/* Copyright (C) 2007-2020 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.

 */

/**

 * \file

 *

 * \author Victor Julien <victor@inliniac.net>

 *

 * Implements the nocase keyword

 */

#include "suricata-common.h"

#include "detect.h"

#include "detect-engine.h"

#include "detect-engine-prefilter.h"

#include "detect-engine-build.h"

#include "detect-parse.h"

#include "detect-transform-strip-whitespace.h"

#include "util-unittest.h"

#include "util-print.h"

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

#ifdef UNITTESTS

static void DetectTransformStripWhitespaceRegisterTests(void);

#endif

static void TransformStripWhitespace(InspectionBuffer *buffer, void *options);

static bool TransformStripWhitespaceValidate(const uint8_t *content, uint16_t content_len, void *options);

void DetectTransformStripWhitespaceRegister(void)

{

    sigmatch_table[DETECT_TRANSFORM_STRIP_WHITESPACE].name = "strip_whitespace";

    sigmatch_table[DETECT_TRANSFORM_STRIP_WHITESPACE].desc =

        "modify buffer to strip whitespace before inspection";

    sigmatch_table[DETECT_TRANSFORM_STRIP_WHITESPACE].url =

        "/rules/transforms.html#strip-whitespace";

    sigmatch_table[DETECT_TRANSFORM_STRIP_WHITESPACE].Transform =

        TransformStripWhitespace;

    sigmatch_table[DETECT_TRANSFORM_STRIP_WHITESPACE].TransformValidate =

        TransformStripWhitespaceValidate;

    sigmatch_table[DETECT_TRANSFORM_STRIP_WHITESPACE].Setup =

        DetectTransformStripWhitespaceSetup;

#ifdef UNITTESTS

    sigmatch_table[DETECT_TRANSFORM_STRIP_WHITESPACE].RegisterTests =

        DetectTransformStripWhitespaceRegisterTests;

#endif

    sigmatch_table[DETECT_TRANSFORM_STRIP_WHITESPACE].flags |= SIGMATCH_NOOPT;

}

/**

 *  \internal

 *  \brief Apply the nocase keyword to the last pattern match, either content or uricontent

 *  \param det_ctx detection engine ctx

 *  \param s signature

 *  \param nullstr should be null

 *  \retval 0 ok

 *  \retval -1 failure

 */

static int DetectTransformStripWhitespaceSetup (DetectEngineCtx *de_ctx, Signature *s, const char *nullstr)

{

    SCEnter();

    int r = DetectSignatureAddTransform(s, DETECT_TRANSFORM_STRIP_WHITESPACE, NULL);

    SCReturnInt(r);

}

/*

 *  \brief Validate content bytes to see if it's compatible with this transform

 *  \param content Byte array to check for compatibility

 *  \param content_len Number of bytes to check

 *  \param options Ignored

 *  \retval false If the string contains spaces

 *  \retval true Otherwise.

 */

static bool TransformStripWhitespaceValidate(const uint8_t *content,

        uint16_t content_len, void *options)

{

    if (content) {

        for (uint32_t i = 0; i < content_len; i++) {

            if (isspace(*content++)) {

                return false;

            }

        }

    }

    return true;

}

static void TransformStripWhitespace(InspectionBuffer *buffer, void *options)

{

    const uint8_t *input = buffer->inspect;

    const uint32_t input_len = buffer->inspect_len;

    if (input_len == 0) {

        return;

    }

    // we can only shrink

    uint8_t *output = InspectionBufferCheckAndExpand(buffer, input_len);

    if (output == NULL) {

        return;

    }

    uint8_t *oi = output, *os = output;

    //PrintRawDataFp(stdout, input, input_len);

    for (uint32_t i = 0; i < input_len; i++) {

        if (!isspace(*input)) {

            *oi++ = *input;

        }

        input++;

    }

    uint32_t output_size = oi - os;

    //PrintRawDataFp(stdout, output, output_size);

    InspectionBufferTruncate(buffer, output_size);

}

#ifdef UNITTESTS

static int TransformDoubleWhitespace(InspectionBuffer *buffer)

{

    const uint8_t *input = buffer->inspect;

    const uint32_t input_len = buffer->inspect_len;

    uint8_t output[input_len * 2]; // if all chars are whitespace this fits

    memset(&output, 0, input_len * 2);

    uint8_t *oi = output, *os = output;

    PrintRawDataFp(stdout, input, input_len);

    for (uint32_t i = 0; i < input_len; i++) {

        if (isspace(*input)) {

            *oi++ = *input;

        }

        *oi++ = *input;

        input++;

    }

    uint32_t output_size = oi - os;

    PrintRawDataFp(stdout, output, output_size);

    InspectionBufferCopy(buffer, os, output_size);

    return 0;

}

static int DetectTransformStripWhitespaceTest01(void)

{

    const uint8_t *input = (const uint8_t *)" A B C D ";

    uint32_t input_len = strlen((char *)input);

    InspectionBuffer buffer;

    InspectionBufferInit(&buffer, 8);

    InspectionBufferSetup(NULL, -1, &buffer, input, input_len);

    PrintRawDataFp(stdout, buffer.inspect, buffer.inspect_len);

    TransformStripWhitespace(&buffer, NULL);

    PrintRawDataFp(stdout, buffer.inspect, buffer.inspect_len);

    InspectionBufferFree(&buffer);

    PASS;

}

static int DetectTransformStripWhitespaceTest02(void)

{

    const uint8_t *input = (const uint8_t *)" A B C D ";

    uint32_t input_len = strlen((char *)input);

    InspectionBuffer buffer;

    InspectionBufferInit(&buffer, 8);

    InspectionBufferSetup(NULL, -1, &buffer, input, input_len);

    PrintRawDataFp(stdout, buffer.inspect, buffer.inspect_len);

    TransformDoubleWhitespace(&buffer);

    PrintRawDataFp(stdout, buffer.inspect, buffer.inspect_len);

    TransformDoubleWhitespace(&buffer);

    PrintRawDataFp(stdout, buffer.inspect, buffer.inspect_len);

    TransformStripWhitespace(&buffer, NULL);

    PrintRawDataFp(stdout, buffer.inspect, buffer.inspect_len);

    InspectionBufferFree(&buffer);

    PASS;

}

static int DetectTransformStripWhitespaceTest03(void)

{

    const char rule[] = "alert http any any -> any any (http_request_line; strip_whitespace; content:\"GET/HTTP\"; sid:1;)";

    ThreadVars th_v;

    DetectEngineThreadCtx *det_ctx = NULL;

    memset(&th_v, 0, sizeof(th_v));

    DetectEngineCtx *de_ctx = DetectEngineCtxInit();

    FAIL_IF_NULL(de_ctx);

    Signature *s = DetectEngineAppendSig(de_ctx, rule);

    FAIL_IF_NULL(s);

    SigGroupBuild(de_ctx);

    DetectEngineThreadCtxInit(&th_v, (void *)de_ctx, (void *)&det_ctx);

    DetectEngineThreadCtxDeinit(&th_v, (void *)det_ctx);

    DetectEngineCtxFree(de_ctx);

    PASS;

}

static void DetectTransformStripWhitespaceRegisterTests(void)

{

    UtRegisterTest("DetectTransformStripWhitespaceTest01",

            DetectTransformStripWhitespaceTest01);

    UtRegisterTest("DetectTransformStripWhitespaceTest02",

            DetectTransformStripWhitespaceTest02);

    UtRegisterTest("DetectTransformStripWhitespaceTest03",

            DetectTransformStripWhitespaceTest03);

}

#endif