Disable the webext if the bridge is unreachable

proxy/init-webext.js

@@ -31,6 +31,20 @@ class WebExtUI extends UI {
       this.setEnabled(false);
       return;
     }
+    (new Promise((resolve, reject) => {
+      const ws = WS.makeWebsocket(config.relayAddr);
+      ws.onopen = () => {
+        resolve();
+        ws.close();
+      };
+      ws.onerror = () => {
+        this.missingFeature = 'popupBridgeUnreachable';
+        this.setEnabled(false);
+        reject('Could not connect to bridge.');
+        ws.close();
+      };
+    }))
+    .then(() => {
       chrome.storage.local.get("snowflake-enabled", (result) => {
         let enabled = this.enabled;
         if (result['snowflake-enabled'] !== void 0) {
@@ -40,6 +54,10 @@ class WebExtUI extends UI {
         }
         this.setEnabled(enabled);
       });
+    })
+    .catch((e) => {
+      log(e);
+    });
   }
 
   postActive() {

proxy/static/_locales/en_US/messages.json

@@ -23,6 +23,9 @@
   "popupWebRTCOff": {
     "message": "WebRTC feature is not detected."
   },
+  "popupBridgeUnreachable": {
+    "message": "Could not connect to the bridge."
+  },
   "popupDescOn": {
     "message": "Number of users your Snowflake has helped circumvent censorship in the last 24 hours: $1"
   },