dns.resolver.query treats hostnames as relative names if they don't end in a period

Relative hostnames have a fall-back lookup with the machine's hostname appended, which makes no sense. Add a period, e.g. "my.hostname.com" => "my.hostname.com.", to prevent that.

This caused false positive Spamhaus checks. Fixes #185.

management/dns_update.py

@@ -490,7 +490,7 @@ zone:
 			# Get the IP address of the nameserver by resolving it.
 			hostname = additional_records.get("_secondary_nameserver")
 			resolver = dns.resolver.get_default_resolver()
-			response = dns.resolver.query(hostname, "A")
+			response = dns.resolver.query(hostname+'.', "A")
 			ipaddr = str(response[0])
 			nsdconf += """\tnotify: %s NOKEY
 	provide-xfr: %s NOKEY

management/status_checks.py

@@ -347,7 +347,15 @@ def check_web_domain(domain, env):
 	check_ssl_cert(domain, env)
 
 def query_dns(qname, rtype, nxdomain='[Not Set]'):
-	resolver = dns.resolver.get_default_resolver()
+	# Make the qname absolute by appending a period. Without this, dns.resolver.query
+	# will fall back a failed lookup to a second query with this machine's hostname
+	# appended. This has been causing some false-positive Spamhaus reports. The
+	# reverse DNS lookup will pass a dns.name.Name instance which is already
+	# absolute so we should not modify that.
+	if isinstance(qname, str):
+		qname += "."
+
+	# Do the query.
 	try:
 		response = dns.resolver.query(qname, rtype)
 	except (dns.resolver.NoNameservers, dns.resolver.NXDOMAIN, dns.resolver.NoAnswer):