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AcrossFacet.md

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Across Facet

How it works

The Across Facet works by forwarding Across specific calls to one of Across SpokePools. All bridging is done by calling the deposit method.

graph LR;
    D{LiFiDiamond}-- DELEGATECALL -->AcrossFacet;
    AcrossFacet -- CALL --> C(Across)
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Public Methods

  • function startBridgeTokensViaAcross(BridgeData memory _bridgeData, AcrossData calldata _acrossData)
    • Simply bridges tokens using Across
  • swapAndStartBridgeTokensViaAcross(BridgeData memory _bridgeData, SwapData[] calldata _swapData, AcrossData calldata _acrossData)
    • Performs swap(s) before bridging tokens using Across

Across Specific Parameters

The methods listed above take a variable labeled _acrossData. This data is specific to Across and is represented as the following struct type:

/// @param relayerFeePct The relayer fee in token percentage with 18 decimals.
/// @param quoteTimestamp The timestamp associated with the suggested fee.
/// @param message Arbitrary data that can be used to pass additional information to the recipient along with the tokens.
/// @param maxCount Used to protect the depositor from frontrunning to guarantee their quote remains valid.
struct AcrossData {
  int64 relayerFeePct;
  uint32 quoteTimestamp;
  bytes message;
  uint256 maxCount;
}

Swap Data

Some methods accept a SwapData _swapData parameter.

Swapping is performed by a swap specific library that expects an array of calldata to can be run on various DEXs (i.e. Uniswap) to make one or multiple swaps before performing another action.

The swap library can be found here.

LiFi Data

Some methods accept a BridgeData _bridgeData parameter.

This parameter is strictly for analytics purposes. It's used to emit events that we can later track and index in our subgraphs and provide data on how our contracts are being used. BridgeData and the events we can emit can be found here.

Getting Sample Calls to interact with the Facet

In the following some sample calls are shown that allow you to retrieve a populated transaction that can be sent to our contract via your wallet.

All examples use our /quote endpoint to retrieve a quote which contains a transactionRequest. This request can directly be sent to your wallet to trigger the transaction.

The quote result looks like the following:

const quoteResult = {
  id: '0x...', // quote id
  type: 'lifi', // the type of the quote (all lifi contract calls have the type "lifi")
  tool: 'across', // the bridge tool used for the transaction
  action: {}, // information about what is going to happen
  estimate: {}, // information about the estimated outcome of the call
  includedSteps: [], // steps that are executed by the contract as part of this transaction, e.g. a swap step and a cross step
  transactionRequest: {
    // the transaction that can be sent using a wallet
    data: '0x...',
    to: '0x...',
    value: '0x00',
    from: '{YOUR_WALLET_ADDRESS}',
    chainId: 100,
    gasLimit: '0x...',
    gasPrice: '0x...',
  },
}

A detailed explanation on how to use the /quote endpoint and how to trigger the transaction can be found here.

Hint: Don't forget to replace {YOUR_WALLET_ADDRESS} with your real wallet address in the examples.

Cross Only

To get a transaction for a transfer from 30 USDC.e on Avalanche to USDC on Binance you can execute the following request:

curl 'https://li.quest/v1/quote?fromChain=AVA&fromAmount=30000000&fromToken=USDC&toChain=BSC&toToken=USDC&slippage=0.03&allowBridges=across&fromAddress={YOUR_WALLET_ADDRESS}'

Swap & Cross

To get a transaction for a transfer from 30 USDT on Avalanche to USDC on Binance you can execute the following request:

curl 'https://li.quest/v1/quote?fromChain=AVA&fromAmount=30000000&fromToken=USDT&toChain=BSC&toToken=USDC&slippage=0.03&allowBridges=across&fromAddress={YOUR_WALLET_ADDRESS}'