Every diagnostic command nebula has was reachable through exactly one door:
the built-in ssh debug server. That server is off by default, and turning it
on means generating a host key, writing an sshd block with authorized public
keys, and SIGHUPing the daemon. That is a lot of ceremony to answer "what
version is this node running".
Nebula now serves the same commands over a local unix socket, enabled by
default, and `nebula ctl <command>` runs them. The socket lives in a 0700
directory so filesystem permissions are the access control; no keys, nothing
on the network. Failing to create it is logged and never blocks startup.
The command registry was already transport neutral, so this is mostly new
transport rather than new commands:
- diag/ holds the registry, dispatch, writer and wire protocol, moved out
of sshd because none of it was ever about ssh. sshd and ctl.go dispatch
against one shared registry.
- commands.go holds every command implementation, moved out of ssh.go
(which was 85% not ssh) and renamed off the ssh prefix. Adding a command
there makes it available over both transports.
- ssh.go keeps only host keys, authorized users, and the listen address.
- ctl.go supervises the socket, following the statsServer lifecycle shape.
The wire protocol frames the response rather than terminating it, because
print-cert -raw and list-hostmap -json both emit arbitrary bytes that no
sentinel could safely delimit. argv travels as a list so quoting survives.
Exit statuses are real: 0, 2 for usage, 127 for an unknown command.
Two things fall out. The ssh console now reports a real exit status instead
of a hardcoded zero, so `ssh host list-hostmap` is scriptable too. And eight
command callbacks that silently returned nil on a flags type mismatch now
report it, which the exit status makes visible.
Windows is a stub returning a clear "not supported" until it gets a named
pipe with a security descriptor; iOS and Android are never enabled, having no
daemon for a CLI to attach to.
Breaking for embedders of the sshd package: NewSSHServer takes a
*diag.Registry, SSHServer.RegisterCommand is gone in favor of registering on
that registry, and the command types live in diag rather than sshd.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_014fya5fTXGiwX72FUmoL9y3
These new helpers make the code a lot cleaner. I confirmed that the
simple helpers like `atomic.Int64` don't add any extra overhead as they
get inlined by the compiler. `atomic.Pointer` adds an extra method call
as it no longer gets inlined, but we aren't using these on the hot path
so it is probably okay.
This change fixes all of the known data races that `make smoke-docker-race` finds, except for one.
Most of these races are around the handshake phase for a hostinfo, so we add a RWLock to the hostinfo and Lock during each of the handshake stages.
Some of the other races are around consistently using `atomic` around the `messageCounter` field. To make this harder to mess up, I have renamed the field to `atomicMessageCounter` (I also removed the unnecessary extra pointer deference as we can just point directly to the struct field).
The last remaining data race is around reading `ConnectionInfo.ready`, which is a boolean that is only written to once when the handshake has finished. Due to it being in the hot path for packets and the rare case that this could actually be an issue, holding off on fixing that one for now.
here is the results of `make smoke-docker-race`:
before:
lighthouse1: Found 2 data race(s)
host2: Found 36 data race(s)
host3: Found 17 data race(s)
host4: Found 31 data race(s)
after:
host2: Found 1 data race(s)
host4: Found 1 data race(s)
Fixes: #147Fixes: #226Fixes: #283Fixes: #316
