This is a Yearn V2 Process Quality Review completed on 27 January, 2021. It was performed using the Process Review process (version 0.6.1) and is documented here. The review was performed by ShinkaRex of DeFiSafety. Check out our Telegram. The previous version of the review (0Yearn V1) is here.
The final score of the review is 93%, a super solid score. The breakdown of the scoring is in Scoring Appendix.
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
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, token, 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. The views expressed within this report are limited to DeFiSafety and the author and do not reflect those of any additional or third party and are strictly based upon DeFiSafety, its authors, interpretations and evaluation of relevant data. 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.
This completed report is copyright (c) DeFiSafety 2021. Permission is given to copy in whole, retaining this copyright label.
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;
Are the executing code addresses readily available? (Y/N)
Is the code actively being used? (%)
Is there a public software repository? (Y/N)
Is there a development history visible? (%)
Is the team public (not anonymous)? (Y/N)
They are available at website https://docs.yearn.finance/developers/deployed-contracts-registry as indicated in the Appendix.
Activity is 25 transactions a day on contract yVault.sol, as indicated in the Appendix.
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 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.
With 183 commits and 4 branches, 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
The Yearn team is found on https://docs.yearn.finance/additional-resources/team
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 is a No.
This section looks at the software documentation. The document explaining these questions is here.
Required questions are;
Is there a whitepaper? (Y/N)
Are the basic software functions documented? (Y/N)
Does the software function documentation fully (100%) cover the deployed contracts? (%)
Are there sufficiently detailed comments for all functions within the deployed contract code (%)
Is it possible to trace from software documentation to the implementation in codee (%)
There are a few places to view the software function documentation, most notably in their yVault Documentation, as well as the rest of the "developers" secton in their documentation.
The major contracts are well documented in their documentation, but there are many smaller contracts that are missing software function documentation. The yVaults have the most robust documentation of yearn's contracts.
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
This score can improve by adding content to the requirements document such that it comprehensively covers the requirements. For guidance, refer to the SecurEth System Description Document . Using tools that aid traceability detection will help.
The CtC seems to understate how much commenting there is on the Vyper code. For this reason the score was increase to 70%.
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
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.
There is clear tractability for their v2 contracts in their documentation for all of their major contracts
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
This score can improve by adding traceability from requirements to code such that it is clear where each requirement is coded. For reference, check the SecurEth guidelines on traceability.
This section looks at the software testing available. It is explained in this document. This section answers the following questions;
Full test suite (Covers all the deployed code) (%)
Code coverage (Covers all the deployed lines of code, or explains misses) (%)
Scripts and instructions to run the tests (Y/N)
Packaged with the deployed code (Y/N)
Report of the results (%)
Formal Verification test done (%)
Stress Testing environment (%)
TtC is 100%, python to vyper. We are learning that python testing lis by the line
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
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.
The code coverage report is found by expanding the "Run Tests" element of this report. Not user friendly but it is still new with Vyper and Brownie.
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
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.
Testing instructions can be found in their github.
Add the scripts to the repository and ensure they work. Ask an outsider to create the environment and run the tests. Improve the scripts and docs based on their feedback.
The tests are packaged with the deployed repository in github.
Improving this score requires redeployment of the code, with the tests. This score gives credit to those who test their code before deployment and release them together. If a developer adds tests after deployment they can gain full points for all test elements except this one.
Buried in the actions there is a test report. However it is not published neatly and the content is limited, though it does have the list of tests and coverage results. For this reason a score of 60% is given.
Guidance: 100% - Detailed test report as described below 70% - GitHub Code coverage report visible 0% - No test report evident
Add a report with the results. The test scripts should generate the report or elements of it.
There is no formal verification testing evident.
No active test networks are evident.
Yearn V2 has been audited by:
Multiple Audits performed before deployment and results public and implemented or not required (100%)
Single audit performed before deployment and results public and implemented or not required (90%)
Audit(s) performed after deployment and no changes required. Audit report is public. (70%)
No audit performed (20%)
Audit Performed after deployment, existence is public, report is not public and no improvements deployed OR smart contract address' not found, question 1 (0%)
The author of this review is Rex of DeFi Safety.
Email : [email protected]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.
DeFiSafety is my full time gig and we are working on funding vehicles for a permanent staff.
# @version 0.2.8"""@title Yearn Token Vault@license GNU AGPLv3@author yearn.finance@noticeYearn Token Vault. Holds an underlying token, and allows users to interactwith the Yearn ecosystem through Strategies connected to the Vault.Vaults are not limited to a single Strategy, they can have as many Strategiesas can be designed (however the withdrawal queue is capped at 20.)Deposited funds are moved into the most impactful strategy that has notalready reached its limit for assets under management, regardless of whichStrategy a user's funds end up in, they receive their portion of yieldsgenerated across all Strategies.When a user withdraws, if there are no funds sitting undeployed in theVault, the Vault withdraws funds from Strategies in the order of leastimpact. (Funds are taken from the Strategy that will disturb everyone'sgains the least, then the next least, etc.) In order to achieve this, thewithdrawal queue's order must be properly set and managed by the community(through governance).Vault Strategies are parameterized to pursue the highest risk-adjusted yield.There is an "Emergency Shutdown" mode. When the Vault is put into emergencyshutdown, assets will be recalled from the Strategies as quickly as ispractical (given on-chain conditions), minimizing loss. Deposits arehalted, new Strategies may not be added, and each Strategy exits with theminimum possible damage to position, while opening up deposits to bewithdrawn by users. There are no restrictions on withdrawals above what isexpected under Normal Operation.For further details, please refer to the specification:https://github.com/iearn-finance/yearn-vaults/blob/master/SPECIFICATION.md"""API_VERSION: constant(String) = "0.3.0"from vyper.interfaces import ERC20implements: ERC20interface DetailedERC20:def name() -> String: viewdef symbol() -> String: viewdef decimals() -> uint256: viewinterface Strategy:def want() -> address: viewdef vault() -> address: viewdef estimatedTotalAssets() -> uint256: viewdef withdraw(_amount: uint256) -> uint256: nonpayabledef migrate(_newStrategy: address): nonpayableinterface GuestList:def authorized(guest: address, amount: uint256) -> bool: view# NOTE: Track the total for overhead targeting purposesstrategies: public(HashMap[address, StrategyParams])MAXIMUM_STRATEGIES: constant(uint256) = 20# Ordering that `withdraw` uses to determine which strategies to pull funds from# NOTE: Does *NOT* have to match the ordering of all the current strategies that# exist, but it is recommended that it does or else withdrawal depth is# limited to only those inside the queue.# NOTE: Ordering is determined by governance, and should be balanced according# to risk, slippage, and/or volatility. Can also be ordered to increase the# withdrawal speed of a particular Strategy.# NOTE: The first time a ZERO_ADDRESS is encountered, it stops withdrawingwithdrawalQueue: public(address[MAXIMUM_STRATEGIES])emergencyShutdown: public(bool)depositLimit: public(uint256) # Limit for totalAssets the Vault can holddebtRatio: public(uint256) # Debt ratio for the Vault across all strategies (in BPS, <= 10k)totalDebt: public(uint256) # Amount of tokens that all strategies have borrowedlastReport: public(uint256) # block.timestamp of last reportactivation: public(uint256) # block.timestamp of contract deploymentrewards: public(address) # Rewards contract where Governance fees are sent to# Governance Fee for management of Vault (given to `rewards`)managementFee: public(uint256)# Governance Fee for performance of Vault (given to `rewards`)performanceFee: public(uint256)MAX_BPS: constant(uint256) = 10_000 # 100%, or 10k basis pointsSECS_PER_YEAR: constant(uint256) = 31_557_600 # 365.25 days# `nonces` track `permit` approvals with signature.nonces: public(HashMap[address, uint256])DOMAIN_SEPARATOR: public(bytes32)DOMAIN_TYPE_HASH: constant(bytes32) = keccak256('EIP712Domain(string name,string version,uint256 chainId,address verifyingContract)')PERMIT_TYPE_HASH: constant(bytes32) = keccak256("Permit(address owner,address spender,uint256 value,uint256 nonce,uint256 deadline)")@externaldef initialize(token: address,governance: address,rewards: address,nameOverride: String,symbolOverride: String,guardian: address = msg.sender,):"""@noticeInitializes the Vault, this is called only once, when the contract isdeployed.The performance fee is set to 10% of yield, per Strategy.The management fee is set to 2%, per year.The initial deposit limit is set to 0 (deposits disabled); it must beupdated after initialization.@devIf `nameOverride` is not specified, the name will be 'yearn'combined with the name of `token`.If `symbolOverride` is not specified, the symbol will be 'y'combined with the symbol of `token`.@param token The token that may be deposited into this Vault.@param governance The address authorized for governance interactions.@param rewards The address to distribute rewards to.@param nameOverride Specify a custom Vault name. Leave empty for default choice.@param symbolOverride Specify a custom Vault symbol name. Leave empty for default choice.@param guardian The address authorized for guardian interactions. Defaults to caller."""assert self.activation == 0 # dev: no devops199self.token = ERC20(token)if nameOverride == "":self.name = concat(DetailedERC20(token).symbol(), " yVault")else:self.name = nameOverrideif symbolOverride == "":self.symbol = concat("yv", DetailedERC20(token).symbol())else:self.symbol = symbolOverrideself.decimals = DetailedERC20(token).decimals()self.governance = governancelog UpdateGovernance(governance)self.management = governancelog UpdateManagement(governance)self.rewards = rewardslog UpdateRewards(rewards)self.guardian = guardianlog UpdateGuardian(guardian)self.performanceFee = 1000 # 10% of yield (per Strategy)log UpdatePerformanceFee(convert(1000, uint256))self.managementFee = 200 # 2% per yearlog UpdateManagementFee(convert(200, uint256))self.lastReport = block.timestampself.activation = block.timestamp
Comments to Code 476 / 2024 = 24%
Tests to Code 1833 / 1815 = 100.0%