/system/expressionengine/helpers/version_helper.php

<?php  if ( ! defined('BASEPATH')) exit('No direct script access allowed');

/**
 * ExpressionEngine - by EllisLab
 *
 * @package		ExpressionEngine
 * @author		EllisLab Dev Team
 * @copyright	Copyright (c) 2003 - 2013, EllisLab, Inc.
 * @license		http://ellislab.com/expressionengine/user-guide/license.html
 * @link		http://ellislab.com
 * @since		Version 2.0
 * @filesource
 */
 
// ------------------------------------------------------------------------

/**
 * ExpressionEngine Segment Helper
 *
 * @package		ExpressionEngine
 * @subpackage	Helpers
 * @category	Helpers
 * @author		EllisLab Dev Team
 * @link		http://ellislab.com
 */

// --------------------------------------------------------------------

	/**
	 * EE Version Check function
	 * 
	 * Requests a file from ExpressionEngine.com that informs us what the current available version
	 * of ExpressionEngine.
	 *
	 * @access	private
	 * @return	bool|string
	 */
	function get_version_info()
	{		
		$EE =& get_instance();

		// Attempt to grab the local cached file
		$cached = _check_version_cache();

		$data = '';
		
		if ( ! $cached)
		{
			$details['timestamp'] = time();
			
			$dl_page_url = 'http://versions.ellislab.com/versions_ee2.txt';

			$target = parse_url($dl_page_url);

			$fp = @fsockopen($target['host'], 80, $errno, $errstr, 3);
			
			if (is_resource($fp))
			{
				fputs($fp,"GET ".$dl_page_url." HTTP/1.0\r\n" );
				fputs($fp,"Host: ".$target['host'] . "\r\n" );
				fputs($fp,"User-Agent: EE/EllisLab PHP/\r\n");
				fputs($fp,"If-Modified-Since: Fri, 01 Jan 2004 12:24:04\r\n\r\n");

				$headers = TRUE;

				while ( ! feof($fp))
				{
					$line = fgets($fp, 4096);

					if ($headers === FALSE)
					{
						$data .= $line;
					}
					elseif (trim($line) == '')
					{
						$headers = FALSE;
					}
				}

				fclose($fp);
				
				if ($data !== '')
				{
					// We have a file, now parse & make an array of arrays.
					$data = explode("\n", trim($data));
					
					$version_file = array();
					
					foreach ($data as $d)
					{
						$version_file[] = explode('|', $d);
					}

					// 0 => 
					//   array
					//     0 => string '2.1.0' (length=5)
					//     1 => string '20100805' (length=8)
					//     2 => string 'normal' (length=6)
					
					if ($data === NULL)
					{
						// something's not right...
						$version_file['error'] = TRUE;
					}
				}
				else
				{
					$version_file['error'] = TRUE;
				}
			}
			else
			{
				$version_file['error'] = TRUE;
			}
			
			_write_version_cache($version_file);			
		}
		else
		{
			$version_file = $cached;
		}
		
		// one final check for good measure
		if ( ! _is_valid_version_file($version_file))
		{
			return FALSE;
		}

		if (isset($version_file['error']) &&  $version_file['error'] == TRUE)
		{
			return FALSE;
		}

		return $version_file;
	}
	
	// --------------------------------------------------------------------

	/**
	 * Validate version file
	 * Prototype:
	 *  0 => 
	 *    array
	 *      0 => string '2.1.0' (length=5)
	 *      1 => string '20100805' (length=8)
	 *      2 => string 'normal' (length=6)
	 * 
	 * @access	private
	 * @return	bool
	 */
	function _is_valid_version_file($version_file)
	{
		if ( ! is_array($version_file))
		{
			return FALSE;
		}
		
		foreach ($version_file as $version)
		{
			if ( ! is_array($version) OR count($version) != 3)
			{
				return FALSE;
			}
			
			foreach ($version as $val)
			{
				if ( ! is_string($val))
				{
					return FALSE;
				}
			}
		}
		
		return TRUE;
	}
	
	// --------------------------------------------------------------------
	
	/**
	 * Check EE Version Cache.
	 *
	 * @access	private
	 * @return	bool|string
	 */
	function _check_version_cache()
	{
		$EE =& get_instance();
		$EE->load->helper('file');
		
		// check cache first
		$cache_expire = 60 * 60 * 24;	// only do this once per day
		$contents = read_file(APPPATH.'cache/ee_version/current_version');

		if ($contents !== FALSE)
		{
			$details = @unserialize($contents);

			if (isset($details['timestamp']) && ($details['timestamp'] + $cache_expire) > $EE->localize->now)
			{
				return $details['data'];
			}
			else
			{
				return FALSE;
			}
		}
	}

	// --------------------------------------------------------------------

	/**
	 * Write EE Version Cache
	 *
	 * @param array - details of version needed to be cached.
	 * @return void
	 */
	function _write_version_cache($details)
	{
		$EE =& get_instance();
		$EE->load->helper('file');
		
		$cache_path = $EE->config->item('cache_path');
		
		if (empty($cache_path))
		{
			$cache_path = APPPATH.'cache/';
		}
		
		$cache_path .= 'ee_version/';
		
		if ( ! is_dir($cache_path))
		{
			mkdir($cache_path, DIR_WRITE_MODE);
			@chmod($cache_path, DIR_WRITE_MODE);	
		}
		
		$data = array(
				'timestamp'	=> $EE->localize->now,
				'data' 		=> $details
			);

		if (write_file($cache_path.'current_version', serialize($data)))
		{
			@chmod($cache_path.'current_version', FILE_WRITE_MODE);			
		}		
	}


/* End of file version_helper.php */
/* Location: ./system/expressionengine/helpers/version_helper.php */