/*
 * 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\n");
                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)\n",
                        TIPC_MAX_SUBSCRIPTIONS);
                return -EINVAL;
        }

        /* Allocate subscription object */
        sub = kmalloc(sizeof(*sub), GFP_ATOMIC);
        if (!sub) {
                pr_warn("Subscription rejected, no memory\n");
                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\n");
                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 *subscriber = usr_data;
        struct tipc_subscription *sub = NULL;
        struct tipc_net *tn = net_generic(net, tipc_net_id);

        tipc_subscrp_create(net, (struct tipc_subscr *)buf, subscriber, &sub);
        if (sub)
                tipc_nametbl_subscribe(sub);
        else
                tipc_conn_terminate(tn->topsrv, subscriber->conid);
}

/* 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);
}