/*
   * net/tipc/subscr.c: TIPC network topology service
   *
   * Copyright (c) 2000-2006, Ericsson AB
   * Copyright (c) 2005-2007, 2010-2013, 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 "name_table.h"
  #include "port.h"
  #include "subscr.h"
  
  /**
   * struct tipc_subscriber - TIPC network topology subscriber
   * @conid: connection identifier to server connecting to subscriber
   * @lock: control access to subscriber
   * @subscription_list: list of subscription objects for this subscriber
   */
  struct tipc_subscriber {
  	int conid;
  	spinlock_t lock;
  	struct list_head subscription_list;
  };
  
  static void subscr_conn_msg_event(int conid, struct sockaddr_tipc *addr,
  				  void *usr_data, void *buf, size_t len);
  static void *subscr_named_msg_event(int conid);
  static void subscr_conn_shutdown_event(int conid, void *usr_data);
  
  static atomic_t subscription_count = ATOMIC_INIT(0);
  
  static struct sockaddr_tipc topsrv_addr __read_mostly = {
  	.family			= AF_TIPC,
  	.addrtype		= TIPC_ADDR_NAMESEQ,
  	.addr.nameseq.type	= TIPC_TOP_SRV,
  	.addr.nameseq.lower	= TIPC_TOP_SRV,
  	.addr.nameseq.upper	= TIPC_TOP_SRV,
  	.scope			= TIPC_NODE_SCOPE
  };
  
  static struct tipc_server topsrv __read_mostly = {
  	.saddr			= &topsrv_addr,
  	.imp			= TIPC_CRITICAL_IMPORTANCE,
  	.type			= SOCK_SEQPACKET,
  	.max_rcvbuf_size	= sizeof(struct tipc_subscr),
  	.name			= "topology_server",
  	.tipc_conn_recvmsg	= subscr_conn_msg_event,
  	.tipc_conn_new		= subscr_named_msg_event,
  	.tipc_conn_shutdown	= subscr_conn_shutdown_event,
  };
  
  /**
   * htohl - convert value to endianness used by destination
   * @in: value to convert
   * @swap: non-zero if endianness must be reversed
   *
   * Returns converted value
   */
  static u32 htohl(u32 in, int swap)
  {
  	return swap ? swab32(in) : in;
  }
  
  static void subscr_send_event(struct tipc_subscription *sub, u32 found_lower,
  			      u32 found_upper, u32 event, u32 port_ref,
  			      u32 node)
  {
  	struct tipc_subscriber *subscriber = sub->subscriber;
  	struct kvec msg_sect;
  
  	msg_sect.iov_base = (void *)&sub->evt;
  	msg_sect.iov_len = sizeof(struct tipc_event);
  	sub->evt.event = htohl(event, sub->swap);
  	sub->evt.found_lower = htohl(found_lower, sub->swap);
  	sub->evt.found_upper = htohl(found_upper, sub->swap);
  	sub->evt.port.ref = htohl(port_ref, sub->swap);
  	sub->evt.port.node = htohl(node, sub->swap);
  	tipc_conn_sendmsg(&topsrv, subscriber->conid, NULL, msg_sect.iov_base,
  			  msg_sect.iov_len);
  }
  
  /**
   * tipc_subscr_overlap - test for subscription overlap with the given values
   *
   * Returns 1 if there is overlap, otherwise 0.
   */
  int tipc_subscr_overlap(struct tipc_subscription *sub, u32 found_lower,
  			u32 found_upper)
  {
  	if (found_lower < sub->seq.lower)
  		found_lower = sub->seq.lower;
  	if (found_upper > sub->seq.upper)
  		found_upper = sub->seq.upper;
  	if (found_lower > found_upper)
  		return 0;
  	return 1;
  }
  
  /**
   * tipc_subscr_report_overlap - issue event if there is subscription overlap
   *
   * Protected by nameseq.lock in name_table.c
   */
  void tipc_subscr_report_overlap(struct tipc_subscription *sub, u32 found_lower,
  				u32 found_upper, u32 event, u32 port_ref,
  				u32 node, int must)
  {
  	if (!tipc_subscr_overlap(sub, found_lower, found_upper))
  		return;
  	if (!must && !(sub->filter & TIPC_SUB_PORTS))
  		return;
  
  	subscr_send_event(sub, found_lower, found_upper, event, port_ref, node);
  }
  
  static void subscr_timeout(struct tipc_subscription *sub)
  {
  	struct tipc_subscriber *subscriber = sub->subscriber;
  
  	/* The spin lock per subscriber is used to protect its members */
  	spin_lock_bh(&subscriber->lock);
  
  	/* Validate timeout (in case subscription is being cancelled) */
  	if (sub->timeout == TIPC_WAIT_FOREVER) {
  		spin_unlock_bh(&subscriber->lock);
  		return;
  	}
  
  	/* Unlink subscription from name table */
  	tipc_nametbl_unsubscribe(sub);
  
  	/* Unlink subscription from subscriber */
  	list_del(&sub->subscription_list);
  
  	spin_unlock_bh(&subscriber->lock);
  
  	/* Notify subscriber of timeout */
  	subscr_send_event(sub, sub->evt.s.seq.lower, sub->evt.s.seq.upper,
  			  TIPC_SUBSCR_TIMEOUT, 0, 0);
  
  	/* Now destroy subscription */
  	k_term_timer(&sub->timer);
  	kfree(sub);
  	atomic_dec(&subscription_count);
  }
  
  /**
   * subscr_del - delete a subscription within a subscription list
   *
   * Called with subscriber lock held.
   */
  static void subscr_del(struct tipc_subscription *sub)
  {
  	tipc_nametbl_unsubscribe(sub);
  	list_del(&sub->subscription_list);
  	kfree(sub);
  	atomic_dec(&subscription_count);
  }
  
  /**
   * subscr_terminate - terminate communication with a subscriber
   *
   * Note: Must call it in process context since it might sleep.
   */
  static void subscr_terminate(struct tipc_subscriber *subscriber)
  {
  	tipc_conn_terminate(&topsrv, subscriber->conid);
  }
  
  static void subscr_release(struct tipc_subscriber *subscriber)
  {
  	struct tipc_subscription *sub;
  	struct tipc_subscription *sub_temp;
  
  	spin_lock_bh(&subscriber->lock);
  
  	/* Destroy any existing subscriptions for subscriber */
  	list_for_each_entry_safe(sub, sub_temp, &subscriber->subscription_list,
  				 subscription_list) {
  		if (sub->timeout != TIPC_WAIT_FOREVER) {
  			spin_unlock_bh(&subscriber->lock);
  			k_cancel_timer(&sub->timer);
  			k_term_timer(&sub->timer);
  			spin_lock_bh(&subscriber->lock);
  		}
  		subscr_del(sub);
  	}
  	spin_unlock_bh(&subscriber->lock);
  
  	/* Now destroy subscriber */
  	kfree(subscriber);
  }
  
  /**
   * subscr_cancel - handle subscription cancellation request
   *
   * Called with subscriber lock held. Routine must temporarily release lock
   * to enable the subscription timeout routine to finish without deadlocking;
   * the lock is then reclaimed to allow caller to release it upon return.
   *
   * Note that fields of 's' use subscriber's endianness!
   */
  static void subscr_cancel(struct tipc_subscr *s,
  			  struct tipc_subscriber *subscriber)
  {
  	struct tipc_subscription *sub;
  	struct tipc_subscription *sub_temp;
  	int found = 0;
  
  	/* Find first matching subscription, exit if not found */
  	list_for_each_entry_safe(sub, sub_temp, &subscriber->subscription_list,
  				 subscription_list) {
  		if (!memcmp(s, &sub->evt.s, sizeof(struct tipc_subscr))) {
  			found = 1;
  			break;
  		}
  	}
  	if (!found)
  		return;
  
  	/* Cancel subscription timer (if used), then delete subscription */
  	if (sub->timeout != TIPC_WAIT_FOREVER) {
  		sub->timeout = TIPC_WAIT_FOREVER;
  		spin_unlock_bh(&subscriber->lock);
  		k_cancel_timer(&sub->timer);
  		k_term_timer(&sub->timer);
  		spin_lock_bh(&subscriber->lock);
  	}
  	subscr_del(sub);
  }
  
  /**
   * subscr_subscribe - create subscription for subscriber
   *
   * Called with subscriber lock held.
   */
  static int subscr_subscribe(struct tipc_subscr *s,
  			    struct tipc_subscriber *subscriber,
  			    struct tipc_subscription **sub_p) {
  	struct tipc_subscription *sub;
  	int swap;
  
  	/* Determine subscriber's endianness */
  	swap = !(s->filter & (TIPC_SUB_PORTS | TIPC_SUB_SERVICE));
  
  	/* Detect & process a subscription cancellation request */
  	if (s->filter & htohl(TIPC_SUB_CANCEL, swap)) {
  		s->filter &= ~htohl(TIPC_SUB_CANCEL, swap);
  		subscr_cancel(s, subscriber);
  		return 0;
  	}
  
  	/* Refuse subscription if global limit exceeded */
  	if (atomic_read(&subscription_count) >= TIPC_MAX_SUBSCRIPTIONS) {
  		pr_warn("Subscription rejected, limit reached (%u)
  ",
  			TIPC_MAX_SUBSCRIPTIONS);
  		return -EINVAL;
  	}
  
  	/* Allocate subscription object */
  	sub = kmalloc(sizeof(*sub), GFP_ATOMIC);
  	if (!sub) {
  		pr_warn("Subscription rejected, no memory
  ");
  		return -ENOMEM;
  	}
  
  	/* Initialize subscription object */
  	sub->seq.type = htohl(s->seq.type, swap);
  	sub->seq.lower = htohl(s->seq.lower, swap);
  	sub->seq.upper = htohl(s->seq.upper, swap);
  	sub->timeout = htohl(s->timeout, swap);
  	sub->filter = htohl(s->filter, swap);
  	if ((!(sub->filter & TIPC_SUB_PORTS) ==
  	     !(sub->filter & TIPC_SUB_SERVICE)) ||
  	    (sub->seq.lower > sub->seq.upper)) {
  		pr_warn("Subscription rejected, illegal request
  ");
  		kfree(sub);
  		return -EINVAL;
  	}
  	INIT_LIST_HEAD(&sub->nameseq_list);
  	list_add(&sub->subscription_list, &subscriber->subscription_list);
  	sub->subscriber = subscriber;
  	sub->swap = swap;
  	memcpy(&sub->evt.s, s, sizeof(struct tipc_subscr));
  	atomic_inc(&subscription_count);
  	if (sub->timeout != TIPC_WAIT_FOREVER) {
  		k_init_timer(&sub->timer,
  			     (Handler)subscr_timeout, (unsigned long)sub);
  		k_start_timer(&sub->timer, sub->timeout);
  	}
  	*sub_p = sub;
  	return 0;
  }
  
  /* Handle one termination request for the subscriber */
  static void subscr_conn_shutdown_event(int conid, void *usr_data)
  {
  	subscr_release((struct tipc_subscriber *)usr_data);
  }
  
  /* Handle one request to create a new subscription for the subscriber */
  static void subscr_conn_msg_event(int conid, struct sockaddr_tipc *addr,
  				  void *usr_data, void *buf, size_t len)
  {
  	struct tipc_subscriber *subscriber = usr_data;
  	struct tipc_subscription *sub = NULL;
  
  	spin_lock_bh(&subscriber->lock);
  	if (subscr_subscribe((struct tipc_subscr *)buf, subscriber, &sub) < 0) {
  		spin_unlock_bh(&subscriber->lock);
  		subscr_terminate(subscriber);
  		return;
  	}
  	if (sub)
  		tipc_nametbl_subscribe(sub);
  	spin_unlock_bh(&subscriber->lock);
  }
  
  
  /* Handle one request to establish a new subscriber */
  static void *subscr_named_msg_event(int conid)
  {
  	struct tipc_subscriber *subscriber;
  
  	/* Create subscriber object */
  	subscriber = kzalloc(sizeof(struct tipc_subscriber), GFP_ATOMIC);
  	if (subscriber == NULL) {
  		pr_warn("Subscriber rejected, no memory
  ");
  		return NULL;
  	}
  	INIT_LIST_HEAD(&subscriber->subscription_list);
  	subscriber->conid = conid;
  	spin_lock_init(&subscriber->lock);
  
  	return (void *)subscriber;
  }
  
  int tipc_subscr_start(void)
  {
  	return tipc_server_start(&topsrv);
  }
  
  void tipc_subscr_stop(void)
  {
  	tipc_server_stop(&topsrv);
  }