ResilientOracle

ResilientOracle

The Resilient Oracle is the main contract that the protocol uses to fetch prices of assets.

DeFi protocols are vulnerable to price oracle failures including oracle manipulation and incorrectly reported prices. If only one oracle is used, this creates a single point of failure and opens a vector for attacking the protocol.

The Resilient Oracle uses multiple sources and fallback mechanisms to provide accurate prices and protect the protocol from oracle attacks. Currently it includes integrations with Chainlink, RedStone, Pyth and Binance Oracle oracles.

For every market (vToken) we configure the main, pivot and fallback oracles. The oracles are configured per vToken's underlying asset address. The main oracle oracle is the most trustworthy price source, the pivot oracle is used as a loose sanity checker and the fallback oracle is used as a backup price source.

To validate prices returned from two oracles, we use an upper and lower bound ratio that is set for every market. The upper bound ratio represents the deviation between reported price (the price that’s being validated) and the anchor price (the price we are validating against) above which the reported price will be invalidated. The lower bound ratio presents the deviation between reported price and anchor price below which the reported price will be invalidated. So for oracle price to be considered valid the below statement should be true:

anchorRatio = anchorPrice/reporterPrice
isValid = anchorRatio <= upperBoundAnchorRatio && anchorRatio >= lowerBoundAnchorRatio

In most cases, Chainlink is used as the main oracle, RedStone or Pyth oracles are used as the pivot oracle depending on which supports the given market and Binance oracle is used as the fallback oracle. For some markets we may use RedStone or Pyth as the main oracle if the token price is not supported by Chainlink or Binance oracles.

For a fetched price to be valid it must be positive and not stagnant. If the price is invalid then we consider the oracle to be stagnant and treat it like it's disabled.

Solidity API

enum OracleRole {
  MAIN,
  PIVOT,
  FALLBACK
}
struct TokenConfig {
  address asset;
  address[3] oracles;
  bool[3] enableFlagsForOracles;
}

vBnb

vBNB address

address vBnb

vai

VAI address

address vai

BNB_ADDR

Set this as asset address for BNB. This is the underlying for vBNB

address BNB_ADDR

boundValidator

Bound validator contract address

contract BoundValidatorInterface boundValidator

constructor

Constructor for the implementation contract. Sets immutable variables.

constructor(address vBnbAddress, address vaiAddress, contract BoundValidatorInterface _boundValidator) public

Parameters

NameTypeDescription

vBnbAddress

address

The address of the vBNB

vaiAddress

address

The address of the VAI

_boundValidator

contract BoundValidatorInterface

Address of the bound validator contract

initialize

Initializes the contract admin and sets the BoundValidator contract address

function initialize(address accessControlManager_) external

Parameters

NameTypeDescription

accessControlManager_

address

Address of the access control manager contract

pause

Pauses oracle

function pause() external

⛔️ Access Requirements

  • Only Governance

unpause

Unpauses oracle

function unpause() external

⛔️ Access Requirements

  • Only Governance

setTokenConfigs

Batch sets token configs

function setTokenConfigs(struct ResilientOracle.TokenConfig[] tokenConfigs_) external

Parameters

NameTypeDescription

tokenConfigs_

struct ResilientOracle.TokenConfig[]

Token config array

⛔️ Access Requirements

  • Only Governance

❌ Errors

  • Throws a length error if the length of the token configs array is 0

setOracle

Sets oracle for a given asset and role.

function setOracle(address asset, address oracle, enum ResilientOracle.OracleRole role) external

Parameters

NameTypeDescription

asset

address

Asset address

oracle

address

Oracle address

role

enum ResilientOracle.OracleRole

Oracle role

📅 Events

  • Emits OracleSet event with asset address, oracle address and role of the oracle for the asset

⛔️ Access Requirements

  • Only Governance

❌ Errors

  • Null address error if main-role oracle address is null

  • NotNullAddress error is thrown if asset address is null

  • TokenConfigExistance error is thrown if token config is not set

enableOracle

Enables/ disables oracle for the input asset. Token config for the input asset must exist

function enableOracle(address asset, enum ResilientOracle.OracleRole role, bool enable) external

Parameters

NameTypeDescription

asset

address

Asset address

role

enum ResilientOracle.OracleRole

Oracle role

enable

bool

Enabled boolean of the oracle

⛔️ Access Requirements

  • Only Governance

❌ Errors

  • NotNullAddress error is thrown if asset address is null

  • TokenConfigExistance error is thrown if token config is not set

updatePrice

Updates the TWAP pivot oracle price.

function updatePrice(address vToken) external

Parameters

NameTypeDescription

vToken

address

vToken address

updateAssetPrice

Updates the pivot oracle price. Currently using TWAP

function updateAssetPrice(address asset) external

Parameters

NameTypeDescription

asset

address

asset address

getUnderlyingPrice

Gets price of the underlying asset for a given vToken. Validation flow:

  • Check if the oracle is paused globally

  • Validate price from main oracle against pivot oracle

  • Validate price from fallback oracle against pivot oracle if the first validation failed

  • Validate price from main oracle against fallback oracle if the second validation failed In the case that the pivot oracle is not available but main price is available and validation is successful, main oracle price is returned.

function getUnderlyingPrice(address vToken) external view returns (uint256)

Parameters

NameTypeDescription

vToken

address

vToken address

Return Values

NameTypeDescription

[0]

uint256

price USD price in scaled decimal places.

❌ Errors

  • Paused error is thrown when resilent oracle is paused

  • Invalid resilient oracle price error is thrown if fetched prices from oracle is invalid

getPrice

Gets price of the asset

function getPrice(address asset) external view returns (uint256)

Parameters

NameTypeDescription

asset

address

asset address

Return Values

NameTypeDescription

[0]

uint256

price USD price in scaled decimal places.

❌ Errors

  • Paused error is thrown when resilent oracle is paused

  • Invalid resilient oracle price error is thrown if fetched prices from oracle is invalid

setTokenConfig

Sets/resets single token configs.

function setTokenConfig(struct ResilientOracle.TokenConfig tokenConfig) public

Parameters

NameTypeDescription

tokenConfig

struct ResilientOracle.TokenConfig

Token config struct

📅 Events

  • Emits TokenConfigAdded event when the asset config is set successfully by the authorized account

⛔️ Access Requirements

  • Only Governance

❌ Errors

  • NotNullAddress is thrown if asset address is null

  • NotNullAddress is thrown if main-role oracle address for asset is null

getOracle

Gets oracle and enabled status by asset address

function getOracle(address asset, enum ResilientOracle.OracleRole role) public view returns (address oracle, bool enabled)

Parameters

NameTypeDescription

asset

address

asset address

role

enum ResilientOracle.OracleRole

Oracle role

Return Values

NameTypeDescription

oracle

address

Oracle address based on role

enabled

bool

Enabled flag of the oracle based on token config

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