从零开始用nodejs写一个区块链 原

npm init

npm install body-parser --save
npm install crypto-js --save
npm install express --save
npm install ws --save

{
  "name": "blockchain",
  "version": "1.0.0",
  "description": "",
  "main": "main.js",
  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1",
    "start": "node main.js"
  },
  "author": "",
  "license": "ISC",
  "dependencies": {
    "express": "^4.16.3",
    "body-parser": "^1.18.3",
    "crypto-js": "^3.1.9-1",
    "ws": "^5.2.0"
  }
}

'use strict';
var CryptoJS = require("crypto-js");
var express = require("express");
var bodyParser = require('body-parser');
var WebSocket = require("ws");

var http_port = process.env.HTTP_PORT || 3001;
var p2p_port = process.env.P2P_PORT || 6001;
var initialPeers = process.env.PEERS ? process.env.PEERS.split(',') : [];

class Block {
  constructor(index, previousHash, timestamp, data, hash) {
    this.index = index;
    this.previousHash = previousHash.toString();
    this.timestamp = timestamp;
    this.data = data;
    this.hash = hash.toString();
  }
}

var sockets = [];
var MessageType = {
  QUERY_LATEST: 0,
  QUERY_ALL: 1,
  RESPONSE_BLOCKCHAIN: 2
};

var getGenesisBlock = () => {
  return new Block(0, "0", 1465154705, "my genesis block!!", "816534932c2b7154836da6afc367695e6337db8a921823784c14378abed4f7d7");
};

var blockchain = [getGenesisBlock()];

var initHttpServer = () => {
  var app = express();
  app.use(bodyParser.json());

  app.get('/blocks', (req, res) => res.send(JSON.stringify(blockchain)));
  app.post('/mineBlock', (req, res) => {
    var newBlock = generateNextBlock(req.body.data);
    addBlock(newBlock);
    broadcast(responseLatestMsg());
    console.log('block added: ' + JSON.stringify(newBlock));
    res.send();
  });
  app.get('/peers', (req, res) => {
    res.send(sockets.map(s => s._socket.remoteAddress + ':' + s._socket.remotePort));
  });
  app.post('/addPeer', (req, res) => {
    connectToPeers([req.body.peer]);
    res.send();
  });
  app.listen(http_port, () => console.log('Listening http on port: ' + http_port));
};


var initP2PServer = () => {
  var server = new WebSocket.Server({ port: p2p_port });
  server.on('connection', ws => initConnection(ws));
  console.log('listening websocket p2p port on: ' + p2p_port);

};

var initConnection = (ws) => {
  sockets.push(ws);
  initMessageHandler(ws);
  initErrorHandler(ws);
  write(ws, queryChainLengthMsg());
};

var initMessageHandler = (ws) => {
  ws.on('message', (data) => {
    var message = JSON.parse(data);
    console.log('Received message' + JSON.stringify(message));
    switch (message.type) {
      case MessageType.QUERY_LATEST:
        write(ws, responseLatestMsg());
        break;
      case MessageType.QUERY_ALL:
        write(ws, responseChainMsg());
        break;
      case MessageType.RESPONSE_BLOCKCHAIN:
        handleBlockchainResponse(message);
        break;
    }
  });
};

var initErrorHandler = (ws) => {
  var closeConnection = (ws) => {
    console.log('connection failed to peer: ' + ws.url);
    sockets.splice(sockets.indexOf(ws), 1);
  };
  ws.on('close', () => closeConnection(ws));
  ws.on('error', () => closeConnection(ws));
};


var generateNextBlock = (blockData) => {
  var previousBlock = getLatestBlock();
  var nextIndex = previousBlock.index + 1;
  var nextTimestamp = new Date().getTime() / 1000;
  var nextHash = calculateHash(nextIndex, previousBlock.hash, nextTimestamp, blockData);
  return new Block(nextIndex, previousBlock.hash, nextTimestamp, blockData, nextHash);
};


var calculateHashForBlock = (block) => {
  return calculateHash(block.index, block.previousHash, block.timestamp, block.data);
};

var calculateHash = (index, previousHash, timestamp, data) => {
  return CryptoJS.SHA256(index + previousHash + timestamp + data).toString();
};

var addBlock = (newBlock) => {
  if (isValidNewBlock(newBlock, getLatestBlock())) {
    blockchain.push(newBlock);
  }
};

var isValidNewBlock = (newBlock, previousBlock) => {
  if (previousBlock.index + 1 !== newBlock.index) {
    console.log('invalid index');
    return false;
  } else if (previousBlock.hash !== newBlock.previousHash) {
    console.log('invalid previoushash');
    return false;
  } else if (calculateHashForBlock(newBlock) !== newBlock.hash) {
    console.log(typeof (newBlock.hash) + ' ' + typeof calculateHashForBlock(newBlock));
    console.log('invalid hash: ' + calculateHashForBlock(newBlock) + ' ' + newBlock.hash);
    return false;
  }
  return true;
};

var connectToPeers = (newPeers) => {
  newPeers.forEach((peer) => {
    var ws = new WebSocket(peer);
    ws.on('open', () => initConnection(ws));
    ws.on('error', () => {
      console.log('connection failed')
    });
  });
};

var handleBlockchainResponse = (message) => {
  var receivedBlocks = JSON.parse(message.data).sort((b1, b2) => (b1.index - b2.index));
  var latestBlockReceived = receivedBlocks[receivedBlocks.length - 1];
  var latestBlockHeld = getLatestBlock();
  if (latestBlockReceived.index > latestBlockHeld.index) {
    console.log('blockchain possibly behind. We got: ' + latestBlockHeld.index + ' Peer got: ' + latestBlockReceived.index);
    if (latestBlockHeld.hash === latestBlockReceived.previousHash) {
      console.log("We can append the received block to our chain");
      blockchain.push(latestBlockReceived);
      broadcast(responseLatestMsg());
    } else if (receivedBlocks.length === 1) {
      console.log("We have to query the chain from our peer");
      broadcast(queryAllMsg());
    } else {
      console.log("Received blockchain is longer than current blockchain");
      replaceChain(receivedBlocks);
    }
  } else {
    console.log('received blockchain is not longer than current blockchain. Do nothing');
  }
};

var replaceChain = (newBlocks) => {
  if (isValidChain(newBlocks) && newBlocks.length > blockchain.length) {
    console.log('Received blockchain is valid. Replacing current blockchain with received blockchain');
    blockchain = newBlocks;
    broadcast(responseLatestMsg());
  } else {
    console.log('Received blockchain invalid');
  }
};

var isValidChain = (blockchainToValidate) => {
  if (JSON.stringify(blockchainToValidate[0]) !== JSON.stringify(getGenesisBlock())) {
    return false;
  }
  var tempBlocks = [blockchainToValidate[0]];
  for (var i = 1; i < blockchainToValidate.length; i++) {
    if (isValidNewBlock(blockchainToValidate[i], tempBlocks[i - 1])) {
      tempBlocks.push(blockchainToValidate[i]);
    } else {
      return false;
    }
  }
  return true;
};

var getLatestBlock = () => blockchain[blockchain.length - 1];
var queryChainLengthMsg = () => ({ 'type': MessageType.QUERY_LATEST });
var queryAllMsg = () => ({ 'type': MessageType.QUERY_ALL });
var responseChainMsg = () => ({
  'type': MessageType.RESPONSE_BLOCKCHAIN, 'data': JSON.stringify(blockchain)
});
var responseLatestMsg = () => ({
  'type': MessageType.RESPONSE_BLOCKCHAIN,
  'data': JSON.stringify([getLatestBlock()])
});

var write = (ws, message) => ws.send(JSON.stringify(message));
var broadcast = (message) => sockets.forEach(socket => write(socket, message));

connectToPeers(initialPeers);
initHttpServer();
initP2PServer();

curl http://localhost:3001/blocks

curl -H "Content-type:application/json" --data '{"data" : "Some data to the first block"}' http://localhost:3001/mineBlock

curl -H "Content-type:application/json" --data '{"peer" : "ws://localhost:6001"}' http://localhost:3001/addPeer

curl http://localhost:3001/peers