/*
 *  Copyright (C) 2013-2021 Cisco Systems, Inc. and/or its affiliates. All rights reserved.
 *  Copyright (C) 2010-2013 Sourcefire, Inc.
 *
 *  Authors: aCaB
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it 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
 *  along with this program; if not, write to the Free Software
 *  Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
 *  MA 02110-1301, USA.
 */

#include <string.h>
#include <stdlib.h>

#include "matcher.h"
#include "others.h"
#include "str.h"

int hm_addhash_str(struct cli_matcher *root, const char *strhash, uint32_t size, const char *virusname)
{
    enum CLI_HASH_TYPE type;
    char binhash[CLI_HASHLEN_MAX];
    int hlen;

    if (!root || !strhash) {
        cli_errmsg("hm_addhash_str: NULL root or hash\n");
        return CL_ENULLARG;
    }

    /* size 0 here is now a wildcard size match */
    if (size == (uint32_t)-1) {
        cli_errmsg("hm_addhash_str: null or invalid size (%u)\n", size);
        return CL_EARG;
    }

    hlen = strlen(strhash);
    switch (hlen) {
        case 32:
            type = CLI_HASH_MD5;
            break;
        case 40:
            type = CLI_HASH_SHA1;
            break;
        case 64:
            type = CLI_HASH_SHA256;
            break;
        default:
            cli_errmsg("hm_addhash_str: invalid hash %s -- FIXME!\n", strhash);
            return CL_EARG;
    }
    if (cli_hex2str_to(strhash, (char *)binhash, hlen)) {
        cli_errmsg("hm_addhash_str: invalid hash %s\n", strhash);
        return CL_EARG;
    }

    return hm_addhash_bin(root, binhash, type, size, virusname);
}

const unsigned int hashlen[] = {
    CLI_HASHLEN_MD5,
    CLI_HASHLEN_SHA1,
    CLI_HASHLEN_SHA256};

int hm_addhash_bin(struct cli_matcher *root, const void *binhash, enum CLI_HASH_TYPE type, uint32_t size, const char *virusname)
{
    const unsigned int hlen = hashlen[type];
    const struct cli_htu32_element *item;
    struct cli_sz_hash *szh;
    struct cli_htu32 *ht;
    int i;

    if (size) {
        /* size non-zero, find sz_hash element in size-driven hashtable  */
        ht = &root->hm.sizehashes[type];
        if (!root->hm.sizehashes[type].capacity) {
            i = cli_htu32_init(ht, 64, root->mempool);
            if (i) return i;
        }

        item = cli_htu32_find(ht, size);
        if (!item) {
            struct cli_htu32_element htitem;
            szh = MPOOL_CALLOC(root->mempool, 1, sizeof(*szh));
            if (!szh) {
                cli_errmsg("hm_addhash_bin: failed to allocate size hash\n");
                return CL_EMEM;
            }

            htitem.key         = size;
            htitem.data.as_ptr = szh;
            i                  = cli_htu32_insert(ht, &htitem, root->mempool);
            if (i) {
                cli_errmsg("hm_addhash_bin: failed to add item to hashtab");
                MPOOL_FREE(root->mempool, szh);
                return i;
            }
        } else
            szh = (struct cli_sz_hash *)item->data.as_ptr;
    } else {
        /* size 0 = wildcard */
        szh = &root->hwild.hashes[type];
    }
    szh->items++;

    szh->hash_array = MPOOL_REALLOC2(root->mempool, szh->hash_array, hlen * szh->items);
    if (!szh->hash_array) {
        cli_errmsg("hm_addhash_bin: failed to grow hash array to %u entries\n", szh->items);
        szh->items = 0;
        MPOOL_FREE(root->mempool, szh->virusnames);
        szh->virusnames = NULL;
        return CL_EMEM;
    }

    szh->virusnames = MPOOL_REALLOC2(root->mempool, szh->virusnames, sizeof(*szh->virusnames) * szh->items);
    if (!szh->virusnames) {
        cli_errmsg("hm_addhash_bin: failed to grow virusname array to %u entries\n", szh->items);
        szh->items = 0;
        MPOOL_FREE(root->mempool, szh->hash_array);
        szh->hash_array = NULL;
        return CL_EMEM;
    }

    memcpy(&szh->hash_array[(szh->items - 1) * hlen], binhash, hlen);
    szh->virusnames[(szh->items - 1)] = virusname;

    return 0;
}

static inline int hm_cmp(const uint8_t *itm, const uint8_t *ref, unsigned int keylen)
{
#if WORDS_BIGENDIAN == 0
    uint32_t i = *(uint32_t *)itm, r = *(uint32_t *)ref;
    if (i != r)
        return (i < r) * 2 - 1;
    return memcmp(&itm[4], &ref[4], keylen - 4);
#else
    return memcmp(itm, ref, keylen);
#endif
}

static void hm_sort(struct cli_sz_hash *szh, size_t l, size_t r, unsigned int keylen)
{
    uint8_t piv[CLI_HASHLEN_MAX], tmph[CLI_HASHLEN_MAX];
    size_t l1, r1;

    const char *tmpv;

    if (l + 1 >= r)
        return;

    l1 = l + 1, r1 = r;

    memcpy(piv, &szh->hash_array[keylen * l], keylen);
    while (l1 < r1) {
        if (hm_cmp(&szh->hash_array[keylen * l1], piv, keylen) > 0) {
            r1--;
            if (l1 == r1) break;
            memcpy(tmph, &szh->hash_array[keylen * l1], keylen);
            tmpv = szh->virusnames[l1];
            memcpy(&szh->hash_array[keylen * l1], &szh->hash_array[keylen * r1], keylen);
            szh->virusnames[l1] = szh->virusnames[r1];
            memcpy(&szh->hash_array[keylen * r1], tmph, keylen);
            szh->virusnames[r1] = tmpv;
        } else
            l1++;
    }

    l1--;
    if (l1 != l) {
        memcpy(tmph, &szh->hash_array[keylen * l1], keylen);
        tmpv = szh->virusnames[l1];
        memcpy(&szh->hash_array[keylen * l1], &szh->hash_array[keylen * l], keylen);
        szh->virusnames[l1] = szh->virusnames[l];
        memcpy(&szh->hash_array[keylen * l], tmph, keylen);
        szh->virusnames[l] = tmpv;
    }

    hm_sort(szh, l, l1, keylen);
    hm_sort(szh, r1, r, keylen);
}

/* flush both size-specific and agnostic hash sets */
void hm_flush(struct cli_matcher *root)
{
    enum CLI_HASH_TYPE type;
    unsigned int keylen;
    struct cli_sz_hash *szh;

    if (!root)
        return;

    for (type = CLI_HASH_MD5; type < CLI_HASH_AVAIL_TYPES; type++) {
        struct cli_htu32 *ht                 = &root->hm.sizehashes[type];
        const struct cli_htu32_element *item = NULL;
        szh                                  = NULL;

        if (!root->hm.sizehashes[type].capacity)
            continue;

        while ((item = cli_htu32_next(ht, item))) {
            szh    = (struct cli_sz_hash *)item->data.as_ptr;
            keylen = hashlen[type];

            if (szh->items > 1)
                hm_sort(szh, 0, szh->items, keylen);
        }
    }

    for (type = CLI_HASH_MD5; type < CLI_HASH_AVAIL_TYPES; type++) {
        szh    = &root->hwild.hashes[type];
        keylen = hashlen[type];

        if (szh->items > 1)
            hm_sort(szh, 0, szh->items, keylen);
    }
}

int cli_hm_have_size(const struct cli_matcher *root, enum CLI_HASH_TYPE type, uint32_t size)
{
    return (size && size != 0xffffffff && root && root->hm.sizehashes[type].capacity && cli_htu32_find(&root->hm.sizehashes[type], size));
}

int cli_hm_have_wild(const struct cli_matcher *root, enum CLI_HASH_TYPE type)
{
    return (root && root->hwild.hashes[type].items);
}

int cli_hm_have_any(const struct cli_matcher *root, enum CLI_HASH_TYPE type)
{
    return (root && (root->hwild.hashes[type].items || root->hm.sizehashes[type].capacity));
}

/* cli_hm_scan will scan only size-specific hashes, if any */
static int hm_scan(const unsigned char *digest, const char **virname, const struct cli_sz_hash *szh, enum CLI_HASH_TYPE type)
{
    unsigned int keylen;
    size_t l, r;

    if (!digest || !szh || !szh->items)
        return CL_CLEAN;

    keylen = hashlen[type];

    l = 0;
    r = szh->items - 1;
    while (l <= r) {
        size_t c = (l + r) / 2;
        int res  = hm_cmp(digest, &szh->hash_array[keylen * c], keylen);

        if (res < 0) {
            if (!c)
                break;
            r = c - 1;
        } else if (res > 0)
            l = c + 1;
        else {
            if (virname)
                *virname = szh->virusnames[c];
            return CL_VIRUS;
        }
    }
    return CL_CLEAN;
}

/* cli_hm_scan will scan only size-specific hashes, if any */
int cli_hm_scan(const unsigned char *digest, uint32_t size, const char **virname, const struct cli_matcher *root, enum CLI_HASH_TYPE type)
{
    const struct cli_htu32_element *item;
    struct cli_sz_hash *szh;

    if (!digest || !size || size == 0xffffffff || !root || !root->hm.sizehashes[type].capacity)
        return CL_CLEAN;

    item = cli_htu32_find(&root->hm.sizehashes[type], size);
    if (!item)
        return CL_CLEAN;

    szh = (struct cli_sz_hash *)item->data.as_ptr;

    return hm_scan(digest, virname, szh, type);
}

/* cli_hm_scan_wild will scan only size-agnostic hashes, if any */
int cli_hm_scan_wild(const unsigned char *digest, const char **virname, const struct cli_matcher *root, enum CLI_HASH_TYPE type)
{
    if (!digest || !root || !root->hwild.hashes[type].items)
        return CL_CLEAN;

    return hm_scan(digest, virname, &root->hwild.hashes[type], type);
}

/* free both size-specific and agnostic hash sets */
void hm_free(struct cli_matcher *root)
{
    enum CLI_HASH_TYPE type;

    if (!root)
        return;

    for (type = CLI_HASH_MD5; type < CLI_HASH_AVAIL_TYPES; type++) {
        struct cli_htu32 *ht                 = &root->hm.sizehashes[type];
        const struct cli_htu32_element *item = NULL;

        if (!root->hm.sizehashes[type].capacity)
            continue;

        while ((item = cli_htu32_next(ht, item))) {
            struct cli_sz_hash *szh = (struct cli_sz_hash *)item->data.as_ptr;

            MPOOL_FREE(root->mempool, szh->hash_array);
            while (szh->items)
                MPOOL_FREE(root->mempool, (void *)szh->virusnames[--szh->items]);
            MPOOL_FREE(root->mempool, szh->virusnames);
            MPOOL_FREE(root->mempool, szh);
        }
        cli_htu32_free(ht, root->mempool);
    }

    for (type = CLI_HASH_MD5; type < CLI_HASH_AVAIL_TYPES; type++) {
        struct cli_sz_hash *szh = &root->hwild.hashes[type];

        if (!szh->items)
            continue;

        MPOOL_FREE(root->mempool, szh->hash_array);
        while (szh->items)
            MPOOL_FREE(root->mempool, (void *)szh->virusnames[--szh->items]);
        MPOOL_FREE(root->mempool, szh->virusnames);
    }
}
