Added option --no-reverse to add-host

When adding a host with specific IP address, the operation would fail in
case IPA doesn't own the reverse DNS. This new option overrides the
check for reverse DNS zone and falls back to different IP address
existence check.

https://fedorahosted.org/freeipa/ticket/417

ipalib/plugins/host.py

@@ -260,6 +260,9 @@ class host_add(LDAPCreate):
         Flag('force',
             doc=_('force host name even if not in DNS'),
         ),
+        Flag('no_reverse',
+            doc=_('skip reverse DNS detection'),
+        ),
         Str('ipaddr?', validate_ipaddr,
             doc=_('Add the host to DNS with this IP address'),
         ),
@@ -277,6 +280,8 @@ class host_add(LDAPCreate):
                     break
             if not match:
                 raise errors.NotFound(reason=_('DNS zone %(zone)s not found' % dict(zone=domain)))
+            if not options.get('no_reverse',False):
+                # we prefer lookup of the IP through the reverse zone
                 revzone, revname = get_reverse_zone(options['ipaddr'])
                 # Verify that our reverse zone exists
                 match = False
@@ -292,6 +297,10 @@ class host_add(LDAPCreate):
                         raise errors.DuplicateEntry(message=u'This IP address is already assigned.')
                 except errors.NotFound:
                     pass
+            else:
+                result = api.Command['dnsrecord_find'](domain, arecord=options['ipaddr'])
+                if result['count'] > 0:
+                    raise errors.DuplicateEntry(message=u'This IP address is already assigned.')
         if not options.get('force', False) and not 'ipaddr' in options:
             util.validate_host_dns(self.log, keys[-1])
         if 'locality' in entry_attrs: