Add m_sql_authentication to allow authenticating users against an external SQL database

data/modules.example.conf

@@ -339,6 +339,43 @@ proxyscan
 	reason = "You have an open proxy running on your host (%t:%i:%p)"
 }
 
+/*
+ * m_sql_authentication
+ *
+ * This module allows authenticating users against an external SQL database using a custom
+ * query.
+ */
+#module { name = "m_sql_authentication" }
+m_sql_authentication
+{
+	/* SQL engine to use. Should be configured elsewhere with m_mysql, m_sqlite, etc. */
+	engine = "mysql/main"
+
+	/* Query to execute to authenticate. A non empty result from this query is considered a success,
+	* and the user will be authenticated.
+	* 
+	* @a@ is replaced with the user's account name
+	* @p@ is replaced with the user's password
+	* @n@ is replaced with the user's nickname
+	* @i@ is replaced with the user's IP
+	*
+	* Furthermore, if a field named email is returned from this query the user's email is
+	* set to its value.
+	*/
+	query = "SELECT `email_addr` AS `email` FROM `my_users` WHERE `username` = @u@ AND `password` = MD5(CONCAT('salt', @p@))"
+
+	/*
+	 * Enable to have this module disable /nickserv register.
+	 */
+	disable_ns_register = false
+
+	/*
+	 * The reason to give the users who try to /ns register if
+	 * disable_ns_register is enabled.
+	 */
+	#disable_reason = "To register on this network visit http://some.misconfigured.site/register"
+}
+
 /*
  * m_sqlite
  *