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564 lines
17 KiB
564 lines
17 KiB
import {Inject, Singleton} from "@extollo/di"
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import {Application, Config, Logging, Unit} from "@extollo/lib"
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import {FirebaseUnit} from "./FirebaseUnit"
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import {
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BlockEncounterTransaction,
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BlockResourceItem,
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BlockTransaction,
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isBlockResourceItem
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} from "../rtdb/BlockResource"
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import {TransactionResourceItem} from "../rtdb/TransactionResource"
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import * as openpgp from "openpgp"
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import * as crypto from "crypto"
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import fetch from "node-fetch"
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import {collect, uuid_v4} from "@extollo/util"
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import {ExposureResourceItem} from "../rtdb/ExposureResource"
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/**
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* Verify an OpenPGP signature based on an armored key.
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* @param armoredKey
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* @param armoredMessage
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*/
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async function pgpVerify(armoredKey: string, armoredMessage: string) {
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const [publicKeys, message] = await Promise.all([
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openpgp.readKey({ armoredKey }),
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openpgp.readMessage({ armoredMessage })
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])
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return !!(await (await openpgp.verify({ publicKeys, message })).signatures?.[0]?.verified)
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}
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/**
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* Utility wrapper class for a block in the chain.
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*/
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export class Block implements BlockResourceItem {
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uuid: string
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transactions: BlockTransaction[]
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timestamp: number
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lastBlockHash: string
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lastBlockUUID: string
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proof: string
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waitTime: number
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peer: string
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get config(): Config {
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return Application.getApplication().make(Config)
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}
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constructor(rec: BlockResourceItem) {
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this.uuid = rec.uuid || uuid_v4()
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this.transactions = rec.transactions || []
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this.lastBlockHash = rec.lastBlockHash || ''
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this.lastBlockUUID = rec.lastBlockUUID || ''
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this.proof = rec.proof
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this.timestamp = rec.timestamp || (new Date).getTime()
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this.waitTime = rec.waitTime
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this.peer = rec.peer
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}
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/** Returns true if this is the genesis block. */
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async isGenesis() {
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// first block will be guaranteed uuid 0000
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if (this.uuid !== '0000') {
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return false
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}
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const proof = this.proof
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const publicKey = this.config.get("app.gpg.key.public")
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return pgpVerify(publicKey, proof)
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}
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/** Generate the hash for this block. */
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hash() {
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return crypto.createHash('sha256')
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.update(this.toString(), 'utf-8')
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.digest('hex')
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}
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/** Cast the Block's data to a plain object. */
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toItem(): BlockResourceItem {
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return {
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uuid: this.uuid,
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transactions: this.transactions,
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lastBlockHash: this.lastBlockHash,
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lastBlockUUID: this.lastBlockUUID,
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proof: this.proof,
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timestamp: this.timestamp,
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waitTime: this.waitTime,
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peer: this.peer,
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}
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}
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/** Generate the deterministic hash-able string. */
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toString() {
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return [
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this.uuid,
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this.waitTime,
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JSON.stringify(this.transactions || [], undefined, 0),
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this.lastBlockHash,
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this.lastBlockUUID,
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].join('%')
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}
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}
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/**
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* Interface representing a federated peer.
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*/
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export interface Peer {
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host: string,
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name?: string,
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}
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/**
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* Blockchain Unit
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* ---------------------------------------
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* Main service for interacting with the contact blockchain.
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*/
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@Singleton()
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export class Blockchain extends Unit {
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private readonly MIN_WAIT_TIME = 10000
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private readonly MAX_WAIT_TIME = 30000
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private readonly PENALTY_INTERVAL = 5000
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private readonly MAX_PEERS_PENALTY = 10
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@Inject()
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protected readonly logging!: Logging
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@Inject()
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protected readonly firebase!: FirebaseUnit
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@Inject()
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protected readonly config!: Config
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/** The most-correct, approved chain according to this node. */
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protected approvedChain: Block[] = []
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/** The peers this node will communicate with. */
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protected peers: Peer[] = []
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/** If true, the writeback/refresh cycle will stop. */
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protected breakForExit = false
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/**
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* Block transactions that will be attempted as part of this host's
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* next block submission.
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* @protected
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*/
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protected pendingTransactions: BlockTransaction[] = []
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protected publicKey!: openpgp.Key
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protected privateKey!: openpgp.Key
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protected genesisProof!: string
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protected nextWaitTime!: number
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protected lastBlock!: Block
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protected nextProof!: string
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async up() {
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this.logging.info('Generating OpenPGP assets...')
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this.publicKey = await openpgp.readKey({
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armoredKey: this.config.get("app.gpg.key.public")
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})
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this.privateKey = await openpgp.readKey({
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armoredKey: this.config.get("app.gpg.key.private")
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})
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this.genesisProof = await openpgp.sign({
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message: openpgp.Message.fromText('0000'),
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privateKeys: this.privateKey,
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})
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this.logging.info('Performing initial load...')
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await this.initialLoad()
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this.logging.info('Contacting configured peers...')
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const peers = this.config.get('server.peers')
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await Promise.all(peers.map((host: string) => this.registerPeer({ host })))
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this.logging.info('Performing initial writeback...')
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await this.writeback()
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}
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async down() {
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this.breakForExit = true
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}
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/** Load the initial data from the data sources into memory for fast access. */
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async initialLoad() {
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const [peers, chain] = await Promise.all([
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this.firebase.ref('peers')
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.once('value')
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.then(val => val.val()),
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this.firebase.ref('block')
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.orderByKey()
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.once('value')
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.then(val => val.val())
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])
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this.logging.debug({peers, chain})
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this.approvedChain = (chain || []).map((item: BlockResourceItem) => new Block(item))
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this.peers = peers || []
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}
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/**
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* Returns true if the given host is registered as a peer.
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* @param host
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*/
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public hasPeer(host: string): boolean {
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return this.peers.some(x => x.host === host)
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}
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/**
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* Get a list of all registered peers.
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*/
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public getPeers(): Peer[] {
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return this.peers
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}
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/**
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* From a peer, fetch the submission blockchain, if it is valid.
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* @param peer
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*/
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public async getPeerSubmit(peer: Peer): Promise<Block[] | undefined> {
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try {
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const result = await fetch(`${peer.host}api/v1/chain/submit`).then(res => res.json())
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const blocks: unknown = result.data?.data?.records
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if ( Array.isArray(blocks) && blocks.every(block => {
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return isBlockResourceItem(block)
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}) ) {
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return blocks.map(x => new Block(x))
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}
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} catch (e) {
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this.logging.error(e)
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return undefined
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}
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}
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/**
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* Register a new host as a peer of this instance.
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* @param peer
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*/
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public async registerPeer(peer: Peer) {
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if ( !this.hasPeer(peer.host) ) {
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this.logging.info(`Registering peer: ${peer.host}`)
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const header = this.config.get('app.api_server_header')
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this.peers.push(peer)
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try {
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await fetch(`${peer.host}api/v1/peer`, {
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method: 'POST',
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body: JSON.stringify({
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host: this.getBaseURL(),
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}),
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headers: {
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'content-type': 'application/json',
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},
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})
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} catch (e) {
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this.logging.error(e)
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}
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}
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}
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/**
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* Given an array of blocks in chain-order, validate the chain.
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* @param chain
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* @return boolean - true if the chain is valid
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*/
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public async validate(chain: Block[]) {
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const blocks = collect<Block>(chain)
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return (
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await blocks.promiseMap(async (block, idx) => {
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if ( await block.isGenesis() ) {
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return true
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}
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const previous: Block | undefined = blocks.at(idx - 1)
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if ( !previous ) {
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this.logging.debug(`Chain is invalid: block ${idx} is missing previous ${idx - 1}.`)
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return false;
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}
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const pass = (
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block.lastBlockUUID === previous.uuid
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&& block.lastBlockHash === previous.hash()
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)
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if ( !pass ) {
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this.logging.debug(`Chain is invalid: block ${idx} does not match previous.`)
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this.logging.debug({
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lastBlockUUID: block.lastBlockUUID,
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computedLastUUID: previous.uuid,
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lastBlockHash: block.lastBlockHash,
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computedLastHash: previous.hash(),
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})
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return false
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}
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if ( !(await this.validateProofOfWork(block, previous)) ) {
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this.logging.debug(`Chain is invalid: block ${idx} failed proof of work validation`)
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return false;
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}
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return false
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})
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).every(Boolean)
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}
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/**
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* Perform the consensus algorithm among the peers of this node
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* to push a block onto the chain.
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*/
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public async refresh() {
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if ( this.breakForExit ) return;
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this.logging.debug('Called refresh().')
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const peers = this.getPeers()
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let longestChain: Block[] = []
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const chains = await Promise.all(
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peers.map(peer => this.getPeerSubmit(peer))
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)
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for ( const chain of chains ) {
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if (
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chain
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&& chain.length > longestChain.length
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&& await this.validate(chain)
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) {
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longestChain = chain
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}
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}
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const submitted = this.getSubmitBlock()
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if ( (this.approvedChain.length + (submitted ? 1 : 0)) > longestChain.length ) {
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// Our chain is longer, so push the submit block onto it
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if ( submitted ) {
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this.approvedChain.push(submitted)
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this.pendingTransactions = []
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}
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} else {
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const temp: Block[] = this.approvedChain.reverse()
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this.approvedChain = longestChain.map(x => {
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if ( !x.transactions ) {
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x.transactions = []
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}
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return x
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})
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for ( const block of temp ) {
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const found = this.approvedChain.some(otherBlock => {
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return otherBlock.uuid === block.uuid
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})
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if ( !found ) {
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this.pendingTransactions.concat(...(block.transactions || []))
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} else {
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break
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}
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}
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}
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console.log('approved chain', this.approvedChain)
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await this.writeback()
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}
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/**
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* Get the current blockchain including the block submitted by this node.
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*/
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public getSubmitChain(): BlockResourceItem[] {
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const submit = this.getSubmitBlock()
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if ( !submit ) return this.approvedChain
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else return [...this.approvedChain, submit]
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}
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/**
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* Write the in-memory data back to persistent data stores.
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*/
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public async writeback() {
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if ( this.breakForExit ) return;
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this.nextWaitTime = this.random(this.MIN_WAIT_TIME, this.MAX_WAIT_TIME)
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this.lastBlock = this.getLastBlock()
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this.nextProof = await this.generateProofOfWork(this.lastBlock, this.nextWaitTime)
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await Promise.all([
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this.firebase.ref('block').set(this.approvedChain.map(x => x.toItem())),
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this.firebase.ref('peers').set(this.peers)
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])
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this.refresh()
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}
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/**
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* Get the Block instance that we want to submit to the chain, if we have any transactions.
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*/
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public getSubmitBlock(): Block | undefined {
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if ( !this.pendingTransactions?.length ) {
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return
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}
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return new Block({
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timestamp: (new Date).getTime(),
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uuid: uuid_v4(),
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transactions: this.pendingTransactions,
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lastBlockHash: this.lastBlock.hash(),
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lastBlockUUID: this.lastBlock.uuid,
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proof: this.nextProof,
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waitTime: this.nextWaitTime,
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peer: this.getBaseURL(),
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})
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}
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/**
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* Submit a group of encounter transactions to be added to the chain.
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* @param groups
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*/
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public submitTransactions(...groups: [TransactionResourceItem, TransactionResourceItem][]) {
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groups.forEach(group => {
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const txes = group.map(item => this.getEncounterTransaction(item))
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this.pendingTransactions.push(...txes)
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})
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}
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/**
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* Submit the given exposure notifications onto the blockchain.
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* @param exposures
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*/
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public submitExposures(...exposures: ExposureResourceItem[]) {
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// @ts-ignore
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this.pendingTransactions.push(...exposures.map(exposure => {
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if ( !exposure.uuid ) {
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exposure.uuid = uuid_v4()
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}
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return exposure
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}))
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}
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/**
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* Get the peer-to-peer identifier token.
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*/
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public getPeerToken() {
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return Buffer.from(this.genesisProof, 'utf-8')
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.toString('base64')
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}
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/**
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* Instantiate the genesis block of the entire chain.
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*/
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public getGenesisBlock(): Block {
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return new Block({
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timestamp: (new Date).getTime(),
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uuid: '0000',
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transactions: [],
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lastBlockHash: '',
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lastBlockUUID: '',
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proof: this.genesisProof,
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firebaseID: '',
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waitTime: 0,
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peer: this.getBaseURL(),
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})
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}
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/**
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* Get the last block in the blockchain, or push the genesis if one doesn't already exist.
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*/
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public getLastBlock(): Block {
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if ( !this.approvedChain ) {
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this.approvedChain = []
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}
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const rec = this.approvedChain.slice(-1)[0]
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if (rec) return rec
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const genesis = this.getGenesisBlock()
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this.approvedChain.push(genesis)
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return genesis
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}
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/**
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* Get a list of all blocks in the chain, in order.
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*/
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public read(): Promise<BlockResourceItem[]> {
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return this.firebase.ref('block')
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.once('value')
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.then(snap => snap.val())
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}
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/**
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* Given a client-submitted transaction, generate a block encounter transaction record.
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* @param item
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* @protected
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*/
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protected getEncounterTransaction(item: TransactionResourceItem): BlockEncounterTransaction {
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return {
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uuid: uuid_v4(),
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combinedHash: item.combinedHash,
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timestamp: item.timestamp,
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encodedGPSLocation: item.encodedGPSLocation,
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}
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}
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/**
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* Generate a proof of work string for the block that follows lastBlock.
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* @param lastBlock
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* @param waitTime
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* @protected
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*/
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protected async generateProofOfWork(lastBlock: Block, waitTime: number): Promise<string> {
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const hashString = lastBlock.hash()
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const message = openpgp.Message.fromText(hashString)
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await this.sleep(waitTime)
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// Sign the hash using the server's private key
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return openpgp.sign({
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message,
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privateKeys: this.privateKey,
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})
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}
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/**
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* Validate that the proof of work of currentBlock is accurate relative to lastBlock.
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* @param currentBlock
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* @param lastBlock
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* @protected
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*/
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protected validateProofOfWork(currentBlock: Block, lastBlock: Block): Promise<boolean> {
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const proof = lastBlock.proof
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const publicKey = this.config.get("app.gpg.key.public")
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return pgpVerify(publicKey, proof)
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}
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/**
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* Get the base URL that identifies this peer.
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* This should be the endpoint used to fetch the submitted blockchain.
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* @protected
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*/
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protected getBaseURL(): string {
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const base = this.config.get('server.base_url')
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return `${base}${base.endsWith('/') ? '' : '/'}`
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}
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/** Sleep for (roughly) the given number of milliseconds. */
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async sleep(ms: number) {
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await new Promise<void>(res => {
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setTimeout(res, ms)
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})
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}
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/**
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* Get a random number between two values.
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* @param min
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* @param max
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*/
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random(min: number, max: number): number {
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return Math.floor(Math.random() * (Math.floor(max) - Math.ceil(min) + 1)) + Math.ceil(min);
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}
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}
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