Mercurial > hg > nginx
view src/http/ngx_http_variables.h @ 9203:0de20f43db25
Fixed request termination with AIO and subrequests (ticket #2555).
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.
author | Maxim Dounin <mdounin@mdounin.ru> |
---|---|
date | Tue, 30 Jan 2024 03:20:05 +0300 |
parents | 08b3ea81ff5f |
children |
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/* * Copyright (C) Igor Sysoev * Copyright (C) Nginx, Inc. */ #ifndef _NGX_HTTP_VARIABLES_H_INCLUDED_ #define _NGX_HTTP_VARIABLES_H_INCLUDED_ #include <ngx_config.h> #include <ngx_core.h> #include <ngx_http.h> typedef ngx_variable_value_t ngx_http_variable_value_t; #define ngx_http_variable(v) { sizeof(v) - 1, 1, 0, 0, 0, (u_char *) v } typedef struct ngx_http_variable_s ngx_http_variable_t; typedef void (*ngx_http_set_variable_pt) (ngx_http_request_t *r, ngx_http_variable_value_t *v, uintptr_t data); typedef ngx_int_t (*ngx_http_get_variable_pt) (ngx_http_request_t *r, ngx_http_variable_value_t *v, uintptr_t data); #define NGX_HTTP_VAR_CHANGEABLE 1 #define NGX_HTTP_VAR_NOCACHEABLE 2 #define NGX_HTTP_VAR_INDEXED 4 #define NGX_HTTP_VAR_NOHASH 8 #define NGX_HTTP_VAR_WEAK 16 #define NGX_HTTP_VAR_PREFIX 32 struct ngx_http_variable_s { ngx_str_t name; /* must be first to build the hash */ ngx_http_set_variable_pt set_handler; ngx_http_get_variable_pt get_handler; uintptr_t data; ngx_uint_t flags; ngx_uint_t index; }; #define ngx_http_null_variable { ngx_null_string, NULL, NULL, 0, 0, 0 } ngx_http_variable_t *ngx_http_add_variable(ngx_conf_t *cf, ngx_str_t *name, ngx_uint_t flags); ngx_int_t ngx_http_get_variable_index(ngx_conf_t *cf, ngx_str_t *name); ngx_http_variable_value_t *ngx_http_get_indexed_variable(ngx_http_request_t *r, ngx_uint_t index); ngx_http_variable_value_t *ngx_http_get_flushed_variable(ngx_http_request_t *r, ngx_uint_t index); ngx_http_variable_value_t *ngx_http_get_variable(ngx_http_request_t *r, ngx_str_t *name, ngx_uint_t key); ngx_int_t ngx_http_variable_unknown_header(ngx_http_request_t *r, ngx_http_variable_value_t *v, ngx_str_t *var, ngx_list_part_t *part, size_t prefix); #if (NGX_PCRE) typedef struct { ngx_uint_t capture; ngx_int_t index; } ngx_http_regex_variable_t; typedef struct { ngx_regex_t *regex; ngx_uint_t ncaptures; ngx_http_regex_variable_t *variables; ngx_uint_t nvariables; ngx_str_t name; } ngx_http_regex_t; typedef struct { ngx_http_regex_t *regex; void *value; } ngx_http_map_regex_t; ngx_http_regex_t *ngx_http_regex_compile(ngx_conf_t *cf, ngx_regex_compile_t *rc); ngx_int_t ngx_http_regex_exec(ngx_http_request_t *r, ngx_http_regex_t *re, ngx_str_t *s); #endif typedef struct { ngx_hash_combined_t hash; #if (NGX_PCRE) ngx_http_map_regex_t *regex; ngx_uint_t nregex; #endif } ngx_http_map_t; void *ngx_http_map_find(ngx_http_request_t *r, ngx_http_map_t *map, ngx_str_t *match); ngx_int_t ngx_http_variables_add_core_vars(ngx_conf_t *cf); ngx_int_t ngx_http_variables_init_vars(ngx_conf_t *cf); extern ngx_http_variable_value_t ngx_http_variable_null_value; extern ngx_http_variable_value_t ngx_http_variable_true_value; #endif /* _NGX_HTTP_VARIABLES_H_INCLUDED_ */