stellar-halting-analysis

Analyze a transitive quorum to find halting weaknesses. Runs through all the nodes and checks for any combination of N failures which can cause your node to halt. This is a more thorough version of the stellar-core /info endpoint's fail-at property, since the built-in version doesn't handle propagation of failures.

The algorithm will return an array of HaltingFailures, which have arrays of vulnerableNodes (the nodes which can go down and take our network with it) and affectedNodes (the nodes which get taken down along the way.

usage

import { haltingAnalysis, NetworkGraphNode } from "@stellar/halting-analysis"

const nodes : NetworkGraphNode[] = await getJSON("http://stellar-core-host:11626/quorum?transitive=true&fullnodes=true"

// Search for any single node which could cause our network to halt if it goes down
const failures : HaltingFailure[] = haltingAnalysis(nodes, 1)

// Search for any combination of up to 3 nodes which could cause our node to halt if they all failed
const failures = haltingAnalysis(nodes, 3)

type definitions

// Represents a failure case where a set of N nodes can take down your network
type HaltingFailure = {
  // The nodes which can go down and cause havoc
  vulnerableNodes: NetworkGraphNode[];
  // The nodes which will go down in response to the vulnerable nodes
  affectedNodes: NetworkGraphNode[];
};

// A QuorumSetGroup can be either a grouping of validators as a single
// quorum set, or a group of inner quorum sets
export type QuorumSet = {
  // Threshold, the number of validators that need to agree
  readonly t: number;
  // List of validators or subquorum sets
  readonly v: (string | QuorumSet)[];
};

export type NetworkGraphNode = {
  // How far that node is from the root node (ie. how many quorum set hops)
  // 0 means this is the node being administrated
  readonly distance: number;
  // The latest ledger sequence number that this node voted at
  readonly heard?: number;
  // The identity of the validator
  readonly node: string;
  // Quorum set.  Missing or unknown nodes will be undefined.
  readonly qset?: QuorumSet;
  // one of behind|tracking|ahead (compared to the root node) or missing|unknown (when there are no recent SCP messages for that node)
  readonly status: "behind" | "tracking" | "ahead" | "missing" | "unknown";
  // what the node is voting for
  readonly value?: string;
  // a unique ID for what the node is voting for (allows to quickly tell if nodes are voting for the same thing)
  readonly value_id?: number;
};