MetaMask/metamask-inpage-provider
https://github.com/MetaMask/metamask-inpage-provider
Used to initialize the inpage ethereum provider injected by MetaMask.
Installation
npm install metamask-inpage-provider -S
metamask-inpage-provider/createErrorMiddleware.js
处理JSON-RPC调用是出现的错误，并将错误记录到日志中
loglevel是JavaScript的最小轻量级日志记录，它没有控制台的缺点，替代了console.log()并且对于基于级别的日志和过滤是十分友好的，本博客loglevel-metamask
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
metamask-inpage-provider/index.js
这个库的作用有设置浏览器本地信息存储publicConfig流、构建RpcProvider双向传送json rpc及其结果流，以及对从浏览器中得到的json rpc进行处理，send/sendsync的处理是不同的，然后将他们根据得到的特殊id存储到数组中，等待传送到区块链进行处理
const pump = require('pump')//看本博客pump模块的学习-metamask const RpcEngine = require('json-rpc-engine')//看本博客MetaMask/json-rpc-engine const 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-engine const createJsonRpcStream = require('json-rpc-middleware-stream')//看本博客的MetaMask/json-rpc-middleware-stream const LocalStorageStore = require('obs-store')//看本博客MetaMask/obs-store const asStream = require('obs-store/lib/asStream')//看本博客MetaMask/obs-store const ObjectMultiplex = require('obj-multiplex')//看博客kumavis/obj-multiplex const util = require('util') const SafeEventEmitter = require('safe-event-emitter')//看博客MetaMask/safe-event-emitter module.exports = MetamaskInpageProvider util.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 queries MetamaskInpageProvider.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 outbound MetamaskInpageProvider.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 // util function 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 () {}
Usage
MetamaskInpageProvider的使用：
// Create a stream to a remote provider: var metamaskStream = new LocalMessageDuplexStream({ name: 'inpage', target: 'contentscript', }) // compose the inpage provider var inpageProvider = new MetamaskInpageProvider(metamaskStream)
