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/* WITHIN part of the detection engine. */
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/** \file
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* \author Victor Julien <victor@inliniac.net>
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*/
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#include "suricata-common.h"
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#include "decode.h"
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#include "detect.h"
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#include "detect-content.h"
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#include "detect-uricontent.h"
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#include "flow-var.h"
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#include "util-debug.h"
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static int DetectWithinSetup (DetectEngineCtx *, Signature *, char *);
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void DetectWithinRegister (void) {
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sigmatch_table[DETECT_WITHIN].name = "within";
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sigmatch_table[DETECT_WITHIN].Match = NULL;
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sigmatch_table[DETECT_WITHIN].Setup = DetectWithinSetup;
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sigmatch_table[DETECT_WITHIN].Free = NULL;
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sigmatch_table[DETECT_WITHIN].RegisterTests = NULL;
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sigmatch_table[DETECT_WITHIN].flags |= SIGMATCH_PAYLOAD;
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}
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static int DetectWithinSetup (DetectEngineCtx *de_ctx, Signature *s, char *withinstr)
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{
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char *str = withinstr;
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char dubbed = 0;
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/* strip "'s */
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if (withinstr[0] == '\"' && withinstr[strlen(withinstr)-1] == '\"') {
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str = SCStrdup(withinstr+1);
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str[strlen(withinstr)-2] = '\0';
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dubbed = 1;
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}
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if (s->pmatch == NULL) {
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SCLogError(SC_ERR_WITHIN_MISSING_CONTENT, "within needs two preceeding content options");
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goto error;
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}
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/** Search for the first previous DetectContent
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* SigMatch (it can be the same as this one) */
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SigMatch *pm = DetectContentFindPrevApplicableSM(s->pmatch_tail);
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if (pm == NULL || DetectContentHasPrevSMPattern(pm) == NULL) {
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SCLogError(SC_ERR_WITHIN_MISSING_CONTENT, "within needs two preceeding content options");
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goto error;
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}
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DetectContentData *cd = (DetectContentData *)pm->ctx;
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if (cd == NULL) {
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printf("DetectWithinSetup: Unknown previous keyword!\n");
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goto error;
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}
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cd->within = strtol(str, NULL, 10);
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if (cd->within < cd->content_len) {
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SCLogError(SC_ERR_INVALID_SIGNATURE, "within argument \"%d\" is less "
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"than the content length \"%s\" which is invalid, since this "
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"will never match. Invalidating signature", cd->within, cd->content);
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goto error;
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}
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cd->flags |= DETECT_CONTENT_WITHIN;
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if (cd->flags & DETECT_CONTENT_DISTANCE) {
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if (cd->distance > (cd->content_len + cd->within)) {
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cd->within = cd->distance + cd->content_len;
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}
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}
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pm = DetectContentFindPrevApplicableSM(s->pmatch_tail->prev);
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if (pm == NULL) {
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SCLogError(SC_ERR_WITHIN_MISSING_CONTENT, "within needs two preceeding content options");
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goto error;
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}
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/* Set the relative next flag on the prev sigmatch */
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if (pm->type == DETECT_CONTENT) {
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DetectContentData *cd = (DetectContentData *)pm->ctx;
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cd->flags |= DETECT_CONTENT_RELATIVE_NEXT;
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} else {
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printf("DetectWithinSetup: Unknown previous-previous keyword!\n");
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goto error;
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}
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if (dubbed) SCFree(str);
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return 0;
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error:
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if (dubbed) SCFree(str);
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return -1;
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}
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