route.ts
For the full content of this gist, refer to https://gist.github.com/CodingAbdullah/18319e99d88b9781f7c27ee588592300
McMaster. Software Engineer with a keen interest in blockchain and web3.
import { ethers } from "ethers";
import { NextRequest, NextResponse } from "next/server";
const CONTRACT_ADDRESS = process.env.NEXT_PUBLIC_CONTRACT_ADDRESS!;
const REQUIRED_AMOUNT = BigInt(50000); // 0.05 USDC (6 decimals)
const RPC_URL = process.env.BASE_SEPOLIA_RPC || "https://sepolia.base.org";
// Matches the PaymentReceived event in X402_Protocol_USDC.sol
const PAYMENT_EVENT_ABI = [
"event PaymentReceived(address indexed user, uint256 amount)",
];
export async function GET(req: NextRequest) {
const txHash = req.headers.get("x-payment-tx-hash");
// No payment header → 402 with requirements
if (!txHash) {
return NextResponse.json(
{
error: "Payment Required",
paymentDetails: {
protocol: "x402",
network: "base-sepolia",
chainId: 84532,
token: "USDC",
contractAddress: CONTRACT_ADDRESS,
amount: "0.05",
amountRaw: "50000",
decimals: 6,
steps: ["approve USDC for contract", "call pay()"],
},
},
{ status: 402 }
);
}
try {
const provider = new ethers.JsonRpcProvider(RPC_URL);
const receipt = await provider.getTransactionReceipt(txHash);
if (!receipt) {
return NextResponse.json(
{ error: "Transaction not found on Base Sepolia" },
{ status: 402 }
);
}
// Decode PaymentReceived events emitted by the X402Protocol contract
const iface = new ethers.Interface(PAYMENT_EVENT_ABI);
let paymentVerified = false;
for (const log of receipt.logs) {
if (log.address.toLowerCase() !== CONTRACT_ADDRESS.toLowerCase()) continue;
try {
const parsed = iface.parseLog({
topics: log.topics as string[],
data: log.data,
});
if (
parsed?.name === "PaymentReceived" &&
BigInt(parsed.args.amount) >= REQUIRED_AMOUNT
) {
paymentVerified = true;
break;
}
} catch {
// log is not a PaymentReceived event — skip
}
}
if (!paymentVerified) {
return NextResponse.json(
{ error: "Payment verification failed — PaymentReceived event not found or amount insufficient" },
{ status: 402 }
);
}
// Payment confirmed → return the protected resource
return NextResponse.json({ message: "Hello World" }, { status: 200 });
}
catch {
return NextResponse.json(
{ error: "Failed to verify transaction on-chain" },
{ status: 402 }
);
}
}