Struct locoBackend

tailcat.go:209–236

locoBackend is like tailscaled's LocalBackend, but crazier. It serves a similar purpose (to be the hub of the world) but there's no controlclient involved, because there's no control plane.

// but there's no controlclient involved, because there's
// no control plane.
type locoBackend struct {
	sys        tsd.System
	priv       key.NodePrivate
	pub        key.NodePublic
	addr       netip.Addr
	addrPrefix netip.Prefix
	ns         *netstack.Impl
	dm         *tailcfg.DERPMap
	logf       logger.Logf
	serverPub  key.NodePublic // non-zero if we're a client (server's public key)
	isServer   bool

	// discoPublic returns the node's disco public key, memoized to
	// avoid redoing the curve25519 derivation for every client that
	// joins.
	discoPublic func() key.DiscoPublic

	// onDERPRecv is called for non-disco DERP packets before the
	// peer map lookup. Set before createEngine.
	onDERPRecv func(regionID int, src key.NodePublic, pkt []byte) bool

	mu             sync.Mutex
	clients        map[key.NodePublic]*tailcfg.Node // for the server
	nm             *netmap.NetworkMap
	allowedClients map[key.NodePublic]bool // or nil map for all
	eps            []netip.AddrPort        // our current local UDP endpoints, sorted
	closeOnce      sync.Once
}

func (b *locoBackend) derpRegionID() int {
	if b.dm == nil {