// SPDX-License-Identifier: GPL-2.0

  /* Copyright (C) 2007-2019  B.A.T.M.A.N. contributors:

   *
   * Marek Lindner

   */

  #include "icmp_socket.h"

  #include "main.h"

  
  #include <linux/atomic.h>
  #include <linux/compiler.h>

  #include <linux/debugfs.h>

  #include <linux/errno.h>
  #include <linux/etherdevice.h>

  #include <linux/eventpoll.h>

  #include <linux/export.h>
  #include <linux/fcntl.h>
  #include <linux/fs.h>

  #include <linux/gfp.h>

  #include <linux/if_ether.h>
  #include <linux/kernel.h>
  #include <linux/list.h>
  #include <linux/module.h>
  #include <linux/netdevice.h>
  #include <linux/pkt_sched.h>
  #include <linux/poll.h>
  #include <linux/printk.h>
  #include <linux/sched.h> /* for linux/wait.h */
  #include <linux/skbuff.h>

  #include <linux/slab.h>

  #include <linux/spinlock.h>

  #include <linux/stddef.h>
  #include <linux/string.h>
  #include <linux/uaccess.h>
  #include <linux/wait.h>

  #include <uapi/linux/batadv_packet.h>

  #include "debugfs.h"

  #include "hard-interface.h"

  #include "log.h"

  #include "originator.h"

  #include "send.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);

  /**
   * batadv_socket_init() - Initialize soft interface independent socket data
   */

  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;

  	batadv_debugfs_deprecated(file, "");

  	stream_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 *client = file->private_data;
  	struct batadv_socket_packet *packet, *tmp;

  	spin_lock_bh(&client->lock);

  
  	/* for all packets in the queue ... */

  	list_for_each_entry_safe(packet, tmp, &client->queue_list, list) {
  		list_del(&packet->list);
  		kfree(packet);

  	}

  	batadv_socket_client_hash[client->index] = NULL;
  	spin_unlock_bh(&client->lock);

  	kfree(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(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);

  	u8 *addr;

  	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 = 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)) {
  			addr = neigh_node->if_incoming->net_dev->dev_addr;
  			ether_addr_copy(icmp_packet_rr->rr[0], addr);
  		}

  
  		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;
  	}

  	ether_addr_copy(icmp_header->orig, primary_if->net_dev->dev_addr);

  	batadv_send_unicast_skb(skb, neigh_node);

  	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_put(primary_if);

  	if (neigh_node)

  		batadv_neigh_node_put(neigh_node);

  	if (orig_node)

  		batadv_orig_node_put(orig_node);

  	return len;
  }

  static __poll_t 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 EPOLLIN | EPOLLRDNORM;

  
  	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,
  };

  /**
   * batadv_socket_setup() - Create debugfs "socket" file
   * @bat_priv: the bat priv with all the soft interface information

   */

  void batadv_socket_setup(struct batadv_priv *bat_priv)

  {

  	debugfs_create_file(BATADV_ICMP_SOCKET, 0600, bat_priv->debug_dir,
  			    bat_priv, &batadv_fops);

  }

  /**

   * batadv_socket_add_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);

  }