/* Copyright (C) 2007-2020 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.

 */

/**

 * \file

 *

 * \author Victor Julien <victor@inliniac.net>

 *

 * Implements the tls.version keyword

 */

#include "suricata-common.h"

#include "threads.h"

#include "debug.h"

#include "decode.h"

#include "detect.h"

#include "detect-parse.h"

#include "detect-engine.h"

#include "detect-engine-mpm.h"

#include "detect-engine-state.h"

#include "flow.h"

#include "flow-var.h"

#include "flow-util.h"

#include "util-debug.h"

#include "util-unittest.h"

#include "util-unittest-helper.h"

#include "app-layer.h"

#include "app-layer-parser.h"

#include "app-layer-ssl.h"

#include "detect-tls-version.h"

#include "stream-tcp.h"

/**

 * \brief Regex for parsing "id" option, matching number or "number"

 */

#define PARSE_REGEX  "^\\s*([A-z0-9\\.]+|\"[A-z0-9\\.]+\")\\s*$"

static DetectParseRegex parse_regex;

static int DetectTlsVersionMatch (DetectEngineThreadCtx *,

        Flow *, uint8_t, void *, void *,

        const Signature *, const SigMatchCtx *);

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

#ifdef UNITTESTS

static void DetectTlsVersionRegisterTests(void);

#endif

static void DetectTlsVersionFree(DetectEngineCtx *, void *);

static int g_tls_generic_list_id = 0;

/**

 * \brief Registration function for keyword: tls.version

 */

void DetectTlsVersionRegister (void)

{

    sigmatch_table[DETECT_AL_TLS_VERSION].name = "tls.version";

    sigmatch_table[DETECT_AL_TLS_VERSION].desc = "match on TLS/SSL version";

    sigmatch_table[DETECT_AL_TLS_VERSION].url = "/rules/tls-keywords.html#tls-version";

    sigmatch_table[DETECT_AL_TLS_VERSION].AppLayerTxMatch = DetectTlsVersionMatch;

    sigmatch_table[DETECT_AL_TLS_VERSION].Setup = DetectTlsVersionSetup;

    sigmatch_table[DETECT_AL_TLS_VERSION].Free  = DetectTlsVersionFree;

#ifdef UNITTESTS

    sigmatch_table[DETECT_AL_TLS_VERSION].RegisterTests = DetectTlsVersionRegisterTests;

#endif

    DetectSetupParseRegexes(PARSE_REGEX, &parse_regex);

    g_tls_generic_list_id = DetectBufferTypeRegister("tls_generic");

}

/**

 * \brief match the specified version on a tls session

 *

 * \param t pointer to thread vars

 * \param det_ctx pointer to the pattern matcher thread

 * \param p pointer to the current packet

 * \param m pointer to the sigmatch that we will cast into DetectTlsVersionData

 *

 * \retval 0 no match

 * \retval 1 match

 */

static int DetectTlsVersionMatch (DetectEngineThreadCtx *det_ctx,

        Flow *f, uint8_t flags, void *state, void *txv,

        const Signature *s, const SigMatchCtx *m)

{

    SCEnter();

    const DetectTlsVersionData *tls_data = (const DetectTlsVersionData *)m;

    SSLState *ssl_state = (SSLState *)state;

    if (ssl_state == NULL) {

        SCLogDebug("no tls state, no match");

        SCReturnInt(0);

    }

    int ret = 0;

    uint16_t version = 0;

    SCLogDebug("looking for tls_data->ver 0x%02X (flags 0x%02X)", tls_data->ver, flags);

    if (flags & STREAM_TOCLIENT) {

        version = ssl_state->server_connp.version;

        SCLogDebug("server (toclient) version is 0x%02X", version);

    } else if (flags & STREAM_TOSERVER) {

        version =  ssl_state->client_connp.version;

        SCLogDebug("client (toserver) version is 0x%02X", version);

    }

    if ((tls_data->flags & DETECT_TLS_VERSION_FLAG_RAW) == 0) {

        /* Match all TLSv1.3 drafts as TLSv1.3 */

        if (((version >> 8) & 0xff) == 0x7f) {

            version = TLS_VERSION_13;

        }

    }

    if (tls_data->ver == version) {

        ret = 1;

    }

    SCReturnInt(ret);

}

/**

 * \brief This function is used to parse IPV4 ip_id passed via keyword: "id"

 *

 * \param de_ctx Pointer to the detection engine context

 * \param idstr Pointer to the user provided id option

 *

 * \retval id_d pointer to DetectTlsVersionData on success

 * \retval NULL on failure

 */

static DetectTlsVersionData *DetectTlsVersionParse (DetectEngineCtx *de_ctx, const char *str)

{

    uint16_t temp;

    DetectTlsVersionData *tls = NULL;

    int ret = 0, res = 0;

    size_t pcre2len;

    ret = DetectParsePcreExec(&parse_regex, str, 0, 0);

    if (ret < 1 || ret > 3) {

        SCLogError(SC_ERR_PCRE_MATCH, "invalid tls.version option");

        goto error;

    }

    if (ret > 1) {

        char ver_ptr[64];

        char *tmp_str;

        pcre2len = sizeof(ver_ptr);

        res = pcre2_substring_copy_bynumber(

                parse_regex.match, 1, (PCRE2_UCHAR8 *)ver_ptr, &pcre2len);

        if (res < 0) {

            SCLogError(SC_ERR_PCRE_GET_SUBSTRING, "pcre2_substring_copy_bynumber failed");

            goto error;

        }

        /* We have a correct id option */

        tls = SCCalloc(1, sizeof(DetectTlsVersionData));

        if (unlikely(tls == NULL))

            goto error;

        tmp_str = ver_ptr;

        /* Let's see if we need to scape "'s */

        if (tmp_str[0] == '"')

        {

            tmp_str[strlen(tmp_str) - 1] = '\0';

            tmp_str += 1;

        }

        if (strncmp("1.0", tmp_str, 3) == 0) {

            temp = TLS_VERSION_10;

        } else if (strncmp("1.1", tmp_str, 3) == 0) {

            temp = TLS_VERSION_11;

        } else if (strncmp("1.2", tmp_str, 3) == 0) {

            temp = TLS_VERSION_12;

        } else if (strncmp("1.3", tmp_str, 3) == 0) {

            temp = TLS_VERSION_13;

        } else if ((strncmp("0x", tmp_str, 2) == 0) && (strlen(str) == 6)) {

            temp = (uint16_t)strtol(tmp_str, NULL, 0);

            tls->flags |= DETECT_TLS_VERSION_FLAG_RAW;

        } else {

            SCLogError(SC_ERR_INVALID_VALUE, "Invalid value");

            goto error;

        }

        tls->ver = temp;

        SCLogDebug("will look for tls %"PRIu16"", tls->ver);

    }

    return tls;

error:

    if (tls != NULL)

        DetectTlsVersionFree(de_ctx, tls);

    return NULL;

}

/**

 * \brief this function is used to add the parsed "id" option

 * \brief into the current signature

 *

 * \param de_ctx pointer to the Detection Engine Context

 * \param s pointer to the Current Signature

 * \param idstr pointer to the user provided "id" option

 *

 * \retval 0 on Success

 * \retval -1 on Failure

 */

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

{

    DetectTlsVersionData *tls = NULL;

    SigMatch *sm = NULL;

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

        return -1;

    tls = DetectTlsVersionParse(de_ctx, str);

    if (tls == NULL)

        goto error;

    /* Okay so far so good, lets get this into a SigMatch

     * and put it in the Signature. */

    sm = SigMatchAlloc();

    if (sm == NULL)

        goto error;

    sm->type = DETECT_AL_TLS_VERSION;

    sm->ctx = (void *)tls;

    SigMatchAppendSMToList(s, sm, g_tls_generic_list_id);

    return 0;

error:

    if (tls != NULL)

        DetectTlsVersionFree(de_ctx, tls);

    if (sm != NULL)

        SCFree(sm);

    return -1;

}

/**

 * \brief this function will free memory associated with DetectTlsVersionData

 *

 * \param id_d pointer to DetectTlsVersionData

 */

static void DetectTlsVersionFree(DetectEngineCtx *de_ctx, void *ptr)

{

    DetectTlsVersionData *id_d = (DetectTlsVersionData *)ptr;

    SCFree(id_d);

}

#ifdef UNITTESTS

#include "tests/detect-tls-version.c"

#endif