/* 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.

 */

/**

 *

 * \author Sascha Steinbiss <sascha@steinbiss.name>

 *

 * Implements the mqtt.connect.clientid sticky buffer

 */

#include "suricata-common.h"

#include "detect.h"

#include "detect-parse.h"

#include "detect-engine.h"

#include "detect-engine-mpm.h"

#include "detect-engine-prefilter.h"

#include "detect-mqtt-connect-clientid.h"

#include "rust.h"

#define KEYWORD_NAME "mqtt.connect.clientid"

#define KEYWORD_DOC  "mqtt-keywords.html#mqtt-connect-clientid"

#define BUFFER_NAME  "mqtt.connect.clientid"

#define BUFFER_DESC  "MQTT CONNECT client ID"

static int g_buffer_id = 0;

static int DetectMQTTConnectClientIDSetup(DetectEngineCtx *de_ctx, Signature *s, const char *arg)

{

    if (DetectBufferSetActiveList(de_ctx, s, g_buffer_id) < 0)

        return -1;

    if (DetectSignatureSetAppProto(s, ALPROTO_MQTT) < 0)

        return -1;

    return 0;

}

static InspectionBuffer *GetData(DetectEngineThreadCtx *det_ctx,

        const DetectEngineTransforms *transforms,

        Flow *_f, const uint8_t _flow_flags,

        void *txv, const int list_id)

{

    InspectionBuffer *buffer = InspectionBufferGet(det_ctx, list_id);

    if (buffer->inspect == NULL) {

        const uint8_t *b = NULL;

        uint32_t b_len = 0;

        if (rs_mqtt_tx_get_connect_clientid(txv, &b, &b_len) != 1)

            return NULL;

        if (b == NULL || b_len == 0)

            return NULL;

        InspectionBufferSetup(det_ctx, list_id, buffer, b, b_len);

        InspectionBufferApplyTransforms(buffer, transforms);

    }

    return buffer;

}

void DetectMQTTConnectClientIDRegister(void)

{

    /* mqtt.connect.clientid sticky buffer */

    sigmatch_table[DETECT_AL_MQTT_CONNECT_CLIENTID].name = KEYWORD_NAME;

    sigmatch_table[DETECT_AL_MQTT_CONNECT_CLIENTID].desc = "sticky buffer to match on the MQTT CONNECT client ID";

    sigmatch_table[DETECT_AL_MQTT_CONNECT_CLIENTID].url = "/rules/" KEYWORD_DOC;

    sigmatch_table[DETECT_AL_MQTT_CONNECT_CLIENTID].Setup = DetectMQTTConnectClientIDSetup;

    sigmatch_table[DETECT_AL_MQTT_CONNECT_CLIENTID].flags |= SIGMATCH_NOOPT;

    DetectAppLayerInspectEngineRegister2(BUFFER_NAME, ALPROTO_MQTT,

            SIG_FLAG_TOSERVER, 0,

            DetectEngineInspectBufferGeneric, GetData);

    DetectAppLayerMpmRegister2(BUFFER_NAME, SIG_FLAG_TOSERVER, 2,

            PrefilterGenericMpmRegister, GetData, ALPROTO_MQTT,

          1);

    DetectBufferTypeSetDescriptionByName(BUFFER_NAME, BUFFER_DESC);

    g_buffer_id = DetectBufferTypeGetByName(BUFFER_NAME);

    SCLogDebug("registering " BUFFER_NAME " rule option");

}