private ClusterState handleJoinRequest(final DiscoveryNode node) {
    if (!master) {
      throw new ElasticsearchIllegalStateException(
          "Node [" + localNode + "] not master for join request from [" + node + "]");
    }

    ClusterState state = clusterService.state();
    if (!transportService.addressSupported(node.address().getClass())) {
      // TODO, what should we do now? Maybe inform that node that its crap?
      logger.warn("received a wrong address type from [{}], ignoring...", node);
    } else {
      // try and connect to the node, if it fails, we can raise an exception back to the client...
      transportService.connectToNode(node);
      state = clusterService.state();

      // validate the join request, will throw a failure if it fails, which will get back to the
      // node calling the join request
      membership.sendValidateJoinRequestBlocking(node, state, pingTimeout);

      clusterService.submitStateUpdateTask(
          "zen-disco-receive(join from node[" + node + "])",
          Priority.URGENT,
          new ClusterStateUpdateTask() {
            @Override
            public ClusterState execute(ClusterState currentState) {
              if (currentState.nodes().nodeExists(node.id())) {
                // the node already exists in the cluster
                logger.warn("received a join request for an existing node [{}]", node);
                // still send a new cluster state, so it will be re published and possibly update
                // the other node
                return ClusterState.builder(currentState).build();
              }
              DiscoveryNodes.Builder builder = DiscoveryNodes.builder(currentState.nodes());
              for (DiscoveryNode existingNode : currentState.nodes()) {
                if (node.address().equals(existingNode.address())) {
                  builder.remove(existingNode.id());
                  logger.warn(
                      "received join request from node [{}], but found existing node {} with same address, removing existing node",
                      node,
                      existingNode);
                }
              }
              latestDiscoNodes = builder.build();
              // add the new node now (will update latestDiscoNodes on publish)
              return ClusterState.builder(currentState)
                  .nodes(latestDiscoNodes.newNode(node))
                  .build();
            }

            @Override
            public void onFailure(String source, Throwable t) {
              logger.error("unexpected failure during [{}]", t, source);
            }
          });
    }
    return state;
  }
  private void innerJoinCluster() {
    boolean retry = true;
    while (retry) {
      if (lifecycle.stoppedOrClosed()) {
        return;
      }
      retry = false;
      DiscoveryNode masterNode = findMaster();
      if (masterNode == null) {
        logger.trace("no masterNode returned");
        retry = true;
        continue;
      }
      if (localNode.equals(masterNode)) {
        this.master = true;
        nodesFD.start(); // start the nodes FD
        clusterService.submitStateUpdateTask(
            "zen-disco-join (elected_as_master)",
            Priority.URGENT,
            new ProcessedClusterStateUpdateTask() {
              @Override
              public ClusterState execute(ClusterState currentState) {
                DiscoveryNodes.Builder builder =
                    new DiscoveryNodes.Builder()
                        .localNodeId(localNode.id())
                        .masterNodeId(localNode.id())
                        // put our local node
                        .put(localNode);
                // update the fact that we are the master...
                latestDiscoNodes = builder.build();
                ClusterBlocks clusterBlocks =
                    ClusterBlocks.builder()
                        .blocks(currentState.blocks())
                        .removeGlobalBlock(NO_MASTER_BLOCK)
                        .build();
                return ClusterState.builder(currentState)
                    .nodes(latestDiscoNodes)
                    .blocks(clusterBlocks)
                    .build();
              }

              @Override
              public void onFailure(String source, Throwable t) {
                logger.error("unexpected failure during [{}]", t, source);
              }

              @Override
              public void clusterStateProcessed(
                  String source, ClusterState oldState, ClusterState newState) {
                sendInitialStateEventIfNeeded();
              }
            });
      } else {
        this.master = false;
        try {
          // first, make sure we can connect to the master
          transportService.connectToNode(masterNode);
        } catch (Exception e) {
          logger.warn("failed to connect to master [{}], retrying...", e, masterNode);
          retry = true;
          continue;
        }
        // send join request
        try {
          membership.sendJoinRequestBlocking(masterNode, localNode, pingTimeout);
        } catch (Exception e) {
          if (e instanceof ElasticsearchException) {
            logger.info(
                "failed to send join request to master [{}], reason [{}]",
                masterNode,
                ((ElasticsearchException) e).getDetailedMessage());
          } else {
            logger.info(
                "failed to send join request to master [{}], reason [{}]",
                masterNode,
                e.getMessage());
          }
          if (logger.isTraceEnabled()) {
            logger.trace("detailed failed reason", e);
          }
          // failed to send the join request, retry
          retry = true;
          continue;
        }
        masterFD.start(masterNode, "initial_join");
        // no need to submit the received cluster state, we will get it from the master when it
        // publishes
        // the fact that we joined
      }
    }
  }