transport: Support passing CID for linux vsock

[jalaziz]

Support passing the vsock CID explicitly as part of the listener address. This can be particularly useful in containerized environments where the /dev/vsock device is not available to lookup the CID.

In particular, we ran into this when trying to use gvproxy with AWS Nitro Enclaves on Kubernetes.

[cfergeau]

/lgtm

You mention AWS Nitro Enclaves, is this related to https://github.com/brave/nitriding-daemon ? Or do you need this in a different project?

[jalaziz]

/lgtm

You mention AWS Nitro Enclaves, is this related to https://github.com/brave/nitriding-daemon ? Or do you need this in a different project?

@cfergeau Indeed, we ran into this while testing out nitriding-daemon.

We were also testing AWS's vsock-proxy which works in a containers (but is outbound only). That's what led me to this.

Re-testing with this patch allowed everything to work without having to enable privileged containers or needing to have a device manager installed on the cluster that exposes /dev/vsock to the container.

[cfergeau]

/approve

[openshift-ci]

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