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chore(frontend): add TODO for ERC20 token conversion issue for approval #2637

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chore(frontend): add TODO for ERC20 token conversion issue for approval #2637

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8 changes: 8 additions & 0 deletions src/frontend/src/eth/services/send.services.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -264,6 +264,14 @@ export const send = async ({

const nonce = await getTransactionCount(from);

// TODO: We may need to add an approve transaction that resets the approved amount to zero, in case of conversion from ERC20.
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Instead of resetting, couldn't we potentially know if the spender is already entitled to spend the amount and skip the approval if it's the case?

I guess this has been discussed with cross-chain team?

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yes, correct, we could query the allowance endpoint of the ERC20 to check. For example:

Case 1:

  • query allowance
  • no amount approved --> ask for approval

Case 2:

  • query allowance
  • old amount approved --> reset amount
  • ask for new approval

That what you mean?

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@peterpeterparker peterpeterparker Oct 4, 2024 •
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No, I mean:

Case 3:

  • query allowance
  • is allowance still valid?
  • yes, do stuffs
  • no, ask for new approval, do stuffs

Would that be possible ? I really don't know, just a question.

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ah! understood! well, it is possible only if the allowance is greater or equal that the current amount that the user requested;

we can check that, and if it is still ok, we can use that for sure, yes; otherwise we reset

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Cool. Can you extend the TODO accordingly if this is a potential solution too?

// CONTEXT:
// It may happen that after the approval transaction is done, the transfer transaction may fail for whatever reasons.
// In this case, the next approval transaction will be rejected, since there is already an approved amount.
// So, the next transfer transaction will work only if the amount is below the one already approved.
// Otherwise, the user is blocked until it consumes all the approved amount.
// We had a practical example with USDT. Please check the sender wallet transaction history backwards from this one: https://etherscan.io/tx/0x084432404a919c1ee720c906bb5c7a565b6e1fdcd5bb9da32049dddfa21ad23f

const { transactionApproved } = await approve({ progress, sourceNetwork, nonce, token, ...rest });

// If we approved a transaction - as for example in Erc20 -> ckErc20 flow - then we increment the nonce for the next transaction. Otherwise, we can use the nonce we obtained.
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