/*
   * net/tipc/discover.c

   *

   * Copyright (c) 2003-2006, 2014-2018, Ericsson AB

   * Copyright (c) 2005-2006, 2010-2011, Wind River Systems

   * All rights reserved.
   *

   * Redistribution and use in source and binary forms, with or without

   * modification, are permitted provided that the following conditions are met:
   *

   * 1. Redistributions of source code must retain the above copyright
   *    notice, this list of conditions and the following disclaimer.
   * 2. Redistributions in binary form must reproduce the above copyright
   *    notice, this list of conditions and the following disclaimer in the
   *    documentation and/or other materials provided with the distribution.
   * 3. Neither the names of the copyright holders nor the names of its
   *    contributors may be used to endorse or promote products derived from
   *    this software without specific prior written permission.

   *

   * Alternatively, this software may be distributed under the terms of the
   * GNU General Public License ("GPL") version 2 as published by the Free
   * Software Foundation.
   *
   * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
   * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
   * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
   * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
   * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
   * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
   * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
   * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE

   * POSSIBILITY OF SUCH DAMAGE.
   */
  
  #include "core.h"

  #include "node.h"

  #include "discover.h"

  /* min delay during bearer start up */

  #define TIPC_DISC_INIT	msecs_to_jiffies(125)

  /* max delay if bearer has no links */

  #define TIPC_DISC_FAST	msecs_to_jiffies(1000)

  /* max delay if bearer has links */

  #define TIPC_DISC_SLOW	msecs_to_jiffies(60000)

  /* indicates no timer in use */

  #define TIPC_DISC_INACTIVE	0xffffffff

  /**

   * struct tipc_discoverer - information about an ongoing link setup request

   * @bearer_id: identity of bearer issuing requests

   * @net: network namespace instance

   * @dest: destination address for request messages

   * @domain: network domain to which links can be established

   * @num_nodes: number of nodes currently discovered (i.e. with an active link)

   * @lock: spinlock for controlling access to requests

   * @skb: request message to be (repeatedly) sent

   * @timer: timer governing period between requests
   * @timer_intv: current interval between requests (in ms)
   */

  struct tipc_discoverer {

  	u32 bearer_id;

  	struct tipc_media_addr dest;

  	struct net *net;

  	u32 domain;

  	int num_nodes;

  	spinlock_t lock;

  	struct sk_buff *skb;

  	struct timer_list timer;

  	unsigned long timer_intv;

  };

  /**

   * tipc_disc_init_msg - initialize a link setup message

   * @net: the applicable net namespace

   * @type: message type (request or response)

   * @b: ptr to bearer issuing message

   */

  static void tipc_disc_init_msg(struct net *net, struct sk_buff *skb,

  			       u32 mtyp,  struct tipc_bearer *b)

  {

  	struct tipc_net *tn = tipc_net(net);

  	u32 dest_domain = b->domain;

  	struct tipc_msg *hdr;

  	hdr = buf_msg(skb);

  	tipc_msg_init(tn->trial_addr, hdr, LINK_CONFIG, mtyp,

  		      MAX_H_SIZE, dest_domain);

  	msg_set_size(hdr, MAX_H_SIZE + NODE_ID_LEN);

  	msg_set_non_seq(hdr, 1);
  	msg_set_node_sig(hdr, tn->random);
  	msg_set_node_capabilities(hdr, TIPC_NODE_CAPABILITIES);
  	msg_set_dest_domain(hdr, dest_domain);
  	msg_set_bc_netid(hdr, tn->net_id);
  	b->media->addr2msg(msg_media_addr(hdr), &b->addr);

  	msg_set_node_id(hdr, tipc_own_id(net));

  }

  static void tipc_disc_msg_xmit(struct net *net, u32 mtyp, u32 dst,
  			       u32 src, u32 sugg_addr,

  			       struct tipc_media_addr *maddr,
  			       struct tipc_bearer *b)
  {

  	struct tipc_msg *hdr;

  	struct sk_buff *skb;

  	skb = tipc_buf_acquire(MAX_H_SIZE + NODE_ID_LEN, GFP_ATOMIC);

  	if (!skb)
  		return;

  	hdr = buf_msg(skb);

  	tipc_disc_init_msg(net, skb, mtyp, b);

  	msg_set_sugg_node_addr(hdr, sugg_addr);
  	msg_set_dest_domain(hdr, dst);

  	tipc_bearer_xmit_skb(net, b->identity, skb, maddr);

  }
  
  /**

   * disc_dupl_alert - issue node address duplication alert

   * @b: pointer to bearer detecting duplication

   * @node_addr: duplicated node address
   * @media_addr: media address advertised by duplicated node
   */

  static void disc_dupl_alert(struct tipc_bearer *b, u32 node_addr,

  			    struct tipc_media_addr *media_addr)
  {

  	char media_addr_str[64];

  	tipc_media_addr_printf(media_addr_str, sizeof(media_addr_str),
  			       media_addr);

  	pr_warn("Duplicate %x using %s seen on <%s>
  ", node_addr,

  		media_addr_str, b->name);

  }

  /* tipc_disc_addr_trial(): - handle an address uniqueness trial from peer

   * Returns true if message should be dropped by caller, i.e., if it is a
   * trial message or we are inside trial period. Otherwise false.

   */

  static bool tipc_disc_addr_trial_msg(struct tipc_discoverer *d,
  				     struct tipc_media_addr *maddr,
  				     struct tipc_bearer *b,
  				     u32 dst, u32 src,
  				     u32 sugg_addr,
  				     u8 *peer_id,
  				     int mtyp)

  {
  	struct net *net = d->net;
  	struct tipc_net *tn = tipc_net(net);
  	bool trial = time_before(jiffies, tn->addr_trial_end);
  	u32 self = tipc_own_addr(net);
  
  	if (mtyp == DSC_TRIAL_FAIL_MSG) {
  		if (!trial)
  			return true;
  
  		/* Ignore if somebody else already gave new suggestion */
  		if (dst != tn->trial_addr)
  			return true;
  
  		/* Otherwise update trial address and restart trial period */
  		tn->trial_addr = sugg_addr;
  		msg_set_prevnode(buf_msg(d->skb), sugg_addr);
  		tn->addr_trial_end = jiffies + msecs_to_jiffies(1000);
  		return true;
  	}
  
  	/* Apply trial address if we just left trial period */
  	if (!trial && !self) {

  		tipc_sched_net_finalize(net, tn->trial_addr);
  		msg_set_prevnode(buf_msg(d->skb), tn->trial_addr);

  		msg_set_type(buf_msg(d->skb), DSC_REQ_MSG);
  	}

  	/* Accept regular link requests/responses only after trial period */

  	if (mtyp != DSC_TRIAL_MSG)

  		return trial;

  
  	sugg_addr = tipc_node_try_addr(net, peer_id, src);
  	if (sugg_addr)
  		tipc_disc_msg_xmit(net, DSC_TRIAL_FAIL_MSG, src,
  				   self, sugg_addr, maddr, b);
  	return true;
  }

  /**

   * tipc_disc_rcv - handle incoming discovery message (request or response)

   * @net: applicable net namespace
   * @skb: buffer containing message
   * @b: bearer that message arrived on

   */

  void tipc_disc_rcv(struct net *net, struct sk_buff *skb,

  		   struct tipc_bearer *b)

  {

  	struct tipc_net *tn = tipc_net(net);

  	struct tipc_msg *hdr = buf_msg(skb);

  	u16 caps = msg_node_capabilities(hdr);

  	bool legacy = tn->legacy_addr_format;

  	u32 sugg = msg_sugg_node_addr(hdr);

  	u32 signature = msg_node_sig(hdr);

  	u8 peer_id[NODE_ID_LEN] = {0,};

  	u32 dst = msg_dest_domain(hdr);

  	u32 net_id = msg_bc_netid(hdr);

  	struct tipc_media_addr maddr;
  	u32 src = msg_prevnode(hdr);

  	u32 mtyp = msg_type(hdr);

  	bool dupl_addr = false;

  	bool respond = false;

  	u32 self;

  	int err;

  	skb_linearize(skb);
  	hdr = buf_msg(skb);
  
  	if (caps & TIPC_NODE_ID128)
  		memcpy(peer_id, msg_node_id(hdr), NODE_ID_LEN);
  	else
  		sprintf(peer_id, "%x", src);

  	err = b->media->msg2addr(b, &maddr, msg_media_addr(hdr));

  	kfree_skb(skb);

  	if (err || maddr.broadcast) {
  		pr_warn_ratelimited("Rcv corrupt discovery message
  ");

  		return;

  	}
  	/* Ignore discovery messages from own node */
  	if (!memcmp(&maddr, &b->addr, sizeof(maddr)))

  		return;

  	if (net_id != tn->net_id)

  		return;

  	if (tipc_disc_addr_trial_msg(b->disc, &maddr, b, dst,
  				     src, sugg, peer_id, mtyp))
  		return;
  	self = tipc_own_addr(net);
  
  	/* Message from somebody using this node's address */

  	if (in_own_node(net, src)) {
  		disc_dupl_alert(b, self, &maddr);

  		return;

  	}

  	if (!tipc_in_scope(legacy, dst, self))
  		return;
  	if (!tipc_in_scope(legacy, b->domain, src))
  		return;

  	tipc_node_check_dest(net, src, peer_id, b, caps, signature,

  			     &maddr, &respond, &dupl_addr);
  	if (dupl_addr)

  		disc_dupl_alert(b, src, &maddr);
  	if (!respond)
  		return;
  	if (mtyp != DSC_REQ_MSG)
  		return;

  	tipc_disc_msg_xmit(net, DSC_RESP_MSG, src, self, 0, &maddr, b);

  }

  /* tipc_disc_add_dest - increment set of discovered nodes

   */

  void tipc_disc_add_dest(struct tipc_discoverer *d)

  {

  	spin_lock_bh(&d->lock);
  	d->num_nodes++;
  	spin_unlock_bh(&d->lock);

  }

  /* tipc_disc_remove_dest - decrement set of discovered nodes

   */

  void tipc_disc_remove_dest(struct tipc_discoverer *d)

  {

  	int intv, num;

  	spin_lock_bh(&d->lock);
  	d->num_nodes--;
  	num = d->num_nodes;
  	intv = d->timer_intv;
  	if (!num && (intv == TIPC_DISC_INACTIVE || intv > TIPC_DISC_FAST))  {
  		d->timer_intv = TIPC_DISC_INIT;
  		mod_timer(&d->timer, jiffies + d->timer_intv);
  	}
  	spin_unlock_bh(&d->lock);

  }

  /* tipc_disc_timeout - send a periodic link setup request

   * Called whenever a link setup request timer associated with a bearer expires.

   * - Keep doubling time between sent request until limit is reached;
   * - Hold at fast polling rate if we don't have any associated nodes
   * - Otherwise hold at slow polling rate

   */

  static void tipc_disc_timeout(struct timer_list *t)

  {

  	struct tipc_discoverer *d = from_timer(d, t, timer);

  	struct tipc_net *tn = tipc_net(d->net);

  	struct tipc_media_addr maddr;
  	struct sk_buff *skb = NULL;

  	struct net *net = d->net;

  	u32 bearer_id;

  	spin_lock_bh(&d->lock);

  	/* Stop searching if only desired node has been found */

  	if (tipc_node(d->domain) && d->num_nodes) {
  		d->timer_intv = TIPC_DISC_INACTIVE;

  		goto exit;

  	}

  	/* Did we just leave trial period ? */
  	if (!time_before(jiffies, tn->addr_trial_end) && !tipc_own_addr(net)) {
  		mod_timer(&d->timer, jiffies + TIPC_DISC_INIT);
  		spin_unlock_bh(&d->lock);
  		tipc_sched_net_finalize(net, tn->trial_addr);
  		return;

  	}

  	/* Adjust timeout interval according to discovery phase */

  	if (time_before(jiffies, tn->addr_trial_end)) {
  		d->timer_intv = TIPC_DISC_INIT;
  	} else {
  		d->timer_intv *= 2;
  		if (d->num_nodes && d->timer_intv > TIPC_DISC_SLOW)
  			d->timer_intv = TIPC_DISC_SLOW;
  		else if (!d->num_nodes && d->timer_intv > TIPC_DISC_FAST)
  			d->timer_intv = TIPC_DISC_FAST;

  		msg_set_type(buf_msg(d->skb), DSC_REQ_MSG);
  		msg_set_prevnode(buf_msg(d->skb), tn->trial_addr);

  	}

  	mod_timer(&d->timer, jiffies + d->timer_intv);
  	memcpy(&maddr, &d->dest, sizeof(maddr));
  	skb = skb_clone(d->skb, GFP_ATOMIC);

  	bearer_id = d->bearer_id;

  exit:

  	spin_unlock_bh(&d->lock);
  	if (skb)
  		tipc_bearer_xmit_skb(net, bearer_id, skb, &maddr);

  }
  
  /**

   * tipc_disc_create - create object to send periodic link setup requests

   * @net: the applicable net namespace

   * @b: ptr to bearer issuing requests

   * @dest: destination address for request messages

   * @dest_domain: network domain to which links can be established

   *

   * Returns 0 if successful, otherwise -errno.

   */

  int tipc_disc_create(struct net *net, struct tipc_bearer *b,

  		     struct tipc_media_addr *dest, struct sk_buff **skb)

  {

  	struct tipc_net *tn = tipc_net(net);

  	struct tipc_discoverer *d;

  	d = kmalloc(sizeof(*d), GFP_ATOMIC);
  	if (!d)

  		return -ENOMEM;

  	d->skb = tipc_buf_acquire(MAX_H_SIZE + NODE_ID_LEN, GFP_ATOMIC);

  	if (!d->skb) {
  		kfree(d);

  		return -ENOMEM;

  	}

  	tipc_disc_init_msg(net, d->skb, DSC_REQ_MSG, b);

  
  	/* Do we need an address trial period first ? */
  	if (!tipc_own_addr(net)) {
  		tn->addr_trial_end = jiffies + msecs_to_jiffies(1000);
  		msg_set_type(buf_msg(d->skb), DSC_TRIAL_MSG);
  	}

  	memcpy(&d->dest, dest, sizeof(*dest));
  	d->net = net;
  	d->bearer_id = b->identity;
  	d->domain = b->domain;
  	d->num_nodes = 0;
  	d->timer_intv = TIPC_DISC_INIT;
  	spin_lock_init(&d->lock);
  	timer_setup(&d->timer, tipc_disc_timeout, 0);
  	mod_timer(&d->timer, jiffies + d->timer_intv);
  	b->disc = d;
  	*skb = skb_clone(d->skb, GFP_ATOMIC);

  	return 0;
  }
  
  /**
   * tipc_disc_delete - destroy object sending periodic link setup requests

   * @d: ptr to link duest structure

   */

  void tipc_disc_delete(struct tipc_discoverer *d)

  {

  	del_timer_sync(&d->timer);
  	kfree_skb(d->skb);
  	kfree(d);

  }

  
  /**
   * tipc_disc_reset - reset object to send periodic link setup requests

   * @net: the applicable net namespace

   * @b: ptr to bearer issuing requests

   * @dest_domain: network domain to which links can be established
   */

  void tipc_disc_reset(struct net *net, struct tipc_bearer *b)

  {

  	struct tipc_discoverer *d = b->disc;
  	struct tipc_media_addr maddr;

  	struct sk_buff *skb;

  	spin_lock_bh(&d->lock);
  	tipc_disc_init_msg(net, d->skb, DSC_REQ_MSG, b);
  	d->net = net;
  	d->bearer_id = b->identity;
  	d->domain = b->domain;
  	d->num_nodes = 0;
  	d->timer_intv = TIPC_DISC_INIT;
  	memcpy(&maddr, &d->dest, sizeof(maddr));
  	mod_timer(&d->timer, jiffies + d->timer_intv);
  	skb = skb_clone(d->skb, GFP_ATOMIC);
  	spin_unlock_bh(&d->lock);

  	if (skb)

  		tipc_bearer_xmit_skb(net, b->identity, skb, &maddr);

  }