clamav/libclamav/regex_list.c

/*
 *  Match a string against a list of patterns/regexes.
 *
 *  Copyright (C) 2013-2022 Cisco Systems, Inc. and/or its affiliates. All rights reserved.
 *  Copyright (C) 2007-2013 Sourcefire, Inc.
 *
 *  Authors: Török Edvin
 *
 *  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.
 */

#if HAVE_CONFIG_H
#include "clamav-config.h"
#endif

#ifdef CL_THREAD_SAFE
#ifndef _REENTRANT
#define _REENTRANT
#endif
#endif

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>
#include <zlib.h>

#include <limits.h>
#include <sys/types.h>
#include <assert.h>

#include "regex/regex.h"

#include "clamav.h"
#include "others.h"
#include "regex_list.h"
#include "matcher-ac.h"
#include "matcher.h"
#include "str.h"
#include "readdb.h"
#include "jsparse/textbuf.h"
#include "regex_suffix.h"
#include "default.h"
#include "hashtab.h"

#include "mpool.h"

/* Prototypes */
static regex_t *new_preg(struct regex_matcher *matcher);
static size_t reverse_string(char *pattern);
static cl_error_t add_pattern_suffix(void *cbdata, const char *suffix, size_t suffix_len, const struct regex_list *regex);
static cl_error_t add_static_pattern(struct regex_matcher *matcher, char *pattern);
/* ---------- */

#define MATCH_SUCCESS 0
#define MATCH_FAILED -1

/*
 * Call this function when an unrecoverable error has occurred, (instead of exit).
 */
static void fatal_error(struct regex_matcher *matcher)
{
    regex_list_done(matcher);
    matcher->list_inited = -1; /* the phishing module will know we tried to load an allow list, and failed, so it will disable itself too*/
}

static inline char get_char_at_pos_with_skip(const struct pre_fixup_info *info, const char *buffer, size_t pos)
{
    const char *str;
    size_t realpos = 0;
    if (!info) {
        return (pos <= strlen(buffer)) ? buffer[pos > 0 ? pos - 1 : 0] : '\0';
    }
    str = info->pre_displayLink.data;
    cli_dbgmsg("calc_pos_with_skip: skip:%llu, %llu - %llu \"%s\",\"%s\"\n", (long long unsigned)pos, (long long unsigned)info->host_start,
               (long long unsigned)info->host_end, str, buffer);
    pos += info->host_start;
    while (str[realpos] && !isalnum(str[realpos])) realpos++;
    for (; str[realpos] && (pos > 0); pos--) {
        while (str[realpos] == ' ') realpos++;
        realpos++;
    }
    while (str[realpos] == ' ') realpos++;
    cli_dbgmsg("calc_pos_with_skip:%s\n", str + realpos);
    return (pos > 0 && !str[realpos]) ? '\0' : str[realpos > 0 ? realpos - 1 : 0];
}

static int validate_subdomain(const struct regex_list *regex, const struct pre_fixup_info *pre_fixup, const char *buffer, size_t buffer_len, char *real_url, size_t real_len, char *orig_real_url)
{
    char c;
    size_t match_len;

    if (!regex || !regex->pattern)
        return 0;
    match_len = strlen(regex->pattern);
    if (((c = get_char_at_pos_with_skip(pre_fixup, buffer, buffer_len + 1)) == ' ' || c == '\0' || c == '/' || c == '?') &&
        (match_len == buffer_len || /* full match */
         (match_len < buffer_len &&
          ((c = get_char_at_pos_with_skip(pre_fixup, buffer, buffer_len - match_len)) == '.' || (c == ' ')))
         /* subdomain matched*/)) {
        /* we have an extra / at the end */
        if (match_len > 0) match_len--;
        cli_dbgmsg("Got a match: %s with %s\n", buffer, regex->pattern);
        cli_dbgmsg("Before inserting .: %s\n", orig_real_url);
        if (real_len >= match_len + 1) {
            const size_t pos = real_len - match_len - 1;
            if (real_url[pos] != '.') {
                /* we need to shift left, and insert a '.'
                 * we have an extra '.' at the beginning inserted by get_host to have room,
                 * orig_real_url has to be used here,
                 * because we want to overwrite that extra '.' */
                size_t orig_real_len = strlen(orig_real_url);
                cli_dbgmsg("No dot here:%s\n", real_url + pos);
                real_url = orig_real_url;
                memmove(real_url, real_url + 1, orig_real_len - match_len - 1);
                real_url[orig_real_len - match_len - 1] = '.';
                cli_dbgmsg("After inserting .: %s\n", real_url);
            }
        }
        return 1;
    }
    cli_dbgmsg("Ignoring false match: %s with %s, mismatched character: %c\n", buffer, regex->pattern, c);
    return 0;
}

/*
 * @matcher - matcher structure to use
 * @real_url - href target
 * @display_url - <a> tag contents
 * @hostOnly - if you want to match only the host part
 * @is_allow_list_lookup - is this a lookup in an allow list?
 *
 * @return - CL_SUCCESS - url doesn't match
 *         - CL_VIRUS - url matches list
 *
 * Do not send NULL pointers to this function!!
 *
 */
cl_error_t regex_list_match(struct regex_matcher *matcher, char *real_url, const char *display_url, const struct pre_fixup_info *pre_fixup, int hostOnly, const char **info, int is_allow_list_lookup)
{
    char *orig_real_url = real_url;
    struct regex_list *regex;
    size_t real_len, display_len, buffer_len;

    char *buffer  = NULL;
    char *bufrev  = NULL;
    cl_error_t rc = CL_SUCCESS;
    // int filter_search_rc = 0;
    int root;
    struct cli_ac_data mdata;
    struct cli_ac_result *res = NULL;

    assert(matcher);
    assert(real_url);
    assert(display_url);
    *info = NULL;
    if (!matcher->list_inited)
        return CL_SUCCESS;
    assert(matcher->list_built);
    /* skip initial '.' inserted by get_host */
    if (real_url[0] == '.') real_url++;
    if (display_url[0] == '.') display_url++;
    real_len    = strlen(real_url);
    display_len = strlen(display_url);
    buffer_len  = (hostOnly && !is_allow_list_lookup) ? real_len + 1 : real_len + display_len + 1 + 1;
    if (buffer_len < 3) {
        /* too short, no match possible */
        return CL_SUCCESS;
    }
    buffer = cli_malloc(buffer_len + 1);
    if (!buffer) {
        cli_errmsg("regex_list_match: Unable to allocate memory for buffer\n");
        return CL_EMEM;
    }

    strncpy(buffer, real_url, real_len);
    buffer[real_len] = (!is_allow_list_lookup && hostOnly) ? '/' : ':';

    /*
     * For H-type PDB signatures, real_url is actually the DisplayedHostname.
     * RealHostname is not used.
     */
    if (!hostOnly || is_allow_list_lookup) {
        /* For all other PDB and WDB signatures concatenate Real:Displayed. */
        strncpy(buffer + real_len + 1, display_url, display_len);
    }
    buffer[buffer_len - 1] = '/';
    buffer[buffer_len]     = 0;
    cli_dbgmsg("Looking up in regex_list: %s\n", buffer);

    if (CL_SUCCESS != (rc = cli_ac_initdata(&mdata, 0, 0, 0, CLI_DEFAULT_AC_TRACKLEN)))
        return rc;

    bufrev = cli_strdup(buffer);
    if (!bufrev)
        return CL_EMEM;

    reverse_string(bufrev);
    // TODO Add this back in once we improve the regex parsing code that finds
    // suffixes to add to the filter.
    //
    // Reviewing Coverity bug reports we found that the return value to this
    // filter_search call was effectively being ignored, causing no filtering
    // to occur. Fixing this issue resulted in a unit test that uses the
    // following match list regex to fail when searching for `ebay.com`.:
    //
    // .+\\.paypal\\.(com|de|fr|it)([/?].*)?:.+\\.ebay\\.(at|be|ca|ch|co\\.uk|de|es|fr|ie|in|it|nl|ph|pl|com(\\.(au|cn|hk|my|sg))?)/
    //
    // After investigating further, this is because the regex_list_add_pattern
    // call, which parses the regex for suffixes and attempts to add these to
    // the filter, can't handle the `com(\\.(au|cn|hk|my|sg))?` portion of
    // the regex. As a result, it only adds `ebay.at`, `ebay.be`, `ebay.ca`, up
    // through `ebay.pl` into the filter). With the commented out code below
    // uncommented, these suffixes not existing in the filter are treated as
    // there not being a corresponding regex for ebay.com, causing no regex
    // rules to be evaluated against the URL.
    //
    // We should get the regex parsing code working (and ensure it handles any
    // other complex cases in daily.cdb) before re-enabling this code. The code
    // has had no effect for 12+ years at this point, though, so it's probably
    // safe to wait a bit longer without it.
    //
    // filter_search_rc = filter_search(&matcher->filter, (const unsigned char *)bufrev, buffer_len);
    // if (filter_search_rc == -1) {
    //    free(buffer);
    //    free(bufrev);
    //    /* filter says this suffix doesn't match.
    //     * The filter has false positives, but no false
    //     * negatives */
    //    return CL_SUCCESS;
    //}

    rc = cli_ac_scanbuff((const unsigned char *)bufrev, buffer_len, NULL, (void *)&regex, &res, &matcher->suffixes, &mdata, 0, 0, NULL, AC_SCAN_VIR, NULL);
    free(bufrev);
    cli_ac_freedata(&mdata);

    rc   = CL_SUCCESS;
    root = matcher->root_regex_idx;
    while (res || root) {
        struct cli_ac_result *q;
        if (!res) {
            regex = matcher->suffix_regexes[root].head;
            root  = 0;
        } else {
            regex = res->customdata;
        }
        while (!rc && regex) {
            /* loop over multiple regexes corresponding to
             * this suffix */
            if (!regex->preg) {
                /* we matched a static pattern */
                rc = validate_subdomain(regex, pre_fixup, buffer, buffer_len, real_url, real_len, orig_real_url);
            } else {
                rc = !cli_regexec(regex->preg, buffer, 0, NULL, 0);
            }
            if (rc) *info = regex->pattern;
            regex = regex->nxt;
        }
        if (res) {
            q   = res;
            res = res->next;
            free(q);
        }
    }
    free(buffer);
    if (!rc)
        cli_dbgmsg("Lookup result: not in regex list\n");
    else
        cli_dbgmsg("Lookup result: in regex list\n");
    return rc;
}

/* Initialization & loading */
/* Initializes @matcher, allocating necessary substructures */
cl_error_t init_regex_list(struct regex_matcher *matcher, uint8_t dconf_prefiltering)
{
#ifdef USE_MPOOL
    mpool_t *mp = matcher->mempool;
#endif
    cl_error_t rc;

    assert(matcher);
    memset(matcher, 0, sizeof(*matcher));

    matcher->list_inited = 1;
    matcher->list_built  = 0;
    matcher->list_loaded = 0;
    cli_hashtab_init(&matcher->suffix_hash, 512);
#ifdef USE_MPOOL
    matcher->mempool          = mp;
    matcher->suffixes.mempool = mp;
    assert(mp && "mempool must be initialized");
#endif
    if ((rc = cli_ac_init(&matcher->suffixes, 2, 32, dconf_prefiltering))) {
        return rc;
    }
#ifdef USE_MPOOL
    matcher->sha256_hashes.mempool  = mp;
    matcher->hostkey_prefix.mempool = mp;
#endif
    if ((rc = cli_bm_init(&matcher->sha256_hashes))) {
        return rc;
    }
    if ((rc = cli_bm_init(&matcher->hostkey_prefix))) {
        return rc;
    }
    filter_init(&matcher->filter);
    return CL_SUCCESS;
}

static int functionality_level_check(char *line)
{
    char *ptmin;
    char *ptmax;
    size_t j;

    ptmin = strrchr(line, ':');
    if (!ptmin)
        return CL_SUCCESS;

    ptmin++;

    ptmax = strchr(ptmin, '-');
    if (!ptmax)
        return CL_SUCCESS; /* there is no functionality level specified, so we're ok */
    else {
        size_t min, max;
        ptmax++;
        for (j = 0; j + ptmin + 1 < ptmax; j++)
            if (!isdigit(ptmin[j]))
                return CL_SUCCESS; /* not numbers, not functionality level */
        for (j = 0; j < strlen(ptmax); j++)
            if (!isdigit(ptmax[j]))
                return CL_SUCCESS; /* see above */
        ptmax[-1] = '\0';
        min       = atoi(ptmin);
        if (strlen(ptmax) == 0)
            max = INT_MAX;
        else
            max = atoi(ptmax);

        if (min > cl_retflevel()) {
            cli_dbgmsg("regex list line %s not loaded (required f-level: %u)\n", line, (unsigned int)min);
            return CL_EMALFDB;
        }

        if (max < cl_retflevel())
            return CL_EMALFDB;
        ptmin[-1] = '\0';
        return CL_SUCCESS;
    }
}

static int add_hash(struct regex_matcher *matcher, char *pattern, const char fl, int is_prefix)
{
    int rc;
    struct cli_bm_patt *pat = MPOOL_CALLOC(matcher->mempool, 1, sizeof(*pat));
    struct cli_matcher *bm;
    const char *vname = NULL;
    if (!pat)
        return CL_EMEM;
    pat->pattern = (unsigned char *)CLI_MPOOL_HEX2STR(matcher->mempool, pattern);
    if (!pat->pattern)
        return CL_EMALFDB;
    pat->length = 32;
    if (is_prefix) {
        pat->length = 4;
        bm          = &matcher->hostkey_prefix;
    } else {
        bm = &matcher->sha256_hashes;
    }

    if (!matcher->sha256_pfx_set.keys) {
        if ((rc = cli_hashset_init(&matcher->sha256_pfx_set, 1048576, 90))) {
            return rc;
        }
    }

    if (fl != 'W' && pat->length == 32 &&
        cli_hashset_contains(&matcher->sha256_pfx_set, cli_readint32(pat->pattern)) &&
        cli_bm_scanbuff(pat->pattern, 32, &vname, NULL, &matcher->sha256_hashes, 0, NULL, NULL, NULL) == CL_VIRUS) {
        if (*vname == 'W') {
            /* hash is allowed in local.gdb */
            cli_dbgmsg("Skipping hash %s\n", pattern);
            MPOOL_FREE(matcher->mempool, pat->pattern);
            MPOOL_FREE(matcher->mempool, pat);
            return CL_SUCCESS;
        }
    }
    pat->virname = MPOOL_MALLOC(matcher->mempool, 1);
    if (!pat->virname) {
        free(pat);
        cli_errmsg("add_hash: Unable to allocate memory for path->virname\n");
        return CL_EMEM;
    }
    *pat->virname = fl;
    cli_hashset_addkey(&matcher->sha256_pfx_set, cli_readint32(pat->pattern));
    if ((rc = cli_bm_addpatt(bm, pat, "*"))) {
        cli_errmsg("add_hash: failed to add BM pattern\n");
        free(pat->pattern);
        free(pat->virname);
        free(pat);
        return CL_EMALFDB;
    }
    return CL_SUCCESS;
}

/* Load patterns/regexes from file */
cl_error_t load_regex_matcher(struct cl_engine *engine, struct regex_matcher *matcher, FILE *fd, unsigned int *signo, unsigned int options, int is_allow_list_lookup, struct cli_dbio *dbio, uint8_t dconf_prefiltering)
{
    cl_error_t rc;
    int line = 0, entry = 0;
    char buffer[FILEBUFF];

    assert(matcher);

    if (matcher->list_inited == -1)
        return CL_EMALFDB; /* already failed to load */
    if (!fd && !dbio) {
        cli_errmsg("Unable to load regex list (null file)\n");
        return CL_ENULLARG;
    }

    cli_dbgmsg("Loading regex_list\n");
    if (!matcher->list_inited) {
        rc = init_regex_list(matcher, dconf_prefiltering);
        if (!matcher->list_inited) {
            cli_errmsg("Regex list failed to initialize!\n");
            fatal_error(matcher);
            return rc;
        }
    }
    /*
     * Regexlist db format, common to .wdb (allow list) and .pdb (domain list) files.
     *
     * Multiple lines of form, (empty lines are skipped):
     * Flags RealURL DisplayedURL
     * Where:
     * Flags:
     *
     * .pdb files:
     * R - regex, H - host-only, followed by (optional) 3-digit hexnumber representing
     * flags that should be filtered.
     * [i.e. phishcheck urls.flags that we don't want to be done for this particular host]
     *
     * .wdb files:
     * X - full URL regex
     * Y - host-only regex
     * M - host simple pattern
     *
     * If a line in the file doesn't conform to this format, loading fails
     *
     */
    while (cli_dbgets(buffer, FILEBUFF, fd, dbio)) {
        char *pattern;
        char *flags;
        size_t pattern_len;

        cli_chomp(buffer);
        line++;
        if (!*buffer)
            continue; /* skip empty lines */

        if (buffer[0] == '#')
            continue;

        if (functionality_level_check(buffer))
            continue;

        if (engine->cb_sigload && engine->cb_sigload("phishing", buffer, ~options & CL_DB_OFFICIAL, engine->cb_sigload_ctx)) {
            cli_dbgmsg("load_regex_matcher: skipping %s due to callback\n", buffer);
            continue;
        }

        entry++;
        pattern = strchr(buffer, ':');
        if (!pattern) {
            cli_errmsg("Malformed regex list line %d\n", line);
            fatal_error(matcher);
            return CL_EMALFDB;
        }
        /*pattern[0]='\0';*/
        flags = buffer + 1;
        pattern++;

        pattern_len = strlen(pattern);
        /* '-3' to leave room for the '/' and null being
         * appended below.
         */
        if ((pattern - buffer) + pattern_len < (FILEBUFF - 3)) {
            pattern[pattern_len]     = '/';
            pattern[pattern_len + 1] = '\0';
        } else {
            cli_errmsg("Overlong regex line %d\n", line);
            fatal_error(matcher);
            return CL_EMALFDB;
        }

        if ((buffer[0] == 'R' && !is_allow_list_lookup) || ((buffer[0] == 'X' || buffer[0] == 'Y') && is_allow_list_lookup)) {
            /* regex for hostname*/
            if ((rc = regex_list_add_pattern(matcher, pattern)))
                return rc == CL_EMEM ? CL_EMEM : CL_EMALFDB;
        } else if ((buffer[0] == 'H' && !is_allow_list_lookup) || (buffer[0] == 'M' && is_allow_list_lookup)) {
            /*matches displayed host*/
            if ((rc = add_static_pattern(matcher, pattern)))
                return rc == CL_EMEM ? CL_EMEM : CL_EMALFDB;
        } else if (buffer[0] == 'S' && (!is_allow_list_lookup || pattern[0] == 'W')) {
            pattern[pattern_len] = '\0';
            if (pattern[0] == 'W')
                flags[0] = 'W';
            if ((pattern[0] == 'W' || pattern[0] == 'F' || pattern[0] == 'P') && pattern[1] == ':') {
                pattern += 2;
                if ((rc = add_hash(matcher, pattern, flags[0], pattern[-2] == 'P'))) {
                    cli_errmsg("Error loading at line: %d\n", line);
                    return rc == CL_EMEM ? CL_EMEM : CL_EMALFDB;
                }
            } else {
                cli_errmsg("Error loading line: %d, %c\n", line, *pattern);
                return CL_EMALFDB;
            }
        } else {
            return CL_EMALFDB;
        }
    }
    matcher->list_loaded = 1;
    if (signo)
        *signo += entry;

    return CL_SUCCESS;
}

/* Build the matcher list */
cl_error_t cli_build_regex_list(struct regex_matcher *matcher)
{
    cl_error_t rc;
    if (!matcher)
        return CL_SUCCESS;
    if (!matcher->list_inited || !matcher->list_loaded) {
        cli_errmsg("Regex list not loaded!\n");
        return -1; /*TODO: better error code */
    }
    cli_dbgmsg("Building regex list\n");
    cli_hashtab_free(&matcher->suffix_hash);
    if ((rc = cli_ac_buildtrie(&matcher->suffixes)))
        return rc;
    matcher->list_built = 1;
    cli_hashset_destroy(&matcher->sha256_pfx_set);

    return CL_SUCCESS;
}

/* Done with this matcher, free resources */
void regex_list_done(struct regex_matcher *matcher)
{
    assert(matcher);

    if (matcher->list_inited == 1) {
        size_t i;
        cli_ac_free(&matcher->suffixes);
        if (matcher->suffix_regexes) {
            for (i = 0; i < matcher->suffix_cnt; i++) {
                struct regex_list *r = matcher->suffix_regexes[i].head;
                while (r) {
                    struct regex_list *q = r;
                    r                    = r->nxt;
                    free(q->pattern);
                    free(q);
                }
            }
            free(matcher->suffix_regexes);
            matcher->suffix_regexes = NULL;
        }
        if (matcher->all_pregs) {
            for (i = 0; i < matcher->regex_cnt; i++) {
                regex_t *r = matcher->all_pregs[i];
                cli_regfree(r);
                MPOOL_FREE(matcher->mempool, r);
            }
            MPOOL_FREE(matcher->mempool, matcher->all_pregs);
        }
        cli_hashtab_free(&matcher->suffix_hash);
        cli_bm_free(&matcher->sha256_hashes);
        cli_bm_free(&matcher->hostkey_prefix);
    }
}

int is_regex_ok(struct regex_matcher *matcher)
{
    assert(matcher);
    return (!matcher->list_inited || matcher->list_inited != -1); /* either we don't have a regexlist, or we initialized it successfully */
}

static int add_newsuffix(struct regex_matcher *matcher, struct regex_list *info, const char *suffix, size_t len)
{
    struct cli_matcher *root = &matcher->suffixes;
    struct cli_ac_patt *new  = MPOOL_CALLOC(matcher->mempool, 1, sizeof(*new));
    size_t i;
    int ret;

    if (!new)
        return CL_EMEM;
    assert(root && suffix);

    new->rtype      = 0;
    new->type       = 0;
    new->sigid      = 0;
    new->parts      = 0;
    new->partno     = 0;
    new->mindist    = 0;
    new->maxdist    = 0;
    new->offset_min = CLI_OFF_ANY;
    new->length[0]  = (uint16_t)len;

    new->ch[0] = new->ch[1] |= CLI_MATCH_IGNORE;
    if (new->length[0] > root->maxpatlen)
        root->maxpatlen = new->length[0];

    new->pattern = MPOOL_MALLOC(matcher->mempool, sizeof(new->pattern[0]) * len);
    if (!new->pattern) {
        MPOOL_FREE(matcher->mempool, new);
        cli_errmsg("add_newsuffix: Unable to allocate memory for new->pattern\n");
        return CL_EMEM;
    }
    for (i = 0; i < len; i++)
        new->pattern[i] = suffix[i]; /*new->pattern is short int* */

    new->customdata = info;
    new->virname    = NULL;
    if ((ret = cli_ac_addpatt(root, new))) {
        MPOOL_FREE(matcher->mempool, new->pattern);
        MPOOL_FREE(matcher->mempool, new);
        return ret;
    }
    filter_add_static(&matcher->filter, (const unsigned char *)suffix, len, "regex");
    return CL_SUCCESS;
}

#define MODULE "regex_list: "
/* ------ load a regex, determine suffix, determine suffix2regexlist map ---- */

static void list_add_tail(struct regex_list_ht *ht, struct regex_list *regex)
{
    if (!ht->head)
        ht->head = regex;
    if (ht->tail) {
        ht->tail->nxt = regex;
    }
    ht->tail = regex;
}

static cl_error_t add_pattern_suffix(void *cbdata, const char *suffix, size_t suffix_len, const struct regex_list *iregex)
{
    struct regex_matcher *matcher = cbdata;
    struct regex_list *regex      = cli_malloc(sizeof(*regex));
    const struct cli_element *el;
    void *tmp_matcher; /*	save original address if OOM occurs */

    assert(matcher);
    if (!regex) {
        cli_errmsg("add_pattern_suffix: Unable to allocate memory for regex\n");
        return CL_EMEM;
    }
    regex->pattern = iregex->pattern ? cli_strdup(iregex->pattern) : NULL;
    regex->preg    = iregex->preg;
    regex->nxt     = NULL;
    el             = cli_hashtab_find(&matcher->suffix_hash, suffix, suffix_len);
    /* TODO: what if suffixes are prefixes of eachother and only one will
     * match? */
    if (el) {
        /* existing suffix */
        assert((size_t)el->data < matcher->suffix_cnt);
        list_add_tail(&matcher->suffix_regexes[(size_t)el->data], regex);
    } else {
        /* new suffix */
        size_t n    = matcher->suffix_cnt;
        el          = cli_hashtab_insert(&matcher->suffix_hash, suffix, suffix_len, (cli_element_data)n);
        tmp_matcher = matcher->suffix_regexes; /*  save the current value before cli_realloc()	*/
        tmp_matcher = cli_realloc(matcher->suffix_regexes, (n + 1) * sizeof(*matcher->suffix_regexes));
        if (!tmp_matcher) {
            FREE(regex->pattern);
            free(regex);
            return CL_EMEM;
        }
        matcher->suffix_regexes         = tmp_matcher; /*  success, point at new memory location   */
        matcher->suffix_regexes[n].tail = regex;
        matcher->suffix_regexes[n].head = regex;
        matcher->suffix_cnt++;
        if (suffix[0] == '/' && suffix[1] == '\0')
            matcher->root_regex_idx = n;
        add_newsuffix(matcher, regex, suffix, suffix_len);
    }
    return CL_SUCCESS;
}

static size_t reverse_string(char *pattern)
{
    size_t len = strlen(pattern);
    size_t i;
    for (i = 0; i < (len / 2); i++) {
        char aux             = pattern[i];
        pattern[i]           = pattern[len - i - 1];
        pattern[len - i - 1] = aux;
    }
    return len;
}

static regex_t *new_preg(struct regex_matcher *matcher)
{
    regex_t *r;
    matcher->all_pregs = MPOOL_REALLOC(matcher->mempool, matcher->all_pregs, ++matcher->regex_cnt * sizeof(*matcher->all_pregs));
    if (!matcher->all_pregs) {
        cli_errmsg("new_preg: Unable to reallocate memory\n");
        return NULL;
    }
    r = MPOOL_MALLOC(matcher->mempool, sizeof(*r));
    if (!r) {
        cli_errmsg("new_preg: Unable to allocate memory\n");
        return NULL;
    }
    matcher->all_pregs[matcher->regex_cnt - 1] = r;
    return r;
}

static cl_error_t add_static_pattern(struct regex_matcher *matcher, char *pattern)
{
    size_t len;
    struct regex_list regex;
    cl_error_t rc;

    len           = reverse_string(pattern);
    regex.nxt     = NULL;
    regex.pattern = cli_strdup(pattern);
    regex.preg    = NULL;
    rc            = add_pattern_suffix(matcher, pattern, len, &regex);
    free(regex.pattern);
    return rc;
}

cl_error_t regex_list_add_pattern(struct regex_matcher *matcher, char *pattern)
{
    cl_error_t rc;
    regex_t *preg;
    size_t len;
    /* we only match the host, so remove useless stuff */
    const char remove_end[]  = "([/?].*)?/";
    const char remove_end2[] = "([/?].*)/";

    len = strlen(pattern);
    if (len > sizeof(remove_end)) {
        if (strncmp(&pattern[len - sizeof(remove_end) + 1], remove_end, sizeof(remove_end) - 1) == 0) {
            len -= sizeof(remove_end) - 1;
            pattern[len++] = '/';
        }
        if (strncmp(&pattern[len - sizeof(remove_end2) + 1], remove_end2, sizeof(remove_end2) - 1) == 0) {
            len -= sizeof(remove_end2) - 1;
            pattern[len++] = '/';
        }
    }
    pattern[len] = '\0';

    preg = new_preg(matcher);
    if (!preg)
        return CL_EMEM;

    rc = cli_regex2suffix(pattern, preg, add_pattern_suffix, (void *)matcher);
    if (rc) {
        cli_regfree(preg);
    }

    return rc;
}