Onchain Data Verification
Verify reports onchain
To verify data onchain on EVM chains, Streams Direct requires several Solidity interfaces.
The primary onchain interaction occurs between the IVerifierProxy interface and your protocol's client contract. Find the Verifier proxy address for each stream on the Stream Addresses page.
Interfaces
- IVerifierProxy
- IFeeManager
In the current code example for verifying reports onchain using Streams Direct, these interfaces are specified in the example itself. Imports for these interfaces will be available in the future.
Contract example to verify report data onchain
This contract example allows you to verify reports and pay the verification fee in LINK tokens. Your contract must have sufficient LINK tokens to pay for the verification fee. Learn how to fund your contract with LINK tokens.
// SPDX-License-Identifier: MIT
pragma solidity 0.8.19;
import {Common} from "@chainlink/contracts/src/v0.8/llo-feeds/libraries/Common.sol";
import {IRewardManager} from "@chainlink/contracts/src/v0.8/llo-feeds/interfaces/IRewardManager.sol";
import {IVerifierFeeManager} from "@chainlink/contracts/src/v0.8/llo-feeds/interfaces/IVerifierFeeManager.sol";
import {IERC20} from "@chainlink/contracts/src/v0.8/vendor/openzeppelin-solidity/v4.8.3/contracts/token/ERC20/IERC20.sol";
import {SafeERC20} from "@chainlink/contracts/src/v0.8/vendor/openzeppelin-solidity/v4.8.3/contracts/token/ERC20/utils/SafeERC20.sol";
using SafeERC20 for IERC20;
/**
* THIS IS AN EXAMPLE CONTRACT THAT USES UN-AUDITED CODE FOR DEMONSTRATION PURPOSES.
* DO NOT USE THIS CODE IN PRODUCTION.
*/
// Custom interfaces for IVerifierProxy and IFeeManager
interface IVerifierProxy {
/**
* @notice Verifies that the data encoded has been signed correctly by routing to the correct verifier, and bills the user if applicable.
* @param payload The encoded data to be verified, including the signed report.
* @param parameterPayload Fee metadata for billing. In the current implementation, this consists of the abi-encoded address of the ERC-20 token used for fees.
* @return verifierResponse The encoded report from the verifier.
*/
function verify(
bytes calldata payload,
bytes calldata parameterPayload
) external payable returns (bytes memory verifierResponse);
/**
* @notice Verifies multiple reports in bulk, ensuring that each is signed correctly, routes them to the appropriate verifier, and handles billing for the verification process.
* @param payloads An array of encoded data to be verified, where each entry includes the signed report.
* @param parameterPayload Fee metadata for billing. In the current implementation, this consists of the abi-encoded address of the ERC-20 token used for fees.
* @return verifiedReports An array of encoded reports returned from the verifier.
*/
function verifyBulk(
bytes[] calldata payloads,
bytes calldata parameterPayload
) external payable returns (bytes[] memory verifiedReports);
function s_feeManager() external view returns (IVerifierFeeManager);
}
interface IFeeManager {
/**
* @notice Calculates the fee and reward associated with verifying a report, including discounts for subscribers.
* This function assesses the fee and reward for report verification, applying a discount for recognized subscriber addresses.
* @param subscriber The address attempting to verify the report. A discount is applied if this address is recognized as a subscriber.
* @param unverifiedReport The report data awaiting verification. The content of this report is used to determine the base fee and reward, before considering subscriber discounts.
* @param quoteAddress The payment token address used for quoting fees and rewards.
* @return fee The fee assessed for verifying the report, with subscriber discounts applied where applicable.
* @return reward The reward allocated to the caller for successfully verifying the report.
* @return totalDiscount The total discount amount deducted from the fee for subscribers.
*/
function getFeeAndReward(
address subscriber,
bytes memory unverifiedReport,
address quoteAddress
) external returns (Common.Asset memory, Common.Asset memory, uint256);
function i_linkAddress() external view returns (address);
function i_nativeAddress() external view returns (address);
function i_rewardManager() external view returns (address);
}
/**
* @dev This contract implements functionality to verify Data Streams reports from
* the Streams Direct API or WebSocket connection, with payment in LINK tokens.
*/
contract ClientReportsVerifier {
error NothingToWithdraw(); // Thrown when a withdrawal attempt is made but the contract holds no tokens of the specified type.
error NotOwner(address caller); // Thrown when a caller tries to execute a function that is restricted to the contract's owner.
error InvalidReportVersion(uint16 version); // Thrown when an unsupported report version is provided to verifyReport.
/**
* @dev Represents a data report from a Data Streams stream for v3 schema (crypto streams).
* The `price`, `bid`, and `ask` values are carried to either 8 or 18 decimal places, depending on the stream.
* For more information, see https://docs.chain.link/data-streams/crypto-streams and https://docs.chain.link/data-streams/reference/report-schema
*/
struct ReportV3 {
bytes32 feedId; // The stream ID the report has data for.
uint32 validFromTimestamp; // Earliest timestamp for which price is applicable.
uint32 observationsTimestamp; // Latest timestamp for which price is applicable.
uint192 nativeFee; // Base cost to validate a transaction using the report, denominated in the chain’s native token (e.g., WETH/ETH).
uint192 linkFee; // Base cost to validate a transaction using the report, denominated in LINK.
uint32 expiresAt; // Latest timestamp where the report can be verified onchain.
int192 price; // DON consensus median price (8 or 18 decimals).
int192 bid; // Simulated price impact of a buy order up to the X% depth of liquidity utilisation (8 or 18 decimals).
int192 ask; // Simulated price impact of a sell order up to the X% depth of liquidity utilisation (8 or 18 decimals).
}
/**
* @dev Represents a data report from a Data Streams stream for v4 schema (RWA stream).
* The `price` value is carried to either 8 or 18 decimal places, depending on the stream.
* The `marketStatus` indicates whether the market is currently open. Possible values: `0` (`Unknown`), `1` (`Closed`), `2` (`Open`).
* For more information, see https://docs.chain.link/data-streams/rwa-streams and https://docs.chain.link/data-streams/reference/report-schema-v4
*/
struct ReportV4 {
bytes32 feedId; // The stream ID the report has data for.
uint32 validFromTimestamp; // Earliest timestamp for which price is applicable.
uint32 observationsTimestamp; // Latest timestamp for which price is applicable.
uint192 nativeFee; // Base cost to validate a transaction using the report, denominated in the chain’s native token (e.g., WETH/ETH).
uint192 linkFee; // Base cost to validate a transaction using the report, denominated in LINK.
uint32 expiresAt; // Latest timestamp where the report can be verified onchain.
int192 price; // DON consensus median benchmark price (8 or 18 decimals).
uint32 marketStatus; // The DON's consensus on whether the market is currently open.
}
IVerifierProxy public s_verifierProxy; // The VerifierProxy contract used for report verification.
address private s_owner; // The owner of the contract.
int192 public lastDecodedPrice; // Stores the last decoded price from a verified report.
event DecodedPrice(int192 price); // Event emitted when a report is successfully verified and decoded.
/**
* @param _verifierProxy The address of the VerifierProxy contract.
* You can find these addresses on https://docs.chain.link/data-streams/crypto-streams.
*/
constructor(address _verifierProxy) {
s_owner = msg.sender;
s_verifierProxy = IVerifierProxy(_verifierProxy);
}
/// @notice Checks if the caller is the owner of the contract.
modifier onlyOwner() {
if (msg.sender != s_owner) revert NotOwner(msg.sender);
_;
}
/**
* @notice Verifies an unverified data report and processes its contents, supporting both v3 and v4 report schemas.
* @dev Performs the following steps:
* - Decodes the unverified report to extract the report data.
* - Extracts the report version by reading the first two bytes of the report data.
* - The first two bytes correspond to the schema version encoded in the stream ID.
* - Schema version `0x0003` corresponds to report version 3 (for Crypto assets).
* - Schema version `0x0004` corresponds to report version 4 (for Real World Assets).
* - Validates that the report version is either 3 or 4; reverts with `InvalidReportVersion` otherwise.
* - Retrieves the fee manager and reward manager contracts.
* - Calculates the fee required for report verification using the fee manager.
* - Approves the reward manager to spend the calculated fee amount.
* - Verifies the report via the VerifierProxy contract.
* - Decodes the verified report data into the appropriate report struct (`ReportV3` or `ReportV4`) based on the report version.
* - Emits a `DecodedPrice` event with the price extracted from the verified report.
* - Updates the `lastDecodedPrice` state variable with the price from the verified report.
* @param unverifiedReport The encoded report data to be verified, including the signed report and metadata.
* @custom:reverts InvalidReportVersion(uint8 version) Thrown when an unsupported report version is provided.
*/
function verifyReport(bytes memory unverifiedReport) external {
// Retrieve fee manager and reward manager
IFeeManager feeManager = IFeeManager(
address(s_verifierProxy.s_feeManager())
);
IRewardManager rewardManager = IRewardManager(
address(feeManager.i_rewardManager())
);
// Decode unverified report to extract report data
(, bytes memory reportData) = abi.decode(
unverifiedReport,
(bytes32[3], bytes)
);
// Extract report version from reportData
uint16 reportVersion = (uint16(uint8(reportData[0])) << 8) |
uint16(uint8(reportData[1]));
// Validate report version
if (reportVersion != 3 && reportVersion != 4) {
revert InvalidReportVersion(uint8(reportVersion));
}
// Set the fee token address (LINK in this case)
address feeTokenAddress = feeManager.i_linkAddress();
// Calculate the fee required for report verification
(Common.Asset memory fee, , ) = feeManager.getFeeAndReward(
address(this),
reportData,
feeTokenAddress
);
// Approve rewardManager to spend this contract's balance in fees
IERC20(feeTokenAddress).approve(address(rewardManager), fee.amount);
// Verify the report through the VerifierProxy
bytes memory verifiedReportData = s_verifierProxy.verify(
unverifiedReport,
abi.encode(feeTokenAddress)
);
// Decode verified report data into the appropriate Report struct based on reportVersion
if (reportVersion == 3) {
// v3 report schema
ReportV3 memory verifiedReport = abi.decode(
verifiedReportData,
(ReportV3)
);
// Log price from the verified report
emit DecodedPrice(verifiedReport.price);
// Store the price from the report
lastDecodedPrice = verifiedReport.price;
} else if (reportVersion == 4) {
// v4 report schema
ReportV4 memory verifiedReport = abi.decode(
verifiedReportData,
(ReportV4)
);
// Log price from the verified report
emit DecodedPrice(verifiedReport.price);
// Store the price from the report
lastDecodedPrice = verifiedReport.price;
}
}
/**
* @notice Withdraws all tokens of a specific ERC20 token type to a beneficiary address.
* @dev Utilizes SafeERC20's safeTransfer for secure token transfer. Reverts if the contract's balance of the specified token is zero.
* @param _beneficiary Address to which the tokens will be sent. Must not be the zero address.
* @param _token Address of the ERC20 token to be withdrawn. Must be a valid ERC20 token contract.
*/
function withdrawToken(
address _beneficiary,
address _token
) public onlyOwner {
// Retrieve the balance of this contract for the specified token
uint256 amount = IERC20(_token).balanceOf(address(this));
// Revert if there is nothing to withdraw
if (amount == 0) revert NothingToWithdraw();
// Transfer the tokens to the beneficiary
IERC20(_token).safeTransfer(_beneficiary, amount);
}
}