How to obtain size of served HTTP response in PHP

Question

In a PHP shutdown function, I want to know the size of the HTTP response that's been received by the client.

I'd like to register a shutdown function and verify the size of the HTTP response received by the client with the size of the file which was read. This would let me flag cases where the response was incomplete.

Background: We're seeing reports of damaged (incomplete) file downloads using Ubercart uc_file.

http://api.ubercart.org/api/function/_uc_file_download_transfer/2 is the function serving the file. It already checks that the complete file has been read before logging the download, but it doesn't check if the client was still connected when the file is fully served.

Answer 1

I don't know how to obtain the size of generated content, but the reason why your clients are experiencing incomplete downloads could be that you don't specify the correct Content-Length header before sending the file. Standards-compliant browsers will not save the file if it's size turns out to be less than the Content-Length declared in HTTP response.