general/5908: IE 5 hangs on a request or returns with an error -- caused by a incomplete request header

[Andras Kemeny <an...@izone.hu>]

>Number:         5908
>Category:       general
>Synopsis:       IE 5 hangs on a request or returns with an error -- caused by a incomplete request header
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    apache
>State:          open
>Class:          sw-bug
>Submitter-Id:   apache
>Arrival-Date:   Tue Mar 21 02:50:00 PST 2000
>Closed-Date:
>Last-Modified:
>Originator:     andras@izone.hu
>Release:        1.3.9 with minimal patch
>Organization:
apache
>Environment:
server: Linux 2.2.14, running Apache 1.3.9 with a minor fix to enable Script GET statements to work on GETs without queries, too. (mod_actions, one line patched)
client: Windows 98, behind an IPMASQ (Linux) firewall, running an Internet Explorer 5 (5.00.2314.build 1003), reporting itself as "MSIE 5.0; Windows 98; DigExt" as the browser
>Description:
The site where the problem occurs is a red hat 6.0 system with security patches, also using the SafeTP package (for safe FTP control connections), apart from this is nothing special. It runs Apache 1.3.9 with a minor fix to enable me to run all requests via a special CGI. The server config has been trimmed to accomodate only the most essential settings and services. The timeouts are set a bit higher than the usual to accomodate slow clients.

This problem seems to affect only our Win98 machines with this particular IE version (5.00.2314.1003), other clients work fine. This IE submits "MSIE 5.0; Windows 98; DigExt;" as the browser information. All other IE browsers tested here send "MSIE 5.0; Win32;" instead.

The problem manifests itself with either two of the following:
- the client hangs, the server-status displays a R (reading request), the particular line shows no information of the request apart from the increasing SS and "reading request...". If you are patient enough, it times out after a while and logs the following message in error_log:
[Mon Mar 20 21:53:16 2000] [error] [client 195.38.101.9] request failed: error reading the headers
- or the request immediately fails, with various reasons, both caused by a very visible error: an incomplete header is received. It is logged with many different errors, to name a few:
[Tue Mar 21 11:25:23 2000] [error] [client 195.38.101.9] File does not exist: /h
ome/httpd/html/Spo (in this case, the Name Virtual Server did not recognize the correct VHost and also, the path was incomplete (should have ended with /Sport/)
[Tue Mar 21 11:25:24 2000] [error] [client 195.38.101.9] File does not exist: /h
ome/httpd/html/spcoimages/ (in this case the request didn't contain the server identification)
[Tue Mar 21 11:46:45 2000] [error] [client 195.38.101.9] Invalid method in reque
st
Sometimes it also manifests like this (this is a browser output):
=================================
ad Request
Your browser sent a request that this server could not understand.
Request header field is missing colon separator.


Accept-Enc


-------------------------------------------------------------------------------

Apache/1.3.9 Server at courage.centrumonline.hu Port 80
=================================

When checking the connection status (netstat-wise), I see most connections only in the TIME_WAIT state, whereas hanging connections like the above have ESTABLISHED state.

I have tried setting up BrowserMatch restrictions but to no avail is it is evident that the request header doesn't arrive either in its entirety (that's when the server hangs) or only partially (error messages).

I repeat, this error occurs only with that particular IE 5 version. It is the one included in the MSDN pack with Office 2000. And this problem occurs only under Win98, the same version of IE runs without a glitch on an NT. The culprit version runs flawlessly with other servers, though.

The occurence of this problem is random (it does not make a particular distinction between VHosts or any files -- it may die on any of them), but is very persistent -- every 5th or 6th download fails.

Any ideas what is wrong?

>How-To-Repeat:
Use Internet Explorer 5.00.2314.1003 under Windows 98, and check http://www.centrumonline.hu/Sport/ for example, and reload many times.
>Fix:
Not yet. I guess one should take a look around the reception of a request header, and see if there may be a chance of premature closing.
>Release-Note:
>Audit-Trail:
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