Replayer should supply block specific context to transactions

[frankbraun]

@djsatok brought up the issue on Discord that smart contracts can use block.timestamp and if that doesn't match a replayed transaction will fail.

It's even worse then that, all of the following could potentially be used:

• block.coinbase
• block.timestamp
• block.number
• block.difficulty
• block.gaslimit
• hash = block.blockHash(blockNumber) (hash of the specific block, only valid for the 256 most recent blocks, excluding the current one)

See EVM Opcodes.

After discussion with @artob, taking into consideration that the EVM will now mostly be implemented as a smart contract, we agreed that the best approach would be to extend the near-web3-provider API with a something like Eth.send_raw_transaction_with_context. Similar to Eth.send_raw_transaction, but also passing in the necessary block context to execute the transaction within a test contract deployment of the EVM.

That way, in combination with issue #2, we should be able to replay all transactions of an Ethereum testnet to a NEAR EVM test deployment.

[alexauroradev]

@frankbraun , one important thing would be to guard Eth.send_raw_transaction_with_context, and most importantly, corresponding EVM contract method with a #feature[bully], which will be used only for stress-testing and will never be deployed in production environment.

[frankbraun]

@djsatok: Yes, absolutely. I think we should stress test on betanet that way, maybe on testnet (to be determined), but the corresponding functionality (in nearcore and near-web3-provider) should never be activated on mainnet.

[frankbraun]

The block context is now prepared by the replayer.

[frankbraun]

See also aurora-is-near/aurora-engine#2

[artob]

As described in aurora-is-near/aurora-engine#1 (comment) and aurora-is-near/aurora-engine#2 (comment), the EVM contract is now ready to begin accepting begin_chain and begin_block calls. The implementation of those functions is a work in progress, but they can be called already, unblocking the Bully to proceed calling them.