1 files changed, 30 insertions, 15 deletions
diff --git a/app/scripts/metamask-controller.js b/app/scripts/metamask-controller.js
index 393154c60..17d38d43c 100644
--- a/app/scripts/metamask-controller.js
+++ b/app/scripts/metamask-controller.js
@@ -1391,6 +1391,32 @@ module.exports = class MetamaskController extends EventEmitter {
    * @param {string} origin - The URI of the requesting resource.
    */
   setupProviderConnection (outStream, origin, publicApi) {
+    const getSiteMetadata = publicApi && publicApi.getSiteMetadata
+    const engine = this.setupProviderEngine(origin, getSiteMetadata)
+
+    // setup connection
+    const providerStream = createEngineStream({ engine })
+
+    pump(
+      outStream,
+      providerStream,
+      outStream,
+      (err) => {
+        // cleanup filter polyfill middleware
+        engine._middleware.forEach((mid) => {
+          if (mid.destroy && typeof mid.destroy === 'function') {
+            mid.destroy()
+          }
+        })
+        if (err) log.error(err)
+      }
+    )
+  }
+
+  /**
+   * A method for creating a provider that is safely restricted for the requesting domain.
+   **/
+  setupProviderEngine (origin, getSiteMetadata) {
     // setup json rpc engine stack
     const engine = new RpcEngine()
     const provider = this.provider
@@ -1398,6 +1424,7 @@ module.exports = class MetamaskController extends EventEmitter {
 
     // create filter polyfill middleware
     const filterMiddleware = createFilterMiddleware({ provider, blockTracker })
+
     // create subscription polyfill middleware
     const subscriptionManager = createSubscriptionManager({ provider, blockTracker })
     subscriptionManager.events.on('notification', (message) => engine.emit('notification', message))
@@ -1413,24 +1440,11 @@ module.exports = class MetamaskController extends EventEmitter {
     // requestAccounts
     engine.push(this.providerApprovalController.createMiddleware({
       origin,
-      getSiteMetadata: publicApi && publicApi.getSiteMetadata,
+      getSiteMetadata,
     }))
     // forward to metamask primary provider
     engine.push(providerAsMiddleware(provider))
-
-    // setup connection
-    const providerStream = createEngineStream({ engine })
-
-    pump(
-      outStream,
-      providerStream,
-      outStream,
-      (err) => {
-        // cleanup filter polyfill middleware
-        filterMiddleware.destroy()
-        if (err) log.error(err)
-      }
-    )
+    return engine
   }
 
   /**
@@ -1797,3 +1811,4 @@ module.exports = class MetamaskController extends EventEmitter {
     return this.keyringController.setLocked()
   }
 }
+