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Setup

Setup

  1. forge install OpenZeppelin/openzeppelin-contracts
  2. forge install foundry-rs/forge-std
  3. forge test --mc TestCore

Integration

  1. Follow setup
  2. Add test helpers functions:
Contract Function
UniswapV2ERC20.sol mint()
  1. Remove test helpers from contract before deploying
  • I'm not responsible for what happens if you leave them in

Notes on Uniswap v2

Uniswap v2 is an AMM but some major changes and updates to the original. It's powered by a constant product formula x*y=Z.

Pairs:

Unlike Uniswap V1 where liquidity pools were between ETH and a single ERC20 token. It can now users can swap between any ERC20 and now uses WETH (wrapped Ether) instead of native ETH.

  • Useful for liquidity providers to maintain more diverse ERC20 token positions without any exposure to ETH.
  • Also improves prices because of routing through ETH for a swap between two other assets (fees & slippage on 2 separate pairs instead of one).
    • If two tokens are not paired directly and don't have a common pair between them they can be swapped along a path that could exist.

Oracles:

This is a new implementation that offers decentralized manipulation-resistant on-chain price feeds.

  • It measures prices when they are expensive to manipulate and accumulating historical data
  • Offers gas-efficient time-weighted averages of uniswap prices for any time interval
  • Uniswap v1 can't be used safely as a price oracle because the price can moe significantly in a short period of time
  • It measures (not store) market price at the beginning of each block (before any trades take place).
    • Thus making it expensive to manipulate because it was set by the last Tx in a previous block.
    • They would also have to make a bad trade at the end of the previous block and then be able to arbitrage it back in the next block
    • Attackers will lose to arbitrageurs and would have to selfishly mine two blocks in a row (has not be observed to date).
  • The end-of-block price is added to a single cumulative-price variable in the core contact weighted by the amount of time this price existed.
    • It represents a sum of the price for every second in the entire history of the contract.
    • This can be used by external contracts to track TWAPs across any time interval.
    • (priceCumulative2 - priceCumulative1) / (timestamp2 - timestamp1) = TWAP
    • Can be used for directly or as basis for moving averages (EMAs and SMAs)
  • Cost of attack:
    • Moving the price 5% on a 1-hour TWAP is about equal to the amount lost to arbitrage and fess for moving the price 5% every block for 1 hour.

Flash Swaps: Similar to flash loans where a user can with no upfront capital or constraints can borrow => arbitrage => return either of the token in the pair.

Split into Core & Periphery:

  • Core in where one can find the Pair and Factory contracts.
  • Periphery where one can find the router, oracle, migrator.

Changes From UNIv1-UNIv2:

UniTable

Extra Links:

Uniswap v2 Blog

Uniswap v2 whitepaper

Uniswap v2 Overview

Uniswap V1 to V3