Use proper path for websocket

lib/internal/inspect-protocol.js

@@ -23,6 +23,7 @@
 const crypto = require('crypto');
 const { EventEmitter } = require('events');
 const http = require('http');
+const URL = require('url');
 const util = require('util');
 
 const debuglog = util.debuglog('inspect');
@@ -228,7 +229,53 @@ class Client extends EventEmitter {
     });
   }
 
+  _fetchJSON(urlPath) {
+    return new Promise((resolve, reject) => {
+      const httpReq = http.get({
+        host: this._host,
+        port: this._port,
+        path: urlPath,
+      });
+
+      const chunks = [];
+
+      function onResponse(httpRes) {
+        function parseChunks() {
+          const resBody = Buffer.concat(chunks).toString();
+          if (httpRes.statusCode !== 200) {
+            reject(new Error(`Unexpected ${httpRes.statusCode}: ${resBody}`));
+            return;
+          }
+          try {
+            resolve(JSON.parse(resBody));
+          } catch (parseError) {
+            reject(new Error(`Response did not contain valid JSON: ${resBody}`));
+            return;
+          }
+        }
+
+        httpRes.on('error', reject);
+        httpRes.on('data', chunk => chunks.push(chunk));
+        httpRes.on('end', parseChunks);
+      }
+
+      httpReq.on('error', reject);
+      httpReq.on('response', onResponse);
+    });
+  }
+
   connect() {
+    return this._discoverWebsocketPath()
+      .then(urlPath => this._connectWebsocket(urlPath));
+  }
+
+  _discoverWebsocketPath() {
+    return this._fetchJSON('/json')
+      .then(([{ webSocketDebuggerUrl }]) =>
+        URL.parse(webSocketDebuggerUrl).path);
+  }
+
+  _connectWebsocket(urlPath) {
     this.reset();
 
     const key1 = crypto.randomBytes(16).toString('base64');
@@ -237,18 +284,20 @@ class Client extends EventEmitter {
     const httpReq = this._http = http.request({
       host: this._host,
       port: this._port,
-      path: '/node',
+      path: urlPath,
       headers: {
         Connection: 'Upgrade',
         Upgrade: 'websocket',
         'Sec-WebSocket-Key': key1,
+        'Sec-WebSocket-Version': '13',
       },
     });
     httpReq.on('error', e => {
       this.emit('error', e);
     });
     httpReq.on('response', httpRes => {
       if (httpRes.statusCode >= 400) {
+        process.stderr.write(`Unexpected HTTP response: ${httpRes.statusCode}\n`);
         httpRes.pipe(process.stderr);
       } else {
         httpRes.pipe(process.stderr);