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const pump = require('pump')
const RpcEngine = require('json-rpc-engine')
const createErrorMiddleware = require('./createErrorMiddleware')
const createIdRemapMiddleware = require('json-rpc-engine/src/idRemapMiddleware')
const createStreamMiddleware = require('json-rpc-middleware-stream')
const LocalStorageStore = require('obs-store')
const asStream = require('obs-store/lib/asStream')
const ObjectMultiplex = require('obj-multiplex')
module.exports = MetamaskInpageProvider
function MetamaskInpageProvider (connectionStream) {
const self = this
// setup connectionStream multiplexing
const mux = self.mux = new ObjectMultiplex()
pump(
connectionStream,
mux,
connectionStream,
(err) => logStreamDisconnectWarning('MetaMask', err)
)
// subscribe to metamask public config (one-way)
self.publicConfigStore = new LocalStorageStore({ storageKey: 'MetaMask-Config' })
pump(
mux.createStream('publicConfig'),
asStream(self.publicConfigStore),
(err) => logStreamDisconnectWarning('MetaMask PublicConfigStore', err)
)
// ignore phishing warning message (handled elsewhere)
mux.ignoreStream('phishing')
// connect to async provider
const streamMiddleware = createStreamMiddleware()
pump(
streamMiddleware.stream,
mux.createStream('provider'),
streamMiddleware.stream,
(err) => logStreamDisconnectWarning('MetaMask RpcProvider', err)
)
// handle sendAsync requests via dapp-side rpc engine
const rpcEngine = new RpcEngine()
rpcEngine.push(createIdRemapMiddleware())
rpcEngine.push(createErrorMiddleware())
rpcEngine.push(streamMiddleware)
self.rpcEngine = rpcEngine
}
// handle sendAsync requests via asyncProvider
// also remap ids inbound and outbound
MetamaskInpageProvider.prototype.sendAsync = function (payload, cb) {
const self = this
self.rpcEngine.handle(payload, cb)
}
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 || null
break
case 'eth_uninstallFilter':
self.sendAsync(payload, noop)
result = true
break
case 'net_version':
const networkVersion = self.publicConfigStore.getState().networkVersion
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)
}
function noop () {}
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