Merge branch 'ticket/bantu/9627' into develop

* ticket/bantu/9627:
  [ticket/9627] Prefix function names with 'phpbb_'.
  [ticket/9627] Adding unit tests for http_byte_range().
  [ticket/9627] Adding download unit tests.
  [ticket/9627] Split http_range_request() into several functions.
  [ticket/9627] Make sure range request reads till the end of the file.
  [ticket/9627] Make use of 'static' since the function is called more than once
  [ticket/9627] Make sure the database record for the filesize is correct.
  [ticket/9627] Do not increase download counter if file is requested partially.
  [ticket/9627] Support for HTTP range requests in download/file.php

phpBB/includes/functions_download.php

@@ -157,6 +157,16 @@ function send_file_to_browser($attachment, $upload_dir, $category)
 		trigger_error('UNABLE_TO_DELIVER_FILE');
 	}
 
+	// Make sure the database record for the filesize is correct
+	if ($size > 0 && $size != $attachment['filesize'])
+	{
+		// Update database record
+		$sql = 'UPDATE ' . ATTACHMENTS_TABLE . '
+			SET filesize = ' . (int) $size . '
+			WHERE attach_id = ' . (int) $attachment['attach_id'];
+		$db->sql_query($sql);
+	}
+
 	// Now the tricky part... let's dance
 	header('Pragma: public');
 
@@ -226,6 +236,16 @@ function send_file_to_browser($attachment, $upload_dir, $category)
 
 		if ($fp !== false)
 		{
+			// Deliver file partially if requested
+			if ($range = phpbb_http_byte_range($size))
+			{
+				fseek($fp, $range['byte_pos_start']);
+
+				send_status_line(206, 'Partial Content');
+				header('Content-Range: bytes ' . $range['byte_pos_start'] . '-' . $range['byte_pos_end'] . '/' . $range['bytes_total']);
+				header('Content-Length: ' . $range['bytes_requested']);
+			}
+
 			while (!feof($fp))
 			{
 				echo fread($fp, 8192);
@@ -407,3 +427,151 @@ function file_gc()
 	$db->sql_close();
 	exit;
 }
+
+/**
+* HTTP range support (RFC 2616 Section 14.35)
+*
+* Allows browsers to request partial file content
+* in case a download has been interrupted.
+*
+* @param int $filesize		the size of the file in bytes we are about to deliver
+*
+* @return mixed		false if the whole file has to be delivered
+*					associative array on success
+*/
+function phpbb_http_byte_range($filesize)
+{
+	// Only call find_range_request() once.
+	static $request_array;
+
+	if (!$filesize)
+	{
+		return false;
+	}
+
+	if (!isset($request_array))
+	{
+		$request_array = phpbb_find_range_request();
+	}
+	
+	return (empty($request_array)) ? false : phpbb_parse_range_request($request_array, $filesize);
+}
+
+/**
+* Searches for HTTP range request in super globals.
+*
+* @return mixed		false if no request found
+*					array of strings containing the requested ranges otherwise
+*					e.g. array(0 => '0-0', 1 => '123-125')
+*/
+function phpbb_find_range_request()
+{
+	$globals = array(
+		array('_SERVER',	'HTTP_RANGE'),
+		array('_ENV',		'HTTP_RANGE'),
+	);
+
+	foreach ($globals as $array)
+	{
+		$global	= $array[0];
+		$key	= $array[1];
+
+		// Make sure range request starts with "bytes="
+		if (isset($GLOBALS[$global][$key]) && strpos($GLOBALS[$global][$key], 'bytes=') === 0)
+		{
+			// Strip leading 'bytes='
+			// Multiple ranges can be separated by a comma
+			return explode(',', substr($GLOBALS[$global][$key], 6));
+		}
+	}
+
+	return false;
+}
+
+/**
+* Analyses a range request array.
+*
+* A range request can contain multiple ranges,
+* we however only handle the first request and
+* only support requests from a given byte to the end of the file.
+*
+* @param array	$request_array	array of strings containing the requested ranges
+* @param int	$filesize		the full size of the file in bytes that has been requested
+*
+* @return mixed		false if the whole file has to be delivered
+*					associative array on success
+*						byte_pos_start		the first byte position, can be passed to fseek()
+*						byte_pos_end		the last byte position
+*						bytes_requested		the number of bytes requested
+*						bytes_total			the full size of the file
+*/
+function phpbb_parse_range_request($request_array, $filesize)
+{
+	// Go through all ranges
+	foreach ($request_array as $range_string)
+	{
+		$range = explode('-', trim($range_string));
+
+		// "-" is invalid, "0-0" however is valid and means the very first byte.
+		if (sizeof($range) != 2 || $range[0] === '' && $range[1] === '')
+		{
+			continue;
+		}
+
+		if ($range[0] === '')
+		{
+			// Return last $range[1] bytes.
+
+			if (!$range[1])
+			{
+				continue;
+			}
+
+			if ($range[1] >= $filesize)
+			{
+				return false;
+			}
+
+			$first_byte_pos	= $filesize - (int) $range[1];
+			$last_byte_pos	= $filesize - 1;
+		}
+		else
+		{
+			// Return bytes from $range[0] to $range[1]
+
+			$first_byte_pos	= (int) $range[0];
+			$last_byte_pos	= (int) $range[1];
+
+			if ($last_byte_pos && $last_byte_pos < $first_byte_pos)
+			{
+				// The requested range contains 0 bytes.
+				continue;
+			}
+
+			if ($first_byte_pos >= $filesize)
+			{
+				// Requested range not satisfiable
+				return false;
+			}
+
+			// Adjust last-byte-pos if it is absent or greater than the content.
+			if ($range[1] === '' || $last_byte_pos >= $filesize)
+			{
+				$last_byte_pos = $filesize - 1;
+			}
+		}
+
+		// We currently do not support range requests that end before the end of the file
+		if ($last_byte_pos != $filesize - 1)
+		{
+			continue;
+		}
+
+		return array(
+			'byte_pos_start'	=> $first_byte_pos,
+			'byte_pos_end'		=> $last_byte_pos,
+			'bytes_requested'	=> $last_byte_pos - $first_byte_pos + 1,
+			'bytes_total'		=> $filesize,
+		);
+	}
+}