/* Copyright (C) 2020-2022 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 "app-layer.h"

#include "app-layer-parser.h"

#include "conf.h"

#include "decode.h"

#include "detect.h"

#include "detect-content.h"

#include "detect-parse.h"

#include "detect-pcre.h"

#include "detect-engine.h"

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

#include "detect-engine-mpm.h"

#include "detect-engine-prefilter.h"

#include "detect-mqtt-subscribe-topic.h"

#include "util-unittest.h"

#include "util-unittest-helper.h"

#include "rust-bindings.h"

#include "threads.h"

#include "flow.h"

#include "flow-util.h"

#include "flow-var.h"

#include "util-debug.h"

#include "util-spm.h"

#include "util-print.h"

#include "util-profiling.h"

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

static int g_mqtt_subscribe_topic_buffer_id = 0;

static uint32_t subscribe_topic_match_limit = 100;

struct MQTTSubscribeTopicGetDataArgs {

    uint32_t local_id;

    void *txv;

};

static InspectionBuffer *MQTTSubscribeTopicGetData(DetectEngineThreadCtx *det_ctx,

        const DetectEngineTransforms *transforms, Flow *f,

        struct MQTTSubscribeTopicGetDataArgs *cbdata, int list_id)

{

    SCEnter();

    InspectionBuffer *buffer =

            InspectionBufferMultipleForListGet(det_ctx, list_id, cbdata->local_id);

    if (buffer == NULL)

        return NULL;

    if (buffer->initialized)

        return buffer;

    const uint8_t *data;

    uint32_t data_len;

    if (rs_mqtt_tx_get_subscribe_topic(cbdata->txv, cbdata->local_id, &data, &data_len) == 0) {

        InspectionBufferSetupMultiEmpty(buffer);

        return NULL;

    }

    InspectionBufferSetupMulti(buffer, transforms, data, data_len);

    SCReturnPtr(buffer, "InspectionBuffer");

}

static uint8_t DetectEngineInspectMQTTSubscribeTopic(DetectEngineCtx *de_ctx,

        DetectEngineThreadCtx *det_ctx, const DetectEngineAppInspectionEngine *engine,

        const Signature *s, Flow *f, uint8_t flags, void *alstate, void *txv, uint64_t tx_id)

{

    uint32_t local_id = 0;

    const DetectEngineTransforms *transforms = NULL;

    if (!engine->mpm) {

        transforms = engine->v2.transforms;

    }

    while ((subscribe_topic_match_limit == 0) || local_id < subscribe_topic_match_limit) {

        struct MQTTSubscribeTopicGetDataArgs cbdata = { local_id, txv, };

        InspectionBuffer *buffer =

                MQTTSubscribeTopicGetData(det_ctx, transforms, f, &cbdata, engine->sm_list);

        if (buffer == NULL || buffer->inspect == NULL)

            break;

        det_ctx->buffer_offset = 0;

        det_ctx->discontinue_matching = 0;

        det_ctx->inspection_recursion_counter = 0;

        const int match = DetectEngineContentInspection(de_ctx, det_ctx, s, engine->smd,

                                              NULL, f,

                                              (uint8_t *)buffer->inspect,

                                              buffer->inspect_len,

                                              buffer->inspect_offset, DETECT_CI_FLAGS_SINGLE,

                                              DETECT_ENGINE_CONTENT_INSPECTION_MODE_STATE);

        if (match == 1) {

            return DETECT_ENGINE_INSPECT_SIG_MATCH;

        }

        local_id++;

    }

    return DETECT_ENGINE_INSPECT_SIG_NO_MATCH;

}

typedef struct PrefilterMpmMQTTSubscribeTopic {

    int list_id;

    const MpmCtx *mpm_ctx;

    const DetectEngineTransforms *transforms;

} PrefilterMpmMQTTSubscribeTopic;

/** \brief MQTTSubscribeTopic MQTTSubscribeTopic Mpm prefilter callback

 *

 *  \param det_ctx detection engine thread ctx

 *  \param p packet to inspect

 *  \param f flow to inspect

 *  \param txv tx to inspect

 *  \param pectx inspection context

 */

static void PrefilterTxMQTTSubscribeTopic(DetectEngineThreadCtx *det_ctx, const void *pectx,

        Packet *p, Flow *f, void *txv, const uint64_t idx, const AppLayerTxData *_txd,

        const uint8_t flags)

{

    SCEnter();

    const PrefilterMpmMQTTSubscribeTopic *ctx = (const PrefilterMpmMQTTSubscribeTopic *)pectx;

    const MpmCtx *mpm_ctx = ctx->mpm_ctx;

    const int list_id = ctx->list_id;

    uint32_t local_id = 0;

    while ((subscribe_topic_match_limit == 0) || local_id < subscribe_topic_match_limit) {

        struct MQTTSubscribeTopicGetDataArgs cbdata = { local_id, txv };

        InspectionBuffer *buffer =

                MQTTSubscribeTopicGetData(det_ctx, ctx->transforms, f, &cbdata, list_id);

        if (buffer == NULL)

            break;

        if (buffer->inspect_len >= mpm_ctx->minlen) {

            (void)mpm_table[mpm_ctx->mpm_type].Search(mpm_ctx,

                    &det_ctx->mtcu, &det_ctx->pmq,

                    buffer->inspect, buffer->inspect_len);

            PREFILTER_PROFILING_ADD_BYTES(det_ctx, buffer->inspect_len);

        }

        local_id++;

    }

}

static void PrefilterMpmMQTTSubscribeTopicFree(void *ptr)

{

    if (ptr != NULL)

        SCFree(ptr);

}

static int PrefilterMpmMQTTSubscribeTopicRegister(DetectEngineCtx *de_ctx, SigGroupHead *sgh,

        MpmCtx *mpm_ctx, const DetectBufferMpmRegistry *mpm_reg, int list_id)

{

    PrefilterMpmMQTTSubscribeTopic *pectx = SCCalloc(1, sizeof(*pectx));

    if (pectx == NULL)

        return -1;

    pectx->list_id = list_id;

    pectx->mpm_ctx = mpm_ctx;

    pectx->transforms = &mpm_reg->transforms;

    return PrefilterAppendTxEngine(de_ctx, sgh, PrefilterTxMQTTSubscribeTopic,

            mpm_reg->app_v2.alproto, mpm_reg->app_v2.tx_min_progress,

            pectx, PrefilterMpmMQTTSubscribeTopicFree, mpm_reg->pname);

}

/**

 * \brief Registration function for keyword: mqtt.subscribe.topic

 */

void DetectMQTTSubscribeTopicRegister (void)

{

    sigmatch_table[DETECT_AL_MQTT_SUBSCRIBE_TOPIC].name = "mqtt.subscribe.topic";

    sigmatch_table[DETECT_AL_MQTT_SUBSCRIBE_TOPIC].desc = "sticky buffer to match MQTT SUBSCRIBE topic";

    sigmatch_table[DETECT_AL_MQTT_SUBSCRIBE_TOPIC].url = "/rules/mqtt-keywords.html#mqtt-subscribe-topic";

    sigmatch_table[DETECT_AL_MQTT_SUBSCRIBE_TOPIC].Setup = DetectMQTTSubscribeTopicSetup;

    sigmatch_table[DETECT_AL_MQTT_SUBSCRIBE_TOPIC].flags |= SIGMATCH_NOOPT;

    sigmatch_table[DETECT_AL_MQTT_SUBSCRIBE_TOPIC].flags |= SIGMATCH_INFO_STICKY_BUFFER;

    intmax_t val = 0;

    if (ConfGetInt("app-layer.protocols.mqtt.subscribe-topic-match-limit", &val)) {

        subscribe_topic_match_limit = val;

    }

    if (subscribe_topic_match_limit <= 0) {

        SCLogDebug("Using unrestricted MQTT SUBSCRIBE topic matching");

    } else {

        SCLogDebug("Using MQTT SUBSCRIBE topic match-limit setting of: %u",

                subscribe_topic_match_limit);

    }

    DetectAppLayerMpmRegister2("mqtt.subscribe.topic", SIG_FLAG_TOSERVER, 1,

            PrefilterMpmMQTTSubscribeTopicRegister, NULL,

            ALPROTO_MQTT, 1);

    DetectAppLayerMpmRegister2("mqtt.subscribe.topic", SIG_FLAG_TOCLIENT, 1,

            PrefilterMpmMQTTSubscribeTopicRegister, NULL, ALPROTO_MQTT, 1);

    DetectAppLayerInspectEngineRegister2("mqtt.subscribe.topic",

            ALPROTO_MQTT, SIG_FLAG_TOSERVER, 1,

            DetectEngineInspectMQTTSubscribeTopic, NULL);

    DetectAppLayerInspectEngineRegister2("mqtt.subscribe.topic", ALPROTO_MQTT, SIG_FLAG_TOCLIENT, 1,

            DetectEngineInspectMQTTSubscribeTopic, NULL);

    DetectBufferTypeSetDescriptionByName("mqtt.subscribe.topic",

            "subscribe topic query");

    g_mqtt_subscribe_topic_buffer_id = DetectBufferTypeGetByName("mqtt.subscribe.topic");

    DetectBufferTypeSupportsMultiInstance("mqtt.subscribe.topic");

}

/**

 * \brief setup the sticky buffer keyword used in the rule

 *

 * \param de_ctx   Pointer to the Detection Engine Context

 * \param s        Pointer to the Signature to which the current keyword belongs

 * \param str      Should hold an empty string always

 *

 * \retval  0 On success

 * \retval -1 On failure

 */

static int DetectMQTTSubscribeTopicSetup(DetectEngineCtx *de_ctx, Signature *s, const char *str)

{

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

        return -1;

    if (DetectSignatureSetAppProto(s, ALPROTO_MQTT) < 0)

        return -1;

    return 0;

}