|Summary:||flush buckets followed by eos bucket emit multiple last-chunks|
|Product:||Apache httpd-2||Reporter:||Alan Krueger <Alan_Krueger>|
|Component:||Core||Assignee:||Apache HTTPD Bugs Mailing List <bugs>|
Description Alan Krueger 2004-01-26 21:52:42 UTC
When an HTTP/1.1 connection to an ISAPI extension uses Keep-Alive and the output is written in Chunked Transfer-Encoding, multiple last-chunk markers (http://www.w3.org/Protocols/rfc2616/rfc2616-sec3.html#sec3.6.1) appear in the response. This appears to be due to the isapi_handler appending both a flush bucket and an eos bucket on the brigade. Another follows that, created by end_output_stream. Since the eos bucket appears to drive the last-chunk marker, two are output in the response. The symptoms for this vary by User-Agent, but in my situation the ISAPI extension is returning XML, where the extra last-chunk appears to be more noticeable. Specifically, MSIE on Win2k and Mozilla on RH9 sometimes display the XML properly, other times they display the chunked response verbatim including previous leading last-chunk and the following response header as part of the response. (MSIE actually just displays a 0 in those cases.)
Comment 1 Robert Olofsson 2005-01-08 20:12:40 UTC
I have seen multiple last-chunks from other web servers, not sure if it the same problem. This came from a php-page. Multiple last-chunks causes my web proxy, rabbit, to read the extra last chunk as the next http header in the keepalive stream. This results in broken images. If I do not use a proxy mozilla seems to silently remove the extra last-chunk. I have a ethereal trace when this happens if anyone wants it. Seems to happen often, but non-deterministacally on http://www.eet.gr/
Comment 2 William A. Rowe Jr. 2006-06-22 07:20:09 UTC
Reclassified this because it's not always going to be possible for a module author to know that a flush is ending the entire stream, depending on the protocol they are trying to implement. The eos bucket handler is gonna have to get a brain on this point, or else the flush bucket handler is gonna have to learn not to flush nothing. Either way the flaw is probably in the chunk protocol filter itself.
Comment 3 William A. Rowe Jr. 2006-06-22 07:26:36 UTC
Whoops, off to core with this.
Comment 4 Ruediger Pluem 2006-06-22 21:27:20 UTC
From my point of view this problem is independant of the flush bucket. I guess we see this problem if pass the eos bucket twice thru the chunk filter in different invocations (=> and in different brigades). I guess the possible approach to solve this in the chunk filter is to remove the chunk filter from the filter chain once we see an eos bucket in the chunk filter.
Comment 5 Joe Orton 2010-01-31 06:10:30 UTC
Why is this not simply a bug in whatever handler generated multiple EOS buckets?
Comment 6 William A. Rowe Jr. 2018-11-07 21:08:32 UTC
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