ForkDigest command based on Slot

[tdahar]

Motivation

The Ethereum Ecosystem is showing interest in the peers that are online in the distributed network. However, the peer-to-peer network is open to anyone to use it, so nodes running different chains could overlap. We use the ForkDigest to differentiate which chain a node follows: mainnet, prater, sepolia... Not only that, the ForkDigest is a result of computing the genesis of the chain with the current fork version, so we could even detect which fork the node is following.
See more details here:

• https://eth2book.info/capella/part3/helper/misc/#compute_fork_digest
• https://github.com/ethereum/consensus-specs/blob/v1.3.0/specs/phase0/p2p-interface.md#why-do-we-not-form-enrs-and-find-peers-until-genesis-blockstate-is-known

Description

As ForkDigest is computed from the genesis root and the current fork version, it would be very nice to have a command to know which fork_digest represents a network (mainnet, goerli, sepolia...) in a specific fork version (Altair, Capella...). Armiarma already computes this for the current head of a given node, but it would be awesome to do this with past forks, in order to check if there are nodes in the network left behind in a previous fork.

For this, it would be nice to have a small command that could receive two parameters:

• Beacon Node URL
• Slot or Epoch

Then, the tool could request the Genesis and the fork version at the given slot, then output the fork_digest.
Example:
./eth-crawler fork_digest http://localhost:5052 2375711

The given slot is the last slot of the first epoch in Altair.

[cortze]

hey @tdahar , this is a really cool idea!
To give some context on the crawler, there is already this functionality that can request all the necessary info from a local beacon node to later compose the fork_digest.

armiarma/pkg/networks/ethereum/remoteendpoint/utils.go

Line 17 in 1f69e06

func GetForkDigetsOfEth2Head(ctx context.Context, infCli *InfuraClient) (common.ForkDigest, error) {

So it seems to be a pretty straight forward implementation