# OAppAuthSender

[Git Source](https://github.com/Ion-Protocol/nucleus-boring-vault/blob/cc0b494b83e17b9b169a73b96050d2810b690477/src/base/Roles/CrossChain/OAppAuth/OAppAuthSender.sol)

**Inherits:** OAppAuthCore

*Abstract contract implementing the OAppSender functionality for sending messages to a LayerZero endpoint.*

*This Auth version of OAppCore uses solmate's Auth instead of OZ's Ownable for compatibility purposes*

## State Variables

### SENDER\_VERSION

```solidity
uint64 internal constant SENDER_VERSION = 1;
```

## Functions

### oAppVersion

Retrieves the OApp version information.

*Providing 0 as the default for OAppReceiver version. Indicates that the OAppReceiver is not implemented. ie. this is a SEND only OApp.*

*If the OApp uses both OAppSender and OAppReceiver, then this needs to be override returning the correct versions*

```solidity
function oAppVersion() public view virtual returns (uint64 senderVersion, uint64 receiverVersion);
```

**Returns**

| Name              | Type     | Description                                   |
| ----------------- | -------- | --------------------------------------------- |
| `senderVersion`   | `uint64` | The version of the OAppSender.sol contract.   |
| `receiverVersion` | `uint64` | The version of the OAppReceiver.sol contract. |

### \_quote

*Internal function to interact with the LayerZero EndpointV2.quote() for fee calculation.*

```solidity
function _quote(
    uint32 _dstEid,
    bytes memory _message,
    bytes memory _options,
    bool _payInLzToken
)
    internal
    view
    virtual
    returns (MessagingFee memory fee);
```

**Parameters**

| Name            | Type     | Description                                          |
| --------------- | -------- | ---------------------------------------------------- |
| `_dstEid`       | `uint32` | The destination endpoint ID.                         |
| `_message`      | `bytes`  | The message payload.                                 |
| `_options`      | `bytes`  | Additional options for the message.                  |
| `_payInLzToken` | `bool`   | Flag indicating whether to pay the fee in LZ tokens. |

**Returns**

| Name  | Type           | Description                                                                                                                               |
| ----- | -------------- | ----------------------------------------------------------------------------------------------------------------------------------------- |
| `fee` | `MessagingFee` | The calculated MessagingFee for the message. - nativeFee: The native fee for the message. - lzTokenFee: The LZ token fee for the message. |

### \_lzSend

*Internal function to interact with the LayerZero EndpointV2.send() for sending a message.*

```solidity
function _lzSend(
    uint32 _dstEid,
    bytes memory _message,
    bytes memory _options,
    MessagingFee memory _fee,
    address _refundAddress
)
    internal
    virtual
    returns (MessagingReceipt memory receipt);
```

**Parameters**

| Name             | Type           | Description                                                                                               |
| ---------------- | -------------- | --------------------------------------------------------------------------------------------------------- |
| `_dstEid`        | `uint32`       | The destination endpoint ID.                                                                              |
| `_message`       | `bytes`        | The message payload.                                                                                      |
| `_options`       | `bytes`        | Additional options for the message.                                                                       |
| `_fee`           | `MessagingFee` | The calculated LayerZero fee for the message. - nativeFee: The native fee. - lzTokenFee: The lzToken fee. |
| `_refundAddress` | `address`      | The address to receive any excess fee values sent to the endpoint.                                        |

**Returns**

| Name      | Type               | Description                                                                                                                                                                      |
| --------- | ------------------ | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| `receipt` | `MessagingReceipt` | The receipt for the sent message. - guid: The unique identifier for the sent message. - nonce: The nonce of the sent message. - fee: The LayerZero fee incurred for the message. |

### \_payNative

*Internal function to pay the native fee associated with the message.*

*If the OApp needs to initiate MULTIPLE LayerZero messages in a single transaction, this will need to be overridden because msg.value would contain multiple lzFees.*

*Should be overridden in the event the LayerZero endpoint requires a different native currency.*

*Some EVMs use an ERC20 as a method for paying transactions/gasFees.*

*The endpoint is EITHER/OR, ie. it will NOT support both types of native payment at a time.*

```solidity
function _payNative(uint256 _nativeFee) internal virtual returns (uint256 nativeFee);
```

**Parameters**

| Name         | Type      | Description                |
| ------------ | --------- | -------------------------- |
| `_nativeFee` | `uint256` | The native fee to be paid. |

**Returns**

| Name        | Type      | Description                         |
| ----------- | --------- | ----------------------------------- |
| `nativeFee` | `uint256` | The amount of native currency paid. |

### \_payLzToken

*Internal function to pay the LZ token fee associated with the message.*

*If the caller is trying to pay in the specified lzToken, then the lzTokenFee is passed to the endpoint.*

*Any excess sent, is passed back to the specified \_refundAddress in the \_lzSend().*

```solidity
function _payLzToken(uint256 _lzTokenFee) internal virtual;
```

**Parameters**

| Name          | Type      | Description                  |
| ------------- | --------- | ---------------------------- |
| `_lzTokenFee` | `uint256` | The LZ token fee to be paid. |

## Errors

### NotEnoughNative

```solidity
error NotEnoughNative(uint256 msgValue);
```

### LzTokenUnavailable

```solidity
error LzTokenUnavailable();
```