2019独角兽企业重金招聘Python工程师标准>>> 
本系统采用express框架
项目初始化
npm init安装相关库
npm install body-parser --save
npm install crypto-js --save
npm install express --save
npm install ws --save
package.json内容如下
{
"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"
}
}创建main.js 代码如下
'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();
执行命令 npm run start
打开另一个窗口 分别执行以下命令 ，观察第一个窗口的输出
获取一个 blockchain
curl http://localhost:3001/blocks
创建 block
curl -H "Content-type:application/json" --data '{"data" : "Some data to the first block"}' http://localhost:3001/mineBlock
添加 peer
curl -H "Content-type:application/json" --data '{"peer" : "ws://localhost:6001"}' http://localhost:3001/addPeer
连接peers
curl http://localhost:3001/peersgithub地址 https://github.com/lilugirl/corechain