address: sa.String(),
	}
}

// socket returns a network file descriptor that is ready for
// I/O using the fake network.
func socket(ctx context.Context, net string, family, sotype, proto int, ipv6only bool, laddr, raddr sockaddr, ctrlCtxFn func(context.Context, string, string, syscall.RawConn) error) (*netFD, error) {
	if raddr != nil && ctrlCtxFn != nil {
		return nil, os.NewSyscallError("socket", syscall.ENOTSUP)
	}

	// darwin, kernel version 11.3.0
	//	net.inet6.ip6.v6only=0 (overridable by sysctl or IPV6_V6ONLY option)
	// freebsd, kernel version 8.2
	//	net.inet6.ip6.v6only=1 (overridable by sysctl or IPV6_V6ONLY option)
	// linux, kernel version 3.0.0
	//	net.ipv6.bindv6only=0 (overridable by sysctl or IPV6_V6ONLY option)
	// openbsd, kernel version 5.0
	//	net.inet6.ip6.v6only=1 (overriding is prohibited)