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view src/core/ngx_resolver.h @ 6806:75dbab4ea930

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Events: improved error event handling for UDP sockets. Normally, the epoll module calls the read and write handlers depending on whether EPOLLIN and EPOLLOUT are reported by epoll_wait(). No error processing is done in the module, the handlers are expected to get an error when doing I/O. If an error event is reported without EPOLLIN and EPOLLOUT, the module set both EPOLLIN and EPOLLOUT to ensure the error event is handled at least in one active handler. This works well unless the error is delivered along with only one of EPOLLIN or EPOLLOUT, and the corresponding handler does not do any I/O. For example, it happened when getting EPOLLERR|EPOLLOUT from epoll_wait() upon receiving "ICMP port unreachable" while proxying UDP. As the write handler had nothing to send it was not able to detect and log an error, and did not switch to the next upstream. The fix is to unconditionally set EPOLLIN and EPOLLOUT in case of an error event. In the aforementioned case, this causes the read handler to be called which does recv() and detects an error. In addition to the epoll module, analogous changes were made in devpoll/eventport/poll.
author Dmitry Volyntsev <xeioex@nginx.com>
date Mon, 21 Nov 2016 16:03:42 +0300
parents c3e3de6d2672
children d49b74a683b1
line wrap: on
line source


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


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


#ifndef _NGX_RESOLVER_H_INCLUDED_
#define _NGX_RESOLVER_H_INCLUDED_


#define NGX_RESOLVE_A         1
#define NGX_RESOLVE_CNAME     5
#define NGX_RESOLVE_PTR       12
#define NGX_RESOLVE_MX        15
#define NGX_RESOLVE_TXT       16
#if (NGX_HAVE_INET6)
#define NGX_RESOLVE_AAAA      28
#endif
#define NGX_RESOLVE_SRV       33
#define NGX_RESOLVE_DNAME     39

#define NGX_RESOLVE_FORMERR   1
#define NGX_RESOLVE_SERVFAIL  2
#define NGX_RESOLVE_NXDOMAIN  3
#define NGX_RESOLVE_NOTIMP    4
#define NGX_RESOLVE_REFUSED   5
#define NGX_RESOLVE_TIMEDOUT  NGX_ETIMEDOUT


#define NGX_NO_RESOLVER       (void *) -1

#define NGX_RESOLVER_MAX_RECURSION    50


typedef struct ngx_resolver_s  ngx_resolver_t;


typedef struct {
    ngx_connection_t         *udp;
    ngx_connection_t         *tcp;
    struct sockaddr          *sockaddr;
    socklen_t                 socklen;
    ngx_str_t                 server;
    ngx_log_t                 log;
    ngx_buf_t                *read_buf;
    ngx_buf_t                *write_buf;
    ngx_resolver_t           *resolver;
} ngx_resolver_connection_t;


typedef struct ngx_resolver_ctx_s  ngx_resolver_ctx_t;

typedef void (*ngx_resolver_handler_pt)(ngx_resolver_ctx_t *ctx);


typedef struct {
    struct sockaddr          *sockaddr;
    socklen_t                 socklen;
    ngx_str_t                 name;
    u_short                   priority;
    u_short                   weight;
} ngx_resolver_addr_t;


typedef struct {
    ngx_str_t                 name;
    u_short                   priority;
    u_short                   weight;
    u_short                   port;
} ngx_resolver_srv_t;


typedef struct {
    ngx_str_t                 name;
    u_short                   priority;
    u_short                   weight;
    u_short                   port;

    ngx_resolver_ctx_t       *ctx;
    ngx_int_t                 state;

    ngx_uint_t                naddrs;
    ngx_addr_t               *addrs;
} ngx_resolver_srv_name_t;


typedef struct {
    ngx_rbtree_node_t         node;
    ngx_queue_t               queue;

    /* PTR: resolved name, A: name to resolve */
    u_char                   *name;

#if (NGX_HAVE_INET6)
    /* PTR: IPv6 address to resolve (IPv4 address is in rbtree node key) */
    struct in6_addr           addr6;
#endif

    u_short                   nlen;
    u_short                   qlen;

    u_char                   *query;
#if (NGX_HAVE_INET6)
    u_char                   *query6;
#endif

    union {
        in_addr_t             addr;
        in_addr_t            *addrs;
        u_char               *cname;
        ngx_resolver_srv_t   *srvs;
    } u;

    u_char                    code;
    u_short                   naddrs;
    u_short                   nsrvs;
    u_short                   cnlen;

#if (NGX_HAVE_INET6)
    union {
        struct in6_addr       addr6;
        struct in6_addr      *addrs6;
    } u6;

    u_short                   naddrs6;
#endif

    time_t                    expire;
    time_t                    valid;
    uint32_t                  ttl;

    unsigned                  tcp:1;
#if (NGX_HAVE_INET6)
    unsigned                  tcp6:1;
#endif

    ngx_uint_t                last_connection;

    ngx_resolver_ctx_t       *waiting;
} ngx_resolver_node_t;


struct ngx_resolver_s {
    /* has to be pointer because of "incomplete type" */
    ngx_event_t              *event;
    void                     *dummy;
    ngx_log_t                *log;

    /* event ident must be after 3 pointers as in ngx_connection_t */
    ngx_int_t                 ident;

    /* simple round robin DNS peers balancer */
    ngx_array_t               connections;
    ngx_uint_t                last_connection;

    ngx_rbtree_t              name_rbtree;
    ngx_rbtree_node_t         name_sentinel;

    ngx_rbtree_t              srv_rbtree;
    ngx_rbtree_node_t         srv_sentinel;

    ngx_rbtree_t              addr_rbtree;
    ngx_rbtree_node_t         addr_sentinel;

    ngx_queue_t               name_resend_queue;
    ngx_queue_t               srv_resend_queue;
    ngx_queue_t               addr_resend_queue;

    ngx_queue_t               name_expire_queue;
    ngx_queue_t               srv_expire_queue;
    ngx_queue_t               addr_expire_queue;

#if (NGX_HAVE_INET6)
    ngx_uint_t                ipv6;                 /* unsigned  ipv6:1; */
    ngx_rbtree_t              addr6_rbtree;
    ngx_rbtree_node_t         addr6_sentinel;
    ngx_queue_t               addr6_resend_queue;
    ngx_queue_t               addr6_expire_queue;
#endif

    time_t                    resend_timeout;
    time_t                    tcp_timeout;
    time_t                    expire;
    time_t                    valid;

    ngx_uint_t                log_level;
};


struct ngx_resolver_ctx_s {
    ngx_resolver_ctx_t       *next;
    ngx_resolver_t           *resolver;
    ngx_resolver_node_t      *node;

    /* event ident must be after 3 pointers as in ngx_connection_t */
    ngx_int_t                 ident;

    ngx_int_t                 state;
    ngx_str_t                 name;
    ngx_str_t                 service;

    time_t                    valid;
    ngx_uint_t                naddrs;
    ngx_resolver_addr_t      *addrs;
    ngx_resolver_addr_t       addr;
    struct sockaddr_in        sin;

    ngx_uint_t                count;
    ngx_uint_t                nsrvs;
    ngx_resolver_srv_name_t  *srvs;

    ngx_resolver_handler_pt   handler;
    void                     *data;
    ngx_msec_t                timeout;

    ngx_uint_t                quick;  /* unsigned  quick:1; */
    ngx_uint_t                recursion;
    ngx_event_t              *event;
};


ngx_resolver_t *ngx_resolver_create(ngx_conf_t *cf, ngx_str_t *names,
    ngx_uint_t n);
ngx_resolver_ctx_t *ngx_resolve_start(ngx_resolver_t *r,
    ngx_resolver_ctx_t *temp);
ngx_int_t ngx_resolve_name(ngx_resolver_ctx_t *ctx);
void ngx_resolve_name_done(ngx_resolver_ctx_t *ctx);
ngx_int_t ngx_resolve_addr(ngx_resolver_ctx_t *ctx);
void ngx_resolve_addr_done(ngx_resolver_ctx_t *ctx);
char *ngx_resolver_strerror(ngx_int_t err);


#endif /* _NGX_RESOLVER_H_INCLUDED_ */