Initial import

1 files changed, 881 insertions, 0 deletions

diff --git a/net/batman-adv/gateway_client.c b/net/batman-adv/gateway_client.c
new file mode 100644
index 000000000..090828cf1
--- /dev/null
+++ b/net/batman-adv/gateway_client.c
@@ -0,0 +1,881 @@
+/* Copyright (C) 2009-2014 B.A.T.M.A.N. contributors:
+ *
+ * Marek Lindner
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of version 2 of the GNU General Public
+ * License as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "main.h"
+#include "sysfs.h"
+#include "gateway_client.h"
+#include "gateway_common.h"
+#include "hard-interface.h"
+#include "originator.h"
+#include "translation-table.h"
+#include "routing.h"
+#include <linux/ip.h>
+#include <linux/ipv6.h>
+#include <linux/udp.h>
+#include <linux/if_vlan.h>
+
+/* These are the offsets of the "hw type" and "hw address length" in the dhcp
+ * packet starting at the beginning of the dhcp header
+ */
+#define BATADV_DHCP_HTYPE_OFFSET	1
+#define BATADV_DHCP_HLEN_OFFSET		2
+/* Value of htype representing Ethernet */
+#define BATADV_DHCP_HTYPE_ETHERNET	0x01
+/* This is the offset of the "chaddr" field in the dhcp packet starting at the
+ * beginning of the dhcp header
+ */
+#define BATADV_DHCP_CHADDR_OFFSET	28
+
+static void batadv_gw_node_free_ref(struct batadv_gw_node *gw_node)
+{
+	if (atomic_dec_and_test(&gw_node->refcount)) {
+		batadv_orig_node_free_ref(gw_node->orig_node);
+		kfree_rcu(gw_node, rcu);
+	}
+}
+
+static struct batadv_gw_node *
+batadv_gw_get_selected_gw_node(struct batadv_priv *bat_priv)
+{
+	struct batadv_gw_node *gw_node;
+
+	rcu_read_lock();
+	gw_node = rcu_dereference(bat_priv->gw.curr_gw);
+	if (!gw_node)
+		goto out;
+
+	if (!atomic_inc_not_zero(&gw_node->refcount))
+		gw_node = NULL;
+
+out:
+	rcu_read_unlock();
+	return gw_node;
+}
+
+struct batadv_orig_node *
+batadv_gw_get_selected_orig(struct batadv_priv *bat_priv)
+{
+	struct batadv_gw_node *gw_node;
+	struct batadv_orig_node *orig_node = NULL;
+
+	gw_node = batadv_gw_get_selected_gw_node(bat_priv);
+	if (!gw_node)
+		goto out;
+
+	rcu_read_lock();
+	orig_node = gw_node->orig_node;
+	if (!orig_node)
+		goto unlock;
+
+	if (!atomic_inc_not_zero(&orig_node->refcount))
+		orig_node = NULL;
+
+unlock:
+	rcu_read_unlock();
+out:
+	if (gw_node)
+		batadv_gw_node_free_ref(gw_node);
+	return orig_node;
+}
+
+static void batadv_gw_select(struct batadv_priv *bat_priv,
+			     struct batadv_gw_node *new_gw_node)
+{
+	struct batadv_gw_node *curr_gw_node;
+
+	spin_lock_bh(&bat_priv->gw.list_lock);
+
+	if (new_gw_node && !atomic_inc_not_zero(&new_gw_node->refcount))
+		new_gw_node = NULL;
+
+	curr_gw_node = rcu_dereference_protected(bat_priv->gw.curr_gw, 1);
+	rcu_assign_pointer(bat_priv->gw.curr_gw, new_gw_node);
+
+	if (curr_gw_node)
+		batadv_gw_node_free_ref(curr_gw_node);
+
+	spin_unlock_bh(&bat_priv->gw.list_lock);
+}
+
+/**
+ * batadv_gw_reselect - force a gateway reselection
+ * @bat_priv: the bat priv with all the soft interface information
+ *
+ * Set a flag to remind the GW component to perform a new gateway reselection.
+ * However this function does not ensure that the current gateway is going to be
+ * deselected. The reselection mechanism may elect the same gateway once again.
+ *
+ * This means that invoking batadv_gw_reselect() does not guarantee a gateway
+ * change and therefore a uevent is not necessarily expected.
+ */
+void batadv_gw_reselect(struct batadv_priv *bat_priv)
+{
+	atomic_set(&bat_priv->gw.reselect, 1);
+}
+
+static struct batadv_gw_node *
+batadv_gw_get_best_gw_node(struct batadv_priv *bat_priv)
+{
+	struct batadv_neigh_node *router;
+	struct batadv_neigh_ifinfo *router_ifinfo;
+	struct batadv_gw_node *gw_node, *curr_gw = NULL;
+	uint32_t max_gw_factor = 0, tmp_gw_factor = 0;
+	uint32_t gw_divisor;
+	uint8_t max_tq = 0;
+	uint8_t tq_avg;
+	struct batadv_orig_node *orig_node;
+
+	gw_divisor = BATADV_TQ_LOCAL_WINDOW_SIZE * BATADV_TQ_LOCAL_WINDOW_SIZE;
+	gw_divisor *= 64;
+
+	rcu_read_lock();
+	hlist_for_each_entry_rcu(gw_node, &bat_priv->gw.list, list) {
+		if (gw_node->deleted)
+			continue;
+
+		orig_node = gw_node->orig_node;
+		router = batadv_orig_router_get(orig_node, BATADV_IF_DEFAULT);
+		if (!router)
+			continue;
+
+		router_ifinfo = batadv_neigh_ifinfo_get(router,
+							BATADV_IF_DEFAULT);
+		if (!router_ifinfo)
+			goto next;
+
+		if (!atomic_inc_not_zero(&gw_node->refcount))
+			goto next;
+
+		tq_avg = router_ifinfo->bat_iv.tq_avg;
+
+		switch (atomic_read(&bat_priv->gw_sel_class)) {
+		case 1: /* fast connection */
+			tmp_gw_factor = tq_avg * tq_avg;
+			tmp_gw_factor *= gw_node->bandwidth_down;
+			tmp_gw_factor *= 100 * 100;
+			tmp_gw_factor /= gw_divisor;
+
+			if ((tmp_gw_factor > max_gw_factor) ||
+			    ((tmp_gw_factor == max_gw_factor) &&
+			     (tq_avg > max_tq))) {
+				if (curr_gw)
+					batadv_gw_node_free_ref(curr_gw);
+				curr_gw = gw_node;
+				atomic_inc(&curr_gw->refcount);
+			}
+			break;
+
+		default: /* 2:  stable connection (use best statistic)
+			  * 3:  fast-switch (use best statistic but change as
+			  *     soon as a better gateway appears)
+			  * XX: late-switch (use best statistic but change as
+			  *     soon as a better gateway appears which has
+			  *     $routing_class more tq points)
+			  */
+			if (tq_avg > max_tq) {
+				if (curr_gw)
+					batadv_gw_node_free_ref(curr_gw);
+				curr_gw = gw_node;
+				atomic_inc(&curr_gw->refcount);
+			}
+			break;
+		}
+
+		if (tq_avg > max_tq)
+			max_tq = tq_avg;
+
+		if (tmp_gw_factor > max_gw_factor)
+			max_gw_factor = tmp_gw_factor;
+
+		batadv_gw_node_free_ref(gw_node);
+
+next:
+		batadv_neigh_node_free_ref(router);
+		if (router_ifinfo)
+			batadv_neigh_ifinfo_free_ref(router_ifinfo);
+	}
+	rcu_read_unlock();
+
+	return curr_gw;
+}
+
+/**
+ * batadv_gw_check_client_stop - check if client mode has been switched off
+ * @bat_priv: the bat priv with all the soft interface information
+ *
+ * This function assumes the caller has checked that the gw state *is actually
+ * changing*. This function is not supposed to be called when there is no state
+ * change.
+ */
+void batadv_gw_check_client_stop(struct batadv_priv *bat_priv)
+{
+	struct batadv_gw_node *curr_gw;
+
+	if (atomic_read(&bat_priv->gw_mode) != BATADV_GW_MODE_CLIENT)
+		return;
+
+	curr_gw = batadv_gw_get_selected_gw_node(bat_priv);
+	if (!curr_gw)
+		return;
+
+	/* deselect the current gateway so that next time that client mode is
+	 * enabled a proper GW_ADD event can be sent
+	 */
+	batadv_gw_select(bat_priv, NULL);
+
+	/* if batman-adv is switching the gw client mode off and a gateway was
+	 * already selected, send a DEL uevent
+	 */
+	batadv_throw_uevent(bat_priv, BATADV_UEV_GW, BATADV_UEV_DEL, NULL);
+
+	batadv_gw_node_free_ref(curr_gw);
+}
+
+void batadv_gw_election(struct batadv_priv *bat_priv)
+{
+	struct batadv_gw_node *curr_gw = NULL, *next_gw = NULL;
+	struct batadv_neigh_node *router = NULL;
+	struct batadv_neigh_ifinfo *router_ifinfo = NULL;
+	char gw_addr[18] = { '\0' };
+
+	if (atomic_read(&bat_priv->gw_mode) != BATADV_GW_MODE_CLIENT)
+		goto out;
+
+	curr_gw = batadv_gw_get_selected_gw_node(bat_priv);
+
+	if (!batadv_atomic_dec_not_zero(&bat_priv->gw.reselect) && curr_gw)
+		goto out;
+
+	next_gw = batadv_gw_get_best_gw_node(bat_priv);
+
+	if (curr_gw == next_gw)
+		goto out;
+
+	if (next_gw) {
+		sprintf(gw_addr, "%pM", next_gw->orig_node->orig);
+
+		router = batadv_orig_router_get(next_gw->orig_node,
+						BATADV_IF_DEFAULT);
+		if (!router) {
+			batadv_gw_reselect(bat_priv);
+			goto out;
+		}
+
+		router_ifinfo = batadv_neigh_ifinfo_get(router,
+							BATADV_IF_DEFAULT);
+		if (!router_ifinfo) {
+			batadv_gw_reselect(bat_priv);
+			goto out;
+		}
+	}
+
+	if ((curr_gw) && (!next_gw)) {
+		batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
+			   "Removing selected gateway - no gateway in range\n");
+		batadv_throw_uevent(bat_priv, BATADV_UEV_GW, BATADV_UEV_DEL,
+				    NULL);
+	} else if ((!curr_gw) && (next_gw)) {
+		batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
+			   "Adding route to gateway %pM (bandwidth: %u.%u/%u.%u MBit, tq: %i)\n",
+			   next_gw->orig_node->orig,
+			   next_gw->bandwidth_down / 10,
+			   next_gw->bandwidth_down % 10,
+			   next_gw->bandwidth_up / 10,
+			   next_gw->bandwidth_up % 10,
+			   router_ifinfo->bat_iv.tq_avg);
+		batadv_throw_uevent(bat_priv, BATADV_UEV_GW, BATADV_UEV_ADD,
+				    gw_addr);
+	} else {
+		batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
+			   "Changing route to gateway %pM (bandwidth: %u.%u/%u.%u MBit, tq: %i)\n",
+			   next_gw->orig_node->orig,
+			   next_gw->bandwidth_down / 10,
+			   next_gw->bandwidth_down % 10,
+			   next_gw->bandwidth_up / 10,
+			   next_gw->bandwidth_up % 10,
+			   router_ifinfo->bat_iv.tq_avg);
+		batadv_throw_uevent(bat_priv, BATADV_UEV_GW, BATADV_UEV_CHANGE,
+				    gw_addr);
+	}
+
+	batadv_gw_select(bat_priv, next_gw);
+
+out:
+	if (curr_gw)
+		batadv_gw_node_free_ref(curr_gw);
+	if (next_gw)
+		batadv_gw_node_free_ref(next_gw);
+	if (router)
+		batadv_neigh_node_free_ref(router);
+	if (router_ifinfo)
+		batadv_neigh_ifinfo_free_ref(router_ifinfo);
+}
+
+void batadv_gw_check_election(struct batadv_priv *bat_priv,
+			      struct batadv_orig_node *orig_node)
+{
+	struct batadv_neigh_ifinfo *router_orig_tq = NULL;
+	struct batadv_neigh_ifinfo *router_gw_tq = NULL;
+	struct batadv_orig_node *curr_gw_orig;
+	struct batadv_neigh_node *router_gw = NULL, *router_orig = NULL;
+	uint8_t gw_tq_avg, orig_tq_avg;
+
+	curr_gw_orig = batadv_gw_get_selected_orig(bat_priv);
+	if (!curr_gw_orig)
+		goto reselect;
+
+	router_gw = batadv_orig_router_get(curr_gw_orig, BATADV_IF_DEFAULT);
+	if (!router_gw)
+		goto reselect;
+
+	router_gw_tq = batadv_neigh_ifinfo_get(router_gw,
+					       BATADV_IF_DEFAULT);
+	if (!router_gw_tq)
+		goto reselect;
+
+	/* this node already is the gateway */
+	if (curr_gw_orig == orig_node)
+		goto out;
+
+	router_orig = batadv_orig_router_get(orig_node, BATADV_IF_DEFAULT);
+	if (!router_orig)
+		goto out;
+
+	router_orig_tq = batadv_neigh_ifinfo_get(router_orig,
+						 BATADV_IF_DEFAULT);
+	if (!router_orig_tq)
+		goto out;
+
+	gw_tq_avg = router_gw_tq->bat_iv.tq_avg;
+	orig_tq_avg = router_orig_tq->bat_iv.tq_avg;
+
+	/* the TQ value has to be better */
+	if (orig_tq_avg < gw_tq_avg)
+		goto out;
+
+	/* if the routing class is greater than 3 the value tells us how much
+	 * greater the TQ value of the new gateway must be
+	 */
+	if ((atomic_read(&bat_priv->gw_sel_class) > 3) &&
+	    (orig_tq_avg - gw_tq_avg < atomic_read(&bat_priv->gw_sel_class)))
+		goto out;
+
+	batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
+		   "Restarting gateway selection: better gateway found (tq curr: %i, tq new: %i)\n",
+		   gw_tq_avg, orig_tq_avg);
+
+reselect:
+	batadv_gw_reselect(bat_priv);
+out:
+	if (curr_gw_orig)
+		batadv_orig_node_free_ref(curr_gw_orig);
+	if (router_gw)
+		batadv_neigh_node_free_ref(router_gw);
+	if (router_orig)
+		batadv_neigh_node_free_ref(router_orig);
+	if (router_gw_tq)
+		batadv_neigh_ifinfo_free_ref(router_gw_tq);
+	if (router_orig_tq)
+		batadv_neigh_ifinfo_free_ref(router_orig_tq);
+}
+
+/**
+ * batadv_gw_node_add - add gateway node to list of available gateways
+ * @bat_priv: the bat priv with all the soft interface information
+ * @orig_node: originator announcing gateway capabilities
+ * @gateway: announced bandwidth information
+ */
+static void batadv_gw_node_add(struct batadv_priv *bat_priv,
+			       struct batadv_orig_node *orig_node,
+			       struct batadv_tvlv_gateway_data *gateway)
+{
+	struct batadv_gw_node *gw_node;
+
+	if (gateway->bandwidth_down == 0)
+		return;
+
+	if (!atomic_inc_not_zero(&orig_node->refcount))
+		return;
+
+	gw_node = kzalloc(sizeof(*gw_node), GFP_ATOMIC);
+	if (!gw_node) {
+		batadv_orig_node_free_ref(orig_node);
+		return;
+	}
+
+	INIT_HLIST_NODE(&gw_node->list);
+	gw_node->orig_node = orig_node;
+	atomic_set(&gw_node->refcount, 1);
+
+	spin_lock_bh(&bat_priv->gw.list_lock);
+	hlist_add_head_rcu(&gw_node->list, &bat_priv->gw.list);
+	spin_unlock_bh(&bat_priv->gw.list_lock);
+
+	batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
+		   "Found new gateway %pM -> gw bandwidth: %u.%u/%u.%u MBit\n",
+		   orig_node->orig,
+		   ntohl(gateway->bandwidth_down) / 10,
+		   ntohl(gateway->bandwidth_down) % 10,
+		   ntohl(gateway->bandwidth_up) / 10,
+		   ntohl(gateway->bandwidth_up) % 10);
+}
+
+/**
+ * batadv_gw_node_get - retrieve gateway node from list of available gateways
+ * @bat_priv: the bat priv with all the soft interface information
+ * @orig_node: originator announcing gateway capabilities
+ *
+ * Returns gateway node if found or NULL otherwise.
+ */
+static struct batadv_gw_node *
+batadv_gw_node_get(struct batadv_priv *bat_priv,
+		   struct batadv_orig_node *orig_node)
+{
+	struct batadv_gw_node *gw_node_tmp, *gw_node = NULL;
+
+	rcu_read_lock();
+	hlist_for_each_entry_rcu(gw_node_tmp, &bat_priv->gw.list, list) {
+		if (gw_node_tmp->orig_node != orig_node)
+			continue;
+
+		if (gw_node_tmp->deleted)
+			continue;
+
+		if (!atomic_inc_not_zero(&gw_node_tmp->refcount))
+			continue;
+
+		gw_node = gw_node_tmp;
+		break;
+	}
+	rcu_read_unlock();
+
+	return gw_node;
+}
+
+/**
+ * batadv_gw_node_update - update list of available gateways with changed
+ *  bandwidth information
+ * @bat_priv: the bat priv with all the soft interface information
+ * @orig_node: originator announcing gateway capabilities
+ * @gateway: announced bandwidth information
+ */
+void batadv_gw_node_update(struct batadv_priv *bat_priv,
+			   struct batadv_orig_node *orig_node,
+			   struct batadv_tvlv_gateway_data *gateway)
+{
+	struct batadv_gw_node *gw_node, *curr_gw = NULL;
+
+	gw_node = batadv_gw_node_get(bat_priv, orig_node);
+	if (!gw_node) {
+		batadv_gw_node_add(bat_priv, orig_node, gateway);
+		goto out;
+	}
+
+	if ((gw_node->bandwidth_down == ntohl(gateway->bandwidth_down)) &&
+	    (gw_node->bandwidth_up == ntohl(gateway->bandwidth_up)))
+		goto out;
+
+	batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
+		   "Gateway bandwidth of originator %pM changed from %u.%u/%u.%u MBit to %u.%u/%u.%u MBit\n",
+		   orig_node->orig,
+		   gw_node->bandwidth_down / 10,
+		   gw_node->bandwidth_down % 10,
+		   gw_node->bandwidth_up / 10,
+		   gw_node->bandwidth_up % 10,
+		   ntohl(gateway->bandwidth_down) / 10,
+		   ntohl(gateway->bandwidth_down) % 10,
+		   ntohl(gateway->bandwidth_up) / 10,
+		   ntohl(gateway->bandwidth_up) % 10);
+
+	gw_node->bandwidth_down = ntohl(gateway->bandwidth_down);
+	gw_node->bandwidth_up = ntohl(gateway->bandwidth_up);
+
+	gw_node->deleted = 0;
+	if (ntohl(gateway->bandwidth_down) == 0) {
+		gw_node->deleted = jiffies;
+		batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
+			   "Gateway %pM removed from gateway list\n",
+			   orig_node->orig);
+
+		/* Note: We don't need a NULL check here, since curr_gw never
+		 * gets dereferenced.
+		 */
+		curr_gw = batadv_gw_get_selected_gw_node(bat_priv);
+		if (gw_node == curr_gw)
+			batadv_gw_reselect(bat_priv);
+	}
+
+out:
+	if (curr_gw)
+		batadv_gw_node_free_ref(curr_gw);
+	if (gw_node)
+		batadv_gw_node_free_ref(gw_node);
+}
+
+void batadv_gw_node_delete(struct batadv_priv *bat_priv,
+			   struct batadv_orig_node *orig_node)
+{
+	struct batadv_tvlv_gateway_data gateway;
+
+	gateway.bandwidth_down = 0;
+	gateway.bandwidth_up = 0;
+
+	batadv_gw_node_update(bat_priv, orig_node, &gateway);
+}
+
+void batadv_gw_node_purge(struct batadv_priv *bat_priv)
+{
+	struct batadv_gw_node *gw_node, *curr_gw;
+	struct hlist_node *node_tmp;
+	unsigned long timeout = msecs_to_jiffies(2 * BATADV_PURGE_TIMEOUT);
+	int do_reselect = 0;
+
+	curr_gw = batadv_gw_get_selected_gw_node(bat_priv);
+
+	spin_lock_bh(&bat_priv->gw.list_lock);
+
+	hlist_for_each_entry_safe(gw_node, node_tmp,
+				  &bat_priv->gw.list, list) {
+		if (((!gw_node->deleted) ||
+		     (time_before(jiffies, gw_node->deleted + timeout))) &&
+		    atomic_read(&bat_priv->mesh_state) == BATADV_MESH_ACTIVE)
+			continue;
+
+		if (curr_gw == gw_node)
+			do_reselect = 1;
+
+		hlist_del_rcu(&gw_node->list);
+		batadv_gw_node_free_ref(gw_node);
+	}
+
+	spin_unlock_bh(&bat_priv->gw.list_lock);
+
+	/* gw_reselect() needs to acquire the gw_list_lock */
+	if (do_reselect)
+		batadv_gw_reselect(bat_priv);
+
+	if (curr_gw)
+		batadv_gw_node_free_ref(curr_gw);
+}
+
+/* fails if orig_node has no router */
+static int batadv_write_buffer_text(struct batadv_priv *bat_priv,
+				    struct seq_file *seq,
+				    const struct batadv_gw_node *gw_node)
+{
+	struct batadv_gw_node *curr_gw;
+	struct batadv_neigh_node *router;
+	struct batadv_neigh_ifinfo *router_ifinfo = NULL;
+	int ret = -1;
+
+	router = batadv_orig_router_get(gw_node->orig_node, BATADV_IF_DEFAULT);
+	if (!router)
+		goto out;
+
+	router_ifinfo = batadv_neigh_ifinfo_get(router, BATADV_IF_DEFAULT);
+	if (!router_ifinfo)
+		goto out;
+
+	curr_gw = batadv_gw_get_selected_gw_node(bat_priv);
+
+	seq_printf(seq, "%s %pM (%3i) %pM [%10s]: %u.%u/%u.%u MBit\n",
+		   (curr_gw == gw_node ? "=>" : "  "),
+		   gw_node->orig_node->orig,
+		   router_ifinfo->bat_iv.tq_avg, router->addr,
+		   router->if_incoming->net_dev->name,
+		   gw_node->bandwidth_down / 10,
+		   gw_node->bandwidth_down % 10,
+		   gw_node->bandwidth_up / 10,
+		   gw_node->bandwidth_up % 10);
+	ret = seq_has_overflowed(seq) ? -1 : 0;
+
+	if (curr_gw)
+		batadv_gw_node_free_ref(curr_gw);
+out:
+	if (router_ifinfo)
+		batadv_neigh_ifinfo_free_ref(router_ifinfo);
+	if (router)
+		batadv_neigh_node_free_ref(router);
+	return ret;
+}
+
+int batadv_gw_client_seq_print_text(struct seq_file *seq, void *offset)
+{
+	struct net_device *net_dev = (struct net_device *)seq->private;
+	struct batadv_priv *bat_priv = netdev_priv(net_dev);
+	struct batadv_hard_iface *primary_if;
+	struct batadv_gw_node *gw_node;
+	int gw_count = 0;
+
+	primary_if = batadv_seq_print_text_primary_if_get(seq);
+	if (!primary_if)
+		goto out;
+
+	seq_printf(seq,
+		   "      %-12s (%s/%i) %17s [%10s]: advertised uplink bandwidth ... [B.A.T.M.A.N. adv %s, MainIF/MAC: %s/%pM (%s)]\n",
+		   "Gateway", "#", BATADV_TQ_MAX_VALUE, "Nexthop", "outgoingIF",
+		   BATADV_SOURCE_VERSION, primary_if->net_dev->name,
+		   primary_if->net_dev->dev_addr, net_dev->name);
+
+	rcu_read_lock();
+	hlist_for_each_entry_rcu(gw_node, &bat_priv->gw.list, list) {
+		if (gw_node->deleted)
+			continue;
+
+		/* fails if orig_node has no router */
+		if (batadv_write_buffer_text(bat_priv, seq, gw_node) < 0)
+			continue;
+
+		gw_count++;
+	}
+	rcu_read_unlock();
+
+	if (gw_count == 0)
+		seq_puts(seq, "No gateways in range ...\n");
+
+out:
+	if (primary_if)
+		batadv_hardif_free_ref(primary_if);
+	return 0;
+}
+
+/**
+ * batadv_gw_dhcp_recipient_get - check if a packet is a DHCP message
+ * @skb: the packet to check
+ * @header_len: a pointer to the batman-adv header size
+ * @chaddr: buffer where the client address will be stored. Valid
+ *  only if the function returns BATADV_DHCP_TO_CLIENT
+ *
+ * Returns:
+ * - BATADV_DHCP_NO if the packet is not a dhcp message or if there was an error
+ *   while parsing it
+ * - BATADV_DHCP_TO_SERVER if this is a message going to the DHCP server
+ * - BATADV_DHCP_TO_CLIENT if this is a message going to a DHCP client
+ *
+ * This function may re-allocate the data buffer of the skb passed as argument.
+ */
+enum batadv_dhcp_recipient
+batadv_gw_dhcp_recipient_get(struct sk_buff *skb, unsigned int *header_len,
+			     uint8_t *chaddr)
+{
+	enum batadv_dhcp_recipient ret = BATADV_DHCP_NO;
+	struct ethhdr *ethhdr;
+	struct iphdr *iphdr;
+	struct ipv6hdr *ipv6hdr;
+	struct udphdr *udphdr;
+	struct vlan_ethhdr *vhdr;
+	int chaddr_offset;
+	__be16 proto;
+	uint8_t *p;
+
+	/* check for ethernet header */
+	if (!pskb_may_pull(skb, *header_len + ETH_HLEN))
+		return BATADV_DHCP_NO;
+
+	ethhdr = eth_hdr(skb);
+	proto = ethhdr->h_proto;
+	*header_len += ETH_HLEN;
+
+	/* check for initial vlan header */
+	if (proto == htons(ETH_P_8021Q)) {
+		if (!pskb_may_pull(skb, *header_len + VLAN_HLEN))
+			return BATADV_DHCP_NO;
+
+		vhdr = vlan_eth_hdr(skb);
+		proto = vhdr->h_vlan_encapsulated_proto;
+		*header_len += VLAN_HLEN;
+	}
+
+	/* check for ip header */
+	switch (proto) {
+	case htons(ETH_P_IP):
+		if (!pskb_may_pull(skb, *header_len + sizeof(*iphdr)))
+			return BATADV_DHCP_NO;
+
+		iphdr = (struct iphdr *)(skb->data + *header_len);
+		*header_len += iphdr->ihl * 4;
+
+		/* check for udp header */
+		if (iphdr->protocol != IPPROTO_UDP)
+			return BATADV_DHCP_NO;
+
+		break;
+	case htons(ETH_P_IPV6):
+		if (!pskb_may_pull(skb, *header_len + sizeof(*ipv6hdr)))
+			return BATADV_DHCP_NO;
+
+		ipv6hdr = (struct ipv6hdr *)(skb->data + *header_len);
+		*header_len += sizeof(*ipv6hdr);
+
+		/* check for udp header */
+		if (ipv6hdr->nexthdr != IPPROTO_UDP)
+			return BATADV_DHCP_NO;
+
+		break;
+	default:
+		return BATADV_DHCP_NO;
+	}
+
+	if (!pskb_may_pull(skb, *header_len + sizeof(*udphdr)))
+		return BATADV_DHCP_NO;
+
+	/* skb->data might have been reallocated by pskb_may_pull() */
+	ethhdr = eth_hdr(skb);
+	if (ntohs(ethhdr->h_proto) == ETH_P_8021Q)
+		ethhdr = (struct ethhdr *)(skb->data + VLAN_HLEN);
+
+	udphdr = (struct udphdr *)(skb->data + *header_len);
+	*header_len += sizeof(*udphdr);
+
+	/* check for bootp port */
+	switch (proto) {
+	case htons(ETH_P_IP):
+		if (udphdr->dest == htons(67))
+			ret = BATADV_DHCP_TO_SERVER;
+		else if (udphdr->source == htons(67))
+			ret = BATADV_DHCP_TO_CLIENT;
+		break;
+	case htons(ETH_P_IPV6):
+		if (udphdr->dest == htons(547))
+			ret = BATADV_DHCP_TO_SERVER;
+		else if (udphdr->source == htons(547))
+			ret = BATADV_DHCP_TO_CLIENT;
+		break;
+	}
+
+	chaddr_offset = *header_len + BATADV_DHCP_CHADDR_OFFSET;
+	/* store the client address if the message is going to a client */
+	if (ret == BATADV_DHCP_TO_CLIENT &&
+	    pskb_may_pull(skb, chaddr_offset + ETH_ALEN)) {
+		/* check if the DHCP packet carries an Ethernet DHCP */
+		p = skb->data + *header_len + BATADV_DHCP_HTYPE_OFFSET;
+		if (*p != BATADV_DHCP_HTYPE_ETHERNET)
+			return BATADV_DHCP_NO;
+
+		/* check if the DHCP packet carries a valid Ethernet address */
+		p = skb->data + *header_len + BATADV_DHCP_HLEN_OFFSET;
+		if (*p != ETH_ALEN)
+			return BATADV_DHCP_NO;
+
+		ether_addr_copy(chaddr, skb->data + chaddr_offset);
+	}
+
+	return ret;
+}
+
+/**
+ * batadv_gw_out_of_range - check if the dhcp request destination is the best gw
+ * @bat_priv: the bat priv with all the soft interface information
+ * @skb: the outgoing packet
+ *
+ * Check if the skb is a DHCP request and if it is sent to the current best GW
+ * server. Due to topology changes it may be the case that the GW server
+ * previously selected is not the best one anymore.
+ *
+ * Returns true if the packet destination is unicast and it is not the best gw,
+ * false otherwise.
+ *
+ * This call might reallocate skb data.
+ * Must be invoked only when the DHCP packet is going TO a DHCP SERVER.
+ */
+bool batadv_gw_out_of_range(struct batadv_priv *bat_priv,
+			    struct sk_buff *skb)
+{
+	struct batadv_neigh_node *neigh_curr = NULL, *neigh_old = NULL;
+	struct batadv_orig_node *orig_dst_node = NULL;
+	struct batadv_gw_node *gw_node = NULL, *curr_gw = NULL;
+	struct batadv_neigh_ifinfo *curr_ifinfo, *old_ifinfo;
+	struct ethhdr *ethhdr = (struct ethhdr *)skb->data;
+	bool out_of_range = false;
+	uint8_t curr_tq_avg;
+	unsigned short vid;
+
+	vid = batadv_get_vid(skb, 0);
+
+	orig_dst_node = batadv_transtable_search(bat_priv, ethhdr->h_source,
+						 ethhdr->h_dest, vid);
+	if (!orig_dst_node)
+		goto out;
+
+	gw_node = batadv_gw_node_get(bat_priv, orig_dst_node);
+	if (!gw_node)
+		goto out;
+
+	switch (atomic_read(&bat_priv->gw_mode)) {
+	case BATADV_GW_MODE_SERVER:
+		/* If we are a GW then we are our best GW. We can artificially
+		 * set the tq towards ourself as the maximum value
+		 */
+		curr_tq_avg = BATADV_TQ_MAX_VALUE;
+		break;
+	case BATADV_GW_MODE_CLIENT:
+		curr_gw = batadv_gw_get_selected_gw_node(bat_priv);
+		if (!curr_gw)
+			goto out;
+
+		/* packet is going to our gateway */
+		if (curr_gw->orig_node == orig_dst_node)
+			goto out;
+
+		/* If the dhcp packet has been sent to a different gw,
+		 * we have to evaluate whether the old gw is still
+		 * reliable enough
+		 */
+		neigh_curr = batadv_find_router(bat_priv, curr_gw->orig_node,
+						NULL);
+		if (!neigh_curr)
+			goto out;
+
+		curr_ifinfo = batadv_neigh_ifinfo_get(neigh_curr,
+						      BATADV_IF_DEFAULT);
+		if (!curr_ifinfo)
+			goto out;
+
+		curr_tq_avg = curr_ifinfo->bat_iv.tq_avg;
+		batadv_neigh_ifinfo_free_ref(curr_ifinfo);
+
+		break;
+	case BATADV_GW_MODE_OFF:
+	default:
+		goto out;
+	}
+
+	neigh_old = batadv_find_router(bat_priv, orig_dst_node, NULL);
+	if (!neigh_old)
+		goto out;
+
+	old_ifinfo = batadv_neigh_ifinfo_get(neigh_old, BATADV_IF_DEFAULT);
+	if (!old_ifinfo)
+		goto out;
+
+	if ((curr_tq_avg - old_ifinfo->bat_iv.tq_avg) > BATADV_GW_THRESHOLD)
+		out_of_range = true;
+	batadv_neigh_ifinfo_free_ref(old_ifinfo);
+
+out:
+	if (orig_dst_node)
+		batadv_orig_node_free_ref(orig_dst_node);
+	if (curr_gw)
+		batadv_gw_node_free_ref(curr_gw);
+	if (gw_node)
+		batadv_gw_node_free_ref(gw_node);
+	if (neigh_old)
+		batadv_neigh_node_free_ref(neigh_old);
+	if (neigh_curr)
+		batadv_neigh_node_free_ref(neigh_curr);
+	return out_of_range;
+}