Is this a support request?

• This is not a support request

Is there an existing issue for this?

• I have searched the existing issues

Current Behavior

First off, love Headscale, it works great!

I think I found a bug in hostname handling.

When a client reports a hostname like "My-PC!", it fails ValidateHostname() and gets replaced with "invalid-xyz". Headscales code has a NormaliseHostname() function that would sanitize this to "my-pc".

The affected code paths are:

• ApplyHostnameFromHostInfo() hscontrol/types/node.go
• EnsureHostname() in hscontrol/util/util.go

Both use ValidateHostname() (reject if invalid), instead of NormaliseHostname() (sanitize and accept).

This seems like an oversight? The NormaliseHostname function exists but isn't being used.

Expected Behavior

Expected: Hostname "My-PC!" → sanitized to "my-pc"
Actual: Hostname "My-PC!" → rejected, becomes "invalid-abc123"

Steps To Reproduce

1. Register a node with hostname containing invalid characters:

On client with hostname "My-PC!"

tailscale up --login-server https://your-headscale-server

2. List nodes on server:
   headscale nodes list

3. Expected: Node appears as my-pc

4. Actual: Node appears as invalid-abc123

Environment

- Headscale version: v0.27.1
- Deployment: Docker
- OS: Ubuntu 24.04.3 LTS
- Docker: 29.0.2

Runtime environment

• Headscale is behind a (reverse) proxy
• Headscale runs in a container

Debug information

This is a code logic issue, so dont believe debug log is useful.