System router: flexible optimistic period, multicall

[ChiTimesChi]

Description

SystemRouter contract is revisited to introduce the chain agnostic system calls. This also includes the ability to batch such calls in a package, where either all calls succeed or none do (multicall). Multicalls are currently only possible to a single destination chain, otherwise the execution invariant doesn't hold.

System call: sending

Any system contract is able to call another system contract on any chain without knowing its address. All that's needed for a call is:

• Domain of chain where call is supposed to happen (local domain for call on the local chain)
• Optimistic period that is required for executing this call (ignored for calls on the local chain)
• Which system contract to call, i.e. Origin, Destination, etc (no exact address knowledge is required)
• Data payload for the call

This is possible by SystemRouter storing all system addresses for the chain where it's deployed and sending system messages to the system routers on remote chains (which will handle the routing on destination chain).

System call: receiving

Regardless on what chain the recipient is located, when the call is routed to them, they will receive the data payload with following appended information:

• Domain of chain where call originated (local domain for call on the local chain)
• Which system contract originated the system call, i.e. Origin, Destination, etc (no exact address knowledge is required)
• Timestamp when the merkle root (used for executing the cross-chain message) was submitted to Destination (block.timestamp for local chain calls)

sanguine/packages/contracts-core/contracts/system/SystemRouter.sol

Lines 230 to 245 in 3d61027

	function _formatCalldata(SystemEntity _caller, bytes memory _data)
	internal
	view
	returns (bytes memory)
	{
	/**
	* @dev Payload for contract call is:
	* ====== ENCODED ON ORIGIN CHAIN ======
	* 1. Function selector and params (_data)
	* 2. (domain, caller) are the following two arguments
	* ====== ENCODED ON REMOTE CHAIN ======
	* 3. Root timestamp is the last argument,
	* and will be appended before the call on destination chain.
	*/
	return abi.encodePacked(_data, abi.encode(localDomain, _caller));
	}

sanguine/packages/contracts-core/contracts/system/SystemRouter.sol

Lines 175 to 186 in 3d61027

	function _localSystemCall(
	uint8 _recipient,
	bytes memory _payload,
	uint256 _rootSubmittedAt
	) internal {
	address recipient = _getSystemAddress(_recipient);
	require(recipient != address(0), "System Contract not set");
	// this will call recipient and bubble the revert from the external call
	recipient.functionCall(abi.encodePacked(_payload, _rootSubmittedAt));
	/// @dev add root timestamp as the last argument
	/// uint256 type allows us to use encodePacked w/o casting
	}

Using these three parameters, a system contract can enforce any types of checks for external functions, e.g.

• Function can be only called by Origin
• Function can be only called from a local chain
• Function can be only called from Synapse chain
• Function can be only called if optimistic period of X hours has passed
• Etc (including any combination of the above)

sanguine/packages/contracts-core/contracts/system/SystemContract.sol

Lines 55 to 64 in 3d61027

	/**
	* @dev Modifier for functions that are supposed to be called only from
	* System Contracts on Synapse chain.
	* Note: has to be used alongside with `onlySystemRouter`
	* See `onlySystemRouter` for details about the functions protected by such modifiers.
	*/
	modifier onlySynapseChain(uint32 _originDomain) {
	require(_originDomain == SYNAPSE_DOMAIN, "!synapseDomain");
	_;
	}

TODO

• Finish tests for remote multicalls
• Expose additional multicall methods: turned into Implement wrappers for system multicall methods  #198
• Simplify system router tests: part of Make Foundry tests easier to read #57

Metadata:

• Closes Internal messaging #52

[codecov]

Codecov Report

Merging #182 (3d61027) into master (0cbebef) will increase coverage by 0.41843%.
The diff coverage is 93.22034%.

@@                 Coverage Diff                 @@
##              master        #182         +/-   ##
===================================================
+ Coverage   50.72043%   51.13886%   +0.41843%     
===================================================
  Files            190         191          +1     
  Lines           8606        8649         +43     
  Branches          82          87          +5     
===================================================
+ Hits            4365        4423         +58     
+ Misses          3818        3803         -15     
  Partials         423         423                 

Impacted Files	Coverage Δ
...contracts-core/contracts/context/DomainContext.sol	100.00000% <ø> (ø)
...ntracts-core/test/harnesses/DestinationHarness.sol	100.00000% <ø> (ø)
...es/contracts-core/test/harnesses/OriginHarness.sol	66.66667% <ø> (-8.33334%)	⬇️
...s/contracts-core/contracts/system/SystemRouter.sol	90.69767% <90.00000%> (+14.22708%)	⬆️
...contracts-core/contracts/system/SystemContract.sol	66.66667% <100.00000%> (+33.33333%)	⬆️
...acts-core/test/harnesses/SystemContractHarness.sol	100.00000% <100.00000%> (ø)
services/scribe/backfill/contract.go	76.92308% <0.00000%> (+1.28204%)	⬆️
ethergo/chain/block.go	70.16129% <0.00000%> (+1.61289%)	⬆️
ethergo/signer/signer/kmssigner/signing.go	42.39130% <0.00000%> (+3.26087%)	⬆️
... and 1 more

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[trajan0x]

Finished a first pass review. Going to finish up a few other things then go through this again

[trajan0x]

LGTM