/* Copyright (C) 2007-2010 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 Brian Rectanus <brectanu@gmail.com>

 *

 * Implements the seq keyword.

 */

#include "suricata-common.h"

#include "decode.h"

#include "detect.h"

#include "detect-parse.h"

#include "detect-engine.h"

#include "detect-engine-prefilter.h"

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

#include "detect-engine-build.h"

#include "detect-engine-uint.h"

#include "detect-tcp-seq.h"

#include "util-byte.h"

#include "util-unittest.h"

#include "util-unittest-helper.h"

#include "util-debug.h"

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

static int DetectSeqMatch(DetectEngineThreadCtx *,

                          Packet *, const Signature *, const SigMatchCtx *);

#ifdef UNITTESTS

static void DetectSeqRegisterTests(void);

#endif

static void DetectSeqFree(DetectEngineCtx *, void *);

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

static bool PrefilterTcpSeqIsPrefilterable(const Signature *s);

void DetectSeqRegister(void)

{

    sigmatch_table[DETECT_SEQ].name = "tcp.seq";

    sigmatch_table[DETECT_SEQ].alias = "seq";

    sigmatch_table[DETECT_SEQ].desc = "check for a specific TCP sequence number";

    sigmatch_table[DETECT_SEQ].url = "/rules/header-keywords.html#seq";

    sigmatch_table[DETECT_SEQ].Match = DetectSeqMatch;

    sigmatch_table[DETECT_SEQ].Setup = DetectSeqSetup;

    sigmatch_table[DETECT_SEQ].Free = DetectSeqFree;

    sigmatch_table[DETECT_SEQ].flags = SIGMATCH_INFO_UINT32;

#ifdef UNITTESTS

    sigmatch_table[DETECT_SEQ].RegisterTests = DetectSeqRegisterTests;

#endif

    sigmatch_table[DETECT_SEQ].SupportsPrefilter = PrefilterTcpSeqIsPrefilterable;

    sigmatch_table[DETECT_SEQ].SetupPrefilter = PrefilterSetupTcpSeq;

}

/**

 * \internal

 * \brief This function is used to match packets with a given Seq number

 *

 * \param t pointer to thread vars

 * \param det_ctx pointer to the pattern matcher thread

 * \param p pointer to the current packet

 * \param m pointer to the sigmatch that we will cast into DetectSeqData

 *

 * \retval 0 no match

 * \retval 1 match

 */

static int DetectSeqMatch(DetectEngineThreadCtx *det_ctx,

                          Packet *p, const Signature *s, const SigMatchCtx *ctx)

{

    const DetectU32Data *data = (const DetectU32Data *)ctx;

    DEBUG_VALIDATE_BUG_ON(PKT_IS_PSEUDOPKT(p));

    /* This is only needed on TCP packets */

    if (!(PacketIsTCP(p))) {

        return 0;

    }

    return DetectU32Match(TCP_GET_RAW_SEQ(PacketGetTCP(p)), data);

}

/**

 * \internal

 * \brief this function is used to add the seq option into the signature

 *

 * \param de_ctx pointer to the Detection Engine Context

 * \param s pointer to the Current Signature

 * \param optstr pointer to the user provided options

 *

 * \retval 0 on Success

 * \retval -1 on Failure

 */

static int DetectSeqSetup (DetectEngineCtx *de_ctx, Signature *s, const char *optstr)

{

    DetectU32Data *data = SCDetectU32Parse(optstr);

    if (data == NULL)

        return -1;

    if (SCSigMatchAppendSMToList(

                de_ctx, s, DETECT_SEQ, (SigMatchCtx *)data, DETECT_SM_LIST_MATCH) == NULL) {

        DetectSeqFree(de_ctx, data);

        return -1;

    }

    s->flags |= SIG_FLAG_REQUIRE_PACKET;

    return 0;

}

/**

 * \internal

 * \brief this function will free memory associated with seq option

 *

 * \param data pointer to seq configuration data

 */

static void DetectSeqFree(DetectEngineCtx *de_ctx, void *ptr)

{

    SCDetectU32Free(ptr);

}

/* prefilter code */

static void

PrefilterPacketSeqMatch(DetectEngineThreadCtx *det_ctx, Packet *p, const void *pectx)

{

    const PrefilterPacketHeaderCtx *ctx = pectx;

    DEBUG_VALIDATE_BUG_ON(PKT_IS_PSEUDOPKT(p));

    if (!PrefilterPacketHeaderExtraMatch(ctx, p))

        return;

    if (p->proto == IPPROTO_TCP && PacketIsTCP(p)) {

        DetectU32Data du32;

        du32.mode = ctx->v1.u8[0];

        du32.arg1 = ctx->v1.u32[1];

        du32.arg2 = ctx->v1.u32[2];

        if (DetectU32Match(TCP_GET_RAW_SEQ(PacketGetTCP(p)), &du32)) {

            SCLogDebug("packet matches TCP seq %u", ctx->v1.u32[0]);

            PrefilterAddSids(&det_ctx->pmq, ctx->sigs_array, ctx->sigs_cnt);

        }

    }

}

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

{

    return PrefilterSetupPacketHeader(de_ctx, sgh, DETECT_SEQ, SIG_MASK_REQUIRE_REAL_PKT,

            PrefilterPacketU32Set, PrefilterPacketU32Compare, PrefilterPacketSeqMatch);

}

static bool PrefilterTcpSeqIsPrefilterable(const Signature *s)

{

    return PrefilterIsPrefilterableById(s, DETECT_SEQ);

}

#ifdef UNITTESTS

/**

 * \test DetectSeqSigTest01 tests parses

 */

static int DetectSeqSigTest01(void)

{

    int result = 0;

    DetectEngineCtx *de_ctx = DetectEngineCtxInit();

    if (de_ctx == NULL)

        goto end;

    /* These three are crammed in here as there is no Parse */

    if (SigInit(de_ctx,

                "alert tcp any any -> any any "

                "(msg:\"Testing seq\";seq:foo;sid:1;)") != NULL)

    {

        printf("invalid seq accepted: ");

        goto cleanup;

    }

    if (SigInit(de_ctx,

                "alert tcp any any -> any any "

                "(msg:\"Testing seq\";seq:9999999999;sid:1;)") != NULL)

    {

        printf("overflowing seq accepted: ");

        goto cleanup;

    }

    if (SigInit(de_ctx,

                "alert tcp any any -> any any "

                "(msg:\"Testing seq\";seq:-100;sid:1;)") != NULL)

    {

        printf("negative seq accepted: ");

        goto cleanup;

    }

    result = 1;

cleanup:

    if (de_ctx) {

        SigGroupCleanup(de_ctx);

        SigCleanSignatures(de_ctx);

        DetectEngineCtxFree(de_ctx);

    }

end:

    return result;

}

/**

 * \test DetectSeqSigTest02 tests seq keyword

 */

static int DetectSeqSigTest02(void)

{

    int result = 0;

    uint8_t *buf = (uint8_t *)"Hi all!";

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

    Packet *p[3];

    p[0] = UTHBuildPacket((uint8_t *)buf, buflen, IPPROTO_TCP);

    p[1] = UTHBuildPacket((uint8_t *)buf, buflen, IPPROTO_TCP);

    p[2] = UTHBuildPacket((uint8_t *)buf, buflen, IPPROTO_ICMP);

    if (p[0] == NULL || p[1] == NULL ||p[2] == NULL)

        goto end;

    /* TCP w/seq=42 */

    p[0]->l4.hdrs.tcph->th_seq = htonl(42);

    /* TCP w/seq=100 */

    p[1]->l4.hdrs.tcph->th_seq = htonl(100);

    const char *sigs[2];

    sigs[0]= "alert tcp any any -> any any (msg:\"Testing seq\"; seq:41; sid:1;)";

    sigs[1]= "alert tcp any any -> any any (msg:\"Testing seq\"; seq:42; sid:2;)";

    uint32_t sid[2] = {1, 2};

    uint32_t results[3][2] = {

                              /* packet 0 match sid 1 but should not match sid 2 */

                              {0, 1},

                              /* packet 1 should not match */

                              {0, 0},

                              /* packet 2 should not match */

                              {0, 0} };

    result = UTHGenericTest(p, 3, sigs, sid, (uint32_t *) results, 2);

    UTHFreePackets(p, 3);

end:

    return result;

}

/**

 * \internal

 * \brief This function registers unit tests for DetectSeq

 */

static void DetectSeqRegisterTests(void)

{

    UtRegisterTest("DetectSeqSigTest01", DetectSeqSigTest01);

    UtRegisterTest("DetectSeqSigTest02", DetectSeqSigTest02);

}

#endif /* UNITTESTS */