Mercurial > hg > nginx
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 |
|---|---|
| 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_ */ |