1 files changed, 366 insertions, 0 deletions
diff --git a/src/detect-mqtt-flags.c b/src/detect-mqtt-flags.c
new file mode 100644
index 0000000..799e166
--- /dev/null
+++ b/src/detect-mqtt-flags.c
@@ -0,0 +1,366 @@
+/* Copyright (C) 2020 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 Sascha Steinbiss <sascha@steinbiss.name>
+ */
+
+#include "suricata-common.h"
+#include "conf.h"
+#include "detect.h"
+#include "detect-parse.h"
+#include "detect-engine.h"
+#include "detect-engine-content-inspection.h"
+#include "detect-mqtt-flags.h"
+#include "util-unittest.h"
+
+#include "rust.h"
+
+#define PARSE_REGEX "(?: *,?!?(?:retain|dup))+"
+static DetectParseRegex parse_regex;
+
+static int mqtt_flags_id = 0;
+
+static int DetectMQTTFlagsMatch(DetectEngineThreadCtx *det_ctx,
+                               Flow *f, uint8_t flags, void *state,
+                               void *txv, const Signature *s,
+                               const SigMatchCtx *ctx);
+static int DetectMQTTFlagsSetup (DetectEngineCtx *, Signature *, const char *);
+void MQTTFlagsRegisterTests(void);
+void DetectMQTTFlagsFree(DetectEngineCtx *de_ctx, void *);
+
+typedef struct DetectMQTTFlagsData_ {
+    MQTTFlagState retain, dup;
+} DetectMQTTFlagsData;
+
+/**
+ * \brief Registration function for mqtt.flags: keyword
+ */
+void DetectMQTTFlagsRegister (void)
+{
+    sigmatch_table[DETECT_AL_MQTT_FLAGS].name = "mqtt.flags";
+    sigmatch_table[DETECT_AL_MQTT_FLAGS].desc = "match MQTT fixed header flags";
+    sigmatch_table[DETECT_AL_MQTT_FLAGS].url = "/rules/mqtt-keywords.html#mqtt-flags";
+    sigmatch_table[DETECT_AL_MQTT_FLAGS].AppLayerTxMatch = DetectMQTTFlagsMatch;
+    sigmatch_table[DETECT_AL_MQTT_FLAGS].Setup = DetectMQTTFlagsSetup;
+    sigmatch_table[DETECT_AL_MQTT_FLAGS].Free  = DetectMQTTFlagsFree;
+#ifdef UNITTESTS
+    sigmatch_table[DETECT_AL_MQTT_FLAGS].RegisterTests = MQTTFlagsRegisterTests;
+#endif
+
+    DetectSetupParseRegexes(PARSE_REGEX, &parse_regex);
+
+    DetectAppLayerInspectEngineRegister2(
+            "mqtt.flags", ALPROTO_MQTT, SIG_FLAG_TOSERVER, 1, DetectEngineInspectGenericList, NULL);
+
+    mqtt_flags_id = DetectBufferTypeGetByName("mqtt.flags");
+}
+
+/**
+ * \internal
+ * \brief Function to match fixed header flags of an MQTT Tx
+ *
+ * \param det_ctx Pointer to the pattern matcher thread.
+ * \param f       Pointer to the current flow.
+ * \param flags   Flags.
+ * \param state   App layer state.
+ * \param txv     Pointer to the transaction.
+ * \param s       Pointer to the Signature.
+ * \param ctx     Pointer to the sigmatch that we will cast into DetectMQTTFlagsData.
+ *
+ * \retval 0 no match.
+ * \retval 1 match.
+ */
+static int DetectMQTTFlagsMatch(DetectEngineThreadCtx *det_ctx,
+                               Flow *f, uint8_t flags, void *state,
+                               void *txv, const Signature *s,
+                               const SigMatchCtx *ctx)
+{
+    const DetectMQTTFlagsData *de = (const DetectMQTTFlagsData *)ctx;
+
+    if (!de)
+        return 0;
+
+    return rs_mqtt_tx_has_flags(txv, de->retain, de->dup);
+}
+
+/**
+ * \internal
+ * \brief This function is used to parse options passed via mqtt.flags: keyword
+ *
+ * \param rawstr Pointer to the user provided options
+ *
+ * \retval de pointer to DetectMQTTFlagsData on success
+ * \retval NULL on failure
+ */
+static DetectMQTTFlagsData *DetectMQTTFlagsParse(const char *rawstr)
+{
+
+    DetectMQTTFlagsData *de = SCCalloc(1, sizeof(DetectMQTTFlagsData));
+    if (unlikely(de == NULL))
+        return NULL;
+
+    pcre2_match_data *match = NULL;
+    int ret = DetectParsePcreExec(&parse_regex, &match, rawstr, 0, 0);
+    if (ret < 1) {
+        SCLogError("invalid flag definition: %s", rawstr);
+        if (match) {
+            pcre2_match_data_free(match);
+        }
+        SCFree(de);
+        return NULL;
+    }
+
+    de->retain = de->dup = MQTT_DONT_CARE;
+
+    char copy[strlen(rawstr)+1];
+    strlcpy(copy, rawstr, sizeof(copy));
+    char *xsaveptr = NULL;
+
+    /* Iterate through comma-separated string... */
+    char *flagv = strtok_r(copy, ",", &xsaveptr);
+    while (flagv != NULL) {
+        /* skip blanks */
+        while (*flagv != '\0' && isblank(*flagv)) {
+            flagv++;
+        }
+        if (strlen(flagv) < 2) {
+            /* flags have a minimum length */
+            SCLogError("malformed flag value: %s", flagv);
+            goto error;
+        }  else {
+            int offset = 0;
+            MQTTFlagState fs_to_set = MQTT_MUST_BE_SET;
+            if (flagv[0] == '!') {
+                /* negated flag */
+                offset = 1;  /* skip negation operator during comparison */
+                fs_to_set = MQTT_CANT_BE_SET;
+            }
+            if (strcmp(flagv+offset, "dup") == 0) {
+                if (de->dup != MQTT_DONT_CARE) {
+                    SCLogError("duplicate flag definition: %s", flagv);
+                    goto error;
+                }
+                de->dup = fs_to_set;
+            } else if (strcmp(flagv+offset, "retain") == 0) {
+                if (de->retain != MQTT_DONT_CARE) {
+                    SCLogError("duplicate flag definition: %s", flagv);
+                    goto error;
+                }
+                de->retain = fs_to_set;
+            } else {
+                SCLogError("invalid flag definition: %s", flagv);
+                goto error;
+            }
+        }
+        flagv = strtok_r(NULL, ",", &xsaveptr);
+    }
+
+    pcre2_match_data_free(match);
+    return de;
+
+error:
+    if (match) {
+        pcre2_match_data_free(match);
+    }
+    if (de)
+        SCFree(de);
+    return NULL;
+}
+
+/**
+ * \internal
+ * \brief this function is used to add the parsed type query into the current signature
+ *
+ * \param de_ctx pointer to the Detection Engine Context
+ * \param s pointer to the Current Signature
+ * \param rawstr pointer to the user provided options
+ *
+ * \retval 0 on Success
+ * \retval -1 on Failure
+ */
+static int DetectMQTTFlagsSetup(DetectEngineCtx *de_ctx, Signature *s, const char *rawstr)
+{
+    DetectMQTTFlagsData *de = NULL;
+    SigMatch *sm = NULL;
+
+    if (DetectSignatureSetAppProto(s, ALPROTO_MQTT) < 0)
+        return -1;
+
+    de = DetectMQTTFlagsParse(rawstr);
+    if (de == NULL)
+        goto error;
+
+    sm = SigMatchAlloc();
+    if (sm == NULL)
+        goto error;
+
+    sm->type = DETECT_AL_MQTT_FLAGS;
+    sm->ctx = (SigMatchCtx *)de;
+
+    SigMatchAppendSMToList(s, sm, mqtt_flags_id);
+
+    return 0;
+
+error:
+    if (de != NULL)
+        SCFree(de);
+    if (sm != NULL)
+        SCFree(sm);
+    return -1;
+}
+
+/**
+ * \internal
+ * \brief this function will free memory associated with DetectMQTTFlagsData
+ *
+ * \param de pointer to DetectMQTTFlagsData
+ */
+void DetectMQTTFlagsFree(DetectEngineCtx *de_ctx, void *de_ptr)
+{
+    if (de_ptr != NULL)
+        SCFree(de_ptr);
+}
+
+/*
+ * ONLY TESTS BELOW THIS COMMENT
+ */
+
+#ifdef UNITTESTS
+/**
+ * \test MQTTFlagsTestParse01 is a test for a valid value
+ *
+ *  \retval 1 on success
+ *  \retval 0 on failure
+ */
+static int MQTTFlagsTestParse01 (void)
+{
+    DetectMQTTFlagsData *de = NULL;
+
+    de = DetectMQTTFlagsParse("retain");
+    FAIL_IF_NULL(de);
+    DetectMQTTFlagsFree(NULL, de);
+
+    de = DetectMQTTFlagsParse("dup");
+    FAIL_IF_NULL(de);
+    DetectMQTTFlagsFree(NULL, de);
+
+    de = DetectMQTTFlagsParse("retain,dup");
+    FAIL_IF_NULL(de);
+    DetectMQTTFlagsFree(NULL, de);
+
+    de = DetectMQTTFlagsParse("dup, retain");
+    FAIL_IF_NULL(de);
+    DetectMQTTFlagsFree(NULL, de);
+
+    PASS;
+}
+
+/**
+ * \test MQTTFlagsTestParse02 is a test for a valid value
+ *
+ *  \retval 1 on success
+ *  \retval 0 on failure
+ */
+static int MQTTFlagsTestParse02 (void)
+{
+    DetectMQTTFlagsData *de = NULL;
+    de = DetectMQTTFlagsParse("retain,!dup");
+    FAIL_IF_NULL(de);
+    DetectMQTTFlagsFree(NULL, de);
+
+    PASS;
+}
+
+/**
+ * \test MQTTFlagsTestParse03 is a test for an invalid value
+ *
+ *  \retval 1 on success
+ *  \retval 0 on failure
+ */
+static int MQTTFlagsTestParse03 (void)
+{
+    DetectMQTTFlagsData *de = NULL;
+    de = DetectMQTTFlagsParse("ref");
+    if (de) {
+        DetectMQTTFlagsFree(NULL, de);
+        FAIL;
+    }
+
+    PASS;
+}
+
+/**
+ * \test MQTTFlagsTestParse04 is a test for an invalid value
+ *
+ *  \retval 1 on success
+ *  \retval 0 on failure
+ */
+static int MQTTFlagsTestParse04 (void)
+{
+    DetectMQTTFlagsData *de = NULL;
+    de = DetectMQTTFlagsParse("dup,!");
+    if (de) {
+        DetectMQTTFlagsFree(NULL, de);
+        FAIL;
+    }
+
+    PASS;
+}
+
+/**
+ * \test MQTTFlagsTestParse05 is a test for an invalid value
+ *
+ *  \retval 1 on success
+ *  \retval 0 on failure
+ */
+static int MQTTFlagsTestParse05 (void)
+{
+    DetectMQTTFlagsData *de = NULL;
+    de = DetectMQTTFlagsParse("dup,!dup");
+    if (de) {
+        DetectMQTTFlagsFree(NULL, de);
+        FAIL;
+    }
+
+    de = DetectMQTTFlagsParse("!retain,retain");
+    if (de) {
+        DetectMQTTFlagsFree(NULL, de);
+        FAIL;
+    }
+
+    PASS;
+}
+
+
+#endif /* UNITTESTS */
+
+/**
+ * \brief this function registers unit tests for MQTTFlags
+ */
+void MQTTFlagsRegisterTests(void)
+{
+#ifdef UNITTESTS
+    UtRegisterTest("MQTTFlagsTestParse01", MQTTFlagsTestParse01);
+    UtRegisterTest("MQTTFlagsTestParse02", MQTTFlagsTestParse02);
+    UtRegisterTest("MQTTFlagsTestParse03", MQTTFlagsTestParse03);
+    UtRegisterTest("MQTTFlagsTestParse04", MQTTFlagsTestParse04);
+    UtRegisterTest("MQTTFlagsTestParse05", MQTTFlagsTestParse05);
+#endif /* UNITTESTS */
+}