/* Copyright (C) 2007-2023 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>

 * \author Anoop Saldanha <anoopsaldanha@gmail.com>

 *

 * Implements the within keyword

 */

#include "suricata-common.h"

#include "decode.h"

#include "detect.h"

#include "detect-engine.h"

#include "detect-parse.h"

#include "detect-content.h"

#include "detect-uricontent.h"

#include "detect-byte.h"

#include "app-layer.h"

#include "flow-var.h"

#include "util-byte.h"

#include "util-debug.h"

#include "detect-pcre.h"

#include "detect-within.h"

#include "util-unittest.h"

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

#ifdef UNITTESTS

static void DetectWithinRegisterTests(void);

#endif

void DetectWithinRegister(void)

{

    sigmatch_table[DETECT_WITHIN].name = "within";

    sigmatch_table[DETECT_WITHIN].desc = "indicate that this content match has to be within a certain distance of the previous content keyword match";

    sigmatch_table[DETECT_WITHIN].url = "/rules/payload-keywords.html#within";

    sigmatch_table[DETECT_WITHIN].Match = NULL;

    sigmatch_table[DETECT_WITHIN].Setup = DetectWithinSetup;

#ifdef UNITTESTS

    sigmatch_table[DETECT_WITHIN].RegisterTests = DetectWithinRegisterTests;

#endif

}

/** \brief Setup within pattern (content/uricontent) modifier.

 *

 *  \todo apply to uricontent

 *

 *  \retval 0 ok

 *  \retval -1 error, sig needs to be invalidated

 */

static int DetectWithinSetup(DetectEngineCtx *de_ctx, Signature *s, const char *withinstr)

{

    const char *str = withinstr;

    /* retrieve the sm to apply the within against */

    SigMatch *pm = DetectGetLastSMFromLists(s, DETECT_CONTENT, -1);

    if (pm == NULL) {

        SCLogError("within needs preceding content option");

        return -1;

    }

    /* verify other conditions */

    DetectContentData *cd = (DetectContentData *)pm->ctx;

    if (cd->flags & DETECT_CONTENT_WITHIN) {

        SCLogError("can't use multiple withins for the same content.");

        return -1;

    }

    if ((cd->flags & DETECT_CONTENT_DEPTH) || (cd->flags & DETECT_CONTENT_OFFSET)) {

        SCLogError("can't use a relative "

                   "keyword like within/distance with a absolute "

                   "relative keyword like depth/offset for the same "

                   "content.");

        return -1;

    }

    if (cd->flags & DETECT_CONTENT_NEGATED && cd->flags & DETECT_CONTENT_FAST_PATTERN) {

        SCLogError("can't have a relative "

                   "negated keyword set along with a fast_pattern");

        return -1;

    }

    if (cd->flags & DETECT_CONTENT_FAST_PATTERN_ONLY) {

        SCLogError("can't have a relative "

                   "keyword set along with a fast_pattern:only;");

        return -1;

    }

    if (str[0] != '-' && isalpha((unsigned char)str[0])) {

        DetectByteIndexType index;

        if (!DetectByteRetrieveSMVar(str, s, &index)) {

            SCLogError("unknown byte_ keyword var "

                       "seen in within - %s",

                    str);

            return -1;

        }

        cd->within = index;

        cd->flags |= DETECT_CONTENT_WITHIN_VAR;

    } else {

        if ((StringParseI32RangeCheck(&cd->within, 0, 0, str, -DETECT_CONTENT_VALUE_MAX,

                     DETECT_CONTENT_VALUE_MAX) < 0)) {

            SCLogError("invalid value for within: %s", str);

            return -1;

        }

        if (cd->within < (int32_t)cd->content_len) {

            SCLogError("within argument \"%" PRIi32 "\" is "

                       "less than the content length \"%" PRIu32 "\" which is invalid, since "

                       "this will never match.  Invalidating signature",

                    cd->within, cd->content_len);

            return -1;

        }

    }

    cd->flags |= DETECT_CONTENT_WITHIN;

    /* these are the only ones against which we set a flag.  We have other

     * relative keywords like byttest, isdataat, bytejump, but we don't

     * set a flag against them */

    SigMatch *prev_pm = DetectGetLastSMByListPtr(s, pm->prev,

            DETECT_CONTENT, DETECT_PCRE, -1);

    if (prev_pm == NULL) {

        return 0;

    }

    if (prev_pm->type == DETECT_CONTENT) {

        DetectContentData *prev_cd = (DetectContentData *)prev_pm->ctx;

        if (prev_cd->flags & DETECT_CONTENT_FAST_PATTERN_ONLY) {

            SCLogError("previous keyword "

                       "has a fast_pattern:only; set. Can't "

                       "have relative keywords around a fast_pattern "

                       "only content");

            return -1;

        }

        prev_cd->flags |= DETECT_CONTENT_WITHIN_NEXT;

    } else if (prev_pm->type == DETECT_PCRE) {

        DetectPcreData *pd = (DetectPcreData *)prev_pm->ctx;

        pd->flags |= DETECT_PCRE_RELATIVE_NEXT;

    }

    return 0;

}

/***********************************Unittests**********************************/

#ifdef UNITTESTS

#include "util-unittest-helper.h"

 /**

 * \test DetectWithinTestPacket01 is a test to check matches of

 * within, if the previous keyword is pcre (bug 145)

 */

static int DetectWithinTestPacket01 (void)

{

    uint8_t *buf = (uint8_t *)"GET /AllWorkAndNoPlayMakesWillADullBoy HTTP/1.0"

                    "User-Agent: Wget/1.11.4"

                    "Accept: */*"

                    "Host: www.google.com"

                    "Connection: Keep-Alive"

                    "Date: Mon, 04 Jan 2010 17:29:39 GMT";

    uint16_t buflen = strlen((char *)buf);

    Packet *p = UTHBuildPacket((uint8_t *)buf, buflen, IPPROTO_TCP);

    FAIL_IF_NULL(p);

    char sig[] = "alert tcp any any -> any any (msg:\"pcre with within "

                 "modifier\"; pcre:\"/AllWorkAndNoPlayMakesWillADullBoy/\";"

                 " content:\"HTTP\"; within:5; sid:49; rev:1;)";

    int result = UTHPacketMatchSig(p, sig);

    FAIL_IF_NOT(result == 1);

    UTHFreePacket(p);

    PASS;

}

static int DetectWithinTestPacket02 (void)

{

    uint8_t *buf = (uint8_t *)"Zero Five Ten Fourteen";

    uint16_t buflen = strlen((char *)buf);

    Packet *p = UTHBuildPacket((uint8_t *)buf, buflen, IPPROTO_TCP);

    FAIL_IF_NULL(p);

    char sig[] = "alert tcp any any -> any any (msg:\"pcre with within "

                 "modifier\"; content:\"Five\"; content:\"Ten\"; within:3; distance:1; sid:1;)";

    int result = UTHPacketMatchSig(p, sig);

    FAIL_IF_NOT(result == 1);

    UTHFreePacket(p);

    PASS;

}

static int DetectWithinTestVarSetup(void)

{

    char sig[] = "alert tcp any any -> any any ( "

        "msg:\"test rule\"; "

        "content:\"abc\"; "

        "http_client_body; "

        "byte_extract:2,0,somevar,relative; "

        "content:\"def\"; "

        "within:somevar; "

        "http_client_body; "

        "sid:4; rev:1;)";

    DetectEngineCtx *de_ctx = DetectEngineCtxInit();

    FAIL_IF_NULL(de_ctx);

    Signature *s = DetectEngineAppendSig(de_ctx, sig);

    FAIL_IF_NULL(s);

    DetectEngineCtxFree(de_ctx);

    PASS;

}

void DetectWithinRegisterTests(void)

{

    UtRegisterTest("DetectWithinTestPacket01", DetectWithinTestPacket01);

    UtRegisterTest("DetectWithinTestPacket02", DetectWithinTestPacket02);

    UtRegisterTest("DetectWithinTestVarSetup", DetectWithinTestVarSetup);

}

#endif /* UNITTESTS */