dcb.c

dcb_final_free: Router session is not closed anymore when dcb is closed. Router session is shared among all dcbs and is closed and freed with session.
	dcb_connect: dcb's state must be switched fro DCB_STATE_ALLOC to DCB_STATE_DISCONNECTED before dcb_final_free can be called for it.
	dcb_close: poll_remove_dcb encapsulates dcb's state transition in the same way as poll_add_dcb. Removed state modification from dcb_close. Read return value of poll_remove_dcb and log accordingly.
	dcb_set state: remove dassert if dcb_set_state_nomutex returned false. False can be returned indicating that intented change didn't occur but the end state, for example, may be acceptable. Failures in state transitions are asserted in dcb_Set_state_nomutex.

poll.c
	poll_add_dcb: dcb state is now set here to either DCB_STATE_LISTENING or to DCB_STATE_POLLING according to dcb's role. Failures in state setting and in epoll_ctl are detected, logged and handled.
	poll_remove_dcb: Failures in state setting and epoll_ctl are detected, logged, and handled.

mysql_client_server_protocol.h 
	Removed macros MYSQL_FAILED_AUTHENTICATION & MYSQL_SUCCESFUL_AUTHENTICATION as they were not necessary and used with constant values 0 and 1 depending on the case.
	Renamed variable 'conn' to 'protocol' in cases where it meant protocol.

mysql_backend.c
	gw_read_backend_event: In case when there was nothing to read or read failed, backend dcb is closed because situation is assumed to be such that backend server closed its side of the socket. Removed macros MYSQL_FAILED/SUCCESFUL_AUTHENTICATION
	gw_create_backend_connection: Assigned protocol with fd which is connected to backend.
	backend_write_delayqueue: In case where dcb_write fails to write anything, close backend dcb to avoid it getting hanging.

mysql_client.c
	gw_read_client_event: Read return value of routeQuery and if it isn't == 1, call mysql_send_custom_error with client dcb and set client's protocol state to MYSQL_IDLE instead of MYSQL_ROUTING.
	gw_MySQLAccept: Static reply counter was erroneously used as a criteria for jumping to return point where return value was constantly 'success' (=0). Replaced static reply counter with private. Fixed return value in different cases.

mysql_common.c
	gw_receive_backend_auth: Changed to return boolean values indicating of success or failue. Used integers which were assigned to macroed values on the caller side. Added length check before accessing buffer. 

readconnroute.c
	Cut too long lines and removed statements with side effects.

skygw_debug.h
	Added macro STRPROTOCOLSTATE(s) to produce string representation of a given protocol state.

server/modules/protocol/mysql_common.c

@@ -290,34 +290,41 @@ int gw_decode_mysql_server_handshake(MySQLProtocol *conn, uint8_t *payload) {
 	return 0;
 }
 
+
 /**
  * Receive the MySQL authentication packet from backend, packet # is 2
  *
  * @param conn The MySQL protocol structure
- * @return 0 for user authenticated or 1 for authentication failed
+ * @return true if authentication succeed, false otherwise
  */
-int gw_receive_backend_auth(MySQLProtocol *conn) {
-	int rv = 1;
+bool gw_receive_backend_auth(
+        MySQLProtocol *protocol)
+{
 	int n = -1;
-	GWBUF *head = NULL;
-	DCB *dcb = conn->owner_dcb;
+	GWBUF   *head = NULL;
+	DCB     *dcb = protocol->owner_dcb;
 	uint8_t *ptr = NULL;
+        bool    succp = false;
 
-	if ((n = dcb_read(dcb, &head)) != -1) {
-		if (head) {
-			ptr = GWBUF_DATA(head);
-			// check if the auth is SUCCESFUL
-			if (ptr[4] == '\x00') {
-				// Auth is OK 
-				rv = 0;
-			} else {
-				rv = 1;
-			}
-			// consume all the data here
-			head = gwbuf_consume(head, gwbuf_length(head));
-		}
-	}
-	return rv;
+        n = dcb_read(dcb, &head);
+
+	if (n != -1 &&
+            head != NULL &&
+            GWBUF_LENGTH(head) >= 5)
+        {
+                ptr = GWBUF_DATA(head);
+                /**
+                 * 5th byte is 0x0 if successful.
+                 */
+                if (ptr[4] == '\x00') {
+                        succp = true;
+                }
+                /**
+                 * Remove data from buffer.
+                 */
+                head = gwbuf_consume(head, gwbuf_length(head));
+        }
+        return succp;
 }
 
 /**