I have a simple, yet critical question (critical for my application)

I will have a file url as:

```
http://a.com/b.jpg
http://a.com/b.zip
http://a.com/b.mp3
<or any valid file>

```

When user will click on download link for any specific file (say b.jpg) on my site i.e., b.com, user will see url as

```
http://b.com/?f=1

```

I don't want user to see original URL and secondly, want to force download of file, irrespective of filetype

I know that I can achieve this using readfile (Check Example1 at <http://php.net/manual/en/function.readfile.php>), but I don't know filesize and mimetype, how can I get assurance that file will be downloaded properly?

Please help guys