MXS-1267: Use local client in tee

The tee filter now uses the local client class to clone the queries. This
imposes some restrictions on how the filter can be used but also makes
MaxScale as a whole more robust.

Documentation/Filters/Tee-Filter.md

@@ -6,12 +6,15 @@ The tee filter is a "plumbing" fitting in the MariaDB MaxScale filter toolkit.
 It can be used in a filter pipeline of a service to make copies of requests from
 the client and send the copies to another service within MariaDB MaxScale.
 
+**Please Note:** Starting with MaxScale 2.2.0, any client that connects to a
+  service which uses a tee filter will require a grant for the loopback address,
+  i.e. `127.0.0.1`.
+
 ## Configuration
 
 The configuration block for the TEE filter requires the minimal filter
 parameters in its section within the MaxScale configuration file. The service to
-send the duplicates to must be defined. Currently the tee filter does not
-support multi-statements.
+send the duplicates to must be defined.
 
 ```
 [DataMartFilter]

server/modules/filter/tee/CMakeLists.txt

@@ -1,4 +1,4 @@
-add_library(tee SHARED tee.cc)
-target_link_libraries(tee maxscale-common)
+add_library(tee SHARED tee.cc local_client.cc)
+target_link_libraries(tee maxscale-common MySQLCommon)
 set_target_properties(tee PROPERTIES VERSION "1.0.0")
 install_module(tee core)

server/modules/filter/tee/local_client.cc

@@ -34,10 +34,10 @@ LocalClient::LocalClient(MXS_SESSION* session, int fd):
 {
     MXS_POLL_DATA::handler = LocalClient::poll_handler;
     MySQLProtocol* client = (MySQLProtocol*)m_session->client_dcb->protocol;
-    m_proto = {};
-    m_proto.charset = client->charset;
-    m_proto.client_capabilities = client->client_capabilities;
-    m_proto.extra_capabilities = client->extra_capabilities;
+    m_protocol = {};
+    m_protocol.charset = client->charset;
+    m_protocol.client_capabilities = client->client_capabilities;
+    m_protocol.extra_capabilities = client->extra_capabilities;
 }
 
 LocalClient::~LocalClient()
@@ -48,7 +48,7 @@ LocalClient::~LocalClient()
     }
 }
 
-bool LocalClient::query(GWBUF* buffer)
+bool LocalClient::queue_query(GWBUF* buffer)
 {
     GWBUF* my_buf = gwbuf_clone(buffer);
 
@@ -82,9 +82,9 @@ void LocalClient::process(uint32_t events)
         {
             if (m_state == VC_WAITING_HANDSHAKE)
             {
-                if (gw_decode_mysql_server_handshake(&m_proto, GWBUF_DATA(buf) + MYSQL_HEADER_LEN) == 0)
+                if (gw_decode_mysql_server_handshake(&m_protocol, GWBUF_DATA(buf) + MYSQL_HEADER_LEN) == 0)
                 {
-                    GWBUF* response = gw_generate_auth_response(m_session, &m_proto, false, false);
+                    GWBUF* response = gw_generate_auth_response(m_session, &m_protocol, false, false);
                     m_queue.push_front(response);
                     m_state = VC_RESPONSE_SENT;
                 }

server/modules/filter/tee/local_client.hh

@@ -46,7 +46,7 @@ public:
      *
      * @return True if query was successfully queued
      */
-    bool query(GWBUF* buffer);
+    bool queue_query(GWBUF* buffer);
 
 private:
     LocalClient(MXS_SESSION* session, int fd);
@@ -71,5 +71,5 @@ private:
     size_t                  m_expected_bytes;
     std::deque<mxs::Buffer> m_queue;
     MXS_SESSION*            m_session;
-    MySQLProtocol           m_proto;
+    MySQLProtocol           m_protocol;
 };