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feat: add Permit2
approval process for UniversalRouter
#980
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Original file line number | Diff line number | Diff line change |
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@@ -0,0 +1,5 @@ | ||
--- | ||
"@coinbase/onchainkit": minor | ||
--- | ||
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**feat**: add Permit2 approval process for UniversalRouter by @0xAlec #980 |
Original file line number | Diff line number | Diff line change |
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@@ -1,7 +1,12 @@ | ||
import type { TransactionReceipt } from 'viem'; | ||
import type { Address, TransactionReceipt } from 'viem'; | ||
import { encodeFunctionData, parseAbi } from 'viem'; | ||
import type { Config } from 'wagmi'; | ||
import { waitForTransactionReceipt } from 'wagmi/actions'; | ||
import type { SendTransactionMutateAsync } from 'wagmi/query'; | ||
import { | ||
PERMIT2_CONTRACT_ADDRESS, | ||
UNIVERSALROUTER_CONTRACT_ADDRESS, | ||
} from '../constants'; | ||
import type { BuildSwapTransaction } from '../types'; | ||
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export async function processSwapTransaction({ | ||
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@@ -12,6 +17,7 @@ export async function processSwapTransaction({ | |
sendTransactionAsync, | ||
onStart, | ||
onSuccess, | ||
useAggregator, | ||
}: { | ||
swapTransaction: BuildSwapTransaction; | ||
config: Config; | ||
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@@ -22,12 +28,15 @@ export async function processSwapTransaction({ | |
onSuccess: | ||
| ((txReceipt: TransactionReceipt) => void | Promise<void>) | ||
| undefined; | ||
useAggregator: boolean; | ||
}) { | ||
const { transaction, approveTransaction } = swapTransaction; | ||
const { transaction, approveTransaction, quote } = swapTransaction; | ||
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// for swaps from ERC-20 tokens, | ||
// if there is an approveTransaction present, | ||
// request approval for the amount | ||
// for V1 API, `approveTx` will be an ERC-20 approval against the Router | ||
// for V2 API, `approveTx` will be an ERC-20 approval against the `Permit2` contract | ||
if (approveTransaction?.data) { | ||
setPendingTransaction(true); | ||
const approveTxHash = await sendTransactionAsync({ | ||
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@@ -41,6 +50,39 @@ export async function processSwapTransaction({ | |
confirmations: 1, | ||
}); | ||
setPendingTransaction(false); | ||
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// for the V2 API, we use Uniswap's `UniversalRouter`, which uses `Permit2` for ERC-20 approvals | ||
// this adds an additional transaction/step to the swap process | ||
// since we need to make an extra transaction to `Permit2` to allow the UniversalRouter to spend the approved funds | ||
// this would typically be a (gasless) signature, but we're using a transaction here to allow batching for Smart Wallets | ||
// read more: https://blog.uniswap.org/permit2-and-universal-router | ||
if (!useAggregator) { | ||
There was a problem hiding this comment. Choose a reason for hiding this commentThe reason will be displayed to describe this comment to others. Learn more. I feel like this code, has a lot of important pieces, and there is only one unit-test checking on this. I wonder how this could be break down in 2~3 unit-tests. Or even the code break down a bit more. There was a problem hiding this comment. Choose a reason for hiding this commentThe reason will be displayed to describe this comment to others. Learn more. the single unit test checks for all of the code/cases in this conditional
there can be an argument to decompose into two separate functions - |
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setPendingTransaction(true); | ||
const permit2ContractAbi = parseAbi([ | ||
'function approve(address token, address spender, uint160 amount, uint48 expiration) external', | ||
]); | ||
const data = encodeFunctionData({ | ||
abi: permit2ContractAbi, | ||
functionName: 'approve', | ||
args: [ | ||
quote.from.address as Address, | ||
UNIVERSALROUTER_CONTRACT_ADDRESS, | ||
BigInt(quote.fromAmount), | ||
20_000_000_000_000, | ||
There was a problem hiding this comment. Choose a reason for hiding this commentThe reason will be displayed to describe this comment to others. Learn more. Why this number? what's the meaning behind. There was a problem hiding this comment. Choose a reason for hiding this commentThe reason will be displayed to describe this comment to others. Learn more. https://docs.uniswap.org/contracts/permit2/reference/allowance-transfer it's the deadline where the approval is no longer valid - since we're only approving the exact amount There was a problem hiding this comment. Choose a reason for hiding this commentThe reason will be displayed to describe this comment to others. Learn more. I feel like we should either have a comment here, or have a variable that better explain what's for. This will help future developer undersand what's going on. There was a problem hiding this comment. Choose a reason for hiding this commentThe reason will be displayed to describe this comment to others. Learn more. added a comment with a link to the above |
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], | ||
}); | ||
const permitTxnHash = await sendTransactionAsync({ | ||
to: PERMIT2_CONTRACT_ADDRESS, | ||
data: data, | ||
value: 0n, | ||
}); | ||
await Promise.resolve(onStart?.(permitTxnHash)); | ||
await waitForTransactionReceipt(config, { | ||
hash: permitTxnHash, | ||
confirmations: 1, | ||
}); | ||
setPendingTransaction(false); | ||
} | ||
} | ||
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// make the swap | ||
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Why
minor
? is this causing a breaking changes?There was a problem hiding this comment.
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it will be a breaking change for users of
V2 API
- but it is underexperimental
flag anyways so developers probably understand there will be breaking changesi can change this to
patch
if you think it's more suitableThere was a problem hiding this comment.
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let's do
patch
as it is experimental.There was a problem hiding this comment.
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fixed