Add LinkToken on Avalanche [bridge v2]

CHANGELOG.md

@@ -9,6 +9,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 ### Added
 
 - Access controlled mintable & burnable LinkToken, for use on sidechains and L2 networks.
+- Documentation and token implementation for the Avalanche bridge v2.
 - Added versioning to v0.6 & v0.7 contracts
 
 ### Changed

contracts/v0.7/bridge/README.md

@@ -23,3 +23,5 @@ NOTICE: Current implementation of LinkTokenChild contract requires some addition
   gets defined, and once online transfer the ownership (bridge gateway role) to the new bridge.
 
 TODO: Potentially create an upgradeable `LinkTokenChild.sol` and limit gateway support to only one (owner)!
+
+- `./token/avalanche/`: Documentation and token implementation for the Avalanche bridge v2.

contracts/v0.7/bridge/token/avalanche/IERC20Avalanche.sol

@@ -0,0 +1,73 @@
+// SPDX-License-Identifier: MIT
+pragma solidity >0.6.0 <0.8.0;
+
+/* Interface Imports */
+import { IERC20 } from "../../../../../vendor/OpenZeppelin/openzeppelin-contracts/contracts/token/ERC20/IERC20.sol";
+
+/// @dev Interface for the bridged ERC20 token expected by the Avalanche standard bridge.
+interface IERC20Avalanche is IERC20 {
+
+  function mint(
+    address to,
+    uint256 amount,
+    address fee_address,
+    uint256 fee_amount,
+    bytes32 origin_tx_id
+  )
+    external;
+
+  function chain_ids(
+    uint256 id
+  )
+    external
+    view
+    returns (bool);
+
+  function add_supported_chain_id(
+    uint256 chain_id
+  )
+    external;
+
+  /**
+   * @dev Destroys `amount` tokens from `msg.sender. This function is monitored by the Avalanche bridge.
+   * @notice Call this when withdrawing tokens from Avalanche (NOT the direct `burn/burnFrom` method!).
+   * @param amount Number of tokens to unwrap.
+   * @param chain_id Id of the chain/network where to withdraw tokens.
+   */
+  function unwrap(
+    uint256 amount,
+    uint256 chain_id
+  )
+    external;
+
+  /**
+   * @dev Transfers bridge role from `msg.sender` to `new_bridge_role_address`.
+   * @param new_bridge_role_address Address of the new bridge operator.
+   */
+  function migrate_bridge_role(
+    address new_bridge_role_address
+  )
+    external;
+
+  function add_swap_token(
+    address contract_address,
+    uint256 supply_increment
+  )
+    external;
+
+  function remove_swap_token(
+    address contract_address,
+    uint256 supply_decrement
+  )
+    external;
+
+  /**
+   * @param token Address of the token to swap.
+   * @param amount Number of tokens to swap.
+   */
+  function swap(
+    address token,
+    uint256 amount
+  )
+    external;
+}

contracts/v0.7/bridge/token/avalanche/LinkTokenAvalanche.sol

@@ -0,0 +1,249 @@
+// SPDX-License-Identifier: MIT
+pragma solidity >0.6.0 <0.8.0;
+
+/* Interface Imports */
+import { ITypeAndVersion } from "../../../../v0.6/ITypeAndVersion.sol";
+import { IERC20Avalanche } from "./IERC20Avalanche.sol";
+
+/* Library Imports */
+import { Address } from "../../../../../vendor/OpenZeppelin/openzeppelin-contracts/contracts/utils/Address.sol";
+import { SafeMath } from "../../../../../vendor/OpenZeppelin/openzeppelin-contracts/contracts/math/SafeMath.sol";
+
+/* Contract Imports */
+import { Ownable } from "../../../../../vendor/OpenZeppelin/openzeppelin-contracts/contracts/access/Ownable.sol";
+import { ERC20 } from "../../../../../vendor/OpenZeppelin/openzeppelin-contracts/contracts/token/ERC20/ERC20.sol";
+import { ERC20Burnable } from "../../../../../vendor/OpenZeppelin/openzeppelin-contracts/contracts/token/ERC20/ERC20Burnable.sol";
+import { LinkToken } from "../../../../v0.6/LinkToken.sol";
+
+/// @dev Access controlled mintable & burnable LinkToken, for use on Avalanche network.
+contract LinkTokenAvalanche is ITypeAndVersion, IERC20Avalanche, ERC20Burnable, LinkToken, Ownable {
+  using SafeMath for uint256;
+
+  struct SwapToken {
+    address tokenContract;
+    uint256 supply;
+  }
+
+  mapping(address => SwapToken) s_swapTokens;
+  mapping(uint256 => bool) s_chainIds;
+
+  /**
+   * @notice versions:
+   *
+   * - LinkTokenAvalanche 0.0.1: initial release
+   *
+   * @inheritdoc ITypeAndVersion
+   */
+  function typeAndVersion()
+    external
+    pure
+    override(ITypeAndVersion, LinkToken)
+    virtual
+    returns (string memory)
+  {
+    return "LinkTokenAvalanche 0.0.1";
+  }
+
+  /// @inheritdoc IERC20Avalanche
+  function chain_ids(
+    uint256 id
+  )
+    public
+    view
+    override
+    returns (bool)
+  {
+    return s_chainIds[id];
+  }
+
+  /// @inheritdoc IERC20Avalanche
+  function mint(
+    address to,
+    uint256 amount,
+    address fee_address,
+    uint256 fee_amount,
+    bytes32 /* origin_tx_id */
+  )
+    public
+    override
+  {
+    require(owner() == _msgSender(), "DOES_NOT_HAVE_BRIDGE_ROLE");
+    _mint(to, amount);
+    if (fee_amount > 0) {
+      _mint(fee_address, fee_amount);
+    }
+  }
+
+  /// @inheritdoc IERC20Avalanche
+  function add_supported_chain_id(
+    uint256 chain_id
+  )
+    public
+    override
+  {
+    require(owner() == _msgSender(), "DOES_NOT_HAVE_BRIDGE_ROLE");
+    s_chainIds[chain_id] = true;
+  }
+
+  /// @inheritdoc IERC20Avalanche
+  function unwrap(
+    uint256 amount,
+    uint256 chain_id
+  )
+    public
+    override
+  {
+    require(s_chainIds[chain_id] == true, "CHAIN_ID_NOT_SUPPORTED");
+    _burn(_msgSender(), amount);
+  }
+
+  /// @inheritdoc IERC20Avalanche
+  function migrate_bridge_role(
+    address new_bridge_role_address
+  )
+    public
+    override
+  {
+    require(owner() == _msgSender(), "DOES_NOT_HAVE_BRIDGE_ROLE");
+    transferOwnership(new_bridge_role_address);
+  }
+
+  /// @inheritdoc IERC20Avalanche
+  function add_swap_token(
+    address contract_address,
+    uint256 supply_increment
+  )
+    public
+    override
+  {
+    require(owner() == _msgSender(), "DOES_NOT_HAVE_BRIDGE_ROLE");
+    require(Address.isContract(contract_address), "ADDRESS_IS_NOT_CONTRACT");
+
+    // If the swap token is not already supported, add it with the total supply of supply_increment
+    // Otherwise, increment the current supply.
+    if (s_swapTokens[contract_address].tokenContract == address(0)) {
+      s_swapTokens[contract_address] = SwapToken({
+          tokenContract: contract_address,
+          supply: supply_increment
+      });
+    } else {
+      s_swapTokens[contract_address].supply =
+        s_swapTokens[contract_address].supply.add(supply_increment);
+    }
+  }
+
+  /// @inheritdoc IERC20Avalanche
+  function remove_swap_token(
+    address contract_address,
+    uint256 supply_decrement
+  )
+    public
+    override
+  {
+    require(owner() == _msgSender(), "DOES_NOT_HAVE_BRIDGE_ROLE");
+    require(Address.isContract(contract_address), "ADDRESS_IS_NOT_CONTRACT");
+    require(s_swapTokens[contract_address].tokenContract != address(0), "SWAP_TOKEN_IS_NOT_SUPPORTED");
+
+    // If the decrement is less than the current supply, decrement it from the current supply.
+    // Otherwise, if the decrement is greater than or equal to the current supply, delete the mapping value.
+    if (s_swapTokens[contract_address].supply > supply_decrement) {
+      s_swapTokens[contract_address].supply =
+        s_swapTokens[contract_address].supply.sub(supply_decrement);
+    } else {
+      delete s_swapTokens[contract_address];
+    }
+  }
+
+  /// @inheritdoc IERC20Avalanche
+  function swap(
+    address token,
+    uint256 amount
+  )
+    public
+    override
+  {
+    require(Address.isContract(token), "TOKEN_IS_NOT_CONTRACT");
+    require(s_swapTokens[token].tokenContract != address(0), "SWAP_TOKEN_IS_NOT_SUPPORTED");
+    require(amount <= s_swapTokens[token].supply, "SWAP_AMOUNT_MORE_THAN_ALLOWED_SUPPLY");
+
+    // Update the allowed swap amount.
+    s_swapTokens[token].supply = s_swapTokens[token].supply.sub(amount);
+
+    // Burn the old token.
+    ERC20Burnable swapToken = ERC20Burnable(s_swapTokens[token].tokenContract);
+    swapToken.burnFrom(_msgSender(), amount);
+
+    // Mint the new token.
+    _mint(_msgSender(), amount);
+  }
+
+  /**
+   * @notice WARNING: Will burn tokens, without withdrawing them to the origin chain!
+   * To withdraw tokens use the `unwrap` method, which is monitored by the bridge
+   *
+   * @inheritdoc ERC20Burnable
+   */
+  function burn(
+    uint256 amount
+  )
+    public
+    override
+    virtual
+  {
+    super.burn(amount);
+  }
+
+  /**
+   * @notice WARNING: Will burn tokens, without withdrawing them to the origin chain!
+   * To withdraw tokens use the `unwrap` method, which is monitored by the bridge
+   *
+   * @inheritdoc ERC20Burnable
+   */
+  function burnFrom(
+    address account,
+    uint256 amount
+  )
+    public
+    override
+    virtual
+  {
+    super.burnFrom(account, amount);
+  }
+
+  /**
+   * @dev Overrides parent contract so no tokens are minted on deployment.
+   * @inheritdoc LinkToken
+   */
+  function _onCreate()
+    internal
+    override
+  {
+    s_chainIds[0] = true;
+  }
+
+  /// @inheritdoc LinkToken
+  function _transfer(
+    address sender,
+    address recipient,
+    uint256 amount
+  )
+    internal
+    override(ERC20, LinkToken)
+    virtual
+  {
+    super._transfer(sender, recipient, amount);
+  }
+
+  /// @inheritdoc LinkToken
+  function _approve(
+    address owner,
+    address spender,
+    uint256 amount
+  )
+    internal
+    override(ERC20, LinkToken)
+    virtual
+  {
+    super._approve(owner, spender, amount);
+  }
+}

contracts/v0.7/bridge/token/avalanche/README.md

@@ -0,0 +1,13 @@
+# LINK Token on Avalanche
+
+- `./token/IERC20Avalanche.sol`: Interface for the bridged ERC20 token expected by the Avalanche standard bridge.
+- `./token/LinkTokenAvalanche.sol`: Access controlled mintable & burnable LinkToken, for use on Avalanche network.
+
+`LinkTokenAvalanche.sol` is a slightly modified version of Avalanche's standard bridged ERC20 token and will be connected to the bridge operator once the bridge is online and operational. Modifications include:
+
+- Contract versioning via `ITypeAndVersion` interface
+- ERC677 support by extending the `LinkToken` contract
+- Transfers & approves to the contract itself blocked (provided by `LinkToken` contract)
+- Using OZ's `Ownable` contract to express the bridge operator role instead the original custom `Roles` contract
+
+The public bridge contracts source code and addresses are still TBA by the Avalanche team.