/* Copyright (C) 2007-2018 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_user_agent 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-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 "stream-tcp.h"

#include "detect-http-ua.h"

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

#ifdef UNITTESTS

static void DetectHttpUARegisterTests(void);

#endif

static int g_http_ua_buffer_id = 0;

static int g_http2_thread_id = 0;

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

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 Registers the keyword handlers for the "http_user_agent" keyword.

 */

void DetectHttpUARegister(void)

{

    /* http_user_agent content modifier */

    sigmatch_table[DETECT_AL_HTTP_USER_AGENT].name = "http_user_agent";

    sigmatch_table[DETECT_AL_HTTP_USER_AGENT].desc = "content modifier to match only on the HTTP User-Agent header";

    sigmatch_table[DETECT_AL_HTTP_USER_AGENT].url = "/rules/http-keywords.html#http-user-agent";

    sigmatch_table[DETECT_AL_HTTP_USER_AGENT].Setup = DetectHttpUASetup;

#ifdef UNITTESTS

    sigmatch_table[DETECT_AL_HTTP_USER_AGENT].RegisterTests = DetectHttpUARegisterTests;

#endif

    sigmatch_table[DETECT_AL_HTTP_USER_AGENT].flags |= SIGMATCH_NOOPT;

    sigmatch_table[DETECT_AL_HTTP_USER_AGENT].flags |= SIGMATCH_INFO_CONTENT_MODIFIER;

    sigmatch_table[DETECT_AL_HTTP_USER_AGENT].alternative = DETECT_HTTP_UA;

    /* http.user_agent sticky buffer */

    sigmatch_table[DETECT_HTTP_UA].name = "http.user_agent";

    sigmatch_table[DETECT_HTTP_UA].desc = "sticky buffer to match specifically and only on the HTTP User Agent buffer";

    sigmatch_table[DETECT_HTTP_UA].url = "/rules/http-keywords.html#http-user-agent";

    sigmatch_table[DETECT_HTTP_UA].Setup = DetectHttpUserAgentSetup;

    sigmatch_table[DETECT_HTTP_UA].flags |= SIGMATCH_NOOPT;

    sigmatch_table[DETECT_HTTP_UA].flags |= SIGMATCH_INFO_STICKY_BUFFER;

    DetectAppLayerInspectEngineRegister2("http_user_agent", ALPROTO_HTTP1, SIG_FLAG_TOSERVER,

            HTP_REQUEST_HEADERS, DetectEngineInspectBufferGeneric, GetData);

    DetectAppLayerMpmRegister2("http_user_agent", SIG_FLAG_TOSERVER, 2, PrefilterGenericMpmRegister,

            GetData, ALPROTO_HTTP1, HTP_REQUEST_HEADERS);

    DetectAppLayerInspectEngineRegister2("http_user_agent", ALPROTO_HTTP2, SIG_FLAG_TOSERVER,

            HTTP2StateOpen, DetectEngineInspectBufferGeneric, GetData2);

    DetectAppLayerMpmRegister2("http_user_agent", SIG_FLAG_TOSERVER, 2, PrefilterGenericMpmRegister,

            GetData2, ALPROTO_HTTP2, HTTP2StateOpen);

    DetectBufferTypeSetDescriptionByName("http_user_agent",

            "http user agent");

    g_http2_thread_id = DetectRegisterThreadCtxGlobalFuncs(

            "http_user_agent", SCHttp2ThreadBufDataInit, NULL, SCHttp2ThreadBufDataFree);

    g_http_ua_buffer_id = DetectBufferTypeGetByName("http_user_agent");

}

/**

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

 *

 * \param de_ctx Pointer to the detection engine context.

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

 *               parsed from the rules.

 * \param m      Pointer to the head of the SigMatch 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 DetectHttpUASetup(DetectEngineCtx *de_ctx, Signature *s, const char *arg)

{

    return DetectEngineContentModifierBufferSetup(

            de_ctx, s, arg, DETECT_AL_HTTP_USER_AGENT, g_http_ua_buffer_id, ALPROTO_HTTP1);

}

/**

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

{

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

        return -1;

    if (DetectSignatureSetAppProto(s, ALPROTO_HTTP) < 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) {

        htp_tx_t *tx = (htp_tx_t *)txv;

        if (tx->request_headers == NULL)

            return NULL;

        htp_header_t *h = (htp_header_t *)htp_table_get_c(tx->request_headers,

                "User-Agent");

        if (h == NULL || h->value == NULL) {

            SCLogDebug("HTTP UA header not present in this request");

            return NULL;

        }

        const uint32_t data_len = bstr_len(h->value);

        const uint8_t *data = bstr_ptr(h->value);

        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)

{

    SCEnter();

    InspectionBuffer *buffer = InspectionBufferGet(det_ctx, list_id);

    if (buffer->inspect == NULL) {

        uint32_t b_len = 0;

        const uint8_t *b = NULL;

        void *thread_buf = DetectThreadCtxGetGlobalKeywordThreadCtx(det_ctx, g_http2_thread_id);

        if (thread_buf == NULL)

            return NULL;

        if (SCHttp2TxGetUserAgent(txv, &b, &b_len, thread_buf) != 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-user-agent.c"

#endif /* UNITTESTS */

/**

 * @}

 */