2016-06-24 17:26 GMT+02:00 Vacelet, Manuel <manuel.vace...@enalean.com>:
> > > On Sun, Jun 19, 2016 at 3:17 PM, Luca Toscano <toscano.l...@gmail.com> > wrote: > >> >> >> 2016-06-08 16:14 GMT+02:00 Vacelet, Manuel <manuel.vace...@enalean.com>: >> >>> On Tue, Jun 7, 2016 at 11:02 PM, Luca Toscano <toscano.l...@gmail.com> >>> wrote: >>> >>>> >>>> >>>> 2016-06-07 10:55 GMT+02:00 Vacelet, Manuel <manuel.vace...@enalean.com> >>>> : >>>> >>>>> >>>>> >>>>> On Mon, Jun 6, 2016 at 5:32 PM, Vacelet, Manuel < >>>>> manuel.vace...@enalean.com> wrote: >>>>> >>>>>> dOn Mon, Jun 6, 2016 at 5:00 PM, Vacelet, Manuel < >>>>>> manuel.vace...@enalean.com> wrote: >>>>>> >>>>>>> On Mon, Jun 6, 2016 at 4:09 PM, Luca Toscano <toscano.l...@gmail.com >>>>>>> > 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 header >>>>> >>>>> What do you think ? >>>>> >>>> >>>> >>>> From my tests the following snippet of code should be responsible for >>>> the switch from 'foo' to unix epoch: >>>> >>>> *https://github.com/apache/httpd/blob/2.4.x/server/util_script.c#L663 >>>> <https://github.com/apache/httpd/blob/2.4.x/server/util_script.c#L663>* >>>> >>>> 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: >>>> >>>> https://github.com/apache/httpd/blob/2.4.x/include/util_script.h#L200 >>>> >>>> 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-2 >>>> >>>> >>> Wow, 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 >> >> > Cool :) > > >> 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? >> > > I wrote a test case in the "time" branch: > https://github.com/vaceletm/bug-httpd24/tree/time > > In my own tests, I get: > --------------------->8--------------------- > < Date: Fri, 24 Jun 2016 15:21:46 GMT > < Server: Apache/2.4.18 (Red Hat) > < X-Powered-By: PHP/5.6.5 > < Last-Modified: Fri, 24 Jun 2016 15:21:48 GMT > < Transfer-Encoding: chunked > < Content-Type: text/html; charset=UTF-8 > < > { [data not shown] > 0 44 0 44 0 0 21 0 --:--:-- 0:00:02 --:--:-- > 21* Connection #0 to host localhost left intact > > * Closing connection #0 > sent value: Fri, 24 Jun 2016 17:21:46 +0200 > --------------------->8--------------------- > > The value sent doesn't respect RFC1123 (+0200 instead of GMT as time zone) > but the result is weird as you can see: > - I sent "Fri, 24 Jun 2016 17:21:46 +0200" > - but apache decided to send "Fri, 24 Jun 2016 15:21:48 GMT" > > Notice the 2 seconds ? > I put a "sleep(2)" in my php script... > > I don't know if your fix also take this into account > Thanks a lot for the precise test! The same code snippet that I modified is responsible for the behavior that you mentioned. Httpd modifies the Last-Modified header with the request's modification time if the value sent from FCGI appears to be in the future (since the HTTP RFC states "An origin server with a clock MUST NOT send a Last-Modified date that is later than the server's time of message origination (Date)."). I modified your PHP code snippet (http://apaste.info/EEz) trying to compare a GMT date vs a "Europe/Paris" one, already formatted for RFC1123, and PHP seems to agree with httpd in recognizing the "Europe/Paris" date as more recent. Moreover, if you generate a GMT date and format it for RFC1123 the header is not modified with the extra two seconds. So from what I can see httpd does the correct thing, I don't see a bug like in the previous case. What do you think? I am far from a PHP expert so I might have missed something important :) Luca
