Multichain bridge implementing Across protocol

Test

$ make test-all

Deploy

$ make deploy-all

Back-end integration

Before interacting with contract, back-end must collect data.

Let's say depositor wants to bridge tokenAmount of tokenAddress from originChainId to destinationChainId.

Back-end will first call our AcrossRelayer contract. The method getInputAmount with input param the total tokenAmount will return 2 outputs :

• the acrossAmount that is tokenAmount - feeAmount
• the feeAmount which AccrosRelayer will send to fee receiver

Then, let's fetch suggested-fees from API : https://app.across.to/api/suggested-fees?token=${tokenAddress}&originChainId=${originChainId}&destinationChainId=${destinationChainId}&amount=${acrossAmount}

This will provide the 2 following parameters to call brigdeNative and bridgeERC20 :

• totalRelayFee.total used as _relayFee in our contract
• timestamp used as _quoteTimestamp in our app

Notes

To bridge native tokens, user must call bridgeNative method, with msg.value > 0.

To bridge ERC20 tokens, user must call bridgeERC20 method, with according _tokenAddress and _inputAmount. But first he must approve AcrossRelayer contract to spend his tokens.

SpokePool on Polygon does not have enabled deposit routes for native tokens at the moment.