In OpenSSL, session resumption always happens in the default SSL context, prior to invoking the SNI callback. Further, unlike in TLSv1.2 and older protocols, SSL_get_servername() returns values received in the resumption handshake, which may be different from the value in the initial handshake. Notably, this makes the restriction added in b720f650b insufficient for sessions resumed with different SNI server name. Considering the example from b720f650b, previously, a client was able to request example.org by presenting a certificate for example.org, then to resume and request example.com. The fix is to reject handshakes resumed with a different server name, if verification of client certificates is enabled in a corresponding server configuration.
The directive sets a timeout during which a keepalive connection will not be closed by nginx for connection reuse or graceful shutdown. The change allows clients that send multiple requests over the same connection without delay or with a small delay between them, to avoid receiving a TCP RST in response to one of them. This excludes network issues and non-graceful shutdown. As a side-effect, it also addresses the TCP reset problem described in RFC 9112, Section 9.6, when the last sent HTTP response could be damaged by a followup TCP RST. It is important for non-idempotent requests, which cannot be retried by client. It is not recommended to set keepalive_min_timeout to large values as this can introduce an additional delay during graceful shutdown and may restrict nginx from effective connection reuse.
A new directive "ssl_certificate_cache max=N [valid=time] [inactive=time]" enables caching of SSL certificate chain and secret key objects specified by "ssl_certificate" and "ssl_certificate_key" directives with variables. Co-authored-by: Aleksei Bavshin <a.bavshin@nginx.com>
When a request was terminated due to an error via ngx_http_terminate_request()
while an AIO operation was running in a subrequest, various issues were
observed. This happened because ngx_http_request_finalizer() was only set
in the subrequest where ngx_http_terminate_request() was called, but not
in the subrequest where the AIO operation was running. After completion
of the AIO operation normal processing of the subrequest was resumed, leading
to issues.
In particular, in case of the upstream module, termination of the request
called upstream cleanup, which closed the upstream connection. Attempts to
further work with the upstream connection after AIO operation completion
resulted in segfaults in ngx_ssl_recv(), "readv() failed (9: Bad file
descriptor) while reading upstream" errors, or socket leaks.
In ticket #2555, issues were observed with the following configuration
with cache background update (with thread writing instrumented to
introduce a delay, when a client closes the connection during an update):
location = /background-and-aio-write {
proxy_pass ...
proxy_cache one;
proxy_cache_valid 200 1s;
proxy_cache_background_update on;
proxy_cache_use_stale updating;
aio threads;
aio_write on;
limit_rate 1000;
}
Similarly, the same issue can be seen with SSI, and can be caused by
errors in subrequests, such as in the following configuration
(where "/proxy" uses AIO, and "/sleep" returns 444 after some delay,
causing request termination):
location = /ssi-active-boom {
ssi on;
ssi_types *;
return 200 '
<!--#include virtual="/proxy" -->
<!--#include virtual="/sleep" -->
';
limit_rate 1000;
}
Or the same with both AIO operation and the error in non-active subrequests
(which needs slightly different handling, see below):
location = /ssi-non-active-boom {
ssi on;
ssi_types *;
return 200 '
<!--#include virtual="/static" -->
<!--#include virtual="/proxy" -->
<!--#include virtual="/sleep" -->
';
limit_rate 1000;
}
Similarly, issues can be observed with just static files. However,
with static files potential impact is limited due to timeout safeguards
in ngx_http_writer(), and the fact that c->error is set during request
termination.
In a simple configuration with an AIO operation in the active subrequest,
such as in the following configuration, the connection is closed right
after completion of the AIO operation anyway, since ngx_http_writer()
tries to write to the connection and fails due to c->error set:
location = /ssi-active-static-boom {
ssi on;
ssi_types *;
return 200 '
<!--#include virtual="/static-aio" -->
<!--#include virtual="/sleep" -->
';
limit_rate 1000;
}
In the following configuration, with an AIO operation in a non-active
subrequest, the connection is closed only after send_timeout expires:
location = /ssi-non-active-static-boom {
ssi on;
ssi_types *;
return 200 '
<!--#include virtual="/static" -->
<!--#include virtual="/static-aio" -->
<!--#include virtual="/sleep" -->
';
limit_rate 1000;
}
Fix is to introduce r->main->terminated flag, which is to be checked
by AIO event handlers when the r->main->blocked counter is decremented.
When the flag is set, handlers are expected to wake up the connection
instead of the subrequest (which might be already cleaned up).
Additionally, now ngx_http_request_finalizer() is always set in the
active subrequest, so waking up the connection properly finalizes the
request even if termination happened in a non-active subrequest.
If URI is not fully parsed yet, some pointers are not set. As a result, the calculation of "new + (ptr - old)" expression is flawed. According to C11, 6.5.6 Additive operators, p.9: : When two pointers are subtracted, both shall point to elements : of the same array object, or one past the last element of the : array object Since "ptr" is not set, subtraction leads to undefined behaviour, because "ptr" and "old" are not in the same buffer (i.e. array objects). Prodded by GCC undefined behaviour sanitizer.
Neither r->port_start nor r->port_end were ever used. The r->port_end is set by the parser, though it was never used by the following code (and was never usable, since not copied by the ngx_http_alloc_large_header_buffer() without r->port_start set).
It has been deprecated since 7270:46c0c7ef4913 (1.15.0) in favour of the "ssl" parameter of the "listen" directive, which has been available since 2224:109849282793 (0.7.14).
The directive enables HTTP/2 in the current server. The previous way to enable HTTP/2 via "listen ... http2" is now deprecated. The new approach allows to share HTTP/2 and HTTP/0.9-1.1 on the same port. For SSL connections, HTTP/2 is now selected by ALPN callback based on whether the protocol is enabled in the virtual server chosen by SNI. This however only works since OpenSSL 1.0.2h, where ALPN callback is invoked after SNI callback. For older versions of OpenSSL, HTTP/2 is enabled based on the default virtual server configuration. For plain TCP connections, HTTP/2 is now auto-detected by HTTP/2 preface, if HTTP/2 is enabled in the default virtual server. If preface is not matched, HTTP/0.9-1.1 is assumed.
This is expected to help with clients using pipelining with some constant depth, such as apt[1][2]. When downloading many resources, apt uses pipelining with some constant depth, a number of requests in flight. This essentially means that after receiving a response it sends an additional request to the server, and this can result in requests arriving to the server at any time. Further, additional requests are sent one-by-one, and can be easily seen as such (neither as pipelined, nor followed by pipelined requests). The only safe approach to close such connections (for example, when keepalive_requests is reached) is with lingering. To do so, now nginx monitors if pipelining was used on the connection, and if it was, closes the connection with lingering. [1] https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=973861#10 [2] https://mailman.nginx.org/pipermail/nginx-devel/2023-January/ZA2SP5SJU55LHEBCJMFDB2AZVELRLTHI.html