LabelUtils

Git Source

Title: DotNS Label Utilities Library

Canonical keccak labelhash and namehash helpers shared by every DotNS contract that derives node identifiers from user-supplied labels.

Exists so that the identical inline-assembly keccak sequences don't need to live in every controller, registrar, or resolver. Every caller that maps a label to an on-chain node goes through this library, which is the single source of truth for how a label hashes. The TLD is supplied by the caller (read from the protocol registry), so this library holds no network-specific constant.

Deliberate non-goals:

• Validation (single-label checks, min-length rules, availability): each caller owns its own validation policy alongside its own interface-declared errors. Centralising validation here would require centralising the error types, which breaks interface-level error ownership.
• Lowercase ASCII letters/digits/hyphen rules with hyphen-position constraints live in @custom:function StringUtils.isSingleLabel; this library treats the input as opaque bytes once a caller has run its own checks.

Note: security-contact: admin@parity.io

Functions

labelhash

Computes keccak256(bytes(label)) via memory-safe scratch space.

function labelhash(string calldata label) internal pure returns (bytes32 hash);

Parameters

Returns

labelhashMemory

Computes keccak256(bytes(label)) for a memory string.

Overload used by call sites that hold the label in memory (e.g. the registrar's transfer sync path reading _labels[tokenId]). Same semantics as @custom:function labelhash, different calldata shape.

function labelhashMemory(string memory label) internal pure returns (bytes32 hash);

Parameters

Returns

namehashUnder

Computes namehash(parent, labelhash) against an arbitrary parent.

Pass the TLD node (from the protocol registry) as parent for a top-level registration, or a subnode/PoP-namespace node for a nested name.

function namehashUnder(bytes32 parent, bytes32 labelhash_)
    internal
    pure
    returns (bytes32 node);

Parameters

Returns

deriveNode

Derives (labelhash, node) for a label under a given TLD node in one call.

Convenience combinator for registration flows: hashes the label exactly once and returns both identifiers callers need without recomputing.

function deriveNode(
    bytes32 tldNode,
    string calldata label
)
    internal
    pure
    returns (bytes32 hash, bytes32 node);

Parameters

Returns

stripTld

Strips the network's TLD suffix from a stored full name.

Returns the empty string when the input does not end in tld; callers treat an empty return as a "do not trust this record" signal.

function stripTld(
    string memory tldSuffix,
    string memory fullName
)
    internal
    pure
    returns (string memory label);

Parameters