# Chainlink CCIP Smart Contracts

> [!IMPORTANT] 
> Since v1.6.0 of the CCIP contracts, the contracts have been moved to a new repository:
> [chainlink-ccip](https://github.com/smartcontractkit/chainlink-ccip).
> The EVM contracts exist in the `chains/evm` directory of the repository.

## Installation

Chainlink-ccip relies on chainlink-evm, below are the instructions to install both.
To find the correct version of chainlink-evm to use for any given version of chainlink-ccip, 
please refer to the `package.json` file in `/chains/evm`.
It contains an NPM dependency on `@chainlink/contracts` with the correct version for the given version of chainlink-ccip.

NOTE: while other versions of chainlink-evm may work, we only test against the version specified in the `package.json` file.
Audits are also only done against the version specified in the `package.json` file. 
No guarantees are made for other versions.

#### Foundry (git)

> [!WARNING]
> When installing via git, the ref defaults to master when no tag is given.

When installing through git, it is recommended to use a specific version tag to avoid breaking changes.
The corresponding git tag will be `contracts-ccip-v<version>` for chainlink-ccip, 
and `contracts-v<version>` for chainlink-evm.

```sh
forge install smartcontractkit/chainlink-evm@contracts-v1.5.0
forge install smartcontractkit/chainlink-ccip@contracts-ccip-v2.0.0
forge install foundry-rs/forge-std@v1.16.1
```

CCIP contracts also depend on OpenZeppelin and Chainlink ACE packages that are distributed via npm.
Install the versions listed in `package.json` for the CCIP release you are using:

```sh
pnpm add @chainlink/ace@1.0.0
pnpm add @openzeppelin/contracts-4.8.3@npm:@openzeppelin/contracts@4.8.3
pnpm add @openzeppelin/contracts-5.3.0@npm:@openzeppelin/contracts@5.3.0
```

Add the following remappings to `remappings.txt`:

```
forge-std/=lib/forge-std/src/
@chainlink/contracts/=lib/chainlink-evm/contracts/
@chainlink/contracts-ccip/contracts/=lib/chainlink-ccip/chains/evm/contracts/
@chainlink/policy-management/=node_modules/@chainlink/ace/packages/policy-management/src/
@openzeppelin/contracts@4.8.3=node_modules/@openzeppelin/contracts-4.8.3
@openzeppelin/contracts@5.3.0=node_modules/@openzeppelin/contracts-5.3.0
```

#### (P)NPM

```sh
# pnpm
pnpm add @chainlink/contracts@1.5.0
pnpm add @chainlink/contracts-ccip@2.0.0
pnpm add @chainlink/ace@1.0.0
pnpm add @openzeppelin/contracts-4.8.3@npm:@openzeppelin/contracts@4.8.3
pnpm add @openzeppelin/contracts-5.3.0@npm:@openzeppelin/contracts@5.3.0
```
```sh
# npm
npm install @chainlink/contracts@1.5.0 --save
npm install @chainlink/contracts-ccip@2.0.0 --save
npm install @chainlink/ace@1.0.0 --save
npm install @openzeppelin/contracts-4.8.3@npm:@openzeppelin/contracts@4.8.3 --save
npm install @openzeppelin/contracts-5.3.0@npm:@openzeppelin/contracts@5.3.0 --save
```

Add the following remappings to `remappings.txt`:

```
@chainlink/contracts/=node_modules/@chainlink/contracts/
@chainlink/contracts-ccip/contracts/=node_modules/@chainlink/contracts-ccip/contracts/
@chainlink/policy-management/=node_modules/@chainlink/ace/packages/policy-management/src/
@openzeppelin/contracts@4.8.3=node_modules/@openzeppelin/contracts-4.8.3
@openzeppelin/contracts@5.3.0=node_modules/@openzeppelin/contracts-5.3.0
```

### Directory Structure

```sh
@chainlink/contracts-ccip
├── contracts # Solidity contracts
├── scripts # Compilation script
└── abi # ABI json output
```

### Usage

> [!WARNING]
> Contracts in `dev/` directories or with a typeAndVersion ending in `-dev` are under active development
> and are likely unaudited.
> Please refrain from using these in production applications.


The contracts can be imported via `@chainlink/contracts-ccip/contracts`:

```solidity
import {CCIPReceiver} from '@chainlink/contracts-ccip/contracts/applications/CCIPReceiver.sol';
```

#### Getting started with CCIP

To get started with CCIP, please refer to the [CCIP documentation](https://docs.chain.link/ccip).

The MockRouter contract is a good starting point when developing dapps that use CCIP.
It is a simplified same-chain entry and exit point for CCIP messages.
It lives in `contracts/test/mocks/MockRouter.sol`.


### Remapping

This repository uses [Solidity remappings](https://docs.soliditylang.org/en/v0.8.20/using-the-compiler.html#compiler-remapping) to resolve imports.

The `remappings.txt` file in this directory contains the remappings used when developing CCIP itself via npm.
When consuming CCIP in another project, use the remappings from the Installation section above, which additionally include the `@chainlink/contracts-ccip/contracts/` prefix.

CCIP contracts import versioned OpenZeppelin packages using aliases such as `@openzeppelin/contracts@5.3.0`.
The remappings above map those aliases to the corresponding npm package directories (for example, `@openzeppelin/contracts-5.3.0`).
This allows you to use a wide range of versions of Openzeppelin in your project without conflicts.

### Changesets

We use [changesets](https://github.com/changesets/changesets) to manage versioning the contracts.

Every PR that modifies any configuration or code, should most likely accompanied by a changeset file.

To install `changesets`:

1. Install `pnpm` if it is not already installed - [docs](https://pnpm.io/installation).
2. Run `pnpm install`.

Either after or before you create a commit, run the `pnpm changeset` command in the `chains/evm` directory to create an accompanying changeset entry which will reflect on the CHANGELOG for the next release.

The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/) and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).

## License

The CCIP contracts are licensed under the [BUSL-1.1](./contracts/LICENSE.md) license.
See [v2.0-CCIP-License-grants](./contracts/v2.0-CCIP-License-grants.md) for additional use grants.