Function read_call_home_announce 

pub async fn read_call_home_announce<R>(
    reader: &mut R,
) -> Result<NodeId, CallHomeAnnounceError>
where
    R: AsyncRead + Unpin,

Relay side: find out whose socket this is.

Returns the announced id parsed as a NodeId. It is a claim, not a credential: the caller looks up that node’s configured access token and the handshake decides whether the claim was true.