Gas.zip LayerZero v2
Gas Reloader

Batched gas reloader for 50+ supported LayerZero v2 chains.

Overview

Gas.zip is the fastest one-stop gas refuel bridge for over 175+ chains. Gas.zip has a LayerZero gas reloader at https://lz.gas.zip, allowing users to bridge to mutiple LayerZero destination chains with a single inbound transaction. All software is licensed under MIT and is verified on-chain at the respective addresses.

Additional documentation and implementations can be found at https://dev.gas.zip.

Depositing to Gas LayerZero v2

All sendDeposits() calls into the Gas LayerZero contract and must be encoded as a uint256 where the leftmost 16 bits are the destination chain ID and the rightmost 240 bits are the amount (in wei) you'd like to recieve on the destination chain.

Example of Process

1. Select the Source Chain: Start by selecting your source chain to deposit from.

2. Select the Destination Chains: Select your destination chains to recieve funds. In the example, these are Gnosis (v2 LZ chain ID 30145) and Fuse (v2 LZ chain ID 30138).

3. Select the Amount: Decide the amount of native currency you want to send to each chain. In the example, 0.000002 ETH is the amount bridged to both Gnosis and Fuse. The Ether input for each chain must be converted to Wei.

4. Estimate Fees: Call the estimateFees() function with the correct parameters. This function takes three arguments: v2LZids, messages and options. The aggregated return from estimateFees() is used as a parameter in sendDeposits().

5. Check Wallet Balance: Ensure your wallet balance exceeds the estimated fees plus the total value in Wei, else the contract will revert due to insufficent funds.

6. Proceed with the Transaction: After all the checks, proceed with the transaction by calling the sendDeposits() function with the correct parameters.

Complete Flow Code Example v2

Below is a complete logic transaction flow into the LayerZero Gas.zip contract that handles estimateFees() prior to calling sendDeposits().

import { encodePacked, parseEther, http, createWalletClient, publicActions } from 'viem'
import { optimism } from 'viem/chains'
import { privateKeyToAccount } from 'viem/accounts'
import { estimateFeesAbi, lzDepositAbi } from './abis'
 
const account = privateKeyToAccount('0x...')
 
const client = createWalletClient({
  account,
  chain: optimism,
  transport: http(),
}).extend(publicActions)
 
type ChainParams = {
  [key: string]: {
    v2LZid: number
    chainId: string
    valueInEther: string
  }
}
 
const contractParams: ChainParams = {
  gnosis: {
    v2LZid: 30145,
    chainId: '100',
    valueInEther: '0.000002',
  },
  fuse: {
    v2LZid: 30138,
    chainId: '122',
    valueInEther: '0.000002',
  },
}
 
// Estimate
const createReceiveOptions = (gasLimit: bigint) => {
  return encodePacked(
    ['bytes', 'uint8', 'uint16', 'uint8', 'bytes'],
    [encodePacked(['uint16'], [3]), 1, 16 + 1, 1, encodePacked(['uint128'], [gasLimit])],
  )
}
 
const createNativeOptions = (gasLimit: bigint, amount: bigint, to: string) => {
  return encodePacked(
    ['bytes', 'uint8', 'uint16', 'uint8', 'bytes'],
    [
      createReceiveOptions(gasLimit),
      1,
      32 + 16 + 1,
      2,
      encodePacked(['uint128', 'bytes32'], [amount, `0x${to.slice(2).padStart(64, '0')}` as `0x${string}`]),
    ],
  )
}
 
async function estimateFees(): Promise<bigint> {
  const nullAddress = '0x0000000000000000000000000000000000000000'
  const feeChains: {
    v2LZid: number
    chainId: string
  }[] = []
  const options: `0x${string}`[] = []
  const messages: `0x${string}`[] = []
 
  for (const chain in contractParams) {
    const selection = contractParams[chain]
    feeChains.push({
      v2LZid: selection.v2LZid,
      chainId: selection.chainId,
    })
    options.push(createNativeOptions(BigInt(20_000), parseEther(selection.valueInEther), nullAddress))
    messages.push('0x')
  }
 
  let fees: bigint[] = []
  try {
    const v2LZids = feeChains.map((feeChain) => feeChain.v2LZid)
 
    fees = (await client.readContract({
      address: '0x26DA582889f59EaaE9dA1f063bE0140CD93E6a4f',
      abi: estimateFeesAbi,
      functionName: 'estimateFees',
      args: [v2LZids, messages, options],
    })) as bigint[]
  } catch (error) {
    console.error('Read Contract Error', error)
  }
 
  const lzFees = fees.reduce((p, c) => p + c, BigInt(0))
  return lzFees
}
 
// Deposit
const createOptimizedAdapterParams = (dstChainId: bigint, nativeAmount: bigint) => {
  return (dstChainId << BigInt(224)) | nativeAmount
}
 
;(async () => {
  const lzFee = await estimateFees()
  const adapterParamsDeposit: bigint[] = []
  for (const chain in contractParams) {
    const selection = contractParams[chain]
    adapterParamsDeposit.push(
      createOptimizedAdapterParams(BigInt(selection.v2LZid), parseEther(selection.valueInEther)),
    )
  }
 
  const { request } = await client.simulateContract({
    address: '0x26DA582889f59EaaE9dA1f063bE0140CD93E6a4f',
    abi: lzDepositAbi,
    functionName: 'sendDeposits',
    value: lzFee,
    args: [adapterParamsDeposit, account.address],
  })
 
  await client.writeContract(request)
})().catch((error) => console.error(error))

export const estimateFeesAbi = [
  {
    type: 'function',
    name: 'estimateFees',
    inputs: [
      {
        name: '_dstEids',
        type: 'uint32[]',
        internalType: 'uint32[]',
      },
      {
        name: '_messages',
        type: 'bytes[]',
        internalType: 'bytes[]',
      },
      {
        name: '_options',
        type: 'bytes[]',
        internalType: 'bytes[]',
      },
    ],
    outputs: [
      {
        name: 'nativeFees',
        type: 'uint256[]',
        internalType: 'uint256[]',
      },
    ],
    stateMutability: 'view',
  },
] as const
 
export const lzDepositAbi = [
  {
    inputs: [
      {
        internalType: 'uint256[]',
        name: '_depositParams',
        type: 'uint256[]',
      },
      {
        internalType: 'address',
        name: 'to',
        type: 'address',
      },
    ],
    name: 'sendDeposits',
    outputs: [],
    stateMutability: 'payable',
    type: 'function',
  },
] as const

Example for limits

Every route combination has a specifc maximum it can send/recieve on the other side. If you exceed this amount, the contract will revert. Use the following to check what the maximum limit is on your desired destination chain.

WARNING: If a chain returns 0, that means the inbound to outbound combination is not supported and the transaction will revert. The result must be > 0.

import { createPublicClient, http } from 'viem'
import { mainnet } from 'viem/chains'
import { limitsAbi } from './abis'
 
const client = createPublicClient({
  chain: mainnet,
  transport: http(),
})
 
const lzId = 30110
 
async function getLimit(lzId: number): Promise<bigint> {
  const config = (await client.readContract({
    address: '0x90E595783E43eb89fF07f63d27B8430e6B44bD9c', // executor
    abi: limitsAbi,
    functionName: 'dstConfig',
    args: [lzId],
  })) as bigint[]
 
  return config[3]
}
 
getLimit(lzId)
  .then((limit) => {
    console.log(`The limit is: ${limit}`)
  })
  .catch((error) => console.error(error))

export const limitsAbi = [
  {
    constant: true,
    inputs: [
      {
        name: '_key1',
        type: 'uint32',
      },
    ],
    name: 'dstConfig',
    outputs: [
      {
        components: [
          {
            name: 'baseGas',
            type: 'uint64',
          },
          {
            name: 'multiplier',
            type: 'uint16',
          },
          {
            name: 'floorMarginUSD',
            type: 'uint128',
          },
          {
            name: 'nativeCap',
            type: 'uint128',
          },
        ],
        type: 'tuple',
      },
    ],
    type: 'function',
  },
]

Questions & Contact

Please feel free to ask questions in the Gas.zip Discord channel or DM us on Twitter.