2016-06-08 16:14 GMT+02:00 Vacelet, Manuel <manuel.vacelet@xxxxxxxxxxx>:On Tue, Jun 7, 2016 at 11:02 PM, Luca Toscano <toscano.luca@xxxxxxxxx> wrote:2016-06-07 10:55 GMT+02:00 Vacelet, Manuel <manuel.vacelet@xxxxxxxxxxx>:On Mon, Jun 6, 2016 at 5:32 PM, Vacelet, Manuel <manuel.vacelet@xxxxxxxxxxx> wrote:dOn Mon, Jun 6, 2016 at 5:00 PM, Vacelet, Manuel <manuel.vacelet@xxxxxxxxxxx> wrote:On Mon, Jun 6, 2016 at 4:09 PM, Luca Toscano <toscano.luca@xxxxxxxxx> wrote:I was able to repro building httpd from 2.4.x branch and following your configuration files on github. I am almost sure that somewhere httpd sets the Last-Modified header translating "foo" to the first Jan 1970 date. I realized though that I didn't recall the real issue, since passing value not following the RFC can lead to inconsistencies, so I went back and checked the correspondence. Quoting:"Actually I wrote this snippet to highlight the behaviour (the original code sent the date in iso8601 instead of rfc1123) because it was more obvious.During my tests (this is extracted from an automated test suite), even after having converted dates to rfc1123, I continued to get some sparse errors. What I got is that the value I sent was sometimes slightly modified (a second or 2) depending on the machine load."So my understanding is that you would like to know why a Last-Modified header with a legitimate date/time set by a PHP app gets "delayed" by a couple of seconds from httpd, right?Yes for sure, this is the primary issue.However, the (undocumented) difference of behavior from one version to another (2.2 -> 2.4 and more surprisingly from between two 2.4 versions) is also in question here.Even more strange, 2.4 built for other distrib doesn't highlight the behaviour !I made another series of test and it seems to be linked to fastcgi.I took the stock apache (2.4.6 plus tons of patches) & php-fpm (5.4.16 + tons of patches) from RHEL7 and I get the exact same behaviour (headers rewritten to EPOCH)However, if I server the very same php script from mod_php (instead of fcgi) it "works" (the headers are not modified).For the record, I also have the same behaviour (headers rewritten when using php-fpm + fastcgi) on alpine linux 3.4 that ships apache2-2.4.20.So AFAICT, it doesn't seem distro specific.On the root of the problem, from my point of view:- the difference between mod_php vs. php-fpm + fcgi is understandable (even if not desired and not documented).- the fact that fcgi handler parse & rewrite headers seems to lead to inconsistencies (I'll try to build a test case for that).- however, even if the headers are wrong, I think apache default (use EPOCH) is wrong as it leads to very inconsistent behaviour (the resource will never expire). I would prefer either:-- do not touch the header-- raise a warning and discard the headerWhat do you think ?From my tests the following snippet of code should be responsible for the switch from 'foo' to unix epoch:The function that contains the code, ap_scan_script_header_err_core_ex, is wrapped by a lot of other functions eventually called by modules like mod-proxy-fcgi. A more verbose description of the function in:Not sure what would be the best thing to do, but probably we could follow up in a official apache bugzilla task? https://bz.apache.org/bugzilla/enter_bug.cgi?product=Apache%20httpd-2Wow, thanks for the investigation !Sorry for the delay! I submitted a patch for trunk with a possible fix, namely dropping (and logging at trace1 level) any non compliant date/time set in a Last-Modified header returned by a FCGI/CGI script: http://svn.apache.org/r1748379
The fix is also in the list of proposal for backport to the 2.4.x branch, we'll see what other people think about this solution.We should also do a follow up for the other main issue, namely the fact that you see a different/delayed Last-Modified header sometimes among your FCGI/httpd responses. Can you give me an example of Last-Modified header value before/after the "delay" and a way to repro it?
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