From a955e4a6233a8fe6341e14f3ee86faa5068497ac Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Markus=20M=C3=A4kel=C3=A4?= <markus.makela@mariadb.com>
Date: Mon, 4 Sep 2017 20:05:08 +0300
Subject: [PATCH] MXS-1346: Only parse text queries

Only text format queries (COM_QUERY, COM_STMT_PREPARE) can be parsed by
the query classifier.

Also fixed invalid use of a NULL value in a string constructor.
---
 .../modules/filter/dbfwfilter/dbfwfilter.cc   | 19 ++++++++++++-----
 .../modules/filter/dbfwfilter/dbfwfilter.hh   |  2 +-
 server/modules/filter/dbfwfilter/rules.cc     | 21 ++++++++++++++-----
 3 files changed, 31 insertions(+), 11 deletions(-)

diff --git a/server/modules/filter/dbfwfilter/dbfwfilter.cc b/server/modules/filter/dbfwfilter/dbfwfilter.cc
index 5cefd7805..a0948924b 100644
--- a/server/modules/filter/dbfwfilter/dbfwfilter.cc
+++ b/server/modules/filter/dbfwfilter/dbfwfilter.cc
@@ -1232,11 +1232,17 @@ static bool command_is_mandatory(const GWBUF *buffer)
 
 static std::string get_sql(GWBUF* buffer)
 {
+    std::string rval;
     char *sql;
     int len;
-    modutil_extract_SQL(buffer, &sql, &len);
-    len = MXS_MIN(len, FW_MAX_SQL_LEN);
-    return std::string(sql, len);
+
+    if (modutil_extract_SQL(buffer, &sql, &len))
+    {
+        len = MXS_MIN(len, FW_MAX_SQL_LEN);
+        rval.assign(sql, len);
+    }
+
+    return rval;
 }
 
 DbfwSession::DbfwSession(Dbfw* instance, MXS_SESSION* session):
@@ -1250,9 +1256,12 @@ DbfwSession::~DbfwSession()
 {
 }
 
-void DbfwSession::set_error(std::string error)
+void DbfwSession::set_error(const char* error)
 {
-    m_error = error;
+    if (error)
+    {
+        m_error = error;
+    }
 }
 
 std::string DbfwSession::get_error()const
diff --git a/server/modules/filter/dbfwfilter/dbfwfilter.hh b/server/modules/filter/dbfwfilter/dbfwfilter.hh
index 99fa9346e..fb4be3679 100644
--- a/server/modules/filter/dbfwfilter/dbfwfilter.hh
+++ b/server/modules/filter/dbfwfilter/dbfwfilter.hh
@@ -174,7 +174,7 @@ public:
     DbfwSession(Dbfw* instance, MXS_SESSION* session);
     ~DbfwSession();
 
-    void set_error(std::string error);
+    void set_error(const char* error);
     std::string get_error() const;
     void clear_error();
     int send_error();
diff --git a/server/modules/filter/dbfwfilter/rules.cc b/server/modules/filter/dbfwfilter/rules.cc
index 09135120f..4d119872e 100644
--- a/server/modules/filter/dbfwfilter/rules.cc
+++ b/server/modules/filter/dbfwfilter/rules.cc
@@ -48,12 +48,23 @@ bool Rule::matches_query(DbfwSession* session, GWBUF* buffer, char** msg) const
 
 bool Rule::matches_query_type(GWBUF* buffer) const
 {
-    qc_query_op_t optype = qc_get_operation(buffer);
+    bool rval = true;
 
-    return on_queries == FW_OP_UNDEFINED ||
-           (on_queries & qc_op_to_fw_op(optype)) ||
-           (MYSQL_IS_COM_INIT_DB(GWBUF_DATA(buffer)) &&
-            (on_queries & FW_OP_CHANGE_DB));
+    if (on_queries != FW_OP_UNDEFINED)
+    {
+        rval = false;
+
+        if (query_is_sql(buffer))
+        {
+            qc_query_op_t optype = qc_get_operation(buffer);
+
+            rval = (on_queries & qc_op_to_fw_op(optype)) ||
+                   (MYSQL_IS_COM_INIT_DB(GWBUF_DATA(buffer)) &&
+                    (on_queries & FW_OP_CHANGE_DB));
+        }
+    }
+
+    return rval;
 }
 
 const std::string& Rule::name() const