Airnode attemps to fail the request when the sponsor wallet is invalid

[bbenligiray]

Run yarn && yarn main on https://github.com/bbenligiray/fulfillment-analysis and you will see a bunch of reverted transactions that attempt to call fail() with the errorMessage Sponsor wallet is invalid.... These fail() calls of course revert because the sponsor wallet is invalid. This is a DoS vector for certain advanced user patterns for RRP (where you let the end-user specify the sponsor wallet).

When the sponsor wallet for a request is invalid, Airnode should just log it and ignore it on-chain.

[dcroote]

I was able to reproduce this by using the wrong sponsor wallet address:
https://sepolia.etherscan.io/tx/0x54478cdca3f585fcb07ed85180ed87eee8401dc2b3008be64f3bf570a499ef2d

The relevant code for the error is below, with RequestErrorMessage.SponsorWalletInvalid being the error message Sponsor wallet is invalid:

airnode/packages/airnode-node/src/api/index.ts

Lines 104 to 118 in a14f3b0

	export function verifySponsorWallet(payload: RegularApiCallPayload): LogsData<ApiCallErrorResponse> | null {
	const { config, aggregatedApiCall } = payload;
	const { sponsorAddress, sponsorWalletAddress, id } = aggregatedApiCall;
	const derivedSponsorWallet = deriveSponsorWalletFromMnemonic(
	config.nodeSettings.airnodeWalletMnemonic,
	sponsorAddress
	);
	if (derivedSponsorWallet.address === sponsorWalletAddress) return null;
	// TODO: Abstract this to a logging utils file
	const message = `${RequestErrorMessage.SponsorWalletInvalid}, Request ID:${id}`;
	const log = logger.pend('ERROR', message);
	return [[log], { success: false, errorMessage: message }];
	}

When the sponsor wallet for a request is invalid, Airnode should just log it and ignore it on-chain.

It turns out we already do this for withdrawal requests:

airnode/packages/airnode-node/src/evm/verification/request-verification.ts

Lines 8 to 28 in a14f3b0

	export function verifySponsorWallets<T>(
	unverifiedRequests: Request<T>[],
	masterHDNode: ethers.utils.HDNode
	): LogsData<Request<T>[]> {
	const { logs, requests } = unverifiedRequests.reduce(
	(acc, request) => {
	const expectedSponsorWalletAddress = wallet.deriveSponsorWallet(masterHDNode, request.sponsorAddress).address;
	if (request.sponsorWalletAddress !== expectedSponsorWalletAddress) {
	const message = `Invalid sponsor wallet:${request.sponsorWalletAddress} for Request:${request.id}. Expected:${expectedSponsorWalletAddress}`;
	const log = logger.pend('ERROR', message);
	return { ...acc, logs: [...acc.logs, log] };
	}
	const message = `Request ID:${request.id} is linked to a valid sponsor wallet:${request.sponsorWalletAddress}`;
	const log = logger.pend('DEBUG', message);
	return { ...acc, logs: [...acc.logs, log], requests: [...acc.requests, request] };
	},
	{ logs: [], requests: [] } as UpdatedRequests<T>
	);
	return [logs, requests];
	}

[aTeoke]

Just to add, we are only patching the current version 0.11.0 upon agreement on Airnode weekly call(week ago).

[dcroote]

@aTeoke - to test this you can follow the airnode-example coingecko flow, but before making the request, change the sponsor wallet to something random (invalid) in the coingecko/request-utils.ts file:

airnode/packages/airnode-examples/integrations/coingecko/request-utils.ts

Lines 17 to 21 in f49228a

	const sponsorWalletAddress = await deriveSponsorWalletAddress(
	deriveAirnodeXpub(airnodeWallet.mnemonic.phrase),
	airnodeWallet.address,
	sponsor.address
	);

Before this PR, the result would be a failed tx like I linked to in my comment above. Now, Airnode ignores the request because the sponsor wallet is invalid and does not make the API call or submit a tx.

[aTeoke]

Tested it, Derek guided me through it and we can consider this one done and working ok