Multi-chain address resolution guidelines

Resolving a chain address (for example, a Bitcoin address) associated to a domain consist of 4 steps:

1. Obtain the identifier of the domain.

   Use namehash algorithm

2. Get the domain’s resolver contract.

   Use resolver(bytes32)

3. Detect if contract supports chainAddr(bytes32,bytes4) interface via ERC-165 interface detection.

   Use supportsInterface(bytes4) with interface ID: 0x8be4b5f6

   ERC-165 spec

4. Query for address resolution.

   Use chainAddr(bytes32,bytes4) with the domain identifier and the chain hexa identifier

   chainAddr(bytes32,bytes4) spec

function getAddr(domain, chain) {
  const node = namehash(domain)
  const resolver = rns.resolver(node)
  if (!resolver.supportsInterface('0x8be4b5f6'))
    throw;
  return resolver.chainAddr(node, chain);
}