1Shot API Gas Station

The 1Shot API Gas Station contract is meant to be used with an x402 relayer gateway to allow users to swap ERC-20 tokens for native gas tokens when they don't have any funds to pay for transaction fees.

The Gas Station contract uses Li.Fi to perform swaps, and is designed to roughly mimic how the Permit2Proxy contract works in the Li.Fi periphery.

n8n

A complete n8n relayer workflow is provided here for serving the Gas Station as an API.

Gas Station Details

The GasStation1Shot.sol contract can only be used with ERC-20 tokens that are EIP-3009 compatible, (like USDC and USDT) and it is intended only to swap a users tokens into native coins.

There are three checks performed internally:

1. The function signature on the diamondCalldata is ensured to correspond to one of the Li.Fi functions which swap to native coins (the swap is guaranteed to produce native coins).
2. The recipient of the native tokens is ensured to be the same address as the address which signed the EIP-3009 authorization (the authorizor is guaranteed to be the recipient of the output of the swap).
3. All funds authorized to be swapped by the user are ensured to be swapped (i.e. the relayer cannot input diamondCalldata that will leave residual tokens in the Gas Station after the transaction).

The slippage and fee data is set by the person/relayer who submits the transaction and is not guaranteed for the end user since this would require a second signature for the user to sign. The intention is that this Gas Station swap contract would only be used to procure small amounts of native token, so there is low risk to the user to lose substantial funds.

Try It Out

You can try 1Shot API's Gas Station Webapp or hit the API directly with curl and a valid x402 header:

Note

Leave the x-payment header out to get back a swap quote in the 402 response.

# Be sure to put a valid x-payment header (https://1shotapi.com/tools)
# and also set appropriate values for the from/to chains, fromAddress and amount
curl -X POST \
  https://n8n.1shotapi.dev/webhook/gas-station \
  -H "x-payment: YOUR-BASE64-ENCODED-PAYMENT-PAYLOAD" \
  -H "User-Agent: CustomUserAgent/1.0" \
  -H "Accept: application/json" \
  -H "Content-Type: application/json" \
  -d '{
    "fromChain": "43114",
    "fromToken": "0x9702230A8Ea53601f5cD2dc00fDBc13d4dF4A8c7",
    "fromAmount": "1000000",
    "fromAddress": "0x55680c6b69d598c0b42f93cd53dff3d20e069b5b",
    "toChain": "43114"
  }'

Hardhat Cheatsheet

Try running some of the following tasks:

npx hardhat vars set INFURA_API_KEY
npx hardhat vars set PRIVATE_KEY
npx hardhat vars set ETHERSCAN_API_KEY
npx hardhat ignition deploy --deployment-id v2-chain-8453 ./ignition/modules/GasStation1Shot.ts --network base --strategy create2
npx hardhat ignition verify v2-chain-<chainId> --include-unrelated-contracts
npx hardhat x402-gas-station --tokenaddress 0x833589fcd6edb6e08f4c7c32d4f71b54bda02913 --amount 100000 --network base

Deployments:

V1

• Base - 0x4E43836F329B5f176A5d1a21519d0C61f819429C
• Arbitrum - 0x4E43836F329B5f176A5d1a21519d0C61f819429C
• Avalanche - 0x4E43836F329B5f176A5d1a21519d0C61f819429C

V2

• Base - 0x949EBD97b770bcA5146F24f4F9De815b3F457680
• Arbitrum - 0x949EBD97b770bcA5146F24f4F9De815b3F457680
• Avalanche - 0x949EBD97b770bcA5146F24f4F9De815b3F457680
• linea - 0x87435C81ef97D608E426f1f0e2185410C9Ba362A