/* Copyright (C) 2007-2021 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 Gerardo Iglesias <iglesiasg@gmail.com>

 *

 * Implements icode keyword support

 */

#include "suricata-common.h"

#include "decode.h"

#include "detect.h"

#include "detect-parse.h"

#include "detect-engine-prefilter-common.h"

#include "detect-engine-uint.h"

#include "detect-engine-build.h"

#include "detect-icode.h"

#include "util-byte.h"

#include "util-unittest.h"

#include "util-unittest-helper.h"

#include "util-debug.h"

/**

 *\brief Regex for parsing our icode options

 */

static int DetectICodeMatch(DetectEngineThreadCtx *, Packet *,

        const Signature *, const SigMatchCtx *);

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

#ifdef UNITTESTS

static void DetectICodeRegisterTests(void);

#endif

void DetectICodeFree(DetectEngineCtx *, void *);

static int PrefilterSetupICode(DetectEngineCtx *de_ctx, SigGroupHead *sgh);

static bool PrefilterICodeIsPrefilterable(const Signature *s);

/**

 * \brief Registration function for icode: keyword

 */

void DetectICodeRegister (void)

{

    sigmatch_table[DETECT_ICODE].name = "icode";

    sigmatch_table[DETECT_ICODE].desc = "match on specific ICMP id-value";

    sigmatch_table[DETECT_ICODE].url = "/rules/header-keywords.html#icode";

    sigmatch_table[DETECT_ICODE].Match = DetectICodeMatch;

    sigmatch_table[DETECT_ICODE].Setup = DetectICodeSetup;

    sigmatch_table[DETECT_ICODE].Free = DetectICodeFree;

#ifdef UNITTESTS

    sigmatch_table[DETECT_ICODE].RegisterTests = DetectICodeRegisterTests;

#endif

    sigmatch_table[DETECT_ICODE].SupportsPrefilter = PrefilterICodeIsPrefilterable;

    sigmatch_table[DETECT_ICODE].SetupPrefilter = PrefilterSetupICode;

}

/**

 * \brief This function is used to match icode rule option set on a packet with those passed via

 * icode:

 *

 * \param t pointer to thread vars

 * \param det_ctx pointer to the pattern matcher thread

 * \param p pointer to the current packet

 * \param ctx pointer to the sigmatch that we will cast into DetectU8Data

 *

 * \retval 0 no match

 * \retval 1 match

 */

static int DetectICodeMatch (DetectEngineThreadCtx *det_ctx, Packet *p,

        const Signature *s, const SigMatchCtx *ctx)

{

    if (PKT_IS_PSEUDOPKT(p))

        return 0;

    uint8_t picode;

    if (PKT_IS_ICMPV4(p)) {

        picode = ICMPV4_GET_CODE(p);

    } else if (PKT_IS_ICMPV6(p)) {

        picode = ICMPV6_GET_CODE(p);

    } else {

        /* Packet not ICMPv4 nor ICMPv6 */

        return 0;

    }

    const DetectU8Data *icd = (const DetectU8Data *)ctx;

    return DetectU8Match(picode, icd);

}

/**

 * \brief this function is used to add the parsed icode data into the current signature

 *

 * \param de_ctx pointer to the Detection Engine Context

 * \param s pointer to the Current Signature

 * \param icodestr pointer to the user provided icode options

 *

 * \retval 0 on Success

 * \retval -1 on Failure

 */

static int DetectICodeSetup(DetectEngineCtx *de_ctx, Signature *s, const char *icodestr)

{

    DetectU8Data *icd = NULL;

    SigMatch *sm = NULL;

    icd = DetectU8Parse(icodestr);

    if (icd == NULL)

        return -1;

    sm = SigMatchAlloc();

    if (sm == NULL) goto error;

    sm->type = DETECT_ICODE;

    sm->ctx = (SigMatchCtx *)icd;

    SigMatchAppendSMToList(s, sm, DETECT_SM_LIST_MATCH);

    s->flags |= SIG_FLAG_REQUIRE_PACKET;

    return 0;

error:

    if (icd != NULL)

        rs_detect_u8_free(icd);

    if (sm != NULL) SCFree(sm);

    return -1;

}

/**

 * \brief this function will free memory associated with DetectU8Data

 *

 * \param ptr pointer to DetectU8Data

 */

void DetectICodeFree(DetectEngineCtx *de_ctx, void *ptr)

{

    rs_detect_u8_free(ptr);

}

/* prefilter code */

static void PrefilterPacketICodeMatch(DetectEngineThreadCtx *det_ctx,

        Packet *p, const void *pectx)

{

    if (PKT_IS_PSEUDOPKT(p)) {

        SCReturn;

    }

    uint8_t picode;

    if (PKT_IS_ICMPV4(p)) {

        picode = ICMPV4_GET_CODE(p);

    } else if (PKT_IS_ICMPV6(p)) {

        picode = ICMPV6_GET_CODE(p);

    } else {

        /* Packet not ICMPv4 nor ICMPv6 */

        return;

    }

    const PrefilterPacketU8HashCtx *h = pectx;

    const SigsArray *sa = h->array[picode];

    if (sa) {

        PrefilterAddSids(&det_ctx->pmq, sa->sigs, sa->cnt);

    }

}

static int PrefilterSetupICode(DetectEngineCtx *de_ctx, SigGroupHead *sgh)

{

    return PrefilterSetupPacketHeaderU8Hash(de_ctx, sgh, DETECT_ICODE, PrefilterPacketU8Set,

            PrefilterPacketU8Compare, PrefilterPacketICodeMatch);

}

static bool PrefilterICodeIsPrefilterable(const Signature *s)

{

    const SigMatch *sm;

    for (sm = s->init_data->smlists[DETECT_SM_LIST_MATCH] ; sm != NULL; sm = sm->next) {

        switch (sm->type) {

            case DETECT_ICODE:

                return true;

        }

    }

    return false;

}

#ifdef UNITTESTS

#include "detect-engine.h"

#include "detect-engine-mpm.h"

#include "detect-engine-alert.h"

/**

 * \test DetectICodeParseTest01 is a test for setting a valid icode value

 */

static int DetectICodeParseTest01(void)

{

    DetectU8Data *icd = DetectU8Parse("8");

    FAIL_IF_NULL(icd);

    FAIL_IF_NOT(icd->arg1 == 8);

    FAIL_IF_NOT(icd->mode == DETECT_UINT_EQ);

    DetectICodeFree(NULL, icd);

    PASS;

}

/**

 * \test DetectICodeParseTest02 is a test for setting a valid icode value

 *       with ">" operator

 */

static int DetectICodeParseTest02(void)

{

    DetectU8Data *icd = DetectU8Parse(">8");

    FAIL_IF_NULL(icd);

    FAIL_IF_NOT(icd->arg1 == 8);

    FAIL_IF_NOT(icd->mode == DETECT_UINT_GT);

    DetectICodeFree(NULL, icd);

    PASS;

}

/**

 * \test DetectICodeParseTest03 is a test for setting a valid icode value

 *       with "<" operator

 */

static int DetectICodeParseTest03(void)

{

    DetectU8Data *icd = DetectU8Parse("<8");

    FAIL_IF_NULL(icd);

    FAIL_IF_NOT(icd->arg1 == 8);

    FAIL_IF_NOT(icd->mode == DETECT_UINT_LT);

    DetectICodeFree(NULL, icd);

    PASS;

}

/**

 * \test DetectICodeParseTest04 is a test for setting a valid icode value

 *       with "<>" operator

 */

static int DetectICodeParseTest04(void)

{

    DetectU8Data *icd = DetectU8Parse("8<>20");

    FAIL_IF_NULL(icd);

    FAIL_IF_NOT(icd->arg1 == 8);

    FAIL_IF_NOT(icd->arg2 == 20);

    FAIL_IF_NOT(icd->mode == DETECT_UINT_RA);

    DetectICodeFree(NULL, icd);

    PASS;

}

/**

 * \test DetectICodeParseTest05 is a test for setting a valid icode value

 *       with spaces all around

 */

static int DetectICodeParseTest05(void)

{

    DetectU8Data *icd = DetectU8Parse("  8 ");

    FAIL_IF_NULL(icd);

    FAIL_IF_NOT(icd->arg1 == 8);

    FAIL_IF_NOT(icd->mode == DETECT_UINT_EQ);

    DetectICodeFree(NULL, icd);

    PASS;

}

/**

 * \test DetectICodeParseTest06 is a test for setting a valid icode value

 *       with ">" operator and spaces all around

 */

static int DetectICodeParseTest06(void)

{

    DetectU8Data *icd = DetectU8Parse("  >  8 ");

    FAIL_IF_NULL(icd);

    FAIL_IF_NOT(icd->arg1 == 8);

    FAIL_IF_NOT(icd->mode == DETECT_UINT_GT);

    DetectICodeFree(NULL, icd);

    PASS;

}

/**

 * \test DetectICodeParseTest07 is a test for setting a valid icode value

 *       with "<>" operator and spaces all around

 */

static int DetectICodeParseTest07(void)

{

    DetectU8Data *icd = DetectU8Parse("  8  <>  20 ");

    FAIL_IF_NULL(icd);

    FAIL_IF_NOT(icd->arg1 == 8);

    FAIL_IF_NOT(icd->arg2 == 20);

    FAIL_IF_NOT(icd->mode == DETECT_UINT_RA);

    DetectICodeFree(NULL, icd);

    PASS;

}

/**

 * \test DetectICodeParseTest08 is a test for setting an invalid icode value

 */

static int DetectICodeParseTest08(void)

{

    DetectU8Data *icd = DetectU8Parse("> 8 <> 20");

    FAIL_IF_NOT_NULL(icd);

    PASS;

}

/**

 * \test DetectICodeParseTest09 is a test for setting an invalid icode value

 *       with "<<" operator

 */

static int DetectICodeParseTest09(void)

{

    DetectU8Data *icd = DetectU8Parse("8<<20");

    FAIL_IF_NOT_NULL(icd);

    PASS;

}

/**

 * \test DetectICodeMatchTest01 is a test for checking the working of icode

 *       keyword by creating 5 rules and matching a crafted packet against

 *       them. 4 out of 5 rules shall trigger.

 */

static int DetectICodeMatchTest01(void)

{

    Packet *p = NULL;

    Signature *s = NULL;

    ThreadVars th_v;

    DetectEngineThreadCtx *det_ctx;

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

    p = UTHBuildPacket(NULL, 0, IPPROTO_ICMP);

    p->icmpv4h->code = 10;

    DetectEngineCtx *de_ctx = DetectEngineCtxInit();

    FAIL_IF_NULL(de_ctx);

    de_ctx->flags |= DE_QUIET;

    s = DetectEngineAppendSig(de_ctx, "alert icmp any any -> any any (icode:10; sid:1;)");

    FAIL_IF_NULL(s);

    s = DetectEngineAppendSig(de_ctx, "alert icmp any any -> any any (icode:<15; sid:2;)");

    FAIL_IF_NULL(s);

    s = DetectEngineAppendSig(de_ctx, "alert icmp any any -> any any (icode:>20; sid:3;)");

    FAIL_IF_NULL(s);

    s = DetectEngineAppendSig(de_ctx, "alert icmp any any -> any any (icode:8<>20; sid:4;)");

    FAIL_IF_NULL(s);

    s = DetectEngineAppendSig(de_ctx, "alert icmp any any -> any any (icode:20<>8; sid:5;)");

    FAIL_IF_NOT_NULL(s);

    SigGroupBuild(de_ctx);

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

    SigMatchSignatures(&th_v, de_ctx, det_ctx, p);

    FAIL_IF(PacketAlertCheck(p, 1) == 0);

    FAIL_IF(PacketAlertCheck(p, 2) == 0);

    FAIL_IF(PacketAlertCheck(p, 3));

    FAIL_IF(PacketAlertCheck(p, 4) == 0);

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

    DetectEngineCtxFree(de_ctx);

    UTHFreePackets(&p, 1);

    PASS;

}

/**

 * \brief this function registers unit tests for DetectICode

 */

void DetectICodeRegisterTests(void)

{

    UtRegisterTest("DetectICodeParseTest01", DetectICodeParseTest01);

    UtRegisterTest("DetectICodeParseTest02", DetectICodeParseTest02);

    UtRegisterTest("DetectICodeParseTest03", DetectICodeParseTest03);

    UtRegisterTest("DetectICodeParseTest04", DetectICodeParseTest04);

    UtRegisterTest("DetectICodeParseTest05", DetectICodeParseTest05);

    UtRegisterTest("DetectICodeParseTest06", DetectICodeParseTest06);

    UtRegisterTest("DetectICodeParseTest07", DetectICodeParseTest07);

    UtRegisterTest("DetectICodeParseTest08", DetectICodeParseTest08);

    UtRegisterTest("DetectICodeParseTest09", DetectICodeParseTest09);

    UtRegisterTest("DetectICodeMatchTest01", DetectICodeMatchTest01);

}

#endif /* UNITTESTS */