cares: fix missing lazy init for CURLOPT_DNS_SERVERS

When setting option CURLOPT_DNS_SERVERS, the ares channel was not
properly initialized and the setting failed.

Fixes #17119
Reported-by: calvin2021y on github
Closes #17127

diff --git a/lib/asyn-ares.c b/lib/asyn-ares.c
index 80efeeb37c0d78f5e3c85cf301cb85c504fb818a..147b4a743e8221100eef0e81d0bdbff12486751f 100644 (file)
--- a/lib/asyn-ares.c
+++ b/lib/asyn-ares.c
@@ -816,6 +816,10 @@ CURLcode Curl_set_dns_servers(struct Curl_easy *data,
   }
 
 #ifdef HAVE_CARES_SERVERS_CSV
+  result = async_ares_init_lazy(data);
+  if(result)
+    return result;
+
 #ifdef HAVE_CARES_PORTS_CSV
   ares_result = ares_set_servers_ports_csv(ares->channel, servers);
 #else