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Re: Error during 'svn export' over http with serf 1.3.1

From: Johan Corveleyn <jcorvel_at_gmail.com>
Date: Sun, 25 Aug 2013 01:36:49 +0200

On Sun, Aug 25, 2013 at 1:25 AM, Lieven Govaerts
<lieven.govaerts_at_gmail.com> wrote:
> Summarising our investigation:
> 1. The error that Johan receives is caused by the body of a 501 Method
> Not Implemented response (see [1]) being directly appended to a
> response to a GET request.
> 2. The request that triggered this response is this: DAV:
> http://subversion.tigris.org/xmlns/dav/svn/log-revprops
> So apache thinks the request method is "DAV:" and returns the error.
> It's not clear to me why apache doesn't send a status line but just
> the html body of the 501 response, but that's not really the cause of
> this particular issue.
>
> 3. The "DAV: http://subversion.tigris.org/xmlns/dav/svn/log-revprops"
> request is actually a header of a request.
> In the pcap file provided by Johan we see the following request:
> [
> GET /repos/asf/!svn/rvr/1516638/subversion/tags/1.8.3/subversion/tests/cmdline/upgrade_tests_data/upgrade_absent.tar.bz2
> HTTP/1.1
> Host: svn.apache.org
> User-Agent: SVN/1.9.0-dev (x86-microsoft-windows) serf/1.3.1
> DAV: http://subversion.tigris.org/xmlns/dav/svn/depth
>
> DAV: http://subversion.tigris.org/xmlns/dav/svn/log-revprops
> ]
>
> There is a header missing between .../depth and .../log-revprops,
> other similar requests have there the header: "DAV:
> http://subversion.tigris.org/xmlns/dav/svn/mergeinfo". There is a
> spurious CRLF where the ../mergeinfo header should be.
>
> Apache will assume based on the lack of Content-Length or chunked
> encoding header that the body of this request is empty, so will
> interpret the CRLF from the missing header as the end of the request.
> The line "DAV: http://subversion.tigris.org/xmlns/dav/svn/log-revprops"
> will then be considered the request line of the next request.
>
> 4. The question now is (and remains) why that header is missing and
> replaced by CRLF.
> Strangely enough, the serf 1.3.1 debug log shows that serf actually
> wrote that header to the socket layer, yet in the pcap file it's
> missing.
> I don't exclude an error in serf's logging yet, but the code (in
> socket_writev) looks alright to me.
>
> Not sure what that means, anti virus modifying packet data maybe?
>
> Lieven
>
> [1]
> <!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML 2.0//EN">
> <html><head>
> <title>501 Method Not Implemented</title>
> </head><body>
> <h1>Method Not Implemented</h1>
> <p>DAV: to /xmlns/dav/svn/log-revprops not supported.<br />
> </p>
> <hr>
> <address>Apache/2.2.25 (Unix) DAV/2 mod_wsgi/3.1 Python/2.7.2
> SVN/1.8.1 mod_ssl/2.2.25 OpenSSL/1.0.1e Server at
> subversion.tigris.org Port 80</address>
> </body></html>
>
> On Fri, Aug 23, 2013 at 11:51 PM, Johan Corveleyn <jcorvel_at_gmail.com> wrote:
>> I get an error when exporting
>> http://svn.apache.org/repos/asf/subversion/tags/1.8.3, with trunk@now
>> + serf 1.3.1:
>>
>> [[[
>> svn export -q http://svn.apache.org/repos/asf/subversion/tags/1.8.3
>> ..\..\..\subversion\svn\export-cmd.c:127,
>> ..\..\..\subversion\libsvn_client\export.c:1441,
>> ..\..\..\subversion\libsvn_client\export.c:1334,
>> ..\..\..\subversion\libsvn_ra_serf\update.c:2978,
>> ..\..\..\subversion\libsvn_ra_serf\util.c:2186,
>> ..\..\..\subversion\libsvn_ra_serf\util.c:2167,
>> ..\..\..\subversion\libsvn_ra_serf\update.c:1147: (apr_err=120104)
>> svn: E120104: ra_serf: An error occurred during decompression
>> ]]]
>>
>> It doesn't happen always, but say 8 times out of 10 (in different
>> places during the export).
>>
>> I haven't been able to reproduce it with serf 1.2.1, nor with serf
>> 1.3.1 via https. Only with serf 1.3.1 exporting from http.

And apparently I was mistaken here: it does occur also with serf 1.2.1
(and 1.3.0). I just didn't try long enough with 1.2.1 before (and it
does seem to happen more rarely, but that might be subjective /
randomness).

-- 
Johan
Received on 2013-08-25 01:37:41 CEST

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