/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright (c) 2008 Isilon Inc http://www.isilon.com/
 * Authors: Doug Rabson <dfr@rabson.org>
 * Developed with Red Inc: Alfred Perlstein <alfred@freebsd.org>
 *
 * 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.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 AUTHOR 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 <sys/param.h>
#include <sys/hash.h>
#include <sys/kernel.h>
#include <sys/lock.h>
#include <sys/malloc.h>
#include <sys/mbuf.h>
#include <sys/mutex.h>
#include <sys/queue.h>

#include <rpc/rpc.h>
#include <rpc/replay.h>

struct replay_cache_entry {
        int             rce_hash;
        struct rpc_msg  rce_msg;
        struct sockaddr_storage rce_addr;
        struct rpc_msg  rce_repmsg;
        struct mbuf     *rce_repbody;

        TAILQ_ENTRY(replay_cache_entry) rce_link;
        TAILQ_ENTRY(replay_cache_entry) rce_alllink;
};
TAILQ_HEAD(replay_cache_list, replay_cache_entry);

static struct replay_cache_entry *
                replay_alloc(struct replay_cache *rc, struct rpc_msg *msg,
                    struct sockaddr *addr, int h);
static void     replay_free(struct replay_cache *rc,
    struct replay_cache_entry *rce);
static void     replay_prune(struct replay_cache *rc);

#define REPLAY_HASH_SIZE        256
#define REPLAY_MAX              1024

struct replay_cache {
        struct replay_cache_list        rc_cache[REPLAY_HASH_SIZE];
        struct replay_cache_list        rc_all;
        struct mtx                      rc_lock;
        int                             rc_count;
        size_t                          rc_size;
        size_t                          rc_maxsize;
};

struct replay_cache *
replay_newcache(size_t maxsize)
{
        struct replay_cache *rc;
        int i;

        rc = malloc(sizeof(*rc), M_RPC, M_WAITOK|M_ZERO);
        for (i = 0; i < REPLAY_HASH_SIZE; i++)
                TAILQ_INIT(&rc->rc_cache[i]);
        TAILQ_INIT(&rc->rc_all);
        mtx_init(&rc->rc_lock, "rc_lock", NULL, MTX_DEF);
        rc->rc_maxsize = maxsize;

        return (rc);
}

void
replay_setsize(struct replay_cache *rc, size_t newmaxsize)
{

        mtx_lock(&rc->rc_lock);
        rc->rc_maxsize = newmaxsize;
        replay_prune(rc);
        mtx_unlock(&rc->rc_lock);
}

void
replay_freecache(struct replay_cache *rc)
{

        mtx_lock(&rc->rc_lock);
        while (TAILQ_FIRST(&rc->rc_all))
                replay_free(rc, TAILQ_FIRST(&rc->rc_all));
        mtx_destroy(&rc->rc_lock);
        free(rc, M_RPC);
}

static struct replay_cache_entry *
replay_alloc(struct replay_cache *rc,
    struct rpc_msg *msg, struct sockaddr *addr, int h)
{
        struct replay_cache_entry *rce;

        mtx_assert(&rc->rc_lock, MA_OWNED);

        rc->rc_count++;
        rce = malloc(sizeof(*rce), M_RPC, M_NOWAIT|M_ZERO);
        if (!rce)
                return (NULL);
        rce->rce_hash = h;
        rce->rce_msg = *msg;
        bcopy(addr, &rce->rce_addr, addr->sa_len);

        TAILQ_INSERT_HEAD(&rc->rc_cache[h], rce, rce_link);
        TAILQ_INSERT_HEAD(&rc->rc_all, rce, rce_alllink);

        return (rce);
}

static void
replay_free(struct replay_cache *rc, struct replay_cache_entry *rce)
{

        mtx_assert(&rc->rc_lock, MA_OWNED);

        rc->rc_count--;
        TAILQ_REMOVE(&rc->rc_cache[rce->rce_hash], rce, rce_link);
        TAILQ_REMOVE(&rc->rc_all, rce, rce_alllink);
        if (rce->rce_repbody) {
                rc->rc_size -= m_length(rce->rce_repbody, NULL);
                m_freem(rce->rce_repbody);
        }
        free(rce, M_RPC);
}

static void
replay_prune(struct replay_cache *rc)
{
        struct replay_cache_entry *rce;

        mtx_assert(&rc->rc_lock, MA_OWNED);

        if (rc->rc_count < REPLAY_MAX && rc->rc_size <= rc->rc_maxsize)
                return;

        do {
                /*
                 * Try to free an entry. Don't free in-progress entries.
                 */
                TAILQ_FOREACH_REVERSE(rce, &rc->rc_all, replay_cache_list,
                    rce_alllink) {
                        if (rce->rce_repmsg.rm_xid)
                                break;
                }
                if (rce)
                        replay_free(rc, rce);
        } while (rce && (rc->rc_count >= REPLAY_MAX
            || rc->rc_size > rc->rc_maxsize));
}

enum replay_state
replay_find(struct replay_cache *rc, struct rpc_msg *msg,
    struct sockaddr *addr, struct rpc_msg *repmsg, struct mbuf **mp)
{
        int h = HASHSTEP(HASHINIT, msg->rm_xid) % REPLAY_HASH_SIZE;
        struct replay_cache_entry *rce;

        mtx_lock(&rc->rc_lock);
        TAILQ_FOREACH(rce, &rc->rc_cache[h], rce_link) {
                if (rce->rce_msg.rm_xid == msg->rm_xid
                    && rce->rce_msg.rm_call.cb_prog == msg->rm_call.cb_prog     
                    && rce->rce_msg.rm_call.cb_vers == msg->rm_call.cb_vers
                    && rce->rce_msg.rm_call.cb_proc == msg->rm_call.cb_proc
                    && rce->rce_addr.ss_len == addr->sa_len
                    && bcmp(&rce->rce_addr, addr, addr->sa_len) == 0) {
                        if (rce->rce_repmsg.rm_xid) {
                                /*
                                 * We have a reply for this
                                 * message. Copy it and return. Keep
                                 * replay_all LRU sorted
                                 */
                                TAILQ_REMOVE(&rc->rc_all, rce, rce_alllink);
                                TAILQ_INSERT_HEAD(&rc->rc_all, rce,
                                    rce_alllink);
                                *repmsg = rce->rce_repmsg;
                                if (rce->rce_repbody) {
                                        *mp = m_copym(rce->rce_repbody,
                                            0, M_COPYALL, M_NOWAIT);
                                        mtx_unlock(&rc->rc_lock);
                                        if (!*mp)
                                                return (RS_ERROR);
                                } else {
                                        mtx_unlock(&rc->rc_lock);
                                }
                                return (RS_DONE);
                        } else {
                                mtx_unlock(&rc->rc_lock);
                                return (RS_INPROGRESS);
                        }
                }
        }

        replay_prune(rc);

        rce = replay_alloc(rc, msg, addr, h);

        mtx_unlock(&rc->rc_lock);

        if (!rce)
                return (RS_ERROR);
        else
                return (RS_NEW);
}

void
replay_setreply(struct replay_cache *rc,
    struct rpc_msg *repmsg, struct sockaddr *addr, struct mbuf *m)
{
        int h = HASHSTEP(HASHINIT, repmsg->rm_xid) % REPLAY_HASH_SIZE;
        struct replay_cache_entry *rce;

        /*
         * Copy the reply before the lock so we can sleep.
         */
        if (m)
                m = m_copym(m, 0, M_COPYALL, M_WAITOK);

        mtx_lock(&rc->rc_lock);
        TAILQ_FOREACH(rce, &rc->rc_cache[h], rce_link) {
                if (rce->rce_msg.rm_xid == repmsg->rm_xid
                    && rce->rce_addr.ss_len == addr->sa_len
                    && bcmp(&rce->rce_addr, addr, addr->sa_len) == 0) {
                        break;
                }
        }
        if (rce) {
                rce->rce_repmsg = *repmsg;
                rce->rce_repbody = m;
                if (m)
                        rc->rc_size += m_length(m, NULL);
        }
        mtx_unlock(&rc->rc_lock);
}