Add DNS Support

[n3r0-ch]

Add DNS Support instead of only supporting Namecoin.

I suggest to use TXT records similar to the following example:

subdomain        IN      TXT    "zero=1Gfey7wVXXg1rxk751TBTxLJwhddDNfcdp"

[HelloZeroNet]

Yeah its a good idea for a plugin, I already made some experiment earlier when i wanted to implement .bit support using http://www.opennicproject.org/
Need more experimenting, not sure if its possible using http://pydns.sourceforge.net/ & Tor network

[n3r0-ch]

Added pullrequest #111

[HelloZeroNet]

The problem is it relies on dns servers, so the sites will not works offline. Cache required to make it work without internet connection example at dnschain plugin.
I don't really want to add more external dependencies, but pydns is a pure-python module, so distributing in the lib dir could work.

[koalalorenzo]

I think this will help a lot! And you can make the DNS support as a "fallback" in case other solutions are failing, to make it less centralised @HelloZeroNet and probably there is a solution to make it work offline as well.

The trouble with DNS is that it's not secure and is also quite centralized.

[filips123]

@HelloZeroNet Any progress here? Will classic DNS be supported?

Even if DNS isn't so decentralized, it would be good if it is supported.
You could use cache to avoid offline problems. And there are probably also solutions for other problems with it.

And for DNS servers, it should probably use OpenNIC by default (because it is "open and democratic alternative DNS root"), but it should be configurable by user.

[filips123]

IPFS also support similar thing.

You can add TXT record that points to IPFS file hash (dnslink=/ipns/<your-hash>). File is then accessible from ipfs-proxy.com/your-domain.com.

In addition, if you also create CNAME record that points to public IPFS proxy (217.182.195.23 for gateway.ipfs.io), file is also accessible directly from your-domain.com).

This would also be extremely useful for ZeroNet. Site owner would then only need to create TXT record with ZeroNet address and CNAME record that points to (trusted) ZeroNet public proxy or local ZeroNet instance and site would be accessible directly from classic domain.

[ValdikSS]

Note that implementing TXT query only on the main domain is not a very good idea since that prevents using CNAME records.

IPFS introduces _dnslink prefix and queries TXT record like this:
get TXT of _dnslink.example.com
if that failed, get TXT of example.com

That way you can setup CNAME on example.com and additional TXT record on _dnslink.example.com.

[filips123]

@ValdikSS Yes, that is how I want to be implemented. With this, it should be also possible to handle subdomains (_dnslink.subdomain.example.com), right?

[ValdikSS]

@filips123 Yes, should be no problems with subdomains.

[filips123]

@ValdikSS It appears that DNSLink, which is used by IPFS, is already some kind of standard. It also supports linking other types different from IPFS.

So, instead of reinventing the wheel with a custom type of DNS record, ZeroNet should just use DNSLink. ZeroNet records should use the same names and structure as IPFS's, just record's content should be dnslink=/zeronet/1HeLLo4uzjaLetFx6NH3PMwFP3qbRbTf3D.