exemplary implementation of a fully decentralized ENS alternative

ENS_alternative.sol

// SPDX-License-Identifier: MIT

// exemplary implementation of a fully decentralized ENS alternative

// The ENS was described as partly centralized (root node controlled by ENS founders), while there is no fully decentralized solution yet. 
// Couldn't we simply create a smart contract for the registry which has no owners and provides name-register functionality via a public function? 
// To avoid spam and cluttering of the namespace, name-registrations have an expiration date and a cost depending on the duration (e.g. fixed 0.01Eth per month or dynamically adjusting with count of exiting registrations). 
// If we want to have a separation between "TLD"s and "subdomains", we can just have one of these smart contracts for each TLD and one for the root (which is read only). 

pragma solidity ^0.8.10;

contract ENS_alternative {
    mapping (string => address) public destinations;
    mapping (string => uint) public expiration_times;
    mapping (string => address) public owners;

    uint constant costMultiplyer = 42;

    function register(string calldata name, address destination) external payable {
        // only register if the name wasn't registered before or is expired or the owner want to change it
        if (expiration_times[name] == 0 || expiration_times[name] < block.timestamp || owners[name] == msg.sender) {
            destinations[name] = destination;
            expiration_times[name] = block.timestamp + msg.value * costMultiplyer;
            owners[name] = msg.sender;
        }
    }

    // TODO
    // * adjust costMultiplyer to some sane value or e.g. dynamically based on count of existing registrations
    // * use a read-one version of this contract for the root contract, where all "TLD"s are predefined. Each TLD is managed by one instance of this contract.
    // * don't void existing paid expiration_time when a name is updated by its owner.
    // * maybe remove old expired mappings
    // * maybe rather use a hash of the name for mapping instead of the name itself
    // * maybe more functionality
}