SOV-5246: enable usdt0 lending pool

Author: cwsnt

contracts/feeds/USDT0PriceFeed.sol

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+pragma solidity 0.5.17;
+
+/**
+ * @title USDT0 Price Feed Wrapper
+ * @notice Wraps the Redstone USDT price feed and normalizes from 8 decimals to 18 decimals
+ * for compatibility with Sovryn's PriceFeeds contract.
+ *
+ * Redstone USDT Price Feed on RSK Mainnet: 0x09639692ce6Ff12a06cA3AE9a24B3aAE4cD80dc8
+ * Contract: RootstockPriceFeedUsdtWithoutRoundsV1
+ * - latestRoundData() returns (roundId, answer, startedAt, updatedAt, answeredInRound)
+ * - answer is in 8 decimals
+ * - decimals() returns 8
+ *
+ * This wrapper:
+ * 1. Validates price data is not stale or invalid
+ * 2. Scales the price from 8 decimals to 18 decimals for Sovryn compatibility
+ */
+
+interface IRedstoneOracle {
+    function latestRoundData()
+        external
+        view
+        returns (
+            uint80 roundId,
+            int256 answer,
+            uint256 startedAt,
+            uint256 updatedAt,
+            uint80 answeredInRound
+        );
+    function decimals() external view returns (uint8);
+}
+
+contract USDT0PriceFeed {
+    IRedstoneOracle public oracle;
+
+    /// @dev Maximum acceptable age for price data (24 hours)
+    /// After this time, price is considered stale (referred to the heartbet of redstone)
+    uint256 public constant MAX_PRICE_AGE = 24 hours;
+
+    /**
+     * @notice Constructor
+     * @param _oracle The address of the Redstone USDT price feed (0x09639692ce6Ff12a06cA3AE9a24B3aAE4cD80dc8)
+     */
+    constructor(address _oracle) public {
+        require(_oracle != address(0), "Invalid oracle address");
+        oracle = IRedstoneOracle(_oracle);
+    }
+
+    /**
+     * @notice Get the latest price from Redstone oracle and scale to 18 decimals
+     * @dev Performs validation checks on the oracle data:
+     *      - Price must be greater than 0
+     *      - Price must not be stale (updated within MAX_PRICE_AGE)
+     *      - Round must be complete (answeredInRound >= roundId)
+     *
+     *      Redstone returns 8 decimals (e.g., 99937000 = $0.99937)
+     *      We scale to 18 decimals (e.g., 999370000000000000 = $0.99937)
+     *
+     * @return The validated price with 18 decimals
+     */
+    function latestAnswer() external view returns (uint256) {
+        (uint80 roundId, int256 answer, , uint256 updatedAt, uint80 answeredInRound) = oracle
+            .latestRoundData();
+
+        // Validate price data
+        require(answer > 0, "Invalid price: answer <= 0");
+        require(updatedAt > 0, "Invalid price: updatedAt = 0");
+        require(answeredInRound >= roundId, "Stale price: round not complete");
+        require(block.timestamp - updatedAt <= MAX_PRICE_AGE, "Stale price: too old");
+
+        uint256 price = uint256(answer);
+        uint8 oracleDecimals = oracle.decimals();
+
+        // Scale from oracle decimals to 18 decimals
+        // price * 10^(18 - oracleDecimals)
+        if (oracleDecimals < 18) {
+            return price * (10 ** (18 - uint256(oracleDecimals)));
+        } else if (oracleDecimals > 18) {
+            return price / (10 ** (uint256(oracleDecimals) - 18));
+        } else {
+            return price;
+        }
+    }
+}

contracts/mockup/MockRedstoneOracle.sol

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+/**
+ * Mock Redstone Oracle for testing USDT0PriceFeed wrapper
+ * Simulates Redstone's USDT price feed which returns 8 decimals
+ * Implements latestRoundData() for realistic testing
+ */
+
+pragma solidity 0.5.17;
+
+contract MockRedstoneOracle {
+    int256 private price;
+    uint80 private currentRound;
+    uint256 private lastUpdateTime;
+
+    constructor() public {
+        price = 100000000; // $1.00 with 8 decimals
+        currentRound = 1;
+        lastUpdateTime = block.timestamp;
+    }
+
+    function setPrice(int256 _price) external {
+        price = _price;
+        currentRound++;
+        lastUpdateTime = block.timestamp;
+    }
+
+    function setUpdatedAt(uint256 _timestamp) external {
+        lastUpdateTime = _timestamp;
+    }
+
+    function latestRoundData()
+        external
+        view
+        returns (
+            uint80 roundId,
+            int256 answer,
+            uint256 startedAt,
+            uint256 updatedAt,
+            uint80 answeredInRound
+        )
+    {
+        return (currentRound, price, lastUpdateTime, lastUpdateTime, currentRound);
+    }
+
+    /// @dev Always returns 8 decimals to match real Redstone oracle
+    function decimals() external pure returns (uint8) {
+        return 8;
+    }
+}

deployment/deploy/2170-deploy-USDT0PriceFeed.js

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+const hre = require("hardhat");
+const { setDeploymentMetaData } = require("../helpers/helpers");
+
+/**
+ * Deploy USDT0PriceFeed wrapper contract
+ *
+ * This wrapper:
+ * 1. Normalizes Redstone USDT price feed from 8 decimals to 18 decimals
+ * 2. Validates price data to prevent stale/invalid prices (security-critical)
+ *
+ * Security features:
+ * - Uses latestRoundData() for full validation
+ * - Checks answer > 0 (prevents zero price exploits)
+ * - Validates freshness (24-hour staleness check)
+ * - Verifies round completion (prevents incomplete data usage)
+ *
+ * Redstone USDT Price Feed on RSK Mainnet: 0x09639692ce6Ff12a06cA3AE9a24B3aAE4cD80dc8
+ */
+module.exports = async (hre) => {
+    const { deployments, getNamedAccounts } = hre;
+    const { deploy, get } = deployments;
+    const { deployer } = await getNamedAccounts();
+
+    // Get Redstone USDT oracle from deployment
+    const redstoneOracle = await get("RedStoneUSDT0Oracle");
+
+    console.log("\n--- Deploying USDT0PriceFeed Wrapper ---");
+    console.log(`Deployer: ${deployer}`);
+    console.log(`Redstone Oracle: ${redstoneOracle.address}`);
+
+    const usdt0PriceFeed = await deploy("USDT0PriceFeeds", {
+        contract: "USDT0PriceFeed",
+        from: deployer,
+        args: [redstoneOracle.address],
+        log: true,
+        skipIfAlreadyDeployed: true,
+    });
+
+    if (usdt0PriceFeed.newlyDeployed) {
+        console.log(`✅ USDT0PriceFeed deployed at: ${usdt0PriceFeed.address}`);
+
+        // Verify the wrapper is working correctly
+        const USDT0PriceFeed = await hre.ethers.getContractAt(
+            "USDT0PriceFeed",
+            usdt0PriceFeed.address
+        );
+
+        try {
+            const price = await USDT0PriceFeed.latestAnswer();
+            console.log(`   Price (18 decimals): ${hre.ethers.utils.formatEther(price)}`);
+            console.log(`   Raw value: ${price.toString()}`);
+
+            // Expected: ~999370000000000000 (0.99937 with 18 decimals)
+            const expectedMin = hre.ethers.utils.parseEther("0.9"); // $0.90
+            const expectedMax = hre.ethers.utils.parseEther("1.1"); // $1.10
+
+            if (price.gte(expectedMin) && price.lte(expectedMax)) {
+                console.log("   ✅ Price feed is working correctly (within expected range)");
+            } else {
+                console.log("   ⚠️  Warning: Price is outside expected range ($0.90 - $1.10)");
+            }
+        } catch (error) {
+            console.log(`   ⚠️  Warning: Could not verify price feed: ${error.message}`);
+        }
+
+        await setDeploymentMetaData("USDT0PriceFeeds", {
+            contractAddress: usdt0PriceFeed.address,
+            description: "USDT0 Price Feed Wrapper (Redstone -> 18 decimals)",
+            redstoneOracle: redstoneOracle.address,
+        });
+    } else {
+        console.log(`USDT0PriceFeed already deployed at: ${usdt0PriceFeed.address}`);
+    }
+};
+
+module.exports.tags = ["USDT0PriceFeed", "PriceFeeds"];
+module.exports.dependencies = ["RedStoneUSDT0Oracle"];