Circle Gateway Contracts

These are the contracts that support the Circle Gateway product. See the contract docs or Circle's website for more information about the product and how to use it.

Install dependencies

• Run git submodule update --init --recursive to update/download all libraries.
• Ensure Yarn is installed and then run yarn install to install additional JS dependencies.

Install Foundry CLI

• Run curl -L https://foundry.paradigm.xyz | bash
• Follow the instructions of that command to source env file
• run foundryup --install v1.0.0

Deployment

How it works

The deployment steps are:

1. Deploy the UpgradablePlaceholder implementation
2. Deploy the actual implementation (e.g. GatewayMinter)
3. Deploy the ERC1967Proxy and setup the proxy:
   1. Deploy the ERC1967 Proxy, set the implementation to UpgradablePlaceholder and initialize the owner to Create2Factory address.
   2. In the same transcation, upgrade the implementation to actual implementation and initialize the implementation properly.

The reason of setting owner of UpgradablePlaceholder to Create2Factory address is that since the owner is part of the address computation, we want to use Create2Factory to avoid managing an extra EOA key.

Since the owner of UpgradablePlaceholder is Create2Factory and only the owner can perform upgradeToAndCall, we decided to use Create2Factory.deployAndMultiCall to upgrade to actual implementation in the proxy deployment call.

Prerequisites

Before deploying the contracts, ensure you have:

1. Create a .env file from .env.example and set up environment variables in .env file.

2. Run source .env to load the environment variables in your shell.

3. Verified you have sufficient funds in the deployer account for the target network

Deploying Contracts

Step 1: Start a local blockchain

Only needed for local deployment

Start a local RPC node at http://127.0.0.1:8485 by running anvil.

Step 2: Deploy Create2Factory Contract

Only needed for local deployment

Local Deployment

Run the following command to deploy a test instance of the Create2Factory contract:

forge create Create2Factory -r http://127.0.0.1:8545 --broadcast --private-key $DEPLOYER_PRIVATE_KEY --constructor-args $DEPLOYER_ADDRESS

• DEPLOYER_PRIVATE_KEY: Any key from anvil pre-funded addresses.
• DEPLOYER_ADDRESS: This address should match the $DEPLOYER_ADDRESS in .env

Add the deployed Create2Factory contract address to your .env file under the variable LOCAL_CREATE2_FACTORY_ADDRESS.

Local deployment

Follow the instructions in evm-cctp-contracts-private README to deploy Create2Factory. Update LOCAL_DEPLOYER_ADDRESS and LOCAL_CREATE2_FACTORY_ADDRESS in .env.

Step3: Generate Deployment Transactions for GatewayWallet and GatewayMinter.

Run the following command to generate deployment transactions for GatewayWallet and GatewayMinter:

ENV=$ENV forge script script/001_DeployGatewayWallet.sol --rpc-url $RPC_URL -vvvv --slow --force
ENV=$ENV forge script script/001_DeployGatewayMinter.sol --rpc-url $RPC_URL -vvvv --slow --force

• ENV: Use LOCAL for local deployment. Or choose from TESTNET_STAGING, TESTNET_PROD, and MAINNET_PROD.
• RPC_URL: The rpc url for the targeted blockchain. use http://127.0.0.1:8485 for local deployment.

The generated transaction data will be available in the broadcast/ directory and can be used for signing.

Deployed contract validation

Fill in the Deployed Contract Validation section in .env and run:

forge script script/003_DeployedContractValidation.s.sol --rpc-url $RPC_URL -vvvv --slow --force

This command validates deployed contract bytecode matches expected bytecode and contract state matches expected values.

How to Update Deployment Scripts

Update Compiled Contract Artifacts

Run the following command to generate new artifacts if openzeppelin-contracts submodule is updated. Current commit hash is acd4ff7.

forge build lib/openzeppelin-contracts/contracts/proxy/ERC1967/ERC1967Proxy.sol --force
cp out/ERC1967Proxy.sol/ERC1967Proxy.json script/compiled-contract-artifacts/ERC1967Proxy.json

Run the following command to generate new artifacts for Gateway smart contracts.

forge build src/UpgradeablePlaceholder.sol --force
cp out/UpgradeablePlaceholder.sol/UpgradeablePlaceholder.json script/compiled-contract-artifacts/UpgradeablePlaceholder.json

forge build src/GatewayMinter.sol --force
cp out/GatewayMinter.sol/GatewayMinter.json script/compiled-contract-artifacts/GatewayMinter.json

forge build src/GatewayWallet.sol --force
cp out/GatewayWallet.sol/GatewayWallet.json script/compiled-contract-artifacts/GatewayWallet.json

Find New Salts

Find salts that creates gas-efficient proxy addresses via:

cast create2 --starts-with $ADDRESS_PREFIX --deployer $DEPLOYER> --init-code-hash $INIT_CODE_HASH

• ADDRESS_PREFIX is the prefix of the address we want to find. Usually set to 00000000 for a gas-efficient address.
• DEPLOYER is the address of Create2Factory.
• INIT_CODE_HASH is keccak256 hash of initcode + abi-encoded constuctor argument.

We have chosen the following prefixes for our top-level contracts:

Environment	Network Type	Wallet Prefix	Minter Prefix	Notes
Production	Mainnet	0x7777777	0x2222222
Production	Testnet	0x0077777	0x0022222	Add zero byte to mainnet addresses
Staging	Testnet	0x5577777	0x5522222	5 = "S" for Staging

To find and verify salts for the Wallet and Minter contracts, correctly set the ENV and RPC_URL environment variables (and possible LOCAL_CREATE2_FACTORY_ADDRESS depending on your environment). Use any values for all of the other variables, as they do not matter here.

Simulate the deployments by running the below commands and note down the values initCodeHash from the logs of each command

1. ENV=$ENV forge script script/001_DeployGatewayWallet.sol --rpc-url $RPC_URL -vv
2. ENV=$ENV forge script script/002_DeployGatewayMinter.sol --rpc-url $RPC_URL -vv

Then, run the following command:

# Use the same value specified in the 000_Constants.sol or `LOCAL_CREATE2_FACTORY_ADDRESS` (depending on your environment)  
export SALT_MINE_CREATE2_FACTORY_ADDRESS=

# Use values of previous step's logs
export WALLET_PROXY_INIT_CODE_HASH=
export MINTER_PROXY_INIT_CODE_HASH=

# Make sure ENV has been set before calling this command (see .env file)
yarn mine-salts

Update the salts in 000_Constants.sol and re-simulate the deployments to verify that the proxy addresses have been updated to the expected prefixes.

Test

Unit Tests and Fork Tests (Foundry)

To run tests using Foundry, run yarn test. This will run all tests using the default Anvil localnet.

To run tests against each supported network (by forking from each network's RPC endpoint), run yarn test:all. If failures related to remote state from an old block are encountered, either point to archive nodes or run ./scripts/update_block_numbers.sh to pin the latest block for each network and try again.

To run tests and output a gas report for the top-level contracts, run yarn test:gas.

Mock FiatToken port

To simplify local development and testing we have a local port of the FiatToken contracts from the https://github.com/circlefin/stablecoin-evm repo. The port is based on commit 0642db6. When there are essential changes to the FiatToken contracts (e.g., new version release), we'll need to:

1. Go through the diff between the above commit and the latest version, applying the latest changes into test/mock_fiattoken
2. Update dependency imports and relative imports
3. Bump solidity version and fix resulting compiler errors
4. Update test/util/DeployMockFiatToken.sol if necessary

Linting and Formatting

Run yarn lint to lint all .sol files in the src and test directories, and yarn lint:fix to automatically fix any fixable linting errors.

Run yarn format to check the formatting of all .sol files in the src and test directories, and yarn format:fix to automatically format them.

Coverage

Run yarn coverage to generate a coverage report for the tests. This depends on the lcov and genhtml commands, which may be installed on macOS with brew install lcov. The coverage report will be generated in the coverage directory.

Development

Contract Sizes

To check the bytecode size of all top-level contracts against the EIP-170 contract size limit, run yarn sizes.

Important Considerations: Memory Initialization with TypedMemView

This project relies heavily on the TypedMemView library (lib/memview-sol/) for efficient memory manipulation.

Warning: As documented in the TypedMemView library itself, it utilizes unallocated memory operations and does not guarantee cleanup of unallocated memory regions after its internal functions execute.

Implication: This means that memory subsequently allocated by contracts in this project (e.g., declaring new memory variables like arrays or structs after TypedMemView operations have occurred within the same transaction execution path) might not be zero-initialized. It could contain residual data from previous operations.

Required Precaution: Developers working on this codebase must not assume that newly allocated memory variables or structures are automatically zero-initialized. If the logic relies on a memory variable starting at zero (or false, address(0), etc.), it must be explicitly initialized after allocation.

Continuous Integration using Github Actions

We use Github actions to run the linter and all the tests. The workflow configuration can be found in .github/workflows/pipeline.yml. While not a complete replacement, all CI steps may be run locally with yarn ci.

Manual Triggering of the Olympix CI Workflow

You can manually trigger the Olympix.ai Code Scanning workflow using the workflow_dispatch feature of GitHub Actions.

1. Click on the Actions tab.
2. In the left sidebar, select Olympix Scan.
3. Select the branch & click on the Run workflow button.