Smart contract validation for ENS Subdomain Authentication (EIP-5131)
(Test run suggests (56,963 - 21,217) = 35,746 gas to do the check)
Discussion here: https://ethereum-magicians.org/t/eip-5131-ens-authentication-link/9458
Using truffle framework
npm install -g truffle
npm install -g ganache-cli
npm install
truffle compile
ganache-cli --accounts=1000 -l 20000000
truffle migrate
truffle test