From 4b157e1556b5c7d5da11b6eb0e4ba72378ce9cfd Mon Sep 17 00:00:00 2001
From: Luis Soares <luis.soares@oracle.com>
Date: Thu, 24 Nov 2011 14:51:18 +0000
Subject: [PATCH] BUG#13427949: CHANGE MASTER TO USER='' (EMPTY USER) CAUSES
 ERRORS ON VALGRING

When passing an empty user to the connect function will cause
valgrind warnings. Seems that the client code is not prepared
to handle empty users. On 5.6 this can even be triggered by
START SLAVE PASSWORD='...'; i.e., without setting USER='...' on
the START SLAVE command (see WL#4143 for details on the new
additional START SLAVE commands).

To fix this, we disallow empty users when configuring the slave
connection parameters (this decision might be revisited if the
client code accepts empty users in the future).

sql/slave.cc:
  We throw an error if an empty user is supplied to the connection
  function.
---
 mysql-test/suite/rpl/r/rpl_connection.result | 11 +++++++++
 mysql-test/suite/rpl/t/rpl_connection.test   | 24 ++++++++++++++++++++
 sql/slave.cc                                 | 14 +++++++++++-
 3 files changed, 48 insertions(+), 1 deletion(-)
 create mode 100644 mysql-test/suite/rpl/r/rpl_connection.result
 create mode 100644 mysql-test/suite/rpl/t/rpl_connection.test

diff --git a/mysql-test/suite/rpl/r/rpl_connection.result b/mysql-test/suite/rpl/r/rpl_connection.result
new file mode 100644
index 00000000000..02a7a36278e
--- /dev/null
+++ b/mysql-test/suite/rpl/r/rpl_connection.result
@@ -0,0 +1,11 @@
+include/master-slave.inc
+[connection master]
+call mtr.add_suppression(".*Invalid .* username when attempting to connect to the master server.*");
+include/stop_slave.inc
+CHANGE MASTER TO MASTER_USER= '', MASTER_PASSWORD= '';
+START SLAVE;
+include/wait_for_slave_io_error.inc [errno=1045, 1593]
+include/stop_slave.inc
+CHANGE MASTER TO MASTER_USER= 'root', MASTER_PASSWORD= '';
+START SLAVE;
+include/rpl_end.inc
diff --git a/mysql-test/suite/rpl/t/rpl_connection.test b/mysql-test/suite/rpl/t/rpl_connection.test
new file mode 100644
index 00000000000..1233e28dc86
--- /dev/null
+++ b/mysql-test/suite/rpl/t/rpl_connection.test
@@ -0,0 +1,24 @@
+--source include/not_embedded.inc
+--source include/master-slave.inc
+--source include/have_binlog_format_mixed.inc
+
+#
+# BUG#13427949: CHANGE MASTER TO USER='' (EMPTY USER) CAUSES ERRORS ON VALGRING 
+#
+
+--connection slave
+call mtr.add_suppression(".*Invalid .* username when attempting to connect to the master server.*");
+
+
+# Assert that we disallow empty users and that no problem
+--source include/stop_slave.inc
+CHANGE MASTER TO MASTER_USER= '', MASTER_PASSWORD= '';
+START SLAVE;
+--let $slave_io_errno= 1045, 1593
+--source include/wait_for_slave_io_error.inc
+--source include/stop_slave.inc
+
+CHANGE MASTER TO MASTER_USER= 'root', MASTER_PASSWORD= '';
+START SLAVE;
+
+--source include/rpl_end.inc 
diff --git a/sql/slave.cc b/sql/slave.cc
index 7a3eee952c3..5c931a79695 100644
--- a/sql/slave.cc
+++ b/sql/slave.cc
@@ -4208,6 +4208,16 @@ static int connect_to_master(THD* thd, MYSQL* mysql, Master_info* mi,
   if (opt_plugin_dir_ptr && *opt_plugin_dir_ptr)
     mysql_options(mysql, MYSQL_PLUGIN_DIR, opt_plugin_dir_ptr);
 
+  /* we disallow empty users */
+  if (mi->user == NULL || mi->user[0] == 0)
+  {
+    mi->report(ERROR_LEVEL, ER_SLAVE_FATAL_ERROR,
+               ER(ER_SLAVE_FATAL_ERROR),
+               "Invalid (empty) username when attempting to "
+               "connect to the master server. Connection attempt "
+               "terminated.");
+    DBUG_RETURN(1);
+  }
   while (!(slave_was_killed = io_slave_killed(thd,mi)) &&
          (reconnect ? mysql_reconnect(mysql) != 0 :
           mysql_real_connect(mysql, mi->host, mi->user, mi->password, 0,
@@ -4336,7 +4346,9 @@ MYSQL *rpl_connect_master(MYSQL *mysql)
   /* This one is not strictly needed but we have it here for completeness */
   mysql_options(mysql, MYSQL_SET_CHARSET_DIR, (char *) charsets_dir);
 
-  if (io_slave_killed(thd, mi)
+  if (mi->user == NULL
+      || mi->user[0] == 0
+      || io_slave_killed(thd, mi)
       || !mysql_real_connect(mysql, mi->host, mi->user, mi->password, 0,
                              mi->port, 0, 0))
   {