fix: Only emit correctly-formed JSONRPC message

packages/fether-electron/src/main/app/ipcChannel/index.js

@@ -31,10 +31,25 @@ class IpcChannel extends EventEmitter {
         this._sendQueued();
         resolve(true);
       });
+
+      // We get data from the socket by chunks, and 1 chunk !== 1 Rpc message
+      // Sometimes 1 chunk is multiple messages, sometimes we get partial
+      // messages.
+      // https://github.com/paritytech/fether/issues/562
+
+      // The last element in a '\n'-separate chunk. Will be `""` if the
+      // last element was a correctly-formed message, or will hold the
+      // ill-formed message otherwise.
+      let lastData = '';
       socket.on('data', data_ => {
-        const data = data_.toString();
-        // Sometimes we receive multiple messages at once
-        const messages = data.split(/\r?\n/).filter(Boolean);
+        // If the last data was truncated, then we concatenate to the new data
+        // we just received
+        const data = `${lastData}${data_.toString()}`;
+
+        // All messages are separated by a '\n'
+        const messages = data.split(/\n/);
+        lastData = messages.pop(); // Will hold "" or an ill-formed JSONRPC message
+
         messages.forEach(data => {
           this.emit('message', data);
         });

packages/fether-react/src/utils/PostMessageProvider.js

@@ -14,11 +14,15 @@
 // You should have received a copy of the GNU General Public License
 // along with Parity.  If not, see <http://www.gnu.org/licenses/>.
 
-import * as postMessage from './postMessage';
 import EventEmitter from 'eventemitter3';
 
+import Debug from './debug';
+import * as postMessage from './postMessage';
+
+const debug = Debug('PostMessageProvider');
+
 export default class PostMessageProvider extends EventEmitter {
-  constructor (destination, source) {
+  constructor (destination) {
     super();
 
     this._destination = destination || window.parent;
@@ -136,20 +140,50 @@ export default class PostMessageProvider extends EventEmitter {
   }
 
   _receiveMessage (raw) {
-    const parsed = JSON.parse(raw);
+    let parsed;
+    try {
+      parsed = JSON.parse(raw);
+    } catch (err) {
+      // Should not happen anymore, since the following issue is fixed
+      // https://github.com/paritytech/fether/issues/562
+      debug(`Cannot parse ${raw}. Ignoring message.`);
+
+      return;
+    }
+
     const { id, error } = parsed;
     const subscription = parsed.params && parsed.params.subscription;
 
     if (subscription) {
       // subscription notification
       const result = parsed.params.result;
       let messageId = this._subscriptionsToId[subscription];
-      this._messages[messageId].callback(error && new Error(error), result);
+
+      // Sometimes we receive results for a subscription that we have never
+      // seen before. Should not happen.
+      if (!this._messages[messageId]) {
+        debug(`Got result for unknown subscription ${subscription}`);
+
+        return;
+      }
+
+      this._messages[messageId].callback(
+        error && new Error(error.message),
+        result
+      );
     } else {
+      // Sometimes we receive results for an id that we have never seen before.
+      // Should not happen.
+      if (!this._messages[id]) {
+        debug(`Got result for unknown id ${id}`);
+
+        return;
+      }
+
       // request response
       const result = parsed.result;
       if (error) {
-        this._messages[id].reject(new Error(error));
+        this._messages[id].reject(new Error(error.message));
       } else {
         this._messages[id].resolve(result);