ClickHouse/dbms/src/Functions/FunctionFQDN.cpp

#include <Functions/IFunction.h>
#include <Functions/FunctionFactory.h>
#include <DataTypes/DataTypeString.h>
#include <Poco/Net/DNS.h>
#include <Core/Field.h>


namespace DB
{

class FunctionFQDN : public IFunction
{
public:
    static constexpr auto name = "FQDN";
    static FunctionPtr create(const Context &)
    {
        return std::make_shared<FunctionFQDN>();
    }

    String getName() const override
    {
        return name;
    }

    bool isDeterministic() const override { return false; }

    bool isDeterministicInScopeOfQuery() const override
    {
        return false;
    }

    size_t getNumberOfArguments() const override
    {
        return 0;
    }

    DataTypePtr getReturnTypeImpl(const DataTypes & /*arguments*/) const override
    {
        return std::make_shared<DataTypeString>();
    }

    void executeImpl(Block & block, const ColumnNumbers &, size_t result, size_t input_rows_count) override
    {
        block.getByPosition(result).column = block.getByPosition(result).type->createColumnConst(
            input_rows_count, Poco::Net::DNS::thisHost().name())->convertToFullColumnIfConst();
    }
};


void registerFunctionFQDN(FunctionFactory & factory)
{
    factory.registerFunction<FunctionFQDN>(FunctionFactory::CaseInsensitive);
    factory.registerFunction<FunctionFQDN>("fullHostName");
}

}