/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */

/*
 * Copyright 2009 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

#include <sys/types.h>
#include <sys/cmn_err.h>
#include <netinet/in.h>
#include <inet/ip.h>
#include <inet/ip6.h>
#include <sys/crc32.h>

#include <inet/ilb.h>
#include "ilb_impl.h"
#include "ilb_alg.h"

#define HASH_IP_V4(hash, addr, size)                                    \
{                                                                       \
        CRC32((hash), &(addr), sizeof (in_addr_t), -1U, crc32_table);   \
        (hash) %= (size);                                               \
}
#define HASH_IP_V6(hash, addr, size)                                    \
        HASH_IP_V4((hash), (addr)->s6_addr32[3], (size))

#define HASH_IP_PORT_V4(hash, addr, port, size)                         \
{                                                                       \
        uint32_t val = (addr) ^ ((port) << 16) ^ (port);                \
        CRC32((hash), &val, sizeof (uint32_t), -1U, crc32_table);       \
        (hash) %= (size);                                               \
}
#define HASH_IP_PORT_V6(hash, addr, port, size)                         \
        HASH_IP_PORT_V4((hash), (addr)->s6_addr32[3], (port), (size))

#define HASH_IP_VIP_V4(hash, saddr, daddr, size)                        \
{                                                                       \
        uint32_t val = (saddr) ^ (daddr);                               \
        CRC32((hash), &val, sizeof (uint32_t), -1U, crc32_table);       \
        (hash) %= (size);                                               \
}
#define HASH_IP_VIP_V6(hash, saddr, daddr, size)                        \
        HASH_IP_VIP_V4((hash), (saddr)->s6_addr32[3], (daddr)->s6_addr32[3], \
        (size))

#define INIT_HASH_TBL_SIZE      10

typedef struct {
        ilb_server_t    *server;
        boolean_t       enabled;
} hash_server_t;

/*
 * There are two hash tables.  The hash_tbl holds all servers, both enabled
 * and disabled.  The hash_enabled_tbl only holds enabled servers.  Having
 * two tables allows the hash on a client request remains the same even when
 * some servers are disabled.  If a server is disabled and a client's request
 * hashes to it, we will do another hash.  This time the has is on the enabled
 * server table.
 */
typedef struct hash_s {
        kmutex_t        hash_lock;
        size_t          hash_servers;           /* Total # of servers */
        size_t          hash_tbl_size;          /* All server table size */
        size_t          hash_enabled_servers;   /* # of enabled servers */
        size_t          hash_enabled_tbl_size;  /* Enabled server table size */
        hash_server_t   *hash_tbl;
        hash_server_t   *hash_enabled_tbl;
        ilb_algo_impl_t hash_type;
} hash_t;

static void hash_fini(ilb_alg_data_t **);

/* ARGSUSED */
static boolean_t
hash_lb(in6_addr_t *saddr, in_port_t sport, in6_addr_t *daddr,
    in_port_t dport, void *alg_data, ilb_server_t **ret_server)
{
        hash_t *hash_alg = (hash_t *)alg_data;
        uint32_t i;

        ASSERT(ret_server != NULL);
        *ret_server = NULL;

        mutex_enter(&hash_alg->hash_lock);

        if (hash_alg->hash_servers == 0) {
                mutex_exit(&hash_alg->hash_lock);
                return (B_FALSE);
        }

        switch (hash_alg->hash_type) {
        case ILB_ALG_IMPL_HASH_IP:
                HASH_IP_V6(i, saddr, hash_alg->hash_servers);
                break;
        case ILB_ALG_IMPL_HASH_IP_SPORT:
                HASH_IP_PORT_V6(i, saddr, sport, hash_alg->hash_servers);
                break;
        case ILB_ALG_IMPL_HASH_IP_VIP:
                HASH_IP_VIP_V6(i, saddr, daddr, hash_alg->hash_servers);
                break;
        default:
                mutex_exit(&hash_alg->hash_lock);
                return (B_FALSE);
        }
        if (hash_alg->hash_tbl[i].enabled) {
                *ret_server = hash_alg->hash_tbl[i].server;
                mutex_exit(&hash_alg->hash_lock);
                return (B_TRUE);
        }

        if (hash_alg->hash_enabled_servers == 0) {
                mutex_exit(&hash_alg->hash_lock);
                return (B_FALSE);
        }

        switch (hash_alg->hash_type) {
        case ILB_ALG_IMPL_HASH_IP:
                HASH_IP_V6(i, saddr, hash_alg->hash_enabled_servers);
                break;
        case ILB_ALG_IMPL_HASH_IP_SPORT:
                HASH_IP_PORT_V6(i, saddr, sport,
                    hash_alg->hash_enabled_servers);
                break;
        case ILB_ALG_IMPL_HASH_IP_VIP:
                HASH_IP_VIP_V6(i, saddr, daddr,
                    hash_alg->hash_enabled_servers);
                break;
        default:
                ASSERT(0);
                break;
        }
        *ret_server = hash_alg->hash_enabled_tbl[i].server;
        mutex_exit(&hash_alg->hash_lock);
        return (B_TRUE);
}

static boolean_t
del_server(hash_server_t *tbl, size_t hash_size, ilb_server_t *host)
{
        size_t i, j;

        for (i = 0; i < hash_size; i++) {
                if (tbl[i].server == host) {
                        if (i == hash_size - 1)
                                break;
                        for (j = i; j < hash_size - 1; j++)
                                tbl[j] = tbl[j + 1];
                        break;
                }
        }
        /* Not found... */
        if (i == hash_size)
                return (B_FALSE);
        tbl[hash_size - 1].server = NULL;
        tbl[hash_size - 1].enabled = B_FALSE;
        return (B_TRUE);
}

static int
hash_server_del(ilb_server_t *host, void *alg_data)
{
        hash_t *hash_alg = (hash_t *)alg_data;
        boolean_t ret;

        mutex_enter(&hash_alg->hash_lock);

        ret = del_server(hash_alg->hash_tbl, hash_alg->hash_servers, host);
        if (!ret) {
                mutex_exit(&hash_alg->hash_lock);
                return (EINVAL);
        }
        hash_alg->hash_servers--;

        /* The server may not be enabled. */
        ret = del_server(hash_alg->hash_enabled_tbl,
            hash_alg->hash_enabled_servers, host);
        if (ret)
                hash_alg->hash_enabled_servers--;

        mutex_exit(&hash_alg->hash_lock);
        ILB_SERVER_REFRELE(host);
        return (0);
}

static int
grow_tbl(hash_server_t **hash_tbl, size_t *tbl_size)
{
        size_t mem_size;
        hash_server_t *new_tbl;

        if ((new_tbl = kmem_zalloc(sizeof (hash_server_t) *
            (*tbl_size + INIT_HASH_TBL_SIZE), KM_NOSLEEP)) == NULL) {
                return (ENOMEM);
        }
        mem_size = *tbl_size * sizeof (hash_server_t);
        bcopy(*hash_tbl, new_tbl, mem_size);
        kmem_free(*hash_tbl, mem_size);
        *hash_tbl = new_tbl;
        *tbl_size += INIT_HASH_TBL_SIZE;
        return (0);
}

static int
hash_server_add(ilb_server_t *host, void *alg_data)
{
        hash_t *hash_alg = (hash_t *)alg_data;
        size_t new_size;

        mutex_enter(&hash_alg->hash_lock);

        /* First add the server to the hash_tbl. */
        new_size = hash_alg->hash_servers + 1;
        if (new_size > hash_alg->hash_tbl_size) {
                if (grow_tbl(&hash_alg->hash_tbl, &hash_alg->hash_tbl_size) !=
                    0) {
                        mutex_exit(&hash_alg->hash_lock);
                        return (ENOMEM);
                }
        }

        hash_alg->hash_tbl[hash_alg->hash_servers].server = host;
        hash_alg->hash_tbl[hash_alg->hash_servers].enabled = host->iser_enabled;
        hash_alg->hash_servers++;

        if (!host->iser_enabled) {
                mutex_exit(&hash_alg->hash_lock);
                ILB_SERVER_REFHOLD(host);
                return (0);
        }

        /* If the server is enabled, add it to the hasn_enabled_tbl. */
        new_size = hash_alg->hash_enabled_servers + 1;
        if (new_size > hash_alg->hash_enabled_tbl_size) {
                if (grow_tbl(&hash_alg->hash_enabled_tbl,
                    &hash_alg->hash_enabled_tbl_size) != 0) {
                        mutex_exit(&hash_alg->hash_lock);
                        return (ENOMEM);
                }
        }
        hash_alg->hash_enabled_tbl[hash_alg->hash_enabled_servers].server =
            host;
        hash_alg->hash_enabled_tbl[hash_alg->hash_enabled_servers].enabled =
            B_TRUE;
        hash_alg->hash_enabled_servers++;

        mutex_exit(&hash_alg->hash_lock);
        ILB_SERVER_REFHOLD(host);
        return (0);
}

static int
hash_server_enable(ilb_server_t *host, void *alg_data)
{
        hash_t *alg = (hash_t *)alg_data;
        size_t new_size, i;

        mutex_enter(&alg->hash_lock);

        for (i = 0; i < alg->hash_servers; i++) {
                if (alg->hash_tbl[i].server == host) {
                        if (alg->hash_tbl[i].enabled) {
                                mutex_exit(&alg->hash_lock);
                                return (0);
                        } else {
                                break;
                        }
                }
        }
        if (i == alg->hash_servers) {
                mutex_exit(&alg->hash_lock);
                return (EINVAL);
        }

#if DEBUG
        /* The server should not be in the enabled tabled. */
        {
                size_t j;

                for (j = 0; j < alg->hash_enabled_servers; j++) {
                        if (alg->hash_enabled_tbl[j].server == host) {
                                cmn_err(CE_PANIC, "Corrupted ILB enabled hash "
                                    "table");
                        }
                }
        }
#endif

        new_size = alg->hash_enabled_servers + 1;
        if (new_size > alg->hash_enabled_tbl_size) {
                if (grow_tbl(&alg->hash_enabled_tbl,
                    &alg->hash_enabled_tbl_size) != 0) {
                        mutex_exit(&alg->hash_lock);
                        return (ENOMEM);
                }
        }
        alg->hash_tbl[i].enabled = B_TRUE;
        alg->hash_enabled_tbl[alg->hash_enabled_servers].server = host;
        alg->hash_enabled_tbl[alg->hash_enabled_servers].enabled = B_TRUE;
        alg->hash_enabled_servers++;

        mutex_exit(&alg->hash_lock);
        return (0);
}

static int
hash_server_disable(ilb_server_t *host, void *alg_data)
{
        hash_t *alg = (hash_t *)alg_data;
        size_t i;

        mutex_enter(&alg->hash_lock);

        for (i = 0; i < alg->hash_servers; i++) {
                if (alg->hash_tbl[i].server == host) {
                        if (!alg->hash_tbl[i].enabled) {
                                mutex_exit(&alg->hash_lock);
                                return (0);
                        } else {
                                break;
                        }
                }
        }
        if (i == alg->hash_servers) {
                mutex_exit(&alg->hash_lock);
                return (EINVAL);
        }

        alg->hash_tbl[i].enabled = B_FALSE;
#if DEBUG
        ASSERT(del_server(alg->hash_enabled_tbl, alg->hash_enabled_servers,
            host));
#else
        (void) del_server(alg->hash_enabled_tbl, alg->hash_enabled_servers,
            host);
#endif
        alg->hash_enabled_servers--;

        mutex_exit(&alg->hash_lock);
        return (0);
}

/* ARGSUSED */
ilb_alg_data_t *
ilb_alg_hash_init(ilb_rule_t *rule, const void *arg)
{
        ilb_alg_data_t  *alg;
        hash_t          *hash_alg;
        int             flags = *(int *)arg;

        if ((alg = kmem_alloc(sizeof (ilb_alg_data_t), KM_NOSLEEP)) == NULL)
                return (NULL);
        if ((hash_alg = kmem_alloc(sizeof (hash_t), KM_NOSLEEP)) == NULL) {
                kmem_free(alg, sizeof (ilb_alg_data_t));
                return (NULL);
        }
        alg->ilb_alg_lb = hash_lb;
        alg->ilb_alg_server_del = hash_server_del;
        alg->ilb_alg_server_add = hash_server_add;
        alg->ilb_alg_server_enable = hash_server_enable;
        alg->ilb_alg_server_disable = hash_server_disable;
        alg->ilb_alg_fini = hash_fini;
        alg->ilb_alg_data = hash_alg;

        mutex_init(&hash_alg->hash_lock, NULL, MUTEX_DEFAULT, NULL);
        hash_alg->hash_type = flags;

        /* Table of all servers */
        hash_alg->hash_servers = 0;
        hash_alg->hash_tbl_size = INIT_HASH_TBL_SIZE;
        hash_alg->hash_tbl = kmem_zalloc(sizeof (hash_server_t) *
            INIT_HASH_TBL_SIZE, KM_NOSLEEP);
        if (hash_alg->hash_tbl == NULL) {
                kmem_free(hash_alg, sizeof (hash_t));
                kmem_free(alg, sizeof (ilb_alg_data_t));
                return (NULL);
        }

        /* Table of only enabled servers */
        hash_alg->hash_enabled_servers = 0;
        hash_alg->hash_enabled_tbl_size = INIT_HASH_TBL_SIZE;
        hash_alg->hash_enabled_tbl = kmem_zalloc(sizeof (hash_server_t) *
            INIT_HASH_TBL_SIZE, KM_NOSLEEP);
        if (hash_alg->hash_tbl == NULL) {
                kmem_free(hash_alg->hash_tbl, INIT_HASH_TBL_SIZE *
                    sizeof (ilb_server_t *));
                kmem_free(hash_alg, sizeof (hash_t));
                kmem_free(alg, sizeof (ilb_alg_data_t));
                return (NULL);
        }

        return (alg);
}

static void
hash_fini(ilb_alg_data_t **alg)
{
        hash_t          *hash_alg;
        int             i;

        hash_alg = (*alg)->ilb_alg_data;
        for (i = 0; i < hash_alg->hash_servers; i++)
                ILB_SERVER_REFRELE(hash_alg->hash_tbl[i].server);

        kmem_free(hash_alg->hash_tbl, sizeof (hash_server_t) *
            hash_alg->hash_tbl_size);
        kmem_free(hash_alg->hash_enabled_tbl, sizeof (hash_server_t) *
            hash_alg->hash_enabled_tbl_size);
        kmem_free(hash_alg, sizeof (hash_t));
        kmem_free(*alg, sizeof (ilb_alg_data_t));
        *alg = NULL;
}