Mercurial > hg > nginx-quic
annotate src/core/ngx_resolver.h @ 6366:2e5c027f2a98
Resolver: per-request DNS server balancer.
Previously, a global server balancer was used to assign the next DNS server to
send a query to. That could lead to a non-uniform distribution of servers per
request. A request could be assigned to the same dead server several times in a
row and wait longer for a valid server or even time out without being processed.
Now each query is sent to all servers sequentially in a circle until a
response is received or timeout expires. Initial server for each request is
still globally balanced.
author | Roman Arutyunyan <arut@nginx.com> |
---|---|
date | Thu, 28 Jan 2016 15:28:20 +0300 |
parents | d35b4d590b2d |
children | 5a16d40c63de |
rev | line source |
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1649 | 1 |
2 /* | |
3 * Copyright (C) Igor Sysoev | |
4412 | 4 * Copyright (C) Nginx, Inc. |
1649 | 5 */ |
6 | |
7 | |
8 #include <ngx_config.h> | |
9 #include <ngx_core.h> | |
10 | |
11 | |
12 #ifndef _NGX_RESOLVER_H_INCLUDED_ | |
13 #define _NGX_RESOLVER_H_INCLUDED_ | |
14 | |
15 | |
16 #define NGX_RESOLVE_A 1 | |
17 #define NGX_RESOLVE_CNAME 5 | |
18 #define NGX_RESOLVE_PTR 12 | |
19 #define NGX_RESOLVE_MX 15 | |
20 #define NGX_RESOLVE_TXT 16 | |
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21 #if (NGX_HAVE_INET6) |
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22 #define NGX_RESOLVE_AAAA 28 |
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23 #endif |
1965 | 24 #define NGX_RESOLVE_DNAME 39 |
1649 | 25 |
26 #define NGX_RESOLVE_FORMERR 1 | |
27 #define NGX_RESOLVE_SERVFAIL 2 | |
28 #define NGX_RESOLVE_NXDOMAIN 3 | |
29 #define NGX_RESOLVE_NOTIMP 4 | |
30 #define NGX_RESOLVE_REFUSED 5 | |
31 #define NGX_RESOLVE_TIMEDOUT NGX_ETIMEDOUT | |
32 | |
33 | |
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34 #define NGX_NO_RESOLVER (void *) -1 |
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35 |
1969 | 36 #define NGX_RESOLVER_MAX_RECURSION 50 |
37 | |
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38 |
1649 | 39 typedef struct { |
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40 ngx_connection_t *udp; |
1649 | 41 struct sockaddr *sockaddr; |
42 socklen_t socklen; | |
43 ngx_str_t server; | |
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44 ngx_log_t log; |
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45 } ngx_resolver_connection_t; |
1649 | 46 |
47 | |
48 typedef struct ngx_resolver_ctx_s ngx_resolver_ctx_t; | |
49 | |
50 typedef void (*ngx_resolver_handler_pt)(ngx_resolver_ctx_t *ctx); | |
51 | |
52 | |
53 typedef struct { | |
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54 ngx_rbtree_node_t node; |
1649 | 55 ngx_queue_t queue; |
56 | |
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57 /* PTR: resolved name, A: name to resolve */ |
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58 u_char *name; |
1649 | 59 |
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60 #if (NGX_HAVE_INET6) |
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61 /* PTR: IPv6 address to resolve (IPv4 address is in rbtree node key) */ |
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62 struct in6_addr addr6; |
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63 #endif |
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64 |
1649 | 65 u_short nlen; |
66 u_short qlen; | |
67 | |
68 u_char *query; | |
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69 #if (NGX_HAVE_INET6) |
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70 u_char *query6; |
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71 #endif |
1649 | 72 |
73 union { | |
74 in_addr_t addr; | |
75 in_addr_t *addrs; | |
76 u_char *cname; | |
77 } u; | |
78 | |
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79 u_char code; |
1649 | 80 u_short naddrs; |
81 u_short cnlen; | |
82 | |
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83 #if (NGX_HAVE_INET6) |
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84 union { |
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85 struct in6_addr addr6; |
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86 struct in6_addr *addrs6; |
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87 } u6; |
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88 |
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89 u_short naddrs6; |
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90 #endif |
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91 |
1649 | 92 time_t expire; |
93 time_t valid; | |
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94 uint32_t ttl; |
1649 | 95 |
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96 ngx_uint_t last_connection; |
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97 |
1649 | 98 ngx_resolver_ctx_t *waiting; |
99 } ngx_resolver_node_t; | |
100 | |
101 | |
102 typedef struct { | |
103 /* has to be pointer because of "incomplete type" */ | |
104 ngx_event_t *event; | |
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105 void *dummy; |
1649 | 106 ngx_log_t *log; |
107 | |
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108 /* event ident must be after 3 pointers as in ngx_connection_t */ |
1649 | 109 ngx_int_t ident; |
110 | |
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111 /* simple round robin DNS peers balancer */ |
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112 ngx_array_t connections; |
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113 ngx_uint_t last_connection; |
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114 |
1649 | 115 ngx_rbtree_t name_rbtree; |
116 ngx_rbtree_node_t name_sentinel; | |
117 | |
118 ngx_rbtree_t addr_rbtree; | |
119 ngx_rbtree_node_t addr_sentinel; | |
120 | |
121 ngx_queue_t name_resend_queue; | |
122 ngx_queue_t addr_resend_queue; | |
123 | |
124 ngx_queue_t name_expire_queue; | |
125 ngx_queue_t addr_expire_queue; | |
126 | |
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127 #if (NGX_HAVE_INET6) |
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128 ngx_uint_t ipv6; /* unsigned ipv6:1; */ |
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129 ngx_rbtree_t addr6_rbtree; |
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130 ngx_rbtree_node_t addr6_sentinel; |
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131 ngx_queue_t addr6_resend_queue; |
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132 ngx_queue_t addr6_expire_queue; |
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133 #endif |
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134 |
1649 | 135 time_t resend_timeout; |
136 time_t expire; | |
137 time_t valid; | |
138 | |
139 ngx_uint_t log_level; | |
140 } ngx_resolver_t; | |
141 | |
142 | |
143 struct ngx_resolver_ctx_s { | |
144 ngx_resolver_ctx_t *next; | |
145 ngx_resolver_t *resolver; | |
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146 ngx_resolver_node_t *node; |
1649 | 147 |
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148 /* event ident must be after 3 pointers as in ngx_connection_t */ |
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149 ngx_int_t ident; |
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150 |
1649 | 151 ngx_int_t state; |
152 ngx_str_t name; | |
153 | |
154 ngx_uint_t naddrs; | |
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155 ngx_addr_t *addrs; |
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156 ngx_addr_t addr; |
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157 struct sockaddr_in sin; |
1649 | 158 |
159 ngx_resolver_handler_pt handler; | |
160 void *data; | |
161 ngx_msec_t timeout; | |
162 | |
163 ngx_uint_t quick; /* unsigned quick:1; */ | |
1969 | 164 ngx_uint_t recursion; |
1649 | 165 ngx_event_t *event; |
166 }; | |
167 | |
168 | |
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169 ngx_resolver_t *ngx_resolver_create(ngx_conf_t *cf, ngx_str_t *names, |
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170 ngx_uint_t n); |
1649 | 171 ngx_resolver_ctx_t *ngx_resolve_start(ngx_resolver_t *r, |
172 ngx_resolver_ctx_t *temp); | |
173 ngx_int_t ngx_resolve_name(ngx_resolver_ctx_t *ctx); | |
174 void ngx_resolve_name_done(ngx_resolver_ctx_t *ctx); | |
175 ngx_int_t ngx_resolve_addr(ngx_resolver_ctx_t *ctx); | |
176 void ngx_resolve_addr_done(ngx_resolver_ctx_t *ctx); | |
177 char *ngx_resolver_strerror(ngx_int_t err); | |
178 | |
179 | |
180 #endif /* _NGX_RESOLVER_H_INCLUDED_ */ |