3 files changed, 73 insertions, 0 deletions

diff --git a/app/scripts/background.js b/app/scripts/background.js
index 7eb7b1255..c0b00730d 100644
--- a/app/scripts/background.js
+++ b/app/scripts/background.js
@@ -253,6 +253,7 @@ function setupController (initState, initLangCode) {
     showUnconfirmedMessage: triggerUi,
     unlockAccountMessage: triggerUi,
     showUnapprovedTx: triggerUi,
+    showAddTokenUi: triggerUi,
     // initial state
     initState,
     // initial locale code
@@ -446,3 +447,4 @@ extension.runtime.onInstalled.addListener(function (details) {
     extension.tabs.create({url: 'https://metamask.io/#how-it-works'})
   }
 })
+
diff --git a/app/scripts/controllers/preferences.js b/app/scripts/controllers/preferences.js
index 707fd7de9..a42bb77b3 100644
--- a/app/scripts/controllers/preferences.js
+++ b/app/scripts/controllers/preferences.js
@@ -1,5 +1,6 @@
 const ObservableStore = require('obs-store')
 const normalizeAddress = require('eth-sig-util').normalize
+const isValidAddress = require('ethereumjs-util').isValidAddress
 const extend = require('xtend')
 
 
@@ -27,6 +28,7 @@ class PreferencesController {
       currentAccountTab: 'history',
       accountTokens: {},
       tokens: [],
+      suggestedTokens: {},
       useBlockie: false,
       featureFlags: {},
       currentLocale: opts.initLangCode,
@@ -37,6 +39,7 @@ class PreferencesController {
     this.diagnostics = opts.diagnostics
     this.network = opts.network
     this.store = new ObservableStore(initState)
+    this.showAddTokenUi = opts.showAddTokenUi
     this._subscribeProviderType()
   }
 // PUBLIC METHODS
@@ -51,6 +54,47 @@ class PreferencesController {
     this.store.updateState({ useBlockie: val })
   }
 
+  getSuggestedTokens () {
+    return this.store.getState().suggestedTokens
+  }
+
+  addSuggestedToken (tokenOpts) {
+    this._validateSuggestedTokenParams(tokenOpts)
+    const suggested = this.getSuggestedTokens()
+    const { rawAddress, symbol, decimals } = tokenOpts
+    const address = normalizeAddress(rawAddress)
+    const newEntry = { address, symbol, decimals }
+    suggested[address] = newEntry
+    this.store.updateState({ suggestedTokens: suggested })
+  }
+
+  /**
+   * RPC engine middleware for requesting new token added
+   *
+   * @param req
+   * @param res
+   * @param {Function} - next
+   * @param {Function} - end
+   */
+  requestAddToken (req, res, next, end) {
+    if (req.method === 'eth_watchToken') {
+      const [ rawAddress, symbol, decimals ] = req.params
+      this._validateSuggestedTokenParams({ rawAddress, symbol, decimals })
+      const tokenOpts = {
+        rawAddress,
+        decimals,
+        symbol,
+      }
+
+      this.addSuggestedToken(tokenOpts)
+      this.showAddTokenUi()
+      res.result = rawAddress
+      return end()
+    } else {
+      return next()
+    }
+  }
+
   /**
    * Getter for the `useBlockie` property
    *
@@ -186,6 +230,13 @@ class PreferencesController {
     return selected
   }
 
+  removeSuggestedTokens () {
+    return new Promise((resolve, reject) => {
+      this.store.updateState({ suggestedTokens: {} })
+      resolve()
+    })
+  }
+
   /**
    * Setter for the `selectedAddress` property
    *
@@ -387,6 +438,23 @@ class PreferencesController {
   //
   // PRIVATE METHODS
   //
+
+  /**
+   * Validates that the passed options for suggested token have all required properties.
+   *
+   * @param {Object} opts The options object to validate
+   * @throws {string} Throw a custom error indicating that address, symbol and/or decimals
+   * doesn't fulfill requirements
+   *
+   */
+  _validateSuggestedTokenParams (opts) {
+    const { rawAddress, symbol, decimals } = opts
+    if (!rawAddress || !symbol || !decimals) throw new Error(`Cannot suggest token without address, symbol, and decimals`)
+    if (!(symbol.length < 5)) throw new Error(`Invalid symbol ${symbol} more than four characters`)
+    const numDecimals = parseInt(decimals, 10)
+    if (isNaN(numDecimals) || numDecimals > 18 || numDecimals < 0) throw new Error(`Invalid decimals ${decimals}`)
+    if (!isValidAddress(rawAddress)) throw new Error(`Invalid address ${rawAddress}`)
+    
   /**
    * Subscription to network provider type.
    *
diff --git a/app/scripts/metamask-controller.js b/app/scripts/metamask-controller.js
index db323e3fe..1464b16a6 100644
--- a/app/scripts/metamask-controller.js
+++ b/app/scripts/metamask-controller.js
@@ -87,6 +87,7 @@ module.exports = class MetamaskController extends EventEmitter {
     this.preferencesController = new PreferencesController({
       initState: initState.PreferencesController,
       initLangCode: opts.initLangCode,
+      showAddTokenUi: opts.showAddTokenUi,
       network: this.networkController,
     })
 
@@ -392,6 +393,7 @@ module.exports = class MetamaskController extends EventEmitter {
       setSelectedAddress: nodeify(preferencesController.setSelectedAddress, preferencesController),
       addToken: nodeify(preferencesController.addToken, preferencesController),
       removeToken: nodeify(preferencesController.removeToken, preferencesController),
+      removeSuggestedTokens: nodeify(preferencesController.removeSuggestedTokens, preferencesController),
       setCurrentAccountTab: nodeify(preferencesController.setCurrentAccountTab, preferencesController),
       setAccountLabel: nodeify(preferencesController.setAccountLabel, preferencesController),
       setFeatureFlag: nodeify(preferencesController.setFeatureFlag, preferencesController),
@@ -1243,6 +1245,7 @@ module.exports = class MetamaskController extends EventEmitter {
     engine.push(createOriginMiddleware({ origin }))
     engine.push(createLoggerMiddleware({ origin }))
     engine.push(filterMiddleware)
+    engine.push(this.preferencesController.requestAddToken.bind(this.preferencesController))
     engine.push(createProviderMiddleware({ provider: this.provider }))
 
     // setup connection