dexorder

lib_openzeppelin_contracts/certora/specs/ERC20FlashMint.spec

@@ -0,0 +1,55 @@
+import "helpers/helpers.spec";
+import "methods/IERC20.spec";
+import "methods/IERC3156FlashLender.spec";
+import "methods/IERC3156FlashBorrower.spec";
+
+methods {
+    // non standard ERC-3156 functions
+    function flashFeeReceiver() external returns (address) envfree;
+
+    // function summaries below
+    function _._update(address from, address to, uint256 amount) internal => specUpdate(from, to, amount) expect void ALL;
+}
+
+/*
+┌─────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┐
+│ Ghost: track mint and burns in the CVL                                                                              │
+└─────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┘
+*/
+ghost mapping(address => mathint)                     trackedMintAmount;
+ghost mapping(address => mathint)                     trackedBurnAmount;
+ghost mapping(address => mapping(address => mathint)) trackedTransferedAmount;
+
+function specUpdate(address from, address to, uint256 amount) {
+    if (from == 0 && to == 0) { assert(false); } // defensive
+
+    if (from == 0) {
+        trackedMintAmount[to] = amount;
+    } else if (to == 0) {
+        trackedBurnAmount[from] = amount;
+    } else {
+        trackedTransferedAmount[from][to] = amount;
+    }
+}
+
+/*
+┌─────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┐
+│ Rule: When doing a flashLoan, "amount" is minted and burnt, additionally, the fee is either burnt                   │
+│ (if the fee recipient is 0) or transferred (if the fee recipient is not 0)                                          │
+└─────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┘
+*/
+rule checkMintAndBurn(env e) {
+    address receiver;
+    address token;
+    uint256 amount;
+    bytes data;
+
+    uint256 fees = flashFee(token, amount);
+    address recipient = flashFeeReceiver();
+
+    flashLoan(e, receiver, token, amount, data);
+
+    assert trackedMintAmount[receiver] == to_mathint(amount);
+    assert trackedBurnAmount[receiver] == amount + to_mathint(recipient == 0 ? fees : 0);
+    assert (fees > 0 && recipient != 0) => trackedTransferedAmount[receiver][recipient] == to_mathint(fees);
+}