/*
   * net/tipc/discover.c

   *

   * Copyright (c) 2003-2006, 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 "link.h"

  #include "discover.h"

  
  #define TIPC_LINK_REQ_INIT	125	/* min delay during bearer start up */

  #define TIPC_LINK_REQ_FAST	1000	/* max delay if bearer has no links */
  #define TIPC_LINK_REQ_SLOW	60000	/* max delay if bearer has links */
  #define TIPC_LINK_REQ_INACTIVE	0xffffffff /* indicates no timer in use */

  
  
  /**

   * struct tipc_link_req - information about an ongoing link setup request

   * @bearer: bearer issuing requests
   * @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)

   * @buf: request message to be (repeatedly) sent
   * @timer: timer governing period between requests
   * @timer_intv: current interval between requests (in ms)
   */

  struct tipc_link_req {

  	struct tipc_bearer *bearer;

  	struct tipc_media_addr dest;

  	u32 domain;

  	int num_nodes;

  	struct sk_buff *buf;
  	struct timer_list timer;
  	unsigned int timer_intv;
  };

  /**

   * tipc_disc_init_msg - initialize a link setup message

   * @type: message type (request or response)

   * @dest_domain: network domain of node(s) which should respond to message
   * @b_ptr: ptr to bearer issuing message
   */

  static struct sk_buff *tipc_disc_init_msg(u32 type,

  					  u32 dest_domain,

  					  struct tipc_bearer *b_ptr)

  {

  	struct sk_buff *buf = tipc_buf_acquire(INT_H_SIZE);

  	struct tipc_msg *msg;
  
  	if (buf) {
  		msg = buf_msg(buf);

  		tipc_msg_init(msg, LINK_CONFIG, type, INT_H_SIZE, dest_domain);

  		msg_set_non_seq(msg, 1);

  		msg_set_dest_domain(msg, dest_domain);
  		msg_set_bc_netid(msg, tipc_net_id);

  		b_ptr->media->addr2msg(&b_ptr->addr, msg_media_addr(msg));

  	}
  	return buf;
  }
  
  /**

   * disc_dupl_alert - issue node address duplication alert
   * @b_ptr: 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_ptr, u32 node_addr,

  			    struct tipc_media_addr *media_addr)
  {
  	char node_addr_str[16];
  	char media_addr_str[64];
  	struct print_buf pb;

  	tipc_addr_string_fill(node_addr_str, node_addr);

  	tipc_printbuf_init(&pb, media_addr_str, sizeof(media_addr_str));
  	tipc_media_addr_printf(&pb, media_addr);
  	tipc_printbuf_validate(&pb);
  	warn("Duplicate %s using %s seen on <%s>
  ",

  	     node_addr_str, media_addr_str, b_ptr->name);

  }
  
  /**

   * tipc_disc_recv_msg - handle incoming link setup message (request or response)

   * @buf: buffer containing message

   * @b_ptr: bearer that message arrived on

   */

  void tipc_disc_recv_msg(struct sk_buff *buf, struct tipc_bearer *b_ptr)

  {

  	struct tipc_node *n_ptr;

  	struct tipc_link *link;

  	struct tipc_media_addr media_addr, *addr;
  	struct sk_buff *rbuf;

  	struct tipc_msg *msg = buf_msg(buf);
  	u32 dest = msg_dest_domain(msg);
  	u32 orig = msg_prevnode(msg);
  	u32 net_id = msg_bc_netid(msg);
  	u32 type = msg_type(msg);

  	int link_fully_up;

  	media_addr.broadcast = 1;

  	b_ptr->media->msg2addr(&media_addr, msg_media_addr(msg));

  	buf_discard(buf);

  	/* Validate discovery message from requesting node */

  	if (net_id != tipc_net_id)
  		return;

  	if (media_addr.broadcast)
  		return;

  	if (!tipc_addr_domain_valid(dest))

  		return;

  	if (!tipc_addr_node_valid(orig))

  		return;

  	if (orig == tipc_own_addr) {

  		if (memcmp(&media_addr, &b_ptr->addr, sizeof(media_addr)))

  			disc_dupl_alert(b_ptr, tipc_own_addr, &media_addr);

  		return;

  	}

  	if (!tipc_in_scope(dest, tipc_own_addr))

  		return;

  	if (!tipc_in_scope(b_ptr->link_req->domain, orig))

  		return;

  	/* Locate structure corresponding to requesting node */
  	n_ptr = tipc_node_find(orig);
  	if (!n_ptr) {
  		n_ptr = tipc_node_create(orig);
  		if (!n_ptr)

  			return;

  	}
  	tipc_node_lock(n_ptr);

  	link = n_ptr->links[b_ptr->identity];
  
  	/* Create a link endpoint for this bearer, if necessary */
  	if (!link) {

  		link = tipc_link_create(n_ptr, b_ptr, &media_addr);

  		if (!link) {

  			tipc_node_unlock(n_ptr);
  			return;

  		}

  	}
  
  	/*
  	 * Ensure requesting node's media address is correct
  	 *
  	 * If media address doesn't match and the link is working, reject the
  	 * request (must be from a duplicate node).
  	 *
  	 * If media address doesn't match and the link is not working, accept
  	 * the new media address and reset the link to ensure it starts up
  	 * cleanly.
  	 */
  	addr = &link->media_addr;
  	if (memcmp(addr, &media_addr, sizeof(*addr))) {
  		if (tipc_link_is_up(link) || (!link->started)) {
  			disc_dupl_alert(b_ptr, orig, &media_addr);
  			tipc_node_unlock(n_ptr);

  			return;

  		}

  		warn("Resetting link <%s>, peer interface address changed
  ",
  		     link->name);
  		memcpy(addr, &media_addr, sizeof(*addr));
  		tipc_link_reset(link);
  	}
  
  	/* Accept discovery message & send response, if necessary */
  	link_fully_up = link_working_working(link);

  	if ((type == DSC_REQ_MSG) && !link_fully_up && !b_ptr->blocked) {

  		rbuf = tipc_disc_init_msg(DSC_RESP_MSG, orig, b_ptr);
  		if (rbuf) {
  			b_ptr->media->send_msg(rbuf, b_ptr, &media_addr);
  			buf_discard(rbuf);
  		}

  	}

  
  	tipc_node_unlock(n_ptr);

  }
  
  /**

   * disc_update - update frequency of periodic link setup requests

   * @req: ptr to link request structure

   *
   * Reinitiates discovery process if discovery object has no associated nodes
   * and is either not currently searching or is searching at a slow rate

   */

  static void disc_update(struct tipc_link_req *req)

  {

  	if (!req->num_nodes) {
  		if ((req->timer_intv == TIPC_LINK_REQ_INACTIVE) ||
  		    (req->timer_intv > TIPC_LINK_REQ_FAST)) {
  			req->timer_intv = TIPC_LINK_REQ_INIT;

  			k_start_timer(&req->timer, req->timer_intv);
  		}

  	}

  }

  
  /**

   * tipc_disc_add_dest - increment set of discovered nodes
   * @req: ptr to link request structure
   */

  void tipc_disc_add_dest(struct tipc_link_req *req)

  {
  	req->num_nodes++;

  }
  
  /**
   * tipc_disc_remove_dest - decrement set of discovered nodes
   * @req: ptr to link request structure
   */

  void tipc_disc_remove_dest(struct tipc_link_req *req)

  {
  	req->num_nodes--;
  	disc_update(req);
  }
  
  /**

   * disc_send_msg - send link setup request message
   * @req: ptr to link request structure
   */

  static void disc_send_msg(struct tipc_link_req *req)

  {
  	if (!req->bearer->blocked)
  		tipc_bearer_send(req->bearer, req->buf, &req->dest);
  }
  
  /**

   * disc_timeout - send a periodic link setup request
   * @req: ptr to link request structure

   *

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

  static void disc_timeout(struct tipc_link_req *req)

  {

  	int max_delay;

  	spin_lock_bh(&req->bearer->lock);

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

  	if (tipc_node(req->domain) && req->num_nodes) {
  		req->timer_intv = TIPC_LINK_REQ_INACTIVE;
  		goto exit;

  	}

  	/*
  	 * Send discovery message, then update discovery timer
  	 *
  	 * Keep doubling time between requests until limit is reached;
  	 * hold at fast polling rate if don't have any associated nodes,
  	 * otherwise hold at slow polling rate
  	 */
  
  	disc_send_msg(req);
  
  	req->timer_intv *= 2;
  	if (req->num_nodes)
  		max_delay = TIPC_LINK_REQ_SLOW;
  	else
  		max_delay = TIPC_LINK_REQ_FAST;
  	if (req->timer_intv > max_delay)
  		req->timer_intv = max_delay;
  
  	k_start_timer(&req->timer, req->timer_intv);
  exit:

  	spin_unlock_bh(&req->bearer->lock);

  }
  
  /**

   * tipc_disc_create - create object to send periodic link setup requests

   * @b_ptr: 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 tipc_bearer *b_ptr,
  		     struct tipc_media_addr *dest, u32 dest_domain)

  {

  	struct tipc_link_req *req;

  	req = kmalloc(sizeof(*req), GFP_ATOMIC);

  	if (!req)

  		return -ENOMEM;

  	req->buf = tipc_disc_init_msg(DSC_REQ_MSG, dest_domain, b_ptr);

  	if (!req->buf) {
  		kfree(req);

  		return -ENOMSG;

  	}
  
  	memcpy(&req->dest, dest, sizeof(*dest));
  	req->bearer = b_ptr;

  	req->domain = dest_domain;

  	req->num_nodes = 0;

  	req->timer_intv = TIPC_LINK_REQ_INIT;
  	k_init_timer(&req->timer, (Handler)disc_timeout, (unsigned long)req);
  	k_start_timer(&req->timer, req->timer_intv);

  	b_ptr->link_req = req;

  	disc_send_msg(req);

  	return 0;
  }
  
  /**
   * tipc_disc_delete - destroy object sending periodic link setup requests
   * @req: ptr to link request structure
   */

  void tipc_disc_delete(struct tipc_link_req *req)

  {
  	k_cancel_timer(&req->timer);
  	k_term_timer(&req->timer);
  	buf_discard(req->buf);
  	kfree(req);

  }