[hostcfgd] hostcfgd will exit when set hostname in DEVICE_METADATA (s…

…onic-net#3394)

Signed-off-by: ouxiaolong <ouxiaolong@asterfusion.com>

files/image_config/hostcfgd/hostcfgd

@@ -24,10 +24,8 @@ TACPLUS_SERVER_TIMEOUT_DEFAULT = "5"
 TACPLUS_SERVER_AUTH_TYPE_DEFAULT = "pap"
 
 
-def is_valid_hostname(name):
-    if hostname[-1] == ".":
-        hostname = hostname[:-1] # strip exactly one dot from the right, if present
-    if len(hostname) > 253:
+def is_valid_hostname(hostname):
+    if hostname[-1] == "." or len(hostname) > 253:
         return False
     allowed = re.compile("(?!-)[A-Z\d-]{1,63}(?<!-)$", re.IGNORECASE)
     return all(allowed.match(x) for x in hostname.split("."))
@@ -267,6 +265,7 @@ class HostConfigDaemon:
             syslog.syslog(syslog.LOG_WARNING, "hostname key is missing")
             return
         if not is_valid_hostname(hostname):
+            syslog.syslog(syslog.LOG_WARNING, "hostname {} is invalid".format(hostname))
             return
         if hostname == self.hostname_cache:
             return