NewAddrBook creates a new address book.

NewPEXReactor creates new PEX reactor.

PexChannel is a channel for PEX messages.

PEXReactor handles PEX (peer exchange) and ensures that an adequate number of peers are connected to the switch.

PEXReactorConfig holds reactor specific configuration data.

AddrBook is an address book used for tracking peers so we can gossip about them to others and select peers to dial.

PexMessage is a primary type for PEX messages.