BackendPriceProvider

Overview

License: MIT

contract BackendPriceProvider is PriceProvider, Initializable, AccessControlUpgradeable

The BackendPriceProvider contract is the contract that provides prices for assets using a trusted backend.

Structs info

BackendMetadata

struct BackendMetadata {
	bool isListed;
	bool isActive;
}

Events info

GrantTrustedBackendRole

event GrantTrustedBackendRole(address indexed newTrustedBackend)

Emitted when the trusted backend role is granted to a new trusted backend.

Parameters:

Name	Type	Description
newTrustedBackend	address	The address of the new trusted backend.

RevokeTrustedBackendRole

event RevokeTrustedBackendRole(address indexed trustedBackend)

Emitted when the trusted backend role is revoked from a trusted backend.

Parameters:

Name	Type	Description
trustedBackend	address	The address of the trusted backend to revoke the role from.

SetToken

event SetToken(address indexed token)

Emitted when a new token is set as the price provider.

Parameters:

Name	Type	Description
token	address	The address of the token set as the price provider.

ChangeActive

event ChangeActive(address indexed token, bool active)

Emitted when the active status of a token is changed.

Parameters:

Name	Type	Description
token	address	The address of the token to change the active status for.
active	bool	The new active status for the token.

Constants info

TRUSTED_BACKEND_ROLE (0xec39004b)

bytes32 constant TRUSTED_BACKEND_ROLE = keccak256("TRUSTED_BACKEND_ROLE")

DESCRIPTION (0xf1ae8856)

string constant DESCRIPTION = "Price provider that uses trusted backend"

State variables info

usdDecimals (0x66a4b6c0)

uint8 usdDecimals

backendMetadata (0xa980ff07)

mapping(address => struct BackendPriceProvider.BackendMetadata) backendMetadata

Modifiers info

onlyAdmin

modifier onlyAdmin()

Modifier to restrict access to only the contract admin.

onlyTrustedBackend

modifier onlyTrustedBackend()

Modifier to restrict access to only the trusted backend.

Functions info

initialize (0x8129fc1c)

function initialize() public initializer

Initializes the contract by setting up the access control roles and the number of decimals for the USD price.

grantTrustedBackendRole (0x5585d4de)

function grantTrustedBackendRole(address newTrustedBackend) public onlyAdmin

Grants the TRUSTED_BACKEND_ROLE to a new trusted backend address.

Parameters:

Name	Type	Description
newTrustedBackend	address	The address of the new trusted backend.

revokeTrustedBackendRole (0xabc36444)

function revokeTrustedBackendRole(address trustedBackend) public onlyAdmin

Revokes the trusted backend role from the specified address.

Parameters:

Name	Type	Description
trustedBackend	address	The address of the trusted backend to revoke the role from.

setToken (0x144fa6d7)

function setToken(address token) public onlyTrustedBackend

Sets the token as listed and active in the backend metadata.

Parameters:

Name	Type	Description
token	address	The address of the token to be set.

changeActive (0x258a4532)

function changeActive(
    address token,
    bool active
) public override onlyTrustedBackend

Changes the active status of a token in the backend metadata.

Parameters:

Name	Type	Description
token	address	The address of the token to change the active status for.
active	bool	The new active status for the token.

getMessageHash (0xd2b0737b)

function getMessageHash(
    address token,
    uint256 priceMantissa,
    uint256 validTo
) public pure returns (bytes32)

1. Step. Backend creates offchain data and get hash of this data. This data calls message.

returns the keccak256 of concatenated input data

Parameters:

Name	Type	Description
token	address	the address of asset
priceMantissa	uint256	the price of asset that include decimals
validTo	uint256	the unix timestamp in seconds that define the validity of given price to validTo timestamp

getEthSignedMessageHash (0xfa540801)

function getEthSignedMessageHash(
    bytes32 messageHash
) public pure returns (bytes32)

2. Step. Backend formatting the message and get hash of this message.

Returns the keccak256 of formatted message

Parameters:

Name	Type	Description
messageHash	bytes32	the keccak256 of message

verify (0x0deea608)

function verify(
    address token,
    uint256 priceMantissa,
    uint256 validTo,
    bytes memory signature
) public view returns (bool)

4. Step. Smart contract verify the message (tuple)

Returns true if the message is signed by trusted backend. Else returns false.

Parameters:

Name	Type	Description
token	address	the address of asset
priceMantissa	uint256	the price of asset that include decimals
validTo	uint256	the unix timestamp in seconds that define the validity of given price to validTo timestamp
signature	bytes	the sign of message.

recoverSigner (0x97aba7f9)

function recoverSigner(
    bytes32 ethSignedMessageHash,
    bytes memory signature
) public pure returns (address)

Recovers the signer of a message signed with the Ethereum signature scheme.

Parameters:

Name	Type	Description
ethSignedMessageHash	bytes32	The hash of the signed message.
signature	bytes	The signature of the message.

Return values:

Name	Type	Description
[0]	address	The address of the signer.

isListed (0xf794062e)

function isListed(address token) public view override returns (bool)

Returns whether a token is listed on the backend price provider.

Parameters:

Name	Type	Description
token	address	The address of the token to check.

Return values:

Name	Type	Description
[0]	bool	A boolean indicating whether the token is listed.

isActive (0x9f8a13d7)

function isActive(address token) public view override returns (bool)

Returns whether a token is active or not.

Parameters:

Name	Type	Description
token	address	The address of the token to check.

Return values:

Name	Type	Description
[0]	bool	A boolean indicating whether the token is active or not.

getPrice (0x41976e09)

function getPrice(
    address token
) public pure override returns (uint256 price, uint8 priceDecimals)

Returns the latest asset price and price decimals.

Parameters:

Name	Type	Description
token	address	the token address.

getPriceSigned (0x19ed931d)

function getPriceSigned(
    address token,
    uint256 priceMantissa,
    uint256 validTo,
    bytes memory signature
) public view override returns (uint256 _priceMantissa, uint8 priceDecimals)

Returns the price of a token as a signed integer, along with the number of decimals for the price.

Parameters:

Name	Type	Description
token	address	The address of the token.
priceMantissa	uint256	The price of the token as a mantissa.
validTo	uint256	The timestamp until which the price is valid.
signature	bytes	The signature of the price provided by a moderator.

Return values:

Name	Type	Description
_priceMantissa	uint256	The price of the token as a mantissa.
priceDecimals	uint8	The number of decimals for the price.

getEvaluation (0x81fd01ea)

function getEvaluation(
    address token,
    uint256 tokenAmount
) public pure override returns (uint256 evaluation)

This function is deprecated. Use getEvaluationSigned(...) instead. This function is used to get the evaluation of a token with a given amount.

Parameters:

Name	Type	Description
token	address	The address of the token to be evaluated.
tokenAmount	uint256	The amount of the token to be evaluated.

Return values:

Name	Type	Description
evaluation	uint256	The evaluation of the token with the given amount.

getEvaluationSigned (0xa5c68226)

function getEvaluationSigned(
    address token,
    uint256 tokenAmount,
    uint256 priceMantissa,
    uint256 validTo,
    bytes memory signature
) public view override returns (uint256 evaluation)

ReturnS the evaluation in $ of tokenAmount with signed price.

Parameters:

Name	Type	Description
token	address	the address of token to get evaluation in $.
tokenAmount	uint256	the amount of token to get evaluation. Amount is scaled by 10 in power token decimals.
priceMantissa	uint256	the price multiplied by priceDecimals. The dimension of priceMantissa should be $/token.
validTo	uint256	the timestamp in seconds, when price is gonna be not valid.
signature	bytes	the ECDSA sign on eliptic curve secp256k1.

getPriceDecimals (0x1b30aafc)

function getPriceDecimals() public view override returns (uint8)

Returns the number of decimals used for the price returned by this price provider.

Return values:

Name	Type	Description
[0]	uint8	The number of decimals used for the price returned by this price provider.