unwind(8): give the first available resolver strategy a bit more time

[Florian Obser]

unwind(8) gives the most preferred resolver strategy a bit more time
(200ms) to answer before trying the next strategy. However, we need to
skip strategies that are not available. In the default configuration,
without a config file, unwind(8) would give DoT 200ms more time, but no
DoT forwarders are known, so this is useless.

OK?

diff --git resolver.c resolver.c
index 81485b230fa..1eb505512e4 100644
--- resolver.c
+++ resolver.c
@@ -772,6 +772,7 @@ try_next_resolver(struct running_query *rq)
        struct timespec          tp, elapsed;
        struct timeval           tv = {0, 0};
        int64_t                  ms;
+       int                      i;
 
        while(rq->next_resolver < rq->res_pref.len &&
            ((res = resolvers[rq->res_pref.types[rq->next_resolver]]) == NULL ||
@@ -804,7 +805,12 @@ try_next_resolver(struct running_query *rq)
        ms = res->median;
        if (ms > NEXT_RES_MAX)
                ms = NEXT_RES_MAX;
-       if (res->type == resolver_conf->res_pref.types[0])
+
+       /* skip over unavailable resolvers in preferences */
+       for (i = 0; i < resolver_conf->res_pref.len &&
+                resolvers[resolver_conf->res_pref.types[i]] == NULL; i++)
+               ;
+       if (res->type == resolver_conf->res_pref.types[i])
                tv.tv_usec = 1000 * (PREF_RESOLVER_MEDIAN_SKEW + ms);
        else
                tv.tv_usec = 1000 * ms;

-- 
I'm not entirely sure you are real.