Optionally only perform dial-backs on peers that are observed at a global ip-address.
This is relevant when multiple peers are in the same local network, in which case a peer could incorrectly assume themself to be public because a peer in the same local network was able to dial them. Thus servers should reject dial-back requests from clients with a non-global IP address, and at the same time clients should only pick connected peers as servers if they are global.
Behind a config flag (enabled by default) to also allow use-cases where AutoNAT is needed within a private network.
This commit adds a behaviour protocol that implements the AutoNAT specification.
It enables users to detect whether they are behind a NAT. The Autonat Protocol
implements a Codec for the Request-Response protocol, and wraps it in a new
Network Behaviour with some additional functionality.
Co-authored-by: David Craven <david@craven.ch>
Co-authored-by: Max Inden <mail@max-inden.de>
