Support for multiple devp2p capabilities

[akirillo]

Describe the feature

The current implementation of p2p streams only supports a single capability, because we only support eth and are compatible with both eth/66 and eth/67.

We should implement support for multiple capabilities using message ID multiplexing.

Additional context

We already have some of the logic for message ID multiplexing via the calculation of message ID offsets, but we can't yet fully support multiple capabilities. Currently, the EthStream directly wraps the P2PStream, assumes eth is the only supported capability and just subtracts the offset for every message in the stream before decoding.

To support multiple capabilities we'd need to create a new Stream type (which might need to implement Future or something similar) to go on top of P2PStream, containing its capability.

The P2PStream would still send pings and handle pongs, but now contain a map of capabilities to their respective stream / channel. It would determine the intended capability (based on the shared capabilities / offsets), and send the message to that capabilities' stream. Each stream would be responsible for containing the offset for that stream and would only increment / decrement message IDs.

[mridullpandey]

Hello @akirillo Sir, Is this done!
If not I would love to take this

[akirillo]

Hello @akirillo Sir, Is this done!

If not I would love to take this

Hi hi @mridullpandey, nope not done, I'm handling #908 right now so feel free to take this!

[gakonst]

@mridullpandey let us know if you'll have some capacity on this; else can unassign^^

[anukul]

Hi! I'd like to try this issue, if available.

[gakonst]

@mridullpandey do you intend to take this? else we can give to @anukul!

[mridullpandey]

Yes for now i'm working on other issue so we can give it to @anukul

[bharath-123]

hey @anukul are you still on this?

[bharath-123]

would love to take it up if not

[anukul]

hey @bharath-123 i haven't gotten around to finishing this one, go for it.

[bharath-123]

Thanks for assigning @gakonst ! Will take a look at this

[distributedstatemachine]

@bharath-123 are you still working on this ? If not i would love to take it on

[onbjerg]

Still relevant @mattsse @Rjected?

[gakonst]

Yes we don't have support for eg adding snap or les.

[mattsse]

we support this now