func (*endpoint) Capabilities() stack.LinkEndpointCapabilities {
	return stack.CapabilityRXChecksumOffload | stack.CapabilityTXChecksumOffload | stack.CapabilitySaveRestore | stack.CapabilityLoopback
}
Capabilities implements stack.LinkEndpoint.Capabilities. Loopback advertises
itself as supporting checksum offload, but in reality it's just omitted.
package loopback
import (
	"github.com/google/netstack/tcpip"
	"github.com/google/netstack/tcpip/buffer"
	"github.com/google/netstack/tcpip/header"
	"github.com/google/netstack/tcpip/stack"
)
type endpoint struct {
	dispatcher stack.NetworkDispatcher
}
func New() stack.LinkEndpoint {
	return &endpoint{}
}
func (e *endpoint) Attach(dispatcher stack.NetworkDispatcher) {
	e.dispatcher = dispatcher
}
func (e *endpoint) IsAttached() bool {
	return e.dispatcher != nil
}
func (*endpoint) MTU() uint32 {
	return 65536
}