<?php
/**
 * Piwik - Open source web analytics
 *
 * @link http://piwik.org
 * @license http://www.gnu.org/licenses/gpl-3.0.html Gpl v3 or later
 * @version $Id$
 *
 * @category Piwik
 * @package Piwik
 */

/**
 * Server-side http client to retrieve content from remote servers, and optionally save to a local file.
 * Used to check for the latest Piwik version and download updates.
 *
 * @package Piwik
 */
class Piwik_Http
{
	/**
	 * Get "best" available transport method for sendHttpRequest() calls.
	 *
	 * @return string
	 */
	static public function getTransportMethod()
	{
		$method = 'curl';
		if(!extension_loaded('curl'))
		{
			$method = 'stream';
			if(@ini_get('allow_url_fopen') != '1')
			{
				$method = 'socket';
				if(!function_exists('fsockopen'))
				{
					return null;
				}
			}
		}
		return $method;
	}

	/**
	 * Sends http request ensuring the request will fail before $timeout seconds
	 *
	 * If no $destinationPath is specified, the trimmed response (without header) is returned as a string.
	 * If a $destinationPath is specified, the response (without header) is saved to a file.
	 *
	 * @param string $aUrl
	 * @param int $timeout
	 * @param string $userAgent
	 * @param string $destinationPath
	 * @param int $followDepth
	 * @return bool true (or string) on success; false on HTTP response error code (1xx or 4xx)
	 * @throws Exception for all other errors
	 */
	static public function sendHttpRequest($aUrl, $timeout, $userAgent = null, $destinationPath = null, $followDepth = 0)
	{
		// create output file
		$file = null;
		if($destinationPath)
		{
			if (($file = @fopen($destinationPath, 'wb')) === false || !is_resource($file))
			{
				throw new Exception('Error while creating the file: ' . $destinationPath);
			}
		}

		return self::sendHttpRequestBy(self::getTransportMethod(), $aUrl, $timeout, $userAgent, $destinationPath, $file, $followDepth); 			
	}

	/**
	 * Sends http request using the specified transport method
	 *
	 * @param string $method
	 * @param string $aUrl
	 * @param int $timeout
	 * @param string $userAgent
	 * @param string $destinationPath
	 * @param resource $file
	 * @param int $followDepth
	 * @return bool true (or string) on success; false on HTTP response error code (1xx or 4xx)
	 * @throws Exception for all other errors
	 */
	static public function sendHttpRequestBy($method = 'socket', $aUrl, $timeout, $userAgent = null, $destinationPath = null, $file = null, $followDepth = 0)
	{
		if ($followDepth > 5)
		{
			throw new Exception('Too many redirects ('.$followDepth.')');
		}

		$contentLength = 0;
		$fileLength = 0;

		if($method == 'socket')
		{
			// initialization
			$url = @parse_url($aUrl);
			if($url === false || !isset($url['scheme']))
			{
				throw new Exception('Malformed URL: '.$aUrl);
			}

			if($url['scheme'] != 'http')
			{
				throw new Exception('Invalid protocol/scheme: '.$url['scheme']);
			}
			$host = $url['host'];
			$port = isset($url['port)']) ? $url['port'] : 80;
			$path = isset($url['path']) ? $url['path'] : '/';
			if(isset($url['query']))
			{
				$path .= '?'.$url['query'];
			}
			$errno = null;
			$errstr = null;

			// connection attempt
			if (($fsock = @fsockopen($host, $port, $errno, $errstr, $timeout)) === false || !is_resource($fsock))
			{
				if(is_resource($file)) { @fclose($file); }
				throw new Exception("Error while connecting to: $host. Please try again later. $errstr");
			}

			// send HTTP request header
			fwrite($fsock,
				"GET $path HTTP/1.0\r\n"
				."Host: $host".($port != 80 ? ':'.$port : '')."\r\n"
				."User-Agent: Piwik/".Piwik_Version::VERSION.($userAgent ? " $userAgent" : '')."\r\n"
				.'Referer: http://'.Piwik_Common::getIpString()."/\r\n"
				."Connection: close\r\n"
				."\r\n"
			);

			$streamMetaData = array('timed_out' => false);
			@stream_set_blocking($fsock, true);
			@stream_set_timeout($fsock, $timeout);

			// process header
			$status = null;
			$expectRedirect = false;

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

				$streamMetaData = @stream_get_meta_data($fsock);
				if($streamMetaData['timed_out'])
				{
					if(is_resource($file)) { @fclose($file); }
					@fclose($fsock);
					throw new Exception('Timed out waiting for server response');
				}

				// a blank line marks the end of the server response header
				if(rtrim($line, "\r\n") == '')
				{
					break;
				}

				// parse first line of server response header
				if(!$status)
				{
					// expect first line to be HTTP response status line, e.g., HTTP/1.1 200 OK
					if(!preg_match('~^HTTP/(\d\.\d)\s+(\d+)(\s*.*)?~', $line, $m))
					{
						if(is_resource($file)) { @fclose($file); }
						@fclose($fsock);
						throw new Exception('Expected server response code.  Got '.rtrim($line, "\r\n"));
					}

					$status = (integer) $m[2];

					// Informational 1xx or Client Error 4xx
					if ($status < 200 || $status >= 400)
					{
						if(is_resource($file)) { @fclose($file); }
						@fclose($fsock);
						return false;
					}

					continue;
				}

				// handle redirect
				if(preg_match('/^Location:\s*(.+)/', rtrim($line, "\r\n"), $m))
				{
					if(is_resource($file)) { @fclose($file); }
					@fclose($fsock);
					// Successful 2xx vs Redirect 3xx
					if($status < 300)
					{
						throw new Exception('Unexpected redirect to Location: '.rtrim($line).' for status code '.$status);
					}
					return self::sendHttpRequestBy($method, trim($m[1]), $timeout, $userAgent, $pathDestination, $file, $followDepth+1);
				}

				// save expected content length for later verification
				if(preg_match('/^Content-Length:\s*(\d+)/', $line, $m))
				{
					$contentLength = (integer) $m[1];
				}
			}

			if(feof($fsock))
			{
				throw new Exception('Unexpected end of transmission');
			}

			// process content/body
			$response = '';

			while(!feof($fsock))
			{
				$line = fread($fsock, 8192);

				$streamMetaData = @stream_get_meta_data($fsock);
				if($streamMetaData['timed_out'])
				{
					if(is_resource($file)) { @fclose($file); }
					@fclose($fsock);
					throw new Exception('Timed out waiting for server response');
				}

				$fileLength += strlen($line);

				if(is_resource($file))
				{
					// save to file
					fwrite($file, $line);
				}
				else
				{
					// concatenate to response string
					$response .= $line;
				}
			}

			// determine success or failure
			@fclose(@$fsock);
		}
		else if($method == 'stream')
		{
			$response = false;

			// we make sure the request takes less than a few seconds to fail
			// we create a stream_context (works in php >= 5.2.1)
			// we also set the socket_timeout (for php < 5.2.1)
			$default_socket_timeout = @ini_get('default_socket_timeout');
			@ini_set('default_socket_timeout', $timeout);

			$ctx = null;
			if(function_exists('stream_context_create')) {
				$stream_options = array(
					'http' => array(
						'header' => 'User-Agent: Piwik/'.Piwik_Version::VERSION.($userAgent ? " $userAgent" : '')."\r\n"
						           .'Referer: http://'.Piwik_Common::getIpString()."/\r\n",
						'max_redirects' => 5, // PHP 5.1.0
						'timeout' => $timeout, // PHP 5.2.1
					)
				);
				$ctx = stream_context_create($stream_options);
			}

			$response = @file_get_contents($aUrl, 0, $ctx);
			$fileLength = strlen($response);

			if(is_resource($file))
			{
				// save to file
				fwrite($file, $response);
			}

			// restore the socket_timeout value
			if(!empty($default_socket_timeout))
			{
				@ini_set('default_socket_timeout', $default_socket_timeout);
			}
		}
		else if($method == 'curl')
		{
			$ch = @curl_init();

			$curl_options = array(
				CURLOPT_URL => $aUrl,
				CURLOPT_HEADER => false,
				CURLOPT_CONNECTTIMEOUT => $timeout,
				CURLOPT_BINARYTRANSFER => is_resource($file),
				CURLOPT_FOLLOWLOCATION => true,
				CURLOPT_MAXREDIRS => 5,
				CURLOPT_USERAGENT => 'Piwik/'.Piwik_Version::VERSION.($userAgent ? " $userAgent" : ''),
				CURLOPT_REFERER => 'http://'.Piwik_Common::getIpString(),
			);
			@curl_setopt_array($ch, $curl_options);

			if(is_resource($file))
			{
				@curl_setopt($ch, CURLOPT_FILE, $file);
			}
			else
			{
				@curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
			}

			ob_start();
			$response = @curl_exec($ch);
			ob_end_clean();

			if($response === true)
			{
				$response = '';
			}
			else if($response === false)
			{
				$errstr = curl_error($ch);
				if($errstr != '')
				{
					throw new Exception('curl_exec: '.$errstr);
				}
				$response = '';
			}

			$contentLength = curl_getinfo($ch, CURLINFO_CONTENT_LENGTH_DOWNLOAD);
			$fileLength = is_resource($file) ? curl_getinfo($ch, CURLINFO_SIZE_DOWNLOAD) : strlen($response);

			@curl_close($ch);
			unset($ch);
		}
		else
		{
			throw new Exception('Invalid request method: '.$method);
		}

		if(is_resource($file))
		{
			fflush($file);
			@fclose($file);

			$fileSize = filesize($destinationPath);
			if((($contentLength > 0) && ($fileLength != $contentLength)) || ($fileSize != $fileLength))
			{
				throw new Exception('File size error: '.$destinationPath.'; expected '.$contentLength.' bytes; received '.$fileLength.' bytes; saved '.$fileSize.' bytes to file');
			}
			return true;
		}

		if(($contentLength > 0) && ($fileLength != $contentLength))
		{
			throw new Exception('Content length error: expected '.$contentLength.' bytes; received '.$fileLength.' bytes');
		}
		return trim($response);
	}

	/**
	 * Fetch the file at $url in the destination $pathDestination
	 * @param string $url
	 * @param string $pathDestination
	 * @param int $tries
	 * @return true on success, throws Exception on failure
	 */
	static public function fetchRemoteFile($url, $pathDestination, $tries = 0)
	{
		@ignore_user_abort(true);
		Piwik::setMaxExecutionTime(0);
		return self::sendHttpRequest($url, 10, 'Update', $pathDestination, $tries);
	}
}