openvswitch/lib/conntrack.h

/*
 * Copyright (c) 2015, 2016 Nicira, Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at:
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#ifndef CONNTRACK_H
#define CONNTRACK_H 1

#include <stdbool.h>

#include "odp-netlink.h"
#include "openvswitch/hmap.h"
#include "openvswitch/thread.h"
#include "openvswitch/types.h"
#include "ovs-atomic.h"

/* Userspace connection tracker
 * ============================
 *
 * This is a connection tracking module that keeps all the state in userspace.
 *
 * Usage
 * =====
 *
 *     struct conntrack ct;
 *
 * Initialization:
 *
 *     conntrack_init(&ct);
 *
 * It is necessary to periodically issue a call to
 *
 *     conntrack_run(&ct);
 *
 * to allow the module to clean up expired connections.
 *
 * To send a group of packets through the connection tracker:
 *
 *     conntrack_execute(&ct, pkts, n_pkts, ...);
 *
 * Thread-safety
 * =============
 *
 * conntrack_execute() can be called by multiple threads simultaneoulsy.
 */

struct dp_packet_batch;

struct conntrack;

void conntrack_init(struct conntrack *);
void conntrack_run(struct conntrack *);
void conntrack_destroy(struct conntrack *);

int conntrack_execute(struct conntrack *, struct dp_packet_batch *,
                      bool commit, uint16_t zone, const uint32_t *setmark,
                      const struct ovs_key_ct_labels *setlabel,
                      const char *helper);

/* 'struct ct_lock' is a wrapper for an adaptive mutex.  It's useful to try
 * different types of locks (e.g. spinlocks) */

struct OVS_LOCKABLE ct_lock {
    struct ovs_mutex lock;
};

static inline void ct_lock_init(struct ct_lock *lock)
{
    ovs_mutex_init_adaptive(&lock->lock);
}

static inline void ct_lock_lock(struct ct_lock *lock)
    OVS_ACQUIRES(lock)
    OVS_NO_THREAD_SAFETY_ANALYSIS
{
    ovs_mutex_lock(&lock->lock);
}

static inline void ct_lock_unlock(struct ct_lock *lock)
    OVS_RELEASES(lock)
    OVS_NO_THREAD_SAFETY_ANALYSIS
{
    ovs_mutex_unlock(&lock->lock);
}

static inline void ct_lock_destroy(struct ct_lock *lock)
{
    ovs_mutex_destroy(&lock->lock);
}

/* Timeouts: all the possible timeout states passed to update_expiration()
 * are listed here. The name will be prefix by CT_TM_ and the value is in
 * milliseconds */
#define CT_TIMEOUTS \
    CT_TIMEOUT(TCP_FIRST_PACKET, 30 * 1000) \
    CT_TIMEOUT(TCP_OPENING, 30 * 1000) \
    CT_TIMEOUT(TCP_ESTABLISHED, 24 * 60 * 60 * 1000) \
    CT_TIMEOUT(TCP_CLOSING, 15 * 60 * 1000) \
    CT_TIMEOUT(TCP_FIN_WAIT, 45 * 1000) \
    CT_TIMEOUT(TCP_CLOSED, 30 * 1000) \
    CT_TIMEOUT(OTHER_FIRST, 60 * 1000) \
    CT_TIMEOUT(OTHER_MULTIPLE, 60 * 1000) \
    CT_TIMEOUT(OTHER_BIDIR, 30 * 1000) \

enum ct_timeout {
#define CT_TIMEOUT(NAME, VALUE) CT_TM_##NAME,
    CT_TIMEOUTS
#undef CT_TIMEOUT
    N_CT_TM
};

/* Locking:
 *
 * The connections are kept in different buckets, which are completely
 * independent. The connection bucket is determined by the hash of its key.
 * */
struct conntrack_bucket {
    struct ct_lock lock;
    struct hmap connections OVS_GUARDED;
};

#define CONNTRACK_BUCKETS_SHIFT 8
#define CONNTRACK_BUCKETS (1 << CONNTRACK_BUCKETS_SHIFT)

struct conntrack {
    /* Independent buckets containing the connections */
    struct conntrack_bucket buckets[CONNTRACK_BUCKETS];

    /* Salt for hashing a connection key. */
    uint32_t hash_basis;

    /* Number of connections currently in the connection tracker. */
    atomic_count n_conn;
    /* Connections limit. When this limit is reached, no new connection
     * will be accepted. */
    atomic_uint n_conn_limit;
};

#endif /* conntrack.h */