Add proxy support to http2 requests in the extension host

[chrmarti]

Previously reverted: #189133

[chrmarti]

Discussion: nodejs/help#4189

[chrmarti]

Previously reverted due to #188676 and https://github.com/github/codespaces/issues/14593.

Status on these:

• @deepak1556 has backported a fix for #188676.
• For https://github.com/github/codespaces/issues/14593 I see grpc-node making connections to ::1 and 127.0.0.1 simultaneously. It seems it then picks the first good one and maybe its detection for a working connection doesn't work with the slightly delayed connect event.

[chrmarti]

Some more findings on the change in grpc behavior:

• Http2Session gets the socket we create that has connecting === true and _handle === undefined.
• It first wraps the socket in a JSStreamSocket because the _handle is undefined: https://github.com/nodejs/node/blob/a94966ffc114e831d4a917a97f9958d3385ab6f7/lib/internal/http2/core.js#L1208
• The wrapper does not have connecting === true and the check of Http2Session whether the socket (now the wrapper) is still connecting does not trigger: https://github.com/nodejs/node/blob/a94966ffc114e831d4a917a97f9958d3385ab6f7/lib/internal/http2/core.js#L1256
• The Http2Session ends up emitting a connect event when the underlying socket is still connecting and that makes grpc pick the ::1 socket because that fires before the 127.0.0.1 socket: https://github.com/grpc/grpc-node/blob/32c816c9d155ee5b9c26adadc9e9b090ee2a4ed2/packages/grpc-js/src/transport.ts#L741
• The ::1 socket then fails with ECONNREFUSED letting the grpc request fail.

The Codespaces extension worked around this by using 127.0.0.1 to connect to instead of localhost which avoids the problem.

When I temporarily set the socket._handle = { isStreamBase: true } to bypass the wrapping in Http2Session and clear it before calling socket.connect(), the session does not emit connect. Though this is probably not a valid fix (only tested in isolation not with the patched module).

[chrmarti]

Opened nodejs/node#49860 for Node.

[kryops]

The system certificate loading V2 also seems to affect the native fetch API.

We conditionally include a polyfill to node-fetch:

import fetch, { Headers, Request, Response } from 'node-fetch';

if (!global.fetch) {
  global.fetch = fetch;
  global.Response = Response;
  global.Headers = Headers;
  global.Request = Request;
}

This stopped working in VS Code 1.82 due to the Node 18 update that made fetch globally available, but apparently without support for system certificates.

When we checked the insiders build, it was working again, but since #194408 it only works with the "Http › Experimental: System Certificates V2" configuration activated.

Does this belong here or should I open a separate issue to track system certificate support for fetch?

[chrmarti]

@kryops This is the right place, thanks.

[kryops]

The system certificate support for fetch seems to have been fixed by #233104 🚀