I have an issue with my squid on the website : <http://www.draw.io>
I have one schema and I am not able to export it as a PNG (I got a white page on the web browser like the website didn't answer.)

Without using squid export is working fine.

I look at the logs and here is what I found :
When not working I got :
1376985774.106 0 127.0.0.1 TCP\_DENIED/407 4366 POST <http://exp.draw.io/ImageExport2/export> - NONE/- text/html

When I delete some stuff on my design it works :

TCP\_MISS/200 76269 POST <http://exp.draw.io/ImageExport2/export> hugo
@domain.LOCAL DIRECT/199.38.86.62 application/x-unknown

For me it seems related to the post size. Should I modify something in my squid configuration ? (which is pretty basic).