Cache: ignore stale-if-error for 4xx and 5xx codes. Previously the stale-if-error extension of the Cache-Control upstream header triggered the return of a stale response for all error conditions that can be specified in the proxy_cache_use_stale directive. The list of these errors includes both network/timeout/format errors, as well as some HTTP codes like 503, 504, 403, 429 etc. The latter prevented a cache entry from being updated by a response with any of these HTTP codes during the stale-if-error period. Now stale-if-error only works for network/timeout/format errors and ignores the upstream HTTP code. The return of a stale response for certain HTTP codes is still possible using the proxy_cache_use_stale directive. This change also applies to the stale-while-revalidate extension of the Cache-Control header, which triggers stale-if-error if it is missing. Reported at http://mailman.nginx.org/pipermail/nginx/2020-July/059723.html.

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


#ifndef _NGX_MAIL_POP3_MODULE_H_INCLUDED_
#define _NGX_MAIL_POP3_MODULE_H_INCLUDED_


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


typedef struct {
    ngx_str_t    capability;
    ngx_str_t    starttls_capability;
    ngx_str_t    starttls_only_capability;
    ngx_str_t    auth_capability;

    ngx_uint_t   auth_methods;

    ngx_array_t  capabilities;
} ngx_mail_pop3_srv_conf_t;


void ngx_mail_pop3_init_session(ngx_mail_session_t *s, ngx_connection_t *c);
void ngx_mail_pop3_init_protocol(ngx_event_t *rev);
void ngx_mail_pop3_auth_state(ngx_event_t *rev);
ngx_int_t ngx_mail_pop3_parse_command(ngx_mail_session_t *s);


extern ngx_module_t  ngx_mail_pop3_module;


#endif /* _NGX_MAIL_POP3_MODULE_H_INCLUDED_ */