Bancor Process Quality Review

Score 96%

This is a Process Quality Review of Bancor completed on 3 November 2020. It was performed using the Process Review process (version 0.6) and is documented here. The review was performed by ShinkaRex of Caliburn Consulting. Check out our Telegram.

The final score of the review is 96%, an excellent score. The breakdown of the scoring is in Scoring Appendix.

Summary of the Process

Very simply, the review looks for the following declarations from the developer's site. With these declarations, it is reasonable to trust the smart contracts.

  • Here are my smart contracts on the blockchain

  • Here is the documentation that explains what my smart contracts do

  • Here are the tests I ran to verify my smart contract

  • Here are the audit(s) performed on my code by third party experts

Disclaimer

This report is for informational purposes only and does not constitute investment advice of any kind, nor does it constitute an offer to provide investment advisory or other services. Nothing in this report shall be considered a solicitation or offer to buy or sell any security, future, option or other financial instrument or to offer or provide any investment advice or service to any person in any jurisdiction. Nothing contained in this report constitutes investment advice or offers any opinion with respect to the suitability of any security, and the views expressed in this report should not be taken as advice to buy, sell or hold any security. The information in this report should not be relied upon for the purpose of investing. In preparing the information contained in this report, we have not taken into account the investment needs, objectives and financial circumstances of any particular investor. This information has no regard to the specific investment objectives, financial situation and particular needs of any specific recipient of this information and investments discussed may not be suitable for all investors.

Any views expressed in this report by us were prepared based upon the information available to us at the time such views were written. Changed or additional information could cause such views to change. All information is subject to possible correction. Information may quickly become unreliable for various reasons, including changes in market conditions or economic circumstances.

Code and Team

This section looks at the code deployed on the Mainnet that gets reviewed and its corresponding software repository. The document explaining these questions is here. This review will answer the questions;

  1. Are the executing code addresses readily available? (Y/N)

  2. Is the code actively being used? (%)

  3. Is there a public software repository? (Y/N)

  4. Is there a development history visible? (%)

  5. Is the team public (not anonymous)? (Y/N)

Are the executing code addresses readily available? (Y/N)

Answer: Yes

They are available at website https://docs.bancor.network/ethereum-contracts/addresses as indicated in the Appendix. This review only covers the contract ContractRegistry.sol.

How to improve this score

Make the Ethereum addresses of the smart contract utilized by your application available on either your website or your GitHub (in the README for instance). Ensure the addresses is up to date. This is a very important question wrt to the final score.

Is the code actively being used? (%)

Answer: 100%

Activity is well in excess of 10 transactions a day, as indicated in the Appendix. This uses 0x2F9EC37d6CcFFf1caB21733BdaDEdE11c823cCB0 (Bancor Network) token.

Percentage Score Guidance

100% More than 10 transactions a day 70% More than 10 transactions a week 40% More than 10 transactions a month 10% Less than 10 transactions a month 0% No activity

Is there a public software repository? (Y/N)

Answer: Yes

Location: https://github.com/bancorprotocol/

Is there a public software repository with the code at a minimum, but normally test and scripts also (Y/N). Even if the repo was created just to hold the files and has just 1 transaction, it gets a Yes. For teams with private repos, this answer is No.

Is there a development history visible? (%)

Answer: 100%

With 5 branches and 3640 commits, this is a healthy repository.

This checks if the software repository demonstrates a strong steady history. This is normally demonstrated by commits, branches and releases in a software repository. A healthy history demonstrates a history of more than a month (at a minimum).

Guidance: 100% Any one of 100+ commits, 10+branches 70% Any one of 70+ commits, 7+branches 50% Any one of 50+ commits, 5+branches 30% Any one of 30+ commits, 3+branches 0% Less than 2 branches or less than 10 commits

Is the team public (not anonymous)? (Y/N)

Answer: Yes

The names of the team members can be found in their Whitepaper.

For a yes in this question the real names of some team members must be public on the website or other documentation. If the team is anonymous and then this question seems a No.

Documentation

This section looks at the software documentation. The document explaining these questions is here.

Required questions are;

  1. Is there a whitepaper? (Y/N)

  2. Are the basic software functions documented? (Y/N)

  3. Does the software function documentation fully (100%) cover the deployed contracts? (%)

  4. Are there sufficiently detailed comments for all functions within the deployed contract code (%)

  5. Is it possible to trace from software documentation to the implementation in codee (%)

Is there a whitepaper? (Y/N)

Answer: Yes

Location: Their whitepaper is both their Documentation, as well as the Whitepaper.

Are the basic software functions documented? (Y/N)

Answer: Yes

Location: https://docs.bancor.network/ethereum-contracts/ethereum-api-reference

Does the software function documentation fully (100%) cover the deployed contracts? (%)

Answer: 100%

The requirements are extremely well explained in the Bancor API. All of the specific contracts have detailed explanations with reference to the code within them. This is extremely well organized, and well written documentation.

Guidance:

100% All contracts and functions documented 80% Only the major functions documented 79-1% Estimate of the level of software documentation 0% No software documentation

Are there sufficiently detailed comments for all functions within the deployed contract code (%)

Answer: 80%

There are detailed comments documenting the functions on all level of code.

Code examples are in the Appendix. As per the SLOC, there is 73% commenting to code (CtC).

The Comments to Code (CtC) ratio is the primary metric for this score.

Guidance: 100% CtC > 100 Useful comments consistently on all code 90-70% CtC > 70 Useful comment on most code 60-20% CtC > 20 Some useful commenting 0% CtC < 20 No useful commenting

How to improve this score

This score can improve by adding comments to the deployed code such that it comprehensively covers the code. For guidance, refer to the SecurEth Software Requirements.

Is it possible to trace from software documentation to the implementation in code (%)

Answer: 100%

The API specifically defines all parts of the code. there is clear traceability throughout all of the documentation.

Guidance: 100% - Clear explicit traceability between code and documentation at a requirement level for all code 60% - Clear association between code and documents via non explicit traceability 40% - Documentation lists all the functions and describes their functions 0% - No connection between documentation and code

Testing

This section looks at the software testing available. It is explained in this document. This section answers the following questions;

  1. Full test suite (Covers all the deployed code) (%)

  2. Code coverage (Covers all the deployed lines of code, or explains misses) (%)

  3. Scripts and instructions to run the tests (Y/N)

  4. Packaged with the deployed code (Y/N)

  5. Report of the results (%)

  6. Formal Verification test done (%)

  7. Stress Testing environment (%)

Is there a Full test suite? (%)

Answer: 100%

As per the Appendix, The test to code ratio is 319%.

This score is guided by the Test to Code ratio (TtC). Generally a good test to code ratio is over 100%. However the reviewers best judgement is the final deciding factor.

Guidance: 100% TtC > 120% Both unit and system test visible 80% TtC > 80% Both unit and system test visible 40% TtC < 80% Some tests visible 0% No tests obvious

How to improve this score

This score can improve by adding tests to fully cover the code. Document what is covered by traceability or test results in the software repository.

Code coverage (Covers all the deployed lines of code, or explains misses) (%)

Answer: 50%

As there is no indication of code coverage, a 50% score is given.

Guidance: 100% - Documented full coverage 99-51% - Value of test coverage from documented results 50% - No indication of code coverage but clearly there is a reasonably complete set of tests 30% - Some tests evident but not complete 0% - No test for coverage seen

How to improve this score

This score can improve by adding tests achieving full code coverage. A clear report and scripts in the software repository will guarantee a high score.

Scripts and instructions to run the tests (Y/N)

Answer: Yes

Instructions on how to run the testing is found in Bancor's documentation.

Packaged with the deployed code (Y/N)

Answer: Yes

The testing is packaged with the deployed code.

Report of the results (%)

Answer: 90%

A test report is found at : https://github.com/bancorprotocol/solidity-test-reports. The report lists all test complete on a standard run but does not indicate coverage (this ran previously but did not run when generated for this report. It may be added in the future.

How to improve this score

Add a report with the results. The test scripts should generate the report or elements of it.

Formal Verification test done (%)

Answer: 0%

There is no evidence of formal verification testing having been done in their external documentation.

Stress Testing environment (%)

Answer: 100%

There is evidence of stress testing done on the Roptsen network.

Audits

Answer: 100%

There are 5 different audits published. Links can be found in the Security Page.

Guidance:

  1. Multiple Audits performed before deployment and results public and implemented or not required (100%)

  2. Single audit performed before deployment and results public and implemented or not required (90%)

  3. Audit(s) performed after deployment and no changes required. Audit report is public. (70%)

  4. No audit performed (20%)

  5. Audit Performed after deployment, existence is public, report is not public and no improvements deployed OR smart contract address' not found, question 1 (0%)

Appendices

Author Details

The author of this review is Rex of Caliburn Consulting.

Email : rex@defisafety.com Twitter : @defisafety

I started with Ethereum just before the DAO and that was a wonderful education. It showed the importance of code quality. The second Parity hack also showed the importance of good process. Here my aviation background offers some value. Aerospace knows how to make reliable code using quality processes.

I was coaxed to go to EthDenver 2018 and there I started SecuEth.org with Bryant and Roman. We created guidelines on good processes for blockchain code development. We got EthFoundation funding to assist in their development.

Process Quality Reviews are an extension of the SecurEth guidelines that will further increase the quality processes in Solidity and Vyper development.

Career wise I am a business development manager for an avionics supplier.

Scoring Appendix

Executing Code Appendix

Code Used Appendix

Example Code Appendix

// SPDX-License-Identifier: SEE LICENSE IN LICENSE
pragma solidity 0.6.12;
import "./interfaces/IBancorXUpgrader.sol";
import "./interfaces/IBancorX.sol";
import "../utility/ContractRegistryClient.sol";
import "../utility/SafeMath.sol";
import "../utility/TokenHandler.sol";
import "../utility/TokenHolder.sol";
/**
* @dev The BancorX contract allows cross chain token transfers.
*
* There are two processes that take place in the contract -
* - Initiate a cross chain transfer to a target blockchain (locks tokens from the caller account on Ethereum)
* - Report a cross chain transfer initiated on a source blockchain (releases tokens to an account on Ethereum)
*
* Reporting cross chain transfers works similar to standard multisig contracts, meaning that multiple
* callers are required to report a transfer before tokens are released to the target account.
*/
contract BancorX is IBancorX, TokenHandler, TokenHolder, ContractRegistryClient {
using SafeMath for uint256;
// represents a transaction on another blockchain where tokens were destroyed/locked
struct Transaction {
uint256 amount;
bytes32 fromBlockchain;
address to;
uint8 numOfReports;
bool completed;
}
uint16 public constant version = 4;
uint256 public maxLockLimit; // the maximum amount of tokens that can be locked in one transaction
uint256 public maxReleaseLimit; // the maximum amount of tokens that can be released in one transaction
uint256 public minLimit; // the minimum amount of tokens that can be transferred in one transaction
uint256 public prevLockLimit; // the lock limit *after* the last transaction
uint256 public prevReleaseLimit; // the release limit *after* the last transaction
uint256 public limitIncPerBlock; // how much the limit increases per block
uint256 public prevLockBlockNumber; // the block number of the last lock transaction
uint256 public prevReleaseBlockNumber; // the block number of the last release transaction
uint8 public minRequiredReports; // minimum number of required reports to release tokens
IERC20Token public override token; // erc20 token
bool public xTransfersEnabled = true; // true if x transfers are enabled, false if not
bool public reportingEnabled = true; // true if reporting is enabled, false if not
// txId -> Transaction
mapping (uint256 => Transaction) public transactions;
// xTransferId -> txId
mapping (uint256 => uint256) public transactionIds;
// txId -> reporter -> true if reporter already reported txId
mapping (uint256 => mapping (address => bool)) public reportedTxs;
// address -> true if address is reporter
mapping (address => bool) public reporters;
/**
* @dev triggered when tokens are locked in smart contract
*
* @param _from wallet address that the tokens are locked from
* @param _amount amount locked
*/
event TokensLock(
address indexed _from,
uint256 _amount
);
/**
* @dev triggered when tokens are released by the smart contract
*
* @param _to wallet address that the tokens are released to
* @param _amount amount released
*/
event TokensRelease(
address indexed _to,
uint256 _amount
);
/**
* @dev triggered when xTransfer is successfully called
*
* @param _from wallet address that initiated the xtransfer
* @param _toBlockchain target blockchain
* @param _to target wallet
* @param _amount transfer amount
* @param _id xtransfer id
*/
event XTransfer(
address indexed _from,
bytes32 _toBlockchain,
bytes32 indexed _to,
uint256 _amount,
uint256 _id
);
/**
* @dev triggered when report is successfully submitted
*
* @param _reporter reporter wallet
* @param _fromBlockchain source blockchain
* @param _txId tx id on the source blockchain
* @param _to target wallet
* @param _amount transfer amount
* @param _xTransferId xtransfer id
*/
event TxReport(
address indexed _reporter,
bytes32 _fromBlockchain,
uint256 _txId,
address _to,
uint256 _amount,
uint256 _xTransferId
);
/**
* @dev triggered when final report is successfully submitted
*
* @param _to target wallet
* @param _id xtransfer id
*/
event XTransferComplete(
address _to,
uint256 _id
);
/**
* @dev initializes a new BancorX instance
*
* @param _maxLockLimit maximum amount of tokens that can be locked in one transaction
* @param _maxReleaseLimit maximum amount of tokens that can be released in one transaction
* @param _minLimit minimum amount of tokens that can be transferred in one transaction
* @param _limitIncPerBlock how much the limit increases per block
* @param _minRequiredReports minimum number of reporters to report transaction before tokens can be released
* @param _registry address of contract registry
* @param _token erc20 token
*/
constructor(
uint256 _maxLockLimit,
uint256 _maxReleaseLimit,
uint256 _minLimit,
uint256 _limitIncPerBlock,
uint8 _minRequiredReports,
IContractRegistry _registry,
IERC20Token _token
) ContractRegistryClient(_registry)
public
greaterThanZero(_maxLockLimit)
greaterThanZero(_maxReleaseLimit)
greaterThanZero(_minLimit)
greaterThanZero(_limitIncPerBlock)
greaterThanZero(_minRequiredReports)
validAddress(address(_token))
notThis(address(_token))
{
// validate input
require(_minLimit <= _maxLockLimit && _minLimit <= _maxReleaseLimit, "ERR_INVALID_MIN_LIMIT");
// the maximum limits, minimum limit, and limit increase per block
maxLockLimit = _maxLockLimit;
maxReleaseLimit = _maxReleaseLimit;
minLimit = _minLimit;
limitIncPerBlock = _limitIncPerBlock;
minRequiredReports = _minRequiredReports;
// previous limit is _maxLimit, and previous block number is current block number
prevLockLimit = _maxLockLimit;
prevReleaseLimit = _maxReleaseLimit;
prevLockBlockNumber = block.number;
prevReleaseBlockNumber = block.number;
token = _token;
}
// validates that the caller is a reporter
modifier reporterOnly {
_reporterOnly();
_;
}
// error message binary size optimization
function _reporterOnly() internal view {
require(reporters[msg.sender], "ERR_ACCESS_DENIED");
}
// allows execution only when x transfers are enabled
modifier xTransfersAllowed {
_xTransfersAllowed();
_;
}
// error message binary size optimization
function _xTransfersAllowed() internal view {
require(xTransfersEnabled, "ERR_DISABLED");
}
// allows execution only when reporting is enabled
modifier reportingAllowed {
_reportingAllowed();
_;
}

SLOC Appendix

Solidity Contracts

Language

Files

Lines

Blanks

Comments

Code

Complexity

Solidity

14

6663

744

2517

3402

396

Comments to Code 2517/ 3402 = 73%

Javascript Tests

Language

Files

Lines

Blanks

Comments

Code

Complexity

JavaScript

45

13798

2773

171

10854

731

Tests to Code 10854 / 3402 = 319%