XXX-DIRTY: dns: support port for a nameserver

XXX-DIRTY:
 * it's unknown how nameservers shall be defined in surykatka, thus urlparse was used,
   to have it available like 127.0.0.1:5353 or [::1]:5454

src/surykatka/dns.py

@@ -17,6 +17,7 @@
 # See COPYING file for full licensing terms.
 # See https://www.nexedi.com/licensing for rationale and options.
 
+import urllib
 from dns import (
     resolver as dns_resolver,
     name as dns_name,
@@ -96,7 +97,9 @@ def logDnsQuery(db, status_id, resolver_ip, domain_text, rdtype, answer_list):
 
 def buildResolver(resolver_ip, timeout):
     resolver = dns_resolver.Resolver(configure=False)
-    resolver.nameservers.append(resolver_ip)
+    resolver_ip_parsed = urllib.parse.urlparse('dns://' + resolver_ip)
+    resolver.nameservers.append(resolver_ip_parsed.hostname)
+    resolver.nameserver_ports[ip] = resolver_ip_parsed.port
     resolver.timeout = timeout
     resolver.lifetime = timeout
     resolver.edns = -1