CCIP Best Practices
Before you deploy your cross-chain dApps to mainnet, make sure that your dApps follow the best practices in this document. You are responsible for thoroughly reviewing your code and applying best practices to ensure that your cross-chain dApps are secure and reliable. If you have a unique use case for CCIP that might involve additional cross-chain risk, contact the Chainlink Labs Team before deploying your application to mainnet.
Verify destination chain
Before calling the router's ccipSend
function, ensure that your code allows users to send CCIP messages to trusted destination chains.
Verify source chain
When implementing the ccipReceive
method in a contract residing on the destination chain, ensure to verify the source chain of the incoming CCIP message. This verification ensures that CCIP messages can only be received from trusted source chains.
Verify sender
When implementing the ccipReceive
method in a contract residing on the destination chain, it's important to validate the sender of the incoming CCIP message. This check ensures that CCIP messages are received only from trusted sender addresses.
Note: Depending on your use case, this verification might not always be necessary.
Verify router addresses
When you implement the ccipReceive
method in the contract residing on the destination chain, validate that the msg.sender
is the correct router address. This verification ensures that only the router contract can call the ccipReceive
function on the receiver contract and is for developers that want to restrict which accounts are allowed to call ccipReceive
.
Setting gasLimit
The gasLimit
specifies the maximum amount of gas CCIP can consume to execute ccipReceive()
on the contract located on the destination blockchain. It is the main factor in determining the fee to send a message. Unspent gas is not refunded.
To transfer tokens directly to an EOA as a receiver on the destination blockchain, the gasLimit
should be set to 0
since there is no ccipReceive()
implementation to call.
To estimate the accurate gas limit for your destination contract, consider the following options:
- Leveraging Ethereum client RPC by applying
eth_estimateGas
onreceiver.ccipReceive()
. You can find more information on the Ethereum API Documentation and Alchemy documentation. - Conducting Foundry gas tests.
- Using Hardhat plugin for gas tests.
- Using a blockchain explorer to look up the gas consumption of a particular internal transaction.
Using extraArgs
The purpose of extraArgs
is to allow compatibility with future CCIP upgrades. To get this benefit, make sure that extraArgs
is mutable in production deployments. This allows you to build it offchain and pass it in a call to a function or store it in a variable that you can update on-demand.
If extraArgs
are left empty, a default of 200000 gasLimit
will be set.
Decoupling CCIP Message Reception and Business Logic
As a best practice, separate the reception of CCIP messages from the core business logic of the contract. Implement 'escape hatches' or fallback mechanisms to gracefully manage situations where the business logic encounters issues. To explore this concept further, refer to the Defensive Example guide.
Evaluate the security and reliability of the networks that you use
Although CCIP has been thoroughly reviewed and audited, inherent risks might still exist based on your use case, the blockchain networks where you deploy your contracts, and the network conditions on those blockchains.
Review and audit your code
Before securing value with contracts that implement CCIP interfaces and routers, ensure that your code is secure and reliable. If you have a unique use case for CCIP that might involve additional cross-chain risk, contact the Chainlink Labs Team before deploying your application to mainnet.
Soak test your dApps
Be aware of the Service Limits and Rate Limits for Supported Networks. Before you provide access to end users or secure value, soak test your cross-chain dApps. Ensure that your dApps can operate within these limits and operate correctly during usage spikes or unfavorable network conditions.
Monitor your dApps
When you build applications that depend on CCIP, include monitoring and safeguards to protect against the negative impact of extreme market events, possible malicious activity on your dApp, potential delays, and outages.
Create your own monitoring alerts based on deviations from normal activity. This will notify you when potential issues occur so you can respond to them.