Expose epoch manager information

[mfornet]

Feature request
Create a host function to give access to epoch manager information. In particular I'm thinking about having a function that given a block_height returns the expected block_producer for that block. Notice that block_height can be from the future, as long as it is part of the current epoch and this information is already available.

Somehow related, is this change: #2504

Additional context
This can be achieved today without any protocol change, but it is inconvenient, by running a NEAR Light Client as a smart contract on top of NEAR (similar to the rainbow-bridge implementation). It is inconvenient because data must be relayed at least once per epoch.

[bowenwang1996]

Could you explain the use case here? Unless there is a strong reason, we usually do not consider adding new host functions. This is also related to #2745

[mfornet]

My specific use case is that I want to disallow some validators from being able to run my tx, by making the tx fail if the validator is in a blacklist.

Thinking about a more generic approach, instead of explicitly giving this info, we can expose the hash of the previous block. This is enough to proof anything that happened previously, in particular I think this is enough (with extra data) to proof who is the current block producer.

[bowenwang1996]

Should we revive the discussion on host function for block hash 😄

[stale]

This issue has been automatically marked as stale because it has not had recent activity in the last 2 months.
It will be closed in 7 days if no further activity occurs.
Thank you for your contributions.

[stale]

This issue has been automatically marked as stale because it has not had recent activity in the last 2 months.
It will be closed in 7 days if no further activity occurs.
Thank you for your contributions.