[nginx] Resolver: report SRV resolve failure if all A resolves failed.

[Roman Arutyunyan]

details:   https://hg.nginx.org/nginx/rev/cbc5dee8d5d2
branches:  
changeset: 7428:cbc5dee8d5d2
user:      Roman Arutyunyan <arut at nginx.com>
date:      Tue Dec 11 19:41:22 2018 +0300
description:
Resolver: report SRV resolve failure if all A resolves failed.

Previously, if an SRV record was successfully resolved, but all of its A
records failed to resolve, NXDOMAIN was returned to the caller, which is
considered a successful resolve rather than an error.  This could result in
losing the result of a previous successful resolve by the caller.

Now NXDOMAIN is only returned if at least one A resolve completed with this
code.  Otherwise the error state of the first A resolve is returned.

diffstat:

 src/core/ngx_resolver.c |  10 +++++++++-
 1 files changed, 9 insertions(+), 1 deletions(-)

diffs (20 lines):

diff -r 81d49f85afed -r cbc5dee8d5d2 src/core/ngx_resolver.c
--- a/src/core/ngx_resolver.c	Tue Dec 11 13:09:00 2018 +0300
+++ b/src/core/ngx_resolver.c	Tue Dec 11 19:41:22 2018 +0300
@@ -4266,7 +4266,15 @@ ngx_resolver_report_srv(ngx_resolver_t *
     }
 
     if (naddrs == 0) {
-        ctx->state = NGX_RESOLVE_NXDOMAIN;
+        ctx->state = srvs[0].state;
+
+        for (i = 0; i < nsrvs; i++) {
+            if (srvs[i].state == NGX_RESOLVE_NXDOMAIN) {
+                ctx->state = NGX_RESOLVE_NXDOMAIN;
+                break;
+            }
+        }
+
         ctx->valid = ngx_time() + (r->valid ? r->valid : 10);
 
         ctx->handler(ctx);