view src/http/ngx_http_script.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 3ab8e1e2f0f7
children
line wrap: on
line source


/*
 * Copyright (C) Igor Sysoev
 * Copyright (C) Nginx, Inc.
 */


#ifndef _NGX_HTTP_SCRIPT_H_INCLUDED_
#define _NGX_HTTP_SCRIPT_H_INCLUDED_


#include <ngx_config.h>
#include <ngx_core.h>
#include <ngx_http.h>


typedef struct {
    u_char                     *ip;
    u_char                     *pos;
    ngx_http_variable_value_t  *sp;

    ngx_str_t                   buf;
    ngx_str_t                   line;

    /* the start of the rewritten arguments */
    u_char                     *args;

    unsigned                    flushed:1;
    unsigned                    skip:1;
    unsigned                    quote:1;
    unsigned                    is_args:1;
    unsigned                    log:1;

    ngx_int_t                   status;
    ngx_http_request_t         *request;
} ngx_http_script_engine_t;


typedef struct {
    ngx_conf_t                 *cf;
    ngx_str_t                  *source;

    ngx_array_t               **flushes;
    ngx_array_t               **lengths;
    ngx_array_t               **values;

    ngx_uint_t                  variables;
    ngx_uint_t                  ncaptures;
    ngx_uint_t                  captures_mask;
    ngx_uint_t                  size;

    void                       *main;

    unsigned                    compile_args:1;
    unsigned                    complete_lengths:1;
    unsigned                    complete_values:1;
    unsigned                    zero:1;
    unsigned                    conf_prefix:1;
    unsigned                    root_prefix:1;

    unsigned                    dup_capture:1;
    unsigned                    args:1;
} ngx_http_script_compile_t;


typedef struct {
    ngx_str_t                   value;
    ngx_uint_t                 *flushes;
    void                       *lengths;
    void                       *values;

    union {
        size_t                  size;
    } u;
} ngx_http_complex_value_t;


typedef struct {
    ngx_conf_t                 *cf;
    ngx_str_t                  *value;
    ngx_http_complex_value_t   *complex_value;

    unsigned                    zero:1;
    unsigned                    conf_prefix:1;
    unsigned                    root_prefix:1;
} ngx_http_compile_complex_value_t;


typedef void (*ngx_http_script_code_pt) (ngx_http_script_engine_t *e);
typedef size_t (*ngx_http_script_len_code_pt) (ngx_http_script_engine_t *e);


typedef struct {
    ngx_http_script_code_pt     code;
    uintptr_t                   len;
} ngx_http_script_copy_code_t;


typedef struct {
    ngx_http_script_code_pt     code;
    uintptr_t                   index;
} ngx_http_script_var_code_t;


typedef struct {
    ngx_http_script_code_pt     code;
    ngx_http_set_variable_pt    handler;
    uintptr_t                   data;
} ngx_http_script_var_handler_code_t;


typedef struct {
    ngx_http_script_code_pt     code;
    uintptr_t                   n;
} ngx_http_script_copy_capture_code_t;


#if (NGX_PCRE)

typedef struct {
    ngx_http_script_code_pt     code;
    ngx_http_regex_t           *regex;
    ngx_array_t                *lengths;
    uintptr_t                   size;
    uintptr_t                   status;
    uintptr_t                   next;

    unsigned                    test:1;
    unsigned                    negative_test:1;
    unsigned                    uri:1;
    unsigned                    args:1;

    /* add the r->args to the new arguments */
    unsigned                    add_args:1;

    unsigned                    redirect:1;
    unsigned                    break_cycle:1;

    ngx_str_t                   name;
} ngx_http_script_regex_code_t;


typedef struct {
    ngx_http_script_code_pt     code;

    unsigned                    uri:1;
    unsigned                    args:1;

    /* add the r->args to the new arguments */
    unsigned                    add_args:1;

    unsigned                    redirect:1;
} ngx_http_script_regex_end_code_t;

#endif


typedef struct {
    ngx_http_script_code_pt     code;
    uintptr_t                   conf_prefix;
} ngx_http_script_full_name_code_t;


typedef struct {
    ngx_http_script_code_pt     code;
    uintptr_t                   status;
    ngx_http_complex_value_t    text;
} ngx_http_script_return_code_t;


typedef enum {
    ngx_http_script_file_plain = 0,
    ngx_http_script_file_not_plain,
    ngx_http_script_file_dir,
    ngx_http_script_file_not_dir,
    ngx_http_script_file_exists,
    ngx_http_script_file_not_exists,
    ngx_http_script_file_exec,
    ngx_http_script_file_not_exec
} ngx_http_script_file_op_e;


typedef struct {
    ngx_http_script_code_pt     code;
    uintptr_t                   op;
} ngx_http_script_file_code_t;


typedef struct {
    ngx_http_script_code_pt     code;
    uintptr_t                   next;
    void                      **loc_conf;
} ngx_http_script_if_code_t;


typedef struct {
    ngx_http_script_code_pt     code;
    ngx_array_t                *lengths;
} ngx_http_script_complex_value_code_t;


typedef struct {
    ngx_http_script_code_pt     code;
    uintptr_t                   value;
    uintptr_t                   text_len;
    uintptr_t                   text_data;
} ngx_http_script_value_code_t;


void ngx_http_script_flush_complex_value(ngx_http_request_t *r,
    ngx_http_complex_value_t *val);
ngx_int_t ngx_http_complex_value(ngx_http_request_t *r,
    ngx_http_complex_value_t *val, ngx_str_t *value);
size_t ngx_http_complex_value_size(ngx_http_request_t *r,
    ngx_http_complex_value_t *val, size_t default_value);
ngx_int_t ngx_http_compile_complex_value(ngx_http_compile_complex_value_t *ccv);
char *ngx_http_set_complex_value_slot(ngx_conf_t *cf, ngx_command_t *cmd,
    void *conf);
char *ngx_http_set_complex_value_zero_slot(ngx_conf_t *cf, ngx_command_t *cmd,
    void *conf);
char *ngx_http_set_complex_value_size_slot(ngx_conf_t *cf, ngx_command_t *cmd,
    void *conf);


ngx_int_t ngx_http_test_predicates(ngx_http_request_t *r,
    ngx_array_t *predicates);
ngx_int_t ngx_http_test_required_predicates(ngx_http_request_t *r,
    ngx_array_t *predicates);
char *ngx_http_set_predicate_slot(ngx_conf_t *cf, ngx_command_t *cmd,
    void *conf);

ngx_uint_t ngx_http_script_variables_count(ngx_str_t *value);
ngx_int_t ngx_http_script_compile(ngx_http_script_compile_t *sc);
u_char *ngx_http_script_run(ngx_http_request_t *r, ngx_str_t *value,
    void *code_lengths, size_t reserved, void *code_values);
void ngx_http_script_flush_no_cacheable_variables(ngx_http_request_t *r,
    ngx_array_t *indices);

void *ngx_http_script_start_code(ngx_pool_t *pool, ngx_array_t **codes,
    size_t size);
void *ngx_http_script_add_code(ngx_array_t *codes, size_t size, void *code);

size_t ngx_http_script_copy_len_code(ngx_http_script_engine_t *e);
void ngx_http_script_copy_code(ngx_http_script_engine_t *e);
size_t ngx_http_script_copy_var_len_code(ngx_http_script_engine_t *e);
void ngx_http_script_copy_var_code(ngx_http_script_engine_t *e);
size_t ngx_http_script_copy_capture_len_code(ngx_http_script_engine_t *e);
void ngx_http_script_copy_capture_code(ngx_http_script_engine_t *e);
size_t ngx_http_script_mark_args_code(ngx_http_script_engine_t *e);
void ngx_http_script_start_args_code(ngx_http_script_engine_t *e);
#if (NGX_PCRE)
void ngx_http_script_regex_start_code(ngx_http_script_engine_t *e);
void ngx_http_script_regex_end_code(ngx_http_script_engine_t *e);
#endif
void ngx_http_script_return_code(ngx_http_script_engine_t *e);
void ngx_http_script_break_code(ngx_http_script_engine_t *e);
void ngx_http_script_if_code(ngx_http_script_engine_t *e);
void ngx_http_script_equal_code(ngx_http_script_engine_t *e);
void ngx_http_script_not_equal_code(ngx_http_script_engine_t *e);
void ngx_http_script_file_code(ngx_http_script_engine_t *e);
void ngx_http_script_complex_value_code(ngx_http_script_engine_t *e);
void ngx_http_script_value_code(ngx_http_script_engine_t *e);
void ngx_http_script_set_var_code(ngx_http_script_engine_t *e);
void ngx_http_script_var_set_handler_code(ngx_http_script_engine_t *e);
void ngx_http_script_var_code(ngx_http_script_engine_t *e);
void ngx_http_script_nop_code(ngx_http_script_engine_t *e);


#endif /* _NGX_HTTP_SCRIPT_H_INCLUDED_ */