Float Capital 🌊

"Float like a butterfly, stake like bee" - Team float

Useful links ⭐️

🌊 float.capital • @float_capital • discord • documentation • Youtube videos• Testnet Application (on Mumbai Testnet) 📚

Float Capital contest details

• $45,000 main award pot 💰💰💰
• $5,000 gas optimization award pot 💰
• Join C4 Discord to register
• Submit findings using the C4 form
• Read our guidelines for more details 🤓
• Starts 2021-08-05 00:00 UTC 🚨
• Ends 2021-08-11 23:59 UTC 🚨

Hello Wardens 👋

Yes! You're here! Awesome. We are super excited for your journey on unpacking and dissecting our code. We will do our best to be available around the clock for all your questions, small, big, silly or severe.

For a verbose walkthrough of the system be sure to watch the videos that will take you through the system in finer details. We recommend starting here and playing around with the currently deployed mumbai testnet version.

We wish you luck on your audit.

Happy hunting 🕵

Float Capital team

Contact us ☎️

Discord handles and timezones incoming:

• @jonjon#2270 (GMT+1)
• @Jason |float.capital & wildcards#3836 (GMT+2)
• @! Denham | float.capital#5167 (GMT+2)
• @Paul | float.capital#8113 (GMT+2)
• @stento#9884 (GMT+3)
• @MJ Young#3116 (GMT+2)
• @Woo Sung | float.capital#7210 (GMT+9)

Timezones don't mean much for us nocturnal solidity wizards so feel free to ping us absolutely whenever.

Happy to arrange video calls if you want to disscuss something more deeply.

Contest Scope

The following contracts are in scope (with their line counts):

File	Blank lines	comments	All lines of code (excluding Blank Lines and Comments)	statements	branches	functions	Lines (excluding global variable declarations, function signatures , run over lines and event definitions)
LongShort.sol	167	332	739	214	70	45	217
Staker.sol	153	272	552	184	64	41	188
TokenFactory.sol	13	31	33	9	2	3	10
YieldManagerAave.sol	40	79	97	42	10	8	43
FloatToken.sol	9	30	30	10	2	3	10
SyntheticToken.sol	12	60	60	16	6	7	16
TOTAL	394	804	1511	475	154	107	484

• counted using cloc and solidity-coverage

If you have any questions about the scope, just shoot us a message!

Protocol summary

Put simply, Float is the easiest and safest way for users to mint synthetic assets. Users do not need to worry about over-collateralization, or suddenly getting liquidated.

In its most basic form, the Float protocol creates a 'peer-to-peer' exposure market where long positions on one synthetic asset, are offset by short positions on that same synthetic asset (synth). For example, Imagine Alice has $100 000 of short exposure to a synth, while Bob had $100 000 of long exposure to this synth. Given this, a 1% decrease in the underlying asset price would mean that Alice now has $101 000 of value while bob has $99 000 of value.

We refer you to the documentation for finer details.

Video walk-throughs of smart-contracts 📼

If you are a visual learner, you may prefer to watch our video walk through series. This is a super comprehensive resource for understanding the protocol. We give a high level overview before diving in to the code. Only thing left is to go catch those 🐛

• Very professional youtube videos

We are open to requests to create videos on specific parts of the code that you feel you need more clarity on.

Smart contract summary

LongShort.sol

The biggest contract where most of the good stuff happens! This is the best place to start. Here a user can mint a position and redeem their position.

Staker.sol

The second biggest contract, another important one! Users can stake their synthetic assets to earn FLT tokens! This contract manages all of this logic.

TokenFactory.sol

A simple contract to create a pair new ERC20 tokens, one ERC20 token representing the long position, the other representing the short position. Everytime a new synthetic asset is created, the token factory will deploy the requisite pair of ERC20 tokens.

YieldManagerAave.sol

All underlying deposits into the system used to mint a position, are automatically sent to the yield manager. The yield manager lends funds out to aave, and helps us keep track of how much yield we have earned.

FloatToken.sol

This is the reward token, FLT, that we mint and give users, based on them locking up their synthetic assets in the staker.

SyntheticToken.sol

This is the modified ERC20 token that the token factory is deploying.

Known trade-offs in the current design 🎚️

• System does not allow price updates that are greater than 100%.

  Mitigation - if the price moves more than 100% in our code we action a price movement of 99.99% which wipes out almost all the liquidity on one side of the market. But it doesn't destroy the market.

• Oracles are unreliable, faulty, manipulatable etc

  Mitigation - we use a reputable 3rd party to handle this difficult part for us - namely Chainlink.

• The underlying yield mechanism might undergo breaking changes or updates

  Mitigation - we use a 'yield manager' per market so this can evolve and develop over time.

• The oracle interface may change over time

  Mitigation - we use a 'oracle manager' per market so this can be updated when necessary.

Preemptive questions and answers ❓

• Why do a lot of the functions have virtual modifiers?

The virtual modifiers exist as part of our development test environment framework. It allows us to unit test core code by overriding these functions in code generated mocks.

• Why don't you check boolean return status for erc20 methods?

We only check the return boolean (success) for erc20 methods on the payment token not for the synthetic token - this is safe since the synthetic token is written to never return false.

• Why is long & short represented as a boolean and not an enum?

Enum's within mappings break hardhat stack traces

Other notes and thoughts 💭

• Currently our synthetic tokens are inheriting from the open zeppelin ERC20PresetMinterPauser contract, but the pause functionality has been stripped out by our use of _beforeTokenTransfer. We have left the contracts inheriting from the MinterPauser because there is some chance we will add pause functionality before launch - we just want to make sure we don't expose the system to unnecessary external risk - results from various audits will guide this decision. If we don't launch a pausable synth token we will inherit from a more basic ERC20 implementation.

• All our floating point arithmetic is using base 1e18. Additionally, in solidity, integer division rounds down - this is a potential source of bugs! For example, things to look out for, (a+b+c)/d != a/d+b/d+c/d in solidity, rather (a+b+c)/d >= a/d+b/d+c/d. Also when composing and optimising division and multiplication operations using, canceling out the 1e18 can lead to different output for different input - (numerator / 1e18) * 1e18 / denominator != numerator / denominator if the numerator is < 1e18 (as seen in the _getEquivalentAmountSyntheticTokensOnTargetSide function).

• We use mappings of single values almost everywhere. There are lots of places that structs could potentially be used. Our initial version of these contracts used structs, however it became quite unwieldy. Examples include batched_* and userNextPrice_ variables in LongShort.sol and stakerTokenShiftIndex_*, userNextPrice_* variables in Staker.sol.

• We use a unique method for unit testing. If you are interested in how we unit test you can watch this youtube video - the framework is a WIP - but it does its job. We use smock for smocking and some auto-generated code to unit test internal functions (see contracts/testing/generated/LongShortForInternalMocking.sol and contracts/testing/generated/LongShortMockable.sol as an example). This is why we make almost all of our functions virtual - this doesn't affect the security of our contracts once deployed, but it does mean that users who inherit these contracts must take extra care. The virtual keyword was added to solidity 0.6 to make it clear to developers what functions should or shouldn't be inherited.

• FLT token issuance rate maths is here in latex. This is quite a beast and we are working on a youtube video explaining the logic behind it. The premise is the side supplying more valuable liquidity (the underbalanced side) should earn more FLT by staking per dollar staked as opposed to overbalanced side liquidity being staked. This is to incentivize equal liquidity in long and short positions. The purpose of this function is that it has a horizontal offset and exponent that basically allow us 'tweak' these incentives as we understand how the market reacts to them. The horizontal offset allows us to account for an asymmetric demand and supply, where even at 50/50 liquidity, we might reward one side more due to natural tendency to favour that position. The exponent dictates how strong we want the incentive to be.

• The contracts are intended to be used with DAI and potentially other ERC20 payment tokens with 18 decimal places.

• Internal governance will be managed by a Gnosis Safe with 3 signers of 5 owners affording diversified security and sufficient recoverability. In case of blackswan events as a last resort we can upgrade contracts to block functionality.

• We have very strict criteria for what is accetpable as a payment token. It MUST be base 10^18, it MUST return a success boolean on transfer, it MUSTN'T be pausable, it MUSTN'T take fees on transfers and due to the initial market liquidity requirement payment tokens with unreasonably high prices (eg BTC) might not be practical. We also have a total market size limit of 10 Trillion (10^13 tokens, or 10^31) so if a payment token has a price that is too low and there is chance that markets get close to that limit we will either need to update the mechanism by which we choose the safeExponentBitShifting (which is currently hardcoded). We are aware of this and have will ONLY use DAI for initial markets.

External calls made by our contracts:

• Aave:

  • Deposit into Aave lending pool

  • Withdraw from Aave lending pool

• Chainlink:

  • ‘latestRoundData’ on Chainlink V3 aggregator contracts (via OracleManager - a very very thin wrapper around chainlink oracles - implemented this way for flexibility and evolving oracles)

Base contracts

We use OpenZeppelin where possible.

External Risks

We use ChainLink as our oracle.

Network

We intend to deploy these contracts to Polygon. Existing testnet is deployed to Mumbai at https://float.capital.

Setup

See Contracts README.md

How to run the tests

cd contracts yarn (install all dependencies) yarn test

To test deploying this code to a testnet run truffle develop then inside the integrated terminal run migrate.

Note on tests Some of the test are written in truffle (those are the very old tests - most of them can be deprecated), the rest are written with hardhat-waffle (written with Rescript but with vendored javascript for convenience).