Enumeration RelayTunnelEvent

Phase of a tunnel message, describing what the payload means.

• connect – originator asks the peer to dial the destination and open a new tunneled connection.
• connected – peer confirms the destination has been dialed.
• connectFailed– peer reports the dial attempt failed.
• data – raw bytes flowing between the two ends of a connection.
• windowUpdate – receiver returns flow-control credit to the sender.
• close – one end has closed the connection.