support simple request ranges for direct downloads

Signed-off-by: Florian Pritz <bluewind@xinu.at>

2 files changed, 101 insertions, 10 deletions

diff --git a/application/helpers/filebin_helper.php b/application/helpers/filebin_helper.php
index 4063fd3fb..bb265d6e5 100644
--- a/application/helpers/filebin_helper.php
+++ b/application/helpers/filebin_helper.php
@@ -7,4 +7,103 @@ function format_bytes($size, $precision = 2){
 		return round(pow(1024, $base - floor($base)), $precision) . $suffixes[floor($base)];
 }
 
+// Original source: http://www.phpfreaks.com/forums/index.php?topic=198274.msg895468#msg895468
+function rangeDownload($file, $filename, $type)
+{
+	$fp = @fopen($file, 'r');
+
+	$size	= filesize($file); // File size
+	$length = $size;	   // Content length
+	$start	= 0;		   // Start byte
+	$end	= $size - 1;	   // End byte
+	// Now that we've gotten so far without errors we send the accept range header
+	/* At the moment we only support single ranges.
+	 * Multiple ranges requires some more work to ensure it works correctly
+	 * and comply with the spesifications: http://www.w3.org/Protocols/rfc2616/rfc2616-sec19.html#sec19.2
+	 *
+	 * Multirange support annouces itself with:
+	 * header('Accept-Ranges: bytes');
+	 *
+	 * Multirange content must be sent with multipart/byteranges mediatype,
+	 * (mediatype = mimetype)
+	 * as well as a boundry header to indicate the various chunks of data.
+	 */
+	header("Accept-Ranges: 0-$length");
+	// header('Accept-Ranges: bytes');
+	// multipart/byteranges
+	// http://www.w3.org/Protocols/rfc2616/rfc2616-sec19.html#sec19.2
+	if (isset($_SERVER['HTTP_RANGE']))
+	{
+		$c_start = $start;
+		$c_end	 = $end;
+		// Extract the range string
+		list(, $range) = explode('=', $_SERVER['HTTP_RANGE'], 2);
+		// Make sure the client hasn't sent us a multibyte range
+		if (strpos($range, ',') !== false)
+		{
+			// (?) Shoud this be issued here, or should the first
+			// range be used? Or should the header be ignored and
+			// we output the whole content?
+			header('HTTP/1.1 416 Requested Range Not Satisfiable');
+			header("Content-Range: bytes $start-$end/$size");
+			// (?) Echo some info to the client?
+			exit;
+		}
+		// If the range starts with an '-' we start from the beginning
+		// If not, we forward the file pointer
+		// And make sure to get the end byte if spesified
+		if ($range{0} == '-')
+		{
+			// The n-number of the last bytes is requested
+			$c_start = $size - substr($range, 1);
+		}
+		else
+		{
+			$range	= explode('-', $range);
+			$c_start = $range[0];
+			$c_end	 = (isset($range[1]) && is_numeric($range[1])) ? $range[1] : $size;
+		}
+		/* Check the range and make sure it's treated according to the specs.
+		 * http://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html
+		 */
+		// End bytes can not be larger than $end.
+		$c_end = ($c_end > $end) ? $end : $c_end;
+		// Validate the requested range and return an error if it's not correct.
+		if ($c_start > $c_end || $c_start > $size - 1 || $c_end >= $size)
+		{
+			header('HTTP/1.1 416 Requested Range Not Satisfiable');
+			header("Content-Range: bytes $start-$end/$size");
+			// (?) Echo some info to the client?
+			exit;
+		}
+		$start	= $c_start;
+		$end	= $c_end;
+		$length = $end - $start + 1; // Calculate new content length
+		fseek($fp, $start);
+		header('HTTP/1.1 206 Partial Content');
+	}
+	// Notify the client the byte range we'll be outputting
+	header("Content-Range: bytes $start-$end/$size");
+	header("Content-Length: $length");
+	header("Content-disposition: inline; filename=\"".$filename."\"\n");
+	header("Content-Type: ".$type."\n");
+
+	// Start buffered download
+	$buffer = 1024 * 8;
+	while(!feof($fp) && ($p = ftell($fp)) <= $end)
+	{
+		if ($p + $buffer > $end)
+		{
+			// In case we're only outputtin a chunk, make sure we don't
+			// read past the length
+			$buffer = $end - $p + 1;
+		}
+		set_time_limit(0); // Reset time limit for big files
+		echo fread($fp, $buffer);
+		flush(); // Free up memory. Otherwise large files will trigger PHP's memory limit.
+	}
+
+	fclose($fp);
+}
+
 # vim: set noet:
diff --git a/application/models/file_mod.php b/application/models/file_mod.php
index 54fe3d550..f13fd40b8 100644
--- a/application/models/file_mod.php
+++ b/application/models/file_mod.php
@@ -254,17 +254,9 @@ class File_mod extends CI_Model {
 		|| filesize($file) > $this->config->item('upload_max_text_size')
 		) {
 			if ($mode == 'plain') {
-				header("Content-Type: text/plain\n");
-			} else {
-				header("Content-Type: ".$type."\n");
-			}
-			header("Content-disposition: inline; filename=\"".$filedata['filename']."\"\n");
-			header("Content-Length: ".filesize($file)."\n");
-			$fp = fopen($file,"r");
-			while (!feof($fp)) {
-				echo fread($fp,4096);
+				$type = "text/plain";
 			}
-			fclose($fp);
+			rangeDownload($file, $filedata["filename"], $type);
 			exit();
 		}