net/batman-adv/gateway_client.c - kernel/msm-4.9 - Gitiles

 /*
  * Copyright (C) 2009-2012 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, write to the Free Software
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
  * 02110-1301, USA
  *
  */

 #include "main.h"
 #include "bat_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>

 /* This is the offset of the options field in a dhcp packet starting at
  * the beginning of the dhcp header */
 #define DHCP_OPTIONS_OFFSET 240
 #define DHCP_REQUEST 3

 static void gw_node_free_ref(struct gw_node *gw_node)
 {
 	if (atomic_dec_and_test(&gw_node->refcount))
 		kfree_rcu(gw_node, rcu);
 }

 static struct gw_node *gw_get_selected_gw_node(struct bat_priv *bat_priv)
 {
 	struct gw_node *gw_node;

 	rcu_read_lock();
 	gw_node = rcu_dereference(bat_priv->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 orig_node *gw_get_selected_orig(struct bat_priv *bat_priv)
 {
 	struct gw_node *gw_node;
 	struct orig_node *orig_node = NULL;

 	gw_node = 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)
 		gw_node_free_ref(gw_node);
 	return orig_node;
 }

 static void gw_select(struct bat_priv *bat_priv, struct gw_node *new_gw_node)
 {
 	struct 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->curr_gw, 1);
 	rcu_assign_pointer(bat_priv->curr_gw, new_gw_node);

 	if (curr_gw_node)
 		gw_node_free_ref(curr_gw_node);

 	spin_unlock_bh(&bat_priv->gw_list_lock);
 }

 void gw_deselect(struct bat_priv *bat_priv)
 {
 	atomic_set(&bat_priv->gw_reselect, 1);
 }

 static struct gw_node *gw_get_best_gw_node(struct bat_priv *bat_priv)
 {
 	struct neigh_node *router;
 	struct hlist_node *node;
 	struct gw_node *gw_node, *curr_gw = NULL;
 	uint32_t max_gw_factor = 0, tmp_gw_factor = 0;
 	uint8_t max_tq = 0;
 	int down, up;

 	rcu_read_lock();
 	hlist_for_each_entry_rcu(gw_node, node, &bat_priv->gw_list, list) {
 		if (gw_node->deleted)
 			continue;

 		router = orig_node_get_router(gw_node->orig_node);
 		if (!router)
 			continue;

 		if (!atomic_inc_not_zero(&gw_node->refcount))
 			goto next;

 		switch (atomic_read(&bat_priv->gw_sel_class)) {
 		case 1: /* fast connection */
 			gw_bandwidth_to_kbit(gw_node->orig_node->gw_flags,
 					     &down, &up);

 			tmp_gw_factor = (router->tq_avg * router->tq_avg *
 					 down * 100 * 100) /
 					 (TQ_LOCAL_WINDOW_SIZE *
 					 TQ_LOCAL_WINDOW_SIZE * 64);

 			if ((tmp_gw_factor > max_gw_factor) ||
 			    ((tmp_gw_factor == max_gw_factor) &&
 			     (router->tq_avg > max_tq))) {
 				if (curr_gw)
 					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 (router->tq_avg > max_tq) {
 				if (curr_gw)
 					gw_node_free_ref(curr_gw);
 				curr_gw = gw_node;
 				atomic_inc(&curr_gw->refcount);
 			}
 			break;
 		}

 		if (router->tq_avg > max_tq)
 			max_tq = router->tq_avg;

 		if (tmp_gw_factor > max_gw_factor)
 			max_gw_factor = tmp_gw_factor;

 		gw_node_free_ref(gw_node);

 next:
 		neigh_node_free_ref(router);
 	}
 	rcu_read_unlock();

 	return curr_gw;
 }

 void gw_election(struct bat_priv *bat_priv)
 {
 	struct gw_node *curr_gw = NULL, *next_gw = NULL;
 	struct neigh_node *router = NULL;
 	char gw_addr[18] = { '\0' };

 	/**
 	 * The batman daemon checks here if we already passed a full originator
 	 * cycle in order to make sure we don't choose the first gateway we
 	 * hear about. This check is based on the daemon's uptime which we
 	 * don't have.
 	 **/
 	if (atomic_read(&bat_priv->gw_mode) != GW_MODE_CLIENT)
 		goto out;

 	if (!atomic_dec_not_zero(&bat_priv->gw_reselect))
 		goto out;

 	curr_gw = gw_get_selected_gw_node(bat_priv);

 	next_gw = 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 = orig_node_get_router(next_gw->orig_node);
 		if (!router) {
 			gw_deselect(bat_priv);
 			goto out;
 		}
 	}

 	if ((curr_gw) && (!next_gw)) {
 		bat_dbg(DBG_BATMAN, bat_priv,
 			"Removing selected gateway - no gateway in range\n");
 		throw_uevent(bat_priv, UEV_GW, UEV_DEL, NULL);
 	} else if ((!curr_gw) && (next_gw)) {
 		bat_dbg(DBG_BATMAN, bat_priv,
 			"Adding route to gateway %pM (gw_flags: %i, tq: %i)\n",
 			next_gw->orig_node->orig, next_gw->orig_node->gw_flags,
 			router->tq_avg);
 		throw_uevent(bat_priv, UEV_GW, UEV_ADD, gw_addr);
 	} else {
 		bat_dbg(DBG_BATMAN, bat_priv,
 			"Changing route to gateway %pM (gw_flags: %i, tq: %i)\n",
 			next_gw->orig_node->orig, next_gw->orig_node->gw_flags,
 			router->tq_avg);
 		throw_uevent(bat_priv, UEV_GW, UEV_CHANGE, gw_addr);
 	}

 	gw_select(bat_priv, next_gw);

 out:
 	if (curr_gw)
 		gw_node_free_ref(curr_gw);
 	if (next_gw)
 		gw_node_free_ref(next_gw);
 	if (router)
 		neigh_node_free_ref(router);
 }

 void gw_check_election(struct bat_priv *bat_priv, struct orig_node *orig_node)
 {
 	struct orig_node *curr_gw_orig;
 	struct neigh_node *router_gw = NULL, *router_orig = NULL;
 	uint8_t gw_tq_avg, orig_tq_avg;

 	curr_gw_orig = gw_get_selected_orig(bat_priv);
 	if (!curr_gw_orig)
 		goto deselect;

 	router_gw = orig_node_get_router(curr_gw_orig);
 	if (!router_gw)
 		goto deselect;

 	/* this node already is the gateway */
 	if (curr_gw_orig == orig_node)
 		goto out;

 	router_orig = orig_node_get_router(orig_node);
 	if (!router_orig)
 		goto out;

 	gw_tq_avg = router_gw->tq_avg;
 	orig_tq_avg = router_orig->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;

 	bat_dbg(DBG_BATMAN, bat_priv,
 		"Restarting gateway selection: better gateway found (tq curr: %i, tq new: %i)\n",
 		gw_tq_avg, orig_tq_avg);

 deselect:
 	gw_deselect(bat_priv);
 out:
 	if (curr_gw_orig)
 		orig_node_free_ref(curr_gw_orig);
 	if (router_gw)
 		neigh_node_free_ref(router_gw);
 	if (router_orig)
 		neigh_node_free_ref(router_orig);

 	return;
 }

 static void gw_node_add(struct bat_priv *bat_priv,
 			struct orig_node *orig_node, uint8_t new_gwflags)
 {
 	struct gw_node *gw_node;
 	int down, up;

 	gw_node = kzalloc(sizeof(*gw_node), GFP_ATOMIC);
 	if (!gw_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);

 	gw_bandwidth_to_kbit(new_gwflags, &down, &up);
 	bat_dbg(DBG_BATMAN, bat_priv,
 		"Found new gateway %pM -> gw_class: %i - %i%s/%i%s\n",
 		orig_node->orig, new_gwflags,
 		(down > 2048 ? down / 1024 : down),
 		(down > 2048 ? "MBit" : "KBit"),
 		(up > 2048 ? up / 1024 : up),
 		(up > 2048 ? "MBit" : "KBit"));
 }

 void gw_node_update(struct bat_priv *bat_priv,
 		    struct orig_node *orig_node, uint8_t new_gwflags)
 {
 	struct hlist_node *node;
 	struct gw_node *gw_node, *curr_gw;

 	/**
 	 * Note: We don't need a NULL check here, since curr_gw never gets
 	 * dereferenced. If curr_gw is NULL we also should not exit as we may
 	 * have this gateway in our list (duplication check!) even though we
 	 * have no currently selected gateway.
 	 */
 	curr_gw = gw_get_selected_gw_node(bat_priv);

 	rcu_read_lock();
 	hlist_for_each_entry_rcu(gw_node, node, &bat_priv->gw_list, list) {
 		if (gw_node->orig_node != orig_node)
 			continue;

 		bat_dbg(DBG_BATMAN, bat_priv,
 			"Gateway class of originator %pM changed from %i to %i\n",
 			orig_node->orig, gw_node->orig_node->gw_flags,
 			new_gwflags);

 		gw_node->deleted = 0;

 		if (new_gwflags == NO_FLAGS) {
 			gw_node->deleted = jiffies;
 			bat_dbg(DBG_BATMAN, bat_priv,
 				"Gateway %pM removed from gateway list\n",
 				orig_node->orig);

 			if (gw_node == curr_gw)
 				goto deselect;
 		}

 		goto unlock;
 	}

 	if (new_gwflags == NO_FLAGS)
 		goto unlock;

 	gw_node_add(bat_priv, orig_node, new_gwflags);
 	goto unlock;

 deselect:
 	gw_deselect(bat_priv);
 unlock:
 	rcu_read_unlock();

 	if (curr_gw)
 		gw_node_free_ref(curr_gw);
 }

 void gw_node_delete(struct bat_priv *bat_priv, struct orig_node *orig_node)
 {
 	gw_node_update(bat_priv, orig_node, 0);
 }

 void gw_node_purge(struct bat_priv *bat_priv)
 {
 	struct gw_node *gw_node, *curr_gw;
 	struct hlist_node *node, *node_tmp;
 	unsigned long timeout = msecs_to_jiffies(2 * PURGE_TIMEOUT);
 	int do_deselect = 0;

 	curr_gw = gw_get_selected_gw_node(bat_priv);

 	spin_lock_bh(&bat_priv->gw_list_lock);

 	hlist_for_each_entry_safe(gw_node, 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) == MESH_ACTIVE)
 			continue;

 		if (curr_gw == gw_node)
 			do_deselect = 1;

 		hlist_del_rcu(&gw_node->list);
 		gw_node_free_ref(gw_node);
 	}

 	spin_unlock_bh(&bat_priv->gw_list_lock);

 	/* gw_deselect() needs to acquire the gw_list_lock */
 	if (do_deselect)
 		gw_deselect(bat_priv);

 	if (curr_gw)
 		gw_node_free_ref(curr_gw);
 }

 /**
  * fails if orig_node has no router
  */
 static int _write_buffer_text(struct bat_priv *bat_priv, struct seq_file *seq,
 			      const struct gw_node *gw_node)
 {
 	struct gw_node *curr_gw;
 	struct neigh_node *router;
 	int down, up, ret = -1;

 	gw_bandwidth_to_kbit(gw_node->orig_node->gw_flags, &down, &up);

 	router = orig_node_get_router(gw_node->orig_node);
 	if (!router)
 		goto out;

 	curr_gw = gw_get_selected_gw_node(bat_priv);

 	ret = seq_printf(seq, "%s %pM (%3i) %pM [%10s]: %3i - %i%s/%i%s\n",
 			 (curr_gw == gw_node ? "=>" : "  "),
 			 gw_node->orig_node->orig,
 			 router->tq_avg, router->addr,
 			 router->if_incoming->net_dev->name,
 			 gw_node->orig_node->gw_flags,
 			 (down > 2048 ? down / 1024 : down),
 			 (down > 2048 ? "MBit" : "KBit"),
 			 (up > 2048 ? up / 1024 : up),
 			 (up > 2048 ? "MBit" : "KBit"));

 	neigh_node_free_ref(router);
 	if (curr_gw)
 		gw_node_free_ref(curr_gw);
 out:
 	return ret;
 }

 int gw_client_seq_print_text(struct seq_file *seq, void *offset)
 {
 	struct net_device *net_dev = (struct net_device *)seq->private;
 	struct bat_priv *bat_priv = netdev_priv(net_dev);
 	struct hard_iface *primary_if;
 	struct gw_node *gw_node;
 	struct hlist_node *node;
 	int gw_count = 0, ret = 0;

 	primary_if = primary_if_get_selected(bat_priv);
 	if (!primary_if) {
 		ret = seq_printf(seq,
 				 "BATMAN mesh %s disabled - please specify interfaces to enable it\n",
 				 net_dev->name);
 		goto out;
 	}

 	if (primary_if->if_status != IF_ACTIVE) {
 		ret = seq_printf(seq,
 				 "BATMAN mesh %s disabled - primary interface not active\n",
 				 net_dev->name);
 		goto out;
 	}

 	seq_printf(seq,
 		   "      %-12s (%s/%i) %17s [%10s]: gw_class ... [B.A.T.M.A.N. adv %s, MainIF/MAC: %s/%pM (%s)]\n",
 		   "Gateway", "#", TQ_MAX_VALUE, "Nexthop", "outgoingIF",
 		   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, node, &bat_priv->gw_list, list) {
 		if (gw_node->deleted)
 			continue;

 		/* fails if orig_node has no router */
 		if (_write_buffer_text(bat_priv, seq, gw_node) < 0)
 			continue;

 		gw_count++;
 	}
 	rcu_read_unlock();

 	if (gw_count == 0)
 		seq_printf(seq, "No gateways in range ...\n");

 out:
 	if (primary_if)
 		hardif_free_ref(primary_if);
 	return ret;
 }

 static bool is_type_dhcprequest(struct sk_buff *skb, int header_len)
 {
 	int ret = false;
 	unsigned char *p;
 	int pkt_len;

 	if (skb_linearize(skb) < 0)
 		goto out;

 	pkt_len = skb_headlen(skb);

 	if (pkt_len < header_len + DHCP_OPTIONS_OFFSET + 1)
 		goto out;

 	p = skb->data + header_len + DHCP_OPTIONS_OFFSET;
 	pkt_len -= header_len + DHCP_OPTIONS_OFFSET + 1;

 	/* Access the dhcp option lists. Each entry is made up by:
 	 * - octet 1: option type
 	 * - octet 2: option data len (only if type != 255 and 0)
 	 * - octet 3: option data */
 	while (*p != 255 && !ret) {
 		/* p now points to the first octet: option type */
 		if (*p == 53) {
 			/* type 53 is the message type option.
 			 * Jump the len octet and go to the data octet */
 			if (pkt_len < 2)
 				goto out;
 			p += 2;

 			/* check if the message type is what we need */
 			if (*p == DHCP_REQUEST)
 				ret = true;
 			break;
 		} else if (*p == 0) {
 			/* option type 0 (padding), just go forward */
 			if (pkt_len < 1)
 				goto out;
 			pkt_len--;
 			p++;
 		} else {
 			/* This is any other option. So we get the length... */
 			if (pkt_len < 1)
 				goto out;
 			pkt_len--;
 			p++;

 			/* ...and then we jump over the data */
 			if (pkt_len < *p)
 				goto out;
 			pkt_len -= *p;
 			p += (*p);
 		}
 	}
 out:
 	return ret;
 }

 bool gw_is_dhcp_target(struct sk_buff *skb, unsigned int *header_len)
 {
 	struct ethhdr *ethhdr;
 	struct iphdr *iphdr;
 	struct ipv6hdr *ipv6hdr;
 	struct udphdr *udphdr;

 	/* check for ethernet header */
 	if (!pskb_may_pull(skb, *header_len + ETH_HLEN))
 		return false;
 	ethhdr = (struct ethhdr *)skb->data;
 	*header_len += ETH_HLEN;

 	/* check for initial vlan header */
 	if (ntohs(ethhdr->h_proto) == ETH_P_8021Q) {
 		if (!pskb_may_pull(skb, *header_len + VLAN_HLEN))
 			return false;
 		ethhdr = (struct ethhdr *)(skb->data + VLAN_HLEN);
 		*header_len += VLAN_HLEN;
 	}

 	/* check for ip header */
 	switch (ntohs(ethhdr->h_proto)) {
 	case ETH_P_IP:
 		if (!pskb_may_pull(skb, *header_len + sizeof(*iphdr)))
 			return false;
 		iphdr = (struct iphdr *)(skb->data + *header_len);
 		*header_len += iphdr->ihl * 4;

 		/* check for udp header */
 		if (iphdr->protocol != IPPROTO_UDP)
 			return false;

 		break;
 	case ETH_P_IPV6:
 		if (!pskb_may_pull(skb, *header_len + sizeof(*ipv6hdr)))
 			return false;
 		ipv6hdr = (struct ipv6hdr *)(skb->data + *header_len);
 		*header_len += sizeof(*ipv6hdr);

 		/* check for udp header */
 		if (ipv6hdr->nexthdr != IPPROTO_UDP)
 			return false;

 		break;
 	default:
 		return false;
 	}

 	if (!pskb_may_pull(skb, *header_len + sizeof(*udphdr)))
 		return false;
 	udphdr = (struct udphdr *)(skb->data + *header_len);
 	*header_len += sizeof(*udphdr);

 	/* check for bootp port */
 	if ((ntohs(ethhdr->h_proto) == ETH_P_IP) &&
 	    (ntohs(udphdr->dest) != 67))
 		return false;

 	if ((ntohs(ethhdr->h_proto) == ETH_P_IPV6) &&
 	    (ntohs(udphdr->dest) != 547))
 		return false;

 	return true;
 }

 bool gw_out_of_range(struct bat_priv *bat_priv,
 		     struct sk_buff *skb, struct ethhdr *ethhdr)
 {
 	struct neigh_node *neigh_curr = NULL, *neigh_old = NULL;
 	struct orig_node *orig_dst_node = NULL;
 	struct gw_node *curr_gw = NULL;
 	bool ret, out_of_range = false;
 	unsigned int header_len = 0;
 	uint8_t curr_tq_avg;

 	ret = gw_is_dhcp_target(skb, &header_len);
 	if (!ret)
 		goto out;

 	orig_dst_node = transtable_search(bat_priv, ethhdr->h_source,
 					  ethhdr->h_dest);
 	if (!orig_dst_node)
 		goto out;

 	if (!orig_dst_node->gw_flags)
 		goto out;

 	ret = is_type_dhcprequest(skb, header_len);
 	if (!ret)
 		goto out;

 	switch (atomic_read(&bat_priv->gw_mode)) {
 	case 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 = TQ_MAX_VALUE;
 		break;
 	case GW_MODE_CLIENT:
 		curr_gw = 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 = find_router(bat_priv, curr_gw->orig_node, NULL);
 		if (!neigh_curr)
 			goto out;

 		curr_tq_avg = neigh_curr->tq_avg;
 		break;
 	case GW_MODE_OFF:
 	default:
 		goto out;
 	}

 	neigh_old = find_router(bat_priv, orig_dst_node, NULL);
 	if (!neigh_old)
 		goto out;

 	if (curr_tq_avg - neigh_old->tq_avg > GW_THRESHOLD)
 		out_of_range = true;

 out:
 	if (orig_dst_node)
 		orig_node_free_ref(orig_dst_node);
 	if (curr_gw)
 		gw_node_free_ref(curr_gw);
 	if (neigh_old)
 		neigh_node_free_ref(neigh_old);
 	if (neigh_curr)
 		neigh_node_free_ref(neigh_curr);
 	return out_of_range;
 }
	/*
	* Copyright (C) 2009-2012 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, write to the Free Software
	* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
	* 02110-1301, USA
	*
	*/

	#include "main.h"
	#include "bat_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>

	/* This is the offset of the options field in a dhcp packet starting at
	* the beginning of the dhcp header */
	#define DHCP_OPTIONS_OFFSET 240
	#define DHCP_REQUEST 3

	static void gw_node_free_ref(struct gw_node *gw_node)
	{
	if (atomic_dec_and_test(&gw_node->refcount))
	kfree_rcu(gw_node, rcu);
	}

	static struct gw_node gw_get_selected_gw_node(struct bat_priv bat_priv)
	{
	struct gw_node *gw_node;

	rcu_read_lock();
	gw_node = rcu_dereference(bat_priv->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 orig_node gw_get_selected_orig(struct bat_priv bat_priv)
	{
	struct gw_node *gw_node;
	struct orig_node *orig_node = NULL;

	gw_node = 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)
	gw_node_free_ref(gw_node);
	return orig_node;
	}

	static void gw_select(struct bat_priv bat_priv, struct gw_node new_gw_node)
	{
	struct 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->curr_gw, 1);
	rcu_assign_pointer(bat_priv->curr_gw, new_gw_node);

	if (curr_gw_node)
	gw_node_free_ref(curr_gw_node);

	spin_unlock_bh(&bat_priv->gw_list_lock);
	}

	void gw_deselect(struct bat_priv *bat_priv)
	{
	atomic_set(&bat_priv->gw_reselect, 1);
	}

	static struct gw_node gw_get_best_gw_node(struct bat_priv bat_priv)
	{
	struct neigh_node *router;
	struct hlist_node *node;
	struct gw_node gw_node, curr_gw = NULL;
	uint32_t max_gw_factor = 0, tmp_gw_factor = 0;
	uint8_t max_tq = 0;
	int down, up;

	rcu_read_lock();
	hlist_for_each_entry_rcu(gw_node, node, &bat_priv->gw_list, list) {
	if (gw_node->deleted)
	continue;

	router = orig_node_get_router(gw_node->orig_node);
	if (!router)
	continue;

	if (!atomic_inc_not_zero(&gw_node->refcount))
	goto next;

	switch (atomic_read(&bat_priv->gw_sel_class)) {
	case 1: /* fast connection */
	gw_bandwidth_to_kbit(gw_node->orig_node->gw_flags,
	&down, &up);

	tmp_gw_factor = (router->tq_avg * router->tq_avg *
	down * 100 * 100) /
	(TQ_LOCAL_WINDOW_SIZE *
	TQ_LOCAL_WINDOW_SIZE * 64);

	if ((tmp_gw_factor > max_gw_factor) \|\|
	((tmp_gw_factor == max_gw_factor) &&
	(router->tq_avg > max_tq))) {
	if (curr_gw)
	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 (router->tq_avg > max_tq) {
	if (curr_gw)
	gw_node_free_ref(curr_gw);
	curr_gw = gw_node;
	atomic_inc(&curr_gw->refcount);
	}
	break;
	}

	if (router->tq_avg > max_tq)
	max_tq = router->tq_avg;

	if (tmp_gw_factor > max_gw_factor)
	max_gw_factor = tmp_gw_factor;

	gw_node_free_ref(gw_node);

	next:
	neigh_node_free_ref(router);
	}
	rcu_read_unlock();

	return curr_gw;
	}

	void gw_election(struct bat_priv *bat_priv)
	{
	struct gw_node curr_gw = NULL, next_gw = NULL;
	struct neigh_node *router = NULL;
	char gw_addr[18] = { '\0' };

	/**
	* The batman daemon checks here if we already passed a full originator
	* cycle in order to make sure we don't choose the first gateway we
	* hear about. This check is based on the daemon's uptime which we
	* don't have.
	**/
	if (atomic_read(&bat_priv->gw_mode) != GW_MODE_CLIENT)
	goto out;

	if (!atomic_dec_not_zero(&bat_priv->gw_reselect))
	goto out;

	curr_gw = gw_get_selected_gw_node(bat_priv);

	next_gw = 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 = orig_node_get_router(next_gw->orig_node);
	if (!router) {
	gw_deselect(bat_priv);
	goto out;
	}
	}

	if ((curr_gw) && (!next_gw)) {
	bat_dbg(DBG_BATMAN, bat_priv,
	"Removing selected gateway - no gateway in range\n");
	throw_uevent(bat_priv, UEV_GW, UEV_DEL, NULL);
	} else if ((!curr_gw) && (next_gw)) {
	bat_dbg(DBG_BATMAN, bat_priv,
	"Adding route to gateway %pM (gw_flags: %i, tq: %i)\n",
	next_gw->orig_node->orig, next_gw->orig_node->gw_flags,
	router->tq_avg);
	throw_uevent(bat_priv, UEV_GW, UEV_ADD, gw_addr);
	} else {
	bat_dbg(DBG_BATMAN, bat_priv,
	"Changing route to gateway %pM (gw_flags: %i, tq: %i)\n",
	next_gw->orig_node->orig, next_gw->orig_node->gw_flags,
	router->tq_avg);
	throw_uevent(bat_priv, UEV_GW, UEV_CHANGE, gw_addr);
	}

	gw_select(bat_priv, next_gw);

	out:
	if (curr_gw)
	gw_node_free_ref(curr_gw);
	if (next_gw)
	gw_node_free_ref(next_gw);
	if (router)
	neigh_node_free_ref(router);
	}

	void gw_check_election(struct bat_priv bat_priv, struct orig_node orig_node)
	{
	struct orig_node *curr_gw_orig;
	struct neigh_node router_gw = NULL, router_orig = NULL;
	uint8_t gw_tq_avg, orig_tq_avg;

	curr_gw_orig = gw_get_selected_orig(bat_priv);
	if (!curr_gw_orig)
	goto deselect;

	router_gw = orig_node_get_router(curr_gw_orig);
	if (!router_gw)
	goto deselect;

	/* this node already is the gateway */
	if (curr_gw_orig == orig_node)
	goto out;

	router_orig = orig_node_get_router(orig_node);
	if (!router_orig)
	goto out;

	gw_tq_avg = router_gw->tq_avg;
	orig_tq_avg = router_orig->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;

	bat_dbg(DBG_BATMAN, bat_priv,
	"Restarting gateway selection: better gateway found (tq curr: %i, tq new: %i)\n",
	gw_tq_avg, orig_tq_avg);

	deselect:
	gw_deselect(bat_priv);
	out:
	if (curr_gw_orig)
	orig_node_free_ref(curr_gw_orig);
	if (router_gw)
	neigh_node_free_ref(router_gw);
	if (router_orig)
	neigh_node_free_ref(router_orig);

	return;
	}

	static void gw_node_add(struct bat_priv *bat_priv,
	struct orig_node *orig_node, uint8_t new_gwflags)
	{
	struct gw_node *gw_node;
	int down, up;

	gw_node = kzalloc(sizeof(*gw_node), GFP_ATOMIC);
	if (!gw_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);

	gw_bandwidth_to_kbit(new_gwflags, &down, &up);
	bat_dbg(DBG_BATMAN, bat_priv,
	"Found new gateway %pM -> gw_class: %i - %i%s/%i%s\n",
	orig_node->orig, new_gwflags,
	(down > 2048 ? down / 1024 : down),
	(down > 2048 ? "MBit" : "KBit"),
	(up > 2048 ? up / 1024 : up),
	(up > 2048 ? "MBit" : "KBit"));
	}

	void gw_node_update(struct bat_priv *bat_priv,
	struct orig_node *orig_node, uint8_t new_gwflags)
	{
	struct hlist_node *node;
	struct gw_node gw_node, curr_gw;

	/**
	* Note: We don't need a NULL check here, since curr_gw never gets
	* dereferenced. If curr_gw is NULL we also should not exit as we may
	* have this gateway in our list (duplication check!) even though we
	* have no currently selected gateway.
	*/
	curr_gw = gw_get_selected_gw_node(bat_priv);

	rcu_read_lock();
	hlist_for_each_entry_rcu(gw_node, node, &bat_priv->gw_list, list) {
	if (gw_node->orig_node != orig_node)
	continue;

	bat_dbg(DBG_BATMAN, bat_priv,
	"Gateway class of originator %pM changed from %i to %i\n",
	orig_node->orig, gw_node->orig_node->gw_flags,
	new_gwflags);

	gw_node->deleted = 0;

	if (new_gwflags == NO_FLAGS) {
	gw_node->deleted = jiffies;
	bat_dbg(DBG_BATMAN, bat_priv,
	"Gateway %pM removed from gateway list\n",
	orig_node->orig);

	if (gw_node == curr_gw)
	goto deselect;
	}

	goto unlock;
	}

	if (new_gwflags == NO_FLAGS)
	goto unlock;

	gw_node_add(bat_priv, orig_node, new_gwflags);
	goto unlock;

	deselect:
	gw_deselect(bat_priv);
	unlock:
	rcu_read_unlock();

	if (curr_gw)
	gw_node_free_ref(curr_gw);
	}

	void gw_node_delete(struct bat_priv bat_priv, struct orig_node orig_node)
	{
	gw_node_update(bat_priv, orig_node, 0);
	}

	void gw_node_purge(struct bat_priv *bat_priv)
	{
	struct gw_node gw_node, curr_gw;
	struct hlist_node node, node_tmp;
	unsigned long timeout = msecs_to_jiffies(2 * PURGE_TIMEOUT);
	int do_deselect = 0;

	curr_gw = gw_get_selected_gw_node(bat_priv);

	spin_lock_bh(&bat_priv->gw_list_lock);

	hlist_for_each_entry_safe(gw_node, 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) == MESH_ACTIVE)
	continue;

	if (curr_gw == gw_node)
	do_deselect = 1;

	hlist_del_rcu(&gw_node->list);
	gw_node_free_ref(gw_node);
	}

	spin_unlock_bh(&bat_priv->gw_list_lock);

	/* gw_deselect() needs to acquire the gw_list_lock */
	if (do_deselect)
	gw_deselect(bat_priv);

	if (curr_gw)
	gw_node_free_ref(curr_gw);
	}

	/**
	* fails if orig_node has no router
	*/
	static int _write_buffer_text(struct bat_priv bat_priv, struct seq_file seq,
	const struct gw_node *gw_node)
	{
	struct gw_node *curr_gw;
	struct neigh_node *router;
	int down, up, ret = -1;

	gw_bandwidth_to_kbit(gw_node->orig_node->gw_flags, &down, &up);

	router = orig_node_get_router(gw_node->orig_node);
	if (!router)
	goto out;

	curr_gw = gw_get_selected_gw_node(bat_priv);

	ret = seq_printf(seq, "%s %pM (%3i) %pM [%10s]: %3i - %i%s/%i%s\n",
	(curr_gw == gw_node ? "=>" : " "),
	gw_node->orig_node->orig,
	router->tq_avg, router->addr,
	router->if_incoming->net_dev->name,
	gw_node->orig_node->gw_flags,
	(down > 2048 ? down / 1024 : down),
	(down > 2048 ? "MBit" : "KBit"),
	(up > 2048 ? up / 1024 : up),
	(up > 2048 ? "MBit" : "KBit"));

	neigh_node_free_ref(router);
	if (curr_gw)
	gw_node_free_ref(curr_gw);
	out:
	return ret;
	}

	int gw_client_seq_print_text(struct seq_file seq, void offset)
	{
	struct net_device net_dev = (struct net_device )seq->private;
	struct bat_priv *bat_priv = netdev_priv(net_dev);
	struct hard_iface *primary_if;
	struct gw_node *gw_node;
	struct hlist_node *node;
	int gw_count = 0, ret = 0;

	primary_if = primary_if_get_selected(bat_priv);
	if (!primary_if) {
	ret = seq_printf(seq,
	"BATMAN mesh %s disabled - please specify interfaces to enable it\n",
	net_dev->name);
	goto out;
	}

	if (primary_if->if_status != IF_ACTIVE) {
	ret = seq_printf(seq,
	"BATMAN mesh %s disabled - primary interface not active\n",
	net_dev->name);
	goto out;
	}

	seq_printf(seq,
	" %-12s (%s/%i) %17s [%10s]: gw_class ... [B.A.T.M.A.N. adv %s, MainIF/MAC: %s/%pM (%s)]\n",
	"Gateway", "#", TQ_MAX_VALUE, "Nexthop", "outgoingIF",
	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, node, &bat_priv->gw_list, list) {
	if (gw_node->deleted)
	continue;

	/* fails if orig_node has no router */
	if (_write_buffer_text(bat_priv, seq, gw_node) < 0)
	continue;

	gw_count++;
	}
	rcu_read_unlock();

	if (gw_count == 0)
	seq_printf(seq, "No gateways in range ...\n");

	out:
	if (primary_if)
	hardif_free_ref(primary_if);
	return ret;
	}

	static bool is_type_dhcprequest(struct sk_buff *skb, int header_len)
	{
	int ret = false;
	unsigned char *p;
	int pkt_len;

	if (skb_linearize(skb) < 0)
	goto out;

	pkt_len = skb_headlen(skb);

	if (pkt_len < header_len + DHCP_OPTIONS_OFFSET + 1)
	goto out;

	p = skb->data + header_len + DHCP_OPTIONS_OFFSET;
	pkt_len -= header_len + DHCP_OPTIONS_OFFSET + 1;

	/* Access the dhcp option lists. Each entry is made up by:
	* - octet 1: option type
	* - octet 2: option data len (only if type != 255 and 0)
	* - octet 3: option data */
	while (*p != 255 && !ret) {
	/* p now points to the first octet: option type */
	if (*p == 53) {
	/* type 53 is the message type option.
	* Jump the len octet and go to the data octet */
	if (pkt_len < 2)
	goto out;
	p += 2;

	/* check if the message type is what we need */
	if (*p == DHCP_REQUEST)
	ret = true;
	break;
	} else if (*p == 0) {
	/* option type 0 (padding), just go forward */
	if (pkt_len < 1)
	goto out;
	pkt_len--;
	p++;
	} else {
	/* This is any other option. So we get the length... */
	if (pkt_len < 1)
	goto out;
	pkt_len--;
	p++;

	/* ...and then we jump over the data */
	if (pkt_len < *p)
	goto out;
	pkt_len -= *p;
	p += (*p);
	}
	}
	out:
	return ret;
	}

	bool gw_is_dhcp_target(struct sk_buff skb, unsigned int header_len)
	{
	struct ethhdr *ethhdr;
	struct iphdr *iphdr;
	struct ipv6hdr *ipv6hdr;
	struct udphdr *udphdr;

	/* check for ethernet header */
	if (!pskb_may_pull(skb, *header_len + ETH_HLEN))
	return false;
	ethhdr = (struct ethhdr *)skb->data;
	*header_len += ETH_HLEN;

	/* check for initial vlan header */
	if (ntohs(ethhdr->h_proto) == ETH_P_8021Q) {
	if (!pskb_may_pull(skb, *header_len + VLAN_HLEN))
	return false;
	ethhdr = (struct ethhdr *)(skb->data + VLAN_HLEN);
	*header_len += VLAN_HLEN;
	}

	/* check for ip header */
	switch (ntohs(ethhdr->h_proto)) {
	case ETH_P_IP:
	if (!pskb_may_pull(skb, header_len + sizeof(iphdr)))
	return false;
	iphdr = (struct iphdr )(skb->data + header_len);
	header_len += iphdr->ihl 4;

	/* check for udp header */
	if (iphdr->protocol != IPPROTO_UDP)
	return false;

	break;
	case ETH_P_IPV6:
	if (!pskb_may_pull(skb, header_len + sizeof(ipv6hdr)))
	return false;
	ipv6hdr = (struct ipv6hdr )(skb->data + header_len);
	header_len += sizeof(ipv6hdr);

	/* check for udp header */
	if (ipv6hdr->nexthdr != IPPROTO_UDP)
	return false;

	break;
	default:
	return false;
	}

	if (!pskb_may_pull(skb, header_len + sizeof(udphdr)))
	return false;
	udphdr = (struct udphdr )(skb->data + header_len);
	header_len += sizeof(udphdr);

	/* check for bootp port */
	if ((ntohs(ethhdr->h_proto) == ETH_P_IP) &&
	(ntohs(udphdr->dest) != 67))
	return false;

	if ((ntohs(ethhdr->h_proto) == ETH_P_IPV6) &&
	(ntohs(udphdr->dest) != 547))
	return false;

	return true;
	}

	bool gw_out_of_range(struct bat_priv *bat_priv,
	struct sk_buff skb, struct ethhdr ethhdr)
	{
	struct neigh_node neigh_curr = NULL, neigh_old = NULL;
	struct orig_node *orig_dst_node = NULL;
	struct gw_node *curr_gw = NULL;
	bool ret, out_of_range = false;
	unsigned int header_len = 0;
	uint8_t curr_tq_avg;

	ret = gw_is_dhcp_target(skb, &header_len);
	if (!ret)
	goto out;

	orig_dst_node = transtable_search(bat_priv, ethhdr->h_source,
	ethhdr->h_dest);
	if (!orig_dst_node)
	goto out;

	if (!orig_dst_node->gw_flags)
	goto out;

	ret = is_type_dhcprequest(skb, header_len);
	if (!ret)
	goto out;

	switch (atomic_read(&bat_priv->gw_mode)) {
	case 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 = TQ_MAX_VALUE;
	break;
	case GW_MODE_CLIENT:
	curr_gw = 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 = find_router(bat_priv, curr_gw->orig_node, NULL);
	if (!neigh_curr)
	goto out;

	curr_tq_avg = neigh_curr->tq_avg;
	break;
	case GW_MODE_OFF:
	default:
	goto out;
	}

	neigh_old = find_router(bat_priv, orig_dst_node, NULL);
	if (!neigh_old)
	goto out;

	if (curr_tq_avg - neigh_old->tq_avg > GW_THRESHOLD)
	out_of_range = true;

	out:
	if (orig_dst_node)
	orig_node_free_ref(orig_dst_node);
	if (curr_gw)
	gw_node_free_ref(curr_gw);
	if (neigh_old)
	neigh_node_free_ref(neigh_old);
	if (neigh_curr)
	neigh_node_free_ref(neigh_curr);
	return out_of_range;
	}