runtime-sdk/modules/evm: Add support for simulating CREATE

[kostko]

Story: oasisprotocol/oasis-web3-gateway#543 (comment)

Problem:

Performing an eth_call to simulate contract creation is currently not possible.

This is used by hardhat-ignition (a deterministic deployment framework) to determine if creating the contract will be possible.

In oasis web3 gateway the EstimateGas function calls either evm.Create or evm.Call depending on if the to field is empty. I initially made a workaround in oasis-web3-gateway by setting the to field to the zero address, however this will erroneously succeed (as calls to unknown addresses succeed so transfers can be made to previously unknown EOAs). So while that silences the error in hardhat-ignition the behavior is incorrect.

For the correct behavior the evm.SimulateCall function would be modified to handle contract creation with EVM semantics (no to address = create contract & run init code). The evm.SimulateCall function would make the address parameter optional. This would then have to be invoked with a signed query to faithfully replicate EVM semantics.

The initial workaround (setting to=0 ) is broken and shouldn't be used.

Example RPC call performed by hardhat-ignition :

{
  jsonrpc: '2.0',
  method: 'eth_call',
  params: [
    {
      value: '0x0',
      data: '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',
      from: '0xf39fd6e51aad88f6f4ce6ab8827279cfffb92266',
      nonce: '0x0',
      gas: '0x24dd3',
      gasPrice: '0x174876e800'
    },
    'pending'
  ],
  id: 12
}

Suggested modification to SimulateCallQuery struct:

/// Transaction body for simulating an EVM call.
#[derive(Clone, Debug, Default, cbor::Encode, cbor::Decode)]
#[cfg_attr(test, derive(PartialEq, Eq))]
pub struct SimulateCallQuery {
    pub gas_price: U256,
    pub gas_limit: u64,
    pub caller: H160,
    #[cbor(optional)]
    pub address: H160,
    pub value: U256,
    pub data: Vec<u8>,
}

Suggested modification in oasis-web3-gateway/rpc/eth/api.go :

    if args.Data != nil {
		input = *args.Data
	}
	if args.To == nil {
		if len(input) > 0 {
			// When simulating a contract deploy the To address may not be specified
			args.To = nil
		} else {
			return []byte{}, errors.New("to address not specified")
		}
	}

Suggested modification in runtime-sdk/modules/evm/src/lib.rs :

• Add logic from evm.Create tofn simulate_call
  • Or introduce a separate evm.SimulateCreate which can be invoked from oasis-web3-gateway instead of evm.Call

This PR

... solves this.

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[codecov]

Codecov Report

Attention: Patch coverage is 81.03448% with 11 lines in your changes are missing coverage. Please review.

Project coverage is 65.33%. Comparing base (da60d8d) to head (44eaec5).

Files	Patch %	Lines
runtime-sdk/modules/evm/src/lib.rs	76.59%	11 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1669      +/-   ##
==========================================
- Coverage   65.34%   65.33%   -0.01%     
==========================================
  Files         114      114              
  Lines        8365     8380      +15     
==========================================
+ Hits         5466     5475       +9     
- Misses       2899     2905       +6     

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[CedarMist]

It seems errors & reversions aren't being handled when simulating a contract creation via eth_call.

Oh, my bad, need to update oasis-web3-gateway to specify nil as the to field.

I need to test against updated oasis-web3-gateway

[CedarMist]

oasisprotocol/oasis-web3-gateway#546
oasisprotocol/sapphire-paratime#294