/* Copyright (C) 2007-2021 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 Anoop Saldanha <anoopsaldanha@gmail.com>

 *

 * Implements support for the http_client_body 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-state.h"

#include "detect-engine-prefilter.h"

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

#include "detect-content.h"

#include "detect-pcre.h"

// PrefilterMpmFiledata

#include "detect-file-data.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-client-body.h"

#include "stream-tcp.h"

#include "util-profiling.h"

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

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

#ifdef UNITTESTS

static void DetectHttpClientBodyRegisterTests(void);

#endif

static void DetectHttpClientBodySetupCallback(const DetectEngineCtx *de_ctx,

                                              Signature *s);

static int g_http_client_body_buffer_id = 0;

static uint8_t DetectEngineInspectBufferHttpBody(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);

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

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

/**

 * \brief Registers the keyword handlers for the "http_client_body" keyword.

 */

void DetectHttpClientBodyRegister(void)

{

    /* http_client_body content modifier */

    sigmatch_table[DETECT_AL_HTTP_CLIENT_BODY].name = "http_client_body";

    sigmatch_table[DETECT_AL_HTTP_CLIENT_BODY].desc = "content modifier to match only on HTTP request-body";

    sigmatch_table[DETECT_AL_HTTP_CLIENT_BODY].url = "/rules/http-keywords.html#http-client-body";

    sigmatch_table[DETECT_AL_HTTP_CLIENT_BODY].Setup = DetectHttpClientBodySetup;

#ifdef UNITTESTS

    sigmatch_table[DETECT_AL_HTTP_CLIENT_BODY].RegisterTests = DetectHttpClientBodyRegisterTests;

#endif

    sigmatch_table[DETECT_AL_HTTP_CLIENT_BODY].flags |= SIGMATCH_NOOPT ;

    sigmatch_table[DETECT_AL_HTTP_CLIENT_BODY].flags |= SIGMATCH_INFO_CONTENT_MODIFIER;

    sigmatch_table[DETECT_AL_HTTP_CLIENT_BODY].alternative = DETECT_HTTP_REQUEST_BODY;

    /* http.request_body sticky buffer */

    sigmatch_table[DETECT_HTTP_REQUEST_BODY].name = "http.request_body";

    sigmatch_table[DETECT_HTTP_REQUEST_BODY].desc = "sticky buffer to match the HTTP request body buffer";

    sigmatch_table[DETECT_HTTP_REQUEST_BODY].url = "/rules/http-keywords.html#http-client-body";

    sigmatch_table[DETECT_HTTP_REQUEST_BODY].Setup = DetectHttpClientBodySetupSticky;

    sigmatch_table[DETECT_HTTP_REQUEST_BODY].flags |= SIGMATCH_NOOPT;

    sigmatch_table[DETECT_HTTP_REQUEST_BODY].flags |= SIGMATCH_INFO_STICKY_BUFFER;

    DetectAppLayerInspectEngineRegister2("http_client_body", ALPROTO_HTTP1, SIG_FLAG_TOSERVER,

            HTP_REQUEST_BODY, DetectEngineInspectBufferHttpBody, NULL);

    DetectAppLayerMpmRegister2("http_client_body", SIG_FLAG_TOSERVER, 2,

            PrefilterMpmHttpRequestBodyRegister, NULL, ALPROTO_HTTP1, HTP_REQUEST_BODY);

    DetectAppLayerInspectEngineRegister2("http_client_body", ALPROTO_HTTP2, SIG_FLAG_TOSERVER,

            HTTP2StateDataClient, DetectEngineInspectFiledata, NULL);

    DetectAppLayerMpmRegister2("http_client_body", SIG_FLAG_TOSERVER, 2,

            PrefilterMpmFiledataRegister, NULL, ALPROTO_HTTP2, HTTP2StateDataClient);

    DetectBufferTypeSetDescriptionByName("http_client_body",

            "http request body");

    DetectBufferTypeRegisterSetupCallback("http_client_body",

            DetectHttpClientBodySetupCallback);

    g_http_client_body_buffer_id = DetectBufferTypeGetByName("http_client_body");

}

static void DetectHttpClientBodySetupCallback(const DetectEngineCtx *de_ctx,

                                              Signature *s)

{

    SCLogDebug("callback invoked by %u", s->id);

    AppLayerHtpEnableRequestBodyCallback();

    /* client body needs to be inspected in sync with stream if possible */

    s->init_data->init_flags |= SIG_FLAG_INIT_NEED_FLUSH;

}

/**

 * \brief The setup function for the http_client_body keyword for a signature.

 *

 * \param de_ctx Pointer to the detection engine context.

 * \param s      Pointer to signature for the current Signature being parsed

 *               from the rules.

 * \param m      Pointer to the head of the SigMatchs for the current rule

 *               being parsed.

 * \param arg    Pointer to the string holding the keyword value.

 *

 * \retval  0 On success

 * \retval -1 On failure

 */

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

{

    return DetectEngineContentModifierBufferSetup(de_ctx, s, arg, DETECT_AL_HTTP_CLIENT_BODY,

            g_http_client_body_buffer_id, ALPROTO_HTTP1);

}

/**

 * \brief this function setup the http.request_body 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 DetectHttpClientBodySetupSticky(DetectEngineCtx *de_ctx, Signature *s, const char *str)

{

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

        return -1;

    if (DetectSignatureSetAppProto(s, ALPROTO_HTTP) < 0)

        return -1;

    return 0;

}

static inline HtpBody *GetRequestBody(htp_tx_t *tx)

{

    HtpTxUserData *htud = (HtpTxUserData *)htp_tx_get_user_data(tx);

    if (htud == NULL) {

        SCLogDebug("no htud");

        return NULL;

    }

    return &htud->request_body;

}

typedef struct PrefilterMpmHttpRequestBody {

    int list_id;

    int base_list_id;

    const MpmCtx *mpm_ctx;

    const DetectEngineTransforms *transforms;

} PrefilterMpmHttpRequestBody;

static void PrefilterMpmHttpRequestBodyFree(void *ptr)

{

    SCFree(ptr);

}

static inline InspectionBuffer *HttpRequestBodyXformsGetDataCallback(DetectEngineThreadCtx *det_ctx,

        const DetectEngineTransforms *transforms, const int list_id, InspectionBuffer *base_buffer)

{

    InspectionBuffer *buffer = InspectionBufferGet(det_ctx, list_id);

    if (buffer->inspect != NULL)

        return buffer;

    InspectionBufferSetup(det_ctx, list_id, buffer, base_buffer->inspect, base_buffer->inspect_len);

    buffer->inspect_offset = base_buffer->inspect_offset;

    InspectionBufferApplyTransforms(buffer, transforms);

    SCLogDebug("xformed buffer %p size %u", buffer, buffer->inspect_len);

    SCReturnPtr(buffer, "InspectionBuffer");

}

static InspectionBuffer *HttpRequestBodyGetDataCallback(DetectEngineThreadCtx *det_ctx,

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

        const int list_id, const int base_id)

{

    SCEnter();

    InspectionBuffer *buffer = InspectionBufferGet(det_ctx, base_id);

    if (base_id != list_id && buffer->inspect != NULL)

        return HttpRequestBodyXformsGetDataCallback(det_ctx, transforms, list_id, buffer);

    else if (buffer->inspect != NULL)

        return buffer;

    htp_tx_t *tx = txv;

    HtpState *htp_state = f->alstate;

    const uint8_t flags = flow_flags;

    HtpBody *body = GetRequestBody(tx);

    if (body == NULL) {

        return NULL;

    }

    /* no new data */

    if (body->body_inspected == body->content_len_so_far) {

        SCLogDebug("no new data");

        return NULL;

    }

    HtpBodyChunk *cur = body->first;

    if (cur == NULL) {

        SCLogDebug("No http chunks to inspect for this transaction");

        return NULL;

    }

    SCLogDebug("request.body_limit %u request_body.content_len_so_far %" PRIu64

               ", request.inspect_min_size %" PRIu32 ", EOF %s, progress > body? %s",

            htp_state->cfg->request.body_limit, body->content_len_so_far,

            htp_state->cfg->request.inspect_min_size, flags & STREAM_EOF ? "true" : "false",

            (AppLayerParserGetStateProgress(IPPROTO_TCP, ALPROTO_HTTP1, tx, flags) >

                    HTP_REQUEST_BODY)

                    ? "true"

                    : "false");

    if (!htp_state->cfg->http_body_inline) {

        /* inspect the body if the transfer is complete or we have hit

        * our body size limit */

        if ((htp_state->cfg->request.body_limit == 0 ||

                    body->content_len_so_far < htp_state->cfg->request.body_limit) &&

                body->content_len_so_far < htp_state->cfg->request.inspect_min_size &&

                !(AppLayerParserGetStateProgress(IPPROTO_TCP, ALPROTO_HTTP1, tx, flags) >

                        HTP_REQUEST_BODY) &&

                !(flags & STREAM_EOF)) {

            SCLogDebug("we still haven't seen the entire request body.  "

                       "Let's defer body inspection till we see the "

                       "entire body.");

            return NULL;

        }

    }

    /* get the inspect buffer

     *

     * make sure that we have at least the configured inspect_win size.

     * If we have more, take at least 1/4 of the inspect win size before

     * the new data.

     */

    uint64_t offset = 0;

    if (body->body_inspected > htp_state->cfg->request.inspect_min_size) {

        BUG_ON(body->content_len_so_far < body->body_inspected);

        uint64_t inspect_win = body->content_len_so_far - body->body_inspected;

        SCLogDebug("inspect_win %"PRIu64, inspect_win);

        if (inspect_win < htp_state->cfg->request.inspect_window) {

            uint64_t inspect_short = htp_state->cfg->request.inspect_window - inspect_win;

            if (body->body_inspected < inspect_short)

                offset = 0;

            else

                offset = body->body_inspected - inspect_short;

        } else {

            offset = body->body_inspected - (htp_state->cfg->request.inspect_window / 4);

        }

    }

    const uint8_t *data;

    uint32_t data_len;

    StreamingBufferGetDataAtOffset(body->sb,

            &data, &data_len, offset);

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

    buffer->inspect_offset = offset;

    body->body_inspected = body->content_len_so_far;

    SCLogDebug("body->body_inspected now: %" PRIu64, body->body_inspected);

    if (base_id != list_id) {

        buffer = HttpRequestBodyXformsGetDataCallback(det_ctx, transforms, list_id, buffer);

    }

    SCReturnPtr(buffer, "InspectionBuffer");

}

static uint8_t DetectEngineInspectBufferHttpBody(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)

{

    bool eof =

            (AppLayerParserGetStateProgress(f->proto, f->alproto, txv, flags) > engine->progress);

    const InspectionBuffer *buffer = HttpRequestBodyGetDataCallback(

            det_ctx, engine->v2.transforms, f, flags, txv, engine->sm_list, engine->sm_list_base);

    if (buffer == NULL || buffer->inspect == NULL) {

        return eof ? DETECT_ENGINE_INSPECT_SIG_CANT_MATCH : DETECT_ENGINE_INSPECT_SIG_NO_MATCH;

    }

    const uint32_t data_len = buffer->inspect_len;

    const uint8_t *data = buffer->inspect;

    const uint64_t offset = buffer->inspect_offset;

    uint8_t ci_flags = eof ? DETECT_CI_FLAGS_END : 0;

    ci_flags |= (offset == 0 ? DETECT_CI_FLAGS_START : 0);

    ci_flags |= buffer->flags;

    det_ctx->discontinue_matching = 0;

    det_ctx->buffer_offset = 0;

    det_ctx->inspection_recursion_counter = 0;

    /* Inspect all the uricontents fetched on each

     * transaction at the app layer */

    int r = DetectEngineContentInspection(de_ctx, det_ctx, s, engine->smd, NULL, f, (uint8_t *)data,

            data_len, offset, ci_flags, DETECT_ENGINE_CONTENT_INSPECTION_MODE_STATE);

    if (r == 1) {

        return DETECT_ENGINE_INSPECT_SIG_MATCH;

    }

    if (flags & STREAM_TOSERVER) {

        if (AppLayerParserGetStateProgress(IPPROTO_TCP, ALPROTO_HTTP1, txv, flags) >

                HTP_REQUEST_BODY)

            return DETECT_ENGINE_INSPECT_SIG_CANT_MATCH;

    } else {

        if (AppLayerParserGetStateProgress(IPPROTO_TCP, ALPROTO_HTTP1, txv, flags) >

                HTP_RESPONSE_BODY)

            return DETECT_ENGINE_INSPECT_SIG_CANT_MATCH;

    }

    return DETECT_ENGINE_INSPECT_SIG_NO_MATCH;

}

/** \brief HTTP Request body callback

 *

 *  \param det_ctx detection engine thread ctx

 *  \param pectx inspection context

 *  \param p packet to inspect

 *  \param f flow to inspect

 *  \param txv tx to inspect

 *  \param idx transaction id

 *  \param flags STREAM_* flags including direction

 */

static void PrefilterTxHttpRequestBody(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 PrefilterMpmHttpRequestBody *ctx = (const PrefilterMpmHttpRequestBody *)pectx;

    const MpmCtx *mpm_ctx = ctx->mpm_ctx;

    const int list_id = ctx->list_id;

    InspectionBuffer *buffer = HttpRequestBodyGetDataCallback(

            det_ctx, ctx->transforms, f, flags, txv, list_id, ctx->base_list_id);

    if (buffer == NULL)

        return;

    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);

    }

}

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

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

{

    PrefilterMpmHttpRequestBody *pectx = SCCalloc(1, sizeof(*pectx));

    if (pectx == NULL)

        return -1;

    pectx->list_id = list_id;

    pectx->base_list_id = mpm_reg->sm_list_base;

    SCLogDebug("list_id %d base_list_id %d", list_id, pectx->base_list_id);

    pectx->mpm_ctx = mpm_ctx;

    pectx->transforms = &mpm_reg->transforms;

    return PrefilterAppendTxEngine(de_ctx, sgh, PrefilterTxHttpRequestBody, mpm_reg->app_v2.alproto,

            mpm_reg->app_v2.tx_min_progress, pectx, PrefilterMpmHttpRequestBodyFree,

            mpm_reg->pname);

}

#ifdef UNITTESTS

#include "detect-engine-alert.h"

#include "tests/detect-http-client-body.c"

#endif /* UNITTESTS */

/**

 * @}

 */