eth_broker_contract.md

BZZ Smart Contract Ecosystem

ETH Broker Contract

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Index

ETH Broker Contract

• Inheritance
• Implementation
  • Views
    • buyPrice
    • sellReward
    • sellRewardDai
    • getPath
    • getTime
  • State Modifying
    • mint
    • burn
    • Fallback Function

Additional documentation

< README

~ ETH Broker Contract

> Audit Report and Info

> Admin Permissions and Risks

> Token Contract

> Curve Contract

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ETH Broker Contract

The ETH broker contract enables users to be able to mint and burn BZZ Tokens with ETH rather than the collateral currency (DAI).

Implementation

Below is a function by function breakdown of the curve contract.

Views

buyPrice

Purpose: The buyPrice function allows a user to check how much it will cost them in ETH to buy the desired amount of the bonded token (BZZ).

Parameters:

• The _amount of bonded tokens the user would like to buy.

Returns:

• The ETH cost for buying the token amount.

Possible Exceptions:

• N/A

sellReward

Purpose: The sellReward function allows the user to check how much ETH they will get for selling the specified amount of bonded tokens (BZZ).

Parameters:

• The _amount of bonded tokens the user would like to sell.

Returns:

• The ETH reward for selling the specified amount of bonded tokens.

Possible Exceptions:

• N/A

sellRewardDai

Purpose: Allows a user to see the current conversion rate between the collateral token of the curve (DAI) and ETH.

Parameters:

• The _daiAmount.

Returns:

• The ETH amount the user can get for selling the specified DAI amount.

Possible Exceptions:

• N/A

getPath

Purpose: Gets the trading path needed by Uniswap to trade between DAI and ETH.

Parameters:

• A bool switch for if it is a buy path.

Returns:

• If the bool is true then the path will return the WETH address followed by the DAI address, if false it will return the DAI address first, WETH second.

Possible Exceptions:

• N/A

getTime

Purpose: To return the current time stamp held on the blockchain.

Parameters:

• N/A

Returns:

• The current Unix time stamp.

Possible Exceptions:

• N/A

State Modifying

mint

Purpose: Allows a user to mint the curves bonded tokens (BZZ) with ETH.

Parameters:

• The _tokenAmount of bonded tokens the user would like to buy.
• The _maxDaiSpendAmount is the max amount of collateral tokens the user wants to spend in order to buy the desired amount of bonded tokens.
• The time stamp _deadline by which the transaction will expire and revert.

Returns:

• The success state of the mint. If true the mint executed successfully.

Events:

// Emitted when tokens are minted
    event mintTokensWithEth(
        address indexed buyer,      // The address of the buyer
        uint256 amount,             // The amount of bonded tokens to mint
        uint256 priceForTokensDai,  // The price in DAI for the token amount
        uint256 EthTradedForDai,    // The ETH amount sold for DAI
        uint256 maxSpendDai         // The max amount of DAI to spend
    );

Possible Exceptions:

• If the required DAI amount is higher than the users _maxDaiSpendAmount then the revert message will be "DAI required for trade above max".
• If the transferring of BZZ from the broker to the user fails the revert message will be "Transferring of bzz failed". Note that should this revert message be received there is a fatal flaw. This message should not be received.

burn

Purpose: Allows a user to burn their bonded tokens (BZZ) for ETH.

Parameters:

• The _tokenAmount of bonded tokens (BZZ) the user would like to buy.
• The _minDaiSellValue is the minimum amount of collateral token (DAI) the user is willing to receive for selling the specified amount of bonded tokens.
• The time stamp _deadline by which the transaction will expire and revert.

Returns:

• The success state of the burn. If true the burn executed successfully.

Events:

// Emitted when tokens are burnt
    event burnTokensWithEth(
        address indexed seller,     // The address of the seller
        uint256 amount,             // The amount of bonded tokens to burn
        uint256 rewardReceivedDai,  // The amount of DAI received for selling
        uint256 ethReceivedForDai,  // How much ETH the DAI was traded for
        uint256 minRewardDai        // The min amount of DAI to sell for
    );

Possible Exceptions:

• If the DAI reward for selling the bonded tokens is below the users _minDaiSellValue then the revert message will be "DAI required for trade below min".
• If the user has not approved the broker as a spender of their bonded tokens (BZZ) the revert message will be "Transferring BZZ failed".
• If the broker fails to burn the bonded tokens against the curve the revert message will be "Curve burn failed". Note that should this revert message be received there is a fatal flaw. This message should not be received.

Fallback Function

Purpose: Allows the Uniswap router to send ETH to the broker.

Parameters:

• N/A

Returns:

• N/A

Events:

• N/A

Possible Exceptions:

• If the msg.sender is not the router address the revert message will be "ETH not accepted outside router".