/* Copyright (C) 2007-2013 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 Galvan <iglesiasg@gmail.com>
 *
 * Implements the icmp_id keyword
 */

#include "suricata-common.h"
#include "debug.h"
#include "decode.h"

#include "detect.h"
#include "detect-parse.h"

#include "detect-icmp-id.h"

#include "util-byte.h"
#include "util-unittest.h"
#include "util-unittest-helper.h"
#include "util-debug.h"

#define PARSE_REGEX "^\\s*(\"\\s*)?([0-9]+)(\\s*\")?\\s*$"

static pcre *parse_regex;
static pcre_extra *parse_regex_study;

int DetectIcmpIdMatch(ThreadVars *, DetectEngineThreadCtx *, Packet *, Signature *, const SigMatchCtx *);
static int DetectIcmpIdSetup(DetectEngineCtx *, Signature *, char *);
void DetectIcmpIdRegisterTests(void);
void DetectIcmpIdFree(void *);

/**
 * \brief Registration function for icode: icmp_id
 */
void DetectIcmpIdRegister (void)
{
    sigmatch_table[DETECT_ICMP_ID].name = "icmp_id";
    sigmatch_table[DETECT_ICMP_ID].desc = "check for a ICMP id";
    sigmatch_table[DETECT_ICMP_ID].url = "https://redmine.openinfosecfoundation.org/projects/suricata/wiki/Header_keywords#icmp_id";
    sigmatch_table[DETECT_ICMP_ID].Match = DetectIcmpIdMatch;
    sigmatch_table[DETECT_ICMP_ID].Setup = DetectIcmpIdSetup;
    sigmatch_table[DETECT_ICMP_ID].Free = DetectIcmpIdFree;
    sigmatch_table[DETECT_ICMP_ID].RegisterTests = DetectIcmpIdRegisterTests;

    const char *eb;
    int eo;
    int opts = 0;

    parse_regex = pcre_compile(PARSE_REGEX, opts, &eb, &eo, NULL);
    if (parse_regex == NULL) {
        SCLogError(SC_ERR_PCRE_COMPILE, "pcre compile of \"%s\" failed at offset %" PRId32 ": %s", PARSE_REGEX, eo, eb);
        goto error;
    }

    parse_regex_study = pcre_study(parse_regex, 0, &eb);
    if (eb != NULL) {
        SCLogError(SC_ERR_PCRE_STUDY, "pcre study failed: %s", eb);
        goto error;
    }
    return;

error:
    return;
}

/**
 * \brief This function is used to match icmp_id rule option set on a packet
 *
 * \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 DetectIcmpIdData
 *
 * \retval 0 no match
 * \retval 1 match
 */
int DetectIcmpIdMatch (ThreadVars *t, DetectEngineThreadCtx *det_ctx, Packet *p, Signature *s, const SigMatchCtx *ctx)
{
    uint16_t pid;
    const DetectIcmpIdData *iid = (const DetectIcmpIdData *)ctx;

    if (PKT_IS_PSEUDOPKT(p))
        return 0;

    if (PKT_IS_ICMPV4(p)) {
        switch (ICMPV4_GET_TYPE(p)){
            case ICMP_ECHOREPLY:
            case ICMP_ECHO:
            case ICMP_TIMESTAMP:
            case ICMP_TIMESTAMPREPLY:
            case ICMP_INFO_REQUEST:
            case ICMP_INFO_REPLY:
            case ICMP_ADDRESS:
            case ICMP_ADDRESSREPLY:
                SCLogDebug("ICMPV4_GET_ID(p) %"PRIu16" (network byte order), "
                        "%"PRIu16" (host byte order)", ICMPV4_GET_ID(p),
                        ntohs(ICMPV4_GET_ID(p)));

                pid = ICMPV4_GET_ID(p);
                break;
            default:
                SCLogDebug("Packet has no id field");
                return 0;
        }
    } else if (PKT_IS_ICMPV6(p)) {
        switch (ICMPV6_GET_TYPE(p)) {
            case ICMP6_ECHO_REQUEST:
            case ICMP6_ECHO_REPLY:
                SCLogDebug("ICMPV6_GET_ID(p) %"PRIu16" (network byte order), "
                        "%"PRIu16" (host byte order)", ICMPV6_GET_ID(p),
                        ntohs(ICMPV6_GET_ID(p)));

                pid = ICMPV6_GET_ID(p);
                break;
            default:
                SCLogDebug("Packet has no id field");
                return 0;
        }
    } else {
        SCLogDebug("Packet not ICMPV4 nor ICMPV6");
        return 0;
    }

    if (pid == iid->id)
        return 1;

    return 0;
}

/**
 * \brief This function is used to parse icmp_id option passed via icmp_id: keyword
 *
 * \param icmpidstr Pointer to the user provided icmp_id options
 *
 * \retval iid pointer to DetectIcmpIdData on success
 * \retval NULL on failure
 */
DetectIcmpIdData *DetectIcmpIdParse (char *icmpidstr)
{
    DetectIcmpIdData *iid = NULL;
    char *substr[3] = {NULL, NULL, NULL};
#define MAX_SUBSTRINGS 30
    int ret = 0, res = 0;
    int ov[MAX_SUBSTRINGS];

    ret = pcre_exec(parse_regex, parse_regex_study, icmpidstr, strlen(icmpidstr), 0, 0, ov, MAX_SUBSTRINGS);
    if (ret < 1 || ret > 4) {
        SCLogError(SC_ERR_PCRE_MATCH, "Parse error %s", icmpidstr);
        goto error;
    }

    int i;
    const char *str_ptr;
    for (i = 1; i < ret; i++) {
        res = pcre_get_substring((char *)icmpidstr, ov, MAX_SUBSTRINGS, i, &str_ptr);
        if (res < 0) {
            SCLogError(SC_ERR_PCRE_GET_SUBSTRING, "pcre_get_substring failed");
            goto error;
        }
        substr[i-1] = (char *)str_ptr;
    }

    iid = SCMalloc(sizeof(DetectIcmpIdData));
    if (unlikely(iid == NULL))
        goto error;
    iid->id = 0;

    if (substr[0]!= NULL && strlen(substr[0]) != 0) {
        if (substr[2] == NULL) {
            SCLogError(SC_ERR_INVALID_ARGUMENT, "Missing close quote in input");
            goto error;
        }
    } else {
        if (substr[2] != NULL) {
            SCLogError(SC_ERR_INVALID_ARGUMENT, "Missing open quote in input");
            goto error;
        }
    }

    /** \todo can ByteExtractStringUint16 do this? */
    uint16_t id = 0;
    if (ByteExtractStringUint16(&id, 10, 0, substr[1]) < 0) {
        SCLogError(SC_ERR_INVALID_ARGUMENT, "specified icmp id %s is not "
                                        "valid", substr[1]);
        goto error;
    }
    iid->id = htons(id);

    for (i = 0; i < 3; i++) {
        if (substr[i] != NULL) SCFree(substr[i]);
    }
    return iid;

error:
    for (i = 0; i < 3; i++) {
        if (substr[i] != NULL) SCFree(substr[i]);
    }
    if (iid != NULL) DetectIcmpIdFree(iid);
    return NULL;

}

/**
 * \brief this function is used to add the parsed icmp_id data into the current signature
 *
 * \param de_ctx pointer to the Detection Engine Context
 * \param s pointer to the Current Signature
 * \param icmpidstr pointer to the user provided icmp_id option
 *
 * \retval 0 on Success
 * \retval -1 on Failure
 */
static int DetectIcmpIdSetup (DetectEngineCtx *de_ctx, Signature *s, char *icmpidstr)
{
    DetectIcmpIdData *iid = NULL;
    SigMatch *sm = NULL;

    iid = DetectIcmpIdParse(icmpidstr);
    if (iid == NULL) goto error;

    sm = SigMatchAlloc();
    if (sm == NULL) goto error;

    sm->type = DETECT_ICMP_ID;
    sm->ctx = (SigMatchCtx *)iid;

    SigMatchAppendSMToList(s, sm, DETECT_SM_LIST_MATCH);
    s->flags |= SIG_FLAG_REQUIRE_PACKET;

    return 0;

error:
    if (iid != NULL) DetectIcmpIdFree(iid);
    if (sm != NULL) SCFree(sm);
    return -1;

}

/**
 * \brief this function will free memory associated with DetectIcmpIdData
 *
 * \param ptr pointer to DetectIcmpIdData
 */
void DetectIcmpIdFree (void *ptr)
{
    DetectIcmpIdData *iid = (DetectIcmpIdData *)ptr;
    SCFree(iid);
}

#ifdef UNITTESTS

#include "detect-parse.h"
#include "detect-engine.h"
#include "detect-engine-mpm.h"

/**
 * \test DetectIcmpIdParseTest01 is a test for setting a valid icmp_id value
 */
int DetectIcmpIdParseTest01 (void)
{
    DetectIcmpIdData *iid = NULL;
    iid = DetectIcmpIdParse("300");
    if (iid != NULL && iid->id == htons(300)) {
        DetectIcmpIdFree(iid);
        return 1;
    }
    return 0;
}

/**
 * \test DetectIcmpIdParseTest02 is a test for setting a valid icmp_id value
 *       with spaces all around
 */
int DetectIcmpIdParseTest02 (void)
{
    DetectIcmpIdData *iid = NULL;
    iid = DetectIcmpIdParse("  300  ");
    if (iid != NULL && iid->id == htons(300)) {
        DetectIcmpIdFree(iid);
        return 1;
    }
    return 0;
}

/**
 * \test DetectIcmpIdParseTest03 is a test for setting a valid icmp_id value
 *       with quotation marks
 */
int DetectIcmpIdParseTest03 (void)
{
    DetectIcmpIdData *iid = NULL;
    iid = DetectIcmpIdParse("\"300\"");
    if (iid != NULL && iid->id == htons(300)) {
        DetectIcmpIdFree(iid);
        return 1;
    }
    return 0;
}

/**
 * \test DetectIcmpIdParseTest04 is a test for setting a valid icmp_id value
 *       with quotation marks and spaces all around
 */
int DetectIcmpIdParseTest04 (void)
{
    DetectIcmpIdData *iid = NULL;
    iid = DetectIcmpIdParse("   \"   300 \"");
    if (iid != NULL && iid->id == htons(300)) {
        DetectIcmpIdFree(iid);
        return 1;
    }
    return 0;
}

/**
 * \test DetectIcmpIdParseTest05 is a test for setting an invalid icmp_id
 *       value with missing quotation marks
 */
int DetectIcmpIdParseTest05 (void)
{
    DetectIcmpIdData *iid = NULL;
    iid = DetectIcmpIdParse("\"300");
    if (iid == NULL) {
        DetectIcmpIdFree(iid);
        return 1;
    }
    return 0;
}

/**
 * \test DetectIcmpIdMatchTest01 is a test for checking the working of
 *       icmp_id keyword by creating 2 rules and matching a crafted packet
 *       against them. Only the first one shall trigger.
 */
int DetectIcmpIdMatchTest01 (void)
{
    int result = 0;
    Packet *p = NULL;
    Signature *s = NULL;
    ThreadVars th_v;
    DetectEngineThreadCtx *det_ctx = NULL;

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

    p = UTHBuildPacket(NULL, 0, IPPROTO_ICMP);
    p->icmpv4vars.id = htons(21781);

    DetectEngineCtx *de_ctx = DetectEngineCtxInit();
    if (de_ctx == NULL) {
        goto end;
    }

    de_ctx->flags |= DE_QUIET;

    s = de_ctx->sig_list = SigInit(de_ctx, "alert icmp any any -> any any (icmp_id:21781; sid:1;)");
    if (s == NULL) {
        goto end;
    }

    s = s->next = SigInit(de_ctx, "alert icmp any any -> any any (icmp_id:21782; sid:2;)");
    if (s == NULL) {
        goto end;
    }

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

    SigMatchSignatures(&th_v, de_ctx, det_ctx, p);
    if (PacketAlertCheck(p, 1) == 0) {
        printf("sid 1 did not alert, but should have: ");
        goto cleanup;
    } else if (PacketAlertCheck(p, 2)) {
        printf("sid 2 alerted, but should not have: ");
        goto cleanup;
    }

    result = 1;

cleanup:
    SigGroupCleanup(de_ctx);
    SigCleanSignatures(de_ctx);

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

    UTHFreePackets(&p, 1);
end:
    return result;

}

/**
 * \test DetectIcmpIdMatchTest02 is a test for checking the working of
 *       icmp_id keyword by creating 1 rule and matching a crafted packet
 *       against them. The packet is an ICMP packet with no "id" field,
 *       therefore the rule should not trigger.
 */
int DetectIcmpIdMatchTest02 (void)
{
    int result = 0;

    uint8_t raw_icmpv4[] = {
        0x0b, 0x00, 0x8a, 0xdf, 0x00, 0x00, 0x00, 0x00,
        0x45, 0x00, 0x00, 0x14, 0x25, 0x0c, 0x00, 0x00,
        0xff, 0x11, 0x00, 0x00, 0x85, 0x64, 0xea, 0x5b,
        0x51, 0xa6, 0xbb, 0x35, 0x59, 0x8a, 0x5a, 0xe2,
        0x00, 0x14, 0x00, 0x00 };

    Packet *p = PacketGetFromAlloc();
    if (unlikely(p == NULL))
        return 0;
    Signature *s = NULL;
    DecodeThreadVars dtv;
    ThreadVars th_v;
    DetectEngineThreadCtx *det_ctx = NULL;
    IPV4Hdr ip4h;

    memset(&ip4h, 0, sizeof(IPV4Hdr));
    memset(&dtv, 0, sizeof(DecodeThreadVars));
    memset(&th_v, 0, sizeof(ThreadVars));

    FlowInitConfig(FLOW_QUIET);

    p->src.addr_data32[0] = 0x01020304;
    p->dst.addr_data32[0] = 0x04030201;

    ip4h.s_ip_src.s_addr = p->src.addr_data32[0];
    ip4h.s_ip_dst.s_addr = p->dst.addr_data32[0];
    p->ip4h = &ip4h;

    DecodeICMPV4(&th_v, &dtv, p, raw_icmpv4, sizeof(raw_icmpv4), NULL);

    DetectEngineCtx *de_ctx = DetectEngineCtxInit();
    if (de_ctx == NULL) {
        goto end;
    }

    de_ctx->flags |= DE_QUIET;

    s = de_ctx->sig_list = SigInit(de_ctx, "alert icmp any any -> any any (icmp_id:0; sid:1;)");
    if (s == NULL) {
        goto end;
    }

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

    SigMatchSignatures(&th_v, de_ctx, det_ctx, p);
    if (PacketAlertCheck(p, 1)) {
        printf("sid 1 alerted, but should not have: ");
        goto cleanup;
    }

    result = 1;

cleanup:
    SigGroupCleanup(de_ctx);
    SigCleanSignatures(de_ctx);

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

    FlowShutdown();
end:
    SCFree(p);
    return result;
}
#endif /* UNITTESTS */

void DetectIcmpIdRegisterTests (void)
{
#ifdef UNITTESTS
    UtRegisterTest("DetectIcmpIdParseTest01", DetectIcmpIdParseTest01, 1);
    UtRegisterTest("DetectIcmpIdParseTest02", DetectIcmpIdParseTest02, 1);
    UtRegisterTest("DetectIcmpIdParseTest03", DetectIcmpIdParseTest03, 1);
    UtRegisterTest("DetectIcmpIdParseTest04", DetectIcmpIdParseTest04, 1);
    UtRegisterTest("DetectIcmpIdParseTest05", DetectIcmpIdParseTest05, 1);
    UtRegisterTest("DetectIcmpIdMatchTest01", DetectIcmpIdMatchTest01, 1);
    UtRegisterTest("DetectIcmpIdMatchTest02", DetectIcmpIdMatchTest02, 1);
#endif /* UNITTESTS */
}