轻松上手 Chainlink CCIP：Sepolia → BSC Testnet 跨链消息全流程

CCIP 简介（超简）

• CCIP（Cross-Chain Interoperability Protocol）：Chainlink 推出的跨链消息与资产传输协议。
• 本示例：在 Ethereum Sepolia 上发送一条文本消息，经 CCIP 路由传到 BSC Testnet 并被目标链合约接收与解码。

架构与流程

• 源链：Sepolia；合约：Sender
• 目标链：BSC Testnet；合约：Receiver
• 流程：Sender.sendMessage(...) → CCIP 路由跨链 → Receiver._ccipReceive(...) 解码与记录

快速上手步骤（概览）

• 在 BSC Testnet 部署 Receiver（构造写死 Router 地址）
• 在 Sepolia 部署 Sender（构造写死 Router 与 LINK 地址）
• 向 Sender 合约转入足量 LINK → 调 sendMessage(chainSelector, receiver, "hello")
• 在 BSC Testnet 监听 MessageReceived 或读 getLastReceivedMessageDetails()

源码：Receiver（BSC Testnet 接收）

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.7;

import {Client} from "@chainlink/contracts-ccip@1.6.0/contracts/libraries/Client.sol";
import {CCIPReceiver} from "@chainlink/contracts-ccip@1.6.0/contracts/applications/CCIPReceiver.sol";

/**
 * THIS IS AN EXAMPLE CONTRACT THAT USES HARDCODED VALUES FOR CLARITY.
 * THIS IS AN EXAMPLE CONTRACT THAT USES UN-AUDITED CODE.
 * DO NOT USE THIS CODE IN PRODUCTION.
 */
/**
bsc测试网接收消息
1. 部署合约
**/

/// @title - A simple contract for receiving string data across chains.
contract Receiver is CCIPReceiver {
    // Event emitted when a message is received from another chain.
    event MessageReceived(
        bytes32 indexed messageId, // The unique ID of the message.
        uint64 indexed sourceChainSelector, // The chain selector of the source chain.
        address sender, // The address of the sender from the source chain.
        string text // The text that was received.
    );

    bytes32 private s_lastReceivedMessageId; // Store the last received messageId.
    string private s_lastReceivedText; // Store the last received text.

    /// @notice Constructor initializes the contract with the router address.
    /// 写死bsc testnet的router:0xE1053aE1857476f36A3C62580FF9b016E8EE8F6f
    constructor() CCIPReceiver(0xE1053aE1857476f36A3C62580FF9b016E8EE8F6f) {}

    /// handle a received message
    function _ccipReceive(
        Client.Any2EVMMessage memory any2EvmMessage
    ) internal override {
        s_lastReceivedMessageId = any2EvmMessage.messageId; // fetch the messageId
        s_lastReceivedText = abi.decode(any2EvmMessage.data, (string)); // abi-decoding of the sent text

        emit MessageReceived(
            any2EvmMessage.messageId,
            any2EvmMessage.sourceChainSelector, // fetch the source chain identifier (aka selector)
            abi.decode(any2EvmMessage.sender, (address)), // abi-decoding of the sender address,
            abi.decode(any2EvmMessage.data, (string))
        );
    }

    /// @notice Fetches the details of the last received message.
    /// @return messageId The ID of the last received message.
    /// @return text The last received text.
    function getLastReceivedMessageDetails()
        external
        view
        returns (bytes32 messageId, string memory text)
    {
        return (s_lastReceivedMessageId, s_lastReceivedText);
    }
}

源码：Sender（Sepolia 发送）

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.7;

import {IRouterClient} from "@chainlink/contracts-ccip@1.6.0/contracts/interfaces/IRouterClient.sol";
import {OwnerIsCreator} from "@chainlink/contracts@1.4.0/src/v0.8/shared/access/OwnerIsCreator.sol";
import {Client} from "@chainlink/contracts-ccip@1.6.0/contracts/libraries/Client.sol";
import {LinkTokenInterface} from "@chainlink/contracts@1.4.0/src/v0.8/shared/interfaces/LinkTokenInterface.sol";

/**
 * THIS IS AN EXAMPLE CONTRACT THAT USES HARDCODED VALUES FOR CLARITY.
 * THIS IS AN EXAMPLE CONTRACT THAT USES UN-AUDITED CODE.
 * DO NOT USE THIS CODE IN PRODUCTION.
 */

/**
从sepolia发送消息给bsc测试网
1. 部署合约
2. 给合约转账70link
**/

/// @title - A simple contract for sending string data across chains.
contract Sender is OwnerIsCreator {
    // Custom errors to provide more descriptive revert messages.
    error NotEnoughBalance(uint256 currentBalance, uint256 calculatedFees); // Used to make sure contract has enough balance.

    // Event emitted when a message is sent to another chain.
    event MessageSent(
        bytes32 indexed messageId, // The unique ID of the CCIP message.
        uint64 indexed destinationChainSelector, // The chain selector of the destination chain.
        address receiver, // The address of the receiver on the destination chain.
        string text, // The text being sent.
        address feeToken, // the token address used to pay CCIP fees.
        uint256 fees // The fees paid for sending the CCIP message.
    );

    IRouterClient private s_router;

    LinkTokenInterface private s_linkToken;

    /// @notice Constructor initializes the contract with the router address.
    constructor() {
        // 写死sepolia的router和link地址
        address _router =0x0BF3dE8c5D3e8A2B34D2BEeB17ABfCeBaf363A59;
        address _link =  0x779877A7B0D9E8603169DdbD7836e478b4624789;
        s_router = IRouterClient(_router);
        s_linkToken = LinkTokenInterface(_link);
    }

    /// @notice Sends data to receiver on the destination chain.
    /// @dev Assumes your contract has sufficient LINK.
    /// @param destinationChainSelector The identifier (aka selector) for the destination blockchain.
    /// @param receiver The address of the recipient on the destination blockchain.
    /// @param text The string text to be sent.
    /// @return messageId The ID of the message that was sent.
    function sendMessage(
        uint64 destinationChainSelector,
        address receiver,
        string calldata text
    ) external onlyOwner returns (bytes32 messageId) {
        // Create an EVM2AnyMessage struct in memory with necessary information for sending a cross-chain message
        Client.EVM2AnyMessage memory evm2AnyMessage = Client.EVM2AnyMessage({
            receiver: abi.encode(receiver), // ABI-encoded receiver address
            data: abi.encode(text), // ABI-encoded string
            tokenAmounts: new Client.EVMTokenAmount[](0), // Empty array indicating no tokens are being sent
            extraArgs: Client._argsToBytes(
                // Additional arguments, setting gas limit and allowing out-of-order execution.
                // Best Practice: For simplicity, the values are hardcoded. It is advisable to use a more dynamic approach
                // where you set the extra arguments off-chain. This allows adaptation depending on the lanes, messages,
                // and ensures compatibility with future CCIP upgrades. Read more about it here: https://docs.chain.link/ccip/concepts/best-practices/evm#using-extraargs
                Client.GenericExtraArgsV2({
                    gasLimit: 200_000, // Gas limit for the callback on the destination chain
                    allowOutOfOrderExecution: true // Allows the message to be executed out of order relative to other messages from the same sender
                })
            ),
            // Set the feeToken  address, indicating LINK will be used for fees
            feeToken: address(s_linkToken)
        });

        // Get the fee required to send the message
        uint256 fees = s_router.getFee(
            destinationChainSelector,
            evm2AnyMessage
        );

        if (fees > s_linkToken.balanceOf(address(this)))
            revert NotEnoughBalance(s_linkToken.balanceOf(address(this)), fees);

        // approve the Router to transfer LINK tokens on contract's behalf. It will spend the fees in LINK
        s_linkToken.approve(address(s_router), fees);

        // Send the message through the router and store the returned message ID
        messageId = s_router.ccipSend(destinationChainSelector, evm2AnyMessage);

        // Emit an event with message details
        emit MessageSent(
            messageId,
            destinationChainSelector,
            receiver,
            text,
            address(s_linkToken),
            fees
        );

        // Return the message ID
        return messageId;
    }
}

实战提示（简版）

• 确认两链的 CCIP Router 地址与 Chain Selector 为官方最新值。
• feeToken 使用 LINK 时，需要先将 LINK 转入 Sender 合约，并 approve 费用。
• gasLimit 需与接收逻辑复杂度匹配；开启 allowOutOfOrderExecution 时注意幂等与去重（用 messageId）。

如果需要，我可以补充一份一键部署与调用的脚本（Hardhat/Foundry），并附上常用测试网的 chain selector 与 Router 地址清单，帮助你从部署到演示全流程跑通。