/*
   * 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 "subscr.h"
  
  /**
   * struct tipc_subscriber - TIPC network topology subscriber
   * @kref: reference counter to tipc_subscription object
   * @conid: connection identifier to server connecting to subscriber
   * @lock: control access to subscriber
   * @subscrp_list: list of subscription objects for this subscriber
   */
  struct tipc_subscriber {
  	struct kref kref;
  	int conid;
  	spinlock_t lock;
  	struct list_head subscrp_list;
  };
  
  static void tipc_subscrp_delete(struct tipc_subscription *sub);
  static void tipc_subscrb_put(struct tipc_subscriber *subscriber);
  
  /**
   * 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 tipc_subscrp_send_event(struct tipc_subscription *sub,
  				    u32 found_lower, u32 found_upper,
  				    u32 event, u32 port_ref, u32 node)
  {
  	struct tipc_net *tn = net_generic(sub->net, tipc_net_id);
  	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(tn->topsrv, subscriber->conid, NULL,
  			  msg_sect.iov_base, msg_sect.iov_len);
  }
  
  /**
   * tipc_subscrp_check_overlap - test for subscription overlap with the
   * given values
   *
   * Returns 1 if there is overlap, otherwise 0.
   */
  int tipc_subscrp_check_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;
  }
  
  void tipc_subscrp_report_overlap(struct tipc_subscription *sub, u32 found_lower,
  				 u32 found_upper, u32 event, u32 port_ref,
  				 u32 node, int must)
  {
  	if (!tipc_subscrp_check_overlap(sub, found_lower, found_upper))
  		return;
  	if (!must && !(sub->filter & TIPC_SUB_PORTS))
  		return;
  
  	tipc_subscrp_send_event(sub, found_lower, found_upper, event, port_ref,
  				node);
  }
  
  static void tipc_subscrp_timeout(unsigned long data)
  {
  	struct tipc_subscription *sub = (struct tipc_subscription *)data;
  	struct tipc_subscriber *subscriber = sub->subscriber;
  
  	/* Notify subscriber of timeout */
  	tipc_subscrp_send_event(sub, sub->evt.s.seq.lower, sub->evt.s.seq.upper,
  				TIPC_SUBSCR_TIMEOUT, 0, 0);
  
  	spin_lock_bh(&subscriber->lock);
  	tipc_subscrp_delete(sub);
  	spin_unlock_bh(&subscriber->lock);
  
  	tipc_subscrb_put(subscriber);
  }
  
  static void tipc_subscrb_kref_release(struct kref *kref)
  {
  	struct tipc_subscriber *subcriber = container_of(kref,
  					    struct tipc_subscriber, kref);
  
  	kfree(subcriber);
  }
  
  static void tipc_subscrb_put(struct tipc_subscriber *subscriber)
  {
  	kref_put(&subscriber->kref, tipc_subscrb_kref_release);
  }
  
  static void tipc_subscrb_get(struct tipc_subscriber *subscriber)
  {
  	kref_get(&subscriber->kref);
  }
  
  static struct tipc_subscriber *tipc_subscrb_create(int conid)
  {
  	struct tipc_subscriber *subscriber;
  
  	subscriber = kzalloc(sizeof(*subscriber), GFP_ATOMIC);
  	if (!subscriber) {
  		pr_warn("Subscriber rejected, no memory
  ");
  		return NULL;
  	}
  	kref_init(&subscriber->kref);
  	INIT_LIST_HEAD(&subscriber->subscrp_list);
  	subscriber->conid = conid;
  	spin_lock_init(&subscriber->lock);
  
  	return subscriber;
  }
  
  static void tipc_subscrb_delete(struct tipc_subscriber *subscriber)
  {
  	struct tipc_subscription *sub, *temp;
  
  	spin_lock_bh(&subscriber->lock);
  	/* Destroy any existing subscriptions for subscriber */
  	list_for_each_entry_safe(sub, temp, &subscriber->subscrp_list,
  				 subscrp_list) {
  		if (del_timer(&sub->timer)) {
  			tipc_subscrp_delete(sub);
  			tipc_subscrb_put(subscriber);
  		}
  	}
  	spin_unlock_bh(&subscriber->lock);
  
  	tipc_subscrb_put(subscriber);
  }
  
  static void tipc_subscrp_delete(struct tipc_subscription *sub)
  {
  	struct tipc_net *tn = net_generic(sub->net, tipc_net_id);
  
  	tipc_nametbl_unsubscribe(sub);
  	list_del(&sub->subscrp_list);
  	kfree(sub);
  	atomic_dec(&tn->subscription_count);
  }
  
  static void tipc_subscrp_cancel(struct tipc_subscr *s,
  				struct tipc_subscriber *subscriber)
  {
  	struct tipc_subscription *sub, *temp;
  
  	spin_lock_bh(&subscriber->lock);
  	/* Find first matching subscription, exit if not found */
  	list_for_each_entry_safe(sub, temp, &subscriber->subscrp_list,
  				 subscrp_list) {
  		if (!memcmp(s, &sub->evt.s, sizeof(struct tipc_subscr))) {
  			if (del_timer(&sub->timer)) {
  				tipc_subscrp_delete(sub);
  				tipc_subscrb_put(subscriber);
  			}
  			break;
  		}
  	}
  	spin_unlock_bh(&subscriber->lock);
  }
  
  static int tipc_subscrp_create(struct net *net, struct tipc_subscr *s,
  			       struct tipc_subscriber *subscriber,
  			       struct tipc_subscription **sub_p)
  {
  	struct tipc_net *tn = net_generic(net, tipc_net_id);
  	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);
  		tipc_subscrp_cancel(s, subscriber);
  		return 0;
  	}
  
  	/* Refuse subscription if global limit exceeded */
  	if (atomic_read(&tn->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->net = net;
  	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 = msecs_to_jiffies(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;
  	}
  	spin_lock_bh(&subscriber->lock);
  	list_add(&sub->subscrp_list, &subscriber->subscrp_list);
  	spin_unlock_bh(&subscriber->lock);
  	sub->subscriber = subscriber;
  	sub->swap = swap;
  	memcpy(&sub->evt.s, s, sizeof(*s));
  	atomic_inc(&tn->subscription_count);
  	setup_timer(&sub->timer, tipc_subscrp_timeout, (unsigned long)sub);
  	if (sub->timeout != TIPC_WAIT_FOREVER)
  		sub->timeout += jiffies;
  	if (!mod_timer(&sub->timer, sub->timeout))
  		tipc_subscrb_get(subscriber);
  	*sub_p = sub;
  	return 0;
  }
  
  /* Handle one termination request for the subscriber */
  static void tipc_subscrb_shutdown_cb(int conid, void *usr_data)
  {
  	tipc_subscrb_delete((struct tipc_subscriber *)usr_data);
  }
  
  /* Handle one request to create a new subscription for the subscriber */
  static void tipc_subscrb_rcv_cb(struct net *net, int conid,
  				struct sockaddr_tipc *addr, void *usr_data,
  				void *buf, size_t len)
  {
  	struct tipc_subscriber *subscrb = usr_data;
  	struct tipc_subscription *sub = NULL;
  	struct tipc_net *tn = net_generic(net, tipc_net_id);
  
  	if (tipc_subscrp_create(net, (struct tipc_subscr *)buf, subscrb, &sub))
  		return tipc_conn_terminate(tn->topsrv, subscrb->conid);
  
  	if (sub)
  		tipc_nametbl_subscribe(sub);
  }
  
  /* Handle one request to establish a new subscriber */
  static void *tipc_subscrb_connect_cb(int conid)
  {
  	return (void *)tipc_subscrb_create(conid);
  }
  
  int tipc_topsrv_start(struct net *net)
  {
  	struct tipc_net *tn = net_generic(net, tipc_net_id);
  	const char name[] = "topology_server";
  	struct tipc_server *topsrv;
  	struct sockaddr_tipc *saddr;
  
  	saddr = kzalloc(sizeof(*saddr), GFP_ATOMIC);
  	if (!saddr)
  		return -ENOMEM;
  	saddr->family			= AF_TIPC;
  	saddr->addrtype			= TIPC_ADDR_NAMESEQ;
  	saddr->addr.nameseq.type	= TIPC_TOP_SRV;
  	saddr->addr.nameseq.lower	= TIPC_TOP_SRV;
  	saddr->addr.nameseq.upper	= TIPC_TOP_SRV;
  	saddr->scope			= TIPC_NODE_SCOPE;
  
  	topsrv = kzalloc(sizeof(*topsrv), GFP_ATOMIC);
  	if (!topsrv) {
  		kfree(saddr);
  		return -ENOMEM;
  	}
  	topsrv->net			= net;
  	topsrv->saddr			= saddr;
  	topsrv->imp			= TIPC_CRITICAL_IMPORTANCE;
  	topsrv->type			= SOCK_SEQPACKET;
  	topsrv->max_rcvbuf_size		= sizeof(struct tipc_subscr);
  	topsrv->tipc_conn_recvmsg	= tipc_subscrb_rcv_cb;
  	topsrv->tipc_conn_new		= tipc_subscrb_connect_cb;
  	topsrv->tipc_conn_shutdown	= tipc_subscrb_shutdown_cb;
  
  	strncpy(topsrv->name, name, strlen(name) + 1);
  	tn->topsrv = topsrv;
  	atomic_set(&tn->subscription_count, 0);
  
  	return tipc_server_start(topsrv);
  }
  
  void tipc_topsrv_stop(struct net *net)
  {
  	struct tipc_net *tn = net_generic(net, tipc_net_id);
  	struct tipc_server *topsrv = tn->topsrv;
  
  	tipc_server_stop(topsrv);
  	kfree(topsrv->saddr);
  	kfree(topsrv);
  }