/* Copyright (C) 2007-2017 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 Victor Julien <victor@inliniac.net>

 *

 * Implements support http_header_names

 */

#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"

#include "detect-http-header-common.h"

#include "detect-http-header-names.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 "util-print.h"

#include "app-layer.h"

#include "app-layer-parser.h"

#include "app-layer-htp.h"

#include "detect-http-header.h"

#include "stream-tcp.h"

#define KEYWORD_NAME "http.header_names"

#define KEYWORD_NAME_LEGACY "http_header_names"

#define KEYWORD_DOC "http-keywords.html#http-header-names"

#define BUFFER_NAME "http_header_names"

#define BUFFER_DESC "http header names"

static int g_buffer_id = 0;

static int g_keyword_thread_id = 0;

#define BUFFER_SIZE_STEP    256

static HttpHeaderThreadDataConfig g_td_config = { BUFFER_SIZE_STEP };

static uint8_t *GetBufferForTX(

        htp_tx_t *tx, DetectEngineThreadCtx *det_ctx, Flow *f, uint8_t flags, uint32_t *buffer_len)

{

    *buffer_len = 0;

    HttpHeaderThreadData *hdr_td = NULL;

    HttpHeaderBuffer *buf =

            HttpHeaderGetBufferSpace(det_ctx, f, flags, g_keyword_thread_id, &hdr_td);

    if (unlikely(buf == NULL)) {

        return NULL;

    }

    htp_table_t *headers;

    if (flags & STREAM_TOSERVER) {

        if (AppLayerParserGetStateProgress(IPPROTO_TCP, ALPROTO_HTTP1, tx, flags) <=

                HTP_REQUEST_HEADERS)

            return NULL;

        headers = tx->request_headers;

    } else {

        if (AppLayerParserGetStateProgress(IPPROTO_TCP, ALPROTO_HTTP1, tx, flags) <=

                HTP_RESPONSE_HEADERS)

            return NULL;

        headers = tx->response_headers;

    }

    if (headers == NULL)

        return NULL;

    /* fill the buffer. \r\nName1\r\nName2\r\n\r\n */

    size_t i = 0;

    size_t no_of_headers = htp_table_size(headers);

    for (; i < no_of_headers; i++) {

        htp_header_t *h = htp_table_get_index(headers, i, NULL);

        size_t size = bstr_size(h->name) + 2; // for \r\n

        if (i == 0)

            size += 2;

        if (i + 1 == no_of_headers)

            size += 2;

        SCLogDebug("size %"PRIuMAX" + buf->len %u vs buf->size %u",

                (uintmax_t)size, buf->len, buf->size);

        if (size + buf->len > buf->size) {

            if (HttpHeaderExpandBuffer(hdr_td, buf, size) != 0) {

                return NULL;

            }

        }

        /* start with a \r\n */

        if (i == 0) {

            buf->buffer[buf->len++] = '\r';

            buf->buffer[buf->len++] = '\n';

        }

        memcpy(buf->buffer + buf->len, bstr_ptr(h->name), bstr_size(h->name));

        buf->len += bstr_size(h->name);

        buf->buffer[buf->len++] = '\r';

        buf->buffer[buf->len++] = '\n';

        /* end with an extra \r\n */

        if (i + 1 == no_of_headers) {

            buf->buffer[buf->len++] = '\r';

            buf->buffer[buf->len++] = '\n';

        }

    }

    *buffer_len = buf->len;

    return buf->buffer;

}

static InspectionBuffer *GetBuffer1ForTX(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 rawdata_len = 0;

        uint8_t *rawdata = GetBufferForTX(txv, det_ctx, f, flow_flags, &rawdata_len);

        if (rawdata_len == 0)

            return NULL;

        InspectionBufferSetup(det_ctx, list_id, buffer, rawdata, rawdata_len);

        InspectionBufferApplyTransforms(buffer, transforms);

    }

    return buffer;

}

static InspectionBuffer *GetBuffer2ForTX(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_header_names(txv, flow_flags, &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;

}

/**

 * \brief The setup function for the http.header_names 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.

 */

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

{

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

        return -1;

    if (DetectSignatureSetAppProto(s, ALPROTO_HTTP) < 0)

        return -1;

    return 0;

}

/**

 * \brief Registers the keyword handlers for the "http.header_names" keyword.

 */

void DetectHttpHeaderNamesRegister(void)

{

    sigmatch_table[DETECT_AL_HTTP_HEADER_NAMES].name = KEYWORD_NAME;

    sigmatch_table[DETECT_AL_HTTP_HEADER_NAMES].alias = KEYWORD_NAME_LEGACY;

    sigmatch_table[DETECT_AL_HTTP_HEADER_NAMES].desc = BUFFER_NAME " sticky buffer";

    sigmatch_table[DETECT_AL_HTTP_HEADER_NAMES].url = "/rules/" KEYWORD_DOC;

    sigmatch_table[DETECT_AL_HTTP_HEADER_NAMES].Setup = DetectHttpHeaderNamesSetup;

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

    /* http1 */

    DetectAppLayerMpmRegister2(BUFFER_NAME, SIG_FLAG_TOSERVER, 2, PrefilterGenericMpmRegister,

            GetBuffer1ForTX, ALPROTO_HTTP1, HTP_REQUEST_HEADERS);

    DetectAppLayerMpmRegister2(BUFFER_NAME, SIG_FLAG_TOCLIENT, 2, PrefilterGenericMpmRegister,

            GetBuffer1ForTX, ALPROTO_HTTP1, HTP_RESPONSE_HEADERS);

    DetectAppLayerInspectEngineRegister2(BUFFER_NAME, ALPROTO_HTTP1, SIG_FLAG_TOSERVER,

            HTP_REQUEST_HEADERS, DetectEngineInspectBufferGeneric, GetBuffer1ForTX);

    DetectAppLayerInspectEngineRegister2(BUFFER_NAME, ALPROTO_HTTP1, SIG_FLAG_TOCLIENT,

            HTP_RESPONSE_HEADERS, DetectEngineInspectBufferGeneric, GetBuffer1ForTX);

    /* http2 */

    DetectAppLayerMpmRegister2(BUFFER_NAME, SIG_FLAG_TOSERVER, 2, PrefilterGenericMpmRegister,

            GetBuffer2ForTX, ALPROTO_HTTP2, HTTP2StateDataClient);

    DetectAppLayerMpmRegister2(BUFFER_NAME, SIG_FLAG_TOCLIENT, 2, PrefilterGenericMpmRegister,

            GetBuffer2ForTX, ALPROTO_HTTP2, HTTP2StateDataServer);

    DetectAppLayerInspectEngineRegister2(BUFFER_NAME, ALPROTO_HTTP2, SIG_FLAG_TOSERVER,

            HTTP2StateDataClient, DetectEngineInspectBufferGeneric, GetBuffer2ForTX);

    DetectAppLayerInspectEngineRegister2(BUFFER_NAME, ALPROTO_HTTP2, SIG_FLAG_TOCLIENT,

            HTTP2StateDataServer, DetectEngineInspectBufferGeneric, GetBuffer2ForTX);

    DetectBufferTypeSetDescriptionByName(BUFFER_NAME,

            BUFFER_DESC);

    g_buffer_id = DetectBufferTypeGetByName(BUFFER_NAME);

    g_keyword_thread_id = DetectRegisterThreadCtxGlobalFuncs(KEYWORD_NAME,

            HttpHeaderThreadDataInit, &g_td_config, HttpHeaderThreadDataFree);

    SCLogDebug("keyword %s registered. Thread id %d. "

            "Buffer %s registered. Buffer id %d",

            KEYWORD_NAME, g_keyword_thread_id,

            BUFFER_NAME, g_buffer_id);

}