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261 lines
7.9 KiB
C
261 lines
7.9 KiB
C
/* Copyright (C) 2019 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 Mats Klepsland <mats.klepsland@gmail.com>
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*
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* Implements support for tls.certs keyword.
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*/
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#include "suricata-common.h"
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#include "threads.h"
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#include "debug.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 "detect-engine-mpm.h"
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#include "detect-engine-prefilter.h"
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#include "detect-engine-content-inspection.h"
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#include "detect-content.h"
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#include "detect-pcre.h"
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#include "detect-tls-certs.h"
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#include "flow.h"
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#include "flow-util.h"
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#include "flow-var.h"
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#include "util-debug.h"
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#include "util-unittest.h"
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#include "util-spm.h"
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#include "util-print.h"
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#include "stream-tcp.h"
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#include "app-layer.h"
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#include "app-layer-ssl.h"
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#include "util-unittest.h"
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#include "util-unittest-helper.h"
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static int DetectTlsCertsSetup(DetectEngineCtx *, Signature *, const char *);
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#ifdef UNITTESTS
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static void DetectTlsCertsRegisterTests(void);
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#endif
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static int DetectEngineInspectTlsCerts(DetectEngineCtx *de_ctx,
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DetectEngineThreadCtx *det_ctx,
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const DetectEngineAppInspectionEngine *engine,
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const Signature *s, Flow *f, uint8_t flags, void *alstate, void *txv,
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uint64_t tx_id);
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static int PrefilterMpmTlsCertsRegister(DetectEngineCtx *de_ctx,
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SigGroupHead *sgh, MpmCtx *mpm_ctx,
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const DetectBufferMpmRegistery *mpm_reg, int list_id);
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static int g_tls_certs_buffer_id = 0;
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struct TlsCertsGetDataArgs {
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int local_id; /**< used as index into thread inspect array */
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SSLCertsChain *cert;
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};
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typedef struct PrefilterMpmTlsCerts {
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int list_id;
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const MpmCtx *mpm_ctx;
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const DetectEngineTransforms *transforms;
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} PrefilterMpmTlsCerts;
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/**
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* \brief Registration function for keyword: tls.certs
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*/
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void DetectTlsCertsRegister(void)
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{
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sigmatch_table[DETECT_AL_TLS_CERTS].name = "tls.certs";
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sigmatch_table[DETECT_AL_TLS_CERTS].desc = "content modifier to match the TLS certificate sticky buffer";
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sigmatch_table[DETECT_AL_TLS_CERTS].url = DOC_URL DOC_VERSION "/rules/tls-keywords.html#tls-certs";
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sigmatch_table[DETECT_AL_TLS_CERTS].Setup = DetectTlsCertsSetup;
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#ifdef UNITTESTS
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sigmatch_table[DETECT_AL_TLS_CERTS].RegisterTests = DetectTlsCertsRegisterTests;
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#endif
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sigmatch_table[DETECT_AL_TLS_CERTS].flags |= SIGMATCH_NOOPT;
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sigmatch_table[DETECT_AL_TLS_CERTS].flags |= SIGMATCH_INFO_STICKY_BUFFER;
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DetectAppLayerInspectEngineRegister2("tls.certs", ALPROTO_TLS,
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SIG_FLAG_TOCLIENT, TLS_STATE_CERT_READY,
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DetectEngineInspectTlsCerts, NULL);
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DetectAppLayerMpmRegister2("tls.certs", SIG_FLAG_TOCLIENT, 2,
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PrefilterMpmTlsCertsRegister, NULL, ALPROTO_TLS,
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TLS_STATE_CERT_READY);
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DetectBufferTypeSetDescriptionByName("tls.certs", "TLS certificate");
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g_tls_certs_buffer_id = DetectBufferTypeGetByName("tls.certs");
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}
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/**
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* \brief This function setup the tls.certs modifier keyword
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*
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* \param de_ctx Pointer to the Detect Engine Context
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* \param s Pointer to the Signature to which the keyword belongs
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* \param str Should hold an empty string always
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*
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* \retval 0 On success
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* \retval -1 On failure
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*/
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static int DetectTlsCertsSetup(DetectEngineCtx *de_ctx, Signature *s,
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const char *str)
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{
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if (DetectBufferSetActiveList(s, g_tls_certs_buffer_id) < 0)
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return -1;
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if (DetectSignatureSetAppProto(s, ALPROTO_TLS) < 0)
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return -1;
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return 0;
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}
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static InspectionBuffer *TlsCertsGetData(DetectEngineThreadCtx *det_ctx,
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const DetectEngineTransforms *transforms, Flow *f,
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struct TlsCertsGetDataArgs *cbdata, int list_id)
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{
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SCEnter();
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InspectionBufferMultipleForList *fb = InspectionBufferGetMulti(det_ctx, list_id);
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InspectionBuffer *buffer = InspectionBufferMultipleForListGet(fb, cbdata->local_id);
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if (buffer == NULL)
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return NULL;
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const SSLState *ssl_state = (SSLState *)f->alstate;
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if (TAILQ_EMPTY(&ssl_state->server_connp.certs)) {
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return NULL;
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}
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if (cbdata->cert == NULL) {
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cbdata->cert = TAILQ_FIRST(&ssl_state->server_connp.certs);
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} else {
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cbdata->cert = TAILQ_NEXT(cbdata->cert, next);
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}
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if (cbdata->cert == NULL) {
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return NULL;
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}
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InspectionBufferSetup(buffer, cbdata->cert->cert_data,
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cbdata->cert->cert_len);
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InspectionBufferApplyTransforms(buffer, transforms);
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SCReturnPtr(buffer, "InspectionBuffer");
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}
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static int DetectEngineInspectTlsCerts(DetectEngineCtx *de_ctx,
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DetectEngineThreadCtx *det_ctx,
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const DetectEngineAppInspectionEngine *engine,
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const Signature *s, Flow *f, uint8_t flags, void *alstate, void *txv,
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uint64_t tx_id)
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{
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const DetectEngineTransforms *transforms = NULL;
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if (!engine->mpm) {
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transforms = engine->v2.transforms;
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}
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struct TlsCertsGetDataArgs cbdata = { 0, NULL };
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while (1)
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{
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InspectionBuffer *buffer = TlsCertsGetData(det_ctx, transforms, f,
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&cbdata, engine->sm_list);
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if (buffer == NULL || buffer->inspect == NULL)
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break;
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det_ctx->buffer_offset = 0;
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det_ctx->discontinue_matching = 0;
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det_ctx->inspection_recursion_counter = 0;
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const int match = DetectEngineContentInspection(de_ctx, det_ctx, s, engine->smd,
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NULL, f, (uint8_t *)buffer->inspect,
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buffer->inspect_len,
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buffer->inspect_offset, DETECT_CI_FLAGS_SINGLE,
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DETECT_ENGINE_CONTENT_INSPECTION_MODE_STATE);
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if (match == 1) {
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return DETECT_ENGINE_INSPECT_SIG_MATCH;
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}
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cbdata.local_id++;
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}
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return DETECT_ENGINE_INSPECT_SIG_NO_MATCH;
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}
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static void PrefilterTxTlsCerts(DetectEngineThreadCtx *det_ctx,
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const void *pectx, Packet *p, Flow *f, void *txv,
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const uint64_t idx, const uint8_t flags)
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{
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SCEnter();
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const PrefilterMpmTlsCerts *ctx = (const PrefilterMpmTlsCerts *)pectx;
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const MpmCtx *mpm_ctx = ctx->mpm_ctx;
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const int list_id = ctx->list_id;
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struct TlsCertsGetDataArgs cbdata = { 0, NULL };
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while (1)
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{
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InspectionBuffer *buffer = TlsCertsGetData(det_ctx, ctx->transforms,
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f, &cbdata, list_id);
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if (buffer == NULL)
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break;
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if (buffer->inspect_len >= mpm_ctx->minlen) {
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(void)mpm_table[mpm_ctx->mpm_type].Search(mpm_ctx,
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&det_ctx->mtcu, &det_ctx->pmq,
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buffer->inspect, buffer->inspect_len);
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}
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cbdata.local_id++;
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}
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}
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static void PrefilterMpmTlsCertsFree(void *ptr)
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{
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SCFree(ptr);
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}
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static int PrefilterMpmTlsCertsRegister(DetectEngineCtx *de_ctx,
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SigGroupHead *sgh, MpmCtx *mpm_ctx,
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const DetectBufferMpmRegistery *mpm_reg, int list_id)
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{
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PrefilterMpmTlsCerts *pectx = SCCalloc(1, sizeof(*pectx));
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if (pectx == NULL)
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return -1;
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pectx->list_id = list_id;
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pectx->mpm_ctx = mpm_ctx;
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pectx->transforms = &mpm_reg->transforms;
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return PrefilterAppendTxEngine(de_ctx, sgh, PrefilterTxTlsCerts,
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mpm_reg->app_v2.alproto, mpm_reg->app_v2.tx_min_progress,
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pectx, PrefilterMpmTlsCertsFree, mpm_reg->name);
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}
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#ifdef UNITTESTS
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#include "tests/detect-tls-certs.c"
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#endif
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