⤵️ZNSCurvePricer

Implementation of the Curve Pricing, module that calculates the price of a domain based on its length and the rules set by Zero ADMIN. This module uses an asymptotic curve that starts from maxPrice for all domains <= baseLength. It then decreases in price, using the calculated price function below, until it reaches minPrice at maxLength length of the domain name. Price after maxLength is fixed and always equal to minPrice.

PERCENTAGE_BASIS

uint256 PERCENTAGE_BASIS

Value used as a basis for percentage calculations, since Solidity does not support fractions.

priceConfigs

mapping(bytes32 => struct ICurvePriceConfig.CurvePriceConfig) priceConfigs

Mapping of domainHash to the price config for that domain set by the parent domain owner.

Zero, for pricing root domains, uses this mapping as well under 0x0 hash.

constructor

constructor() public

initialize

function initialize(address accessController_, address registry_, struct ICurvePriceConfig.CurvePriceConfig zeroPriceConfig_) external

Proxy initializer to set the initial state of the contract after deployment. Only Owner of the 0x0 hash (Zero owned address) can call this function.

Note the for PriceConfig we set each value individually and calling 2 important functions that validate all of the config's values against the formula:

• setPrecisionMultiplier() to validate precision multiplier

• _validateConfig() to validate the whole config in order to avoid price spikes

Parameters

Name	Type	Description
accessController_	address	the address of the ZNSAccessController contract.
registry_	address	the address of the ZNSRegistry contract.
zeroPriceConfig_	struct ICurvePriceConfig.CurvePriceConfig	a number of variables that participate in the price calculation for subdomains.

getPrice

function getPrice(bytes32 parentHash, string label, bool skipValidityCheck) public view returns (uint256)

Get the price of a given domain name

skipValidityCheck param is added to provide proper revert when the user is calling this to find out the price of a domain that is not valid. But in Registrar contracts we want to do this explicitly and before we get the price to have lower tx cost for reverted tx. So Registrars will pass this bool as "true" to not repeat the validity check. Note that if calling this function directly to find out the price, a user should always pass "false" as skipValidityCheck param, otherwise, the price will be returned for an invalid label that is not possible to register.

Parameters

Name	Type	Description
parentHash	bytes32	The hash of the parent domain under which price is determined
label	string	The label of the subdomain candidate to get the price for before/during registration
skipValidityCheck	bool	If true, skips the validity check for the label

getFeeForPrice

function getFeeForPrice(bytes32 parentHash, uint256 price) public view returns (uint256)

Part of the IZNSPricer interface - one of the functions required for any pricing contracts used with ZNS. It returns fee for a given price based on the value set by the owner of the parent domain.

Parameters

Name	Type	Description
parentHash	bytes32	The hash of the parent domain under which fee is determined
price	uint256	The price to get the fee for

getPriceAndFee

function getPriceAndFee(bytes32 parentHash, string label, bool skipValidityCheck) external view returns (uint256 price, uint256 stakeFee)

Part of the IZNSPricer interface - one of the functions required for any pricing contracts used with ZNS. Returns both price and fee for a given label under the given parent.

Parameters

Name	Type	Description
parentHash	bytes32	The hash of the parent domain under which price and fee are determined
label	string	The label of the subdomain candidate to get the price and fee for before/during registration
skipValidityCheck	bool

setPriceConfig

function setPriceConfig(bytes32 domainHash, struct ICurvePriceConfig.CurvePriceConfig priceConfig) public

Setter for priceConfigs[domainHash]. Only domain owner/operator can call this function.

Validates the value of the precisionMultiplier and the whole config in order to avoid price spikes, fires PriceConfigSet event. Only the owner of the domain or an allowed operator can call this function

This function should ALWAYS be used to set the config, since it's the only place where isSet is set to true. Use the other individual setters to modify only, since they do not set this variable!

Parameters

Name	Type	Description
domainHash	bytes32	The domain hash to set the price config for
priceConfig	struct ICurvePriceConfig.CurvePriceConfig	The new price config to set

setMaxPrice

function setMaxPrice(bytes32 domainHash, uint256 maxPrice) external

Sets the max price for domains. Validates the config with the new price. Fires MaxPriceSet event. Only domain owner can call this function.

maxPrice can be set to 0 along with baseLength or minPrice to make all domains free!

We are checking here for possible price spike at maxLength if the maxPrice values is NOT 0. In the case of 0 we do not validate, since setting it to 0 will make all subdomains free.

Parameters

Name	Type	Description
domainHash	bytes32
maxPrice	uint256	The maximum price to set

setMinPrice

function setMinPrice(bytes32 domainHash, uint256 minPrice) external

Sets the minimum price for domains. Validates the config with the new price. Fires MinPriceSet event. Only domain owner/operator can call this function.

Parameters

Name	Type	Description
domainHash	bytes32	The domain hash to set the minPrice for
minPrice	uint256	The minimum price to set in $ZERO

setBaseLength

function setBaseLength(bytes32 domainHash, uint256 length) external

Set the value of the domain name length boundary where the maxPrice applies e.g. A value of '5' means all domains <= 5 in length cost the maxPrice price Validates the config with the new length. Fires BaseLengthSet event. Only domain owner/operator can call this function.

baseLength can be set to 0 to make all domains cost maxPrice! This indicates to the system that we are currently in a special phase where we define an exact price for all domains e.g. promotions or sales

Parameters

Name	Type	Description
domainHash	bytes32	The domain hash to set the baseLength for
length	uint256	Boundary to set

setMaxLength

function setMaxLength(bytes32 domainHash, uint256 length) external

Set the maximum length of a domain name to which price formula applies. All domain names (labels) that are longer than this value will cost the fixed price of minPrice, and the pricing formula will not apply to them. Validates the config with the new length. Fires MaxLengthSet event. Only domain owner/operator can call this function.

maxLength can be set to 0 to make all domains cost minPrice!

Parameters

Name	Type	Description
domainHash	bytes32	The domain hash to set the maxLength for
length	uint256	The maximum length to set

setPrecisionMultiplier

function setPrecisionMultiplier(bytes32 domainHash, uint256 multiplier) public

Sets the precision multiplier for the price calculation. Multiplier This should be picked based on the number of token decimals to calculate properly. e.g. if we use a token with 18 decimals, and want precision of 2, our precision multiplier will be equal to 10^(18 - 2) = 10^16 Fires PrecisionMultiplierSet event. Only domain owner/operator can call this function.

Multiplier should be less or equal to 10^18 and greater than 0!

Parameters

Name	Type	Description
domainHash	bytes32
multiplier	uint256	The multiplier to set

setFeePercentage

function setFeePercentage(bytes32 domainHash, uint256 feePercentage) public

Sets the fee percentage for domain registration.

Fee percentage is set according to the basis of 10000, outlined in PERCENTAGE_BASIS. Fires FeePercentageSet event. Only domain owner/operator can call this function.

Parameters

Name	Type	Description
domainHash	bytes32	The domain hash to set the fee percentage for
feePercentage	uint256	The fee percentage to set

setRegistry

function setRegistry(address registry_) external

Sets the registry address in state.

This function is required for all contracts inheriting ARegistryWired.

_getPrice

function _getPrice(bytes32 parentHash, uint256 length) internal view returns (uint256)

Internal function to calculate price based on the config set, and the length of the domain label.

Before we calculate the price, 4 different cases are possible:

1. maxPrice is 0, which means all subdomains under this parent are free

2. baseLength is 0, which means we are returning maxPrice as a specific price for all domains

3. length is less than or equal to baseLength, which means a domain will cost maxPrice

4. length is greater than maxLength, which means a domain will cost minPrice

The formula itself creates an asymptotic curve that decreases in pricing based on domain name length, base length and max price, the result is divided by the precision multiplier to remove numbers beyond what we care about, then multiplied by the same precision multiplier to get the actual value with truncated values past precision. So having a value of 15.235234324234512365 * 10^18 with precision 2 would give us 15.230000000000000000 * 10^18

Parameters

Name	Type	Description
parentHash	bytes32
length	uint256	The length of the domain name

_validateConfig

function _validateConfig(bytes32 domainHash) internal view

Internal function called every time we set props of priceConfigs[domainHash] to make sure that values being set can not disrupt the price curve or zero out prices for domains. If this validation fails, the parent function will revert.

We are checking here for possible price spike at maxLength which can occur if some of the config values are not properly chosen and set.

_authorizeUpgrade

function _authorizeUpgrade(address newImplementation) internal view

To use UUPS proxy we override this function and revert if msg.sender isn't authorized

Parameters

Name	Type	Description
newImplementation	address	The new implementation contract to upgrade to.