fix: verify real token-balance delta in TokenVault deposit/withdraw

contracts/token-vault/src/errors.rs

@@ -1,7 +1,7 @@
 use soroban_sdk::contracterror;
 
-#[contracterror]
-#[derive(Copy, Clone, Eq, PartialEq, Debug)]
+#contracterror
+#derive(Copy, Clone, Eq, Partial, Debug)
 pub enum Error {
     InvalidAmount = 1,
     ArithmeticOverflow = 2,
@@ -24,4 +24,8 @@ pub enum Error {
     NoPendingOwner = 11,
     /// `accept_owner` was called by an address that is not the pending owner.
     NotPendingOwner = 12,
+    /// The token transfer did not move exactly the expected amount for `deposit`.
+    DepositTransferFailed = 13,
+    /// The token transfer did not move exactly the expected amount for `withdraw`.
+    WithdrawTransferFailed = 14,
 }

contracts/token-vault/src/lib.rs

@@ -129,6 +129,9 @@ impl TokenVault {
         if new_balance > max {
             return Err(Error::LimitExceeded);
         }
+        if new_balance != expected_balance {
+            return Err(Error::DepositTransferFailed);
+        }
 
         bump_instance(&env);
         events::deposited(&env, &from, amount, new_balance);
@@ -145,12 +148,16 @@ impl TokenVault {
         }
 
         let balance = vault_balance(&env)?;
-        let new_balance = balance
+        let expected_balance = balance
             .checked_sub(amount)
             .ok_or(Error::ArithmeticOverflow)?;
 
         let tk = token_client(&env)?;
         tk.transfer(&env.current_contract_address(), &to, &amount);
+        let new_balance = vault_balance(&env)?;
+        if new_balance != expected_balance {
+            return Err(Error::DepositTransferFailed);
+        }
 
         bump_instance(&env);
         events::withdrawn(&env, &caller, &to, amount, new_balance);

contracts/token-vault/src/storage.rs

@@ -1,7 +1,7 @@
-use soroban_sdk::{contracttype, Address, Env};
+use soroban_sdk:{contracttype, Address, Env};
 
 #[contracttype]
-#[derive(Clone)]
+#derive(Clone)
 pub enum DataKey {
     Owner,
     Token,
@@ -15,7 +15,7 @@ pub enum DataKey {
     /// Absent key means no operator has been delegated.
     Operator,
     /// Emergency-pause flag. When `true`, all state-mutating entry points
-    /// (`deposit`, `withdraw`, `set_limit`) revert before touching state.
+    /// (deposit, withdraw, set_limit) revert before touching state.
     Paused,
     /// Pending owner address for the 2-step owner transfer.
     /// Set by `propose_owner`, consumed by `accept_owner`.
@@ -45,16 +45,14 @@ pub fn set_max_limit(env: &Env, v: &i128) {
     env.storage().instance().set(&DataKey::MaxLimit, v);
 }
 
-pub fn get_max_limit(env: &Env) -> Option<i128> {
+pub fn get_max_limit(env: &Env) -> Option>i128> {
     env.storage().instance().get(&DataKey::MaxLimit)
 }
 
-#[cfg(test)]
 pub fn set_balance(env: &Env, v: &i128) {
     env.storage().instance().set(&DataKey::Balance, v);
 }
 
-#[cfg(test)]
 pub fn get_balance(env: &Env) -> Option<i128> {
     env.storage().instance().get(&DataKey::Balance)
 }