/* Copyright (C) 2018-2022 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 Pierre Chifflier <chifflier@wzdftpd.net>

 */

#include "suricata-common.h"

#include "util-unittest.h"

#include "detect-parse.h"

#include "detect-engine.h"

#include "detect-engine-mpm.h"

#include "detect-engine-state.h"

#include "detect-engine-prefilter.h"

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

#include "detect-krb5-sname.h"

#include "rust.h"

#include "app-layer-krb5.h"

#include "util-profiling.h"

static int g_krb5_sname_buffer_id = 0;

struct Krb5PrincipalNameDataArgs {

    uint32_t local_id; /**< used as index into thread inspect array */

    void *txv;

};

static int DetectKrb5SNameSetup(DetectEngineCtx *de_ctx, Signature *s, const char *arg)

{

    if (DetectBufferSetActiveList(de_ctx, s, g_krb5_sname_buffer_id) < 0)

        return -1;

    if (DetectSignatureSetAppProto(s, ALPROTO_KRB5) != 0)

        return -1;

    return 0;

}

static InspectionBuffer *GetKrb5SNameData(DetectEngineThreadCtx *det_ctx,

        const DetectEngineTransforms *transforms, Flow *_f,

        const struct Krb5PrincipalNameDataArgs *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;

    uint32_t b_len = 0;

    const uint8_t *b = NULL;

    if (rs_krb5_tx_get_sname(cbdata->txv, cbdata->local_id, &b, &b_len) != 1) {

        InspectionBufferSetupMultiEmpty(buffer);

        return NULL;

    }

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

        InspectionBufferSetupMultiEmpty(buffer);

        return NULL;

    }

    InspectionBufferSetupMulti(buffer, transforms, b, b_len);

    SCReturnPtr(buffer, "InspectionBuffer");

}

static uint8_t DetectEngineInspectKrb5SName(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 (1) {

        struct Krb5PrincipalNameDataArgs cbdata = { local_id, txv, };

        InspectionBuffer *buffer =

                GetKrb5SNameData(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 PrefilterMpmKrb5Name {

    int list_id;

    const MpmCtx *mpm_ctx;

    const DetectEngineTransforms *transforms;

} PrefilterMpmKrb5Name;

/** \brief Krb5SName Krb5SName 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 PrefilterTxKrb5SName(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 PrefilterMpmKrb5Name *ctx = (const PrefilterMpmKrb5Name *)pectx;

    const MpmCtx *mpm_ctx = ctx->mpm_ctx;

    const int list_id = ctx->list_id;

    uint32_t local_id = 0;

    while(1) {

        // loop until we get a NULL

        struct Krb5PrincipalNameDataArgs cbdata = { local_id, txv };

        InspectionBuffer *buffer = GetKrb5SNameData(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 PrefilterMpmKrb5NameFree(void *ptr)

{

    SCFree(ptr);

}

static int PrefilterMpmKrb5SNameRegister(DetectEngineCtx *de_ctx, SigGroupHead *sgh,

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

{

    PrefilterMpmKrb5Name *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, PrefilterTxKrb5SName,

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

            pectx, PrefilterMpmKrb5NameFree, mpm_reg->name);

}

void DetectKrb5SNameRegister(void)

{

    sigmatch_table[DETECT_AL_KRB5_SNAME].name = "krb5.sname";

    sigmatch_table[DETECT_AL_KRB5_SNAME].alias = "krb5_sname";

    sigmatch_table[DETECT_AL_KRB5_SNAME].url = "/rules/kerberos-keywords.html#krb5-sname";

    sigmatch_table[DETECT_AL_KRB5_SNAME].Setup = DetectKrb5SNameSetup;

    sigmatch_table[DETECT_AL_KRB5_SNAME].flags |= SIGMATCH_NOOPT|SIGMATCH_INFO_STICKY_BUFFER;

    sigmatch_table[DETECT_AL_KRB5_SNAME].desc = "sticky buffer to match on Kerberos 5 server name";

    DetectAppLayerMpmRegister2("krb5_sname", SIG_FLAG_TOCLIENT, 2,

            PrefilterMpmKrb5SNameRegister, NULL,

            ALPROTO_KRB5, 1);

    DetectAppLayerInspectEngineRegister2("krb5_sname",

            ALPROTO_KRB5, SIG_FLAG_TOCLIENT, 0,

            DetectEngineInspectKrb5SName, NULL);

    DetectBufferTypeSetDescriptionByName("krb5_sname",

            "Kerberos 5 ticket server name");

    g_krb5_sname_buffer_id = DetectBufferTypeGetByName("krb5_sname");

    DetectBufferTypeSupportsMultiInstance("krb5_sname");

}