Merge pull request #65 from morpho-org/feat/wsteth-oracle

wstETH/ETH oracle using exchange rate only

Author: MathisGD

src/ChainlinkOracle.sol renamed to src/morpho-chainlink-v1/ChainlinkOracle.sol

@@ -2,12 +2,12 @@
 pragma solidity 0.8.21;
 
 import {IChainlinkOracle} from "./interfaces/IChainlinkOracle.sol";
-import {IOracle} from "../lib/morpho-blue/src/interfaces/IOracle.sol";
+import {IOracle} from "../../lib/morpho-blue/src/interfaces/IOracle.sol";
 
 import {AggregatorV3Interface, ChainlinkDataFeedLib} from "./libraries/ChainlinkDataFeedLib.sol";
 import {IERC4626, VaultLib} from "./libraries/VaultLib.sol";
 import {ErrorsLib} from "./libraries/ErrorsLib.sol";
-import {Math} from "../lib/openzeppelin-contracts/contracts/utils/math/Math.sol";
+import {Math} from "../../lib/openzeppelin-contracts/contracts/utils/math/Math.sol";
 
 /// @title ChainlinkOracle
 /// @author Morpho Labs

src/interfaces/AggregatorV3Interface.sol renamed to src/morpho-chainlink-v1/interfaces/AggregatorV3Interface.sol

@@ -3,7 +3,7 @@ pragma solidity >=0.5.0;
 
 import {IERC4626} from "./IERC4626.sol";
 import {AggregatorV3Interface} from "./AggregatorV3Interface.sol";
-import {IOracle} from "../../lib/morpho-blue/src/interfaces/IOracle.sol";
+import {IOracle} from "../../../lib/morpho-blue/src/interfaces/IOracle.sol";
 
 /// @title IChainlinkOracle
 /// @author Morpho Labs

src/interfaces/IChainlinkOracle.sol renamed to src/morpho-chainlink-v1/interfaces/IChainlinkOracle.sol

@@ -0,0 +1,30 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+pragma solidity 0.8.21;
+
+import {IStEth} from "./interfaces/IStEth.sol";
+import {MinimalAggregatorV3Interface} from "./interfaces/MinimalAggregatorV3Interface.sol";
+
+/// @title WstEthStEthExchangeRateChainlinkAdapter
+/// @author Morpho Labs
+/// @custom:contact security@morpho.org
+/// @notice wstETH/stETH exchange rate price feed.
+/// @dev This contract should only be deployed on Ethereum and used as a price feed for Morpho oracles.
+contract WstEthStEthExchangeRateChainlinkAdapter is MinimalAggregatorV3Interface {
+    /// @inheritdoc MinimalAggregatorV3Interface
+    // @dev The calculated price has 18 decimals precision, whatever the value of `decimals`.
+    uint8 public constant decimals = 18;
+
+    /// @notice The description of the price feed.
+    string public constant description = "wstETH/stETH exchange rate";
+
+    /// @notice The address of stETH on Ethereum.
+    IStEth public constant ST_ETH = IStEth(0xae7ab96520DE3A18E5e111B5EaAb095312D7fE84);
+
+    /// @inheritdoc MinimalAggregatorV3Interface
+    /// @dev Returns zero for roundId, startedAt, updatedAt and answeredInRound.
+    /// @dev Silently overflows if `getPooledEthByShares`'s return value is greater than `type(int256).max`.
+    function latestRoundData() external view returns (uint80, int256, uint256, uint256, uint80) {
+        // It is assumed that `getPooledEthByShares` returns a price with 18 decimals precision.
+        return (0, int256(ST_ETH.getPooledEthByShares(1 ether)), 0, 0, 0);
+    }
+}

src/interfaces/IERC4626.sol renamed to src/morpho-chainlink-v1/interfaces/IERC4626.sol

@@ -0,0 +1,6 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+pragma solidity >=0.5.0;
+
+interface IStEth {
+    function getPooledEthByShares(uint256) external view returns (uint256);
+}

src/libraries/ChainlinkDataFeedLib.sol renamed to src/morpho-chainlink-v1/libraries/ChainlinkDataFeedLib.sol

@@ -0,0 +1,17 @@
+// SPDX-License-Identifier: MIT
+pragma solidity >=0.5.0;
+
+/// @dev Inspired by
+/// https://github.com/smartcontractkit/chainlink/blob/master/contracts/src/v0.8/shared/interfaces/AggregatorV3Interface.sol
+/// @dev This is the minimal feed interface required by `MorphoChainlinkOracleV2`.
+interface MinimalAggregatorV3Interface {
+    /// @notice Returns the precision of the feed.
+    function decimals() external view returns (uint8);
+
+    /// @notice Returns Chainlink's `latestRoundData` return values.
+    /// @notice Only the `answer` field is used by `MorphoChainlinkOracleV2`.
+    function latestRoundData()
+        external
+        view
+        returns (uint80 roundId, int256 answer, uint256 startedAt, uint256 updatedAt, uint80 answeredInRound);
+}