@cowprotocol/许可证使用

收集用于处理象征性许可的提款机.

安装

npm install @cowprotocol/permit-utils

使用量

getTokenPermitInfo

import { getTokenPermitInfo } from "@cowprotocol/permit-utils"

const permitInfo = await getTokenPermitInfo({
  spender, tokenAddress, tokenName, chainId, provider
})

getPermitUtilsInstance

import { getPermitUtilsInstance } from "@cowprotocol/permit-utils"

// Using a static account defined in the library
const staticEip2612PermitUtils = await getPermitUtilsInstance(chainId, provider)

// Using a provided account address
const accountEip2612PermitUtils = await getPermitUtilsInstance(chainId, provider, account)

generatePermitHook

import { generatePermitHook } from "@cowprotocol/permit-utils"

const hookData = await generatePermitHook({
  chainId,
  inputToken,
  spender,
  provider,
  permitInfo,
  eip2612Utils,
  account,
  nonce
})

checkIsCallDataAValidPermit

import { checkIsCallDataAValidPermit } from "@cowprotocol/permit-utils"

const isCallDataAValidPermit = await checkIsCallDataAValidPermit(
  account,
  chainId,
  eip2612Utils,
  tokenAddress,
  tokenName,
  callData,
  permitInfo
)

全流程示例

说明一下,我们将展示使用这种液态的电动装置,用许可钩下订单的流程.

1. 检查给定的令牌是否是许可表
2. 如果是的话, 生成一个许可钩
3. 添加许可钩子以订购 appData
4. 定期检查许可证是否仍然有效

import { checkIsCallDataAValidPermit, generatePermitHook, getPermitUtilsInstance, getTokenPermitInfo } from '@cowprotocol/permit-utils'
import { stringifyDeterministic, OrderBookApi } from '@cowprotocol/cow-sdk'


// Check whether token is permittable.
// No account info is necessary.
// `spender` could in theory be any address
// `tokenName` must always match the contract
const permitInfo = await getTokenPermitInfo({
  spender, tokenAddress, tokenName, chainId, provider
})

// Not able to tell or not permittable
if (!permitInfo) {
  return
}

// Pass in an account address as we'll need the user to sign the actual permit
const eip2612Utils = await getPermitUtilsInstance(chainId, provider, account)

// Need to know what the current permit nonce is
const nonce = await eip2612Utils.getTokenNonce(inputToken.address, account)

// Calling this fn should trigger the signature in the user's wallet
const hookData = await generatePermitHook({
  chainId,
  inputToken,
  spender, // Now `spender` must be the real one
  provider,
  permitInfo,
  eip2612Utils,
  account, // `account` should also be the user's
  nonce
})

// Add the hookData to the order's appData
// See the full reference on https://www.npmjs.com/package/@cowprotocol/sdk-app-data?activeTab=code
const appData = { version: '0.10.0', metadata: { hooks: { pre: [hookData] } } }

// The order expects the stringified JSON doc
const fullAppData = await stringifyDeterministic(appData)

// Build cow-sdk orderBookApi instance
const orderBookApi = new OrderBookApi()

// Note: price quoting is a required step before placing the order but has been left out of this example for brevity

// Place order
const orderId = await orderBookApi.sendOrder(
  {
    ...orderParameters,
    quoteId, // Must be fetched before hand, and also include the appData in the params
    appData: fullAppData // <-- The order will be placed with the permit info
  },
  { chainId }
)

// Now we check whether the permit included in the order is still valid
// It'll become invalid when another permit is executed
// This check does not consider whether the `address` has enough allowance, it purelly checks the permit validity.

// CallData is part of the hookData
const callData = hookData.callData

// All properties must match what was used when the hookData was generated
const isCallDataAValidPermit = await checkIsCallDataAValidPermit(
  account,
  chainId,
  eip2612Utils,
  tokenAddress,
  tokenName,
  callData,
  permitInfo
)