code review and ChangeLog entry

ChangeLog

@@ -69,6 +69,8 @@ TODO: implementing of options resp. other tasks from PR #1346
   - `<ip-rev>` - PTR reversed representation of IP address
   - `<ip-host>` - host name of the IP address
   - `<F-...>` - interpolates to the corresponding filter group capture `...`
+  - `<fq-hostname>` - fully-qualified name of host (the same as `$(hostname -f)`)
+  - `<sh-hostname>` - short hostname (the same as `$(uname -n)`)
 * Allow to use filter options by `fail2ban-regex`, example:
   fail2ban-regex text.log "sshd[mode=aggressive]"
 * Samples test case factory extended with filter options - dict in JSON to control 

fail2ban/server/ipdns.py

@@ -148,11 +148,8 @@ class DNSUtils:
 		# get it using different ways (a set with names of localhost, hostname, fully qualified):
 		if names is None:
 			names = set(['localhost'])
-			for hostname in (socket.gethostname, socket.getfqdn):
-				try:
-					names |= set([hostname()])
-				except Exception as e: # pragma: no cover
-					logSys.warning("Retrieving own hostnames failed: %s", e)
+			for fqdn in (False, True):
+				names.add(DNSUtils.getHostname(fqdn=fqdn))
 		# cache and return :
 		DNSUtils.CACHE_ipToName.set(key, names)
 		return names