/* Copyright (C) 2007-2022 Open Information Security Foundation
 *
 * You can copy, redistribute or modify this Program under the terms of
 * the GNU General Public License version 2 as published by the Free
 * Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * version 2 along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
 * 02110-1301, USA.
 */

/**
 * \file
 *
 * \author Victor Julien <victor@inliniac.net>
 *
 * Packetpool queue handlers. Packet pool is implemented as a stack.
 */

#include "suricata-common.h"
#include "tmqh-packetpool.h"
#include "tm-queuehandlers.h"
#include "tm-threads.h"
#include "threads.h"
#include "decode.h"
#include "tm-modules.h"
#include "packet.h"
#include "util-profiling.h"
#include "util-validate.h"
#include "action-globals.h"

/* Number of freed packet to save for one pool before freeing them. */
#define MAX_PENDING_RETURN_PACKETS 32
static uint32_t max_pending_return_packets = MAX_PENDING_RETURN_PACKETS;

thread_local PktPool thread_pkt_pool;

static inline PktPool *GetThreadPacketPool(void)
{
    return &thread_pkt_pool;
}

/**
 * \brief TmqhPacketpoolRegister
 * \initonly
 */
void TmqhPacketpoolRegister (void)
{
    tmqh_table[TMQH_PACKETPOOL].name = "packetpool";
    tmqh_table[TMQH_PACKETPOOL].InHandler = TmqhInputPacketpool;
    tmqh_table[TMQH_PACKETPOOL].OutHandler = TmqhOutputPacketpool;
}

static int PacketPoolIsEmpty(PktPool *pool)
{
    /* Check local stack first. */
    if (pool->head || pool->return_stack.head)
        return 0;

    return 1;
}

void PacketPoolWait(void)
{
    PktPool *my_pool = GetThreadPacketPool();

    if (PacketPoolIsEmpty(my_pool)) {
        SCMutexLock(&my_pool->return_stack.mutex);
        SC_ATOMIC_ADD(my_pool->return_stack.sync_now, 1);
        SCCondWait(&my_pool->return_stack.cond, &my_pool->return_stack.mutex);
        SCMutexUnlock(&my_pool->return_stack.mutex);
    }

    while(PacketPoolIsEmpty(my_pool))
        cc_barrier();
}

/** \brief Wait until we have the requested amount of packets in the pool
 *
 *  In some cases waiting for packets is undesirable. Especially when
 *  a wait would happen under a lock of some kind, other parts of the
 *  engine could have to wait.
 *
 *  This function only returns when at least N packets are in our pool.
 *
 *  If counting in our pool's main stack didn't give us the number we
 *  are seeking, we check if the return stack is filled and add those
 *  to our main stack. Then we retry.
 *
 *  \param n number of packets needed
 */
void PacketPoolWaitForN(int n)
{
    PktPool *my_pool = GetThreadPacketPool();

    while (1) {
        PacketPoolWait();

        /* count packets in our stack */
        int i = 0;
        Packet *p, *pp;
        pp = p = my_pool->head;
        while (p != NULL) {
            if (++i == n)
                return;

            pp = p;
            p = p->next;
        }

        /* check return stack, return to our pool and retry counting */
        if (my_pool->return_stack.head != NULL) {
            SCMutexLock(&my_pool->return_stack.mutex);
            /* Move all the packets from the locked return stack to the local stack. */
            if (pp) {
                pp->next = my_pool->return_stack.head;
            } else {
                my_pool->head = my_pool->return_stack.head;
            }
            my_pool->return_stack.head = NULL;
            SC_ATOMIC_RESET(my_pool->return_stack.sync_now);
            SCMutexUnlock(&my_pool->return_stack.mutex);

        /* or signal that we need packets and wait */
        } else {
            SCMutexLock(&my_pool->return_stack.mutex);
            SC_ATOMIC_ADD(my_pool->return_stack.sync_now, 1);
            SCCondWait(&my_pool->return_stack.cond, &my_pool->return_stack.mutex);
            SCMutexUnlock(&my_pool->return_stack.mutex);
        }
    }
}

/** \brief a initialized packet
 *
 *  \warning Use *only* at init, not at packet runtime
 */
static void PacketPoolStorePacket(Packet *p)
{
    p->pool = GetThreadPacketPool();
    p->ReleasePacket = PacketPoolReturnPacket;
    PacketPoolReturnPacket(p);
}

static void PacketPoolGetReturnedPackets(PktPool *pool)
{
    SCMutexLock(&pool->return_stack.mutex);
    /* Move all the packets from the locked return stack to the local stack. */
    pool->head = pool->return_stack.head;
    pool->return_stack.head = NULL;
    SCMutexUnlock(&pool->return_stack.mutex);
}

/** \brief Get a new packet from the packet pool
 *
 * Only allocates from the thread's local stack, or mallocs new packets.
 * If the local stack is empty, first move all the return stack packets to
 * the local stack.
 *  \retval Packet pointer, or NULL on failure.
 */
Packet *PacketPoolGetPacket(void)
{
    PktPool *pool = GetThreadPacketPool();
#ifdef DEBUG_VALIDATION
    BUG_ON(pool->initialized == 0);
    BUG_ON(pool->destroyed == 1);
#endif /* DEBUG_VALIDATION */
    if (pool->head) {
        /* Stack is not empty. */
        Packet *p = pool->head;
        pool->head = p->next;
        p->pool = pool;
        PacketReinit(p);
        return p;
    }

    /* Local Stack is empty, so check the return stack, which requires
     * locking. */
    PacketPoolGetReturnedPackets(pool);

    /* Try to allocate again. Need to check for not empty again, since the
     * return stack might have been empty too.
     */
    if (pool->head) {
        /* Stack is not empty. */
        Packet *p = pool->head;
        pool->head = p->next;
        p->pool = pool;
        PacketReinit(p);
        return p;
    }

    /* Failed to allocate a packet, so return NULL. */
    /* Optionally, could allocate a new packet here. */
    return NULL;
}

/** \brief Return packet to Packet pool
 *
 */
void PacketPoolReturnPacket(Packet *p)
{
    PktPool *my_pool = GetThreadPacketPool();
    PktPool *pool = p->pool;
    if (pool == NULL) {
        PacketFree(p);
        return;
    }

    PacketReleaseRefs(p);

#ifdef DEBUG_VALIDATION
    BUG_ON(pool->initialized == 0);
    BUG_ON(pool->destroyed == 1);
    BUG_ON(my_pool->initialized == 0);
    BUG_ON(my_pool->destroyed == 1);
#endif /* DEBUG_VALIDATION */

    if (pool == my_pool) {
        /* Push back onto this thread's own stack, so no locking. */
        p->next = my_pool->head;
        my_pool->head = p;
    } else {
        PktPool *pending_pool = my_pool->pending_pool;
        if (pending_pool == NULL) {
            /* No pending packet, so store the current packet. */
            p->next = NULL;
            my_pool->pending_pool = pool;
            my_pool->pending_head = p;
            my_pool->pending_tail = p;
            my_pool->pending_count = 1;
        } else if (pending_pool == pool) {
            /* Another packet for the pending pool list. */
            p->next = my_pool->pending_head;
            my_pool->pending_head = p;
            my_pool->pending_count++;
            if (SC_ATOMIC_GET(pool->return_stack.sync_now) || my_pool->pending_count > max_pending_return_packets) {
                /* Return the entire list of pending packets. */
                SCMutexLock(&pool->return_stack.mutex);
                my_pool->pending_tail->next = pool->return_stack.head;
                pool->return_stack.head = my_pool->pending_head;
                SC_ATOMIC_RESET(pool->return_stack.sync_now);
                SCMutexUnlock(&pool->return_stack.mutex);
                SCCondSignal(&pool->return_stack.cond);
                /* Clear the list of pending packets to return. */
                my_pool->pending_pool = NULL;
                my_pool->pending_head = NULL;
                my_pool->pending_tail = NULL;
                my_pool->pending_count = 0;
            }
        } else {
            /* Push onto return stack for this pool */
            SCMutexLock(&pool->return_stack.mutex);
            p->next = pool->return_stack.head;
            pool->return_stack.head = p;
            SC_ATOMIC_RESET(pool->return_stack.sync_now);
            SCMutexUnlock(&pool->return_stack.mutex);
            SCCondSignal(&pool->return_stack.cond);
        }
    }
}

void PacketPoolInitEmpty(void)
{
    PktPool *my_pool = GetThreadPacketPool();

#ifdef DEBUG_VALIDATION
    BUG_ON(my_pool->initialized);
    my_pool->initialized = 1;
    my_pool->destroyed = 0;
#endif /* DEBUG_VALIDATION */

    SCMutexInit(&my_pool->return_stack.mutex, NULL);
    SCCondInit(&my_pool->return_stack.cond, NULL);
    SC_ATOMIC_INIT(my_pool->return_stack.sync_now);
}

void PacketPoolInit(void)
{
    extern intmax_t max_pending_packets;

    PktPool *my_pool = GetThreadPacketPool();

#ifdef DEBUG_VALIDATION
    BUG_ON(my_pool->initialized);
    my_pool->initialized = 1;
    my_pool->destroyed = 0;
#endif /* DEBUG_VALIDATION */

    SCMutexInit(&my_pool->return_stack.mutex, NULL);
    SCCondInit(&my_pool->return_stack.cond, NULL);
    SC_ATOMIC_INIT(my_pool->return_stack.sync_now);

    /* pre allocate packets */
    SCLogDebug("preallocating packets... packet size %" PRIuMAX "",
               (uintmax_t)SIZE_OF_PACKET);
    int i = 0;
    for (i = 0; i < max_pending_packets; i++) {
        Packet *p = PacketGetFromAlloc();
        if (unlikely(p == NULL)) {
            FatalError("Fatal error encountered while allocating a packet. Exiting...");
        }
        PacketPoolStorePacket(p);
    }

    //SCLogInfo("preallocated %"PRIiMAX" packets. Total memory %"PRIuMAX"",
    //        max_pending_packets, (uintmax_t)(max_pending_packets*SIZE_OF_PACKET));
}

void PacketPoolDestroy(void)
{
    Packet *p = NULL;
    PktPool *my_pool = GetThreadPacketPool();

#ifdef DEBUG_VALIDATION
    BUG_ON(my_pool && my_pool->destroyed);
#endif /* DEBUG_VALIDATION */

    if (my_pool && my_pool->pending_pool != NULL) {
        p = my_pool->pending_head;
        while (p) {
            Packet *next_p = p->next;
            PacketFree(p);
            p = next_p;
            my_pool->pending_count--;
        }
#ifdef DEBUG_VALIDATION
        BUG_ON(my_pool->pending_count);
#endif /* DEBUG_VALIDATION */
        my_pool->pending_pool = NULL;
        my_pool->pending_head = NULL;
        my_pool->pending_tail = NULL;
    }

    while ((p = PacketPoolGetPacket()) != NULL) {
        PacketFree(p);
    }

#ifdef DEBUG_VALIDATION
    my_pool->initialized = 0;
    my_pool->destroyed = 1;
#endif /* DEBUG_VALIDATION */
}

Packet *TmqhInputPacketpool(ThreadVars *tv)
{
    return PacketPoolGetPacket();
}

void TmqhOutputPacketpool(ThreadVars *t, Packet *p)
{
    bool proot = false;

    SCEnter();
    SCLogDebug("Packet %p, p->root %p, alloced %s", p, p->root, BOOL2STR(p->pool == NULL));

    if (IS_TUNNEL_PKT(p)) {
        SCLogDebug("Packet %p is a tunnel packet: %s",
            p,p->root ? "upper layer" : "tunnel root");

        /* get a lock to access root packet fields */
        SCSpinlock *lock = p->root ? &p->root->persistent.tunnel_lock : &p->persistent.tunnel_lock;
        SCSpinLock(lock);

        if (IS_TUNNEL_ROOT_PKT(p)) {
            SCLogDebug("IS_TUNNEL_ROOT_PKT == TRUE");
            const uint16_t outstanding = TUNNEL_PKT_TPR(p) - TUNNEL_PKT_RTV(p);
            SCLogDebug("root pkt: outstanding %u", outstanding);
            if (outstanding == 0) {
                SCLogDebug("no tunnel packets outstanding, no more tunnel "
                        "packet(s) depending on this root");
                /* if this packet is the root and there are no
                 * more tunnel packets to consider
                 *
                 * return it to the pool */
            } else {
                SCLogDebug("tunnel root Packet %p: outstanding > 0, so "
                        "packets are still depending on this root, setting "
                        "SET_TUNNEL_PKT_VERDICTED", p);
                /* if this is the root and there are more tunnel
                 * packets, return this to the pool. It's still referenced
                 * by the tunnel packets, and we will return it
                 * when we handle them */
                SET_TUNNEL_PKT_VERDICTED(p);

                PACKET_PROFILING_END(p);
                SCSpinUnlock(lock);
                SCReturn;
            }
        } else {
            SCLogDebug("NOT IS_TUNNEL_ROOT_PKT, so tunnel pkt");

            TUNNEL_INCR_PKT_RTV_NOLOCK(p);
            const uint16_t outstanding = TUNNEL_PKT_TPR(p) - TUNNEL_PKT_RTV(p);
            SCLogDebug("tunnel pkt: outstanding %u", outstanding);
            /* all tunnel packets are processed except us. Root already
             * processed. So return tunnel pkt and root packet to the
             * pool. */
            if (outstanding == 0 &&
                    p->root && IS_TUNNEL_PKT_VERDICTED(p->root))
            {
                SCLogDebug("root verdicted == true && no outstanding");

                /* handle freeing the root as well*/
                SCLogDebug("setting proot = 1 for root pkt, p->root %p "
                        "(tunnel packet %p)", p->root, p);
                proot = true;

                /* fall through */

            } else {
                /* root not ready yet, or not the last tunnel packet,
                 * so get rid of the tunnel pkt only */

                SCLogDebug("NOT IS_TUNNEL_PKT_VERDICTED (%s) || "
                        "outstanding > 0 (%u)",
                        (p->root && IS_TUNNEL_PKT_VERDICTED(p->root)) ? "true" : "false",
                        outstanding);

                /* fall through */
            }
        }
        SCSpinUnlock(lock);

        SCLogDebug("tunnel stuff done, move on (proot %d)", proot);
    }

    SCLogDebug("[packet %p][%s] %s", p,
            IS_TUNNEL_PKT(p) ? IS_TUNNEL_ROOT_PKT(p) ? "tunnel::root" : "tunnel::leaf"
                             : "no tunnel",
            (p->action & ACTION_DROP) ? "DROP" : "no drop");

    /* we're done with the tunnel root now as well */
    if (proot == true) {
        SCLogDebug("getting rid of root pkt... alloc'd %s", BOOL2STR(p->root->pool == NULL));

        PacketReleaseRefs(p->root);
        p->root->ReleasePacket(p->root);
        p->root = NULL;
    }

    PACKET_PROFILING_END(p);

    PacketReleaseRefs(p);
    p->ReleasePacket(p);

    SCReturn;
}

/**
 *  \brief Release all the packets in the queue back to the packetpool.  Mainly
 *         used by threads that have failed, and wants to return the packets back
 *         to the packetpool.
 *
 *  \param pq Pointer to the packetqueue from which the packets have to be
 *            returned back to the packetpool
 *
 *  \warning this function assumes that the pq does not use locking
 */
void TmqhReleasePacketsToPacketPool(PacketQueue *pq)
{
    Packet *p = NULL;

    if (pq == NULL)
        return;

    while ((p = PacketDequeue(pq)) != NULL) {
        DEBUG_VALIDATE_BUG_ON(p->flow != NULL);
        TmqhOutputPacketpool(NULL, p);
    }

    return;
}

/** number of packets to keep reserved when calculating the the pending
 *  return packets count. This assumes we need at max 10 packets in one
 *  PacketPoolWaitForN call. The actual number is 9 now, so this has a
 *  bit of margin. */
#define RESERVED_PACKETS 10

/**
 *  \brief Set the max_pending_return_packets value
 *
 *  Set it to the max pending packets value, devided by the number
 *  of lister threads. Normally, in autofp these are the stream/detect/log
 *  worker threads.
 *
 *  The max_pending_return_packets value needs to stay below the packet
 *  pool size of the 'producers' (normally pkt capture threads but also
 *  flow timeout injection ) to avoid a deadlock where all the 'workers'
 *  keep packets in their return pools, while the capture thread can't
 *  continue because its pool is empty.
 */
void PacketPoolPostRunmodes(void)
{
    extern intmax_t max_pending_packets;
    intmax_t pending_packets = max_pending_packets;
    if (pending_packets < RESERVED_PACKETS) {
        FatalError("'max-pending-packets' setting "
                   "must be at least %d",
                RESERVED_PACKETS);
    }
    uint32_t threads = TmThreadCountThreadsByTmmFlags(TM_FLAG_DETECT_TM);
    if (threads == 0)
        return;

    uint32_t packets = (pending_packets / threads) - 1;
    if (packets < max_pending_return_packets)
        max_pending_return_packets = packets;

    /* make sure to have a margin in the return logic */
    if (max_pending_return_packets >= RESERVED_PACKETS)
        max_pending_return_packets -= RESERVED_PACKETS;

    SCLogDebug("detect threads %u, max packets %u, max_pending_return_packets %u",
            threads, packets, max_pending_return_packets);
}
