Is content length necessary on inline? - php

Question

I am asking this because my requests keep getting "Content Length Mismatch" on files larger than 4Mb even though the content length and the file size is exact match. If I remove the Content Length header, everything works fine.
Is there an advantage or necessity of using Content Length in the headers for inline content (not attachment)?
[EDIT] Code:
public function actionViewFile($id) {
$model = File::model()->findByPk($id);
if(!$model) {
throw new CHttpException(404, "File not found");
}
$data = file_get_contents($this->storageDir.'/'.$model->fileName);
header('Content-type: '.$model->mime_type);
header('Content-length: '.$model->size); //I have tried calling `mb_strlen($data);`
echo $data;
Yii::app()->end(); //I have tried calling `die;`
}
The framework I am using is Yii, which doesn't really matter for the context of this problem.

Answer 1

The Content-Length entity-header field indicates the size of the entity-body, in decimal number of OCTETs, sent to the recipient or, in the case of the HEAD method, the size of the entity-body that would have been sent had the request been a GET.
Try using filesize() as per the following:
public function actionViewFile($id) {
$model = File::model()->findByPk($id);
if(!$model) {
throw new CHttpException(404, "File not found");
}
$filepath= $this->storageDir.'/'.$model->fileName;
$data = file_get_contents($filepath);
header('Content-type: '.$model->mime_type);
header("Cache-Control: no-cache, must-revalidate");
header('Content-Length: ' . sprintf('%u', filesize($filepath)))
echo $data;
return Yii::app()->end(); //I have tried calling `die;`
}