/* Copyright (C) 2013-2016 B.A.T.M.A.N. contributors:
 *
 * Linus Lüssing, 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 "bat_v.h"
#include "main.h"

#include <linux/atomic.h>
#include <linux/bug.h>
#include <linux/cache.h>
#include <linux/errno.h>
#include <linux/init.h>
#include <linux/jiffies.h>
#include <linux/kernel.h>
#include <linux/kref.h>
#include <linux/netdevice.h>
#include <linux/rculist.h>
#include <linux/rcupdate.h>
#include <linux/seq_file.h>
#include <linux/stddef.h>
#include <linux/types.h>
#include <linux/workqueue.h>

#include "bat_algo.h"
#include "bat_v_elp.h"
#include "bat_v_ogm.h"
#include "gateway_client.h"
#include "gateway_common.h"
#include "hard-interface.h"
#include "hash.h"
#include "log.h"
#include "originator.h"
#include "packet.h"

static void batadv_v_iface_activate(struct batadv_hard_iface *hard_iface)
{
	struct batadv_priv *bat_priv = netdev_priv(hard_iface->soft_iface);
	struct batadv_hard_iface *primary_if;

	primary_if = batadv_primary_if_get_selected(bat_priv);

	if (primary_if) {
		batadv_v_elp_iface_activate(primary_if, hard_iface);
		batadv_hardif_put(primary_if);
	}

	/* B.A.T.M.A.N. V does not use any queuing mechanism, therefore it can
	 * set the interface as ACTIVE right away, without any risk of race
	 * condition
	 */
	if (hard_iface->if_status == BATADV_IF_TO_BE_ACTIVATED)
		hard_iface->if_status = BATADV_IF_ACTIVE;
}

static int batadv_v_iface_enable(struct batadv_hard_iface *hard_iface)
{
	int ret;

	ret = batadv_v_elp_iface_enable(hard_iface);
	if (ret < 0)
		return ret;

	ret = batadv_v_ogm_iface_enable(hard_iface);
	if (ret < 0)
		batadv_v_elp_iface_disable(hard_iface);

	return ret;
}

static void batadv_v_iface_disable(struct batadv_hard_iface *hard_iface)
{
	batadv_v_elp_iface_disable(hard_iface);
}

static void batadv_v_primary_iface_set(struct batadv_hard_iface *hard_iface)
{
	batadv_v_elp_primary_iface_set(hard_iface);
	batadv_v_ogm_primary_iface_set(hard_iface);
}

/**
 * batadv_v_iface_update_mac - react to hard-interface MAC address change
 * @hard_iface: the modified interface
 *
 * If the modified interface is the primary one, update the originator
 * address in the ELP and OGM messages to reflect the new MAC address.
 */
static void batadv_v_iface_update_mac(struct batadv_hard_iface *hard_iface)
{
	struct batadv_priv *bat_priv = netdev_priv(hard_iface->soft_iface);
	struct batadv_hard_iface *primary_if;

	primary_if = batadv_primary_if_get_selected(bat_priv);
	if (primary_if != hard_iface)
		goto out;

	batadv_v_primary_iface_set(hard_iface);
out:
	if (primary_if)
		batadv_hardif_put(primary_if);
}

static void
batadv_v_hardif_neigh_init(struct batadv_hardif_neigh_node *hardif_neigh)
{
	ewma_throughput_init(&hardif_neigh->bat_v.throughput);
	INIT_WORK(&hardif_neigh->bat_v.metric_work,
		  batadv_v_elp_throughput_metric_update);
}

/**
 * batadv_v_orig_print_neigh - print neighbors for the originator table
 * @orig_node: the orig_node for which the neighbors are printed
 * @if_outgoing: outgoing interface for these entries
 * @seq: debugfs table seq_file struct
 *
 * Must be called while holding an rcu lock.
 */
static void
batadv_v_orig_print_neigh(struct batadv_orig_node *orig_node,
			  struct batadv_hard_iface *if_outgoing,
			  struct seq_file *seq)
{
	struct batadv_neigh_node *neigh_node;
	struct batadv_neigh_ifinfo *n_ifinfo;

	hlist_for_each_entry_rcu(neigh_node, &orig_node->neigh_list, list) {
		n_ifinfo = batadv_neigh_ifinfo_get(neigh_node, if_outgoing);
		if (!n_ifinfo)
			continue;

		seq_printf(seq, " %pM (%9u.%1u)",
			   neigh_node->addr,
			   n_ifinfo->bat_v.throughput / 10,
			   n_ifinfo->bat_v.throughput % 10);

		batadv_neigh_ifinfo_put(n_ifinfo);
	}
}

/**
 * batadv_v_hardif_neigh_print - print a single ELP neighbour node
 * @seq: neighbour table seq_file struct
 * @hardif_neigh: hardif neighbour information
 */
static void
batadv_v_hardif_neigh_print(struct seq_file *seq,
			    struct batadv_hardif_neigh_node *hardif_neigh)
{
	int last_secs, last_msecs;
	u32 throughput;

	last_secs = jiffies_to_msecs(jiffies - hardif_neigh->last_seen) / 1000;
	last_msecs = jiffies_to_msecs(jiffies - hardif_neigh->last_seen) % 1000;
	throughput = ewma_throughput_read(&hardif_neigh->bat_v.throughput);

	seq_printf(seq, "%pM %4i.%03is (%9u.%1u) [%10s]\n",
		   hardif_neigh->addr, last_secs, last_msecs, throughput / 10,
		   throughput % 10, hardif_neigh->if_incoming->net_dev->name);
}

/**
 * batadv_v_neigh_print - print the single hop neighbour list
 * @bat_priv: the bat priv with all the soft interface information
 * @seq: neighbour table seq_file struct
 */
static void batadv_v_neigh_print(struct batadv_priv *bat_priv,
				 struct seq_file *seq)
{
	struct net_device *net_dev = (struct net_device *)seq->private;
	struct batadv_hardif_neigh_node *hardif_neigh;
	struct batadv_hard_iface *hard_iface;
	int batman_count = 0;

	seq_puts(seq,
		 "  Neighbor        last-seen ( throughput) [        IF]\n");

	rcu_read_lock();
	list_for_each_entry_rcu(hard_iface, &batadv_hardif_list, list) {
		if (hard_iface->soft_iface != net_dev)
			continue;

		hlist_for_each_entry_rcu(hardif_neigh,
					 &hard_iface->neigh_list, list) {
			batadv_v_hardif_neigh_print(seq, hardif_neigh);
			batman_count++;
		}
	}
	rcu_read_unlock();

	if (batman_count == 0)
		seq_puts(seq, "No batman nodes in range ...\n");
}

/**
 * batadv_v_orig_print - print the originator table
 * @bat_priv: the bat priv with all the soft interface information
 * @seq: debugfs table seq_file struct
 * @if_outgoing: the outgoing interface for which this should be printed
 */
static void batadv_v_orig_print(struct batadv_priv *bat_priv,
				struct seq_file *seq,
				struct batadv_hard_iface *if_outgoing)
{
	struct batadv_neigh_node *neigh_node;
	struct batadv_hashtable *hash = bat_priv->orig_hash;
	int last_seen_msecs, last_seen_secs;
	struct batadv_orig_node *orig_node;
	struct batadv_neigh_ifinfo *n_ifinfo;
	unsigned long last_seen_jiffies;
	struct hlist_head *head;
	int batman_count = 0;
	u32 i;

	seq_puts(seq,
		 "  Originator      last-seen ( throughput)           Nexthop [outgoingIF]:   Potential nexthops ...\n");

	for (i = 0; i < hash->size; i++) {
		head = &hash->table[i];

		rcu_read_lock();
		hlist_for_each_entry_rcu(orig_node, head, hash_entry) {
			neigh_node = batadv_orig_router_get(orig_node,
							    if_outgoing);
			if (!neigh_node)
				continue;

			n_ifinfo = batadv_neigh_ifinfo_get(neigh_node,
							   if_outgoing);
			if (!n_ifinfo)
				goto next;

			last_seen_jiffies = jiffies - orig_node->last_seen;
			last_seen_msecs = jiffies_to_msecs(last_seen_jiffies);
			last_seen_secs = last_seen_msecs / 1000;
			last_seen_msecs = last_seen_msecs % 1000;

			seq_printf(seq, "%pM %4i.%03is (%9u.%1u) %pM [%10s]:",
				   orig_node->orig, last_seen_secs,
				   last_seen_msecs,
				   n_ifinfo->bat_v.throughput / 10,
				   n_ifinfo->bat_v.throughput % 10,
				   neigh_node->addr,
				   neigh_node->if_incoming->net_dev->name);

			batadv_v_orig_print_neigh(orig_node, if_outgoing, seq);
			seq_puts(seq, "\n");
			batman_count++;

next:
			batadv_neigh_node_put(neigh_node);
			if (n_ifinfo)
				batadv_neigh_ifinfo_put(n_ifinfo);
		}
		rcu_read_unlock();
	}

	if (batman_count == 0)
		seq_puts(seq, "No batman nodes in range ...\n");
}

static int batadv_v_neigh_cmp(struct batadv_neigh_node *neigh1,
			      struct batadv_hard_iface *if_outgoing1,
			      struct batadv_neigh_node *neigh2,
			      struct batadv_hard_iface *if_outgoing2)
{
	struct batadv_neigh_ifinfo *ifinfo1, *ifinfo2;
	int ret = 0;

	ifinfo1 = batadv_neigh_ifinfo_get(neigh1, if_outgoing1);
	if (WARN_ON(!ifinfo1))
		goto err_ifinfo1;

	ifinfo2 = batadv_neigh_ifinfo_get(neigh2, if_outgoing2);
	if (WARN_ON(!ifinfo2))
		goto err_ifinfo2;

	ret = ifinfo1->bat_v.throughput - ifinfo2->bat_v.throughput;

	batadv_neigh_ifinfo_put(ifinfo2);
err_ifinfo2:
	batadv_neigh_ifinfo_put(ifinfo1);
err_ifinfo1:
	return ret;
}

static bool batadv_v_neigh_is_sob(struct batadv_neigh_node *neigh1,
				  struct batadv_hard_iface *if_outgoing1,
				  struct batadv_neigh_node *neigh2,
				  struct batadv_hard_iface *if_outgoing2)
{
	struct batadv_neigh_ifinfo *ifinfo1, *ifinfo2;
	u32 threshold;
	bool ret = false;

	ifinfo1 = batadv_neigh_ifinfo_get(neigh1, if_outgoing1);
	if (WARN_ON(!ifinfo1))
		goto err_ifinfo1;

	ifinfo2 = batadv_neigh_ifinfo_get(neigh2, if_outgoing2);
	if (WARN_ON(!ifinfo2))
		goto err_ifinfo2;

	threshold = ifinfo1->bat_v.throughput / 4;
	threshold = ifinfo1->bat_v.throughput - threshold;

	ret = ifinfo2->bat_v.throughput > threshold;

	batadv_neigh_ifinfo_put(ifinfo2);
err_ifinfo2:
	batadv_neigh_ifinfo_put(ifinfo1);
err_ifinfo1:
	return ret;
}

static ssize_t batadv_v_store_sel_class(struct batadv_priv *bat_priv,
					char *buff, size_t count)
{
	u32 old_class, class;

	if (!batadv_parse_throughput(bat_priv->soft_iface, buff,
				     "B.A.T.M.A.N. V GW selection class",
				     &class))
		return -EINVAL;

	old_class = atomic_read(&bat_priv->gw.sel_class);
	atomic_set(&bat_priv->gw.sel_class, class);

	if (old_class != class)
		batadv_gw_reselect(bat_priv);

	return count;
}

static ssize_t batadv_v_show_sel_class(struct batadv_priv *bat_priv, char *buff)
{
	u32 class = atomic_read(&bat_priv->gw.sel_class);

	return sprintf(buff, "%u.%u MBit\n", class / 10, class % 10);
}

/**
 * batadv_v_gw_throughput_get - retrieve the GW-bandwidth for a given GW
 * @gw_node: the GW to retrieve the metric for
 * @bw: the pointer where the metric will be stored. The metric is computed as
 *  the minimum between the GW advertised throughput and the path throughput to
 *  it in the mesh
 *
 * Return: 0 on success, -1 on failure
 */
static int batadv_v_gw_throughput_get(struct batadv_gw_node *gw_node, u32 *bw)
{
	struct batadv_neigh_ifinfo *router_ifinfo = NULL;
	struct batadv_orig_node *orig_node;
	struct batadv_neigh_node *router;
	int ret = -1;

	orig_node = gw_node->orig_node;
	router = batadv_orig_router_get(orig_node, BATADV_IF_DEFAULT);
	if (!router)
		goto out;

	router_ifinfo = batadv_neigh_ifinfo_get(router, BATADV_IF_DEFAULT);
	if (!router_ifinfo)
		goto out;

	/* the GW metric is computed as the minimum between the path throughput
	 * to reach the GW itself and the advertised bandwidth.
	 * This gives us an approximation of the effective throughput that the
	 * client can expect via this particular GW node
	 */
	*bw = router_ifinfo->bat_v.throughput;
	*bw = min_t(u32, *bw, gw_node->bandwidth_down);

	ret = 0;
out:
	if (router)
		batadv_neigh_node_put(router);
	if (router_ifinfo)
		batadv_neigh_ifinfo_put(router_ifinfo);

	return ret;
}

/**
 * batadv_v_gw_get_best_gw_node - retrieve the best GW node
 * @bat_priv: the bat priv with all the soft interface information
 *
 * Return: the GW node having the best GW-metric, NULL if no GW is known
 */
static struct batadv_gw_node *
batadv_v_gw_get_best_gw_node(struct batadv_priv *bat_priv)
{
	struct batadv_gw_node *gw_node, *curr_gw = NULL;
	u32 max_bw = 0, bw;

	rcu_read_lock();
	hlist_for_each_entry_rcu(gw_node, &bat_priv->gw.list, list) {
		if (!kref_get_unless_zero(&gw_node->refcount))
			continue;

		if (batadv_v_gw_throughput_get(gw_node, &bw) < 0)
			goto next;

		if (curr_gw && (bw <= max_bw))
			goto next;

		if (curr_gw)
			batadv_gw_node_put(curr_gw);

		curr_gw = gw_node;
		kref_get(&curr_gw->refcount);
		max_bw = bw;

next:
		batadv_gw_node_put(gw_node);
	}
	rcu_read_unlock();

	return curr_gw;
}

/**
 * batadv_v_gw_is_eligible - check if a originator would be selected as GW
 * @bat_priv: the bat priv with all the soft interface information
 * @curr_gw_orig: originator representing the currently selected GW
 * @orig_node: the originator representing the new candidate
 *
 * Return: true if orig_node can be selected as current GW, false otherwise
 */
static bool batadv_v_gw_is_eligible(struct batadv_priv *bat_priv,
				    struct batadv_orig_node *curr_gw_orig,
				    struct batadv_orig_node *orig_node)
{
	struct batadv_gw_node *curr_gw = NULL, *orig_gw = NULL;
	u32 gw_throughput, orig_throughput, threshold;
	bool ret = false;

	threshold = atomic_read(&bat_priv->gw.sel_class);

	curr_gw = batadv_gw_node_get(bat_priv, curr_gw_orig);
	if (!curr_gw) {
		ret = true;
		goto out;
	}

	if (batadv_v_gw_throughput_get(curr_gw, &gw_throughput) < 0) {
		ret = true;
		goto out;
	}

	orig_gw = batadv_gw_node_get(bat_priv, orig_node);
	if (!orig_node)
		goto out;

	if (batadv_v_gw_throughput_get(orig_gw, &orig_throughput) < 0)
		goto out;

	if (orig_throughput < gw_throughput)
		goto out;

	if ((orig_throughput - gw_throughput) < threshold)
		goto out;

	batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
		   "Restarting gateway selection: better gateway found (throughput curr: %u, throughput new: %u)\n",
		   gw_throughput, orig_throughput);

	ret = true;
out:
	if (curr_gw)
		batadv_gw_node_put(curr_gw);
	if (orig_gw)
		batadv_gw_node_put(orig_gw);

	return ret;
}

/* fails if orig_node has no router */
static int batadv_v_gw_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 (%9u.%1u) %pM [%10s]: %u.%u/%u.%u MBit\n",
		   (curr_gw == gw_node ? "=>" : "  "),
		   gw_node->orig_node->orig,
		   router_ifinfo->bat_v.throughput / 10,
		   router_ifinfo->bat_v.throughput % 10, 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_put(curr_gw);
out:
	if (router_ifinfo)
		batadv_neigh_ifinfo_put(router_ifinfo);
	if (router)
		batadv_neigh_node_put(router);
	return ret;
}

/**
 * batadv_v_gw_print - print the gateway list
 * @bat_priv: the bat priv with all the soft interface information
 * @seq: gateway table seq_file struct
 */
static void batadv_v_gw_print(struct batadv_priv *bat_priv,
			      struct seq_file *seq)
{
	struct batadv_gw_node *gw_node;
	int gw_count = 0;

	seq_puts(seq,
		 "      Gateway        ( throughput)           Nexthop [outgoingIF]: advertised uplink bandwidth\n");

	rcu_read_lock();
	hlist_for_each_entry_rcu(gw_node, &bat_priv->gw.list, list) {
		/* fails if orig_node has no router */
		if (batadv_v_gw_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");
}

static struct batadv_algo_ops batadv_batman_v __read_mostly = {
	.name = "BATMAN_V",
	.iface = {
		.activate = batadv_v_iface_activate,
		.enable = batadv_v_iface_enable,
		.disable = batadv_v_iface_disable,
		.update_mac = batadv_v_iface_update_mac,
		.primary_set = batadv_v_primary_iface_set,
	},
	.neigh = {
		.hardif_init = batadv_v_hardif_neigh_init,
		.cmp = batadv_v_neigh_cmp,
		.is_similar_or_better = batadv_v_neigh_is_sob,
		.print = batadv_v_neigh_print,
	},
	.orig = {
		.print = batadv_v_orig_print,
	},
	.gw = {
		.store_sel_class = batadv_v_store_sel_class,
		.show_sel_class = batadv_v_show_sel_class,
		.get_best_gw_node = batadv_v_gw_get_best_gw_node,
		.is_eligible = batadv_v_gw_is_eligible,
		.print = batadv_v_gw_print,
	},
};

/**
 * batadv_v_hardif_init - initialize the algorithm specific fields in the
 *  hard-interface object
 * @hard_iface: the hard-interface to initialize
 */
void batadv_v_hardif_init(struct batadv_hard_iface *hard_iface)
{
	/* enable link throughput auto-detection by setting the throughput
	 * override to zero
	 */
	atomic_set(&hard_iface->bat_v.throughput_override, 0);
	atomic_set(&hard_iface->bat_v.elp_interval, 500);
}

/**
 * batadv_v_mesh_init - initialize the B.A.T.M.A.N. V private resources for a
 *  mesh
 * @bat_priv: the object representing the mesh interface to initialise
 *
 * Return: 0 on success or a negative error code otherwise
 */
int batadv_v_mesh_init(struct batadv_priv *bat_priv)
{
	int ret = 0;

	ret = batadv_v_ogm_init(bat_priv);
	if (ret < 0)
		return ret;

	/* set default throughput difference threshold to 5Mbps */
	atomic_set(&bat_priv->gw.sel_class, 50);

	return 0;
}

/**
 * batadv_v_mesh_free - free the B.A.T.M.A.N. V private resources for a mesh
 * @bat_priv: the object representing the mesh interface to free
 */
void batadv_v_mesh_free(struct batadv_priv *bat_priv)
{
	batadv_v_ogm_free(bat_priv);
}

/**
 * batadv_v_init - B.A.T.M.A.N. V initialization function
 *
 * Description: Takes care of initializing all the subcomponents.
 * It is invoked upon module load only.
 *
 * Return: 0 on success or a negative error code otherwise
 */
int __init batadv_v_init(void)
{
	int ret;

	/* B.A.T.M.A.N. V echo location protocol packet  */
	ret = batadv_recv_handler_register(BATADV_ELP,
					   batadv_v_elp_packet_recv);
	if (ret < 0)
		return ret;

	ret = batadv_recv_handler_register(BATADV_OGM2,
					   batadv_v_ogm_packet_recv);
	if (ret < 0)
		goto elp_unregister;

	ret = batadv_algo_register(&batadv_batman_v);
	if (ret < 0)
		goto ogm_unregister;

	return ret;

ogm_unregister:
	batadv_recv_handler_unregister(BATADV_OGM2);

elp_unregister:
	batadv_recv_handler_unregister(BATADV_ELP);

	return ret;
}