/* Copyright (C) 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 Jeff Lucovsky <jeff@lucovsky.org>

 *

 */

#include "suricata-common.h"

#include "detect.h"

#include "detect-engine.h"

#include "detect-engine-buffer.h"

#include "detect-engine-mpm.h"

#include "detect-icmpv4hdr.h"

#include "detect-engine-prefilter.h"

/* prototypes */

static int DetectIcmpv4HdrSetup(DetectEngineCtx *, Signature *, const char *);

#ifdef UNITTESTS

void DetectIcmpv4HdrRegisterTests(void);

#endif

static int g_icmpv4hdr_buffer_id = 0;

static InspectionBuffer *GetData(DetectEngineThreadCtx *det_ctx,

        const DetectEngineTransforms *transforms, Packet *p, const int list_id);

/**

 * \brief Registration function for icmpv4.hdr: keyword

 */

void DetectIcmpv4HdrRegister(void)

{

    sigmatch_table[DETECT_ICMPV4HDR].name = "icmpv4.hdr";

    sigmatch_table[DETECT_ICMPV4HDR].desc = "sticky buffer to match on the ICMP v4 header";

    sigmatch_table[DETECT_ICMPV4HDR].url = "/rules/header-keywords.html#icmpv4-hdr";

    sigmatch_table[DETECT_ICMPV4HDR].Setup = DetectIcmpv4HdrSetup;

    sigmatch_table[DETECT_ICMPV4HDR].flags |= SIGMATCH_NOOPT | SIGMATCH_INFO_STICKY_BUFFER;

#ifdef UNITTESTS

    sigmatch_table[DETECT_ICMPV4HDR].RegisterTests = DetectIcmpv4HdrRegisterTests;

#endif

    g_icmpv4hdr_buffer_id = DetectBufferTypeRegister("icmpv4.hdr");

    BUG_ON(g_icmpv4hdr_buffer_id < 0);

    DetectBufferTypeSupportsPacket("icmpv4.hdr");

    DetectPktMpmRegister("icmpv4.hdr", 2, PrefilterGenericMpmPktRegister, GetData);

    DetectPktInspectEngineRegister("icmpv4.hdr", GetData, DetectEngineInspectPktBufferGeneric);

}

/**

 * \brief setup icmpv4.hdr sticky buffer

 *

 * \param de_ctx pointer to the Detection Engine Context

 * \param s pointer to the Current Signature

 * \param _unused unused

 *

 * \retval 0 on Success

 * \retval -1 on Failure

 */

static int DetectIcmpv4HdrSetup(DetectEngineCtx *de_ctx, Signature *s, const char *_unused)

{

    if (!(DetectProtoContainsProto(&s->proto, IPPROTO_ICMP)))

        return -1;

    s->proto.flags |= DETECT_PROTO_IPV4;

    s->flags |= SIG_FLAG_REQUIRE_PACKET;

    if (SCDetectBufferSetActiveList(de_ctx, s, g_icmpv4hdr_buffer_id) < 0)

        return -1;

    return 0;

}

static InspectionBuffer *GetData(DetectEngineThreadCtx *det_ctx,

        const DetectEngineTransforms *transforms, Packet *p, const int list_id)

{

    SCEnter();

    if (!PacketIsICMPv4(p)) {

        SCReturnPtr(NULL, "InspectionBuffer");

    }

    InspectionBuffer *buffer = InspectionBufferGet(det_ctx, list_id);

    if (buffer->inspect == NULL) {

        const ICMPV4Hdr *icmpv4h = PacketGetICMPv4(p);

        uint16_t hlen = ICMPV4_GET_HLEN_ICMPV4H(p);

        if (((uint8_t *)icmpv4h + (ptrdiff_t)hlen) >

                ((uint8_t *)GET_PKT_DATA(p) + (ptrdiff_t)GET_PKT_LEN(p))) {

            SCLogDebug("data out of range: %p > %p", ((uint8_t *)icmpv4h + (ptrdiff_t)hlen),

                    ((uint8_t *)GET_PKT_DATA(p) + (ptrdiff_t)GET_PKT_LEN(p)));

            SCReturnPtr(NULL, "InspectionBuffer");

        }

        const uint32_t data_len = hlen;

        const uint8_t *data = (const uint8_t *)icmpv4h;

        InspectionBufferSetupAndApplyTransforms(

                det_ctx, list_id, buffer, data, data_len, transforms);

    }

    SCReturnPtr(buffer, "InspectionBuffer");

}

#ifdef UNITTESTS

#include "tests/detect-icmpv4hdr.c"

#endif