/* Copyright (C) 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.

 */

#include "suricata-common.h"

#include "threads.h"

#include "detect.h"

#include "detect-parse.h"

#include "detect-engine.h"

#include "detect-engine-buffer.h"

#include "detect-engine-mpm.h"

#include "detect-content.h"

#include "flow.h"

#include "stream-tcp.h"

#include "app-layer.h"

#include "app-layer-ssl.h"

#include "detect-engine-prefilter.h"

#include "detect-tls-random.h"

#define DETECT_TLS_RANDOM_TIME_LEN  4

#define DETECT_TLS_RANDOM_BYTES_LEN 28

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

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

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

static InspectionBuffer *GetRandomTimeData(DetectEngineThreadCtx *det_ctx,

        const DetectEngineTransforms *transforms, Flow *f, const uint8_t flow_flags, void *txv,

        const int list_id);

static InspectionBuffer *GetRandomBytesData(DetectEngineThreadCtx *det_ctx,

        const DetectEngineTransforms *transforms, Flow *f, const uint8_t flow_flags, void *txv,

        const int list_id);

static InspectionBuffer *GetRandomData(DetectEngineThreadCtx *det_ctx,

        const DetectEngineTransforms *transforms, Flow *f, const uint8_t flow_flags, void *txv,

        const int list_id);

static int g_tls_random_time_buffer_id = 0;

static int g_tls_random_bytes_buffer_id = 0;

static int g_tls_random_buffer_id = 0;

void DetectTlsRandomTimeRegister(void)

{

    sigmatch_table[DETECT_TLS_RANDOM_TIME].name = "tls.random_time";

    sigmatch_table[DETECT_TLS_RANDOM_TIME].desc = "sticky buffer to match specifically and only "

                                                  "on the first 4 bytes of a TLS random buffer";

    sigmatch_table[DETECT_TLS_RANDOM_TIME].url = "/rules/tls-keywords.html#tls-random-time";

    sigmatch_table[DETECT_TLS_RANDOM_TIME].Setup = DetectTlsRandomTimeSetup;

    sigmatch_table[DETECT_TLS_RANDOM_TIME].flags |= SIGMATCH_NOOPT | SIGMATCH_INFO_STICKY_BUFFER;

    /* Register engine for Server random */

    DetectAppLayerInspectEngineRegister("tls.random_time", ALPROTO_TLS, SIG_FLAG_TOSERVER,

            TLS_STATE_CLIENT_HELLO_DONE, DetectEngineInspectBufferGeneric, GetRandomTimeData);

    DetectAppLayerMpmRegister("tls.random_time", SIG_FLAG_TOSERVER, 2, PrefilterGenericMpmRegister,

            GetRandomTimeData, ALPROTO_TLS, TLS_STATE_CLIENT_HELLO_DONE);

    /* Register engine for Client random */

    DetectAppLayerInspectEngineRegister("tls.random_time", ALPROTO_TLS, SIG_FLAG_TOCLIENT,

            TLS_STATE_SERVER_HELLO, DetectEngineInspectBufferGeneric, GetRandomTimeData);

    DetectAppLayerMpmRegister("tls.random_time", SIG_FLAG_TOCLIENT, 2, PrefilterGenericMpmRegister,

            GetRandomTimeData, ALPROTO_TLS, TLS_STATE_SERVER_HELLO);

    DetectBufferTypeSetDescriptionByName("tls.random_time", "TLS Random Time");

    g_tls_random_time_buffer_id = DetectBufferTypeGetByName("tls.random_time");

}

void DetectTlsRandomBytesRegister(void)

{

    sigmatch_table[DETECT_TLS_RANDOM_BYTES].name = "tls.random_bytes";

    sigmatch_table[DETECT_TLS_RANDOM_BYTES].desc =

            "sticky buffer to match specifically and only on the last 28 bytes of a TLS random "

            "buffer";

    sigmatch_table[DETECT_TLS_RANDOM_BYTES].url = "/rules/tls-keywords.html#tls-random-bytes";

    sigmatch_table[DETECT_TLS_RANDOM_BYTES].Setup = DetectTlsRandomBytesSetup;

    sigmatch_table[DETECT_TLS_RANDOM_BYTES].flags |= SIGMATCH_NOOPT | SIGMATCH_INFO_STICKY_BUFFER;

    /* Register engine for Server random */

    DetectAppLayerInspectEngineRegister("tls.random_bytes", ALPROTO_TLS, SIG_FLAG_TOSERVER,

            TLS_STATE_CLIENT_HELLO_DONE, DetectEngineInspectBufferGeneric, GetRandomBytesData);

    DetectAppLayerMpmRegister("tls.random_bytes", SIG_FLAG_TOSERVER, 2, PrefilterGenericMpmRegister,

            GetRandomBytesData, ALPROTO_TLS, TLS_STATE_CLIENT_HELLO_DONE);

    /* Register engine for Client random */

    DetectAppLayerInspectEngineRegister("tls.random_bytes", ALPROTO_TLS, SIG_FLAG_TOCLIENT,

            TLS_STATE_SERVER_HELLO, DetectEngineInspectBufferGeneric, GetRandomBytesData);

    DetectAppLayerMpmRegister("tls.random_bytes", SIG_FLAG_TOCLIENT, 2, PrefilterGenericMpmRegister,

            GetRandomBytesData, ALPROTO_TLS, TLS_STATE_SERVER_HELLO);

    DetectBufferTypeSetDescriptionByName("tls.random_bytes", "TLS Random Bytes");

    g_tls_random_bytes_buffer_id = DetectBufferTypeGetByName("tls.random_bytes");

}

/**

 * \brief Registration function for keyword: tls.random

 */

void DetectTlsRandomRegister(void)

{

    DetectTlsRandomTimeRegister();

    DetectTlsRandomBytesRegister();

    sigmatch_table[DETECT_TLS_RANDOM].name = "tls.random";

    sigmatch_table[DETECT_TLS_RANDOM].desc =

            "sticky buffer to match specifically and only on a TLS random buffer";

    sigmatch_table[DETECT_TLS_RANDOM].url = "/rules/tls-keywords.html#tls-random";

    sigmatch_table[DETECT_TLS_RANDOM].Setup = DetectTlsRandomSetup;

    sigmatch_table[DETECT_TLS_RANDOM].flags |= SIGMATCH_NOOPT | SIGMATCH_INFO_STICKY_BUFFER;

    /* Register engine for Server random */

    DetectAppLayerInspectEngineRegister("tls.random", ALPROTO_TLS, SIG_FLAG_TOSERVER, 0,

            DetectEngineInspectBufferGeneric, GetRandomData);

    DetectAppLayerMpmRegister("tls.random", SIG_FLAG_TOSERVER, 2, PrefilterGenericMpmRegister,

            GetRandomData, ALPROTO_TLS, 0);

    /* Register engine for Client random */

    DetectAppLayerInspectEngineRegister("tls.random", ALPROTO_TLS, SIG_FLAG_TOCLIENT, 0,

            DetectEngineInspectBufferGeneric, GetRandomData);

    DetectAppLayerMpmRegister("tls.random", SIG_FLAG_TOCLIENT, 2, PrefilterGenericMpmRegister,

            GetRandomData, ALPROTO_TLS, 0);

    DetectBufferTypeSetDescriptionByName("tls.random", "TLS Random");

    g_tls_random_buffer_id = DetectBufferTypeGetByName("tls.random");

}

/**

 * \brief this function setup the tls.random_time 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 DetectTlsRandomTimeSetup(DetectEngineCtx *de_ctx, Signature *s, const char *str)

{

    if (SCDetectBufferSetActiveList(de_ctx, s, g_tls_random_time_buffer_id) < 0)

        return -1;

    if (SCDetectSignatureSetAppProto(s, ALPROTO_TLS) < 0)

        return -1;

    return 0;

}

/**

 * \brief this function setup the tls.random_bytes 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 DetectTlsRandomBytesSetup(DetectEngineCtx *de_ctx, Signature *s, const char *str)

{

    if (SCDetectBufferSetActiveList(de_ctx, s, g_tls_random_bytes_buffer_id) < 0)

        return -1;

    if (SCDetectSignatureSetAppProto(s, ALPROTO_TLS) < 0)

        return -1;

    return 0;

}

/**

 * \brief this function setup the tls.random 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 DetectTlsRandomSetup(DetectEngineCtx *de_ctx, Signature *s, const char *str)

{

    if (SCDetectBufferSetActiveList(de_ctx, s, g_tls_random_buffer_id) < 0)

        return -1;

    if (SCDetectSignatureSetAppProto(s, ALPROTO_TLS) < 0)

        return -1;

    return 0;

}

static InspectionBuffer *GetRandomTimeData(DetectEngineThreadCtx *det_ctx,

        const DetectEngineTransforms *transforms, Flow *f, const uint8_t flow_flags, void *txv,

        const int list_id)

{

    InspectionBuffer *buffer = SCInspectionBufferGet(det_ctx, list_id);

    if (buffer->inspect == NULL) {

        const SSLState *ssl_state = (SSLState *)f->alstate;

        if (flow_flags & STREAM_TOSERVER) {

            if (!(ssl_state->flags & TLS_TS_RANDOM_SET))

                return NULL;

        } else {

            if (!(ssl_state->flags & TLS_TC_RANDOM_SET))

                return NULL;

        }

        const uint8_t *data;

        if (flow_flags & STREAM_TOSERVER) {

            data = ssl_state->client_connp.random;

        } else {

            data = ssl_state->server_connp.random;

        }

        SCInspectionBufferSetupAndApplyTransforms(

                det_ctx, list_id, buffer, data, DETECT_TLS_RANDOM_TIME_LEN, transforms);

    }

    return buffer;

}

static InspectionBuffer *GetRandomBytesData(DetectEngineThreadCtx *det_ctx,

        const DetectEngineTransforms *transforms, Flow *f, const uint8_t flow_flags, void *txv,

        const int list_id)

{

    InspectionBuffer *buffer = SCInspectionBufferGet(det_ctx, list_id);

    if (buffer->inspect == NULL) {

        const SSLState *ssl_state = (SSLState *)f->alstate;

        if (flow_flags & STREAM_TOSERVER) {

            if (!(ssl_state->flags & TLS_TS_RANDOM_SET))

                return NULL;

        } else {

            if (!(ssl_state->flags & TLS_TC_RANDOM_SET))

                return NULL;

        }

        const uint8_t *data;

        if (flow_flags & STREAM_TOSERVER) {

            data = ssl_state->client_connp.random + DETECT_TLS_RANDOM_TIME_LEN;

        } else {

            data = ssl_state->server_connp.random + DETECT_TLS_RANDOM_TIME_LEN;

        }

        SCInspectionBufferSetupAndApplyTransforms(

                det_ctx, list_id, buffer, data, DETECT_TLS_RANDOM_BYTES_LEN, transforms);

    }

    return buffer;

}

static InspectionBuffer *GetRandomData(DetectEngineThreadCtx *det_ctx,

        const DetectEngineTransforms *transforms, Flow *f, const uint8_t flow_flags, void *txv,

        const int list_id)

{

    InspectionBuffer *buffer = SCInspectionBufferGet(det_ctx, list_id);

    if (buffer->inspect == NULL) {

        const SSLState *ssl_state = (SSLState *)f->alstate;

        if (flow_flags & STREAM_TOSERVER) {

            if (!(ssl_state->flags & TLS_TS_RANDOM_SET))

                return NULL;

        } else {

            if (!(ssl_state->flags & TLS_TC_RANDOM_SET))

                return NULL;

        }

        const uint8_t *data;

        if (flow_flags & STREAM_TOSERVER) {

            data = ssl_state->client_connp.random;

        } else {

            data = ssl_state->server_connp.random;

        }

        SCInspectionBufferSetupAndApplyTransforms(

                det_ctx, list_id, buffer, data, TLS_RANDOM_LEN, transforms);

    }

    return buffer;

}