Bug#25679

  "Federated Denial of Service"
  Federated storage engine used to attempt to open connections within
  the ::create() and ::open() methods which are invoked while LOCK_open
  mutex is being held by mysqld. As a result, no other client sessions
  can open tables while Federated is attempting to open a connection.
  Long DNS lookup times would stall mysqld's operation and a rogue
  connection string which connects to a remote server which simply
  stalls during handshake can stall mysqld for a much longer period of
  time.
  This patch moves the opening of the connection much later, when the
  federated actually issues queries, by which time the LOCK_open mutex is
  no longer being held.

mysql-test/r/federated.result

@@ -40,17 +40,18 @@ CREATE TABLE federated.t1 (
     )
 ENGINE="FEDERATED" DEFAULT CHARSET=latin1
 CONNECTION='mysql://root@127.0.0.1:SLAVE_PORT/federated/t3';
-ERROR HY000: Can't create federated table. Foreign data src error:  error: 1146  'Table 'federated.t3' doesn't exist'
+SELECT * FROM federated.t1;
+ERROR HY000: The foreign data source you are trying to reference does not exist. Data source error:  error: 1146  'Table 'federated.t3' doesn't exist'
+DROP TABLE federated.t1;
 CREATE TABLE federated.t1 (
 `id` int(20) NOT NULL,
 `name` varchar(32) NOT NULL default ''
     )
 ENGINE="FEDERATED" DEFAULT CHARSET=latin1
 CONNECTION='mysql://user:pass@127.0.0.1:SLAVE_PORT/federated/t1';
-ERROR HY000: Unable to connect to foreign data source: database: 'federated'  username: 'user'  hostname: '127.0.0.1'
-DROP TABLE IF EXISTS federated.t1;
-Warnings:
-Note	1051	Unknown table 't1'
+SELECT * FROM federated.t1;
+ERROR HY000: Unable to connect to foreign data source: Access denied for user 'user'@'localhost' (using password: YES)
+DROP TABLE federated.t1;
 CREATE TABLE federated.t1 (
 `id` int(20) NOT NULL,
 `name` varchar(32) NOT NULL default ''

mysql-test/t/federated.test

@@ -30,25 +30,28 @@ CREATE TABLE federated.t1 (
 
 # test non-existant table
 --replace_result $SLAVE_MYPORT SLAVE_PORT
---error 1434
 eval CREATE TABLE federated.t1 (
     `id` int(20) NOT NULL,
     `name` varchar(32) NOT NULL default ''
     )
   ENGINE="FEDERATED" DEFAULT CHARSET=latin1
   CONNECTION='mysql://root@127.0.0.1:$SLAVE_MYPORT/federated/t3';
+--error 1431
+SELECT * FROM federated.t1;
+DROP TABLE federated.t1;
 
 # test bad user/password 
 --replace_result $SLAVE_MYPORT SLAVE_PORT
---error 1429
 eval CREATE TABLE federated.t1 (
     `id` int(20) NOT NULL,
     `name` varchar(32) NOT NULL default ''
     )
   ENGINE="FEDERATED" DEFAULT CHARSET=latin1
   CONNECTION='mysql://user:pass@127.0.0.1:$SLAVE_MYPORT/federated/t1';
+--error 1429
+SELECT * FROM federated.t1;
+DROP TABLE federated.t1;
 
-DROP TABLE IF EXISTS federated.t1;
 # # correct connection, same named tables
 --replace_result $SLAVE_MYPORT SLAVE_PORT
 eval CREATE TABLE federated.t1 (

sql/ha_federated.h

@@ -182,6 +182,8 @@ class ha_federated: public handler
                                      uint key_len,
                                      ha_rkey_function find_flag,
                                      MYSQL_RES **result);
+  int real_query(const char *query, uint length);
+  int real_connect();
 public:
   ha_federated(TABLE *table_arg);
   ~ha_federated()