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Interface Compliance

Engineer/Developer Security Specialist
Written by:
Ghadi Mhawej - JustaLab

Verify Resolver Interface Support

  • Always check if a resolver supports your target interface using EIP-165
  • Call supportsInterface() before attempting to use specific resolver methods
  • Implement graceful fallbacks when interfaces aren't supported
  • Cache interface support results to minimize redundant on-chain calls

Rationale: ENS resolvers can implement various interfaces, each providing different functionality (addresses, text records, content hashes, etc.). Not all resolvers implement all interfaces, so checking interface support before calling specific methods prevents failed transactions and improves reliability. This verification step is especially important as the ENS ecosystem evolves and new resolver interfaces are introduced. Without proper interface verification, applications may fail when encountering resolvers with limited functionality or custom implementations.

Signal Supported Interfaces in Custom Resolvers

  • When writing custom resolvers, properly implement EIP-165
  • Signal all supported interfaces via supportsInterface()
  • Document which interfaces your resolver supports
  • Consider incremental implementation of interfaces based on user needs

Rationale: Implementing EIP-165 interface detection allows other contracts and applications to programmatically discover what functionality your resolver supports. This promotes interoperability and ensures your custom resolver can seamlessly integrate with the broader ENS ecosystem. Proper interface signaling is not just a technical requirement but a key element of good blockchain protocol citizenship. Without it, other contracts and applications can't reliably determine the capabilities your resolver offers, leading to poor user experiences and potential security risks.

Stay Updated with ENS Improvement Proposals (ENSIPs)

  • Regularly monitor the ENS GitHub repository for new ENSIPs
  • Participate in ENSIP discussions to provide implementer feedback
  • Implement support for new ENSIPs after they reach "Final" status
  • Plan for deprecation of older interfaces as specified by ENSIPs
  • Test implementations against the reference implementations provided in ENSIPs

Rationale: The ENS protocol evolves through the ENSIP process, which introduces new interfaces, standards, and recommended practices. Staying current with these proposals ensures your implementation remains compatible with the broader ecosystem and can leverage new functionality as it becomes available. ENSIPs often address security vulnerabilities, improve user experience, or add valuable new features that users will come to expect. Implementers who track and promptly adopt new ENSIPs gain competitive advantages while contributing to the overall health and advancement of the ENS ecosystem.