subscr.c

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/*
 * net/tipc/subscr.c: TIPC network topology service
 *
 * Copyright (c) 2000-2006, Ericsson AB
 * Copyright (c) 2005-2007, 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 "name_table.h"
#include "port.h"
#include "subscr.h"

struct tipc_subscriber {
    u32 port_ref;
    spinlock_t *lock;
    struct list_head subscriber_list;
    struct list_head subscription_list;
};

struct top_srv {
    u32 setup_port;
    atomic_t subscription_count;
    struct list_head subscriber_list;
    spinlock_t lock;
};

static struct top_srv topsrv;

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 iovec 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_send(sub->server_ref, 1, &msg_sect, msg_sect.iov_len);
}

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;
}

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_port *server_port;

    /* Validate server port reference (in case subscriber is terminating) */
    server_port = tipc_port_lock(sub->server_ref);
    if (server_port == NULL)
        return;

    /* Validate timeout (in case subscription is being cancelled) */
    if (sub->timeout == TIPC_WAIT_FOREVER) {
        tipc_port_unlock(server_port);
        return;
    }

    /* Unlink subscription from name table */
    tipc_nametbl_unsubscribe(sub);

    /* Unlink subscription from subscriber */
    list_del(&sub->subscription_list);

    /* Release subscriber's server port */
    tipc_port_unlock(server_port);

    /* 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(&topsrv.subscription_count);
}

static void subscr_del(struct tipc_subscription *sub)
{
    tipc_nametbl_unsubscribe(sub);
    list_del(&sub->subscription_list);
    kfree(sub);
    atomic_dec(&topsrv.subscription_count);
}

static void subscr_terminate(struct tipc_subscriber *subscriber)
{
    u32 port_ref;
    struct tipc_subscription *sub;
    struct tipc_subscription *sub_temp;

    /* Invalidate subscriber reference */
    port_ref = subscriber->port_ref;
    subscriber->port_ref = 0;
    spin_unlock_bh(subscriber->lock);

    /* Sever connection to subscriber */
    tipc_shutdown(port_ref);
    tipc_deleteport(port_ref);

    /* 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) {
            k_cancel_timer(&sub->timer);
            k_term_timer(&sub->timer);
        }
        subscr_del(sub);
    }

    /* Remove subscriber from topology server's subscriber list */
    spin_lock_bh(&topsrv.lock);
    list_del(&subscriber->subscriber_list);
    spin_unlock_bh(&topsrv.lock);

    /* Reclaim subscriber lock */
    spin_lock_bh(subscriber->lock);

    /* Now destroy subscriber */
    kfree(subscriber);
}

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);
}

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(&topsrv.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->server_ref = subscriber->port_ref;
    sub->swap = swap;
    memcpy(&sub->evt.s, s, sizeof(struct tipc_subscr));
    atomic_inc(&topsrv.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;
}

static void subscr_conn_shutdown_event(void *usr_handle,
                       u32 port_ref,
                       struct sk_buff **buf,
                       unsigned char const *data,
                       unsigned int size,
                       int reason)
{
    struct tipc_subscriber *subscriber = usr_handle;
    spinlock_t *subscriber_lock;

    if (tipc_port_lock(port_ref) == NULL)
        return;

    subscriber_lock = subscriber->lock;
    subscr_terminate(subscriber);
    spin_unlock_bh(subscriber_lock);
}

static void subscr_conn_msg_event(void *usr_handle,
                  u32 port_ref,
                  struct sk_buff **buf,
                  const unchar *data,
                  u32 size)
{
    struct tipc_subscriber *subscriber = usr_handle;
    spinlock_t *subscriber_lock;
    struct tipc_subscription *sub;

    /*
     * Lock subscriber's server port (& make a local copy of lock pointer,
     * in case subscriber is deleted while processing subscription request)
     */
    if (tipc_port_lock(port_ref) == NULL)
        return;

    subscriber_lock = subscriber->lock;

    if (size != sizeof(struct tipc_subscr)) {
        subscr_terminate(subscriber);
        spin_unlock_bh(subscriber_lock);
    } else {
        sub = subscr_subscribe((struct tipc_subscr *)data, subscriber);
        spin_unlock_bh(subscriber_lock);
        if (sub != NULL) {

            /*
             * We must release the server port lock before adding a
             * subscription to the name table since TIPC needs to be
             * able to (re)acquire the port lock if an event message
             * issued by the subscription process is rejected and
             * returned.  The subscription cannot be deleted while
             * it is being added to the name table because:
             * a) the single-threading of the native API port code
             *    ensures the subscription cannot be cancelled and
             *    the subscriber connection cannot be broken, and
             * b) the name table lock ensures the subscription
             *    timeout code cannot delete the subscription,
             * so the subscription object is still protected.
             */
            tipc_nametbl_subscribe(sub);
        }
    }
}

static void subscr_named_msg_event(void *usr_handle,
                   u32 port_ref,
                   struct sk_buff **buf,
                   const unchar *data,
                   u32 size,
                   u32 importance,
                   struct tipc_portid const *orig,
                   struct tipc_name_seq const *dest)
{
    struct tipc_subscriber *subscriber;
    u32 server_port_ref;

    /* Create subscriber object */
    subscriber = kzalloc(sizeof(struct tipc_subscriber), GFP_ATOMIC);
    if (subscriber == NULL) {
        pr_warn("Subscriber rejected, no memory\n");
        return;
    }
    INIT_LIST_HEAD(&subscriber->subscription_list);
    INIT_LIST_HEAD(&subscriber->subscriber_list);

    /* Create server port & establish connection to subscriber */
    tipc_createport(subscriber,
            importance,
            NULL,
            NULL,
            subscr_conn_shutdown_event,
            NULL,
            NULL,
            subscr_conn_msg_event,
            NULL,
            &subscriber->port_ref);
    if (subscriber->port_ref == 0) {
        pr_warn("Subscriber rejected, unable to create port\n");
        kfree(subscriber);
        return;
    }
    tipc_connect2port(subscriber->port_ref, orig);

    /* Lock server port (& save lock address for future use) */
    subscriber->lock = tipc_port_lock(subscriber->port_ref)->lock;

    /* Add subscriber to topology server's subscriber list */
    spin_lock_bh(&topsrv.lock);
    list_add(&subscriber->subscriber_list, &topsrv.subscriber_list);
    spin_unlock_bh(&topsrv.lock);

    /* Unlock server port */
    server_port_ref = subscriber->port_ref;
    spin_unlock_bh(subscriber->lock);

    /* Send an ACK- to complete connection handshaking */
    tipc_send(server_port_ref, 0, NULL, 0);

    /* Handle optional subscription request */
    if (size != 0) {
        subscr_conn_msg_event(subscriber, server_port_ref,
                      buf, data, size);
    }
}

int tipc_subscr_start(void)
{
    struct tipc_name_seq seq = {TIPC_TOP_SRV, TIPC_TOP_SRV, TIPC_TOP_SRV};
    int res;

    spin_lock_init(&topsrv.lock);
    INIT_LIST_HEAD(&topsrv.subscriber_list);

    res = tipc_createport(NULL,
                  TIPC_CRITICAL_IMPORTANCE,
                  NULL,
                  NULL,
                  NULL,
                  NULL,
                  subscr_named_msg_event,
                  NULL,
                  NULL,
                  &topsrv.setup_port);
    if (res)
        goto failed;

    res = tipc_publish(topsrv.setup_port, TIPC_NODE_SCOPE, &seq);
    if (res) {
        tipc_deleteport(topsrv.setup_port);
        topsrv.setup_port = 0;
        goto failed;
    }

    return 0;

failed:
    pr_err("Failed to create subscription service\n");
    return res;
}

void tipc_subscr_stop(void)
{
    struct tipc_subscriber *subscriber;
    struct tipc_subscriber *subscriber_temp;
    spinlock_t *subscriber_lock;

    if (topsrv.setup_port) {
        tipc_deleteport(topsrv.setup_port);
        topsrv.setup_port = 0;

        list_for_each_entry_safe(subscriber, subscriber_temp,
                     &topsrv.subscriber_list,
                     subscriber_list) {
            subscriber_lock = subscriber->lock;
            spin_lock_bh(subscriber_lock);
            subscr_terminate(subscriber);
            spin_unlock_bh(subscriber_lock);
        }
    }
}