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/* 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>
*
* Implements the dotprefix transformation
*/
#include "suricata-common.h"
#include "detect.h"
#include "detect-engine.h"
#include "detect-engine-prefilter.h"
#include "detect-parse.h"
#include "detect-transform-dotprefix.h"
#include "detect-engine-build.h"
#include "util-unittest.h"
#include "util-print.h"
#include "util-memrchr.h"
#include "util-memcpy.h"
static int DetectTransformDotPrefixSetup (DetectEngineCtx *, Signature *, const char *);
#ifdef UNITTESTS
static void DetectTransformDotPrefixRegisterTests(void);
#endif
static void TransformDotPrefix(InspectionBuffer *buffer, void *options);
void DetectTransformDotPrefixRegister(void)
{
sigmatch_table[DETECT_TRANSFORM_DOTPREFIX].name = "dotprefix";
sigmatch_table[DETECT_TRANSFORM_DOTPREFIX].desc =
"modify buffer to extract the dotprefix";
sigmatch_table[DETECT_TRANSFORM_DOTPREFIX].url =
"/rules/transforms.html#dotprefix";
sigmatch_table[DETECT_TRANSFORM_DOTPREFIX].Transform = TransformDotPrefix;
sigmatch_table[DETECT_TRANSFORM_DOTPREFIX].Setup = DetectTransformDotPrefixSetup;
#ifdef UNITTESTS
sigmatch_table[DETECT_TRANSFORM_DOTPREFIX].RegisterTests =
DetectTransformDotPrefixRegisterTests;
#endif
sigmatch_table[DETECT_TRANSFORM_DOTPREFIX].flags |= SIGMATCH_NOOPT;
}
/**
* \internal
* \brief Extract the dotprefix, if any, the last pattern match, either content or uricontent
* \param det_ctx detection engine ctx
* \param s signature
* \param nullstr should be null
* \retval 0 ok
* \retval -1 failure
*/
static int DetectTransformDotPrefixSetup (DetectEngineCtx *de_ctx, Signature *s, const char *nullstr)
{
SCEnter();
int r = DetectSignatureAddTransform(s, DETECT_TRANSFORM_DOTPREFIX, NULL);
SCReturnInt(r);
}
/**
* \brief Return the dotprefix, if any, in the last pattern match.
*
* Input values are modified by prefixing with a ".".
*
* Rule: "alert dns any any -> any any (dns_query; dotprefix; content:".google.com"; sid:1;)"
* 1. hello.google.com --> match
* 2. hey.agoogle.com --> no match
* 3. agoogle.com --> no match
* 4. something.google.com.au --> match
* 5. google.com --> match
*
* To match on the dotprefix only:
* Rule: "alert dns any any -> any any (dns_query; dotprefix; content:".google.com"; endswith; sid:1;)"
*
* 1. hello.google.com --> match
* 2. hey.agoogle.com --> no match
* 3. agoogle.com --> no match
* 4. something.google.com.au --> no match
* 5. google.com --> match
*
* To match on a TLD:
* Rule: "alert dns any any -> any any (dns_query; dotprefix; content:".co.uk"; endswith; sid:1;)"
*
* 1. hello.google.com --> no match
* 2. hey.agoogle.com --> no match
* 3. agoogle.com --> no match
* 4. something.google.co.uk --> match
* 5. google.com --> no match
*/
static void TransformDotPrefix(InspectionBuffer *buffer, void *options)
{
const size_t input_len = buffer->inspect_len;
if (input_len) {
uint8_t output[input_len + 1]; // For the leading '.'
output[0] = '.';
memcpy(&output[1], buffer->inspect, input_len);
InspectionBufferCopy(buffer, output, input_len + 1);
}
}
#ifdef UNITTESTS
static int DetectTransformDotPrefixTest01(void)
{
const uint8_t *input = (const uint8_t *)"example.com";
uint32_t input_len = strlen((char *)input);
const char *result = ".example.com";
uint32_t result_len = strlen((char *)result);
InspectionBuffer buffer;
InspectionBufferInit(&buffer, input_len);
InspectionBufferSetup(NULL, -1, &buffer, input, input_len);
PrintRawDataFp(stdout, buffer.inspect, buffer.inspect_len);
TransformDotPrefix(&buffer, NULL);
PrintRawDataFp(stdout, buffer.inspect, buffer.inspect_len);
FAIL_IF_NOT(buffer.inspect_len == result_len);
FAIL_IF_NOT(strncmp(result, (const char *)buffer.inspect, result_len) == 0);
InspectionBufferFree(&buffer);
PASS;
}
static int DetectTransformDotPrefixTest02(void)
{
const uint8_t *input = (const uint8_t *)"hello.example.com";
uint32_t input_len = strlen((char *)input);
const char *result = ".hello.example.com";
uint32_t result_len = strlen((char *)result);
InspectionBuffer buffer;
InspectionBufferInit(&buffer, input_len);
InspectionBufferSetup(NULL, -1, &buffer, input, input_len);
PrintRawDataFp(stdout, buffer.inspect, buffer.inspect_len);
TransformDotPrefix(&buffer, NULL);
PrintRawDataFp(stdout, buffer.inspect, buffer.inspect_len);
FAIL_IF_NOT(buffer.inspect_len == result_len);
FAIL_IF_NOT(strncmp(result, (const char *)buffer.inspect, result_len) == 0);
InspectionBufferFree(&buffer);
PASS;
}
static int DetectTransformDotPrefixTest03(void)
{
const char rule[] = "alert dns any any -> any any (dns.query; dotprefix; content:\".google.com\"; sid:1;)";
ThreadVars th_v;
DetectEngineThreadCtx *det_ctx = NULL;
memset(&th_v, 0, sizeof(th_v));
DetectEngineCtx *de_ctx = DetectEngineCtxInit();
FAIL_IF_NULL(de_ctx);
Signature *s = DetectEngineAppendSig(de_ctx, rule);
FAIL_IF_NULL(s);
SigGroupBuild(de_ctx);
DetectEngineThreadCtxInit(&th_v, (void *)de_ctx, (void *)&det_ctx);
DetectEngineThreadCtxDeinit(&th_v, (void *)det_ctx);
DetectEngineCtxFree(de_ctx);
PASS;
}
static void DetectTransformDotPrefixRegisterTests(void)
{
UtRegisterTest("DetectTransformDotPrefixTest01", DetectTransformDotPrefixTest01);
UtRegisterTest("DetectTransformDotPrefixTest02", DetectTransformDotPrefixTest02);
UtRegisterTest("DetectTransformDotPrefixTest03", DetectTransformDotPrefixTest03);
}
#endif
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