Upstream: fixed proxy_no_cache when caching errors. Caching errors, notably intercepted errors and internally generated 502/504 errors, as well as handling of cache revalidation with 304, did not take into account u->conf->no_cache predicates configured. As a result, an error might be cached even if configuration explicitly says not to. Fix is to check u->conf->no_cache in these cases. To simplify usage in multiple places, checking u->conf->no_cache is now done in a separate function. As a minor optimization, u->conf->no_cache is only checked if u->cacheable is set. As a side effect, this change also fixes caching errors after proxy_cache_bypass. Also, during cache revalidation u->cacheable is now tested, so 304 responses which disable caching won't extend cacheability of stored responses. Additionally, when caching internally generated 502/504 errors u->cacheable is now explicitly updated from u->headers_in.no_cache and u->headers_in.expired, restoring the behaviour before 8041:0784ab86ad08 (1.23.0) when an error happens while reading the response headers. Reported by Kirill A. Korinsky, https://freenginx.org/pipermail/nginx/2024-April/000082.html

/*
 * Copyright (C) Maxim Dounin
 * Copyright (C) Nginx, Inc.
 */


#ifndef _NGX_DLOPEN_H_INCLUDED_
#define _NGX_DLOPEN_H_INCLUDED_


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


#define NGX_HAVE_DLOPEN  1


#define ngx_dlopen(path)           LoadLibrary((char *) path)
#define ngx_dlopen_n               "LoadLibrary()"

#define ngx_dlsym(handle, symbol)  (void *) GetProcAddress(handle, symbol)
#define ngx_dlsym_n                "GetProcAddress()"

#define ngx_dlclose(handle)        (FreeLibrary(handle) ? 0 : -1)
#define ngx_dlclose_n              "FreeLibrary()"


char *ngx_dlerror(void);


#endif /* _NGX_DLOPEN_H_INCLUDED_ */