/* Copyright (C) 2020-2021 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 Sascha Steinbiss <sascha.steinbiss@dcso.de>

 */

#include "suricata-common.h"

#include "conf.h"

#include "detect.h"

#include "detect-parse.h"

#include "detect-engine.h"

#include "detect-engine-content-inspection.h"

#include "detect-rfb-secresult.h"

#include "util-unittest.h"

#include "rust.h"

#define PARSE_REGEX "\\S[A-z]"

static DetectParseRegex parse_regex;

static int rfb_secresult_id = 0;

static int DetectRfbSecresultMatch(DetectEngineThreadCtx *det_ctx,

                                   Flow *f, uint8_t flags, void *state,

                                   void *txv, const Signature *s,

                                   const SigMatchCtx *ctx);

static int DetectRfbSecresultSetup (DetectEngineCtx *, Signature *, const char *);

#ifdef UNITTESTS

static void RfbSecresultRegisterTests(void);

#endif

void DetectRfbSecresultFree(DetectEngineCtx *, void *);

typedef struct DetectRfbSecresultData_ {

    uint32_t result; /** result code */

} DetectRfbSecresultData;

/**

 * \brief Registration function for rfb.secresult: keyword

 */

void DetectRfbSecresultRegister (void)

{

    sigmatch_table[DETECT_AL_RFB_SECRESULT].name = "rfb.secresult";

    sigmatch_table[DETECT_AL_RFB_SECRESULT].desc = "match RFB security result";

    sigmatch_table[DETECT_AL_RFB_SECRESULT].url = "/rules/rfb-keywords.html#rfb-secresult";

    sigmatch_table[DETECT_AL_RFB_SECRESULT].AppLayerTxMatch = DetectRfbSecresultMatch;

    sigmatch_table[DETECT_AL_RFB_SECRESULT].Setup = DetectRfbSecresultSetup;

    sigmatch_table[DETECT_AL_RFB_SECRESULT].Free  = DetectRfbSecresultFree;

#ifdef UNITTESTS

    sigmatch_table[DETECT_AL_RFB_SECRESULT].RegisterTests = RfbSecresultRegisterTests;

#endif

    DetectSetupParseRegexes(PARSE_REGEX, &parse_regex);

    DetectAppLayerInspectEngineRegister2("rfb.secresult", ALPROTO_RFB, SIG_FLAG_TOCLIENT, 1,

            DetectEngineInspectGenericList, NULL);

    rfb_secresult_id = DetectBufferTypeGetByName("rfb.secresult");

}

enum {

    RFB_SECRESULT_OK = 0,

    RFB_SECRESULT_FAIL,

    RFB_SECRESULT_TOOMANY,

    RFB_SECRESULT_UNKNOWN

};

/**

 * \struct DetectRfbSecresult_

 * DetectRfbSecresult_ is used to store values

 */

struct DetectRfbSecresult_ {

    const char *result;

    uint16_t code;

} results[] = {

    { "ok", RFB_SECRESULT_OK, },

    { "fail", RFB_SECRESULT_FAIL, },

    { "toomany", RFB_SECRESULT_TOOMANY, },

    { "unknown", RFB_SECRESULT_UNKNOWN, },

    { NULL, 0 },

};

/**

 * \internal

 * \brief Function to match security result of a RFB TX

 *

 * \param det_ctx Pointer to the pattern matcher thread.

 * \param f       Pointer to the current flow.

 * \param flags   Flags.

 * \param state   App layer state.

 * \param txv     Pointer to the RFBTransaction.

 * \param s       Pointer to the Signature.

 * \param ctx     Pointer to the sigmatch that we will cast into DetectRfbSecresultData.

 *

 * \retval 0 no match.

 * \retval 1 match.

 */

static int DetectRfbSecresultMatch(DetectEngineThreadCtx *det_ctx,

                                   Flow *f, uint8_t flags, void *state,

                                   void *txv, const Signature *s,

                                   const SigMatchCtx *ctx)

{

    const DetectRfbSecresultData *de = (const DetectRfbSecresultData *)ctx;

    uint32_t resultcode;

    int ret = 0;

    if (!de)

        return 0;

    ret = rs_rfb_tx_get_secresult(txv, &resultcode);

    if (ret == 0) {

        return 0;

    }

    if (de->result < 3) {

        /* we are asking for a defined code... */

        if (resultcode == de->result) {

            /* ... which needs to match */

            return 1;

        }

    } else {

        /* we are asking for an unknown code */

        if (resultcode > 2) {

            /* match any unknown code */

            return 1;

        }

    }

    return 0;

}

/**

 * \internal

 * \brief This function is used to parse options passed via rfb.secresults: keyword

 *

 * \param rawstr Pointer to the user provided secresult options

 *

 * \retval de pointer to DetectRfbSecresultData on success

 * \retval NULL on failure

 */

static DetectRfbSecresultData *DetectRfbSecresultParse (const char *rawstr)

{

    int i;

    DetectRfbSecresultData *de = NULL;

    int found = 0;

    pcre2_match_data *match = NULL;

    int ret = DetectParsePcreExec(&parse_regex, &match, rawstr, 0, 0);

    if (ret < 1) {

        SCLogError("pcre_exec parse error, ret %" PRId32 ", string %s", ret, rawstr);

        goto error;

    }

    for(i = 0; results[i].result != NULL; i++)  {

        if((strcasecmp(results[i].result,rawstr)) == 0) {

            found = 1;

            break;

        }

    }

    if(found == 0) {

        SCLogError("unknown secresult value %s", rawstr);

        goto error;

    }

    de = SCMalloc(sizeof(DetectRfbSecresultData));

    if (unlikely(de == NULL))

        goto error;

    de->result = results[i].code;

    pcre2_match_data_free(match);

    return de;

error:

    if (match) {

        pcre2_match_data_free(match);

    }

    if (de) SCFree(de);

    return NULL;

}

/**

 * \internal

 * \brief this function is used to add the parsed secresult into the current signature

 *

 * \param de_ctx pointer to the Detection Engine Context

 * \param s pointer to the Current Signature

 * \param rawstr pointer to the user provided secresult options

 *

 * \retval 0 on Success

 * \retval -1 on Failure

 */

static int DetectRfbSecresultSetup (DetectEngineCtx *de_ctx, Signature *s, const char *rawstr)

{

    DetectRfbSecresultData *de = NULL;

    SigMatch *sm = NULL;

    if (DetectSignatureSetAppProto(s, ALPROTO_RFB) < 0)

        return -1;

    de = DetectRfbSecresultParse(rawstr);

    if (de == NULL)

        goto error;

    sm = SigMatchAlloc();

    if (sm == NULL)

        goto error;

    sm->type = DETECT_AL_RFB_SECRESULT;

    sm->ctx = (SigMatchCtx *)de;

    SigMatchAppendSMToList(s, sm, rfb_secresult_id);

    return 0;

error:

    if (de) SCFree(de);

    if (sm) SCFree(sm);

    return -1;

}

/**

 * \internal

 * \brief this function will free memory associated with DetectRfbSecresultData

 *

 * \param de pointer to DetectRfbSecresultData

 */

void DetectRfbSecresultFree(DetectEngineCtx *de_ctx, void *de_ptr)

{

    DetectRfbSecresultData *de = (DetectRfbSecresultData *)de_ptr;

    if(de) SCFree(de);

}

/*

 * ONLY TESTS BELOW THIS COMMENT

 */

#ifdef UNITTESTS

/**

 * \test RfbSecresultTestParse01 is a test for a valid secresult value

 */

static int RfbSecresultTestParse01 (void)

{

    DetectRfbSecresultData *de = DetectRfbSecresultParse("fail");

    FAIL_IF_NULL(de);

    DetectRfbSecresultFree(NULL, de);

    PASS;

}

/**

 * \test RfbSecresultTestParse02 is a test for an invalid secresult value

 */

static int RfbSecresultTestParse02 (void)

{

    DetectRfbSecresultData *de = DetectRfbSecresultParse("invalidopt");

    FAIL_IF_NOT_NULL(de);

    PASS;

}

/**

 * \brief this function registers unit tests for RfbSecresult

 */

void RfbSecresultRegisterTests(void)

{

    UtRegisterTest("RfbSecresultTestParse01", RfbSecresultTestParse01);

    UtRegisterTest("RfbSecresultTestParse02", RfbSecresultTestParse02);

}

#endif /* UNITTESTS */