Axelar Network contest - IllIllI's results

Low Risk Issues

Cross-chain replay attacks

Storing the block.chainid is not safe. See this issue from a prior contest for details.

1. File: src/ERC20Permit.sol (lines 23-28)

        DOMAIN_SEPARATOR = keccak256(
            abi.encode(
                DOMAIN_TYPE_SIGNATURE_HASH,
                keccak256(bytes(name)),
                keccak256(bytes('1')),
                block.chainid,

Incorrect EIP-2612 deadline check

allow transferFrom to occur while expiry >= block.timestamp.

https://github.com/ethereum/EIPs/blob/1473025f064929bfab405eb00b8cd16dd741f269/EIPS/eip-2612.md?plain=1#L172 The current code should change to use <=

1. File: src/ERC20Permit.sol (line 43)

        require(block.timestamp < deadline, 'EXPIRED');

Unumplemented functions should have the default behavior of revert()ing rather than allowing operations to go through

1. File: src/interfaces/IAxelarExecutable.sol (lines 55-67)

    function _execute(
        string memory sourceChain,
        string memory sourceAddress,
        bytes calldata payload
    ) internal virtual {}

    function _executeWithToken(
        string memory sourceChain,
        string memory sourceAddress,
        bytes calldata payload,
        string memory tokenSymbol,
        uint256 amount
    ) internal virtual {}

Missing checks for address(0x0) when assigning values to address state variables

1. File: src/AxelarGateway.sol (line 67)

        TOKEN_DEPLOYER_IMPLEMENTATION = tokenDeployerImplementation;

Open TODOs

Code architecture, incentives, and error handling/reporting questions/issues should be resolved before deployment

1. File: src/MintableCappedERC20.sol (line 30)

    // TODO move burnFrom into a separate BurnableERC20 contract

Missing contract-existence checks before low-level calls

Low-level calls return success if there is no code present at the specified address. In addition to the zero-address checks, add a check to verify that <address>.code.length > 0

1. File: src/AxelarGateway.sol (lines 398-415)

        if (tokenAddress == address(0)) revert TokenDoesNotExist(symbol);

        if (_getTokenType(symbol) == TokenType.External) {
            _checkTokenStatus(symbol);

            DepositHandler depositHandler = new DepositHandler{ salt: salt }();

            (bool success, bytes memory returnData) = depositHandler.execute(
                tokenAddress,
                abi.encodeWithSelector(
                    IERC20.transfer.selector,
                    address(this),
                    IERC20(tokenAddress).balanceOf(address(depositHandler))
                )
            );

            if (!success || (returnData.length != uint256(0) && !abi.decode(returnData, (bool))))
                revert BurnFailed(symbol);

2. File: src/AxelarGatewayProxy.sol (line 19)

        (bool success, ) = gatewayImplementation.delegatecall(

3. File: src/AxelarGatewayProxy.sol (line 34)

            let result := delegatecall(gas(), implementation, 0, calldatasize(), 0, 0)

4. File: src/AxelarGateway.sol (line 350)

            (bool success, bytes memory data) = TOKEN_DEPLOYER_IMPLEMENTATION.delegatecall(

Non-critical Issues

require()/revert() statements should have descriptive reason strings

1. File: src/DepositHandler.sol (line 12)

        require(_lockedStatus == IS_NOT_LOCKED);

public functions not called by the contract should be declared external instead

Contracts are allowed to override their parents' functions and change the visibility from external to public.

1. File: src/BurnableMintableCappedERC20.sol (line 48)

    function burn(bytes32 salt) public onlyOwner {

2. File: src/MintableCappedERC20.sol (line 23)

    function mint(address account, uint256 amount) public onlyOwner {

constants should be defined rather than using magic numbers

1. File: src/BurnableMintableCappedERC20.sol (line 37)

                                bytes1(0xff),

2. File: src/ECDSA.sol (line 33)

        if (signature.length != 65) revert InvalidSignatureLength();

3. File: src/ECDSA.sol (line 58)

        if (uint256(s) > 0x7FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF5D576E7357A4501DDFE92F46681B20A0) revert InvalidS();

4. File: src/ECDSA.sol (line 60)

        if (v != 27 && v != 28) revert InvalidV();

5. File: src/ECDSA.sol (line 60)

        if (v != 27 && v != 28) revert InvalidV();

6. File: src/ERC20Permit.sol (line 44)

        require(uint256(s) <= 0x7FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF5D576E7357A4501DDFE92F46681B20A0, 'INV_S');

7. File: src/ERC20Permit.sol (line 45)

        require(v == 27 || v == 28, 'INV_V');

8. File: src/ERC20Permit.sol (line 45)

        require(v == 27 || v == 28, 'INV_V');

Use a more recent version of solidity

Use a solidity version of at least 0.8.12 to get string.concat() to be used instead of abi.encodePacked(<str>,<str>)

1. File: src/AxelarGateway.sol (line 3)

pragma solidity 0.8.9;

2. File: src/AdminMultisigBase.sol (line 3)

pragma solidity 0.8.9;

3. File: src/AxelarGatewayMultisig.sol (line 3)

pragma solidity 0.8.9;

4. File: src/BurnableMintableCappedERC20.sol (line 3)

pragma solidity 0.8.9;

5. File: src/ECDSA.sol (line 3)

pragma solidity 0.8.9;

6. File: src/ERC20Permit.sol (line 3)

pragma solidity 0.8.9;

Multiple address mappings can be combined into a single mapping of an address to a struct, where appropriate

1. File: src/ERC20.sol (lines 34-36)

    mapping(address => uint256) public override balanceOf;

    mapping(address => mapping(address => uint256)) public override allowance;

Variable names that consist of all capital letters should be reserved for const/immutable variables

If the variable needs to be different based on which class it comes from, a view/pure function should be used instead (e.g. like this).

1. File: src/ERC20Permit.sol (line 8)

    bytes32 public DOMAIN_SEPARATOR;

File is missing NatSpec

1. File: src/AdminMultisigBase.sol (line 0)

// SPDX-License-Identifier: MIT

2. File: src/DepositHandler.sol (line 0)

// SPDX-License-Identifier: MIT

3. File: src/BurnableMintableCappedERC20.sol (line 0)

// SPDX-License-Identifier: MIT

4. File: src/Ownable.sol (line 0)

// SPDX-License-Identifier: MIT

5. File: src/TokenDeployer.sol (line 0)

// SPDX-License-Identifier: MIT

6. File: src/interfaces/IAxelarGateway.sol (line 0)

// SPDX-License-Identifier: MIT

7. File: src/interfaces/IAxelarGatewayMultisig.sol (line 0)

// SPDX-License-Identifier: MIT

8. File: src/interfaces/IERC20BurnFrom.sol (line 0)

// SPDX-License-Identifier: MIT

9. File: src/interfaces/IAxelarExecutable.sol (line 0)

// SPDX-License-Identifier: MIT

10. File: src/MintableCappedERC20.sol (line 0)

// SPDX-License-Identifier: MIT

11. File: src/ERC20Permit.sol (line 0)

// SPDX-License-Identifier: MIT

Event is missing indexed fields

Each event should use three indexed fields if there are three or more fields

1. File: src/interfaces/IAxelarGateway.sol (lines 10-16)

    event TokenSent(
        address indexed sender,
        string destinationChain,
        string destinationAddress,
        string symbol,
        uint256 amount
    );

2. File: src/interfaces/IAxelarGateway.sol (lines 18-24)

    event ContractCall(
        address indexed sender,
        string destinationChain,
        string destinationContractAddress,
        bytes32 indexed payloadHash,
        bytes payload
    );

3. File: src/interfaces/IAxelarGateway.sol (lines 26-34)

    event ContractCallWithToken(
        address indexed sender,
        string destinationChain,
        string destinationContractAddress,
        bytes32 indexed payloadHash,
        bytes payload,
        string symbol,
        uint256 amount
    );

4. File: src/interfaces/IAxelarGateway.sol (line 38)

    event TokenDeployed(string symbol, address tokenAddresses);

5. File: src/interfaces/IAxelarGateway.sol (line 62)

    event TokenFrozen(string symbol);

6. File: src/interfaces/IAxelarGateway.sol (line 64)

    event TokenUnfrozen(string symbol);

7. File: src/interfaces/IAxelarGatewayMultisig.sol (line 8)

    event OwnershipTransferred(address[] preOwners, uint256 prevThreshold, address[] newOwners, uint256 newThreshold);

8. File: src/interfaces/IAxelarGatewayMultisig.sol (lines 10-15)

    event OperatorshipTransferred(
        address[] preOperators,
        uint256 prevThreshold,
        address[] newOperators,
        uint256 newThreshold
    );

9. File: src/interfaces/IERC20.sol (line 74)

    event Transfer(address indexed from, address indexed to, uint256 value);

10. File: src/interfaces/IERC20.sol (line 80)

    event Approval(address indexed owner, address indexed spender, uint256 value);

Unsafe early return from a modifier

If the modifier is used with a function that has a named return, the default value will be returned which may lead to confusing behavior. Consider using a function instead of a modifier

1. File: src/AdminMultisigBase.sol (lines 42-44)

        if (adminVoteCount < _getAdminThreshold(adminEpoch)) return;

        _;

Consider allowing infinite approval

Doing what OpenZeppelin does and considering type(uint256).max to be infinite approval may help users to create smaller transactions.

1. File: src/ERC20.sol (line 105)

        _approve(sender, _msgSender(), allowance[sender][_msgSender()] - amount);

Consider using a two-step-transfer of ownership

The current owner would nominate a new owner, and to become the new owner, the nominated account would have to approve the change, so that the address is proven to be valid

1. File: src/Ownable.sol (line 20)

    function transferOwnership(address newOwner) public virtual onlyOwner {

Consider adding a comment saying that EIP-2098 short signatures are not supported

1. File: src/ECDSA.sol (line 33)

        if (signature.length != 65) revert InvalidSignatureLength();

Using 1 and 2 rather than 0 and 1 saves gas

See this issue from a prior contest for details

1. File: src/DepositHandler.sol (lines 6-7)

    uint256 internal constant IS_NOT_LOCKED = uint256(0);
    uint256 internal constant IS_LOCKED = uint256(1);

Not using the named return variables when a function returns, wastes deployment gas

1. File: src/Context.sol (line 17)

        return payable(msg.sender);

Use a more recent version of solidity

Use a solidity version of at least 0.8.10 to have external calls skip contract existence checks if the external call has a return value

1. File: src/AxelarGateway.sol (line 3)

pragma solidity 0.8.9;

2. File: src/ERC20.sol (line 3)

pragma solidity 0.8.9;

3. File: src/AdminMultisigBase.sol (line 3)

pragma solidity 0.8.9;

4. File: src/Context.sol (line 3)

pragma solidity 0.8.9;

5. File: src/DepositHandler.sol (line 3)

pragma solidity 0.8.9;

6. File: src/AxelarGatewayMultisig.sol (line 3)

pragma solidity 0.8.9;

7. File: src/BurnableMintableCappedERC20.sol (line 3)

pragma solidity 0.8.9;

8. File: src/Ownable.sol (line 3)

pragma solidity 0.8.9;

9. File: src/EternalStorage.sol (line 3)

pragma solidity 0.8.9;

10. File: src/TokenDeployer.sol (line 3)

pragma solidity 0.8.9;

11. File: src/ECDSA.sol (line 3)

pragma solidity 0.8.9;

12. File: src/interfaces/IAxelarGateway.sol (line 3)

pragma solidity 0.8.9;

13. File: src/interfaces/IAxelarGatewayMultisig.sol (line 3)

pragma solidity 0.8.9;

14. File: src/interfaces/IERC20BurnFrom.sol (line 3)

pragma solidity 0.8.9;

15. File: src/interfaces/IAxelarExecutable.sol (line 3)

pragma solidity 0.8.9;

16. File: src/interfaces/IERC20.sol (line 3)

pragma solidity 0.8.9;

17. File: src/AxelarGatewayProxy.sol (line 3)

pragma solidity 0.8.9;

18. File: src/MintableCappedERC20.sol (line 3)

pragma solidity 0.8.9;

19. File: src/ERC20Permit.sol (line 3)

pragma solidity 0.8.9;

Using bools for storage incurs overhead

    // Booleans are more expensive than uint256 or any type that takes up a full
    // word because each write operation emits an extra SLOAD to first read the
    // slot's contents, replace the bits taken up by the boolean, and then write
    // back. This is the compiler's defense against contract upgrades and
    // pointer aliasing, and it cannot be disabled.

https://github.com/OpenZeppelin/openzeppelin-contracts/blob/58f635312aa21f947cae5f8578638a85aa2519f5/contracts/security/ReentrancyGuard.sol#L23-L27

1. File: src/EternalStorage.sol (line 14)

    mapping(bytes32 => bool) private _boolStorage;

<array>.length should not be looked up in every loop of a for-loop

Even memory arrays incur the overhead of bit tests and bit shifts to calculate the array length

1. File: src/AxelarGatewayMultisig.sol (line 118)

        for (uint256 i; i < accounts.length; i++) {

2. File: src/AxelarGatewayMultisig.sol (line 271)

        for (uint256 i; i < accounts.length; i++) {

Using calldata instead of memory for read-only arguments in external functions saves gas

1. File: src/AxelarGateway.sol (line 81)

        string memory destinationChain,

2. File: src/AxelarGateway.sol (line 82)

        string memory destinationAddress,

3. File: src/AxelarGateway.sol (line 83)

        string memory symbol,

4. File: src/AxelarGateway.sol (line 91)

        string memory destinationChain,

5. File: src/AxelarGateway.sol (line 92)

        string memory destinationContractAddress,

6. File: src/AxelarGateway.sol (line 93)

        bytes memory payload

7. File: src/AxelarGateway.sol (line 99)

        string memory destinationChain,

8. File: src/AxelarGateway.sol (line 100)

        string memory destinationContractAddress,

9. File: src/AxelarGateway.sol (line 101)

        bytes memory payload,

10. File: src/AxelarGateway.sol (line 102)

        string memory symbol,

11. File: src/AxelarGateway.sol (line 119)

        string memory sourceChain,

12. File: src/AxelarGateway.sol (line 120)

        string memory sourceAddress,

13. File: src/AxelarGateway.sol (line 130)

        string memory sourceChain,

14. File: src/AxelarGateway.sol (line 131)

        string memory sourceAddress,

15. File: src/AxelarGateway.sol (line 134)

        string memory symbol,

16. File: src/AxelarGateway.sol (line 153)

        string memory sourceChain,

17. File: src/AxelarGateway.sol (line 154)

        string memory sourceAddress,

18. File: src/AxelarGateway.sol (line 164)

        string memory sourceChain,

19. File: src/AxelarGateway.sol (line 165)

        string memory sourceAddress,

20. File: src/AxelarGateway.sol (line 167)

        string memory symbol,

21. File: src/AxelarGateway.sol (line 234)

    function freezeToken(string memory symbol) external override onlyAdmin {

22. File: src/AxelarGateway.sol (line 240)

    function unfreezeToken(string memory symbol) external override onlyAdmin {

23. File: src/TokenDeployer.sol (line 9)

        string memory name,

24. File: src/TokenDeployer.sol (line 10)

        string memory symbol,

25. File: src/interfaces/IAxelarGateway.sol (line 81)

        string memory destinationChain,

26. File: src/interfaces/IAxelarGateway.sol (line 82)

        string memory destinationAddress,

27. File: src/interfaces/IAxelarGateway.sol (line 83)

        string memory symbol,

28. File: src/interfaces/IAxelarGateway.sol (line 88)

        string memory destinationChain,

29. File: src/interfaces/IAxelarGateway.sol (line 89)

        string memory contractAddress,

30. File: src/interfaces/IAxelarGateway.sol (line 90)

        bytes memory payload

31. File: src/interfaces/IAxelarGateway.sol (line 94)

        string memory destinationChain,

32. File: src/interfaces/IAxelarGateway.sol (line 95)

        string memory contractAddress,

33. File: src/interfaces/IAxelarGateway.sol (line 96)

        bytes memory payload,

34. File: src/interfaces/IAxelarGateway.sol (line 97)

        string memory symbol,

35. File: src/interfaces/IAxelarGateway.sol (line 103)

        string memory sourceChain,

36. File: src/interfaces/IAxelarGateway.sol (line 104)

        string memory sourceAddress,

37. File: src/interfaces/IAxelarGateway.sol (line 111)

        string memory sourceChain,

38. File: src/interfaces/IAxelarGateway.sol (line 112)

        string memory sourceAddress,

39. File: src/interfaces/IAxelarGateway.sol (line 115)

        string memory symbol,

40. File: src/interfaces/IAxelarGateway.sol (line 121)

        string memory sourceChain,

41. File: src/interfaces/IAxelarGateway.sol (line 122)

        string memory sourceAddress,

42. File: src/interfaces/IAxelarGateway.sol (line 128)

        string memory sourceChain,

43. File: src/interfaces/IAxelarGateway.sol (line 129)

        string memory sourceAddress,

44. File: src/interfaces/IAxelarGateway.sol (line 131)

        string memory symbol,

45. File: src/interfaces/IAxelarGateway.sol (line 143)

    function tokenAddresses(string memory symbol) external view returns (address);

46. File: src/interfaces/IAxelarGateway.sol (line 145)

    function tokenFrozen(string memory symbol) external view returns (bool);

47. File: src/interfaces/IAxelarGateway.sol (line 159)

    function freezeToken(string memory symbol) external;

48. File: src/interfaces/IAxelarGateway.sol (line 161)

    function unfreezeToken(string memory symbol) external;

49. File: src/interfaces/IAxelarExecutable.sol (line 18)

        string memory sourceChain,

50. File: src/interfaces/IAxelarExecutable.sol (line 19)

        string memory sourceAddress,

51. File: src/interfaces/IAxelarExecutable.sol (line 30)

        string memory sourceChain,

52. File: src/interfaces/IAxelarExecutable.sol (line 31)

        string memory sourceAddress,

53. File: src/interfaces/IAxelarExecutable.sol (line 33)

        string memory tokenSymbol,

++i/i++ should be unchecked{++i}/unchecked{++i} when it is not possible for them to overflow, as is the case when used in for- and while-loops

1. File: src/AxelarGateway.sol (line 225)

        for (uint256 i; i < adminCount; i++) {

2. File: src/AdminMultisigBase.sol (line 51)

        for (uint256 i; i < adminCount; i++) {

3. File: src/AdminMultisigBase.sol (line 158)

        for (uint256 i; i < adminLength; i++) {

4. File: src/AxelarGatewayMultisig.sol (line 42)

        for (uint256 i; i < accounts.length - 1; ++i) {

5. File: src/AxelarGatewayMultisig.sol (line 118)

        for (uint256 i; i < accounts.length; i++) {

6. File: src/AxelarGatewayMultisig.sol (line 140)

        for (uint256 i; i < ownerCount; i++) {

7. File: src/AxelarGatewayMultisig.sol (line 181)

        for (uint256 i; i < accountLength; i++) {

8. File: src/AxelarGatewayMultisig.sol (line 271)

        for (uint256 i; i < accounts.length; i++) {

9. File: src/AxelarGatewayMultisig.sol (line 293)

        for (uint256 i; i < operatorCount; i++) {

10. File: src/AxelarGatewayMultisig.sol (line 332)

        for (uint256 i; i < accountLength; i++) {

11. File: src/AxelarGatewayMultisig.sol (line 495)

        for (uint256 i; i < signatureCount; i++) {

12. File: src/AxelarGatewayMultisig.sol (line 526)

        for (uint256 i; i < commandsLength; i++) {

++i costs less gas than ++i, especially when it's used in for-loops (--i/i-- too)

1. File: src/AxelarGateway.sol (line 225)

        for (uint256 i; i < adminCount; i++) {

2. File: src/AdminMultisigBase.sol (line 51)

        for (uint256 i; i < adminCount; i++) {

3. File: src/AdminMultisigBase.sol (line 158)

        for (uint256 i; i < adminLength; i++) {

4. File: src/AxelarGatewayMultisig.sol (line 118)

        for (uint256 i; i < accounts.length; i++) {

5. File: src/AxelarGatewayMultisig.sol (line 140)

        for (uint256 i; i < ownerCount; i++) {

6. File: src/AxelarGatewayMultisig.sol (line 181)

        for (uint256 i; i < accountLength; i++) {

7. File: src/AxelarGatewayMultisig.sol (line 271)

        for (uint256 i; i < accounts.length; i++) {

8. File: src/AxelarGatewayMultisig.sol (line 293)

        for (uint256 i; i < operatorCount; i++) {

9. File: src/AxelarGatewayMultisig.sol (line 332)

        for (uint256 i; i < accountLength; i++) {

10. File: src/AxelarGatewayMultisig.sol (line 495)

        for (uint256 i; i < signatureCount; i++) {

11. File: src/AxelarGatewayMultisig.sol (line 526)

        for (uint256 i; i < commandsLength; i++) {

Usage of uints/ints smaller than 32 bytes (256 bits) incurs overhead

When using elements that are smaller than 32 bytes, your contract’s gas usage may be higher. This is because the EVM operates on 32 bytes at a time. Therefore, if the element is smaller than that, the EVM must use more operations in order to reduce the size of the element from 32 bytes to the desired size.

https://docs.soliditylang.org/en/v0.8.11/internals/layout_in_storage.html Use a larger size then downcast where needed

1. File: src/AxelarGateway.sol (line 62)

    uint8 internal constant OLD_KEY_RETENTION = 16;

2. File: src/AxelarGateway.sol (line 339)

        uint8 decimals,

3. File: src/ERC20.sol (line 43)

    uint8 public immutable decimals;

4. File: src/ERC20.sol (line 54)

        uint8 decimals_

5. File: src/AxelarGatewayMultisig.sol (line 363)

        (string memory name, string memory symbol, uint8 decimals, uint256 cap, address tokenAddr) = abi.decode(

6. File: src/BurnableMintableCappedERC20.sol (line 24)

        uint8 decimals,

7. File: src/TokenDeployer.sol (line 11)

        uint8 decimals,

8. File: src/ECDSA.sol (line 38)

        uint8 v;

9. File: src/MintableCappedERC20.sol (line 17)

        uint8 decimals,

10. File: src/ERC20Permit.sol (line 39)

        uint8 v,

Expressions for constant values such as a call to keccak256(), should use immutable rather than constant

See this issue for a detail description of the issue

1. File: src/AxelarGateway.sol (line 45)

    bytes32 internal constant KEY_ALL_TOKENS_FROZEN = keccak256('all-tokens-frozen');

2. File: src/AxelarGateway.sol (line 47)

    bytes32 internal constant PREFIX_COMMAND_EXECUTED = keccak256('command-executed');

3. File: src/AxelarGateway.sol (line 48)

    bytes32 internal constant PREFIX_TOKEN_ADDRESS = keccak256('token-address');

4. File: src/AxelarGateway.sol (line 49)

    bytes32 internal constant PREFIX_TOKEN_TYPE = keccak256('token-type');

5. File: src/AxelarGateway.sol (line 50)

    bytes32 internal constant PREFIX_TOKEN_FROZEN = keccak256('token-frozen');

6. File: src/AxelarGateway.sol (line 51)

    bytes32 internal constant PREFIX_CONTRACT_CALL_APPROVED = keccak256('contract-call-approved');

7. File: src/AxelarGateway.sol (line 52)

    bytes32 internal constant PREFIX_CONTRACT_CALL_APPROVED_WITH_MINT = keccak256('contract-call-approved-with-mint');

8. File: src/AxelarGateway.sol (line 54)

    bytes32 internal constant SELECTOR_BURN_TOKEN = keccak256('burnToken');

9. File: src/AxelarGateway.sol (line 55)

    bytes32 internal constant SELECTOR_DEPLOY_TOKEN = keccak256('deployToken');

10. File: src/AxelarGateway.sol (line 56)

    bytes32 internal constant SELECTOR_MINT_TOKEN = keccak256('mintToken');

11. File: src/AxelarGateway.sol (line 57)

    bytes32 internal constant SELECTOR_APPROVE_CONTRACT_CALL = keccak256('approveContractCall');

12. File: src/AxelarGateway.sol (line 58)

    bytes32 internal constant SELECTOR_APPROVE_CONTRACT_CALL_WITH_MINT = keccak256('approveContractCallWithMint');

13. File: src/AxelarGateway.sol (line 59)

    bytes32 internal constant SELECTOR_TRANSFER_OPERATORSHIP = keccak256('transferOperatorship');

14. File: src/AxelarGateway.sol (line 60)

    bytes32 internal constant SELECTOR_TRANSFER_OWNERSHIP = keccak256('transferOwnership');

15. File: src/AdminMultisigBase.sol (line 16)

    bytes32 internal constant KEY_ADMIN_EPOCH = keccak256('admin-epoch');

16. File: src/AdminMultisigBase.sol (line 18)

    bytes32 internal constant PREFIX_ADMIN = keccak256('admin');

17. File: src/AdminMultisigBase.sol (line 19)

    bytes32 internal constant PREFIX_ADMIN_COUNT = keccak256('admin-count');

18. File: src/AdminMultisigBase.sol (line 20)

    bytes32 internal constant PREFIX_ADMIN_THRESHOLD = keccak256('admin-threshold');

19. File: src/AdminMultisigBase.sol (line 21)

    bytes32 internal constant PREFIX_ADMIN_VOTE_COUNTS = keccak256('admin-vote-counts');

20. File: src/AdminMultisigBase.sol (line 22)

    bytes32 internal constant PREFIX_ADMIN_VOTED = keccak256('admin-voted');

21. File: src/AdminMultisigBase.sol (line 23)

    bytes32 internal constant PREFIX_IS_ADMIN = keccak256('is-admin');

22. File: src/AxelarGatewayMultisig.sol (line 25)

    bytes32 internal constant KEY_OWNER_EPOCH = keccak256('owner-epoch');

23. File: src/AxelarGatewayMultisig.sol (line 27)

    bytes32 internal constant PREFIX_OWNER = keccak256('owner');

24. File: src/AxelarGatewayMultisig.sol (line 28)

    bytes32 internal constant PREFIX_OWNER_COUNT = keccak256('owner-count');

25. File: src/AxelarGatewayMultisig.sol (line 29)

    bytes32 internal constant PREFIX_OWNER_THRESHOLD = keccak256('owner-threshold');

26. File: src/AxelarGatewayMultisig.sol (line 30)

    bytes32 internal constant PREFIX_IS_OWNER = keccak256('is-owner');

27. File: src/AxelarGatewayMultisig.sol (line 32)

    bytes32 internal constant KEY_OPERATOR_EPOCH = keccak256('operator-epoch');

28. File: src/AxelarGatewayMultisig.sol (line 34)

    bytes32 internal constant PREFIX_OPERATOR = keccak256('operator');

29. File: src/AxelarGatewayMultisig.sol (line 35)

    bytes32 internal constant PREFIX_OPERATOR_COUNT = keccak256('operator-count');

30. File: src/AxelarGatewayMultisig.sol (line 36)

    bytes32 internal constant PREFIX_OPERATOR_THRESHOLD = keccak256('operator-threshold');

31. File: src/AxelarGatewayMultisig.sol (line 37)

    bytes32 internal constant PREFIX_IS_OPERATOR = keccak256('is-operator');

Duplicated require()/revert() checks should be refactored to a modifier or function

1. File: src/ERC20.sol (line 205)

        require(account != address(0), 'ZERO_ADDR');

State variables only set in the constructor should be declared immutable

1. File: src/ERC20.sol (line 40)

    string public name;

2. File: src/ERC20.sol (line 41)

    string public symbol;

3. File: src/MintableCappedERC20.sol (line 12)

    uint256 public cap;

Use custom errors rather than revert()/require() strings to save deployment gas

1. File: src/ERC20.sol (Various lines throughout the file)
2. File: src/DepositHandler.sol (Various lines throughout the file)
3. File: src/BurnableMintableCappedERC20.sol (Various lines throughout the file)
4. File: src/Ownable.sol (Various lines throughout the file)
5. File: src/AxelarGatewayProxy.sol (Various lines throughout the file)
6. File: src/MintableCappedERC20.sol (Various lines throughout the file)
7. File: src/ERC20Permit.sol (Various lines throughout the file)

Functions guaranteed to revert when called by normal users can be marked payable

If a function modifier such as onlyOwner is used, the function will revert if a normal user tries to pay the function. Marking the function as payable will lower the gas cost for legitimate callers because the compiler will not include checks for whether a payment was provided.

1. File: src/AxelarGateway.sol (line 234)

    function freezeToken(string memory symbol) external override onlyAdmin {

2. File: src/AxelarGateway.sol (line 240)

    function unfreezeToken(string memory symbol) external override onlyAdmin {

3. File: src/AxelarGateway.sol (line 246)

    function freezeAllTokens() external override onlyAdmin {

4. File: src/AxelarGateway.sol (line 252)

    function unfreezeAllTokens() external override onlyAdmin {

5. File: src/AxelarGateway.sol (lines 258-262)

    function upgrade(
        address newImplementation,
        bytes32 newImplementationCodeHash,
        bytes calldata setupParams
    ) external override onlyAdmin {

6. File: src/AxelarGatewayMultisig.sol (line 362)

    function deployToken(bytes calldata params, bytes32) external onlySelf {

7. File: src/AxelarGatewayMultisig.sol (line 371)

    function mintToken(bytes calldata params, bytes32) external onlySelf {

8. File: src/AxelarGatewayMultisig.sol (line 377)

    function burnToken(bytes calldata params, bytes32) external onlySelf {

9. File: src/AxelarGatewayMultisig.sol (line 383)

    function approveContractCall(bytes calldata params, bytes32 commandId) external onlySelf {

10. File: src/AxelarGatewayMultisig.sol (line 404)

    function approveContractCallWithMint(bytes calldata params, bytes32 commandId) external onlySelf {

11. File: src/AxelarGatewayMultisig.sol (line 429)

    function transferOwnership(bytes calldata params, bytes32) external onlySelf {

12. File: src/AxelarGatewayMultisig.sol (line 440)

    function transferOperatorship(bytes calldata params, bytes32) external onlySelf {

13. File: src/BurnableMintableCappedERC20.sol (line 48)

    function burn(bytes32 salt) public onlyOwner {

14. File: src/Ownable.sol (line 20)

    function transferOwnership(address newOwner) public virtual onlyOwner {

15. File: src/MintableCappedERC20.sol (line 23)

    function mint(address account, uint256 amount) public onlyOwner {

16. File: src/MintableCappedERC20.sol (line 31)

    function burnFrom(address account, uint256 amount) external onlyOwner {