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, see <http://www.gnu.org/licenses/>.
  16  */
  17
  18 #include "main.h"
  19 #include "sysfs.h"
  20 #include "gateway_client.h"
  21 #include "gateway_common.h"
  22 #include "hard-interface.h"
  23 #include "originator.h"
  24 #include "translation-table.h"
  25 #include "routing.h"
  26 #include <linux/ip.h>
  27 #include <linux/ipv6.h>
  28 #include <linux/udp.h>
  29 #include <linux/if_vlan.h>
  30
  31 /* These are the offsets of the "hw type" and "hw address length" in the dhcp
  32  * packet starting at the beginning of the dhcp header
  33  */
  34 #define BATADV_DHCP_HTYPE_OFFSET        1
  35 #define BATADV_DHCP_HLEN_OFFSET         2
  36 /* Value of htype representing Ethernet */
  37 #define BATADV_DHCP_HTYPE_ETHERNET      0x01
  38 /* This is the offset of the "chaddr" field in the dhcp packet starting at the
  39  * beginning of the dhcp header
  40  */
  41 #define BATADV_DHCP_CHADDR_OFFSET       28
  42
  43 static void batadv_gw_node_free_ref(struct batadv_gw_node *gw_node)
  44 {
  45         if (atomic_dec_and_test(&gw_node->refcount))
  46                 kfree_rcu(gw_node, rcu);
  47 }
  48
  49 static struct batadv_gw_node *
  50 batadv_gw_get_selected_gw_node(struct batadv_priv *bat_priv)
  51 {
  52         struct batadv_gw_node *gw_node;
  53
  54         rcu_read_lock();
  55         gw_node = rcu_dereference(bat_priv->gw.curr_gw);
  56         if (!gw_node)
  57                 goto out;
  58
  59         if (!atomic_inc_not_zero(&gw_node->refcount))
  60                 gw_node = NULL;
  61
  62 out:
  63         rcu_read_unlock();
  64         return gw_node;
  65 }
  66
  67 struct batadv_orig_node *
  68 batadv_gw_get_selected_orig(struct batadv_priv *bat_priv)
  69 {
  70         struct batadv_gw_node *gw_node;
  71         struct batadv_orig_node *orig_node = NULL;
  72
  73         gw_node = batadv_gw_get_selected_gw_node(bat_priv);
  74         if (!gw_node)
  75                 goto out;
  76
  77         rcu_read_lock();
  78         orig_node = gw_node->orig_node;
  79         if (!orig_node)
  80                 goto unlock;
  81
  82         if (!atomic_inc_not_zero(&orig_node->refcount))
  83                 orig_node = NULL;
  84
  85 unlock:
  86         rcu_read_unlock();
  87 out:
  88         if (gw_node)
  89                 batadv_gw_node_free_ref(gw_node);
  90         return orig_node;
  91 }
  92
  93 static void batadv_gw_select(struct batadv_priv *bat_priv,
  94                              struct batadv_gw_node *new_gw_node)
  95 {
  96         struct batadv_gw_node *curr_gw_node;
  97
  98         spin_lock_bh(&bat_priv->gw.list_lock);
  99
 100         if (new_gw_node && !atomic_inc_not_zero(&new_gw_node->refcount))
 101                 new_gw_node = NULL;
 102
 103         curr_gw_node = rcu_dereference_protected(bat_priv->gw.curr_gw, 1);
 104         rcu_assign_pointer(bat_priv->gw.curr_gw, new_gw_node);
 105
 106         if (curr_gw_node)
 107                 batadv_gw_node_free_ref(curr_gw_node);
 108
 109         spin_unlock_bh(&bat_priv->gw.list_lock);
 110 }
 111
 112 /**
 113  * batadv_gw_reselect - force a gateway reselection
 114  * @bat_priv: the bat priv with all the soft interface information
 115  *
 116  * Set a flag to remind the GW component to perform a new gateway reselection.
 117  * However this function does not ensure that the current gateway is going to be
 118  * deselected. The reselection mechanism may elect the same gateway once again.
 119  *
 120  * This means that invoking batadv_gw_reselect() does not guarantee a gateway
 121  * change and therefore a uevent is not necessarily expected.
 122  */
 123 void batadv_gw_reselect(struct batadv_priv *bat_priv)
 124 {
 125         atomic_set(&bat_priv->gw.reselect, 1);
 126 }
 127
 128 static struct batadv_gw_node *
 129 batadv_gw_get_best_gw_node(struct batadv_priv *bat_priv)
 130 {
 131         struct batadv_neigh_node *router;
 132         struct batadv_gw_node *gw_node, *curr_gw = NULL;
 133         uint32_t max_gw_factor = 0, tmp_gw_factor = 0;
 134         uint32_t gw_divisor;
 135         uint8_t max_tq = 0;
 136         uint8_t tq_avg;
 137         struct batadv_orig_node *orig_node;
 138
 139         gw_divisor = BATADV_TQ_LOCAL_WINDOW_SIZE * BATADV_TQ_LOCAL_WINDOW_SIZE;
 140         gw_divisor *= 64;
 141
 142         rcu_read_lock();
 143         hlist_for_each_entry_rcu(gw_node, &bat_priv->gw.list, list) {
 144                 if (gw_node->deleted)
 145                         continue;
 146
 147                 orig_node = gw_node->orig_node;
 148                 router = batadv_orig_node_get_router(orig_node);
 149                 if (!router)
 150                         continue;
 151
 152                 if (!atomic_inc_not_zero(&gw_node->refcount))
 153                         goto next;
 154
 155                 tq_avg = router->bat_iv.tq_avg;
 156
 157                 switch (atomic_read(&bat_priv->gw_sel_class)) {
 158                 case 1: /* fast connection */
 159                         tmp_gw_factor = tq_avg * tq_avg;
 160                         tmp_gw_factor *= gw_node->bandwidth_down;
 161                         tmp_gw_factor *= 100 * 100;
 162                         tmp_gw_factor /= gw_divisor;
 163
 164                         if ((tmp_gw_factor > max_gw_factor) ||
 165                             ((tmp_gw_factor == max_gw_factor) &&
 166                              (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                 default: /* 2:  stable connection (use best statistic)
 175                           * 3:  fast-switch (use best statistic but change as
 176                           *     soon as a better gateway appears)
 177                           * XX: late-switch (use best statistic but change as
 178                           *     soon as a better gateway appears which has
 179                           *     $routing_class more tq points)
 180                           */
 181                         if (tq_avg > max_tq) {
 182                                 if (curr_gw)
 183                                         batadv_gw_node_free_ref(curr_gw);
 184                                 curr_gw = gw_node;
 185                                 atomic_inc(&curr_gw->refcount);
 186                         }
 187                         break;
 188                 }
 189
 190                 if (tq_avg > max_tq)
 191                         max_tq = tq_avg;
 192
 193                 if (tmp_gw_factor > max_gw_factor)
 194                         max_gw_factor = tmp_gw_factor;
 195
 196                 batadv_gw_node_free_ref(gw_node);
 197
 198 next:
 199                 batadv_neigh_node_free_ref(router);
 200         }
 201         rcu_read_unlock();
 202
 203         return curr_gw;
 204 }
 205
 206 /**
 207  * batadv_gw_check_client_stop - check if client mode has been switched off
 208  * @bat_priv: the bat priv with all the soft interface information
 209  *
 210  * This function assumes the caller has checked that the gw state *is actually
 211  * changing*. This function is not supposed to be called when there is no state
 212  * change.
 213  */
 214 void batadv_gw_check_client_stop(struct batadv_priv *bat_priv)
 215 {
 216         struct batadv_gw_node *curr_gw;
 217
 218         if (atomic_read(&bat_priv->gw_mode) != BATADV_GW_MODE_CLIENT)
 219                 return;
 220
 221         curr_gw = batadv_gw_get_selected_gw_node(bat_priv);
 222         if (!curr_gw)
 223                 return;
 224
 225         /* deselect the current gateway so that next time that client mode is
 226          * enabled a proper GW_ADD event can be sent
 227          */
 228         batadv_gw_select(bat_priv, NULL);
 229
 230         /* if batman-adv is switching the gw client mode off and a gateway was
 231          * already selected, send a DEL uevent
 232          */
 233         batadv_throw_uevent(bat_priv, BATADV_UEV_GW, BATADV_UEV_DEL, NULL);
 234
 235         batadv_gw_node_free_ref(curr_gw);
 236 }
 237
 238 void batadv_gw_election(struct batadv_priv *bat_priv)
 239 {
 240         struct batadv_gw_node *curr_gw = NULL, *next_gw = NULL;
 241         struct batadv_neigh_node *router = NULL;
 242         char gw_addr[18] = { '\0' };
 243
 244         if (atomic_read(&bat_priv->gw_mode) != BATADV_GW_MODE_CLIENT)
 245                 goto out;
 246
 247         curr_gw = batadv_gw_get_selected_gw_node(bat_priv);
 248
 249         if (!batadv_atomic_dec_not_zero(&bat_priv->gw.reselect) && curr_gw)
 250                 goto out;
 251
 252         next_gw = batadv_gw_get_best_gw_node(bat_priv);
 253
 254         if (curr_gw == next_gw)
 255                 goto out;
 256
 257         if (next_gw) {
 258                 sprintf(gw_addr, "%pM", next_gw->orig_node->orig);
 259
 260                 router = batadv_orig_node_get_router(next_gw->orig_node);
 261                 if (!router) {
 262                         batadv_gw_reselect(bat_priv);
 263                         goto out;
 264                 }
 265         }
 266
 267         if ((curr_gw) && (!next_gw)) {
 268                 batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
 269                            "Removing selected gateway - no gateway in range\n");
 270                 batadv_throw_uevent(bat_priv, BATADV_UEV_GW, BATADV_UEV_DEL,
 271                                     NULL);
 272         } else if ((!curr_gw) && (next_gw)) {
 273                 batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
 274                            "Adding route to gateway %pM (bandwidth: %u.%u/%u.%u MBit, tq: %i)\n",
 275                            next_gw->orig_node->orig,
 276                            next_gw->bandwidth_down / 10,
 277                            next_gw->bandwidth_down % 10,
 278                            next_gw->bandwidth_up / 10,
 279                            next_gw->bandwidth_up % 10, router->bat_iv.tq_avg);
 280                 batadv_throw_uevent(bat_priv, BATADV_UEV_GW, BATADV_UEV_ADD,
 281                                     gw_addr);
 282         } else {
 283                 batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
 284                            "Changing route to gateway %pM (bandwidth: %u.%u/%u.%u MBit, tq: %i)\n",
 285                            next_gw->orig_node->orig,
 286                            next_gw->bandwidth_down / 10,
 287                            next_gw->bandwidth_down % 10,
 288                            next_gw->bandwidth_up / 10,
 289                            next_gw->bandwidth_up % 10, router->bat_iv.tq_avg);
 290                 batadv_throw_uevent(bat_priv, BATADV_UEV_GW, BATADV_UEV_CHANGE,
 291                                     gw_addr);
 292         }
 293
 294         batadv_gw_select(bat_priv, next_gw);
 295
 296 out:
 297         if (curr_gw)
 298                 batadv_gw_node_free_ref(curr_gw);
 299         if (next_gw)
 300                 batadv_gw_node_free_ref(next_gw);
 301         if (router)
 302                 batadv_neigh_node_free_ref(router);
 303 }
 304
 305 void batadv_gw_check_election(struct batadv_priv *bat_priv,
 306                               struct batadv_orig_node *orig_node)
 307 {
 308         struct batadv_orig_node *curr_gw_orig;
 309         struct batadv_neigh_node *router_gw = NULL, *router_orig = NULL;
 310         uint8_t gw_tq_avg, orig_tq_avg;
 311
 312         curr_gw_orig = batadv_gw_get_selected_orig(bat_priv);
 313         if (!curr_gw_orig)
 314                 goto reselect;
 315
 316         router_gw = batadv_orig_node_get_router(curr_gw_orig);
 317         if (!router_gw)
 318                 goto reselect;
 319
 320         /* this node already is the gateway */
 321         if (curr_gw_orig == orig_node)
 322                 goto out;
 323
 324         router_orig = batadv_orig_node_get_router(orig_node);
 325         if (!router_orig)
 326                 goto out;
 327
 328         gw_tq_avg = router_gw->bat_iv.tq_avg;
 329         orig_tq_avg = router_orig->bat_iv.tq_avg;
 330
 331         /* the TQ value has to be better */
 332         if (orig_tq_avg < gw_tq_avg)
 333                 goto out;
 334
 335         /* if the routing class is greater than 3 the value tells us how much
 336          * greater the TQ value of the new gateway must be
 337          */
 338         if ((atomic_read(&bat_priv->gw_sel_class) > 3) &&
 339             (orig_tq_avg - gw_tq_avg < atomic_read(&bat_priv->gw_sel_class)))
 340                 goto out;
 341
 342         batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
 343                    "Restarting gateway selection: better gateway found (tq curr: %i, tq new: %i)\n",
 344                    gw_tq_avg, orig_tq_avg);
 345
 346 reselect:
 347         batadv_gw_reselect(bat_priv);
 348 out:
 349         if (curr_gw_orig)
 350                 batadv_orig_node_free_ref(curr_gw_orig);
 351         if (router_gw)
 352                 batadv_neigh_node_free_ref(router_gw);
 353         if (router_orig)
 354                 batadv_neigh_node_free_ref(router_orig);
 355
 356         return;
 357 }
 358
 359 /**
 360  * batadv_gw_node_add - add gateway node to list of available gateways
 361  * @bat_priv: the bat priv with all the soft interface information
 362  * @orig_node: originator announcing gateway capabilities
 363  * @gateway: announced bandwidth information
 364  */
 365 static void batadv_gw_node_add(struct batadv_priv *bat_priv,
 366                                struct batadv_orig_node *orig_node,
 367                                struct batadv_tvlv_gateway_data *gateway)
 368 {
 369         struct batadv_gw_node *gw_node;
 370
 371         if (gateway->bandwidth_down == 0)
 372                 return;
 373
 374         gw_node = kzalloc(sizeof(*gw_node), GFP_ATOMIC);
 375         if (!gw_node)
 376                 return;
 377
 378         INIT_HLIST_NODE(&gw_node->list);
 379         gw_node->orig_node = orig_node;
 380         atomic_set(&gw_node->refcount, 1);
 381
 382         spin_lock_bh(&bat_priv->gw.list_lock);
 383         hlist_add_head_rcu(&gw_node->list, &bat_priv->gw.list);
 384         spin_unlock_bh(&bat_priv->gw.list_lock);
 385
 386         batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
 387                    "Found new gateway %pM -> gw bandwidth: %u.%u/%u.%u MBit\n",
 388                    orig_node->orig,
 389                    ntohl(gateway->bandwidth_down) / 10,
 390                    ntohl(gateway->bandwidth_down) % 10,
 391                    ntohl(gateway->bandwidth_up) / 10,
 392                    ntohl(gateway->bandwidth_up) % 10);
 393 }
 394
 395 /**
 396  * batadv_gw_node_get - retrieve gateway node from list of available gateways
 397  * @bat_priv: the bat priv with all the soft interface information
 398  * @orig_node: originator announcing gateway capabilities
 399  *
 400  * Returns gateway node if found or NULL otherwise.
 401  */
 402 static struct batadv_gw_node *
 403 batadv_gw_node_get(struct batadv_priv *bat_priv,
 404                    struct batadv_orig_node *orig_node)
 405 {
 406         struct batadv_gw_node *gw_node_tmp, *gw_node = NULL;
 407
 408         rcu_read_lock();
 409         hlist_for_each_entry_rcu(gw_node_tmp, &bat_priv->gw.list, list) {
 410                 if (gw_node_tmp->orig_node != orig_node)
 411                         continue;
 412
 413                 if (gw_node_tmp->deleted)
 414                         continue;
 415
 416                 if (!atomic_inc_not_zero(&gw_node_tmp->refcount))
 417                         continue;
 418
 419                 gw_node = gw_node_tmp;
 420                 break;
 421         }
 422         rcu_read_unlock();
 423
 424         return gw_node;
 425 }
 426
 427 /**
 428  * batadv_gw_node_update - update list of available gateways with changed
 429  *  bandwidth information
 430  * @bat_priv: the bat priv with all the soft interface information
 431  * @orig_node: originator announcing gateway capabilities
 432  * @gateway: announced bandwidth information
 433  */
 434 void batadv_gw_node_update(struct batadv_priv *bat_priv,
 435                            struct batadv_orig_node *orig_node,
 436                            struct batadv_tvlv_gateway_data *gateway)
 437 {
 438         struct batadv_gw_node *gw_node, *curr_gw = NULL;
 439
 440         gw_node = batadv_gw_node_get(bat_priv, orig_node);
 441         if (!gw_node) {
 442                 batadv_gw_node_add(bat_priv, orig_node, gateway);
 443                 goto out;
 444         }
 445
 446         if ((gw_node->bandwidth_down == ntohl(gateway->bandwidth_down)) &&
 447             (gw_node->bandwidth_up == ntohl(gateway->bandwidth_up)))
 448                 goto out;
 449
 450         batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
 451                    "Gateway bandwidth of originator %pM changed from %u.%u/%u.%u MBit to %u.%u/%u.%u MBit\n",
 452                    orig_node->orig,
 453                    gw_node->bandwidth_down / 10,
 454                    gw_node->bandwidth_down % 10,
 455                    gw_node->bandwidth_up / 10,
 456                    gw_node->bandwidth_up % 10,
 457                    ntohl(gateway->bandwidth_down) / 10,
 458                    ntohl(gateway->bandwidth_down) % 10,
 459                    ntohl(gateway->bandwidth_up) / 10,
 460                    ntohl(gateway->bandwidth_up) % 10);
 461
 462         gw_node->bandwidth_down = ntohl(gateway->bandwidth_down);
 463         gw_node->bandwidth_up = ntohl(gateway->bandwidth_up);
 464
 465         gw_node->deleted = 0;
 466         if (ntohl(gateway->bandwidth_down) == 0) {
 467                 gw_node->deleted = jiffies;
 468                 batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
 469                            "Gateway %pM removed from gateway list\n",
 470                            orig_node->orig);
 471
 472                 /* Note: We don't need a NULL check here, since curr_gw never
 473                  * gets dereferenced.
 474                  */
 475                 curr_gw = batadv_gw_get_selected_gw_node(bat_priv);
 476                 if (gw_node == curr_gw)
 477                         batadv_gw_reselect(bat_priv);
 478         }
 479
 480 out:
 481         if (curr_gw)
 482                 batadv_gw_node_free_ref(curr_gw);
 483         if (gw_node)
 484                 batadv_gw_node_free_ref(gw_node);
 485 }
 486
 487 void batadv_gw_node_delete(struct batadv_priv *bat_priv,
 488                            struct batadv_orig_node *orig_node)
 489 {
 490         struct batadv_tvlv_gateway_data gateway;
 491
 492         gateway.bandwidth_down = 0;
 493         gateway.bandwidth_up = 0;
 494
 495         batadv_gw_node_update(bat_priv, orig_node, &gateway);
 496 }
 497
 498 void batadv_gw_node_purge(struct batadv_priv *bat_priv)
 499 {
 500         struct batadv_gw_node *gw_node, *curr_gw;
 501         struct hlist_node *node_tmp;
 502         unsigned long timeout = msecs_to_jiffies(2 * BATADV_PURGE_TIMEOUT);
 503         int do_reselect = 0;
 504
 505         curr_gw = batadv_gw_get_selected_gw_node(bat_priv);
 506
 507         spin_lock_bh(&bat_priv->gw.list_lock);
 508
 509         hlist_for_each_entry_safe(gw_node, node_tmp,
 510                                   &bat_priv->gw.list, list) {
 511                 if (((!gw_node->deleted) ||
 512                      (time_before(jiffies, gw_node->deleted + timeout))) &&
 513                     atomic_read(&bat_priv->mesh_state) == BATADV_MESH_ACTIVE)
 514                         continue;
 515
 516                 if (curr_gw == gw_node)
 517                         do_reselect = 1;
 518
 519                 hlist_del_rcu(&gw_node->list);
 520                 batadv_gw_node_free_ref(gw_node);
 521         }
 522
 523         spin_unlock_bh(&bat_priv->gw.list_lock);
 524
 525         /* gw_reselect() needs to acquire the gw_list_lock */
 526         if (do_reselect)
 527                 batadv_gw_reselect(bat_priv);
 528
 529         if (curr_gw)
 530                 batadv_gw_node_free_ref(curr_gw);
 531 }
 532
 533 /* fails if orig_node has no router */
 534 static int batadv_write_buffer_text(struct batadv_priv *bat_priv,
 535                                     struct seq_file *seq,
 536                                     const struct batadv_gw_node *gw_node)
 537 {
 538         struct batadv_gw_node *curr_gw;
 539         struct batadv_neigh_node *router;
 540         int ret = -1;
 541
 542         router = batadv_orig_node_get_router(gw_node->orig_node);
 543         if (!router)
 544                 goto out;
 545
 546         curr_gw = batadv_gw_get_selected_gw_node(bat_priv);
 547
 548         ret = seq_printf(seq, "%s %pM (%3i) %pM [%10s]: %u.%u/%u.%u MBit\n",
 549                          (curr_gw == gw_node ? "=>" : "  "),
 550                          gw_node->orig_node->orig,
 551                          router->bat_iv.tq_avg, router->addr,
 552                          router->if_incoming->net_dev->name,
 553                          gw_node->bandwidth_down / 10,
 554                          gw_node->bandwidth_down % 10,
 555                          gw_node->bandwidth_up / 10,
 556                          gw_node->bandwidth_up % 10);
 557
 558         batadv_neigh_node_free_ref(router);
 559         if (curr_gw)
 560                 batadv_gw_node_free_ref(curr_gw);
 561 out:
 562         return ret;
 563 }
 564
 565 int batadv_gw_client_seq_print_text(struct seq_file *seq, void *offset)
 566 {
 567         struct net_device *net_dev = (struct net_device *)seq->private;
 568         struct batadv_priv *bat_priv = netdev_priv(net_dev);
 569         struct batadv_hard_iface *primary_if;
 570         struct batadv_gw_node *gw_node;
 571         int gw_count = 0;
 572
 573         primary_if = batadv_seq_print_text_primary_if_get(seq);
 574         if (!primary_if)
 575                 goto out;
 576
 577         seq_printf(seq,
 578                    "      %-12s (%s/%i) %17s [%10s]: advertised uplink bandwidth ... [B.A.T.M.A.N. adv %s, MainIF/MAC: %s/%pM (%s)]\n",
 579                    "Gateway", "#", BATADV_TQ_MAX_VALUE, "Nexthop", "outgoingIF",
 580                    BATADV_SOURCE_VERSION, primary_if->net_dev->name,
 581                    primary_if->net_dev->dev_addr, net_dev->name);
 582
 583         rcu_read_lock();
 584         hlist_for_each_entry_rcu(gw_node, &bat_priv->gw.list, list) {
 585                 if (gw_node->deleted)
 586                         continue;
 587
 588                 /* fails if orig_node has no router */
 589                 if (batadv_write_buffer_text(bat_priv, seq, gw_node) < 0)
 590                         continue;
 591
 592                 gw_count++;
 593         }
 594         rcu_read_unlock();
 595
 596         if (gw_count == 0)
 597                 seq_puts(seq, "No gateways in range ...\n");
 598
 599 out:
 600         if (primary_if)
 601                 batadv_hardif_free_ref(primary_if);
 602         return 0;
 603 }
 604
 605 /**
 606  * batadv_gw_dhcp_recipient_get - check if a packet is a DHCP message
 607  * @skb: the packet to check
 608  * @header_len: a pointer to the batman-adv header size
 609  * @chaddr: buffer where the client address will be stored. Valid
 610  *  only if the function returns BATADV_DHCP_TO_CLIENT
 611  *
 612  * Returns:
 613  * - BATADV_DHCP_NO if the packet is not a dhcp message or if there was an error
 614  *   while parsing it
 615  * - BATADV_DHCP_TO_SERVER if this is a message going to the DHCP server
 616  * - BATADV_DHCP_TO_CLIENT if this is a message going to a DHCP client
 617  *
 618  * This function may re-allocate the data buffer of the skb passed as argument.
 619  */
 620 enum batadv_dhcp_recipient
 621 batadv_gw_dhcp_recipient_get(struct sk_buff *skb, unsigned int *header_len,
 622                              uint8_t *chaddr)
 623 {
 624         enum batadv_dhcp_recipient ret = BATADV_DHCP_NO;
 625         struct ethhdr *ethhdr;
 626         struct iphdr *iphdr;
 627         struct ipv6hdr *ipv6hdr;
 628         struct udphdr *udphdr;
 629         struct vlan_ethhdr *vhdr;
 630         int chaddr_offset;
 631         __be16 proto;
 632         uint8_t *p;
 633
 634         /* check for ethernet header */
 635         if (!pskb_may_pull(skb, *header_len + ETH_HLEN))
 636                 return BATADV_DHCP_NO;
 637
 638         ethhdr = (struct ethhdr *)skb->data;
 639         proto = ethhdr->h_proto;
 640         *header_len += ETH_HLEN;
 641
 642         /* check for initial vlan header */
 643         if (proto == htons(ETH_P_8021Q)) {
 644                 if (!pskb_may_pull(skb, *header_len + VLAN_HLEN))
 645                         return BATADV_DHCP_NO;
 646
 647                 vhdr = (struct vlan_ethhdr *)skb->data;
 648                 proto = vhdr->h_vlan_encapsulated_proto;
 649                 *header_len += VLAN_HLEN;
 650         }
 651
 652         /* check for ip header */
 653         switch (proto) {
 654         case htons(ETH_P_IP):
 655                 if (!pskb_may_pull(skb, *header_len + sizeof(*iphdr)))
 656                         return BATADV_DHCP_NO;
 657
 658                 iphdr = (struct iphdr *)(skb->data + *header_len);
 659                 *header_len += iphdr->ihl * 4;
 660
 661                 /* check for udp header */
 662                 if (iphdr->protocol != IPPROTO_UDP)
 663                         return BATADV_DHCP_NO;
 664
 665                 break;
 666         case htons(ETH_P_IPV6):
 667                 if (!pskb_may_pull(skb, *header_len + sizeof(*ipv6hdr)))
 668                         return BATADV_DHCP_NO;
 669
 670                 ipv6hdr = (struct ipv6hdr *)(skb->data + *header_len);
 671                 *header_len += sizeof(*ipv6hdr);
 672
 673                 /* check for udp header */
 674                 if (ipv6hdr->nexthdr != IPPROTO_UDP)
 675                         return BATADV_DHCP_NO;
 676
 677                 break;
 678         default:
 679                 return BATADV_DHCP_NO;
 680         }
 681
 682         if (!pskb_may_pull(skb, *header_len + sizeof(*udphdr)))
 683                 return BATADV_DHCP_NO;
 684
 685         /* skb->data might have been reallocated by pskb_may_pull() */
 686         ethhdr = (struct ethhdr *)skb->data;
 687         if (ntohs(ethhdr->h_proto) == ETH_P_8021Q)
 688                 ethhdr = (struct ethhdr *)(skb->data + VLAN_HLEN);
 689
 690         udphdr = (struct udphdr *)(skb->data + *header_len);
 691         *header_len += sizeof(*udphdr);
 692
 693         /* check for bootp port */
 694         switch (proto) {
 695         case htons(ETH_P_IP):
 696                 if (udphdr->dest == htons(67))
 697                         ret = BATADV_DHCP_TO_SERVER;
 698                 else if (udphdr->source == htons(67))
 699                         ret = BATADV_DHCP_TO_CLIENT;
 700                 break;
 701         case htons(ETH_P_IPV6):
 702                 if (udphdr->dest == htons(547))
 703                         ret = BATADV_DHCP_TO_SERVER;
 704                 else if (udphdr->source == htons(547))
 705                         ret = BATADV_DHCP_TO_CLIENT;
 706                 break;
 707         }
 708
 709         chaddr_offset = *header_len + BATADV_DHCP_CHADDR_OFFSET;
 710         /* store the client address if the message is going to a client */
 711         if (ret == BATADV_DHCP_TO_CLIENT &&
 712             pskb_may_pull(skb, chaddr_offset + ETH_ALEN)) {
 713                 /* check if the DHCP packet carries an Ethernet DHCP */
 714                 p = skb->data + *header_len + BATADV_DHCP_HTYPE_OFFSET;
 715                 if (*p != BATADV_DHCP_HTYPE_ETHERNET)
 716                         return BATADV_DHCP_NO;
 717
 718                 /* check if the DHCP packet carries a valid Ethernet address */
 719                 p = skb->data + *header_len + BATADV_DHCP_HLEN_OFFSET;
 720                 if (*p != ETH_ALEN)
 721                         return BATADV_DHCP_NO;
 722
 723                 memcpy(chaddr, skb->data + chaddr_offset, ETH_ALEN);
 724         }
 725
 726         return ret;
 727 }
 728 /**
 729  * batadv_gw_out_of_range - check if the dhcp request destination is the best gw
 730  * @bat_priv: the bat priv with all the soft interface information
 731  * @skb: the outgoing packet
 732  *
 733  * Check if the skb is a DHCP request and if it is sent to the current best GW
 734  * server. Due to topology changes it may be the case that the GW server
 735  * previously selected is not the best one anymore.
 736  *
 737  * Returns true if the packet destination is unicast and it is not the best gw,
 738  * false otherwise.
 739  *
 740  * This call might reallocate skb data.
 741  * Must be invoked only when the DHCP packet is going TO a DHCP SERVER.
 742  */
 743 bool batadv_gw_out_of_range(struct batadv_priv *bat_priv,
 744                             struct sk_buff *skb)
 745 {
 746         struct batadv_neigh_node *neigh_curr = NULL, *neigh_old = NULL;
 747         struct batadv_orig_node *orig_dst_node = NULL;
 748         struct batadv_gw_node *gw_node = NULL, *curr_gw = NULL;
 749         struct ethhdr *ethhdr = (struct ethhdr *)skb->data;
 750         bool out_of_range = false;
 751         uint8_t curr_tq_avg;
 752         unsigned short vid;
 753
 754         vid = batadv_get_vid(skb, 0);
 755
 756         orig_dst_node = batadv_transtable_search(bat_priv, ethhdr->h_source,
 757                                                  ethhdr->h_dest, vid);
 758         if (!orig_dst_node)
 759                 goto out;
 760
 761         gw_node = batadv_gw_node_get(bat_priv, orig_dst_node);
 762         if (!gw_node->bandwidth_down == 0)
 763                 goto out;
 764
 765         switch (atomic_read(&bat_priv->gw_mode)) {
 766         case BATADV_GW_MODE_SERVER:
 767                 /* If we are a GW then we are our best GW. We can artificially
 768                  * set the tq towards ourself as the maximum value
 769                  */
 770                 curr_tq_avg = BATADV_TQ_MAX_VALUE;
 771                 break;
 772         case BATADV_GW_MODE_CLIENT:
 773                 curr_gw = batadv_gw_get_selected_gw_node(bat_priv);
 774                 if (!curr_gw)
 775                         goto out;
 776
 777                 /* packet is going to our gateway */
 778                 if (curr_gw->orig_node == orig_dst_node)
 779                         goto out;
 780
 781                 /* If the dhcp packet has been sent to a different gw,
 782                  * we have to evaluate whether the old gw is still
 783                  * reliable enough
 784                  */
 785                 neigh_curr = batadv_find_router(bat_priv, curr_gw->orig_node,
 786                                                 NULL);
 787                 if (!neigh_curr)
 788                         goto out;
 789
 790                 curr_tq_avg = neigh_curr->bat_iv.tq_avg;
 791                 break;
 792         case BATADV_GW_MODE_OFF:
 793         default:
 794                 goto out;
 795         }
 796
 797         neigh_old = batadv_find_router(bat_priv, orig_dst_node, NULL);
 798         if (!neigh_old)
 799                 goto out;
 800
 801         if (curr_tq_avg - neigh_old->bat_iv.tq_avg > BATADV_GW_THRESHOLD)
 802                 out_of_range = true;
 803
 804 out:
 805         if (orig_dst_node)
 806                 batadv_orig_node_free_ref(orig_dst_node);
 807         if (curr_gw)
 808                 batadv_gw_node_free_ref(curr_gw);
 809         if (gw_node)
 810                 batadv_gw_node_free_ref(gw_node);
 811         if (neigh_old)
 812                 batadv_neigh_node_free_ref(neigh_old);
 813         if (neigh_curr)
 814                 batadv_neigh_node_free_ref(neigh_curr);
 815         return out_of_range;
 816 }