Databases
StackOverflow2013
Postsdbo
POHTTP Headers for File Downloads
Body
 

Note that there are some explanatory texts on larger screens.

plurals
  1. POHTTP Headers for File Downloads
    text
    copied!<p>I've written a PHP script that handles file downloads, determining which file is being requested and setting the proper HTTP headers to trigger the browser to actually download the file (rather than displaying it in the browser).</p> <p>I now have a problem where some users have reported certain files being identified incorrectly (so regardless of extension, the browser will consider it a GIF image). I'm guessing this is because I haven't set the "Content-type" in the response header. Is this most likely the case? If so, is there a fairly generic type that could be used for all files, rather than trying to account for every possible file type?</p> <p>Currently I'm only setting the value "Content-disposition: attachment; filename=arandomf.ile"</p> <p><strong>Update:</strong> I followed this guide here to build a more robust process for file downloads (<a href="http://w-shadow.com/blog/2007/08/12/how-to-force-file-download-with-php/" rel="noreferrer">http://w-shadow.com/blog/2007/08/12/how-to-force-file-download-with-php/</a>), but there is a significant delay between when the script is executed and when the browser's download dialog appears. Can anyone identify the bottleneck that is causing this?</p> <p>Here's my implementation:</p> <pre><code>/** * Outputs the specified file to the browser. * * @param string $filePath the path to the file to output * @param string $fileName the name of the file * @param string $mimeType the type of file */ function outputFile($filePath, $fileName, $mimeType = '') { // Setup $mimeTypes = array( 'pdf' =&gt; 'application/pdf', 'txt' =&gt; 'text/plain', 'html' =&gt; 'text/html', 'exe' =&gt; 'application/octet-stream', 'zip' =&gt; 'application/zip', 'doc' =&gt; 'application/msword', 'xls' =&gt; 'application/vnd.ms-excel', 'ppt' =&gt; 'application/vnd.ms-powerpoint', 'gif' =&gt; 'image/gif', 'png' =&gt; 'image/png', 'jpeg' =&gt; 'image/jpg', 'jpg' =&gt; 'image/jpg', 'php' =&gt; 'text/plain' ); $fileSize = filesize($filePath); $fileName = rawurldecode($fileName); $fileExt = ''; // Determine MIME Type if($mimeType == '') { $fileExt = strtolower(substr(strrchr($filePath, '.'), 1)); if(array_key_exists($fileExt, $mimeTypes)) { $mimeType = $mimeTypes[$fileExt]; } else { $mimeType = 'application/force-download'; } } // Disable Output Buffering @ob_end_clean(); // IE Required if(ini_get('zlib.output_compression')) { ini_set('zlib.output_compression', 'Off'); } // Send Headers header('Content-Type: ' . $mimeType); header('Content-Disposition: attachment; filename="' . $fileName . '"'); header('Content-Transfer-Encoding: binary'); header('Accept-Ranges: bytes'); // Send Headers: Prevent Caching of File header('Cache-Control: private'); header('Pragma: private'); header('Expires: Mon, 26 Jul 1997 05:00:00 GMT'); // Multipart-Download and Download Resuming Support if(isset($_SERVER['HTTP_RANGE'])) { list($a, $range) = explode('=', $_SERVER['HTTP_RANGE'], 2); list($range) = explode(',', $range, 2); list($range, $rangeEnd) = explode('-', $range); $range = intval($range); if(!$rangeEnd) { $rangeEnd = $fileSize - 1; } else { $rangeEnd = intval($rangeEnd); } $newLength = $rangeEnd - $range + 1; // Send Headers header('HTTP/1.1 206 Partial Content'); header('Content-Length: ' . $newLength); header('Content-Range: bytes ' . $range - $rangeEnd / $size); } else { $newLength = $size; header('Content-Length: ' . $size); } // Output File $chunkSize = 1 * (1024*1024); $bytesSend = 0; if($file = fopen($filePath, 'r')) { if(isset($_SERVER['HTTP_RANGE'])) { fseek($file, $range); while(!feof($file) &amp;&amp; !connection_aborted() &amp;&amp; $bytesSend &lt; $newLength) { $buffer = fread($file, $chunkSize); echo $buffer; flush(); $bytesSend += strlen($buffer); } fclose($file); } } } </code></pre>
 

Querying!

 
Guidance
An individual column

Larger individual text columns get their own page to allow for proper reading.

SQuiL has stopped working due to an internal error.

If you are curious you may find further information in the browser console, which is accessible through the devtools (F12).

Reload