Disallow all prepared statement commands with dbfwfilter

All binary protocol prepared statements should be rejected by the
dbfwfilter in 2.0 as they aren't supported.

maxscale-system-test/fwf_prepared_stmt.cpp

@@ -21,6 +21,7 @@ int main(int argc, char** argv)
     test.connect_maxscale();
     execute_query_silent(test.conn_rwsplit, "DROP TABLE test.t1");
 
+    test.set_timeout(60);
     test.try_query(test.conn_rwsplit, "CREATE TABLE test.t1(a INT, b INT, c INT)");
     test.try_query(test.conn_rwsplit, "INSERT INTO test.t1 VALUES (1, 1, 1)");
 
@@ -34,6 +35,7 @@ int main(int argc, char** argv)
     test.add_result(execute_query(test.conn_rwsplit, "EXECUTE my_ps2") == 0,
                     "Text protocol execution should fail");
 
+    test.set_timeout(60);
     MYSQL_STMT* stmt = mysql_stmt_init(test.conn_rwsplit);
     const char *query = "SELECT a, b FROM test.t1";
 
@@ -47,7 +49,8 @@ int main(int argc, char** argv)
     test.add_result(!mysql_stmt_prepare(stmt, query, strlen(query)), "Binary protocol preparation should fail");
     mysql_stmt_close(stmt);
 
-    test.try_query(test.conn_rwsplit, "DROP TABLE test.t1");
+    test.repl->connect();
+    test.try_query(test.repl->nodes[0], "DROP TABLE test.t1");
 
     return test.global_result;
 }

server/modules/filter/dbfwfilter/dbfwfilter.c

@@ -2191,6 +2191,23 @@ static bool command_is_mandatory(const GWBUF *buffer)
     }
 }
 
+static bool command_is_prepare(uint8_t command)
+{
+    switch (command)
+    {
+        case MYSQL_COM_STMT_PREPARE:
+        case MYSQL_COM_STMT_EXECUTE:
+        case MYSQL_COM_STMT_SEND_LONG_DATA:
+        case MYSQL_COM_STMT_CLOSE:
+        case MYSQL_COM_STMT_RESET:
+        case MYSQL_COM_STMT_FETCH:
+            return true;
+
+        default:
+            return false;
+    }
+}
+
 /**
  * The routeQuery entry point. This is passed the query buffer
  * to which the filter should be applied. Once processed the
@@ -2209,8 +2226,9 @@ routeQuery(FILTER *instance, void *session, GWBUF *queue)
     DCB *dcb = my_session->session->client_dcb;
     int rval = 0;
     ss_dassert(dcb && dcb->session);
-
     uint32_t type = 0;
+    uint8_t command = 0;
+    gwbuf_copy_data(queue, MYSQL_HEADER_LEN, 1, &command);
 
     if (modutil_is_SQL(queue) || modutil_is_SQL_prepare(queue))
     {
@@ -2228,7 +2246,7 @@ routeQuery(FILTER *instance, void *session, GWBUF *queue)
     }
     else if (QUERY_IS_TYPE(type, QUERY_TYPE_PREPARE_STMT) ||
              QUERY_IS_TYPE(type, QUERY_TYPE_PREPARE_NAMED_STMT) ||
-             modutil_is_SQL_prepare(queue))
+             command_is_prepare(command))
     {
         GWBUF* err = gen_dummy_error(my_session, "This filter does not support "
                                      "prepared statements.");