/* Copyright (C) 2020 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.name>

 */

#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-mqtt-flags.h"

#include "util-unittest.h"

#include "rust.h"

#define PARSE_REGEX "(?: *,?!?(?:retain|dup))+"

static DetectParseRegex parse_regex;

static int mqtt_flags_id = 0;

static int DetectMQTTFlagsMatch(DetectEngineThreadCtx *det_ctx,

                               Flow *f, uint8_t flags, void *state,

                               void *txv, const Signature *s,

                               const SigMatchCtx *ctx);

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

void MQTTFlagsRegisterTests(void);

void DetectMQTTFlagsFree(DetectEngineCtx *de_ctx, void *);

typedef struct DetectMQTTFlagsData_ {

    MQTTFlagState retain, dup;

} DetectMQTTFlagsData;

/**

 * \brief Registration function for mqtt.flags: keyword

 */

void DetectMQTTFlagsRegister (void)

{

    sigmatch_table[DETECT_AL_MQTT_FLAGS].name = "mqtt.flags";

    sigmatch_table[DETECT_AL_MQTT_FLAGS].desc = "match MQTT fixed header flags";

    sigmatch_table[DETECT_AL_MQTT_FLAGS].url = "/rules/mqtt-keywords.html#mqtt-flags";

    sigmatch_table[DETECT_AL_MQTT_FLAGS].AppLayerTxMatch = DetectMQTTFlagsMatch;

    sigmatch_table[DETECT_AL_MQTT_FLAGS].Setup = DetectMQTTFlagsSetup;

    sigmatch_table[DETECT_AL_MQTT_FLAGS].Free  = DetectMQTTFlagsFree;

#ifdef UNITTESTS

    sigmatch_table[DETECT_AL_MQTT_FLAGS].RegisterTests = MQTTFlagsRegisterTests;

#endif

    DetectSetupParseRegexes(PARSE_REGEX, &parse_regex);

    DetectAppLayerInspectEngineRegister2(

            "mqtt.flags", ALPROTO_MQTT, SIG_FLAG_TOSERVER, 1, DetectEngineInspectGenericList, NULL);

    mqtt_flags_id = DetectBufferTypeGetByName("mqtt.flags");

}

/**

 * \internal

 * \brief Function to match fixed header flags of an MQTT 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 transaction.

 * \param s       Pointer to the Signature.

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

 *

 * \retval 0 no match.

 * \retval 1 match.

 */

static int DetectMQTTFlagsMatch(DetectEngineThreadCtx *det_ctx,

                               Flow *f, uint8_t flags, void *state,

                               void *txv, const Signature *s,

                               const SigMatchCtx *ctx)

{

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

    if (!de)

        return 0;

    return rs_mqtt_tx_has_flags(txv, de->retain, de->dup);

}

/**

 * \internal

 * \brief This function is used to parse options passed via mqtt.flags: keyword

 *

 * \param rawstr Pointer to the user provided options

 *

 * \retval de pointer to DetectMQTTFlagsData on success

 * \retval NULL on failure

 */

static DetectMQTTFlagsData *DetectMQTTFlagsParse(const char *rawstr)

{

    DetectMQTTFlagsData *de = SCCalloc(1, sizeof(DetectMQTTFlagsData));

    if (unlikely(de == NULL))

        return NULL;

    pcre2_match_data *match = NULL;

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

    if (ret < 1) {

        SCLogError("invalid flag definition: %s", rawstr);

        if (match) {

            pcre2_match_data_free(match);

        }

        SCFree(de);

        return NULL;

    }

    de->retain = de->dup = MQTT_DONT_CARE;

    char copy[strlen(rawstr)+1];

    strlcpy(copy, rawstr, sizeof(copy));

    char *xsaveptr = NULL;

    /* Iterate through comma-separated string... */

    char *flagv = strtok_r(copy, ",", &xsaveptr);

    while (flagv != NULL) {

        /* skip blanks */

        while (*flagv != '\0' && isblank(*flagv)) {

            flagv++;

        }

        if (strlen(flagv) < 2) {

            /* flags have a minimum length */

            SCLogError("malformed flag value: %s", flagv);

            goto error;

        }  else {

            int offset = 0;

            MQTTFlagState fs_to_set = MQTT_MUST_BE_SET;

            if (flagv[0] == '!') {

                /* negated flag */

                offset = 1;  /* skip negation operator during comparison */

                fs_to_set = MQTT_CANT_BE_SET;

            }

            if (strcmp(flagv+offset, "dup") == 0) {

                if (de->dup != MQTT_DONT_CARE) {

                    SCLogError("duplicate flag definition: %s", flagv);

                    goto error;

                }

                de->dup = fs_to_set;

            } else if (strcmp(flagv+offset, "retain") == 0) {

                if (de->retain != MQTT_DONT_CARE) {

                    SCLogError("duplicate flag definition: %s", flagv);

                    goto error;

                }

                de->retain = fs_to_set;

            } else {

                SCLogError("invalid flag definition: %s", flagv);

                goto error;

            }

        }

        flagv = strtok_r(NULL, ",", &xsaveptr);

    }

    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 type query 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 options

 *

 * \retval 0 on Success

 * \retval -1 on Failure

 */

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

{

    DetectMQTTFlagsData *de = NULL;

    SigMatch *sm = NULL;

    if (DetectSignatureSetAppProto(s, ALPROTO_MQTT) < 0)

        return -1;

    de = DetectMQTTFlagsParse(rawstr);

    if (de == NULL)

        goto error;

    sm = SigMatchAlloc();

    if (sm == NULL)

        goto error;

    sm->type = DETECT_AL_MQTT_FLAGS;

    sm->ctx = (SigMatchCtx *)de;

    SigMatchAppendSMToList(s, sm, mqtt_flags_id);

    return 0;

error:

    if (de != NULL)

        SCFree(de);

    if (sm != NULL)

        SCFree(sm);

    return -1;

}

/**

 * \internal

 * \brief this function will free memory associated with DetectMQTTFlagsData

 *

 * \param de pointer to DetectMQTTFlagsData

 */

void DetectMQTTFlagsFree(DetectEngineCtx *de_ctx, void *de_ptr)

{

    if (de_ptr != NULL)

        SCFree(de_ptr);

}

/*

 * ONLY TESTS BELOW THIS COMMENT

 */

#ifdef UNITTESTS

/**

 * \test MQTTFlagsTestParse01 is a test for a valid value

 *

 *  \retval 1 on success

 *  \retval 0 on failure

 */

static int MQTTFlagsTestParse01 (void)

{

    DetectMQTTFlagsData *de = NULL;

    de = DetectMQTTFlagsParse("retain");

    FAIL_IF_NULL(de);

    DetectMQTTFlagsFree(NULL, de);

    de = DetectMQTTFlagsParse("dup");

    FAIL_IF_NULL(de);

    DetectMQTTFlagsFree(NULL, de);

    de = DetectMQTTFlagsParse("retain,dup");

    FAIL_IF_NULL(de);

    DetectMQTTFlagsFree(NULL, de);

    de = DetectMQTTFlagsParse("dup, retain");

    FAIL_IF_NULL(de);

    DetectMQTTFlagsFree(NULL, de);

    PASS;

}

/**

 * \test MQTTFlagsTestParse02 is a test for a valid value

 *

 *  \retval 1 on success

 *  \retval 0 on failure

 */

static int MQTTFlagsTestParse02 (void)

{

    DetectMQTTFlagsData *de = NULL;

    de = DetectMQTTFlagsParse("retain,!dup");

    FAIL_IF_NULL(de);

    DetectMQTTFlagsFree(NULL, de);

    PASS;

}

/**

 * \test MQTTFlagsTestParse03 is a test for an invalid value

 *

 *  \retval 1 on success

 *  \retval 0 on failure

 */

static int MQTTFlagsTestParse03 (void)

{

    DetectMQTTFlagsData *de = NULL;

    de = DetectMQTTFlagsParse("ref");

    if (de) {

        DetectMQTTFlagsFree(NULL, de);

        FAIL;

    }

    PASS;

}

/**

 * \test MQTTFlagsTestParse04 is a test for an invalid value

 *

 *  \retval 1 on success

 *  \retval 0 on failure

 */

static int MQTTFlagsTestParse04 (void)

{

    DetectMQTTFlagsData *de = NULL;

    de = DetectMQTTFlagsParse("dup,!");

    if (de) {

        DetectMQTTFlagsFree(NULL, de);

        FAIL;

    }

    PASS;

}

/**

 * \test MQTTFlagsTestParse05 is a test for an invalid value

 *

 *  \retval 1 on success

 *  \retval 0 on failure

 */

static int MQTTFlagsTestParse05 (void)

{

    DetectMQTTFlagsData *de = NULL;

    de = DetectMQTTFlagsParse("dup,!dup");

    if (de) {

        DetectMQTTFlagsFree(NULL, de);

        FAIL;

    }

    de = DetectMQTTFlagsParse("!retain,retain");

    if (de) {

        DetectMQTTFlagsFree(NULL, de);

        FAIL;

    }

    PASS;

}

#endif /* UNITTESTS */

/**

 * \brief this function registers unit tests for MQTTFlags

 */

void MQTTFlagsRegisterTests(void)

{

#ifdef UNITTESTS

    UtRegisterTest("MQTTFlagsTestParse01", MQTTFlagsTestParse01);

    UtRegisterTest("MQTTFlagsTestParse02", MQTTFlagsTestParse02);

    UtRegisterTest("MQTTFlagsTestParse03", MQTTFlagsTestParse03);

    UtRegisterTest("MQTTFlagsTestParse04", MQTTFlagsTestParse04);

    UtRegisterTest("MQTTFlagsTestParse05", MQTTFlagsTestParse05);

#endif /* UNITTESTS */

}