Mercurial > hg > nginx
annotate docs/html/50x.html @ 9300:5be23505292b default tip
SSI: fixed incorrect or duplicate stub output.
Following 3518:eb3aaf8bd2a9 (0.8.37), r->request_output is only set
if there are data in the first buffer sent in the subrequest. As a
result, following the change mentioned this flag cannot be used to
prevent duplicate ngx_http_ssi_stub_output() calls, since it is not
set if there was already some output, but the first buffer was empty.
Still, when there are multiple subrequests, even an empty subrequest
response might be delayed by the postpone filter, leading to a second
call of ngx_http_ssi_stub_output() during finalization from
ngx_http_writer() the subreqest buffers are released by the postpone
filter. Since r->request_output is not set after the first call, this
resulted in duplicate stub output.
Additionally, checking only the first buffer might be wrong in some
unusual cases. For example, the first buffer might be empty if
$r->flush() is called before printing any data in the embedded Perl
module.
Depending on the postpone_output value and corresponding sizes, this
issue can result in either duplicate or unexpected stub output, or
"zero size buf in writer" alerts.
Following 8124:f5515e727656 (1.23.4), it became slightly easier to
reproduce the issue, as empty static files and empty cache items now
result in a response with an empty buffer. Before the change, an empty
proxied response can be used to reproduce the issue.
Fix is check all buffers and set r->request_output if any non-empty
buffers are sent. This ensures that all unusual cases of non-empty
responses are covered, and also that r->request_output will be set
after the first stub output, preventing duplicate output.
Reported by Jan Gassen.
author | Maxim Dounin <mdounin@mdounin.ru> |
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date | Thu, 04 Jul 2024 17:41:28 +0300 |
parents | f2ddd0c491bf |
children |
rev | line source |
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4840
b5ba6f22a0fc
Improved 50x error page.
Valentin Bartenev <vbart@nginx.com>
parents:
663
diff
changeset
|
1 <!DOCTYPE html> |
657 | 2 <html> |
3 <head> | |
4840
b5ba6f22a0fc
Improved 50x error page.
Valentin Bartenev <vbart@nginx.com>
parents:
663
diff
changeset
|
4 <title>Error</title> |
657 | 5 <style> |
7903
f2ddd0c491bf
Dark mode support in welcome and 50x error pages.
Maxim Dounin <mdounin@mdounin.ru>
parents:
7902
diff
changeset
|
6 html { color-scheme: light dark; } |
7902
67c68cd973b8
Welcome and 50x error pages style.
Maxim Dounin <mdounin@mdounin.ru>
parents:
7336
diff
changeset
|
7 body { width: 35em; margin: 0 auto; |
67c68cd973b8
Welcome and 50x error pages style.
Maxim Dounin <mdounin@mdounin.ru>
parents:
7336
diff
changeset
|
8 font-family: Tahoma, Verdana, Arial, sans-serif; } |
657 | 9 </style> |
10 </head> | |
4840
b5ba6f22a0fc
Improved 50x error page.
Valentin Bartenev <vbart@nginx.com>
parents:
663
diff
changeset
|
11 <body> |
b5ba6f22a0fc
Improved 50x error page.
Valentin Bartenev <vbart@nginx.com>
parents:
663
diff
changeset
|
12 <h1>An error occurred.</h1> |
b5ba6f22a0fc
Improved 50x error page.
Valentin Bartenev <vbart@nginx.com>
parents:
663
diff
changeset
|
13 <p>Sorry, the page you are looking for is currently unavailable.<br/> |
b5ba6f22a0fc
Improved 50x error page.
Valentin Bartenev <vbart@nginx.com>
parents:
663
diff
changeset
|
14 Please try again later.</p> |
b5ba6f22a0fc
Improved 50x error page.
Valentin Bartenev <vbart@nginx.com>
parents:
663
diff
changeset
|
15 <p>If you are the system administrator of this resource then you should check |
7336
1cd63ae46243
A link to the error_log directive on nginx.org removed.
Maxim Konovalov <maxim@nginx.com>
parents:
4840
diff
changeset
|
16 the error log for details.</p> |
4840
b5ba6f22a0fc
Improved 50x error page.
Valentin Bartenev <vbart@nginx.com>
parents:
663
diff
changeset
|
17 <p><em>Faithfully yours, nginx.</em></p> |
657 | 18 </body> |
19 </html> |