https://github.com/MetaMask/zero-client
MetaMask ZeroClient and backing iframe service
architecture
here is a comparison of the extension-based and iframe-based architecture
metamask extension:
dapp inpage.js <-> forwarder contentscript.js <-> extension background.jsui popup.js <-> extension background.js
就是当用户通过浏览器通过web3去调用json rpc时，即通过dapp inpage.js，再传给metamask contentscript，再传给metamask background,background将会将要进行的操作传给UI，使其能够在与rpc进行交互之前再一次得到用户的确认，用户确认后就会返回background去与rpc进行交互，然后再将得到的数据通过metamask contentscript-dapp inpage.js传给浏览器
current metamask iframe:
dapp inpage.js <-> iframe background.jsui app.metamask.io <-> iframe background.js
ideal metamask iframe:
dapp inpage.js <-> iframe forwarder <-> sharedworker background.jsui app.metamask.io <-> iframe forwarder <-> sharedworker background.js
ideal unified metamask extension+iframe:
dapp inpage.js <-> iframe forwarder <-> sharedworker background.jsui popup.js <-> iframe forwarder <-> sharedworker background.js
example
npm start
运行：
首先：
userdeMacBook-Pro:zero-client user$ npm install
然后运行npm start:
userdeMacBook-Pro:zero-client user$ npm start> metamask-zeroclient@2.0.0 start /Users/user/zero-client> ./example.sh./example.sh: line 3: beefy: command not found./example.sh: line 4: beefy: command not foundnpm ERR! file shnpm ERR! code ELIFECYCLEnpm ERR! errno ENOENTnpm ERR! syscall spawnnpm ERR! metamask-zeroclient@2.0.0 start: `./example.sh`npm ERR! spawn ENOENTnpm ERR! npm ERR! Failed at the metamask-zeroclient@2.0.0 start script.npm ERR! This is probably not a problem with npm. There is likely additional logging output above.npm ERR! A complete log of this run can be found in:npm ERR! /Users/user/.npm/_logs/2018-11-12T09_26_56_269Z-debug.log
出错，没有安装模块beefy:
userdeMacBook-Pro:zero-client user$ npm install beefy --save
再运行又出错：
userdeMacBook-Pro:zero-client user$ npm start> metamask-zeroclient@2.0.0 start /Users/user/zero-client> ./example.shbeefy (v2.1.8) is listening on http://127.0.0.1:9001beefy (v2.1.8) is listening on http://127.0.0.1:9002200 58ms 261B /200 70ms 1.95KB /bundle.js ➞ /Users/user/zero-client/node_modules/browserify /Users/user/zero-client/.index.js -dError: Cannot find module 'metamask-crx/app/scripts/lib/inpage-provider.js' from '/Users/user/zero-client/lib' at /Users/user/zero-client/node_modules/browser-resolve/node_modules/resolve/lib/async.js:46:17 at process (/Users/user/zero-client/node_modules/browser-resolve/node_modules/resolve/lib/async.js:173:43) at ondir (/Users/user/zero-client/node_modules/browser-resolve/node_modules/resolve/lib/async.js:188:17) at load (/Users/user/zero-client/node_modules/browser-resolve/node_modules/resolve/lib/async.js:69:43) at onex (/Users/user/zero-client/node_modules/browser-resolve/node_modules/resolve/lib/async.js:92:31) at /Users/user/zero-client/node_modules/browser-resolve/node_modules/resolve/lib/async.js:22:47 at FSReqCallback.oncomplete (fs.js:161:21)
发现是在lib/setup-provider.js中调用了metamask-crx模块(metamask chrome extension)，但node_modules中没有
从该网址下载https://github.com/ATNIO/metamask-crx：
const MetamaskInpageProvider = require('metamask-crx/app/scripts/lib/inpage-provider.js') 再运行，还是报错:
Error: Cannot find module 'brfs' from '/Users/user/zero-client/node_modules/metamask-crx' at /Users/user/zero-client/node_modules/resolve/lib/async.js:51:31 at processDirs (/Users/user/zero-client/node_modules/resolve/lib/async.js:185:39) at ondir (/Users/user/zero-client/node_modules/resolve/lib/async.js:200:13) at load (/Users/user/zero-client/node_modules/resolve/lib/async.js:83:43) at onex (/Users/user/zero-client/node_modules/resolve/lib/async.js:108:17) at /Users/user/zero-client/node_modules/resolve/lib/async.js:12:69 at FSReqCallback.oncomplete (fs.js:161:21)
是因为下载下来的metamask-crx模块忘记运行npm install
然后再运行就成功了：
userdeMacBook-Pro:zero-client user$ npm start> metamask-zeroclient@2.0.0 start /Users/user/zero-client> ./example.shbeefy (v2.1.8) is listening on http://127.0.0.1:9001beefy (v2.1.8) is listening on http://127.0.0.1:9002200 50ms 261B /200 63ms 1.95KB /bundle.js ➞ /Users/user/zero-client/node_modules/browserify /Users/user/zero-client/.index.js -d200 2422ms 3.12MB /zero.js ➞ /Users/user/zero-client/node_modules/browserify /Users/user/zero-client/index.js -d200 32ms 427B /404 1ms 12B /background.js200 1497ms 2.33MB /bundle.js ➞ ./node_modules/browserify ./frame.js -d200 25ms 261B /200 116ms 1.95KB /bundle.js ➞ /Users/user/zero-client/node_modules/browserify /Users/user/zero-client/.index.js -d200 1720ms 3.12MB /zero.js ➞ /Users/user/zero-client/node_modules/browserify /Users/user/zero-client/index.js -d200 1ms 189B /favicon.ico (generated)200 13ms 261B /200 12ms 1.95KB /bundle.js ➞ /Users/user/zero-client/node_modules/browserify /Users/user/zero-client/.index.js -d200 1377ms 3.12MB /zero.js ➞ /Users/user/zero-client/node_modules/browserify /Users/user/zero-client/index.js -d200 16ms 427B /
在没有安装metamask插件的浏览器上的结果是：
在安装了metamask插件的浏览器上的结果是：
看到这个运行的结果后，我们可以看看其的代码：
他的代码与之前的mascara的差不多，如果想要看更详细的解释，可看
index.js
const Web3 = require('web3')const setupProvider = require('./lib/setup-provider.js')//// setup web3//var provider = setupProvider()//1 设置providervar web3 = new Web3(provider)web3.currentProvider = providerweb3.setProvider = function(){ console.log('MetaMask - overrode web3.setProvider')}//// export web3//console.log(web3.currentProvider)// console.log(web3.version.network)// console.log(web3.eth.blockNumber)global.web3 = web3
//setup-provider.js
const setupIframe = require('./setup-iframe.js')const MetamaskInpageProvider = require('metamask-crx/app/scripts/lib/inpage-provider.js')module.exports = getProviderfunction getProvider(){//1 if (global.web3) {//2如果有安装插件，那么就使用插件的web3 console.log('MetaMask ZeroClient - using environmental web3 provider') return global.web3.currentProvider } //3如果没有就自己设置 console.log('MetaMask ZeroClient - injecting zero-client iframe!') var iframeStream = setupIframe({ //4设置iframe zeroClientProvider: 'http://localhost:9001', //4服务器端为9001 sandboxAttributes: ['allow-scripts', 'allow-popups', 'allow-same-origin'], }) var inpageProvider = new MetamaskInpageProvider(iframeStream) //6根据iframe流去设置MetamaskInpageProvider return inpageProvider}
//setup-iframe.js
const Iframe = require('iframe')const IframeStream = require('iframe-stream').IframeStreammodule.exports = setupIframefunction setupIframe(opts) {//4 opts = opts || {} var frame = Iframe({ src: opts.zeroClientProvider || 'https://zero.metamask.io/', //5就是如果没有设置服务器，那么就连接zero.metamask.io（docker设置，下面有讲） container: document.head, sandboxAttributes: opts.sandboxAttributes || ['allow-scripts', 'allow-popups'], }) var iframe = frame.iframe var iframeStream = new IframeStream(iframe)//5 然后创建iframe流 return iframeStream}
metamask-crx/app/scripts/lib/inpage-provider.js
const pipe = require('pump')const StreamProvider = require('web3-stream-provider')const LocalStorageStore = require('obs-store')const ObjectMultiplex = require('./obj-multiplex')const createRandomId = require('./random-id')module.exports = MetamaskInpageProviderfunction MetamaskInpageProvider (connectionStream) {//7 const self = this // setup connectionStream multiplexing var multiStream = self.multiStream = ObjectMultiplex()//8生成多路复用流 pipe(//8将多路复用流与iframe流连接 connectionStream, multiStream, connectionStream, (err) => logStreamDisconnectWarning('MetaMask', err) ) // subscribe to metamask public config (one-way) self.publicConfigStore = new LocalStorageStore({ storageKey: 'MetaMask-Config' })//8设置本地存储 pipe(//8在多路复用流中添加publicConfig流用以接收本地存储信息 multiStream.createStream('publicConfig'), self.publicConfigStore, (err) => logStreamDisconnectWarning('MetaMask PublicConfigStore', err) ) // connect to async provider const asyncProvider = self.asyncProvider = new StreamProvider()//8设置rpc provider流 pipe( asyncProvider, multiStream.createStream('provider'), asyncProvider, (err) => logStreamDisconnectWarning('MetaMask RpcProvider', err) ) self.idMap = {} // handle sendAsync requests via asyncProvider self.sendAsync = function (payload, cb) { // rewrite request ids var request = eachJsonMessage(payload, (message) => { //9 10 transformFn即这里的回调参数，payload为message var newId = createRandomId()//11这里是将json rpc中的id随机生成一个更复杂的id值去指明该笔request self.idMap[newId] = message.id //11保留旧的id，因为之后返回时返回的还是旧ID，新id只在过程中使用 message.id = newId return message }) // forward to asyncProvider asyncProvider.sendAsync(request, function (err, res) { if (err) return cb(err) // transform messages to original ids eachJsonMessage(res, (message) => { var oldId = self.idMap[message.id] delete self.idMap[message.id] message.id = oldId return message }) cb(null, res) }) }}MetamaskInpageProvider.prototype.send = function (payload) { const self = this let selectedAddress let result = null switch (payload.method) { case 'eth_accounts': // read from localStorage selectedAddress = self.publicConfigStore.getState().selectedAddress result = selectedAddress ? [selectedAddress] : [] break case 'eth_coinbase': // read from localStorage selectedAddress = self.publicConfigStore.getState().selectedAddress result = selectedAddress break case 'eth_uninstallFilter': self.sendAsync(payload, noop) result = true break case 'net_version': let networkVersion = self.publicConfigStore.getState().networkVersion result = networkVersion break // throw not-supported Error default: var link = 'https://github.com/MetaMask/faq/blob/master/DEVELOPERS.md#dizzy-all-async---think-of-metamask-as-a-light-client' var message = `The MetaMask Web3 object does not support synchronous methods like ${payload.method} without a callback parameter. See ${link} for details.` throw new Error(message) } // return the result return { id: payload.id, jsonrpc: payload.jsonrpc, result: result, }}MetamaskInpageProvider.prototype.sendAsync = function () { throw new Error('MetamaskInpageProvider - sendAsync not overwritten')}MetamaskInpageProvider.prototype.isConnected = function () { return true}MetamaskInpageProvider.prototype.isMetaMask = true// utilfunction eachJsonMessage (payload, transformFn) {//9 if (Array.isArray(payload)) {//9如果是数组，说明一次要执行多个request return payload.map(transformFn)//9所以将数组中的request一个个传入transformFn，最后传出结果的数组 } else { return transformFn(payload)//9如果不是，则说明是一个request，直接做transformFn的参数即可 }}function logStreamDisconnectWarning(remoteLabel, err){ let warningMsg = `MetamaskInpageProvider - lost connection to ${remoteLabel}` if (err) warningMsg += '\n' + err.stack console.warn(warningMsg)}function noop () {}
从上面的代码中我们可以看见，如果没有设置provider的话（zeroClientProvider: 'http://localhost:9001'），那么就会默认为https://zero.metamask.io/
这是通过docker进行设置的，如下：
Dockerfile
FROM node:0.12MAINTAINER kumavis# setup app dirRUN mkdir -p /www/WORKDIR /www/# install dependenciesCOPY ./package.json /www/package.jsonRUN npm install# copy over app dirCOPY ./ /www/# run testsRUN npm test# start serverCMD npm start# expose serverEXPOSE 9000
从这里我们可以看出基本上就是本文档的复制粘贴，部署了一个服务器，并提供了9000作为端口
docker-compose.yml
zeroClient: image: kumavis/zeroclient restart: always environment: VIRTUAL_HOST: "zero.metamask.io" VIRTUAL_PORT: "9000" PORT: "9000" ports: - "9000"
因为该项目的作者已经将该镜像上传，所以我们可以根据 docker-compose.yml的设置直接拉取镜像进行使用：
userdeMBP:zero-client user$ docker-compose upPulling zeroClient (kumavis/zeroclient:)...latest: Pulling from kumavis/zeroclientd4bce7fd68df: Pull completea3ed95caeb02: Pull complete816152842605: Pull complete5dcab2c7e430: Pull completedc54ada22a60: Pull completef4dbf915606d: Pull complete2e6a016344c7: Pull complete310ce789aae0: Pull completed9f04797303f: Pull completee69d1d8ba6cd: Pull complete508a0e5f7217: Pull completeDigest: sha256:6a7936b08541ced92fc35f63033046942df09e6a48a56f199de315eac002be51Status: Downloaded newer image for kumavis/zeroclient:latestCreating zero-client_zeroClient_1 ... doneAttaching to zero-client_zeroClient_1zeroClient_1 | zeroClient_1 | > metamask-zeroclient@1.0.0 start /wwwzeroClient_1 | > node server.jszeroClient_1 | zeroClient_1 | MetaMask ZeroClient iframe server listening on 9000
然后这时候将//setup-provider.js中的http://localhost:9001去掉，让其连接https://zero.metamask.io/：
得到结果：
然后在shared-worker文件夹中我们能够看到有：
//client.js
var worker = new SharedWorker("worker.js");var id = Number.MAX_SAFE_INTEGER*Math.random()//3 随机生成id值worker.port.addEventListener("message", function(e) { console.log(e) console.log(id) console.log("message") console.log(e.data);}, false);worker.port.start();//1 激活端口// post a message to the shared web workerworker.port.postMessage(id)//3 发送id,触发server.js的"message"事件 扩展，参考https://www.jb51.net/html5/551063.html：
SharedWorker类（html5）
SharedWorker的实质在于share，不同的线程可以共享一个线程，他们的数据也是共享的。
本例子是通过addEventListener()方法监听message事件，需要worker.port.start()方法激活端口。
也有下面这样的写法：
worker.port.onmessage = function(e) { console.log(e) console.log(id) console.log("message") console.log(e.data);} 使用事件句柄的方式将听message事件，不需要调用worker.port.start()
不同于worker，当有人和他通信时触发connect事件（如下），然后他的message事件是绑定在messagePort对象上的
//server.js
var connections = 0 // count active connectionsself.addEventListener("connect", function (e) {//2 进行连接var port = e.ports[0] connections++ port.addEventListener("message", function (e) {//4 收到消息id = e.data port.postMessage("Hello " + e.data + " (port #" + connections + ")")//5 post回消息，然后触发client.js的"message"事件 }, false) port.start()//2 打开端口}, false) run example
beefy client.js:index.js server.js:worker.js --live --open
然后我们为了将这个例子运行起来，需要对package.json进行更改，添加"example"：
"scripts": { "test": "echo \"Error: no tests yet\" && exit 0", "start": "./example.sh", "example": "beefy shared-worker/client.js:index.js shared-worker/server.js:worker.js 9003 --live --open " }, 这里没有设置端口，会随机使用一个端口，但是你也可以自己设置，这里我们设置为9003，然后运行：
userdeMacBook-Pro:zero-client user$ npm run example> metamask-zeroclient@2.0.0 example /Users/user/zero-client> beefy shared-worker/client.js:index.js shared-worker/server.js:worker.js 9003 --live --open beefy (v2.1.8) is listening on http://127.0.0.1:9003200 70ms 552B /200 793ms 2.36KB /index.js ➞ ./node_modules/browserify ./shared-worker/client.js -d200 30ms 552B /200 17ms 2.36KB /index.js ➞ ./node_modules/browserify ./shared-worker/client.js -d200 36ms 552B /200 10ms 2.36KB /index.js ➞ ./node_modules/browserify ./shared-worker/client.js -d200 19ms 552B /200 8ms 2.36KB /index.js ➞ ./node_modules/browserify ./shared-worker/client.js -d
并且将index.html上的bundle.js改为index.js:
MetaMask ZeroClient Iframe Hello! I am the MetaMask iframe.
返回：
刷新一次可以看见port 4变成了port 5，是第五次访问
