linux/net/batman-adv/gateway_client.c
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   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
  39static 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
  45static struct batadv_gw_node *
  46batadv_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
  58out:
  59        rcu_read_unlock();
  60        return gw_node;
  61}
  62
  63struct batadv_orig_node *
  64batadv_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
  81unlock:
  82        rcu_read_unlock();
  83out:
  84        if (gw_node)
  85                batadv_gw_node_free_ref(gw_node);
  86        return orig_node;
  87}
  88
  89static 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
 108void batadv_gw_deselect(struct batadv_priv *bat_priv)
 109{
 110        atomic_set(&bat_priv->gw.reselect, 1);
 111}
 112
 113static struct batadv_gw_node *
 114batadv_gw_get_best_gw_node(struct batadv_priv *bat_priv)
 115{
 116        struct batadv_neigh_node *router;
 117        struct hlist_node *node;
 118        struct batadv_gw_node *gw_node, *curr_gw = NULL;
 119        uint32_t max_gw_factor = 0, tmp_gw_factor = 0;
 120        uint32_t gw_divisor;
 121        uint8_t max_tq = 0;
 122        int down, up;
 123        uint8_t tq_avg;
 124        struct batadv_orig_node *orig_node;
 125
 126        gw_divisor = BATADV_TQ_LOCAL_WINDOW_SIZE * BATADV_TQ_LOCAL_WINDOW_SIZE;
 127        gw_divisor *= 64;
 128
 129        rcu_read_lock();
 130        hlist_for_each_entry_rcu(gw_node, node, &bat_priv->gw.list, list) {
 131                if (gw_node->deleted)
 132                        continue;
 133
 134                orig_node = gw_node->orig_node;
 135                router = batadv_orig_node_get_router(orig_node);
 136                if (!router)
 137                        continue;
 138
 139                if (!atomic_inc_not_zero(&gw_node->refcount))
 140                        goto next;
 141
 142                tq_avg = router->tq_avg;
 143
 144                switch (atomic_read(&bat_priv->gw_sel_class)) {
 145                case 1: /* fast connection */
 146                        batadv_gw_bandwidth_to_kbit(orig_node->gw_flags,
 147                                                    &down, &up);
 148
 149                        tmp_gw_factor = tq_avg * tq_avg * down * 100 * 100;
 150                        tmp_gw_factor /= gw_divisor;
 151
 152                        if ((tmp_gw_factor > max_gw_factor) ||
 153                            ((tmp_gw_factor == max_gw_factor) &&
 154                             (tq_avg > max_tq))) {
 155                                if (curr_gw)
 156                                        batadv_gw_node_free_ref(curr_gw);
 157                                curr_gw = gw_node;
 158                                atomic_inc(&curr_gw->refcount);
 159                        }
 160                        break;
 161
 162                default: /* 2:  stable connection (use best statistic)
 163                          * 3:  fast-switch (use best statistic but change as
 164                          *     soon as a better gateway appears)
 165                          * XX: late-switch (use best statistic but change as
 166                          *     soon as a better gateway appears which has
 167                          *     $routing_class more tq points)
 168                          */
 169                        if (tq_avg > max_tq) {
 170                                if (curr_gw)
 171                                        batadv_gw_node_free_ref(curr_gw);
 172                                curr_gw = gw_node;
 173                                atomic_inc(&curr_gw->refcount);
 174                        }
 175                        break;
 176                }
 177
 178                if (tq_avg > max_tq)
 179                        max_tq = tq_avg;
 180
 181                if (tmp_gw_factor > max_gw_factor)
 182                        max_gw_factor = tmp_gw_factor;
 183
 184                batadv_gw_node_free_ref(gw_node);
 185
 186next:
 187                batadv_neigh_node_free_ref(router);
 188        }
 189        rcu_read_unlock();
 190
 191        return curr_gw;
 192}
 193
 194void batadv_gw_election(struct batadv_priv *bat_priv)
 195{
 196        struct batadv_gw_node *curr_gw = NULL, *next_gw = NULL;
 197        struct batadv_neigh_node *router = NULL;
 198        char gw_addr[18] = { '\0' };
 199
 200        /* The batman daemon checks here if we already passed a full originator
 201         * cycle in order to make sure we don't choose the first gateway we
 202         * hear about. This check is based on the daemon's uptime which we
 203         * don't have.
 204         */
 205        if (atomic_read(&bat_priv->gw_mode) != BATADV_GW_MODE_CLIENT)
 206                goto out;
 207
 208        curr_gw = batadv_gw_get_selected_gw_node(bat_priv);
 209
 210        if (!batadv_atomic_dec_not_zero(&bat_priv->gw.reselect) && curr_gw)
 211                goto out;
 212
 213        next_gw = batadv_gw_get_best_gw_node(bat_priv);
 214
 215        if (curr_gw == next_gw)
 216                goto out;
 217
 218        if (next_gw) {
 219                sprintf(gw_addr, "%pM", next_gw->orig_node->orig);
 220
 221                router = batadv_orig_node_get_router(next_gw->orig_node);
 222                if (!router) {
 223                        batadv_gw_deselect(bat_priv);
 224                        goto out;
 225                }
 226        }
 227
 228        if ((curr_gw) && (!next_gw)) {
 229                batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
 230                           "Removing selected gateway - no gateway in range\n");
 231                batadv_throw_uevent(bat_priv, BATADV_UEV_GW, BATADV_UEV_DEL,
 232                                    NULL);
 233        } else if ((!curr_gw) && (next_gw)) {
 234                batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
 235                           "Adding route to gateway %pM (gw_flags: %i, tq: %i)\n",
 236                           next_gw->orig_node->orig,
 237                           next_gw->orig_node->gw_flags, router->tq_avg);
 238                batadv_throw_uevent(bat_priv, BATADV_UEV_GW, BATADV_UEV_ADD,
 239                                    gw_addr);
 240        } else {
 241                batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
 242                           "Changing route to gateway %pM (gw_flags: %i, tq: %i)\n",
 243                           next_gw->orig_node->orig,
 244                           next_gw->orig_node->gw_flags, router->tq_avg);
 245                batadv_throw_uevent(bat_priv, BATADV_UEV_GW, BATADV_UEV_CHANGE,
 246                                    gw_addr);
 247        }
 248
 249        batadv_gw_select(bat_priv, next_gw);
 250
 251out:
 252        if (curr_gw)
 253                batadv_gw_node_free_ref(curr_gw);
 254        if (next_gw)
 255                batadv_gw_node_free_ref(next_gw);
 256        if (router)
 257                batadv_neigh_node_free_ref(router);
 258}
 259
 260void batadv_gw_check_election(struct batadv_priv *bat_priv,
 261                              struct batadv_orig_node *orig_node)
 262{
 263        struct batadv_orig_node *curr_gw_orig;
 264        struct batadv_neigh_node *router_gw = NULL, *router_orig = NULL;
 265        uint8_t gw_tq_avg, orig_tq_avg;
 266
 267        curr_gw_orig = batadv_gw_get_selected_orig(bat_priv);
 268        if (!curr_gw_orig)
 269                goto deselect;
 270
 271        router_gw = batadv_orig_node_get_router(curr_gw_orig);
 272        if (!router_gw)
 273                goto deselect;
 274
 275        /* this node already is the gateway */
 276        if (curr_gw_orig == orig_node)
 277                goto out;
 278
 279        router_orig = batadv_orig_node_get_router(orig_node);
 280        if (!router_orig)
 281                goto out;
 282
 283        gw_tq_avg = router_gw->tq_avg;
 284        orig_tq_avg = router_orig->tq_avg;
 285
 286        /* the TQ value has to be better */
 287        if (orig_tq_avg < gw_tq_avg)
 288                goto out;
 289
 290        /* if the routing class is greater than 3 the value tells us how much
 291         * greater the TQ value of the new gateway must be
 292         */
 293        if ((atomic_read(&bat_priv->gw_sel_class) > 3) &&
 294            (orig_tq_avg - gw_tq_avg < atomic_read(&bat_priv->gw_sel_class)))
 295                goto out;
 296
 297        batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
 298                   "Restarting gateway selection: better gateway found (tq curr: %i, tq new: %i)\n",
 299                   gw_tq_avg, orig_tq_avg);
 300
 301deselect:
 302        batadv_gw_deselect(bat_priv);
 303out:
 304        if (curr_gw_orig)
 305                batadv_orig_node_free_ref(curr_gw_orig);
 306        if (router_gw)
 307                batadv_neigh_node_free_ref(router_gw);
 308        if (router_orig)
 309                batadv_neigh_node_free_ref(router_orig);
 310
 311        return;
 312}
 313
 314static void batadv_gw_node_add(struct batadv_priv *bat_priv,
 315                               struct batadv_orig_node *orig_node,
 316                               uint8_t new_gwflags)
 317{
 318        struct batadv_gw_node *gw_node;
 319        int down, up;
 320
 321        gw_node = kzalloc(sizeof(*gw_node), GFP_ATOMIC);
 322        if (!gw_node)
 323                return;
 324
 325        INIT_HLIST_NODE(&gw_node->list);
 326        gw_node->orig_node = orig_node;
 327        atomic_set(&gw_node->refcount, 1);
 328
 329        spin_lock_bh(&bat_priv->gw.list_lock);
 330        hlist_add_head_rcu(&gw_node->list, &bat_priv->gw.list);
 331        spin_unlock_bh(&bat_priv->gw.list_lock);
 332
 333        batadv_gw_bandwidth_to_kbit(new_gwflags, &down, &up);
 334        batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
 335                   "Found new gateway %pM -> gw_class: %i - %i%s/%i%s\n",
 336                   orig_node->orig, new_gwflags,
 337                   (down > 2048 ? down / 1024 : down),
 338                   (down > 2048 ? "MBit" : "KBit"),
 339                   (up > 2048 ? up / 1024 : up),
 340                   (up > 2048 ? "MBit" : "KBit"));
 341}
 342
 343void batadv_gw_node_update(struct batadv_priv *bat_priv,
 344                           struct batadv_orig_node *orig_node,
 345                           uint8_t new_gwflags)
 346{
 347        struct hlist_node *node;
 348        struct batadv_gw_node *gw_node, *curr_gw;
 349
 350        /* Note: We don't need a NULL check here, since curr_gw never gets
 351         * dereferenced. If curr_gw is NULL we also should not exit as we may
 352         * have this gateway in our list (duplication check!) even though we
 353         * have no currently selected gateway.
 354         */
 355        curr_gw = batadv_gw_get_selected_gw_node(bat_priv);
 356
 357        rcu_read_lock();
 358        hlist_for_each_entry_rcu(gw_node, node, &bat_priv->gw.list, list) {
 359                if (gw_node->orig_node != orig_node)
 360                        continue;
 361
 362                batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
 363                           "Gateway class of originator %pM changed from %i to %i\n",
 364                           orig_node->orig, gw_node->orig_node->gw_flags,
 365                           new_gwflags);
 366
 367                gw_node->deleted = 0;
 368
 369                if (new_gwflags == BATADV_NO_FLAGS) {
 370                        gw_node->deleted = jiffies;
 371                        batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
 372                                   "Gateway %pM removed from gateway list\n",
 373                                   orig_node->orig);
 374
 375                        if (gw_node == curr_gw)
 376                                goto deselect;
 377                }
 378
 379                goto unlock;
 380        }
 381
 382        if (new_gwflags == BATADV_NO_FLAGS)
 383                goto unlock;
 384
 385        batadv_gw_node_add(bat_priv, orig_node, new_gwflags);
 386        goto unlock;
 387
 388deselect:
 389        batadv_gw_deselect(bat_priv);
 390unlock:
 391        rcu_read_unlock();
 392
 393        if (curr_gw)
 394                batadv_gw_node_free_ref(curr_gw);
 395}
 396
 397void batadv_gw_node_delete(struct batadv_priv *bat_priv,
 398                           struct batadv_orig_node *orig_node)
 399{
 400        batadv_gw_node_update(bat_priv, orig_node, 0);
 401}
 402
 403void batadv_gw_node_purge(struct batadv_priv *bat_priv)
 404{
 405        struct batadv_gw_node *gw_node, *curr_gw;
 406        struct hlist_node *node, *node_tmp;
 407        unsigned long timeout = msecs_to_jiffies(2 * BATADV_PURGE_TIMEOUT);
 408        int do_deselect = 0;
 409
 410        curr_gw = batadv_gw_get_selected_gw_node(bat_priv);
 411
 412        spin_lock_bh(&bat_priv->gw.list_lock);
 413
 414        hlist_for_each_entry_safe(gw_node, node, node_tmp,
 415                                  &bat_priv->gw.list, list) {
 416                if (((!gw_node->deleted) ||
 417                     (time_before(jiffies, gw_node->deleted + timeout))) &&
 418                    atomic_read(&bat_priv->mesh_state) == BATADV_MESH_ACTIVE)
 419                        continue;
 420
 421                if (curr_gw == gw_node)
 422                        do_deselect = 1;
 423
 424                hlist_del_rcu(&gw_node->list);
 425                batadv_gw_node_free_ref(gw_node);
 426        }
 427
 428        spin_unlock_bh(&bat_priv->gw.list_lock);
 429
 430        /* gw_deselect() needs to acquire the gw_list_lock */
 431        if (do_deselect)
 432                batadv_gw_deselect(bat_priv);
 433
 434        if (curr_gw)
 435                batadv_gw_node_free_ref(curr_gw);
 436}
 437
 438/* fails if orig_node has no router */
 439static int batadv_write_buffer_text(struct batadv_priv *bat_priv,
 440                                    struct seq_file *seq,
 441                                    const struct batadv_gw_node *gw_node)
 442{
 443        struct batadv_gw_node *curr_gw;
 444        struct batadv_neigh_node *router;
 445        int down, up, ret = -1;
 446
 447        batadv_gw_bandwidth_to_kbit(gw_node->orig_node->gw_flags, &down, &up);
 448
 449        router = batadv_orig_node_get_router(gw_node->orig_node);
 450        if (!router)
 451                goto out;
 452
 453        curr_gw = batadv_gw_get_selected_gw_node(bat_priv);
 454
 455        ret = seq_printf(seq, "%s %pM (%3i) %pM [%10s]: %3i - %i%s/%i%s\n",
 456                         (curr_gw == gw_node ? "=>" : "  "),
 457                         gw_node->orig_node->orig,
 458                         router->tq_avg, router->addr,
 459                         router->if_incoming->net_dev->name,
 460                         gw_node->orig_node->gw_flags,
 461                         (down > 2048 ? down / 1024 : down),
 462                         (down > 2048 ? "MBit" : "KBit"),
 463                         (up > 2048 ? up / 1024 : up),
 464                         (up > 2048 ? "MBit" : "KBit"));
 465
 466        batadv_neigh_node_free_ref(router);
 467        if (curr_gw)
 468                batadv_gw_node_free_ref(curr_gw);
 469out:
 470        return ret;
 471}
 472
 473int batadv_gw_client_seq_print_text(struct seq_file *seq, void *offset)
 474{
 475        struct net_device *net_dev = (struct net_device *)seq->private;
 476        struct batadv_priv *bat_priv = netdev_priv(net_dev);
 477        struct batadv_hard_iface *primary_if;
 478        struct batadv_gw_node *gw_node;
 479        struct hlist_node *node;
 480        int gw_count = 0, ret = 0;
 481
 482        primary_if = batadv_primary_if_get_selected(bat_priv);
 483        if (!primary_if) {
 484                ret = seq_printf(seq,
 485                                 "BATMAN mesh %s disabled - please specify interfaces to enable it\n",
 486                                 net_dev->name);
 487                goto out;
 488        }
 489
 490        if (primary_if->if_status != BATADV_IF_ACTIVE) {
 491                ret = seq_printf(seq,
 492                                 "BATMAN mesh %s disabled - primary interface not active\n",
 493                                 net_dev->name);
 494                goto out;
 495        }
 496
 497        seq_printf(seq,
 498                   "      %-12s (%s/%i) %17s [%10s]: gw_class ... [B.A.T.M.A.N. adv %s, MainIF/MAC: %s/%pM (%s)]\n",
 499                   "Gateway", "#", BATADV_TQ_MAX_VALUE, "Nexthop", "outgoingIF",
 500                   BATADV_SOURCE_VERSION, primary_if->net_dev->name,
 501                   primary_if->net_dev->dev_addr, net_dev->name);
 502
 503        rcu_read_lock();
 504        hlist_for_each_entry_rcu(gw_node, node, &bat_priv->gw.list, list) {
 505                if (gw_node->deleted)
 506                        continue;
 507
 508                /* fails if orig_node has no router */
 509                if (batadv_write_buffer_text(bat_priv, seq, gw_node) < 0)
 510                        continue;
 511
 512                gw_count++;
 513        }
 514        rcu_read_unlock();
 515
 516        if (gw_count == 0)
 517                seq_printf(seq, "No gateways in range ...\n");
 518
 519out:
 520        if (primary_if)
 521                batadv_hardif_free_ref(primary_if);
 522        return ret;
 523}
 524
 525static bool batadv_is_type_dhcprequest(struct sk_buff *skb, int header_len)
 526{
 527        int ret = false;
 528        unsigned char *p;
 529        int pkt_len;
 530
 531        if (skb_linearize(skb) < 0)
 532                goto out;
 533
 534        pkt_len = skb_headlen(skb);
 535
 536        if (pkt_len < header_len + BATADV_DHCP_OPTIONS_OFFSET + 1)
 537                goto out;
 538
 539        p = skb->data + header_len + BATADV_DHCP_OPTIONS_OFFSET;
 540        pkt_len -= header_len + BATADV_DHCP_OPTIONS_OFFSET + 1;
 541
 542        /* Access the dhcp option lists. Each entry is made up by:
 543         * - octet 1: option type
 544         * - octet 2: option data len (only if type != 255 and 0)
 545         * - octet 3: option data
 546         */
 547        while (*p != 255 && !ret) {
 548                /* p now points to the first octet: option type */
 549                if (*p == 53) {
 550                        /* type 53 is the message type option.
 551                         * Jump the len octet and go to the data octet
 552                         */
 553                        if (pkt_len < 2)
 554                                goto out;
 555                        p += 2;
 556
 557                        /* check if the message type is what we need */
 558                        if (*p == BATADV_DHCP_REQUEST)
 559                                ret = true;
 560                        break;
 561                } else if (*p == 0) {
 562                        /* option type 0 (padding), just go forward */
 563                        if (pkt_len < 1)
 564                                goto out;
 565                        pkt_len--;
 566                        p++;
 567                } else {
 568                        /* This is any other option. So we get the length... */
 569                        if (pkt_len < 1)
 570                                goto out;
 571                        pkt_len--;
 572                        p++;
 573
 574                        /* ...and then we jump over the data */
 575                        if (pkt_len < 1 + (*p))
 576                                goto out;
 577                        pkt_len -= 1 + (*p);
 578                        p += 1 + (*p);
 579                }
 580        }
 581out:
 582        return ret;
 583}
 584
 585bool batadv_gw_is_dhcp_target(struct sk_buff *skb, unsigned int *header_len)
 586{
 587        struct ethhdr *ethhdr;
 588        struct iphdr *iphdr;
 589        struct ipv6hdr *ipv6hdr;
 590        struct udphdr *udphdr;
 591
 592        /* check for ethernet header */
 593        if (!pskb_may_pull(skb, *header_len + ETH_HLEN))
 594                return false;
 595        ethhdr = (struct ethhdr *)skb->data;
 596        *header_len += ETH_HLEN;
 597
 598        /* check for initial vlan header */
 599        if (ntohs(ethhdr->h_proto) == ETH_P_8021Q) {
 600                if (!pskb_may_pull(skb, *header_len + VLAN_HLEN))
 601                        return false;
 602                ethhdr = (struct ethhdr *)(skb->data + VLAN_HLEN);
 603                *header_len += VLAN_HLEN;
 604        }
 605
 606        /* check for ip header */
 607        switch (ntohs(ethhdr->h_proto)) {
 608        case ETH_P_IP:
 609                if (!pskb_may_pull(skb, *header_len + sizeof(*iphdr)))
 610                        return false;
 611                iphdr = (struct iphdr *)(skb->data + *header_len);
 612                *header_len += iphdr->ihl * 4;
 613
 614                /* check for udp header */
 615                if (iphdr->protocol != IPPROTO_UDP)
 616                        return false;
 617
 618                break;
 619        case ETH_P_IPV6:
 620                if (!pskb_may_pull(skb, *header_len + sizeof(*ipv6hdr)))
 621                        return false;
 622                ipv6hdr = (struct ipv6hdr *)(skb->data + *header_len);
 623                *header_len += sizeof(*ipv6hdr);
 624
 625                /* check for udp header */
 626                if (ipv6hdr->nexthdr != IPPROTO_UDP)
 627                        return false;
 628
 629                break;
 630        default:
 631                return false;
 632        }
 633
 634        if (!pskb_may_pull(skb, *header_len + sizeof(*udphdr)))
 635                return false;
 636        udphdr = (struct udphdr *)(skb->data + *header_len);
 637        *header_len += sizeof(*udphdr);
 638
 639        /* check for bootp port */
 640        if ((ntohs(ethhdr->h_proto) == ETH_P_IP) &&
 641            (ntohs(udphdr->dest) != 67))
 642                return false;
 643
 644        if ((ntohs(ethhdr->h_proto) == ETH_P_IPV6) &&
 645            (ntohs(udphdr->dest) != 547))
 646                return false;
 647
 648        return true;
 649}
 650
 651bool batadv_gw_out_of_range(struct batadv_priv *bat_priv,
 652                            struct sk_buff *skb, struct ethhdr *ethhdr)
 653{
 654        struct batadv_neigh_node *neigh_curr = NULL, *neigh_old = NULL;
 655        struct batadv_orig_node *orig_dst_node = NULL;
 656        struct batadv_gw_node *curr_gw = NULL;
 657        bool ret, out_of_range = false;
 658        unsigned int header_len = 0;
 659        uint8_t curr_tq_avg;
 660
 661        ret = batadv_gw_is_dhcp_target(skb, &header_len);
 662        if (!ret)
 663                goto out;
 664
 665        orig_dst_node = batadv_transtable_search(bat_priv, ethhdr->h_source,
 666                                                 ethhdr->h_dest);
 667        if (!orig_dst_node)
 668                goto out;
 669
 670        if (!orig_dst_node->gw_flags)
 671                goto out;
 672
 673        ret = batadv_is_type_dhcprequest(skb, header_len);
 674        if (!ret)
 675                goto out;
 676
 677        switch (atomic_read(&bat_priv->gw_mode)) {
 678        case BATADV_GW_MODE_SERVER:
 679                /* If we are a GW then we are our best GW. We can artificially
 680                 * set the tq towards ourself as the maximum value
 681                 */
 682                curr_tq_avg = BATADV_TQ_MAX_VALUE;
 683                break;
 684        case BATADV_GW_MODE_CLIENT:
 685                curr_gw = batadv_gw_get_selected_gw_node(bat_priv);
 686                if (!curr_gw)
 687                        goto out;
 688
 689                /* packet is going to our gateway */
 690                if (curr_gw->orig_node == orig_dst_node)
 691                        goto out;
 692
 693                /* If the dhcp packet has been sent to a different gw,
 694                 * we have to evaluate whether the old gw is still
 695                 * reliable enough
 696                 */
 697                neigh_curr = batadv_find_router(bat_priv, curr_gw->orig_node,
 698                                                NULL);
 699                if (!neigh_curr)
 700                        goto out;
 701
 702                curr_tq_avg = neigh_curr->tq_avg;
 703                break;
 704        case BATADV_GW_MODE_OFF:
 705        default:
 706                goto out;
 707        }
 708
 709        neigh_old = batadv_find_router(bat_priv, orig_dst_node, NULL);
 710        if (!neigh_old)
 711                goto out;
 712
 713        if (curr_tq_avg - neigh_old->tq_avg > BATADV_GW_THRESHOLD)
 714                out_of_range = true;
 715
 716out:
 717        if (orig_dst_node)
 718                batadv_orig_node_free_ref(orig_dst_node);
 719        if (curr_gw)
 720                batadv_gw_node_free_ref(curr_gw);
 721        if (neigh_old)
 722                batadv_neigh_node_free_ref(neigh_old);
 723        if (neigh_curr)
 724                batadv_neigh_node_free_ref(neigh_curr);
 725        return out_of_range;
 726}
 727
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