chore(contracts/core): allow bridge fee overpayment

contracts/core/.gas-snapshot

@@ -1,8 +1,8 @@
-Admin_Test:test_pause_unpause() (gas: 26104285)
-Admin_Test:test_pause_unpause_bridge() (gas: 21279753)
-Admin_Test:test_pause_unpause_xcall() (gas: 26058227)
-Admin_Test:test_pause_unpause_xsubmit() (gas: 26057978)
-Admin_Test:test_upgrade() (gas: 29993873)
+Admin_Test:test_pause_unpause() (gas: 26108503)
+Admin_Test:test_pause_unpause_bridge() (gas: 21283971)
+Admin_Test:test_pause_unpause_xcall() (gas: 26062445)
+Admin_Test:test_pause_unpause_xsubmit() (gas: 26062196)
+Admin_Test:test_upgrade() (gas: 29998091)
 AllocPredeploys_Test:test_num_allocs() (gas: 1181021629)
 AllocPredeploys_Test:test_predeploys() (gas: 1180958103)
 AllocPredeploys_Test:test_preinstalls() (gas: 1181593197)
@@ -24,13 +24,13 @@ FeeOracleV2_Test:test_setProtocolFee() (gas: 31508)
 FeeOracleV2_Test:test_setToNativeRate() (gas: 43377)
 InitializableHelper_Test:test_disableInitalizers() (gas: 181686)
 InitializableHelper_Test:test_getInitialized() (gas: 178023)
-OmniBridgeL1_Test:test_bridge() (gas: 252423)
+OmniBridgeL1_Test:test_bridge() (gas: 233678)
 OmniBridgeL1_Test:test_pauseAll() (gas: 49368)
-OmniBridgeL1_Test:test_pauseBridging() (gas: 59610)
+OmniBridgeL1_Test:test_pauseBridging() (gas: 59580)
 OmniBridgeL1_Test:test_pauseWithdraws() (gas: 48975)
 OmniBridgeL1_Test:test_stub() (gas: 143)
-OmniBridgeL1_Test:test_withdraw() (gas: 1382984)
-OmniBridgeNative_Test:test_bridge() (gas: 190446)
+OmniBridgeL1_Test:test_withdraw() (gas: 1386987)
+OmniBridgeNative_Test:test_bridge() (gas: 156805)
 OmniBridgeNative_Test:test_claim() (gas: 287756)
 OmniBridgeNative_Test:test_pauseAll() (gas: 52904)
 OmniBridgeNative_Test:test_pauseBridging() (gas: 44449)

contracts/core/src/token/OmniBridgeL1.sol

@@ -85,7 +85,9 @@ contract OmniBridgeL1 is OmniBridgeCommon {
         bytes memory xcalldata =
             abi.encodeCall(OmniBridgeNative.withdraw, (payor, to, amount, token.balanceOf(address(this)) + amount));
 
-        require(msg.value == omni.feeFor(omniChainId, xcalldata, XCALL_WITHDRAW_GAS_LIMIT), "OmniBridge: incorrect fee");
+        require(
+            msg.value >= omni.feeFor(omniChainId, xcalldata, XCALL_WITHDRAW_GAS_LIMIT), "OmniBridge: insufficient fee"
+        );
         require(token.transferFrom(payor, address(this), amount), "OmniBridge: transfer failed");
 
         omni.xcall{ value: msg.value }(

contracts/core/src/token/OmniBridgeNative.sol

@@ -125,13 +125,13 @@ contract OmniBridgeNative is OmniBridgeCommon {
         require(to != address(0), "OmniBridge: no bridge to zero");
         require(amount > 0, "OmniBridge: amount must be > 0");
         require(amount <= l1BridgeBalance, "OmniBridge: no liquidity");
-
-        uint256 fee = bridgeFee(to, amount);
-        require(msg.value == amount + fee, "OmniBridge: incorrect funds");
+        require(msg.value >= amount + bridgeFee(to, amount), "OmniBridge: insufficient funds");
 
         l1BridgeBalance -= amount;
 
-        omni.xcall{ value: fee }(
+        // if fee is overpaid, forward excess to portal.
+        // balance of this contract should continue to reflect funds bridged to L1.
+        omni.xcall{ value: msg.value - amount }(
             l1ChainId,
             ConfLevel.Finalized,
             l1Bridge,

contracts/core/test/token/OmniBridgeL1.t.sol

@@ -62,10 +62,8 @@ contract OmniBridgeL1_Test is Test {
         vm.expectRevert("OmniBridge: no bridge to zero");
         b.bridge(address(0), amount);
 
-        // value must equal fee
-        vm.expectRevert("OmniBridge: incorrect fee");
-        b.bridge{ value: fee + 1 }(to, amount);
-        vm.expectRevert("OmniBridge: incorrect fee");
+        // value must be greater than or equal fee
+        vm.expectRevert("OmniBridge: insufficient fee");
         b.bridge{ value: fee - 1 }(to, amount);
 
         // requires allowance
@@ -191,8 +189,8 @@ contract OmniBridgeL1_Test is Test {
         // assert unpaused
         assertFalse(b.isPaused(action));
 
-        // bridge succeeds
-        vm.expectRevert("OmniBridge: incorrect fee");
+        // bridge not paused (reverts, but not due to pause)
+        vm.expectRevert("OmniBridge: insufficient fee");
         b.bridge(to, amount);
     }
 

contracts/core/test/token/OmniBridgeNative.t.sol

@@ -74,15 +74,9 @@ contract OmniBridgeNative_Test is Test {
 
         b.setL1BridgeBalance(amount);
 
-        // requires msg.value == fee + amount
-        vm.expectRevert("OmniBridge: incorrect funds");
-        b.bridge{ value: amount }(to, amount);
-        vm.expectRevert("OmniBridge: incorrect funds");
-        b.bridge{ value: amount + 1 }(to, amount);
-
-        // must equal amount + fee
-        vm.expectRevert("OmniBridge: incorrect funds");
-        b.bridge{ value: amount + fee + 1 }(to, amount);
+        // requires msg.value >= fee + amount
+        vm.expectRevert("OmniBridge: insufficient funds");
+        b.bridge{ value: amount + fee - 1 }(to, amount);
 
         // succeeds
         //
@@ -92,9 +86,10 @@ contract OmniBridgeNative_Test is Test {
         emit Bridge(address(this), to, amount);
 
         // emits xcall
+        uint256 feeWithExcess = fee + 1; // test that bridge forwards excess fee to portal
         vm.expectCall(
             address(portal),
-            fee,
+            feeWithExcess,
             abi.encodeCall(
                 IOmniPortal.xcall,
                 (
@@ -106,7 +101,7 @@ contract OmniBridgeNative_Test is Test {
                 )
             )
         );
-        b.bridge{ value: amount + fee }(to, amount);
+        b.bridge{ value: amount + feeWithExcess }(to, amount);
 
         // decrements l1BridgeBalance
         assertEq(b.l1BridgeBalance(), 0);