From c028fbd9d24d0cc759992e1e8004e0fe958cb58f Mon Sep 17 00:00:00 2001
From: Maciej Kot <maciej.kot@dfinity.org>
Date: Mon, 15 Jan 2024 13:01:42 +0900
Subject: [PATCH] Duplicate check for send

---
 cycles-ledger/src/storage.rs | 13 ++++----
 cycles-ledger/tests/tests.rs | 64 ++++++++++++++++++++++++++++++++++++
 2 files changed, 71 insertions(+), 6 deletions(-)

diff --git a/cycles-ledger/src/storage.rs b/cycles-ledger/src/storage.rs
index 8d481a8..a5ba311 100644
--- a/cycles-ledger/src/storage.rs
+++ b/cycles-ledger/src/storage.rs
@@ -1466,6 +1466,13 @@ pub async fn send(
         return Err(InsufficientFunds { balance: balance_of(&from).into() });
     };
 
+    let transaction = Transaction {
+        operation: Operation::Burn { from, amount },
+        created_at_time,
+        memo: Some(encode_send_memo(&to)),
+    };
+    check_duplicate(&transaction)?;
+
     // check that the `from` account has enough funds
     read_state(|state| state.check_debit_from_account(&from, amount_with_fee)).map_err(
         |balance| InsufficientFunds {
@@ -1485,12 +1492,6 @@ pub async fn send(
 
     // 1. burn cycles + fee
 
-    let transaction = Transaction {
-        operation: Operation::Burn { from, amount },
-        created_at_time,
-        memo: Some(encode_send_memo(&to)),
-    };
-
     let block_index = process_block(transaction.clone(), now, Some(config::FEE))?;
 
     if let Err(err) = mutate_state(|state| state.debit(&from, amount_with_fee)) {
diff --git a/cycles-ledger/tests/tests.rs b/cycles-ledger/tests/tests.rs
index 4d0e430..40d8a54 100644
--- a/cycles-ledger/tests/tests.rs
+++ b/cycles-ledger/tests/tests.rs
@@ -318,6 +318,70 @@ fn test_send_flow() {
     assert_eq!(total_supply(env, ledger_id), expected_total_supply);
 }
 
+#[test]
+fn test_send_duplicate() {
+    let env = &new_state_machine();
+    let ledger_id = install_ledger(env);
+    let depositor_id = install_depositor(env, ledger_id);
+    let user_main_account = Account {
+        owner: Principal::from_slice(&[1]),
+        subaccount: None,
+    };
+    let send_receiver = env.create_canister(None);
+
+    // make deposits to the user and check the result
+    let deposit_res = deposit(env, depositor_id, user_main_account, 1_000_000_000);
+    assert_eq!(deposit_res.block_index, 0);
+    assert_eq!(deposit_res.balance, 1_000_000_000);
+
+    let now = env
+        .time()
+        .duration_since(SystemTime::UNIX_EPOCH)
+        .unwrap()
+        .as_nanos() as u64;
+    // send cycles from main account
+    let send_receiver_balance = env.cycle_balance(send_receiver);
+    let send_amount = 900_000_000_u128;
+    let send_idx = send(
+        env,
+        ledger_id,
+        user_main_account,
+        SendArgs {
+            from_subaccount: None,
+            to: send_receiver,
+            created_at_time: Some(now),
+            amount: Nat::from(send_amount),
+        },
+    )
+    .unwrap();
+    assert_eq!(
+        send_receiver_balance + send_amount,
+        env.cycle_balance(send_receiver)
+    );
+    assert_eq!(
+        balance_of(env, ledger_id, user_main_account),
+        1_000_000_000 - send_amount - FEE
+    );
+
+    assert_eq!(
+        SendError::Duplicate {
+            duplicate_of: send_idx
+        },
+        send(
+            env,
+            ledger_id,
+            user_main_account,
+            SendArgs {
+                from_subaccount: None,
+                to: send_receiver,
+                created_at_time: Some(now),
+                amount: Nat::from(send_amount),
+            },
+        )
+        .unwrap_err()
+    );
+}
+
 #[test]
 fn test_send_fails() {
     let env = &new_state_machine();