/* Copyright (C) 2007-2022 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 Mats Klepsland <mats.klepsland@gmail.com>

 *

 * Implements support for tls.cert_subject keyword.

 */

#include "suricata-common.h"

#include "threads.h"

#include "decode.h"

#include "detect.h"

#include "detect-parse.h"

#include "detect-engine.h"

#include "detect-engine-mpm.h"

#include "detect-engine-prefilter.h"

#include "detect-content.h"

#include "detect-pcre.h"

#include "detect-tls-cert-subject.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 "stream-tcp.h"

#include "app-layer.h"

#include "app-layer-ssl.h"

#include "util-unittest.h"

#include "util-unittest-helper.h"

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

#ifdef UNITTESTS

static void DetectTlsSubjectRegisterTests(void);

#endif

static InspectionBuffer *GetData(DetectEngineThreadCtx *det_ctx,

        const DetectEngineTransforms *transforms,

        Flow *f, const uint8_t flow_flags,

        void *txv, const int list_id);

static int g_tls_cert_subject_buffer_id = 0;

/**

 * \brief Registration function for keyword: tls.cert_subject

 */

void DetectTlsSubjectRegister(void)

{

    sigmatch_table[DETECT_AL_TLS_CERT_SUBJECT].name = "tls.cert_subject";

    sigmatch_table[DETECT_AL_TLS_CERT_SUBJECT].alias = "tls_cert_subject";

    sigmatch_table[DETECT_AL_TLS_CERT_SUBJECT].desc =

            "sticky buffer to match specifically and only on the TLS cert subject buffer";

    sigmatch_table[DETECT_AL_TLS_CERT_SUBJECT].url = "/rules/tls-keywords.html#tls-cert-subject";

    sigmatch_table[DETECT_AL_TLS_CERT_SUBJECT].Setup = DetectTlsSubjectSetup;

#ifdef UNITTESTS

    sigmatch_table[DETECT_AL_TLS_CERT_SUBJECT].RegisterTests = DetectTlsSubjectRegisterTests;

#endif

    sigmatch_table[DETECT_AL_TLS_CERT_SUBJECT].flags |= SIGMATCH_NOOPT;

    sigmatch_table[DETECT_AL_TLS_CERT_SUBJECT].flags |= SIGMATCH_INFO_STICKY_BUFFER;

    DetectAppLayerInspectEngineRegister2("tls.cert_subject", ALPROTO_TLS, SIG_FLAG_TOSERVER,

            TLS_STATE_CERT_READY, DetectEngineInspectBufferGeneric, GetData);

    DetectAppLayerMpmRegister2("tls.cert_subject", SIG_FLAG_TOSERVER, 2,

            PrefilterGenericMpmRegister, GetData, ALPROTO_TLS, TLS_STATE_CERT_READY);

    DetectAppLayerInspectEngineRegister2("tls.cert_subject", ALPROTO_TLS, SIG_FLAG_TOCLIENT,

            TLS_STATE_CERT_READY, DetectEngineInspectBufferGeneric, GetData);

    DetectAppLayerMpmRegister2("tls.cert_subject", SIG_FLAG_TOCLIENT, 2,

            PrefilterGenericMpmRegister, GetData, ALPROTO_TLS,

            TLS_STATE_CERT_READY);

    DetectBufferTypeSupportsMultiInstance("tls.cert_subject");

    DetectBufferTypeSetDescriptionByName("tls.cert_subject",

            "TLS certificate subject");

    g_tls_cert_subject_buffer_id = DetectBufferTypeGetByName("tls.cert_subject");

}

/**

 * \brief this function setup the tls.cert_subject modifier 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 DetectTlsSubjectSetup(DetectEngineCtx *de_ctx, Signature *s, const char *str)

{

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

        return -1;

    if (DetectSignatureSetAppProto(s, ALPROTO_TLS) < 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 SSLState *ssl_state = (SSLState *)f->alstate;

        const SSLStateConnp *connp;

        if (flow_flags & STREAM_TOSERVER) {

            connp = &ssl_state->client_connp;

        } else {

            connp = &ssl_state->server_connp;

        }

        if (connp->cert0_subject == NULL) {

            return NULL;

        }

        const uint32_t data_len = strlen(connp->cert0_subject);

        const uint8_t *data = (uint8_t *)connp->cert0_subject;

        InspectionBufferSetup(det_ctx, list_id, buffer, data, data_len);

        InspectionBufferApplyTransforms(buffer, transforms);

    }

    return buffer;

}

#ifdef UNITTESTS

#include "tests/detect-tls-cert-subject.c"

#endif