feat(ckerc20): support subaccounts for ckERC20 withdrawals (#2510)

Allow a user to specify two optional ledger subaccounts when withdrawing
ckERC20:

1. one on the ckETH ledger to pay for the transaction fee
2. on the ckERC20 ledger where the tokens are being withdrawn.

rs/ethereum/cketh/minter/cketh_minter.did

@@ -362,6 +362,12 @@ type WithdrawErc20Arg = record {
 
     // Ethereum address to withdraw to.
     recipient : text;
+
+    // The subaccount to burn ckETH from to pay for the transaction fee.
+    from_cketh_subaccount : opt Subaccount;
+
+    // The subaccount to burn ckERC20 from.
+    from_ckerc20_subaccount : opt Subaccount;
 };
 
 type RetrieveErc20Request = record {

rs/ethereum/cketh/minter/src/endpoints/ckerc20.rs

@@ -1,12 +1,15 @@
 use crate::ledger_client::LedgerBurnError;
 use crate::state::transactions::Erc20WithdrawalRequest;
 use candid::{CandidType, Deserialize, Nat, Principal};
+use icrc_ledger_types::icrc1::account::Subaccount;
 
 #[derive(CandidType, Deserialize)]
 pub struct WithdrawErc20Arg {
     pub amount: Nat,
     pub ckerc20_ledger_id: Principal,
     pub recipient: String,
+    pub from_cketh_subaccount: Option<Subaccount>,
+    pub from_ckerc20_subaccount: Option<Subaccount>,
 }
 
 #[derive(Clone, PartialEq, Debug, CandidType, Deserialize)]

rs/ethereum/cketh/minter/src/main.rs

@@ -399,6 +399,8 @@ async fn withdraw_erc20(
         amount,
         ckerc20_ledger_id,
         recipient,
+        from_cketh_subaccount,
+        from_ckerc20_subaccount,
     }: WithdrawErc20Arg,
 ) -> Result<RetrieveErc20Request, WithdrawErc20Error> {
     validate_ckerc20_active();
@@ -436,11 +438,24 @@ async fn withdraw_erc20(
     let erc20_tx_fee = estimate_erc20_transaction_fee().await.ok_or_else(|| {
         WithdrawErc20Error::TemporarilyUnavailable("Failed to retrieve current gas fee".to_string())
     })?;
+    let cketh_account = Account {
+        owner: caller,
+        subaccount: from_cketh_subaccount,
+    };
+    let ckerc20_account = Account {
+        owner: caller,
+        subaccount: from_ckerc20_subaccount,
+    };
     let now = ic_cdk::api::time();
-    log!(INFO, "[withdraw_erc20]: burning {:?} ckETH", erc20_tx_fee);
+    log!(
+        INFO,
+        "[withdraw_erc20]: burning {:?} ckETH from account {}",
+        erc20_tx_fee,
+        cketh_account
+    );
     match cketh_ledger
         .burn_from(
-            caller.into(),
+            cketh_account,
             erc20_tx_fee,
             BurnMemo::Erc20GasFee {
                 ckerc20_token_symbol: ckerc20_token.ckerc20_token_symbol.clone(),
@@ -453,13 +468,14 @@ async fn withdraw_erc20(
         Ok(cketh_ledger_burn_index) => {
             log!(
                 INFO,
-                "[withdraw_erc20]: burning {} {}",
+                "[withdraw_erc20]: burning {} {} from account {}",
                 ckerc20_withdrawal_amount,
-                ckerc20_token.ckerc20_token_symbol
+                ckerc20_token.ckerc20_token_symbol,
+                ckerc20_account
             );
             match LedgerClient::ckerc20_ledger(&ckerc20_token)
                 .burn_from(
-                    caller.into(),
+                    ckerc20_account,
                     ckerc20_withdrawal_amount,
                     BurnMemo::Erc20Convert {
                         ckerc20_withdrawal_id: cketh_ledger_burn_index.get(),
@@ -478,7 +494,8 @@ async fn withdraw_erc20(
                         ckerc20_ledger_burn_index,
                         erc20_contract_address: ckerc20_token.erc20_contract_address,
                         from: caller,
-                        from_subaccount: None,
+                        from_subaccount: from_ckerc20_subaccount
+                            .and_then(LedgerSubaccount::from_bytes),
                         created_at: now,
                     };
                     log!(
@@ -507,8 +524,10 @@ async fn withdraw_erc20(
                         let reimbursement_request = ReimbursementRequest {
                             ledger_burn_index: cketh_ledger_burn_index,
                             reimbursed_amount: reimbursed_amount.change_units(),
-                            to: caller,
-                            to_subaccount: None,
+                            to: cketh_account.owner,
+                            to_subaccount: cketh_account
+                                .subaccount
+                                .and_then(LedgerSubaccount::from_bytes),
                             transaction_hash: None,
                         };
                         mutate_state(|s| {