fix(NODE-6803): kms proxy socket creates unhandled rejection

[nbbeeken]

Description

What is changing?

• Move KMS net socket creation into flagged path

Is there new documentation needed for these changes?

No

What is the motivation for this change?

The net socket was created unconditionally and in the finally block we destroy it which will reject the "willConnect" promise that is unhandled. Moving creation of the socket and the promise into a flagged path prevents this scenario.

Release Highlight

KMS Requests can cause unhandled

When using explicit encryption or automatic encryption, the driver makes requests to a Key Management System when to fetch key encryption keys. The driver supports connecting to a KMS provider through a Socks5 proxy. However, the socket used for the socks5 proxy was created in all circumstances, regardless of proxy configuration. This leads to unhandled rejection errors when closing the socket the driver attempts to clean up the unused socket.

With the changes in this release, the socket is only created if a proxy is configured and the any promises created for the proxy are properly handled.

Double check the following

• Ran npm run check:lint script
• Self-review completed using the steps outlined here
• PR title follows the correct format: type(NODE-xxxx)[!]: description
  • Example: feat(NODE-1234)!: rewriting everything in coffeescript
• Changes are covered by tests
• New TODOs have a related JIRA ticket