// SPDX-License-Identifier: GPL-2.0

  /* Copyright (C) 2009-2019  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 "gateway_common.h"

  #include "main.h"
  
  #include <linux/atomic.h>
  #include <linux/byteorder/generic.h>

  #include <linux/errno.h>

  #include <linux/kernel.h>

  #include <linux/math64.h>

  #include <linux/netdevice.h>
  #include <linux/stddef.h>
  #include <linux/string.h>

  #include <uapi/linux/batadv_packet.h>

  #include <uapi/linux/batman_adv.h>

  #include "gateway_client.h"

  #include "log.h"

  #include "tvlv.h"

  /**

   * batadv_parse_throughput() - parse supplied string buffer to extract
   *  throughput information

   * @net_dev: the soft interface net device
   * @buff: string buffer to parse

   * @description: text shown when throughput string cannot be parsed
   * @throughput: pointer holding the returned throughput information

   *

   * Return: false on parse error and true otherwise.

   */

  bool batadv_parse_throughput(struct net_device *net_dev, char *buff,
  			     const char *description, u32 *throughput)

  {

  	enum batadv_bandwidth_units bw_unit_type = BATADV_BW_UNIT_KBIT;

  	u64 lthroughput;
  	char *tmp_ptr;

  	int ret;

  	if (strlen(buff) > 4) {
  		tmp_ptr = buff + strlen(buff) - 4;

  		if (strncasecmp(tmp_ptr, "mbit", 4) == 0)

  			bw_unit_type = BATADV_BW_UNIT_MBIT;

  		if (strncasecmp(tmp_ptr, "kbit", 4) == 0 ||
  		    bw_unit_type == BATADV_BW_UNIT_MBIT)

  			*tmp_ptr = '\0';
  	}

  	ret = kstrtou64(buff, 10, &lthroughput);

  	if (ret) {

  		batadv_err(net_dev,

  			   "Invalid throughput speed for %s: %s
  ",
  			   description, buff);

  		return false;
  	}

  	switch (bw_unit_type) {
  	case BATADV_BW_UNIT_MBIT:

  		/* prevent overflow */

  		if (U64_MAX / 10 < lthroughput) {

  			batadv_err(net_dev,

  				   "Throughput speed for %s too large: %s
  ",
  				   description, buff);

  			return false;
  		}

  		lthroughput *= 10;

  		break;
  	case BATADV_BW_UNIT_KBIT:
  	default:

  		lthroughput = div_u64(lthroughput, 100);

  		break;
  	}

  	if (lthroughput > U32_MAX) {

  		batadv_err(net_dev,

  			   "Throughput speed for %s too large: %s
  ",
  			   description, buff);

  		return false;
  	}

  	*throughput = lthroughput;

  	return true;
  }

  /**

   * batadv_parse_gw_bandwidth() - parse supplied string buffer to extract
   *  download and upload bandwidth information

   * @net_dev: the soft interface net device
   * @buff: string buffer to parse
   * @down: pointer holding the returned download bandwidth information
   * @up: pointer holding the returned upload bandwidth information
   *
   * Return: false on parse error and true otherwise.
   */
  static bool batadv_parse_gw_bandwidth(struct net_device *net_dev, char *buff,
  				      u32 *down, u32 *up)
  {
  	char *slash_ptr;
  	bool ret;

  	slash_ptr = strchr(buff, '/');
  	if (slash_ptr)
  		*slash_ptr = 0;

  	ret = batadv_parse_throughput(net_dev, buff, "download gateway speed",
  				      down);
  	if (!ret)
  		return false;

  	/* we also got some upload info */
  	if (slash_ptr) {
  		ret = batadv_parse_throughput(net_dev, slash_ptr + 1,
  					      "upload gateway speed", up);
  		if (!ret)

  			return false;

  	}
  
  	return true;
  }

  /**

   * batadv_gw_tvlv_container_update() - update the gw tvlv container after
   *  gateway setting change

   * @bat_priv: the bat priv with all the soft interface information
   */
  void batadv_gw_tvlv_container_update(struct batadv_priv *bat_priv)
  {
  	struct batadv_tvlv_gateway_data gw;

  	u32 down, up;

  	char gw_mode;

  	gw_mode = atomic_read(&bat_priv->gw.mode);

  
  	switch (gw_mode) {
  	case BATADV_GW_MODE_OFF:
  	case BATADV_GW_MODE_CLIENT:
  		batadv_tvlv_container_unregister(bat_priv, BATADV_TVLV_GW, 1);
  		break;
  	case BATADV_GW_MODE_SERVER:
  		down = atomic_read(&bat_priv->gw.bandwidth_down);
  		up = atomic_read(&bat_priv->gw.bandwidth_up);
  		gw.bandwidth_down = htonl(down);
  		gw.bandwidth_up = htonl(up);
  		batadv_tvlv_container_register(bat_priv, BATADV_TVLV_GW, 1,
  					       &gw, sizeof(gw));
  		break;
  	}
  }

  /**
   * batadv_gw_bandwidth_set() - Parse and set download/upload gateway bandwidth
   *  from supplied string buffer
   * @net_dev: netdev struct of the soft interface
   * @buff: the buffer containing the user data
   * @count: number of bytes in the buffer
   *
   * Return: 'count' on success or a negative error code in case of failure
   */

  ssize_t batadv_gw_bandwidth_set(struct net_device *net_dev, char *buff,
  				size_t count)

  {

  	struct batadv_priv *bat_priv = netdev_priv(net_dev);

  	u32 down_curr;
  	u32 up_curr;
  	u32 down_new = 0;
  	u32 up_new = 0;

  	bool ret;

  	down_curr = (unsigned int)atomic_read(&bat_priv->gw.bandwidth_down);
  	up_curr = (unsigned int)atomic_read(&bat_priv->gw.bandwidth_up);
  
  	ret = batadv_parse_gw_bandwidth(net_dev, buff, &down_new, &up_new);

  	if (!ret)

  		return -EINVAL;

  	if (!down_new)
  		down_new = 1;

  	if (!up_new)
  		up_new = down_new / 5;

  	if (!up_new)
  		up_new = 1;

  	if (down_curr == down_new && up_curr == up_new)

  		return count;

  	batadv_gw_reselect(bat_priv);

  	batadv_info(net_dev,

  		    "Changing gateway bandwidth from: '%u.%u/%u.%u MBit' to: '%u.%u/%u.%u MBit'
  ",
  		    down_curr / 10, down_curr % 10, up_curr / 10, up_curr % 10,
  		    down_new / 10, down_new % 10, up_new / 10, up_new % 10);

  	atomic_set(&bat_priv->gw.bandwidth_down, down_new);
  	atomic_set(&bat_priv->gw.bandwidth_up, up_new);
  	batadv_gw_tvlv_container_update(bat_priv);

  	return count;
  }

  
  /**

   * batadv_gw_tvlv_ogm_handler_v1() - process incoming gateway tvlv container

   * @bat_priv: the bat priv with all the soft interface information
   * @orig: the orig_node of the ogm
   * @flags: flags indicating the tvlv state (see batadv_tvlv_handler_flags)
   * @tvlv_value: tvlv buffer containing the gateway data
   * @tvlv_value_len: tvlv buffer length
   */
  static void batadv_gw_tvlv_ogm_handler_v1(struct batadv_priv *bat_priv,
  					  struct batadv_orig_node *orig,

  					  u8 flags,
  					  void *tvlv_value, u16 tvlv_value_len)

  {
  	struct batadv_tvlv_gateway_data gateway, *gateway_ptr;
  
  	/* only fetch the tvlv value if the handler wasn't called via the
  	 * CIFNOTFND flag and if there is data to fetch
  	 */

  	if (flags & BATADV_TVLV_HANDLER_OGM_CIFNOTFND ||
  	    tvlv_value_len < sizeof(gateway)) {

  		gateway.bandwidth_down = 0;
  		gateway.bandwidth_up = 0;
  	} else {
  		gateway_ptr = tvlv_value;
  		gateway.bandwidth_down = gateway_ptr->bandwidth_down;
  		gateway.bandwidth_up = gateway_ptr->bandwidth_up;

  		if (gateway.bandwidth_down == 0 ||
  		    gateway.bandwidth_up == 0) {

  			gateway.bandwidth_down = 0;
  			gateway.bandwidth_up = 0;
  		}
  	}
  
  	batadv_gw_node_update(bat_priv, orig, &gateway);

  	/* restart gateway selection */

  	if (gateway.bandwidth_down != 0 &&
  	    atomic_read(&bat_priv->gw.mode) == BATADV_GW_MODE_CLIENT)

  		batadv_gw_check_election(bat_priv, orig);
  }
  
  /**

   * batadv_gw_init() - initialise the gateway handling internals

   * @bat_priv: the bat priv with all the soft interface information
   */
  void batadv_gw_init(struct batadv_priv *bat_priv)
  {

  	if (bat_priv->algo_ops->gw.init_sel_class)
  		bat_priv->algo_ops->gw.init_sel_class(bat_priv);
  	else
  		atomic_set(&bat_priv->gw.sel_class, 1);

  	batadv_tvlv_handler_register(bat_priv, batadv_gw_tvlv_ogm_handler_v1,
  				     NULL, BATADV_TVLV_GW, 1,
  				     BATADV_TVLV_HANDLER_OGM_CIFNOTFND);
  }
  
  /**

   * batadv_gw_free() - free the gateway handling internals

   * @bat_priv: the bat priv with all the soft interface information
   */
  void batadv_gw_free(struct batadv_priv *bat_priv)
  {
  	batadv_tvlv_container_unregister(bat_priv, BATADV_TVLV_GW, 1);
  	batadv_tvlv_handler_unregister(bat_priv, BATADV_TVLV_GW, 1);
  }