StringUtils

Git Source

Title: String Utilities Library

Provides string manipulation utilities for DotNS contracts.

Extends OpenZeppelin's Strings library with additional UTF-8 and conversion helpers.

Note: security-contact: admin@parity.io

Constants

MIN_LITE_SUFFIX_DIGITS

Minimum number of trailing digits required in a lite-person PoP label suffix.

Matches pallet_resources::MIN_LITE_USERNAME_DIGITS to avoid drift between what People Chain emits and what DotNS accepts.

uint256 internal constant MIN_LITE_SUFFIX_DIGITS = 2

MAX_DNS_LABEL_OCTETS

Maximum number of octets in a single DNS label.

RFC 1035 caps each label at 63 octets. Enforced inside @custom:function _isDnsLabel so every public validator (@custom:function isSingleLabel, @custom:function isNamePath,

Note: function: isSingleDotLiteLabel, @custom:function isLitePersonLabel) inherits the bound and oversized labels never reach the registrar.

uint256 internal constant MAX_DNS_LABEL_OCTETS = 63

Functions

strlen

Computes the character length of a UTF-8 encoded string.

Counts Unicode code points, not bytes. Handles multi-byte UTF-8 sequences:

• 1 byte: 0x00-0x7F (ASCII)
• 2 bytes: 0xC0-0xDF
• 3 bytes: 0xE0-0xEF
• 4 bytes: 0xF0-0xF7
• 5 bytes: 0xF8-0xFB (rare, outside Unicode standard)
• 6 bytes: 0xFC-0xFD (rare, outside Unicode standard)

function strlen(string memory value) internal pure returns (uint256 len);

Parameters

Returns

isSingleLabel

Validates that s is a single canonical DNS label.

Lowercase ASCII letters, digits, and hyphen only; hyphen may not be the first or last character; length must be in (0, MAX_DNS_LABEL_OCTETS]. No dots allowed; use

Note: function: isNamePath for dotted forms. Mirrors the label rules enforced at the registrar.

function isSingleLabel(string calldata value) internal pure returns (bool isValid);

Parameters

Returns

isSingleLabelMemory

Memory-location helper for @custom:function isSingleLabel, used where the candidate label is produced by an upstream string transformation (e.g. the output of

Note: function: stripDigits) so callers do not need a calldata round-trip.

function isSingleLabelMemory(string memory value) internal pure returns (bool isValid);

Parameters

Returns

stripDots

Removes dot separators from a dotted label.

Used by the PoP gateway boundary to normalise user-facing name.path input into the flat label expected by pricing and minting.

function stripDots(string calldata value) internal pure returns (string memory stripped);

Parameters

Returns

isSingleDotLiteLabel

Validates the gateway-facing lite input shape: stem.suffix.

Requires exactly one dot separator. The left segment must be a canonical DNS label and the right segment must be digits-only with exactly

Note: constant: MIN_LITE_SUFFIX_DIGITS characters.

function isSingleDotLiteLabel(string calldata value) internal pure returns (bool isValid);

Parameters

Returns

isLitePersonLabel

Validates the lite-person PoP label format: <stem><digits>.

A lite-person label is a single DNS label whose trailing characters are digits, with at least @custom:constant MIN_LITE_SUFFIX_DIGITS digits at the tail. It Mirrors @custom:pallet pallet_resources::MIN_LITE_USERNAME_DIGITS. Lite and public registrations share the same namespace; the gateway strips any separator before calling so the on-chain label is a flat DNS label (e.g. alice42). First-to-mint wins at the ERC721 layer; cross-flow priority on the stripped stem is arbitrated by @custom:function IPopRules.reserveBaseNameForPop. Keeping a single namespace avoids the ambiguity dotli/dweb would otherwise see between andrew.47 (lite) and andrew owning 47 as a subname.

Note: constant: MIN_LITE_SUFFIX_DIGITS trailing digits.

function isLitePersonLabel(string calldata value) internal pure returns (bool isValid);

Parameters

Returns

isLitePersonLabelMemory

Memory-location helper for @custom:function isLitePersonLabel, used by controller-side normalisation paths.

Note: constant: MIN_LITE_SUFFIX_DIGITS trailing digits.

function isLitePersonLabelMemory(string memory value) internal pure returns (bool isValid);

Parameters

Returns

_isLitePersonLabel

function _isLitePersonLabel(bytes memory raw) private pure returns (bool isValid);

isNamePath

Validates that s is a dot-separated path of canonical DNS labels.

Each segment between dots must satisfy @custom:function isSingleLabel. Empty segments (leading, trailing, or consecutive dots) fail. Used when callers submit multi-label paths (e.g. alice.dot) rather than bare labels.

function isNamePath(string calldata value) internal pure returns (bool isValid);

Parameters

Returns

_isDnsLabel

function _isDnsLabel(
    bytes memory label,
    uint256 start,
    uint256 end
)
    private
    pure
    returns (bool isValid);

uintToString

Converts a uint256 to its decimal string representation.

Wraps OpenZeppelin's Strings.toString().

function uintToString(uint256 value) internal pure returns (string memory);

Parameters

Returns

addressToHex

Converts an address to its checksummed hexadecimal string representation.

Wraps OpenZeppelin's Strings.toHexString(). Returns lowercase hex with "0x" prefix.

function addressToHex(address account) internal pure returns (string memory);

Parameters

Returns

bytes32ToString

Converts a bytes32 value to a string, treating it as a null-terminated ASCII string.

Reads bytes until the first null byte (0x00) or end of bytes32. Useful for converting short strings stored in bytes32 back to string type.

function bytes32ToString(bytes32 _bytes32) internal pure returns (string memory);

Parameters

Returns