⤵️ZNSCurvePricer

ZNSCurvePricer

Implementation of the Curve Pricing, a module that calculates the price of a domain based on its length and the rules set by Zero ADMIN. This module uses a hyperbolic curve that starts at (baseLength; maxPrice) for all domains <= baseLength. Then the price is reduced using the price calculation function below. All prices after maxLength are fixed and equal the price at maxLength.

This contract is stateless as all the other Pricer contracts.

PERCENTAGE_BASIS

uint256 PERCENTAGE_BASIS

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

FACTOR_SCALE

uint256 FACTOR_SCALE

Multiply the entire hyperbola formula by this number to be able to reduce the curveMultiplier by 3 digits, which gives us more flexibility in defining the hyperbola function.

Canot be "0".

encodeConfig

function encodeConfig(struct IZNSCurvePricer.CurvePriceConfig config) external pure returns (bytes)

Encode a given CurvePriceConfig struct into bytes

Parameters

Name	Type	Description
config	struct IZNSCurvePricer.CurvePriceConfig	The CurvePriceConfig to encode into bytes

decodePriceConfig

function decodePriceConfig(bytes priceConfig) public pure returns (struct IZNSCurvePricer.CurvePriceConfig)

Decode bytes into a CurvePriceConfig struct

Parameters

Name	Type	Description
priceConfig	bytes	The bytes to decode

validatePriceConfig

function validatePriceConfig(bytes priceConfig) public pure

Validate the inputs for each variable in a price config

Will revert if incoming config is invalid

Parameters

Name	Type	Description
priceConfig	bytes	The price config to evaluate

getPrice

function getPrice(bytes parentPriceConfig, string label, bool skipValidityCheck) public pure 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
parentPriceConfig	bytes	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(bytes parentPriceConfig, uint256 price) public pure 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
parentPriceConfig	bytes	The price config in bytes of the parent domain under which fee is determined
price	uint256	The price to get the fee for

getPriceAndFee

function getPriceAndFee(bytes parentPriceConfig, string label, bool skipValidityCheck) external pure 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
parentPriceConfig	bytes	The price config in bytes of the parent domain under which fee is determined
label	string	The label of the subdomain candidate to get the price and fee for before/during registration
skipValidityCheck	bool

_checkLength

function _checkLength(bytes priceConfig) internal pure

_getFeeForPrice

function _getFeeForPrice(uint256 feePercentage, uint256 price) internal pure returns (uint256)

_validatePriceConfig

function _validatePriceConfig(struct IZNSCurvePricer.CurvePriceConfig config) internal pure

_getPrice

function _getPrice(struct IZNSCurvePricer.CurvePriceConfig config, uint256 length) internal pure returns (uint256)

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

Before we calculate the price, 6 different cases are possible:

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

2. baseLength is 0, which means prices for all domains = 0 (free).

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

4. length is greater than maxLength, which means a domain will cost price by fomula at maxLength

5. The numerator can be less than the denominator, which is achieved by setting a huge value for curveMultiplier or by decreasing the baseLength and maxPrice, which means all domains which are longer than baseLength will be free.

6. curveMultiplier is 0, which means all domains will cost maxPrice.

The formula itself creates an hyperbolic curve that decreases in pricing based on domain name length, base length, max price and curve multiplier. FACTOR_SCALE allows to perceive curveMultiplier as fraction number in regular formula, which helps to bend a curve of the price chart. 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

If the rawPrice calculated before truncation is less than the precisionMultiplier set, we return the precisionMultiplier as the price to avoid returning 0.

Parameters

Name	Type	Description
config	struct IZNSCurvePricer.CurvePriceConfig	The curve price config of the parent domain under which price is determined
length	uint256	The length of the domain name