BSC Arbitrageur with Flashswap Smart Contract

Refactored by Daniel Espendiller https://github.com/Haehnchen from the previous repo. I ported the code to hardhat environment for the same of efficient development. Please confirm the improvement that he had made.

You want to play with "millions" on the blockchain then try https://uniswap.org/docs/v2/smart-contract-integration/using-flash-swaps/. This contract is able to arbitrage between DEX on the blockchain without providing any own capital.

Disclaimer

This repo is not either an investment advice or a recommendation or solicitation to buy or sell any investment and should not be used in the evaluation of the merits of making any investment decision. It should not be relied upon for accounting, legal or tax advice or investment recommendations. The contents reflected herein are subject to change without being updated.

The codes are written for informational and educational purpose only, https and websocket endpoints might not work well if those endpoint have been depreciated. Please find other available endpoints in that case. Thanks for your understanding.

Links

• https://github.com/Haehnchen/uniswap-arbitrage-flash-swap
• https://github.com/yuyasugano/pancake-bakery-arbitrage
• https://github.com/Uniswap/uniswap-v2-periphery/blob/master/contracts/examples/ExampleFlashSwap.sol

Improvements

All examples are more or less overengineered for a quick start, so here we have a KISS solution.

• Parameterize key variables in Node.js script
• Reduce overall contract size for low gas fee on deployment
• Provide a on chain validation contract method to let nodes check arbitrage opportunities
• Stop arbitrage opportunity execution as soon as possible if its already gone to reduce gas fee on failure
• Interface callbacks for common DEX on "Binance Smart Chain" are included

Parameters

• DELAY - auto reconnection delay in ms
• MAX_ATTEMPTS - a number of attempts at maximum
• BLOCK_NUMBER - must be within set block number, out of block error occurs
• GAS_MULTIPLIER - multipler value for the gas price to estimate a gas cost
• EFFECTIVE_PROFIT - arbitrage run if your profit exceeds this value in USD (default: 0.6 USD)

Infrastructure

Basically arbitrage opportunity dont last long, your transaction must make it into the next block. So you have <3 seconds watching for opportunities, decide and execute transaction. Sometimes there are also a chance to 2-3 have block, see example below. You can change some parameters in main.js or test.js scripts

[7920960] [6/1/2021, 5:50:37 PM]: alive (bsc-ws-node.nariox.org) - took 308.42 ms
[7920991] [6/1/2021, 5:52:09 PM]: [bsc-ws-node.nariox.org] [BAKE/BNB ape>bakery] Arbitrage opportunity found! Expected profit: 0.007 $2.43 - 0.10%
[7920991] [6/1/2021, 5:52:09 PM] [bsc-ws-node.nariox.org]: [BAKE/BNB ape>bakery] and go:  {"profit":"$1.79","profitWithoutGasCost":"$2.43","gasCost":"$0.64","duration":"539.35 ms","provider":"bsc-ws-node.nariox.org"}
[7920992] [6/1/2021, 5:52:13 PM]: [bsc-ws-node.nariox.org] [BAKE/BNB ape>bakery] Arbitrage opportunity found! Expected profit: 0.007 $2.43 - 0.10%
[7920992] [6/1/2021, 5:52:13 PM] [bsc-ws-node.nariox.org]: [BAKE/BNB ape>bakery] and go:  {"profit":"$1.76","profitWithoutGasCost":"$2.43","gasCost":"$0.67","duration":"556.28 ms","provider":"bsc-ws-node.nariox.org"}
[7921000] [6/1/2021, 5:52:37 PM]: alive (bsc-ws-node.nariox.org) - took 280.54 ms

Requirements

• You have a time window of 1000ms every 3 seconds (blocktime on BSC) and you should make it into the next transaction
• Websocket connection is needed to listen directly for new incoming blocks (I choose Chainstack endpoints)
• Use a non public provider; or build your own node (light node helps) and better have multiple owns; let the fastest win
• Spread your transaction execution around all possible providers, first one wins (in any case transactions are only execute once based on nonce)
• Find suitable pairs with liquidity but not with much transaction
• You can play with full pair liquidity, but dont be too greedy think of a price impact you would have
• Common opportunities are just between 0,5 - 1%
• Do not estimate transaction fee, just calculate it once and provide a static gas limit. Simply its takes to long
• Payback is directly calculated by calling the foreign contracts so its project independent (no hardcoded fee calculation)
• The profit is transferred to the owner / creator of the contract (We configured this in .env file)

Function

The contract is plain and simple [contracts/Flashswap.sol] some basic hints:

Check arbitrage opportunity between DEX. Read only method the one blockchain

    function check(
        address _tokenPay, // source currency when we will get; example BNB
        address _tokenSwap, // swapped currency with the source currency; example BUSD
        uint _amountTokenPay, // example: BNB => 10 * 1e18
        address _sourceRouter,
        address _targetRouter
    ) public view returns(int, uint) {}

Starts the execution. You are able to estimate the gas usage of the function, its also directly validating the opportunity. Its slow depending on connected nodes.

    function startArbitrage(
        uint _maxBlockNumber,
        address _tokenPay, // source currency when we will get; example BNB
        address _tokenSwap, // swapped currency with the source currency; example BUSD
        uint _amountTokenPay, // example: BNB => 10 * 1e18
        address _sourceRouter,
        address _targetRouter,
        address _sourceFactory
    ) external {}

As all developers are lazy and just forking projects around without any rename a common implementation is possible. Basically the pair contract call the foreign method of the contract. You can find them the naming in any pair contract inside the swap() method.

Example: https://bscscan.com/address/0x0eD7e52944161450477ee417DE9Cd3a859b14fD0#code: if (data.length > 0) IPancakeCallee(to).pancakeCall(msg.sender, amount0Out, amount1Out, data);

Extend method if needed:

# internal callback 
function execute(address _sender, uint256 _amount0, uint256 _amount1, bytes calldata _data) internal {}

# foreign methods that get called
function pancakeCall(address _sender, uint256 _amount0, uint256 _amount1, bytes calldata _data) external {}
function uniswapV2Call(address _sender, uint256 _amount0, uint256 _amount1, bytes calldata _data) external {}

Run it

For the main network:

cp .env.template .env # replace values inside ".env"
node main.js

For the test network:

cp .env.template .env #replace values inside ".env" 
node test.js

started: wallet 0xXXXX - gasPrice 5000000000 - contract owner: 0xXXXX
[bsc-ws-node.nariox.org] You are connected on 0xXXXX
[8124531] [6/8/2021, 7:53:20 PM]: [bsc-ws-node.nariox.org] [BUSD/BNB pancake>panther] Arbitrage checked! Expected profit: -0.015 $-4.99 - -0.15%
[8124532] [6/8/2021, 7:53:21 PM]: [bsc-ws-node.nariox.org] [BUSD/BNB pancake>panther] Arbitrage checked! Expected profit: -0.015 $-4.99 - -0.15%
[8124533] [6/8/2021, 7:53:24 PM]: [bsc-ws-node.nariox.org] [BUSD/BNB pancake>panther] Arbitrage checked! Expected profit: -0.014 $-4.71 - -0.14%
[8124534] [6/8/2021, 7:53:27 PM]: [bsc-ws-node.nariox.org] [BUSD/BNB pancake>panther] Arbitrage checked! Expected profit: -0.014 $-4.61 - -0.14%

License

This library is licensed under the MIT License.