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/* 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 Victor Julien <victor@inliniac.net>
* \author Anoop Saldanha <anoopsaldanha@gmail.com>
*
* Implements the depth keyword.
*/
#include "suricata-common.h"
#include "decode.h"
#include "detect.h"
#include "detect-parse.h"
#include "detect-content.h"
#include "detect-uricontent.h"
#include "detect-byte-extract.h"
#include "flow-var.h"
#include "app-layer.h"
#include "util-byte.h"
#include "util-debug.h"
static int DetectDepthSetup (DetectEngineCtx *, Signature *, char *);
void DetectDepthRegister (void)
{
sigmatch_table[DETECT_DEPTH].name = "depth";
sigmatch_table[DETECT_DEPTH].desc = "designate how many bytes from the beginning of the payload will be checked";
sigmatch_table[DETECT_DEPTH].url = DOC_URL DOC_VERSION "/rules/payload-keywords.html#depth";
sigmatch_table[DETECT_DEPTH].Match = NULL;
sigmatch_table[DETECT_DEPTH].Setup = DetectDepthSetup;
sigmatch_table[DETECT_DEPTH].Free = NULL;
sigmatch_table[DETECT_DEPTH].RegisterTests = NULL;
sigmatch_table[DETECT_DEPTH].flags |= SIGMATCH_PAYLOAD;
}
static int DetectDepthSetup (DetectEngineCtx *de_ctx, Signature *s, char *depthstr)
{
char *str = depthstr;
char dubbed = 0;
SigMatch *pm = NULL;
int ret = -1;
/* Strip leading and trailing "s. */
if (depthstr[0] == '\"') {
str = SCStrdup(depthstr + 1);
if (unlikely(str == NULL))
goto end;
if (strlen(str) && str[strlen(str) - 1] == '\"') {
str[strlen(str) - 1] = '\0';
}
dubbed = 1;
}
/* retrive the sm to apply the depth against */
if (s->list != DETECT_SM_LIST_NOTSET) {
pm = SigMatchGetLastSMFromLists(s, 2, DETECT_CONTENT, s->sm_lists_tail[s->list]);
} else {
pm = SigMatchGetLastSMFromLists(s, 28,
DETECT_CONTENT, s->sm_lists_tail[DETECT_SM_LIST_PMATCH],
DETECT_CONTENT, s->sm_lists_tail[DETECT_SM_LIST_UMATCH],
DETECT_CONTENT, s->sm_lists_tail[DETECT_SM_LIST_HRUDMATCH],
DETECT_CONTENT, s->sm_lists_tail[DETECT_SM_LIST_HCBDMATCH],
DETECT_CONTENT, s->sm_lists_tail[DETECT_SM_LIST_FILEDATA],
DETECT_CONTENT, s->sm_lists_tail[DETECT_SM_LIST_HHDMATCH],
DETECT_CONTENT, s->sm_lists_tail[DETECT_SM_LIST_HRHDMATCH],
DETECT_CONTENT, s->sm_lists_tail[DETECT_SM_LIST_HMDMATCH],
DETECT_CONTENT, s->sm_lists_tail[DETECT_SM_LIST_HCDMATCH],
DETECT_CONTENT, s->sm_lists_tail[DETECT_SM_LIST_HSCDMATCH],
DETECT_CONTENT, s->sm_lists_tail[DETECT_SM_LIST_HSMDMATCH],
DETECT_CONTENT, s->sm_lists_tail[DETECT_SM_LIST_HUADMATCH],
DETECT_CONTENT, s->sm_lists_tail[DETECT_SM_LIST_HHHDMATCH],
DETECT_CONTENT, s->sm_lists_tail[DETECT_SM_LIST_HRHHDMATCH]);
}
if (pm == NULL) {
SCLogError(SC_ERR_DEPTH_MISSING_CONTENT, "depth needs "
"preceding content, uricontent option, http_client_body, "
"http_server_body, http_header option, http_raw_header option, "
"http_method option, http_cookie, http_raw_uri, "
"http_stat_msg, http_stat_code, http_user_agent, "
"http_host, http_raw_host or "
"file_data/dce_stub_data sticky buffer options");
goto end;
}
/* verify other conditions. */
DetectContentData *cd = (DetectContentData *)pm->ctx;
if (cd->flags & DETECT_CONTENT_DEPTH) {
SCLogError(SC_ERR_INVALID_SIGNATURE, "can't use multiple depths for the same content.");
goto end;
}
if ((cd->flags & DETECT_CONTENT_WITHIN) || (cd->flags & DETECT_CONTENT_DISTANCE)) {
SCLogError(SC_ERR_INVALID_SIGNATURE, "can't use a relative "
"keyword like within/distance with a absolute "
"relative keyword like depth/offset for the same "
"content." );
goto end;
}
if (cd->flags & DETECT_CONTENT_NEGATED && cd->flags & DETECT_CONTENT_FAST_PATTERN) {
SCLogError(SC_ERR_INVALID_SIGNATURE, "can't have a relative "
"negated keyword set along with a fast_pattern");
goto end;
}
if (cd->flags & DETECT_CONTENT_FAST_PATTERN_ONLY) {
SCLogError(SC_ERR_INVALID_SIGNATURE, "can't have a relative "
"keyword set along with a fast_pattern:only;");
goto end;
}
if (str[0] != '-' && isalpha((unsigned char)str[0])) {
SigMatch *bed_sm = DetectByteExtractRetrieveSMVar(str, s);
if (bed_sm == NULL) {
SCLogError(SC_ERR_INVALID_SIGNATURE, "unknown byte_extract var "
"seen in depth - %s\n", str);
goto end;
}
cd->depth = ((DetectByteExtractData *)bed_sm->ctx)->local_id;
cd->flags |= DETECT_CONTENT_DEPTH_BE;
} else {
if (ByteExtractStringUint16(&cd->depth, 0, 0, str) != (int)strlen(str))
{
SCLogError(SC_ERR_INVALID_SIGNATURE,
"invalid value for depth: %s", str);
goto end;
}
/* Now update the real limit, as depth is relative to the offset */
cd->depth += cd->offset;
}
cd->flags |= DETECT_CONTENT_DEPTH;
ret = 0;
end:
if (dubbed)
SCFree(str);
return ret;
}
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