/* 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 "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"

#include "util-print.h"

#define KEYWORD_NAME "http_header_names"
#define KEYWORD_DOC "http-keywords#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_TX_STEP      4
#define BUFFER_SIZE_STEP    256
static HttpHeaderThreadDataConfig g_td_config = { BUFFER_TX_STEP, BUFFER_SIZE_STEP };

static uint8_t *GetBufferForTX(htp_tx_t *tx, uint64_t tx_id,
        DetectEngineCtx *de_ctx, DetectEngineThreadCtx *det_ctx,
        Flow *f, HtpState *htp_state, uint8_t flags,
        uint32_t *buffer_len)
{
    *buffer_len = 0;

    HttpHeaderThreadData *hdr_td = NULL;
    HttpHeaderBuffer *buf = HttpHeaderGetBufferSpaceForTXID(det_ctx, f, flags,
            tx_id, g_keyword_thread_id, &hdr_td);
    if (unlikely(buf == NULL)) {
        return NULL;
    } else if (buf->len > 0) {
        /* already filled buf, reuse */
        *buffer_len = buf->len;
        return buf->buffer;
    }

    htp_table_t *headers;
    if (flags & STREAM_TOSERVER) {
        if (AppLayerParserGetStateProgress(IPPROTO_TCP, ALPROTO_HTTP, tx, flags) <=
                HTP_REQUEST_HEADERS)
            return NULL;
        headers = tx->request_headers;
    } else {
        if (AppLayerParserGetStateProgress(IPPROTO_TCP, ALPROTO_HTTP, 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 %u + buf->len %u vs buf->size %u", (uint)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;
}

/** \brief HTTP Headers Mpm prefilter callback
 *
 *  \param det_ctx detection engine thread ctx
 *  \param p packet to inspect
 *  \param f flow to inspect
 *  \param txv tx to inspect
 *  \param pectx inspection context
 */
static void PrefilterTxHttpRequestHeaderNames(DetectEngineThreadCtx *det_ctx,
        const void *pectx,
        Packet *p, Flow *f, void *txv,
        const uint64_t idx, const uint8_t flags)
{
    SCEnter();

    const MpmCtx *mpm_ctx = (MpmCtx *)pectx;
    htp_tx_t *tx = (htp_tx_t *)txv;

    if (tx->request_headers == NULL)
        return;

    HtpState *htp_state = f->alstate;
    uint32_t buffer_len = 0;
    const uint8_t *buffer = GetBufferForTX(tx, idx,
            NULL, det_ctx, f, htp_state,
            flags, &buffer_len);

    if (buffer_len >= mpm_ctx->minlen) {
        (void)mpm_table[mpm_ctx->mpm_type].Search(mpm_ctx,
                &det_ctx->mtcu, &det_ctx->pmq, buffer, buffer_len);
    }
}
#if 0
static void PrefilterTxHttpRequestTrailers(DetectEngineThreadCtx *det_ctx,
        const void *pectx,
        Packet *p, Flow *f, void *txv,
        const uint64_t idx, const uint8_t flags)
{
    SCEnter();

    const MpmCtx *mpm_ctx = (MpmCtx *)pectx;
    htp_tx_t *tx = (htp_tx_t *)txv;

    if (tx->request_headers == NULL)
        return;
    const HtpTxUserData *htud = (const HtpTxUserData *)htp_tx_get_user_data(tx);
    /* if the request wasn't flagged as having a trailer, we skip */
    if (htud && !htud->request_has_trailers)
        return;

    HtpState *htp_state = f->alstate;
    uint32_t buffer_len = 0;
    const uint8_t *buffer = DetectEngineHHDGetBufferForTX(tx, idx,
                                                    NULL, det_ctx,
                                                    f, htp_state,
                                                    flags,
                                                    &buffer_len);

    if (buffer_len >= mpm_ctx->minlen) {
        (void)mpm_table[mpm_ctx->mpm_type].Search(mpm_ctx,
                &det_ctx->mtcu, &det_ctx->pmq, buffer, buffer_len);
    }
}
#endif
int PrefilterTxHttpRequestHeaderNamesRegister(SigGroupHead *sgh, MpmCtx *mpm_ctx)
{
    SCEnter();

    int r = PrefilterAppendTxEngine(sgh, PrefilterTxHttpRequestHeaderNames,
        ALPROTO_HTTP, HTP_REQUEST_HEADERS,
        mpm_ctx, NULL, KEYWORD_NAME " (request)");
    return r;
#if 0
    if (r != 0)
        return r;
    return PrefilterAppendTxEngine(sgh, PrefilterTxHttpRequestTrailers,
        ALPROTO_HTTP, HTP_REQUEST_TRAILER,
        mpm_ctx, NULL, "http_header (request)");
#endif
}

/** \brief HTTP Headers Mpm prefilter callback
 *
 *  \param det_ctx detection engine thread ctx
 *  \param p packet to inspect
 *  \param f flow to inspect
 *  \param txv tx to inspect
 *  \param pectx inspection context
 */
static void PrefilterTxHttpResponseHeaderNames(DetectEngineThreadCtx *det_ctx,
        const void *pectx,
        Packet *p, Flow *f, void *txv,
        const uint64_t idx, const uint8_t flags)
{
    SCEnter();

    const MpmCtx *mpm_ctx = (MpmCtx *)pectx;
    htp_tx_t *tx = (htp_tx_t *)txv;

    if (tx->response_headers == NULL)
        return;

    HtpState *htp_state = f->alstate;
    uint32_t buffer_len = 0;
    const uint8_t *buffer = GetBufferForTX(tx, idx, NULL, det_ctx,
            f, htp_state, flags, &buffer_len);

    if (buffer_len >= mpm_ctx->minlen) {
        (void)mpm_table[mpm_ctx->mpm_type].Search(mpm_ctx,
                &det_ctx->mtcu, &det_ctx->pmq, buffer, buffer_len);
    }
}
#if 0
static void PrefilterTxHttpResponseTrailers(DetectEngineThreadCtx *det_ctx,
        const void *pectx,
        Packet *p, Flow *f, void *txv,
        const uint64_t idx, const uint8_t flags)
{
    SCEnter();

    const MpmCtx *mpm_ctx = (MpmCtx *)pectx;
    htp_tx_t *tx = (htp_tx_t *)txv;

    if (tx->response_headers == NULL)
        return;
    const HtpTxUserData *htud = (const HtpTxUserData *)htp_tx_get_user_data(tx);
    /* if the request wasn't flagged as having a trailer, we skip */
    if (htud && !htud->response_has_trailers)
        return;

    HtpState *htp_state = f->alstate;
    uint32_t buffer_len = 0;
    const uint8_t *buffer = DetectEngineHHDGetBufferForTX(tx, idx,
                                                    NULL, det_ctx,
                                                    f, htp_state,
                                                    flags,
                                                    &buffer_len);

    if (buffer_len >= mpm_ctx->minlen) {
        (void)mpm_table[mpm_ctx->mpm_type].Search(mpm_ctx,
                &det_ctx->mtcu, &det_ctx->pmq, buffer, buffer_len);
    }
}
#endif
int PrefilterTxHttpResponseHeaderNamesRegister(SigGroupHead *sgh, MpmCtx *mpm_ctx)
{
    SCEnter();

    int r = PrefilterAppendTxEngine(sgh, PrefilterTxHttpResponseHeaderNames,
        ALPROTO_HTTP, HTP_RESPONSE_HEADERS,
        mpm_ctx, NULL, KEYWORD_NAME " (response)");
    return r;
#if 0
    if (r != 0)
        return r;
    return PrefilterAppendTxEngine(sgh, PrefilterTxHttpResponseTrailers,
        ALPROTO_HTTP, HTP_RESPONSE_TRAILER,
        mpm_ctx, NULL, "http_header (response)");
#endif
}

int InspectEngineHttpHeaderNames(ThreadVars *tv,
        DetectEngineCtx *de_ctx, DetectEngineThreadCtx *det_ctx,
        const Signature *s, const SigMatchData *smd,
        Flow *f, uint8_t flags, void *alstate, void *tx, uint64_t tx_id)
{
    HtpState *htp_state = (HtpState *)alstate;
    uint32_t buffer_len = 0;
    uint8_t *buffer = GetBufferForTX(tx, tx_id,
            de_ctx, det_ctx, f, htp_state,
            flags, &buffer_len);
    if (buffer_len == 0)
        goto end;

    det_ctx->buffer_offset = 0;
    det_ctx->discontinue_matching = 0;
    det_ctx->inspection_recursion_counter = 0;
    int r = DetectEngineContentInspection(de_ctx, det_ctx, s, smd,
                                          f,
                                          buffer, buffer_len,
                                          0,
                                          DETECT_ENGINE_CONTENT_INSPECTION_MODE_STATE, NULL);
    if (r == 1)
        return DETECT_ENGINE_INSPECT_SIG_MATCH;

 end:
    if (flags & STREAM_TOSERVER) {
        if (AppLayerParserGetStateProgress(IPPROTO_TCP, ALPROTO_HTTP, tx, flags) > HTP_REQUEST_HEADERS)
            return DETECT_ENGINE_INSPECT_SIG_CANT_MATCH;
    } else {
        if (AppLayerParserGetStateProgress(IPPROTO_TCP, ALPROTO_HTTP, tx, flags) > HTP_RESPONSE_HEADERS)
            return DETECT_ENGINE_INSPECT_SIG_CANT_MATCH;
    }
    return DETECT_ENGINE_INSPECT_SIG_NO_MATCH;
}

/**
 * \brief The setup function for the http_header 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 DetectHttpHeaderNamesSetup(DetectEngineCtx *de_ctx, Signature *s, char *arg)
{
    s->init_data->list = g_buffer_id;
    return 0;
}

static void DetectHttpHeaderNamesSetupCallback(Signature *s)
{
    SCLogDebug("callback invoked by %u", s->id);
    s->mask |= SIG_MASK_REQUIRE_HTTP_STATE;
}

/**
 * \brief Registers the keyword handlers for the "http_header" keyword.
 */
void DetectHttpHeaderNamesRegister(void)
{
    sigmatch_table[DETECT_AL_HTTP_HEADER_NAMES].name = KEYWORD_NAME;
    sigmatch_table[DETECT_AL_HTTP_HEADER_NAMES].desc = BUFFER_NAME " sticky buffer";
    sigmatch_table[DETECT_AL_HTTP_HEADER_NAMES].url = DOC_URL DOC_VERSION "/rules/" KEYWORD_DOC;
    sigmatch_table[DETECT_AL_HTTP_HEADER_NAMES].Setup = DetectHttpHeaderNamesSetup;

    sigmatch_table[DETECT_AL_HTTP_HEADER_NAMES].flags |= SIGMATCH_NOOPT ;

    DetectAppLayerMpmRegister(BUFFER_NAME, SIG_FLAG_TOSERVER, 2,
            PrefilterTxHttpRequestHeaderNamesRegister);
    DetectAppLayerMpmRegister(BUFFER_NAME, SIG_FLAG_TOCLIENT, 2,
            PrefilterTxHttpResponseHeaderNamesRegister);

    DetectAppLayerInspectEngineRegister(BUFFER_NAME,
            ALPROTO_HTTP, SIG_FLAG_TOSERVER,
            InspectEngineHttpHeaderNames);
    DetectAppLayerInspectEngineRegister(BUFFER_NAME,
            ALPROTO_HTTP, SIG_FLAG_TOCLIENT,
            InspectEngineHttpHeaderNames);

    DetectBufferTypeSetDescriptionByName(BUFFER_NAME,
            BUFFER_DESC);

    DetectBufferTypeRegisterSetupCallback(BUFFER_NAME,
            DetectHttpHeaderNamesSetupCallback);

    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);
}