host: try to resolve FQDN before command execution

Trying to resolve the FQDN before command execution (during
pre-callback) helps detect cases where the host specified by the user
does not exist, saving execution time. Aside from this, resolving the
FQDN is useful when only the shortname of the host is passed, as this
would cause issues when trying to update the DNS records during
modification of the entry.

Fixes: https://pagure.io/freeipa/issue/8726
Fixes: https://pagure.io/freeipa/issue/8884
Signed-off-by: Antonio Torres <antorres@redhat.com>
Reviewed-By: Rob Crittenden <rcritten@redhat.com>

ipaserver/plugins/host.py

@@ -252,6 +252,11 @@ def validate_ipaddr(ugettext, ipaddr):
     return None
 
 
+def resolve_fqdn(name):
+    hostentry = api.Command['host_show'](name)['result']
+    return hostentry['fqdn'][0]
+
+
 class HostPassword(Str):
     """
     A data type for host passwords to not log password values
@@ -795,14 +800,7 @@ class host_del(LDAPDelete):
 
     def pre_callback(self, ldap, dn, *keys, **options):
         assert isinstance(dn, DN)
-        # If we aren't given a fqdn, find it
-        config = ldap.get_ipa_config()
-        maxlen = int(config.get('ipamaxhostnamelength')[0])
-        if hostname_validator(None, keys[-1], maxlen=maxlen) is not None:
-            hostentry = api.Command['host_show'](keys[-1])['result']
-            fqdn = hostentry['fqdn'][0]
-        else:
-            fqdn = keys[-1]
+        fqdn = resolve_fqdn(keys[-1])
         host_is_master(ldap, fqdn)
         # Remove all service records for this host
         truncated = True
@@ -894,6 +892,7 @@ class host_mod(LDAPUpdate):
 
     def pre_callback(self, ldap, dn, entry_attrs, attrs_list, *keys, **options):
         assert isinstance(dn, DN)
+        fqdn = resolve_fqdn(keys[-1])
         # Allow an existing OTP to be reset but don't allow a OTP to be
         # added to an enrolled host.
         if options.get('userpassword') or options.get('random'):
@@ -959,7 +958,7 @@ class host_mod(LDAPUpdate):
                 entry_attrs['objectclass'] = obj_classes
 
         if options.get('updatedns', False) and dns_container_exists(ldap):
-            parts = keys[-1].split('.')
+            parts = fqdn.split('.')
             domain = unicode('.'.join(parts[1:]))
             try:
                 result = api.Command['dnszone_show'](domain)['result']
@@ -1190,13 +1189,7 @@ class host_disable(LDAPQuery):
     def execute(self, *keys, **options):
         ldap = self.obj.backend
 
-        # If we aren't given a fqdn, find it
-        if hostname_validator(None, keys[-1]) is not None:
-            hostentry = api.Command['host_show'](keys[-1])['result']
-            fqdn = hostentry['fqdn'][0]
-        else:
-            fqdn = keys[-1]
-
+        fqdn = resolve_fqdn(keys[-1])
         host_is_master(ldap, fqdn)
 
         # See if we actually do anthing here, and if not raise an exception