DevCon4 ENS technical integration workshop

Transcript

1. Ethereum Name Service https://ens.domains DevCon4
2. Speakers @makoto_inoue @_jefflau
3. Also known for...
4. Assistant @nicksdjohnson
5. Agenda - 1. Intro & What can you do with ENS? - 2. ENS contracts and API overview - 3. Issuing subdomain to new users for your dapp
6. Intro: What is ENS?
7. What is ENS? 0xfdb33f8ac7ce72d7d4795 dd8610e323b4c122fbb
8. What is ENS? arachnid.eth
9. What is ENS?
10. What is ENS?
11. More than just names ENS names contracts and accounts, but also… • Swarm & IPFS records • Legacy DNS records - IP addresses, mail exchangers • Stores contract interfaces
12. More than just .eth
13. [Bonus] Free .luxe domains First 500 .luxe domains Marketing@mmx.co Subject: Devcon
14. What can you do with your ENS?
15. 1. Name your address (aka lookup)
16. 2. Show names (aka reverse lookup)
17. Custom swags?
18. https://swag.ethereum.org/collections/tees/products/custom-ens-shir t
19. 3. Give subdomain
20. 999. NFT everything! ensnifty.com
21. ENS contract and API overview
22. ENS Architecture
23. Resolving a name
24. Contract MyResolver { address me; function MyResolver() { me = msg.sender; } function addr(bytes32 node) constant returns (address) { return me; } } ENS by example: Resolvers
25. Using ENS from Javascript import ENS from `ethereum-ens’ const ens = new ENS(web3);
26. Looking up names const address = await ens.resolver(‘arachnid.eth’).addr();
27. Reverse resolution const addr = ‘0x112234455...’ const name = await ens.reverse(‘0x112234455...’).name() //for security const forward = await ens.resolver(name) if(addr === forward){ …. }
28. Setting up reverse resolution reverseRegistrar.setName(‘jefflau.eth’)
29. Contracts in web3 var testContract = web3.eth.contract( [{"constant":true,"inputs":...}]) var test = testContract.at(“0x0904dac3347ea47d208f...”);
30. Contracts in ENS const contract = ens.resolver(‘arachnid.eth’).instance(); contract.myContractMethod()
31. Issuing subdomain to new users for your dapp
32. Signup flow example Make sure - User is on the right network - Metamask is unlocked
33. Getting ENS subdomain Check if the ENS subdomain already exists - If yes, then check if it is owned by the address currently on metamask - If yes then its a sign in, make them sign a message to prove they actually hold the acount they are signing up for. If it doesnt exist then they can have it!
34. Sign up Subdomain transactions are sent asynchronously so users can start using the platform instantly
35. Verify account Signing a message to verify they hold the account A nounce to prevent replay attacks
36. Account Users are logged in regardless of the status of transactions. (UX comment) Since Zinc sends the transactions and the messages are verified on chain, they are also verified off chain to prevent sending transactions which are guaranteed to fail.
37. The actual code of zinc
38. Contract MyAweSomeApp { function register(bytes32 label) public { bytes32 node = getNode(label); require(ens.owner(node) == address(0)) ens.setSubnodeOwner(rootNode, label, this); ens.setResolver(node, resolver); resolver.setAddr(node, msg.sender); ens.setOwner(node, msg.sender); } } The code
39. Contract MyAweSomeApp { function register(bytes32 label) public { bytes32 node = getNode(label); require(ens.owner(node) == address(0)) ens.setSubnodeOwner(rootNode, label, this); ens.setResolver(node, resolver); resolver.setAddr(node, msg.sender); ens.setOwner(node, msg.sender); } } The code web3.utils.sha3(“makoto”)
40. Contract MyAweSomeApp { function register(bytes32 label) public { bytes32 node = getNode(label); require(ens.owner(node) == address(0)) ens.setSubnodeOwner(rootNode, label, this); ens.setResolver(node, resolver); resolver.setAddr(node, msg.sender); ens.setOwner(node, msg.sender); } } The code keccak256(abi.encodePacked(“yourdomain.eth”, label))
41. Contract MyAweSomeApp { function register(bytes32 label) public { bytes32 node = getNode(label); require(ens.owner(node) == address(0)) ens.setSubnodeOwner(rootNode, label, this); ens.setResolver(node, resolver); resolver.setAddr(node, msg.sender); ens.setOwner(node, msg.sender); } } The code web3.utils.sha3(“makoto.yourdomain.eth”)
42. Contract MyAweSomeApp { function register(bytes32 label) public { bytes32 node = getNode(label); require(ens.owner(node) == address(0)) ens.setSubnodeOwner(rootNode, label, this); ens.setResolver(node, resolver); resolver.setAddr(node, msg.sender); ens.setOwner(node, msg.sender); } } The code Check the name is not taken yet
43. Contract MyAweSomeApp { function register(bytes32 label) public { bytes32 node = getNode(label); require(ens.owner(node) == address(0)) ens.setSubnodeOwner(rootNode, label, this); ens.setResolver(node, resolver); resolver.setAddr(node, msg.sender); ens.setOwner(node, msg.sender); } } The code Set the contract to own “makoto.yourdomain.eth”
44. Contract MyAweSomeApp { function register(bytes32 label) public { bytes32 node = getNode(label); require(ens.owner(node) == address(0)) ens.setSubnodeOwner(rootNode, label, this); ens.setResolver(node, resolver); resolver.setAddr(node, msg.sender); ens.setOwner(node, msg.sender); } } The code Set the default resolver to “makoto.yourdomain.eth”
45. Contract MyAweSomeApp { function register(bytes32 label) public { bytes32 node = getNode(label); require(ens.owner(node) == address(0)) ens.setSubnodeOwner(rootNode, label, this); ens.setResolver(node, resolver); resolver.setAddr(node, msg.sender); ens.setOwner(node, msg.sender); } } The code Set the sender address to “makoto.yourdomain.eth”
46. Contract MyAweSomeApp { function register(bytes32 label) public { bytes32 node = getNode(label); require(ens.owner(node) == address(0)) ens.setSubnodeOwner(rootNode, label, this); ens.setResolver(node, resolver); resolver.setAddr(node, msg.sender); ens.setOwner(node, msg.sender); } } The code Give the ownership of the node to the sender
47. ENS Design considerations
48. Somethings were missing in previous slides
49. Hint 1
50. - Reverse record can be only set by the owner of the address - You can still have a button on dapp to call `reverseRegistrar.setName(‘jefflau.eth’)` to set reverse record. - However, should your Dapp enforce setting reverse record as it may override previous setting? 1. Assigning reverse record
51. Hint 2
52. 2. Assigning subdomain
53. 2. Assigning subdomain
54. 2. Assigning subdomain
55. 2. Assigning subdomain
56. 2. Assigning subdomain cost gas Solutions - Dapp pay for the gass (Gitcoin/zinc) - Make it optional (Gitcoin) - Do nothing (Kickback)
57. Hint 3
58. Hint 3
59. Hint 3
60. Solidity 101 FAIL
61. https://medium.com/the-ethereum-name-service https://docs.ens.domains/en/latest http://github.com/ensdomains References
62. Questions?