MetaMask/metamask-inpage-provider

npm install metamask-inpage-provider -S

const log = require(‘loglevel‘)/** * JSON-RPC error object * * @typedef {Object} RpcError * @property {number} code - Indicates the error type that occurred * @property {Object} [data] - Contains additional information about the error * @property {string} [message] - Short description of the error *//** * Middleware configuration object * * @typedef {Object} MiddlewareConfig * @property {boolean} [override] - Use RPC_ERRORS message in place of provider message *//** * Map of standard and non-standard RPC error codes to messages */const RPC_ERRORS = { ?1: ‘An unauthorized action was attempted.‘, ?2: ‘A disallowed action was attempted.‘, ?3: ‘An execution error occurred.‘, ?[-32600]: ‘The JSON sent is not a valid Request object.‘, ?[-32601]: ‘The method does not exist / is not available.‘, ?[-32602]: ‘Invalid method parameter(s).‘, ?[-32603]: ‘Internal JSON-RPC error.‘, ?[-32700]: ‘Invalid JSON was received by the server. An error occurred on the server while parsing the JSON text.‘, ?internal: ‘Internal server error.‘, ?unknown: ‘Unknown JSON-RPC error.‘,}/** * Modifies a JSON-RPC error object in-place to add a human-readable message, * optionally overriding any provider-supplied message * * @param {RpcError} error - JSON-RPC error object * @param {boolean} override - Use RPC_ERRORS message in place of provider message */function sanitizeRPCError (error, override) { ?if (error.message && !override) { return error } ?const message = error.code > -31099 && error.code < -32100 ? RPC_ERRORS.internal : RPC_ERRORS[error.code]//判断错误类型并获得错误message ?error.message = message || RPC_ERRORS.unknown}/** * json-rpc-engine middleware that both logs standard and non-standard error * messages and ends middleware stack traversal if an error is encountered * * @param {MiddlewareConfig} [config={override:true}] - Middleware configuration * @returns {Function} json-rpc-engine middleware function */function createErrorMiddleware ({ override = true } = {}) { ?return (req, res, next) => { ???next(done => { ?????const { error } = res ?????if (!error) { return done() } ?????sanitizeRPCError(error) ?????log.error(`MetaMask - RPC Error: ${error.message}`, error) ?????done() ???}) ?}}module.exports = createErrorMiddleware

const pump = require(‘pump‘)//看本博客pump模块的学习-metamaskconst RpcEngine = require(‘json-rpc-engine‘)//看本博客MetaMask/json-rpc-engineconst createErrorMiddleware = require(‘./createErrorMiddleware‘)//检查json rpc产生的错误const createIdRemapMiddleware = require(‘json-rpc-engine/src/idRemapMiddleware‘)创建一个独特的id来标识json rpc，不然它的id很多都是相同的1，2等，看本博客MetaMask/json-rpc-engineconst createJsonRpcStream = require(‘json-rpc-middleware-stream‘)//看本博客的MetaMask/json-rpc-middleware-streamconst LocalStorageStore = require(‘obs-store‘)//看本博客MetaMask/obs-storeconst asStream = require(‘obs-store/lib/asStream‘)//看本博客MetaMask/obs-storeconst ObjectMultiplex = require(‘obj-multiplex‘)//看博客kumavis/obj-multiplexconst util = require(‘util‘)const SafeEventEmitter = require(‘safe-event-emitter‘)//看博客MetaMask/safe-event-emittermodule.exports = MetamaskInpageProviderutil.inherits(MetamaskInpageProvider, SafeEventEmitter)function MetamaskInpageProvider (connectionStream) { ?const self = this ?// super constructor ?SafeEventEmitter.call(self) ?// setup connectionStream multiplexing ?const mux = self.mux = new ObjectMultiplex() ?pump( ???connectionStream, ???mux, ???connectionStream, ???logStreamDisconnectWarning.bind(this, ‘MetaMask‘) ?) ?// subscribe to metamask public config (one-way) ?self.publicConfigStore = new LocalStorageStore({ storageKey: ‘MetaMask-Config‘ })//定义了一个在浏览器中storageKey为‘MetaMask-Config‘的本地存储，用于存储一些区块链的账户信息，网络信息 ?pump(//进行浏览器本地信息存储 ???mux.createStream(‘publicConfig‘),//创建name为publicConfig的子流 ???asStream(self.publicConfigStore), ???logStreamDisconnectWarning.bind(this, ‘MetaMask PublicConfigStore‘)//logStreamDisconnectWarning函数下面有定义，‘MetaMask PublicConfigStore‘为error说明， ?) ?// ignore phishing warning message (handled elsewhere) ?mux.ignoreStream(‘phishing‘)//这里不对name为phishing的流进行处理 ?// connect to async provider ?const jsonRpcConnection = createJsonRpcStream()// ?pump(//构建provider，接受浏览器传来的json rpc，并响应 ???jsonRpcConnection.stream, ???mux.createStream(‘provider‘), ???jsonRpcConnection.stream, ???logStreamDisconnectWarning.bind(this, ‘MetaMask RpcProvider‘) ?) ?// handle sendAsync requests via dapp-side rpc engine ?const rpcEngine = new RpcEngine() 看了本博客MetaMask/json-rpc-engine后，可以知道这是push进将要对接受到的json rpc调用的处理 ?rpcEngine.push(createIdRemapMiddleware())//获得个unique id拿来使用 ?rpcEngine.push(createErrorMiddleware()) //进行错误的处理 ?rpcEngine.push(jsonRpcConnection.middleware) //将json rpc 请求写入createJsonRpcStream双工流中 ?self.rpcEngine = rpcEngine ?// forward json rpc notifications ?jsonRpcConnection.events.on(‘notification‘, function(payload) {//设置json-rpc-middleware-stream流相应的‘notification‘事件 ???self.emit(‘data‘, null, payload) //触发data事件 ?}) ?// Work around for https://github.com/metamask/metamask-extension/issues/5459 ?// drizzle accidently breaking the `this` reference ?self.send = self.send.bind(self) ?self.sendAsync = self.sendAsync.bind(self)}// Web3 1.0 provider uses `send` with a callback for async queriesMetamaskInpageProvider.prototype.send = function (payload, callback) {//web3调用send() ?const self = this ?if (callback) {//如果是异步带回调的，就调用sendAsync ???self.sendAsync(payload, callback) ?} else {//否则就调用_sendSync ???return self._sendSync(payload) ?}}// handle sendAsync requests via asyncProvider// also remap ids inbound and outboundMetamaskInpageProvider.prototype.sendAsync = function (payload, cb) { ?const self = this ?if (payload.method === ‘eth_signTypedData‘) { ???console.warn(‘MetaMask: This experimental version of eth_signTypedData will be deprecated in the next release in favor of the standard as defined in EIP-712. See https://git.io/fNzPl for more information on the new standard.‘) ?} ?self.rpcEngine.handle(payload, cb)//该json rpc就会被处理}MetamaskInpageProvider.prototype._sendSync = function (payload) { ?const self = this ?let selectedAddress ?let result = null ?switch (payload.method) { ???case ‘eth_accounts‘: ?????// read from localStorage ?????selectedAddress = self.publicConfigStore.getState().selectedAddress //从本地存储中获得账户信息 ?????result = selectedAddress ? [selectedAddress] : [] ?????break ???case ‘eth_coinbase‘: ?????// read from localStorage ?????selectedAddress = self.publicConfigStore.getState().selectedAddress//从本地存储中获得账户信息 ?????result = selectedAddress || null ?????break ???case ‘eth_uninstallFilter‘: ?????self.sendAsync(payload, noop) //设置回调为{}再调用sendAsync ?????result = true ?????break ???case ‘net_version‘: ?????const networkVersion = self.publicConfigStore.getState().networkVersion//从本地存储中获得网络信息 ?????result = networkVersion || null ?????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.isConnected = function () { ?return true}MetamaskInpageProvider.prototype.isMetaMask = true// utilfunction logStreamDisconnectWarning (remoteLabel, err) { ?let warningMsg = `MetamaskInpageProvider - lost connection to ${remoteLabel}` ?if (err) warningMsg += ‘\n‘ + err.stack ?console.warn(warningMsg) ?const listeners = this.listenerCount(‘error‘) ?if (listeners > 0) { ???this.emit(‘error‘, warningMsg) ?}}function noop () {}