[swarm] rewrite swarm DNS

[zelig]

@Arachnid

Expected behaviour

given a domain registered with the swarm dns
bzz:/// resolves correclty
the swarm/api calls likewise

Actual behaviour

• atm in the temp codebase the DNS is mocked out
• after with some discussion we decide to either forever or temporarily drop in-url versioning support as per registar.VersionedRegistrar andcommon/registrar/ethreg/

Resources

@Arachnid

• https://www.reddit.com/r/ethereum/comments/4dan2g/official_registrars/
• old frontier guide: https://ethereum.gitbooks.io/frontier-guide/content/registrar_services.html
• the EIP is: ERC: Default Ethereum Name Registrar EIPs#26
• have a look at Gav's orig registrar code: https://github.com/ethereum/dapp-bin/tree/master/registrar
• doc howto do ABI bindings from within go and generate stubs: https://github.com/ethereum/go-ethereum/wiki/Native-DApps:-Go-bindings-to-Ethereum-contracts
  • a hint how to use it : https://github.com/ethereum/go-ethereum/blob/swarm/common/chequebook/cheque.go
• the relevant swarm code entrypoint is: https://github.com/jaakmusic/go-ethereum/blob/jaak/swarm/api/dns.go
• mother issue: [swarm] swarm namereg rewrite #2048
• usage: https://github.com/ethersphere/swarm/wiki/swarm#bzz-domain-names-registration-resolution
• version support as per https://github.com/ethersphere/swarm/wiki/swarm#changes-versions-rollback is now dropped

[fjl]

@zelig side note: you can remove parts of the issue template if they are not appropriate

[zelig]

implemented in a series of ENS PRs:

• swarm/services/ens: Updated OpenRegistrar with new register logic #2879
• swarm: Add code to generate genesis JSON for swarm testnet #2912
• swarm: Rewrote ENS support for EIP137 #2903
• contracts/ens: Add ENS contract binding #2952