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# SelfPermit

[Git Source](https://github.com/yearn/Yearn-ERC4626-Router/blob/68165774ec8858b43db24620756402def14b7ec1/src/external/SelfPermit.sol)

**Inherits:**
[ISelfPermit](https://github.com/yearn/Yearn-ERC4626-Router/blob/68165774ec8858b43db24620756402def14b7ec1/src/external/interfaces/ISelfPermit.sol)

Functionality to call permit on any EIP-2612-compliant token for use in the route

*These functions are expected to be embedded in multicalls to allow EOAs to approve a contract and call a function
that requires an approval in a single transaction.*

## Functions

### selfPermit

Permits this contract to spend a given token from `msg.sender`

*The `owner` is always msg.sender and the `spender` is always address(this).*

```solidity
function selfPermit(address token, uint256 value, uint256 deadline, uint8 v, bytes32 r, bytes32 s)
    public
    payable
    override;
```

**Parameters**

|Name|Type|Description|
|----|----|-----------|
|`token`|`address`|The address of the token spent|
|`value`|`uint256`|The amount that can be spent of token|
|`deadline`|`uint256`|A timestamp, the current blocktime must be less than or equal to this timestamp|
|`v`|`uint8`|Must produce valid secp256k1 signature from the holder along with `r` and `s`|
|`r`|`bytes32`|Must produce valid secp256k1 signature from the holder along with `v` and `s`|
|`s`|`bytes32`|Must produce valid secp256k1 signature from the holder along with `r` and `v`|

### selfPermitIfNecessary

Permits this contract to spend a given token from `msg.sender`

*The `owner` is always msg.sender and the `spender` is always address(this).
Can be used instead of #selfPermit to prevent calls from failing due to a frontrun of a call to #selfPermit*

```solidity
function selfPermitIfNecessary(address token, uint256 value, uint256 deadline, uint8 v, bytes32 r, bytes32 s)
    external
    payable
    override;
```

**Parameters**

|Name|Type|Description|
|----|----|-----------|
|`token`|`address`|The address of the token spent|
|`value`|`uint256`|The amount that can be spent of token|
|`deadline`|`uint256`|A timestamp, the current blocktime must be less than or equal to this timestamp|
|`v`|`uint8`|Must produce valid secp256k1 signature from the holder along with `r` and `s`|
|`r`|`bytes32`|Must produce valid secp256k1 signature from the holder along with `v` and `s`|
|`s`|`bytes32`|Must produce valid secp256k1 signature from the holder along with `r` and `v`|

### selfPermitAllowed

Permits this contract to spend the sender's tokens for permit signatures that have the `allowed` parameter

*The `owner` is always msg.sender and the `spender` is always address(this)*

```solidity
function selfPermitAllowed(address token, uint256 nonce, uint256 expiry, uint8 v, bytes32 r, bytes32 s)
    public
    payable
    override;
```

**Parameters**

|Name|Type|Description|
|----|----|-----------|
|`token`|`address`|The address of the token spent|
|`nonce`|`uint256`|The current nonce of the owner|
|`expiry`|`uint256`|The timestamp at which the permit is no longer valid|
|`v`|`uint8`|Must produce valid secp256k1 signature from the holder along with `r` and `s`|
|`r`|`bytes32`|Must produce valid secp256k1 signature from the holder along with `v` and `s`|
|`s`|`bytes32`|Must produce valid secp256k1 signature from the holder along with `r` and `v`|

### selfPermitAllowedIfNecessary

Permits this contract to spend the sender's tokens for permit signatures that have the `allowed` parameter

*The `owner` is always msg.sender and the `spender` is always address(this)
Can be used instead of #selfPermitAllowed to prevent calls from failing due to a frontrun of a call to #selfPermitAllowed.*

```solidity
function selfPermitAllowedIfNecessary(address token, uint256 nonce, uint256 expiry, uint8 v, bytes32 r, bytes32 s)
    external
    payable
    override;
```

**Parameters**

|Name|Type|Description|
|----|----|-----------|
|`token`|`address`|The address of the token spent|
|`nonce`|`uint256`|The current nonce of the owner|
|`expiry`|`uint256`|The timestamp at which the permit is no longer valid|
|`v`|`uint8`|Must produce valid secp256k1 signature from the holder along with `r` and `s`|
|`r`|`bytes32`|Must produce valid secp256k1 signature from the holder along with `v` and `s`|
|`s`|`bytes32`|Must produce valid secp256k1 signature from the holder along with `r` and `v`|