Mercurial > hg > nginx
view src/core/ngx_resolver.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 | 2a77754cd9fe |
children |
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/* * Copyright (C) Igor Sysoev * Copyright (C) Nginx, Inc. */ #include <ngx_config.h> #include <ngx_core.h> #ifndef _NGX_RESOLVER_H_INCLUDED_ #define _NGX_RESOLVER_H_INCLUDED_ #define NGX_RESOLVE_A 1 #define NGX_RESOLVE_CNAME 5 #define NGX_RESOLVE_PTR 12 #define NGX_RESOLVE_MX 15 #define NGX_RESOLVE_TXT 16 #if (NGX_HAVE_INET6) #define NGX_RESOLVE_AAAA 28 #endif #define NGX_RESOLVE_SRV 33 #define NGX_RESOLVE_DNAME 39 #define NGX_RESOLVE_FORMERR 1 #define NGX_RESOLVE_SERVFAIL 2 #define NGX_RESOLVE_NXDOMAIN 3 #define NGX_RESOLVE_NOTIMP 4 #define NGX_RESOLVE_REFUSED 5 #define NGX_RESOLVE_TIMEDOUT NGX_ETIMEDOUT #define NGX_NO_RESOLVER (void *) -1 #define NGX_RESOLVER_MAX_RECURSION 50 typedef struct ngx_resolver_s ngx_resolver_t; typedef struct { ngx_connection_t *udp; ngx_connection_t *tcp; struct sockaddr *sockaddr; socklen_t socklen; ngx_str_t server; ngx_log_t log; ngx_buf_t *read_buf; ngx_buf_t *write_buf; ngx_resolver_t *resolver; } ngx_resolver_connection_t; typedef struct ngx_resolver_ctx_s ngx_resolver_ctx_t; typedef void (*ngx_resolver_handler_pt)(ngx_resolver_ctx_t *ctx); typedef struct { struct sockaddr *sockaddr; socklen_t socklen; ngx_str_t name; u_short priority; u_short weight; } ngx_resolver_addr_t; typedef struct { ngx_str_t name; u_short priority; u_short weight; u_short port; } ngx_resolver_srv_t; typedef struct { ngx_str_t name; u_short priority; u_short weight; u_short port; ngx_resolver_ctx_t *ctx; ngx_int_t state; ngx_uint_t naddrs; ngx_addr_t *addrs; } ngx_resolver_srv_name_t; typedef struct { ngx_rbtree_node_t node; ngx_queue_t queue; /* PTR: resolved name, A: name to resolve */ u_char *name; #if (NGX_HAVE_INET6) /* PTR: IPv6 address to resolve (IPv4 address is in rbtree node key) */ struct in6_addr addr6; #endif u_short nlen; u_short qlen; u_char *query; #if (NGX_HAVE_INET6) u_char *query6; #endif union { in_addr_t addr; in_addr_t *addrs; u_char *cname; ngx_resolver_srv_t *srvs; } u; u_char code; u_short naddrs; u_short nsrvs; u_short cnlen; #if (NGX_HAVE_INET6) union { struct in6_addr addr6; struct in6_addr *addrs6; } u6; u_short naddrs6; #endif time_t expire; time_t valid; uint32_t ttl; unsigned tcp:1; #if (NGX_HAVE_INET6) unsigned tcp6:1; #endif ngx_uint_t last_connection; ngx_resolver_ctx_t *waiting; } ngx_resolver_node_t; struct ngx_resolver_s { /* has to be pointer because of "incomplete type" */ ngx_event_t *event; void *dummy; ngx_log_t *log; /* event ident must be after 3 pointers as in ngx_connection_t */ ngx_int_t ident; /* simple round robin DNS peers balancer */ ngx_array_t connections; ngx_uint_t last_connection; ngx_rbtree_t name_rbtree; ngx_rbtree_node_t name_sentinel; ngx_rbtree_t srv_rbtree; ngx_rbtree_node_t srv_sentinel; ngx_rbtree_t addr_rbtree; ngx_rbtree_node_t addr_sentinel; ngx_queue_t name_resend_queue; ngx_queue_t srv_resend_queue; ngx_queue_t addr_resend_queue; ngx_queue_t name_expire_queue; ngx_queue_t srv_expire_queue; ngx_queue_t addr_expire_queue; unsigned ipv4:1; #if (NGX_HAVE_INET6) unsigned ipv6:1; ngx_rbtree_t addr6_rbtree; ngx_rbtree_node_t addr6_sentinel; ngx_queue_t addr6_resend_queue; ngx_queue_t addr6_expire_queue; #endif time_t resend_timeout; time_t tcp_timeout; time_t expire; time_t valid; ngx_uint_t log_level; }; struct ngx_resolver_ctx_s { ngx_resolver_ctx_t *next; ngx_resolver_t *resolver; ngx_resolver_node_t *node; /* event ident must be after 3 pointers as in ngx_connection_t */ ngx_int_t ident; ngx_int_t state; ngx_str_t name; ngx_str_t service; time_t valid; ngx_uint_t naddrs; ngx_resolver_addr_t *addrs; ngx_resolver_addr_t addr; struct sockaddr_in sin; ngx_uint_t count; ngx_uint_t nsrvs; ngx_resolver_srv_name_t *srvs; ngx_resolver_handler_pt handler; void *data; ngx_msec_t timeout; unsigned quick:1; unsigned async:1; unsigned cancelable:1; ngx_uint_t recursion; ngx_event_t *event; }; ngx_resolver_t *ngx_resolver_create(ngx_conf_t *cf, ngx_str_t *names, ngx_uint_t n); ngx_resolver_ctx_t *ngx_resolve_start(ngx_resolver_t *r, ngx_resolver_ctx_t *temp); ngx_int_t ngx_resolve_name(ngx_resolver_ctx_t *ctx); void ngx_resolve_name_done(ngx_resolver_ctx_t *ctx); ngx_int_t ngx_resolve_addr(ngx_resolver_ctx_t *ctx); void ngx_resolve_addr_done(ngx_resolver_ctx_t *ctx); char *ngx_resolver_strerror(ngx_int_t err); #endif /* _NGX_RESOLVER_H_INCLUDED_ */