Previously nginx used to mark backend again as live as soon as fail_timeout
passes (10s by default) since last failure. On the other hand, detecting
dead backend takes up to 60s (proxy_connect_timeout) in typical situation
"backend is down and doesn't respond to any packets". This resulted in
suboptimal behaviour in the above situation (up to 23% of requests were
directed to dead backend with default settings).
More detailed description of the problem may be found here (in Russian):
http://mailman.nginx.org/pipermail/nginx-ru/2011-August/042172.html
Fix is to only allow one request after fail_timeout passes, and
mark backend as "live" only if this request succeeds.
Note that with new code backend will not be marked "live" unless "check"
request is completed, and this may take a while in some specific workloads
(e.g. streaming). This is believed to be acceptable.
Second aio post happened when timer set by limit_rate expired while we have
aio request in flight, resulting in "second aio post" alert and socket leak.
The patch adds actual protection from aio calls with r->aio already set to
aio sendfile code in ngx_http_copy_filter(). This should fix other cases
as well, e.g. when sending buffered to disk upstream replies while still
talking to upstream.
The ngx_http_writer() is also fixed to handle the above case (though it's
mostly optimization now).
Reported by Oleksandr V. Typlyns'kyi.
For files with '?' in their names autoindex generated links with '?' not
escaped. This resulted in effectively truncated links as '?' indicates
query string start.
This is an updated version of the patch originally posted at [1]. It
introduces generic NGX_ESCAPE_URI_COMPONENT which escapes everything but
unreserved characters as per RFC 3986. This approach also renders unneeded
special colon processing (as colon is percent-encoded now), it's dropped
accordingly.
[1] http://nginx.org/pipermail/nginx-devel/2010-February/000112.html
Reported by Konstantin Leonov.
If cache was bypassed with proxy_cache_bypass, cache-controlling headers
(Cache-Control, Expires) wasn't considered and response was cached even
if it was actually non-cacheable.
Patch by John Ferlito.
Configuration with duplicate upstream blocks defined after first use, i.e.
like
server {
...
location / {
proxy_pass http://backend;
}
}
upstream backend { ... }
upstream backend { ... }
now correctly results in "duplicate upstream" error.
Additionally, upstream blocks defined after first use now handle various
server directive parameters ("weight", "max_fails", etc.). Previously
configuration like
server {
...
location / {
proxy_pass http://backend;
}
}
upstream backend {
server 127.0.0.1 max_fails=5;
}
incorrectly resulted in "invalid parameter "max_fails=5"" error.
For normal cached responses ngx_http_cache_send() sends last buffer and then
request finalized via ngx_http_finalize_request() call, i.e. everything is
ok.
But for stale responses (i.e. when upstream died, but we have something in
cache) the same ngx_http_cache_send() sends last buffer, but then in
ngx_http_upstream_finalize_request() another last buffer is send. This
causes duplicate final chunk to appear if chunked encoding is used (and
resulting problems with keepalive connections and so on).
Fix this by not sending in ngx_http_upstream_finalize_request()
another last buffer if we know response was from cache.
The special case in question leads to replies without body in
configuration like
location / { error_page 404 /zero; return 404; }
location /zero { return 204; }
while replies with empty body are expected per protocol specs.
Correct one will look like
if (status == NGX_HTTP_NO_CONTENT) {
rc = ngx_http_send_header(r);
if (rc == NGX_ERROR || r->header_only) {
return rc;
}
return ngx_http_send_special(r, NGX_HTTP_LAST);
}
though it looks like it's better to drop this special case at all.
Big POST (not fully preread) to a
location / {
return 202;
}
resulted in incorrect behaviour due to "return" code path not calling
ngx_http_discard_request_body(). The same applies to all "return" used
with 2xx/3xx codes except 201 and 204, and to all "return ... text" uses.
Fix is to add ngx_http_discard_request_body() call to ngx_http_send_response()
function where it looks appropriate. Discard body call from emtpy gif module
removed as it's now redundant.
Reported by Pyry Hakulinen, see
http://mailman.nginx.org/pipermail/nginx/2011-August/028503.html
Test case:
location / {
error_page 405 /nope;
return 405;
}
location /nope {
return 200;
}
This is expected to return 405 with empty body, but in 0.8.42+ will return
builtin 405 error page as well (though not counted in Content-Length, thus
breaking protocol).
Fix is to use status provided by rewrite script execution in case
it's less than NGX_HTTP_BAD_REQUEST even if r->error_status set. This
check is in line with one in ngx_http_script_return_code().
Note that this patch also changes behaviour for "return 302 ..." and
"rewrite ... redirect" used as error handler. E.g.
location / {
error_page 405 /redirect;
return 405;
}
location /redirect {
rewrite ^ http://example.com/;
}
will actually return redirect to "http://example.com/" instead of builtin 405
error page with meaningless Location header. This looks like correct change
and it's in line with what happens on e.g. directory redirects in error
handlers.
Replies with 201 code contain body, and we should clearly indicate it's
empty if it's empty. Before 0.8.32 chunked was explicitly disabled for
201 replies and as a result empty body was indicated by connection close
(not perfect, but worked). Since 0.8.32 chunked is enabled, and this
causes incorrect responses from dav module when HTTP/1.1 is used: with
"Transfer-Encoding: chunked" but no chunks at all.
Fix is to actually return empty body in special response handler instead
of abusing r->header_only flag.
See here for initial report:
http://mailman.nginx.org/pipermail/nginx-ru/2010-October/037535.html
