Upstream: fixed X-Accel-Redirect handling from cache files. The X-Accel-Redirect header might appear in cache files if its handling is ignored with the "proxy_ignore_headers" directive. If the cache file is later served with different settings, ngx_http_upstream_process_headers() used to call ngx_http_upstream_finalize_request(NGX_DECLINED), which is not expected to happen before the cleanup handler is installed and resulted in ngx_http_finalize_request(NGX_DONE) (after 5994:5abf5af257a7, nginx 1.7.11), leading to unexpected request counter decrement, "request count is zero" alerts, and segmentation faults. Similarly, errors in ngx_http_upstream_process_headers() resulted in ngx_http_upstream_finalize_request(NGX_HTTP_INTERNAL_SERVER_ERROR) being called. This is also not expected to happen before the cleanup handler is installed, and resulted in ngx_http_finalize_request(NGX_DONE) without proper request finalization. Fix is to avoid calling ngx_http_upstream_finalize_request() from ngx_http_upstream_process_headers(), notably when the cleanup handler is not yet installed. Errors are now simply return NGX_ERROR, so the caller is responsible for proper finalization by calling either ngx_http_finalize_request() or ngx_http_upstream_finalize_request(). And X-Accel-Redirect handling now does not call ngx_http_upstream_finalize_request(NGX_DECLINED) if no cleanup handler is installed. Reported by Jiří Setnička (https://mailman.nginx.org/pipermail/nginx-devel/2024-February/HWLYHOO3DDB3XTFT6X3GRMXIEJ3SJRUA.html).

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


#ifndef _NGX_EVENT_UDP_H_INCLUDED_
#define _NGX_EVENT_UDP_H_INCLUDED_


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


#if !(NGX_WIN32)

#if ((NGX_HAVE_MSGHDR_MSG_CONTROL)                                            \
     && (NGX_HAVE_IP_SENDSRCADDR || NGX_HAVE_IP_RECVDSTADDR                   \
         || NGX_HAVE_IP_PKTINFO                                               \
         || (NGX_HAVE_INET6 && NGX_HAVE_IPV6_RECVPKTINFO)))
#define NGX_HAVE_ADDRINFO_CMSG  1

#endif


struct ngx_udp_connection_s {
    ngx_rbtree_node_t   node;
    ngx_connection_t   *connection;
    ngx_buf_t          *buffer;
    ngx_str_t           key;
};


#if (NGX_HAVE_ADDRINFO_CMSG)

typedef union {
#if (NGX_HAVE_IP_SENDSRCADDR || NGX_HAVE_IP_RECVDSTADDR)
    struct in_addr        addr;
#endif

#if (NGX_HAVE_IP_PKTINFO)
    struct in_pktinfo     pkt;
#endif

#if (NGX_HAVE_INET6 && NGX_HAVE_IPV6_RECVPKTINFO)
    struct in6_pktinfo    pkt6;
#endif
} ngx_addrinfo_t;

size_t ngx_set_srcaddr_cmsg(struct cmsghdr *cmsg,
    struct sockaddr *local_sockaddr);
ngx_int_t ngx_get_srcaddr_cmsg(struct cmsghdr *cmsg,
    struct sockaddr *local_sockaddr);

#endif

void ngx_event_recvmsg(ngx_event_t *ev);
ssize_t ngx_sendmsg(ngx_connection_t *c, struct msghdr *msg, int flags);
void ngx_udp_rbtree_insert_value(ngx_rbtree_node_t *temp,
    ngx_rbtree_node_t *node, ngx_rbtree_node_t *sentinel);
#endif

void ngx_delete_udp_connection(void *data);


#endif /* _NGX_EVENT_UDP_H_INCLUDED_ */