view src/core/ngx_shmtx.h @ 8484:3e78c12d4f37 stable-1.20

Resolver: explicit check for compression pointers in question. Since nginx always uses exactly one entry in the question section of a DNS query, and never uses compression pointers in this entry, parsing of a DNS response in ngx_resolver_process_response() does not expect compression pointers to appear in the question section of the DNS response. Indeed, compression pointers in the first name of a DNS response hardly make sense, do not seem to be allowed by RFC 1035 (which says "a pointer to a prior occurance of the same name", note "prior"), and were never observed in practice. Added an explicit check to ngx_resolver_process_response()'s parsing of the question section to properly report an error if compression pointers nevertheless appear in the question section.
author Maxim Dounin <mdounin@mdounin.ru>
date Tue, 25 May 2021 15:17:50 +0300
parents 512c741fa841
children
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/*
 * Copyright (C) Igor Sysoev
 * Copyright (C) Nginx, Inc.
 */


#ifndef _NGX_SHMTX_H_INCLUDED_
#define _NGX_SHMTX_H_INCLUDED_


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


typedef struct {
    ngx_atomic_t   lock;
#if (NGX_HAVE_POSIX_SEM)
    ngx_atomic_t   wait;
#endif
} ngx_shmtx_sh_t;


typedef struct {
#if (NGX_HAVE_ATOMIC_OPS)
    ngx_atomic_t  *lock;
#if (NGX_HAVE_POSIX_SEM)
    ngx_atomic_t  *wait;
    ngx_uint_t     semaphore;
    sem_t          sem;
#endif
#else
    ngx_fd_t       fd;
    u_char        *name;
#endif
    ngx_uint_t     spin;
} ngx_shmtx_t;


ngx_int_t ngx_shmtx_create(ngx_shmtx_t *mtx, ngx_shmtx_sh_t *addr,
    u_char *name);
void ngx_shmtx_destroy(ngx_shmtx_t *mtx);
ngx_uint_t ngx_shmtx_trylock(ngx_shmtx_t *mtx);
void ngx_shmtx_lock(ngx_shmtx_t *mtx);
void ngx_shmtx_unlock(ngx_shmtx_t *mtx);
ngx_uint_t ngx_shmtx_force_unlock(ngx_shmtx_t *mtx, ngx_pid_t pid);


#endif /* _NGX_SHMTX_H_INCLUDED_ */