view src/http/ngx_http_variables.h @ 8018:5119c8150478

Fixed runtime handling of systems without EPOLLRDHUP support. In 7583:efd71d49bde0 (nginx 1.17.5) along with introduction of the ioctl(FIONREAD) support proper handling of systems without EPOLLRDHUP support in the kernel (but with EPOLLRDHUP in headers) was broken. Before the change, rev->available was never set to 0 unless ngx_use_epoll_rdhup was also set (that is, runtime test for EPOLLRDHUP introduced in 6536:f7849bfb6d21 succeeded). After the change, rev->available might reach 0 on systems without runtime EPOLLRDHUP support, stopping further reading in ngx_readv_chain() and ngx_unix_recv(). And, if EOF happened to be already reported along with the last event, it is not reported again by epoll_wait(), leading to connection hangs and timeouts on such systems. This affects Linux kernels before 2.6.17 if nginx was compiled with newer headers, and, more importantly, emulation layers, such as DigitalOcean's App Platform's / gVisor's epoll emulation layer. Fix is to explicitly check ngx_use_epoll_rdhup before the corresponding rev->pending_eof tests in ngx_readv_chain() and ngx_unix_recv().
author Marcus Ball <marcus.ball@live.com>
date Mon, 30 May 2022 02:38:07 +0300
parents 2a288909abc6
children 08b3ea81ff5f
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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_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_ */