/*
 * 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: controll 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;
        int ret;

        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);
        ret = tipc_conn_sendmsg(&topsrv, subscriber->conid, NULL,
                                msg_sect.iov_base, msg_sect.iov_len);
        if (ret < 0)
                pr_err("Sending subscription event failed, no memory\n");
}

/**
 * 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 if the connection related to the subscriber is
         * closed (in case subscriber is terminating)
         */
        if (subscriber->conid == 0) {
                spin_unlock_bh(&subscriber->lock);
                return;
        }

        /* 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);

        /* Invalidate subscriber reference */
        subscriber->conid = 0;

        /* 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 struct tipc_subscription *subscr_subscribe(struct tipc_subscr *s,
                                             struct tipc_subscriber *subscriber)
{
        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 NULL;
        }

        /* Refuse subscription if global limit exceeded */
        if (atomic_read(&subscription_count) >= TIPC_MAX_SUBSCRIPTIONS) {
                pr_warn("Subscription rejected, limit reached (%u)\n",
                        TIPC_MAX_SUBSCRIPTIONS);
                subscr_terminate(subscriber);
                return NULL;
        }

        /* Allocate subscription object */
        sub = kmalloc(sizeof(*sub), GFP_ATOMIC);
        if (!sub) {
                pr_warn("Subscription rejected, no memory\n");
                subscr_terminate(subscriber);
                return NULL;
        }

        /* 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\n");
                kfree(sub);
                subscr_terminate(subscriber);
                return NULL;
        }
        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);
        }

        return sub;
}

/* 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;

        spin_lock_bh(&subscriber->lock);
        sub = subscr_subscribe((struct tipc_subscr *)buf, subscriber);
        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\n");
                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);
}