(struct batadv_priv *bat_priv,
 384                    struct batadv_orig_node *orig_node)
 385 {
 386         struct batadv_gw_node *gw_node_tmp, *gw_node = NULL;
 387
 388         rcu_read_lock();
 389         hlist_for_each_entry_rcu(gw_node_tmp, &bat_priv->gw.list, list) {
 390                 if (gw_node_tmp->orig_node != orig_node)
 391                         continue;
 392
 393                 if (gw_node_tmp->deleted)
 394                         continue;
 395
 396                 if (!atomic_inc_not_zero(&gw_node_tmp->refcount))
 397                         continue;
 398
 399                 gw_node = gw_node_tmp;
 400                 break;
 401         }
 402         rcu_read_unlock();
 403
 404         return gw_node;
 405 }
 406
 407 /**
 408  * batadv_gw_node_update - update list of available gateways with changed
 409  *  bandwidth information
 410  * @bat_priv: the bat priv with all the soft interface information
 411  * @orig_node: originator announcing gateway capabilities
 412  * @gateway: announced bandwidth information
 413  */
 414 void batadv_gw_node_update(struct batadv_priv *bat_priv,
 415                            struct batadv_orig_node *orig_node,
 416                            struct batadv_tvlv_gateway_data *gateway)
 417 {
 418         struct batadv_gw_node *gw_node, *curr_gw = NULL;
 419
 420         gw_node = batadv_gw_node_get(bat_priv, orig_node);
 421         if (!gw_node) {
 422                 batadv_gw_node_add(bat_priv, orig_node, gateway);
 423                 goto out;
 424         }
 425
 426         if ((gw_node->bandwidth_down == ntohl(gateway->bandwidth_down)) &&
 427             (gw_node->bandwidth_up == ntohl(gateway->bandwidth_up)))
 428                 goto out;
 429
 430         batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
 431                    "Gateway bandwidth of originator %pM changed from %u.%u/%u.%u MBit to %u.%u/%u.%u MBit\n",
 432                    orig_node->orig,
 433                    gw_node->bandwidth_down / 10,
 434                    gw_node->bandwidth_down % 10,
 435                    gw_node->bandwidth_up / 10,
 436                    gw_node->bandwidth_up % 10,
 437                    ntohl(gateway->bandwidth_down) / 10,
 438                    ntohl(gateway->bandwidth_down) % 10,
 439                    ntohl(gateway->bandwidth_up) / 10,
 440                    ntohl(gateway->bandwidth_up) % 10);
 441
 442         gw_node->bandwidth_down = ntohl(gateway->bandwidth_down);
 443         gw_node->bandwidth_up = ntohl(gateway->bandwidth_up);
 444
 445         gw_node->deleted = 0;
 446         if (ntohl(gateway->bandwidth_down) == 0) {
 447                 gw_node->deleted = jiffies;
 448                 batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
 449                            "Gateway %pM removed from gateway list\n",
 450                            orig_node->orig);
 451
 452                 /* Note: We don't need a NULL check here, since curr_gw never
 453                  * gets dereferenced.
 454                  */
 455                 curr_gw = batadv_gw_get_selected_gw_node(bat_priv);
 456                 if (gw_node == curr_gw)
 457                         batadv_gw_deselect(bat_priv);
 458         }
 459
 460 out:
 461         if (curr_gw)
 462                 batadv_gw_node_free_ref(curr_gw);
 463         if (gw_node)
 464                 batadv_gw_node_free_ref(gw_node);
 465 }
 466
 467 void batadv_gw_node_delete(struct batadv_priv *bat_priv,
 468                            struct batadv_orig_node *orig_node)
 469 {
 470         struct batadv_tvlv_gateway_data gateway;
 471
 472         gateway.bandwidth_down = 0;
 473         gateway.bandwidth_up = 0;
 474
 475         batadv_gw_node_update(bat_priv, orig_node, &gateway);
 476 }
 477
 478 void batadv_gw_node_purge(struct batadv_priv *bat_priv)
 479 {
 480         struct batadv_gw_node *gw_node, *curr_gw;
 481         struct hlist_node *node_tmp;
 482         unsigned long timeout = msecs_to_jiffies(2 * BATADV_PURGE_TIMEOUT);
 483         int do_deselect = 0;
 484
 485         curr_gw = batadv_gw_get_selected_gw_node(bat_priv);
 486
 487         spin_lock_bh(&bat_priv->gw.list_lock);
 488
 489         hlist_for_each_entry_safe(gw_node, node_tmp,
 490                                   &bat_priv->gw.list, list) {
 491                 if (((!gw_node->deleted) ||
 492                      (time_before(jiffies, gw_node->deleted + timeout))) &&
 493                     atomic_read(&bat_priv->mesh_state) == BATADV_MESH_ACTIVE)
 494                         continue;
 495
 496                 if (curr_gw == gw_node)
 497                         do_deselect = 1;
 498
 499                 hlist_del_rcu(&gw_node->list);
 500                 batadv_gw_node_free_ref(gw_node);
 501         }
 502
 503         spin_unlock_bh(&bat_priv->gw.list_lock);
 504
 505         /* gw_deselect() needs to acquire the gw_list_lock */
 506         if (do_deselect)
 507                 batadv_gw_deselect(bat_priv);
 508
 509         if (curr_gw)
 510                 batadv_gw_node_free_ref(curr_gw);
 511 }
 512
 513 /* fails if orig_node has no router */
 514 static int batadv_write_buffer_text(struct batadv_priv *bat_priv,
 515                                     struct seq_file *seq,
 516                                     const struct batadv_gw_node *gw_node)
 517 {
 518         struct batadv_gw_node *curr_gw;
 519         struct batadv_neigh_node *router;
 520         int ret = -1;
 521
 522         router = batadv_orig_node_get_router(gw_node->orig_node);
 523         if (!router)
 524                 goto out;
 525
 526         curr_gw = batadv_gw_get_selected_gw_node(bat_priv);
 527
 528         ret = seq_printf(seq, "%s %pM (%3i) %pM [%10s]: %u.%u/%u.%u MBit\n",
 529                          (curr_gw == gw_node ? "=>" : "  "),
 530                          gw_node->orig_node->orig,
 531                          router->bat_iv.tq_avg, router->addr,
 532                          router->if_incoming->net_dev->name,
 533                          gw_node->bandwidth_down / 10,
 534                          gw_node->bandwidth_down % 10,
 535                          gw_node->bandwidth_up / 10,
 536                          gw_node->bandwidth_up % 10);
 537
 538         batadv_neigh_node_free_ref(router);
 539         if (curr_gw)
 540                 batadv_gw_node_free_ref(curr_gw);
 541 out:
 542         return ret;
 543 }
 544
 545 int batadv_gw_client_seq_print_text(struct seq_file *seq, void *offset)
 546 {
 547         struct net_device *net_dev = (struct net_device *)seq->private;
 548         struct batadv_priv *bat_priv = netdev_priv(net_dev);
 549         struct batadv_hard_iface *primary_if;
 550         struct batadv_gw_node *gw_node;
 551         int gw_count = 0;
 552
 553         primary_if = batadv_seq_print_text_primary_if_get(seq);
 554         if (!primary_if)
 555                 goto out;
 556
 557         seq_printf(seq,
 558                    "      %-12s (%s/%i) %17s [%10s]: advertised uplink bandwidth ... [B.A.T.M.A.N. adv %s, MainIF/MAC: %s/%pM (%s)]\n",
 559                    "Gateway", "#", BATADV_TQ_MAX_VALUE, "Nexthop", "outgoingIF",
 560                    BATADV_SOURCE_VERSION, primary_if->net_dev->name,
 561                    primary_if->net_dev->dev_addr, net_dev->name);
 562
 563         rcu_read_lock();
 564         hlist_for_each_entry_rcu(gw_node, &bat_priv->gw.list, list) {
 565                 if (gw_node->deleted)
 566                         continue;
 567
 568                 /* fails if orig_node has no router */
 569                 if (batadv_write_buffer_text(bat_priv, seq, gw_node) < 0)
 570                         continue;
 571
 572                 gw_count++;
 573         }
 574         rcu_read_unlock();
 575
 576         if (gw_count == 0)
 577                 seq_puts(seq, "No gateways in range ...\n");
 578
 579 out:
 580         if (primary_if)
 581                 batadv_hardif_free_ref(primary_if);
 582         return 0;
 583 }
 584
 585 /* this call might reallocate skb data */
 586 static bool batadv_is_type_dhcprequest(struct sk_buff *skb, int header_len)
 587 {
 588         int ret = false;
 589         unsigned char *p;
 590         int pkt_len;
 591
 592         if (skb_linearize(skb) < 0)
 593                 goto out;
 594
 595         pkt_len = skb_headlen(skb);
 596
 597         if (pkt_len < header_len + BATADV_DHCP_OPTIONS_OFFSET + 1)
 598                 goto out;
 599
 600         p = skb->data + header_len + BATADV_DHCP_OPTIONS_OFFSET;
 601         pkt_len -= header_len + BATADV_DHCP_OPTIONS_OFFSET + 1;
 602
 603         /* Access the dhcp option lists. Each entry is made up by:
 604          * - octet 1: option type
 605          * - octet 2: option data len (only if type != 255 and 0)
 606          * - octet 3: option data
 607          */
 608         while (*p != 255 && !ret) {
 609                 /* p now points to the first octet: option type */
 610                 if (*p == 53) {
 611                         /* type 53 is the message type option.
 612                          * Jump the len octet and go to the data octet
 613                          */
 614                         if (pkt_len < 2)
 615                                 goto out;
 616                         p += 2;
 617
 618                         /* check if the message type is what we need */
 619                         if (*p == BATADV_DHCP_REQUEST)
 620                                 ret = true;
 621                         break;
 622                 } else if (*p == 0) {
 623                         /* option type 0 (padding), just go forward */
 624                         if (pkt_len < 1)
 625                                 goto out;
 626                         pkt_len--;
 627                         p++;
 628                 } else {
 629                         /* This is any other option. So we get the length... */
 630                         if (pkt_len < 1)
 631                                 goto out;
 632                         pkt_len--;
 633                         p++;
 634
 635                         /* ...and then we jump over the data */
 636                         if (pkt_len < 1 + (*p))
 637                                 goto out;
 638                         pkt_len -= 1 + (*p);
 639                         p += 1 + (*p);
 640                 }
 641         }
 642 out:
 643         return ret;
 644 }
 645
 646 /* this call might reallocate skb data */
 647 bool batadv_gw_is_dhcp_target(struct sk_buff *skb, unsigned int *header_len)
 648 {
 649         struct ethhdr *ethhdr;
 650         struct iphdr *iphdr;
 651         struct ipv6hdr *ipv6hdr;
 652         struct udphdr *udphdr;
 653         struct vlan_ethhdr *vhdr;
 654         __be16 proto;
 655
 656         /* check for ethernet header */
 657         if (!pskb_may_pull(skb, *header_len + ETH_HLEN))
 658                 return false;
 659         ethhdr = (struct ethhdr *)skb->data;
 660         proto = ethhdr->h_proto;
 661         *header_len += ETH_HLEN;
 662
 663         /* check for initial vlan header */
 664         if (proto == htons(ETH_P_8021Q)) {
 665                 if (!pskb_may_pull(skb, *header_len + VLAN_HLEN))
 666                         return false;
 667
 668                 vhdr = (struct vlan_ethhdr *)skb->data;
 669                 proto = vhdr->h_vlan_encapsulated_proto;
 670                 *header_len += VLAN_HLEN;
 671         }
 672
 673         /* check for ip header */
 674         switch (proto) {
 675         case htons(ETH_P_IP):
 676                 if (!pskb_may_pull(skb, *header_len + sizeof(*iphdr)))
 677                         return false;
 678                 iphdr = (struct iphdr *)(skb->data + *header_len);
 679                 *header_len += iphdr->ihl * 4;
 680
 681                 /* check for udp header */
 682                 if (iphdr->protocol != IPPROTO_UDP)
 683                         return false;
 684
 685                 break;
 686         case htons(ETH_P_IPV6):
 687                 if (!pskb_may_pull(skb, *header_len + sizeof(*ipv6hdr)))
 688                         return false;
 689                 ipv6hdr = (struct ipv6hdr *)(skb->data + *header_len);
 690                 *header_len += sizeof(*ipv6hdr);
 691
 692                 /* check for udp header */
 693                 if (ipv6hdr->nexthdr != IPPROTO_UDP)
 694                         return false;
 695
 696                 break;
 697         default:
 698                 return false;
 699         }
 700
 701         if (!pskb_may_pull(skb, *header_len + sizeof(*udphdr)))
 702                 return false;
 703
 704         /* skb->data might have been reallocated by pskb_may_pull() */
 705         ethhdr = (struct ethhdr *)skb->data;
 706         if (ntohs(ethhdr->h_proto) == ETH_P_8021Q)
 707                 ethhdr = (struct ethhdr *)(skb->data + VLAN_HLEN);
 708
 709         udphdr = (struct udphdr *)(skb->data + *header_len);
 710         *header_len += sizeof(*udphdr);
 711
 712         /* check for bootp port */
 713         if ((proto == htons(ETH_P_IP)) &&
 714             (udphdr->dest != htons(67)))
 715                 return false;
 716
 717         if ((proto == htons(ETH_P_IPV6)) &&
 718             (udphdr->dest != htons(547)))
 719                 return false;
 720
 721         return true;
 722 }
 723
 724 /**
 725  * batadv_gw_out_of_range - check if the dhcp request destination is the best gw
 726  * @bat_priv: the bat priv with all the soft interface information
 727  * @skb: the outgoing packet
 728  *
 729  * Check if the skb is a DHCP request and if it is sent to the current best GW
 730  * server. Due to topology changes it may be the case that the GW server
 731  * previously selected is not the best one anymore.
 732  *
 733  * Returns true if the packet destination is unicast and it is not the best gw,
 734  * false otherwise.
 735  *
 736  * This call might reallocate skb data.
 737  */
 738 bool batadv_gw_out_of_range(struct batadv_priv *bat_priv,
 739                             struct sk_buff *skb)
 740 {
 741         struct batadv_neigh_node *neigh_curr = NULL, *neigh_old = NULL;
 742         struct batadv_orig_node *orig_dst_node = NULL;
 743         struct batadv_gw_node *gw_node = NULL, *curr_gw = NULL;
 744         struct ethhdr *ethhdr;
 745         bool ret, out_of_range = false;
 746         unsigned int header_len = 0;
 747         uint8_t curr_tq_avg;
 748         unsigned short vid;
 749
 750         vid = batadv_get_vid(skb, 0);
 751
 752         ret = batadv_gw_is_dhcp_target(skb, &header_len);
 753         if (!ret)
 754                 goto out;
 755
 756         ethhdr = (struct ethhdr *)skb->data;
 757         orig_dst_node = batadv_transtable_search(bat_priv, ethhdr->h_source,
 758                                                  ethhdr->h_dest, vid);
 759         if (!orig_dst_node)
 760                 goto out;
 761
 762         gw_node = batadv_gw_node_get(bat_priv, orig_dst_node);
 763         if (!gw_node->bandwidth_down == 0)
 764                 goto out;
 765
 766         ret = batadv_is_type_dhcprequest(skb, header_len);
 767         if (!ret)
 768                 goto out;
 769
 770         switch (atomic_read(&bat_priv->gw_mode)) {
 771         case BATADV_GW_MODE_SERVER:
 772                 /* If we are a GW then we are our best GW. We can artificially
 773                  * set the tq towards ourself as the maximum value
 774                  */
 775                 curr_tq_avg = BATADV_TQ_MAX_VALUE;
 776                 break;
 777         case BATADV_GW_MODE_CLIENT:
 778                 curr_gw = batadv_gw_get_selected_gw_node(bat_priv);
 779                 if (!curr_gw)
 780                         goto out;
 781
 782                 /* packet is going to our gateway */
 783                 if (curr_gw->orig_node == orig_dst_node)
 784                         goto out;
 785
 786                 /* If the dhcp packet has been sent to a different gw,
 787                  * we have to evaluate whether the old gw is still
 788                  * reliable enough
 789                  */
 790                 neigh_curr = batadv_find_router(bat_priv, curr_gw->orig_node,
 791                                                 NULL);
 792                 if (!neigh_curr)
 793                         goto out;
 794
 795                 curr_tq_avg = neigh_curr->bat_iv.tq_avg;
 796                 break;
 797         case BATADV_GW_MODE_OFF:
 798         default:
 799                 goto out;
 800         }
 801
 802         neigh_old = batadv_find_router(bat_priv, orig_dst_node, NULL);
 803         if (!neigh_old)
 804                 goto out;
 805
 806         if (curr_tq_avg - neigh_old->bat_iv.tq_avg > BATADV_GW_THRESHOLD)
 807                 out_of_range = true;
 808
 809 out:
 810         if (orig_dst_node)
 811                 batadv_orig_node_free_ref(orig_dst_node);
 812         if (curr_gw)
 813                 batadv_gw_node_free_ref(curr_gw);
 814         if (gw_node)
 815                 batadv_gw_node_free_ref(gw_node);
 816         if (neigh_old)
 817                 batadv_neigh_node_free_ref(neigh_old);
 818         if (neigh_curr)
 819                 batadv_neigh_node_free_ref(neigh_curr);
 820         return out_of_range;
 821 }