Accommodate XCC firmware behavior

It has been observed that a Lenovo XCC can fail to produce the
appropriate attributes in the SLP data.  In such a case, and only if we
are in the preconfig path (which means it is a candidate for discovery),
reset the XCC to try to correct the behavior.

confluent_server/confluent/discovery/core.py

@@ -815,7 +815,12 @@ def eval_node(cfg, handler, info, nodename, manual=False):
         # for now, we search switch only, ideally we search cmm, smm, and
         # switch concurrently
         # do some preconfig, for example, to bring a SMM online if applicable
-        handler.preconfig()
+        errorstr = handler.preconfig()
+        if errorstr:
+            if manual:
+                raise exc.InvalidArgumentException(errorstr)
+            log.log({'error': errorstr})
+            return
     except Exception as e:
         unknown_info[info['hwaddr']] = info
         info['discostatus'] = 'unidentified'

confluent_server/confluent/discovery/handlers/xcc.py

@@ -22,7 +22,24 @@ class NodeHandler(immhandler.NodeHandler):
     devname = 'XCC'
 
     def preconfig(self):
-        ff = self.info.get('attributes', {}).get('enclosure-form-factor', '')
+        ff = None
+        try:
+            ff = self.info['attributes']['enclosure-form-factor']
+        except KeyError:
+            try:
+                # an XCC should always have that set, this is sign of
+                # a bug, try to reset the BMC as a workaround
+                ipmicmd = self._get_ipmicmd()
+                ipmicmd.reset_bmc()
+                return "XCC with address {0} did not have attributes " \
+                       "declared, attempting to correct with " \
+                       "XCC reset".format(self.ipaddr)
+            except pygexc.IpmiException as e:
+                if (e.ipmicode != 193 and
+                        'Unauthorized name' not in str(e) and
+                        'Incorrect password' not in str(e)):
+                # raise an issue if anything other than to be expected
+                raise
         if ff not in ('dense-computing', [u'dense-computing']):
             return
         # attempt to enable SMM