Add Skynet support

[peterjan]

This PR adds support for resolving Skylinks, which are used to resolve content on the Skynet network, much like IPFS. The ENS protocol already supports using a sia://[skylink] hash as a content hash and is able to resolve it. Even Metamask's browser extension supports loading web apps hosted on Skynet via ENS, as well as Cloudflare's eth.link.

More information on Skynet can be found here.
More stats on the underlying decentralized storage network can be found here

Closes #2853

[ricmoo]

Please link to more info on the protocol and any stats on usage, adoption, etc. Also including examples of large projects using it is appreciated.

And please do not add dependencies. There is a base64 coder available in ethers already.

[peterjan]

Please link to more info on the protocol and any stats on usage, adoption, etc. Also including examples of large projects using it is appreciated.

Added more info.

And please do not add dependencies. There is a base64 coder available in ethers already.

The problem with "@ethersproject/base64" is that it does not support RFC 4648.
I made it URI safe manually to avoid having to update the base64 package but definitely open to suggestions on how to handle this better.

I couldn't find any unit testing but I manually verified it.
This content hash 0x90b2c6052000f25672e1c1400cc49c1473ee41ae013a926b7d4dc05d3d7c496a0701cf4fc8a9
should resolve to sia://IADyVnLhwUAMxJwUc-5BrgE6kmt9TcBdPXxJagcBz0_IqQ, which you can see here

Thank you for taking a look!

[dghelm]

Please link to more info on the protocol and any stats on usage, adoption, etc. Also including examples of large projects using it is appreciated.

Hello! In addition to PJ's edits mentioning Cloudflare and Metamask, making this PR was requested of us by ETH.LIMO who are a team trying to build a more decentralized resolver infrastructure.

In addition to working with ENS to get contenthash support, within the ETH ecosystem, 1inch also deploys to Skynet.

As for usage and context, the Sia storage network has been active since 2015, and currently stores 2.4 PB. (The network has never incentivized storage for empty or garbage data.) Skynet (launched in 2020) is built by the same team and is an extension of the protocol that pushes it into web-accessible data, with a current focus on decentralized front-ends.

[peterjan]

@ricmoo, should be ready for another 👀 - thanks in advance!

[ricmoo]

I don’t use Buffer in ethers (adds a lot of overhead in the browser builds), there is the arraying and hexlify functions for this, but don’t worry about that. Your PR is clear and concise enough for me to add this. :)

Do you have some test ENS names with skynet content hashes set?

[dghelm]

Do you have some test ENS names with skynet content hashes set?

Here are a few:
skynetlabs.eth
skynet-ens.eth
skysend.eth

[peterjan]

Your PR is clear and concise enough for me to add this. :)

Thanks for doing that @ricmoo we're excited to get this in!

[peterjan]

@ricmoo kind reminder :)

[eth-limo]

We're looking forward to this addition!

[ricmoo]

I’ve been focused on v6 for the last week, but will be going through the “on-deck” issues next week. :)

[dghelm]

HI @ricmoo -- please let me know if there's anything we can do from the Skynet side to support finishing up the PR!

[ricmoo]

Added in 5.6.7. Please comment on #2853 if there are any problems.

Thanks! :)