Firebug 1.7 moving headers to raw POST source

Edit : The issue discussed here has been fixed in Firebug 1.9a2

It took me a whole day to track this bug down. At first I thought something was wrong in my request, I tried to replay it using Firebug and I kept hitting a "malformed request" error.

Debugging it in reverse order, using Wireshark and other tools I finally came to the conclusion that my request was indeed valid.

So what ?

The guilty part was indeed Firebug. When I ran a simple POST request from Flash, and inspect it from Firebug, I could spot that no Content-Length nor Content-Type headers were displayed in the "Headers" part. I then saw that the "source" part of the POSTtab contains my missing headers. What was that ?

HTTP POST Request are supposed to be split into two parts. First part are the headers, each separated by a \r\n. Then, after and empty line was the POST raw content. Seeing that my headers gets mixed up with the POSTdata I thought that the request was malformed and a \r\n was added too early.

I checked with Wireshark and with PHP on the back end, and no, the request was indeed absolutly valid. Wireshark did not show any \r\n that shouldn't be there and PHP correctly parsed my request. The only issue was the details displayed by Firebug.

So it's a display bug ? I can live with it.

Well, actually, it's a little more than just a display bug. It kind of blocks my usual debugging workflow.

To debug an XHR request, I don't usually restart the whole page request just to debug one of the inner request.

The Firebug ability to "open request in new tab" is a time saver for me. I can play and replay the same request over and over until it's debuggued.

But with this bug, I can't use this feature. Opening the request in new tab will not send the slipped headers, and will instead send them in the POST source, resulting in a corrupted posted data.

I've posted an issue on the Firebug bug tracker. I hope it will get resolved soon. Until then, I'm using Live HTTP Headers to capture and replay the requests I need to debug.


Seems like the bug come from Firefox internals and not Firebug. More details on this post.

Edit : Seems to be resolved in Firefox, will be available in next release (8.0 I guess).

Tags : #live-http-headers #flash #php #bug #firebug #post

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