Saturday, October 31, 2009

X-Pad: avoid browser bug

If you're looking for an explanation to this "X-Pad: avoid browser bug" header you should feel lucky. The X-Pad header is a work around Apache uses for a bug in really old versions of Netscape and it only shows up if there's a chance the 256th or 257th byte of a response is a newline.

It's a junk header, all it does is prevent the 256th and 257th byte of the response from being a newline. If Apache didn't do this, old versions of Netscape would hang.

It's a wonder why this is still part of Apache, we're talking really old versions of Netscape here.


sachin kaushik said...

Please explain regarding this in details...Still having problem to understand what its actually means?

What said...

How could he possibly explain this any clearer???

Anonymous said...

@1: -sigh- If a certain character appears at a certain location in the response the web server sends back to the browser, old versions of Netscape will not work correctly. Apache inserts that header to prevent that from ever occurring.

Is that any better?

@OP: Thank you. Was curious about that.

Urgentissimo! said...

Late 2012 and the X-Pad is still there in our network traffic (let's hope Apple does not sue for patent violation of its "-pads").