aave-protocol-v2/contracts/misc/ChainlinkProxyPriceProvider.sol

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// SPDX-License-Identifier: agpl-3.0
pragma solidity ^0.6.8;
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import '@openzeppelin/contracts/access/Ownable.sol';
import '@openzeppelin/contracts/token/ERC20/IERC20.sol';
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import '../interfaces/IPriceOracleGetter.sol';
import '../interfaces/IChainlinkAggregator.sol';
import '../libraries/UniversalERC20.sol';
/// @title ChainlinkProxyPriceProvider
/// @author Aave
/// @notice Proxy smart contract to get the price of an asset from a price source, with Chainlink Aggregator
/// smart contracts as primary option
/// - If the returned price by a Chainlink aggregator is <= 0, the call is forwarded to a fallbackOracle
/// - Owned by the Aave governance system, allowed to add sources for assets, replace them
/// and change the fallbackOracle
contract ChainlinkProxyPriceProvider is IPriceOracleGetter, Ownable {
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using UniversalERC20 for IERC20;
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event AssetSourceUpdated(address indexed asset, address indexed source);
event FallbackOracleUpdated(address indexed fallbackOracle);
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mapping(address => IChainlinkAggregator) private assetsSources;
IPriceOracleGetter private fallbackOracle;
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/// @notice Constructor
/// @param _assets The addresses of the assets
/// @param _sources The address of the source of each asset
/// @param _fallbackOracle The address of the fallback oracle to use if the data of an
/// aggregator is not consistent
constructor(
address[] memory _assets,
address[] memory _sources,
address _fallbackOracle
) public {
internalSetFallbackOracle(_fallbackOracle);
internalSetAssetsSources(_assets, _sources);
}
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/// @notice External function called by the Aave governance to set or replace sources of assets
/// @param _assets The addresses of the assets
/// @param _sources The address of the source of each asset
function setAssetSources(address[] calldata _assets, address[] calldata _sources)
external
onlyOwner
{
internalSetAssetsSources(_assets, _sources);
}
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/// @notice Sets the fallbackOracle
/// - Callable only by the Aave governance
/// @param _fallbackOracle The address of the fallbackOracle
function setFallbackOracle(address _fallbackOracle) external onlyOwner {
internalSetFallbackOracle(_fallbackOracle);
}
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/// @notice Internal function to set the sources for each asset
/// @param _assets The addresses of the assets
/// @param _sources The address of the source of each asset
function internalSetAssetsSources(address[] memory _assets, address[] memory _sources) internal {
require(_assets.length == _sources.length, 'INCONSISTENT_PARAMS_LENGTH');
for (uint256 i = 0; i < _assets.length; i++) {
assetsSources[_assets[i]] = IChainlinkAggregator(_sources[i]);
emit AssetSourceUpdated(_assets[i], _sources[i]);
}
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}
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/// @notice Internal function to set the fallbackOracle
/// @param _fallbackOracle The address of the fallbackOracle
function internalSetFallbackOracle(address _fallbackOracle) internal {
fallbackOracle = IPriceOracleGetter(_fallbackOracle);
emit FallbackOracleUpdated(_fallbackOracle);
}
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/// @notice Gets an asset price by address
/// @param _asset The asset address
function getAssetPrice(address _asset) public override view returns (uint256) {
IChainlinkAggregator source = assetsSources[_asset];
if (IERC20(_asset).isETH()) {
return 1 ether;
} else {
// If there is no registered source for the asset, call the fallbackOracle
if (address(source) == address(0)) {
return IPriceOracleGetter(fallbackOracle).getAssetPrice(_asset);
} else {
int256 _price = IChainlinkAggregator(source).latestAnswer();
if (_price > 0) {
return uint256(_price);
} else {
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return IPriceOracleGetter(fallbackOracle).getAssetPrice(_asset);
}
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}
}
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}
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/// @notice Gets a list of prices from a list of assets addresses
/// @param _assets The list of assets addresses
function getAssetsPrices(address[] calldata _assets) external view returns (uint256[] memory) {
uint256[] memory prices = new uint256[](_assets.length);
for (uint256 i = 0; i < _assets.length; i++) {
prices[i] = getAssetPrice(_assets[i]);
}
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return prices;
}
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/// @notice Gets the address of the source for an asset address
/// @param _asset The address of the asset
/// @return address The address of the source
function getSourceOfAsset(address _asset) external view returns (address) {
return address(assetsSources[_asset]);
}
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/// @notice Gets the address of the fallback oracle
/// @return address The addres of the fallback oracle
function getFallbackOracle() external view returns (address) {
return address(fallbackOracle);
}
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}