Tunnel to WSL2 refuses connection

[xisui-MSFT]

Does this issue occur when all extensions are disabled?: Yes/No

• VS Code Version: 1.79.2
• OS Version: Windows 11 (22621.1926) + WSL2 (Ubuntu 22.04)

Steps to Reproduce:

1. Create a workspace extension, in which create a server listening to a port (workspacePort)
2. Create a UI extension, in which create a tunnel, like this (proposed API tunnels is required):

   tunnel = await vscode.workspace.openTunnel({ remoteAddress: { port: workspacePort, host: 'localhost' } });

3. In the UI extension, connect to the tunnel:

   const tunnelConnection = new Promise<void>((resolve, reject) => {
   
       const doConnect = () => tunnelSocket.connect(tunnelPort, 'localhost', () => resolve());
   
       tunnelSocket.on('data', data => {
           ... // Do something
       });
   
       tunnelSocket.on('end', () => {
           ... // Do something
           resolve();
       });
   
       tunnelSocket.on('error', err => {
           if (err) {
               console.log(`Error: ${err.message}`);
           }
   
           ... // Do something
           reject();
       });
   
       doConnect();
   });

4. Run the extensions, so that the UI extension runs locally, and the workspace extension runs in WSL. Notice that error messages like Error: connect ECONNREFUSED 127.0.0.1:46871 are shown in the console.

A side question: This does NOT repro for docker containers or codespaces. But I wonder if there's a better way to do raw TCP communication between host and WSL?

[xisui-MSFT]

@alexr00 Could you please take a look?

[alexr00]

This is by design. We do not support port forwarding with a WSL connection. Someone else just made a feature request to support port forwarding with WSL: microsoft/vscode-remote-release#8621

[sandros94]

@xisui-MSFT, if you are interested, be sure to go about and upvote that feature request.