/* Copyright (C) 2007-2019 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.

 */

/**

 * \ingroup httplayer

 *

 * @{

 */

/**

 * \file

 *

 * \author Brian Rectanus <brectanu@gmail.com>

 *

 * Implements the http_method 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 "flow.h"

#include "flow-var.h"

#include "flow-util.h"

#include "util-debug.h"

#include "util-unittest.h"

#include "util-unittest-helper.h"

#include "util-spm.h"

#include "app-layer.h"

#include "app-layer-parser.h"

#include "app-layer-htp.h"

#include "detect-http-method.h"

#include "stream-tcp.h"

static int g_http_method_buffer_id = 0;

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

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

#ifdef UNITTESTS

void DetectHttpMethodRegisterTests(void);

#endif

void DetectHttpMethodFree(void *);

static bool DetectHttpMethodValidateCallback(const Signature *s, const char **sigerror);

static InspectionBuffer *GetData(DetectEngineThreadCtx *det_ctx,

        const DetectEngineTransforms *transforms, Flow *_f,

        const uint8_t _flow_flags, void *txv, const int list_id);

static InspectionBuffer *GetData2(DetectEngineThreadCtx *det_ctx,

        const DetectEngineTransforms *transforms, Flow *_f, const uint8_t _flow_flags, void *txv,

        const int list_id);

/**

 * \brief Registration function for keyword: http_method

 */

void DetectHttpMethodRegister(void)

{

    /* http_method content modifier */

    sigmatch_table[DETECT_AL_HTTP_METHOD].name = "http_method";

    sigmatch_table[DETECT_AL_HTTP_METHOD].desc = "content modifier to match only on the HTTP method-buffer";

    sigmatch_table[DETECT_AL_HTTP_METHOD].url = "/rules/http-keywords.html#http-method";

    sigmatch_table[DETECT_AL_HTTP_METHOD].Match = NULL;

    sigmatch_table[DETECT_AL_HTTP_METHOD].Setup = DetectHttpMethodSetup;

#ifdef UNITTESTS

    sigmatch_table[DETECT_AL_HTTP_METHOD].RegisterTests = DetectHttpMethodRegisterTests;

#endif

    sigmatch_table[DETECT_AL_HTTP_METHOD].flags |= SIGMATCH_NOOPT|SIGMATCH_INFO_CONTENT_MODIFIER;

    sigmatch_table[DETECT_AL_HTTP_METHOD].alternative = DETECT_HTTP_METHOD;

    /* http.method sticky buffer */

    sigmatch_table[DETECT_HTTP_METHOD].name = "http.method";

    sigmatch_table[DETECT_HTTP_METHOD].desc = "sticky buffer to match specifically and only on the HTTP method buffer";

    sigmatch_table[DETECT_HTTP_METHOD].url = "/rules/http-keywords.html#http-method";

    sigmatch_table[DETECT_HTTP_METHOD].Setup = DetectHttpMethodSetupSticky;

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

    DetectAppLayerInspectEngineRegister2("http_method", ALPROTO_HTTP1, SIG_FLAG_TOSERVER,

            HTP_REQUEST_LINE, DetectEngineInspectBufferGeneric, GetData);

    DetectAppLayerMpmRegister2("http_method", SIG_FLAG_TOSERVER, 4, PrefilterGenericMpmRegister,

            GetData, ALPROTO_HTTP1, HTP_REQUEST_LINE);

    DetectAppLayerInspectEngineRegister2("http_method", ALPROTO_HTTP2, SIG_FLAG_TOSERVER,

            HTTP2StateDataClient, DetectEngineInspectBufferGeneric, GetData2);

    DetectAppLayerMpmRegister2("http_method", SIG_FLAG_TOSERVER, 4, PrefilterGenericMpmRegister,

            GetData2, ALPROTO_HTTP2, HTTP2StateDataClient);

    DetectBufferTypeSetDescriptionByName("http_method",

            "http request method");

    DetectBufferTypeRegisterValidateCallback("http_method",

            DetectHttpMethodValidateCallback);

    g_http_method_buffer_id = DetectBufferTypeGetByName("http_method");

    SCLogDebug("registering http_method rule option");

}

/**

 * \brief This function is used to add the parsed "http_method" option

 *        into the current signature.

 *

 * \param de_ctx Pointer to the Detection Engine Context.

 * \param s      Pointer to the Current Signature.

 * \param str    Pointer to the user provided option string.

 *

 * \retval  0 on Success.

 * \retval -1 on Failure.

 */

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

{

    return DetectEngineContentModifierBufferSetup(

            de_ctx, s, str, DETECT_AL_HTTP_METHOD, g_http_method_buffer_id, ALPROTO_HTTP1);

}

/**

 * \brief this function setup the http.method 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

 */

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

{

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

        return -1;

    if (DetectSignatureSetAppProto(s, ALPROTO_HTTP) < 0)

        return -1;

    return 0;

}

/**

 *  \retval 1 valid

 *  \retval 0 invalid

 */

static bool DetectHttpMethodValidateCallback(const Signature *s, const char **sigerror)

{

    for (uint32_t x = 0; x < s->init_data->buffer_index; x++) {

        if (s->init_data->buffers[x].id != (uint32_t)g_http_method_buffer_id)

            continue;

        const SigMatch *sm = s->init_data->buffers[x].head;

        for (; sm != NULL; sm = sm->next) {

            if (sm->type != DETECT_CONTENT)

                continue;

            const DetectContentData *cd = (const DetectContentData *)sm->ctx;

            if (cd->content && cd->content_len) {

                if (cd->content[cd->content_len - 1] == 0x20) {

                    *sigerror = "http_method pattern with trailing space";

                    SCLogError("%s", *sigerror);

                    return false;

                } else if (cd->content[0] == 0x20) {

                    *sigerror = "http_method pattern with leading space";

                    SCLogError("%s", *sigerror);

                    return false;

                } else if (cd->content[cd->content_len - 1] == 0x09) {

                    *sigerror = "http_method pattern with trailing tab";

                    SCLogError("%s", *sigerror);

                    return false;

                } else if (cd->content[0] == 0x09) {

                    *sigerror = "http_method pattern with leading tab";

                    SCLogError("%s", *sigerror);

                    return false;

                }

            }

        }

    }

    return true;

}

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) {

        htp_tx_t *tx = (htp_tx_t *)txv;

        if (tx->request_method == NULL)

            return NULL;

        const uint32_t data_len = bstr_len(tx->request_method);

        const uint8_t *data = bstr_ptr(tx->request_method);

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

        InspectionBufferApplyTransforms(buffer, transforms);

    }

    return buffer;

}

static InspectionBuffer *GetData2(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) {

        uint32_t b_len = 0;

        const uint8_t *b = NULL;

        if (rs_http2_tx_get_method(txv, &b, &b_len) != 1)

            return NULL;

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

            return NULL;

        InspectionBufferSetup(det_ctx, list_id, buffer, b, b_len);

        InspectionBufferApplyTransforms(buffer, transforms);

    }

    return buffer;

}

#ifdef UNITTESTS

#include "tests/detect-http-method.c"

#endif

/**

 * @}

 */