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219 lines
7.1 KiB
C
219 lines
7.1 KiB
C
/* Copyright (C) 2007-2023 Open Information Security Foundation
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*
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* You can copy, redistribute or modify this Program under the terms of
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* the GNU General Public License version 2 as published by the Free
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* Software Foundation.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* version 2 along with this program; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
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* 02110-1301, USA.
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*/
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/**
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* \file
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*
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* \author Victor Julien <victor@inliniac.net>
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* \author Anoop Saldanha <anoopsaldanha@gmail.com>
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*
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* Implements the distance keyword
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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-parse.h"
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#include "detect-engine.h"
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#include "app-layer.h"
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#include "detect-content.h"
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#include "detect-uricontent.h"
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#include "detect-pcre.h"
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#include "detect-byte.h"
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#include "detect-byte-extract.h"
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#include "detect-distance.h"
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#include "flow-var.h"
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#include "util-byte.h"
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#include "util-debug.h"
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#include "util-unittest.h"
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#include "detect-bytejump.h"
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#include "util-unittest-helper.h"
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static int DetectDistanceSetup(DetectEngineCtx *, Signature *, const char *);
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#ifdef UNITTESTS
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static void DetectDistanceRegisterTests(void);
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#endif
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void DetectDistanceRegister(void)
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{
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sigmatch_table[DETECT_DISTANCE].name = "distance";
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sigmatch_table[DETECT_DISTANCE].desc = "indicates a relation between this content keyword and the content preceding it";
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sigmatch_table[DETECT_DISTANCE].url = "/rules/payload-keywords.html#distance";
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sigmatch_table[DETECT_DISTANCE].Match = NULL;
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sigmatch_table[DETECT_DISTANCE].Setup = DetectDistanceSetup;
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sigmatch_table[DETECT_DISTANCE].Free = NULL;
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#ifdef UNITTESTS
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sigmatch_table[DETECT_DISTANCE].RegisterTests = DetectDistanceRegisterTests;
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#endif
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}
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static int DetectDistanceSetup (DetectEngineCtx *de_ctx, Signature *s,
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const char *distancestr)
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{
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const char *str = distancestr;
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/* retrieve the sm to apply the distance against */
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SigMatch *pm = DetectGetLastSMFromLists(s, DETECT_CONTENT, -1);
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if (pm == NULL) {
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SCLogError("distance needs "
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"preceding content, uricontent option, http_client_body, "
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"http_server_body, http_header option, http_raw_header option, "
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"http_method option, http_cookie, http_raw_uri, "
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"http_stat_msg, http_stat_code, http_user_agent or "
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"file_data/dce_stub_data sticky buffer option");
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return -1;
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}
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/* verify other conditions */
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DetectContentData *cd = (DetectContentData *)pm->ctx;
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if (cd->flags & DETECT_CONTENT_DISTANCE) {
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SCLogError("can't use multiple distances for the same content.");
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return -1;
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}
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if ((cd->flags & DETECT_CONTENT_DEPTH) || (cd->flags & DETECT_CONTENT_OFFSET)) {
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SCLogError("can't use a relative "
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"keyword like within/distance with a absolute "
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"relative keyword like depth/offset for the same "
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"content.");
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return -1;
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}
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if (cd->flags & DETECT_CONTENT_NEGATED && cd->flags & DETECT_CONTENT_FAST_PATTERN) {
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SCLogError("can't have a relative "
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"negated keyword set along with a fast_pattern");
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return -1;
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}
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if (cd->flags & DETECT_CONTENT_FAST_PATTERN_ONLY) {
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SCLogError("can't have a relative "
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"keyword set along with a fast_pattern:only;");
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return -1;
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}
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if (str[0] != '-' && isalpha((unsigned char)str[0])) {
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DetectByteIndexType index;
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if (!DetectByteRetrieveSMVar(str, s, -1, &index)) {
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SCLogError("unknown byte_ keyword var "
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"seen in distance - %s",
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str);
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return -1;
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}
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cd->distance = index;
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cd->flags |= DETECT_CONTENT_DISTANCE_VAR;
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} else {
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if ((StringParseI32RangeCheck(&cd->distance, 0, 0, str, -DETECT_CONTENT_VALUE_MAX,
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DETECT_CONTENT_VALUE_MAX) < 0)) {
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SCLogError("invalid value for distance: %s", str);
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return -1;
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}
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}
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cd->flags |= DETECT_CONTENT_DISTANCE;
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SigMatch *prev_pm = DetectGetLastSMByListPtr(s, pm->prev,
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DETECT_CONTENT, DETECT_PCRE, -1);
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if (prev_pm == NULL) {
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return 0;
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}
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if (prev_pm->type == DETECT_CONTENT) {
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DetectContentData *prev_cd = (DetectContentData *)prev_pm->ctx;
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if (prev_cd->flags & DETECT_CONTENT_FAST_PATTERN_ONLY) {
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SCLogError("previous keyword "
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"has a fast_pattern:only; set. Can't "
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"have relative keywords around a fast_pattern "
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"only content");
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return -1;
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}
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if ((cd->flags & DETECT_CONTENT_NEGATED) == 0) {
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prev_cd->flags |= DETECT_CONTENT_DISTANCE_NEXT;
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} else {
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prev_cd->flags |= DETECT_CONTENT_RELATIVE_NEXT;
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}
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} else if (prev_pm->type == DETECT_PCRE) {
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DetectPcreData *pd = (DetectPcreData *)prev_pm->ctx;
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pd->flags |= DETECT_PCRE_RELATIVE_NEXT;
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}
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return 0;
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}
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#ifdef UNITTESTS
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static int DetectDistanceTest01(void)
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{
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DetectEngineCtx *de_ctx = DetectEngineCtxInit();
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FAIL_IF_NULL(de_ctx);
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de_ctx->flags |= DE_QUIET;
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Signature *s = DetectEngineAppendSig(de_ctx,
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"alert tcp any any -> any any (content:\"|AA BB|\"; content:\"|CC DD EE FF 00 11 22 33 "
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"44 55 66 77 88 99 AA BB CC DD EE|\"; distance: 4; within: 19; sid:1; rev:1;)");
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FAIL_IF_NULL(s);
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SigMatch *sm = de_ctx->sig_list->init_data->smlists[DETECT_SM_LIST_PMATCH];
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FAIL_IF_NULL(sm);
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sm = sm->next;
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FAIL_IF_NULL(sm);
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DetectContentData *co = (DetectContentData *)sm->ctx;
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FAIL_IF_NULL(co);
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FAIL_IF_NOT(co->distance = 4);
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/* within needs to be 23: distance + content_len as Snort auto fixes this */
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FAIL_IF_NOT(co->within = 19);
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DetectEngineCtxFree(de_ctx);
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PASS;
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}
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/**
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* \test DetectDistanceTestPacket01 is a test to check matches of
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* distance works, if the previous keyword is byte_jump and content
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* (bug 163)
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*/
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static int DetectDistanceTestPacket01 (void)
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{
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uint8_t buf[] = { 0x01, 0x00, 0x00, 0x00, 0x00, 0x00 };
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uint16_t buflen = sizeof(buf);
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Packet *p = UTHBuildPacket((uint8_t *)buf, buflen, IPPROTO_TCP);
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FAIL_IF_NULL(p);
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char sig[] = "alert tcp any any -> any any (msg:\"suricata test\"; "
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"byte_jump:1,2; content:\"|00|\"; "
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"within:1; distance:2; sid:98711212; rev:1;)";
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p->flowflags = FLOW_PKT_ESTABLISHED | FLOW_PKT_TOCLIENT;
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FAIL_IF_NOT(UTHPacketMatchSig(p, sig));
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UTHFreePacket(p);
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PASS;
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}
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static void DetectDistanceRegisterTests(void)
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{
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UtRegisterTest("DetectDistanceTest01 -- distance / within mix",
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DetectDistanceTest01);
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UtRegisterTest("DetectDistanceTestPacket01", DetectDistanceTestPacket01);
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}
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#endif /* UNITTESTS */
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