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Dealing with bad server chunking

From: Adrien W. de Croy <adrien@qbik.com>
Date: Fri, 15 Mar 2013 04:44:30 +0000
To: "IETF HTTP Working Group" <ietf-http-wg@w3.org>
Message-Id: <emd2935d83-5cfa-4f4a-88d0-a3baee56508e@bombed>
Hi all

we have recently had issues with a site where the server sends chunked 
responses back but closes the TCP connection prior to sending any 0 
chunk (in fact we never see a packet with this).

WinGate detects this as an abortive close, and if there were any filters 
processing the stream, they are reset, and the data may not go to the 

However, client browsers typically "forgive" this transgression without 
any sort of warning.  Should we be making more forceful suggestions 
about this in the specs?

It seems slightly dangerous that a browser would consider content 
perfectly fine to use when the chunked transfer was aborted.

Is this actually a security issue, or should we be more tolerant?  The 
customer of course just wants to be able to go to the page, and chances 
of getting it fixed seem slim.   Is this also a known bug in IIS6.0?



GET / HTTP/1.1
Host: www.smemsc.org
Cache-Control: no-cache
Pragma: no-cache
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.22 
(KHTML, like Gecko) Chrome/25.0.1364.97 Safari/537.22
Accept-Encoding: gzip,deflate,sdch
Accept-Language: en-US,en;q=0.8
Accept-Charset: ISO-8859-1,utf-8;q=0.7,*;q=0.3
Connection: Keep-Alive

HTTP/1.1 200 OK
Connection: close
Date: Fri, 15 Mar 2013 04:29:44 GMT
Server: Microsoft-IIS/6.0
x-server: sjl03
X-AspNet-Version: 2.0.50727
Transfer-Encoding: chunked
Cache-Control: private
Content-Type: text/html; charset=utf-8

<!-- Redirection Services SJL01WRED03 H1 -->
<frameset rows='100%, *' frameborder=no framespacing=0 border=0>
<frame src="http://www.smemsc.comcastbiz.net" name=mainwindow 
frameborder=no framespacing=0 marginheight=0 marginwidth=0></frame>
<h2>Your browser does not support frames.  We recommend upgrading your 
<center>Click <a href="herehttp://www.smemsc.comcastbiz.net">here</a> to 
enter the site.</center>
Received on Friday, 15 March 2013 04:45:00 UTC

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