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comparison src/core/ngx_resolver.c @ 7312:54683f650cbd

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Resolver: retry sending queries on errors (ticket #1511). Errors when sending UDP datagrams can happen, e.g., when local IP address changes (see fa0e093b64d7), or an unavailable DNS server on the LAN can cause send() to fail with EHOSTDOWN on BSD systems. If this happens during initial query, retry sending immediately, to a different DNS server when possible. If this is not enough, allow normal resend to happen by ignoring the return code of the second ngx_resolver_send_query() call, much like we do in ngx_resolver_resend().
author Maxim Dounin <mdounin@mdounin.ru>
date Thu, 05 Jul 2018 22:21:14 +0300
parents faf14dc9ab4d
children cbc5dee8d5d2
comparison
equal deleted inserted replaced
7311:778358452a81 7312:54683f650cbd
845 rn->tcp6 = 0; 845 rn->tcp6 = 0;
846 #endif 846 #endif
847 rn->nsrvs = 0; 847 rn->nsrvs = 0;
848 848
849 if (ngx_resolver_send_query(r, rn) != NGX_OK) { 849 if (ngx_resolver_send_query(r, rn) != NGX_OK) {
850 goto failed; 850
851 /* immediately retry once on failure */
852
853 rn->last_connection++;
854 if (rn->last_connection == r->connections.nelts) {
855 rn->last_connection = 0;
856 }
857
858 (void) ngx_resolver_send_query(r, rn);
851 } 859 }
852 860
853 if (ngx_resolver_set_timeout(r, ctx) != NGX_OK) { 861 if (ngx_resolver_set_timeout(r, ctx) != NGX_OK) {
854 goto failed; 862 goto failed;
855 } 863 }
1049 rn->tcp6 = 0; 1057 rn->tcp6 = 0;
1050 #endif 1058 #endif
1051 rn->nsrvs = 0; 1059 rn->nsrvs = 0;
1052 1060
1053 if (ngx_resolver_send_query(r, rn) != NGX_OK) { 1061 if (ngx_resolver_send_query(r, rn) != NGX_OK) {
1054 goto failed; 1062
1063 /* immediately retry once on failure */
1064
1065 rn->last_connection++;
1066 if (rn->last_connection == r->connections.nelts) {
1067 rn->last_connection = 0;
1068 }
1069
1070 (void) ngx_resolver_send_query(r, rn);
1055 } 1071 }
1056 1072
1057 if (ngx_resolver_set_timeout(r, ctx) != NGX_OK) { 1073 if (ngx_resolver_set_timeout(r, ctx) != NGX_OK) {
1058 goto failed; 1074 goto failed;
1059 } 1075 }