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/* Copyright (C) 2023 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 Philippe Antoine <contact@catenacyber.fr>
*
* Implements the header_lowercase transform keyword with option support
*/
#include "suricata-common.h"
#include "detect.h"
#include "detect-engine.h"
#include "detect-parse.h"
#include "detect-transform-header-lowercase.h"
/**
* \internal
* \brief Apply the header_lowercase keyword to the last pattern match
* \param det_ctx detection engine ctx
* \param s signature
* \param optstr options string
* \retval 0 ok
* \retval -1 failure
*/
static int DetectTransformHeaderLowercaseSetup(
DetectEngineCtx *de_ctx, Signature *s, const char *optstr)
{
SCEnter();
int r = DetectSignatureAddTransform(s, DETECT_TRANSFORM_HEADER_LOWERCASE, NULL);
SCReturnInt(r);
}
static void DetectTransformHeaderLowercase(InspectionBuffer *buffer, void *options)
{
const uint8_t *input = buffer->inspect;
const uint32_t input_len = buffer->inspect_len;
if (input_len == 0) {
return;
}
uint8_t output[input_len];
// state 0 is header name, 1 is header value
int state = 0;
for (uint32_t i = 0; i < input_len; i++) {
if (state == 0) {
if (input[i] == ':') {
output[i] = input[i];
state = 1;
} else {
output[i] = u8_tolower(input[i]);
}
} else {
output[i] = input[i];
if (input[i] == '\n') {
state = 0;
}
}
}
InspectionBufferCopy(buffer, output, input_len);
}
void DetectTransformHeaderLowercaseRegister(void)
{
sigmatch_table[DETECT_TRANSFORM_HEADER_LOWERCASE].name = "header_lowercase";
sigmatch_table[DETECT_TRANSFORM_HEADER_LOWERCASE].desc =
"modify buffer via lowercaseing header names";
sigmatch_table[DETECT_TRANSFORM_HEADER_LOWERCASE].url =
"/rules/transforms.html#header_lowercase";
sigmatch_table[DETECT_TRANSFORM_HEADER_LOWERCASE].Transform = DetectTransformHeaderLowercase;
sigmatch_table[DETECT_TRANSFORM_HEADER_LOWERCASE].Setup = DetectTransformHeaderLowercaseSetup;
sigmatch_table[DETECT_TRANSFORM_HEADER_LOWERCASE].flags |= SIGMATCH_NOOPT;
}
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