/* Copyright (C) 2007-2014 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 <linux/debugfs.h>
  #include <linux/slab.h>
  #include "icmp_socket.h"
  #include "send.h"
  #include "hash.h"
  #include "originator.h"
  #include "hard-interface.h"
  
  static struct batadv_socket_client *batadv_socket_client_hash[256];
  
  static void batadv_socket_add_packet(struct batadv_socket_client *socket_client,
  				     struct batadv_icmp_header *icmph,
  				     size_t icmp_len);
  
  void batadv_socket_init(void)
  {
  	memset(batadv_socket_client_hash, 0, sizeof(batadv_socket_client_hash));
  }
  
  static int batadv_socket_open(struct inode *inode, struct file *file)
  {
  	unsigned int i;
  	struct batadv_socket_client *socket_client;
  
  	if (!try_module_get(THIS_MODULE))
  		return -EBUSY;
  
  	nonseekable_open(inode, file);
  
  	socket_client = kmalloc(sizeof(*socket_client), GFP_KERNEL);
  	if (!socket_client) {
  		module_put(THIS_MODULE);
  		return -ENOMEM;
  	}
  
  	for (i = 0; i < ARRAY_SIZE(batadv_socket_client_hash); i++) {
  		if (!batadv_socket_client_hash[i]) {
  			batadv_socket_client_hash[i] = socket_client;
  			break;
  		}
  	}
  
  	if (i == ARRAY_SIZE(batadv_socket_client_hash)) {
  		pr_err("Error - can't add another packet client: maximum number of clients reached
  ");
  		kfree(socket_client);
  		module_put(THIS_MODULE);
  		return -EXFULL;
  	}
  
  	INIT_LIST_HEAD(&socket_client->queue_list);
  	socket_client->queue_len = 0;
  	socket_client->index = i;
  	socket_client->bat_priv = inode->i_private;
  	spin_lock_init(&socket_client->lock);
  	init_waitqueue_head(&socket_client->queue_wait);
  
  	file->private_data = socket_client;
  
  	return 0;
  }
  
  static int batadv_socket_release(struct inode *inode, struct file *file)
  {
  	struct batadv_socket_client *socket_client = file->private_data;
  	struct batadv_socket_packet *socket_packet;
  	struct list_head *list_pos, *list_pos_tmp;
  
  	spin_lock_bh(&socket_client->lock);
  
  	/* for all packets in the queue ... */
  	list_for_each_safe(list_pos, list_pos_tmp, &socket_client->queue_list) {
  		socket_packet = list_entry(list_pos,
  					   struct batadv_socket_packet, list);
  
  		list_del(list_pos);
  		kfree(socket_packet);
  	}
  
  	batadv_socket_client_hash[socket_client->index] = NULL;
  	spin_unlock_bh(&socket_client->lock);
  
  	kfree(socket_client);
  	module_put(THIS_MODULE);
  
  	return 0;
  }
  
  static ssize_t batadv_socket_read(struct file *file, char __user *buf,
  				  size_t count, loff_t *ppos)
  {
  	struct batadv_socket_client *socket_client = file->private_data;
  	struct batadv_socket_packet *socket_packet;
  	size_t packet_len;
  	int error;
  
  	if ((file->f_flags & O_NONBLOCK) && (socket_client->queue_len == 0))
  		return -EAGAIN;
  
  	if ((!buf) || (count < sizeof(struct batadv_icmp_packet)))
  		return -EINVAL;
  
  	if (!access_ok(VERIFY_WRITE, buf, count))
  		return -EFAULT;
  
  	error = wait_event_interruptible(socket_client->queue_wait,
  					 socket_client->queue_len);
  
  	if (error)
  		return error;
  
  	spin_lock_bh(&socket_client->lock);
  
  	socket_packet = list_first_entry(&socket_client->queue_list,
  					 struct batadv_socket_packet, list);
  	list_del(&socket_packet->list);
  	socket_client->queue_len--;
  
  	spin_unlock_bh(&socket_client->lock);
  
  	packet_len = min(count, socket_packet->icmp_len);
  	error = copy_to_user(buf, &socket_packet->icmp_packet, packet_len);
  
  	kfree(socket_packet);
  
  	if (error)
  		return -EFAULT;
  
  	return packet_len;
  }
  
  static ssize_t batadv_socket_write(struct file *file, const char __user *buff,
  				   size_t len, loff_t *off)
  {
  	struct batadv_socket_client *socket_client = file->private_data;
  	struct batadv_priv *bat_priv = socket_client->bat_priv;
  	struct batadv_hard_iface *primary_if = NULL;
  	struct sk_buff *skb;
  	struct batadv_icmp_packet_rr *icmp_packet_rr;
  	struct batadv_icmp_header *icmp_header;
  	struct batadv_orig_node *orig_node = NULL;
  	struct batadv_neigh_node *neigh_node = NULL;
  	size_t packet_len = sizeof(struct batadv_icmp_packet);
  
  	if (len < sizeof(struct batadv_icmp_header)) {
  		batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
  			   "Error - can't send packet from char device: invalid packet size
  ");
  		return -EINVAL;
  	}
  
  	primary_if = batadv_primary_if_get_selected(bat_priv);
  
  	if (!primary_if) {
  		len = -EFAULT;
  		goto out;
  	}
  
  	if (len >= BATADV_ICMP_MAX_PACKET_SIZE)
  		packet_len = BATADV_ICMP_MAX_PACKET_SIZE;
  	else
  		packet_len = len;
  
  	skb = netdev_alloc_skb_ip_align(NULL, packet_len + ETH_HLEN);
  	if (!skb) {
  		len = -ENOMEM;
  		goto out;
  	}
  
  	skb->priority = TC_PRIO_CONTROL;
  	skb_reserve(skb, ETH_HLEN);
  	icmp_header = (struct batadv_icmp_header *)skb_put(skb, packet_len);
  
  	if (copy_from_user(icmp_header, buff, packet_len)) {
  		len = -EFAULT;
  		goto free_skb;
  	}
  
  	if (icmp_header->packet_type != BATADV_ICMP) {
  		batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
  			   "Error - can't send packet from char device: got bogus packet type (expected: BAT_ICMP)
  ");
  		len = -EINVAL;
  		goto free_skb;
  	}
  
  	switch (icmp_header->msg_type) {
  	case BATADV_ECHO_REQUEST:
  		if (len < sizeof(struct batadv_icmp_packet)) {
  			batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
  				   "Error - can't send packet from char device: invalid packet size
  ");
  			len = -EINVAL;
  			goto free_skb;
  		}
  
  		if (atomic_read(&bat_priv->mesh_state) != BATADV_MESH_ACTIVE)
  			goto dst_unreach;
  
  		orig_node = batadv_orig_hash_find(bat_priv, icmp_header->dst);
  		if (!orig_node)
  			goto dst_unreach;
  
  		neigh_node = batadv_orig_router_get(orig_node,
  						    BATADV_IF_DEFAULT);
  		if (!neigh_node)
  			goto dst_unreach;
  
  		if (!neigh_node->if_incoming)
  			goto dst_unreach;
  
  		if (neigh_node->if_incoming->if_status != BATADV_IF_ACTIVE)
  			goto dst_unreach;
  
  		icmp_packet_rr = (struct batadv_icmp_packet_rr *)icmp_header;
  		if (packet_len == sizeof(*icmp_packet_rr))
  			memcpy(icmp_packet_rr->rr,
  			       neigh_node->if_incoming->net_dev->dev_addr,
  			       ETH_ALEN);
  
  		break;
  	default:
  		batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
  			   "Error - can't send packet from char device: got unknown message type
  ");
  		len = -EINVAL;
  		goto free_skb;
  	}
  
  	icmp_header->uid = socket_client->index;
  
  	if (icmp_header->version != BATADV_COMPAT_VERSION) {
  		icmp_header->msg_type = BATADV_PARAMETER_PROBLEM;
  		icmp_header->version = BATADV_COMPAT_VERSION;
  		batadv_socket_add_packet(socket_client, icmp_header,
  					 packet_len);
  		goto free_skb;
  	}
  
  	memcpy(icmp_header->orig, primary_if->net_dev->dev_addr, ETH_ALEN);
  
  	batadv_send_skb_packet(skb, neigh_node->if_incoming, neigh_node->addr);
  	goto out;
  
  dst_unreach:
  	icmp_header->msg_type = BATADV_DESTINATION_UNREACHABLE;
  	batadv_socket_add_packet(socket_client, icmp_header, packet_len);
  free_skb:
  	kfree_skb(skb);
  out:
  	if (primary_if)
  		batadv_hardif_free_ref(primary_if);
  	if (neigh_node)
  		batadv_neigh_node_free_ref(neigh_node);
  	if (orig_node)
  		batadv_orig_node_free_ref(orig_node);
  	return len;
  }
  
  static unsigned int batadv_socket_poll(struct file *file, poll_table *wait)
  {
  	struct batadv_socket_client *socket_client = file->private_data;
  
  	poll_wait(file, &socket_client->queue_wait, wait);
  
  	if (socket_client->queue_len > 0)
  		return POLLIN | POLLRDNORM;
  
  	return 0;
  }
  
  static const struct file_operations batadv_fops = {
  	.owner = THIS_MODULE,
  	.open = batadv_socket_open,
  	.release = batadv_socket_release,
  	.read = batadv_socket_read,
  	.write = batadv_socket_write,
  	.poll = batadv_socket_poll,
  	.llseek = no_llseek,
  };
  
  int batadv_socket_setup(struct batadv_priv *bat_priv)
  {
  	struct dentry *d;
  
  	if (!bat_priv->debug_dir)
  		goto err;
  
  	d = debugfs_create_file(BATADV_ICMP_SOCKET, S_IFREG | S_IWUSR | S_IRUSR,
  				bat_priv->debug_dir, bat_priv, &batadv_fops);
  	if (!d)
  		goto err;
  
  	return 0;
  
  err:
  	return -ENOMEM;
  }
  
  /**
   * batadv_socket_receive_packet - schedule an icmp packet to be sent to userspace
   *  on an icmp socket.
   * @socket_client: the socket this packet belongs to
   * @icmph: pointer to the header of the icmp packet
   * @icmp_len: total length of the icmp packet
   */
  static void batadv_socket_add_packet(struct batadv_socket_client *socket_client,
  				     struct batadv_icmp_header *icmph,
  				     size_t icmp_len)
  {
  	struct batadv_socket_packet *socket_packet;
  	size_t len;
  
  	socket_packet = kmalloc(sizeof(*socket_packet), GFP_ATOMIC);
  
  	if (!socket_packet)
  		return;
  
  	len = icmp_len;
  	/* check the maximum length before filling the buffer */
  	if (len > sizeof(socket_packet->icmp_packet))
  		len = sizeof(socket_packet->icmp_packet);
  
  	INIT_LIST_HEAD(&socket_packet->list);
  	memcpy(&socket_packet->icmp_packet, icmph, len);
  	socket_packet->icmp_len = len;
  
  	spin_lock_bh(&socket_client->lock);
  
  	/* while waiting for the lock the socket_client could have been
  	 * deleted
  	 */
  	if (!batadv_socket_client_hash[icmph->uid]) {
  		spin_unlock_bh(&socket_client->lock);
  		kfree(socket_packet);
  		return;
  	}
  
  	list_add_tail(&socket_packet->list, &socket_client->queue_list);
  	socket_client->queue_len++;
  
  	if (socket_client->queue_len > 100) {
  		socket_packet = list_first_entry(&socket_client->queue_list,
  						 struct batadv_socket_packet,
  						 list);
  
  		list_del(&socket_packet->list);
  		kfree(socket_packet);
  		socket_client->queue_len--;
  	}
  
  	spin_unlock_bh(&socket_client->lock);
  
  	wake_up(&socket_client->queue_wait);
  }
  
  /**
   * batadv_socket_receive_packet - schedule an icmp packet to be received
   *  locally and sent to userspace.
   * @icmph: pointer to the header of the icmp packet
   * @icmp_len: total length of the icmp packet
   */
  void batadv_socket_receive_packet(struct batadv_icmp_header *icmph,
  				  size_t icmp_len)
  {
  	struct batadv_socket_client *hash;
  
  	hash = batadv_socket_client_hash[icmph->uid];
  	if (hash)
  		batadv_socket_add_packet(hash, icmph, icmp_len);
  }