Merge pull request #8 from EspressoSystems/jh/fraud

Update hotshot contract interface

src/bridge/IHotShot.sol

@@ -0,0 +1,15 @@
+// SPDX-License-Identifier: BUSL-1.1
+pragma solidity ^0.8.0;
+
+struct HotShotCommitment {
+    uint64 blockHeight;
+    uint256 blockCommRoot;
+}
+
+interface IHotShot {
+    function getHotShotCommitment(uint256 hotShotBlockHeight) external view returns (HotShotCommitment memory);
+    function lagOverEscapeHatchThreshold(
+        uint256 blockNumber,
+        uint256 threshold
+    ) external view returns (bool);
+}

src/osp/OneStepProverHostIo.sol

@@ -13,11 +13,7 @@ import "../state/ModuleMemory.sol";
 import "./IOneStepProver.sol";
 import "../bridge/Messages.sol";
 import "../bridge/IBridge.sol";
-
-interface IHotShot {
-    function commitments(uint256) external view returns (uint256);
-    function availabilities(uint256) external view returns (bool);
-}
+import "../bridge/IHotShot.sol";
 
 contract OneStepProverHostIo is IOneStepProver {
     using GlobalStateLib for GlobalState;
@@ -40,6 +36,10 @@ contract OneStepProverHostIo is IOneStepProver {
     uint64 private constant INBOX_HEADER_LEN = 40;
     uint64 private constant DELAYED_HEADER_LEN = 112 + 1;
 
+    // Hard coded for now. Find out a way to access the arb config
+    // in this contract and move this constant into the configuration.
+    uint256 private constant ESPRESSO_ESCAPE_HATCH_DELAY_THRESHOLD = 3;
+
     function setLeafByte(
         bytes32 oldLeaf,
         uint256 idx,
@@ -55,7 +55,7 @@ contract OneStepProverHostIo is IOneStepProver {
     }
 
     function _getHotShotCommitment(uint256 h) external view returns (uint256) {
-        return hotshot.commitments(h);
+        return hotshot.getHotShotCommitment(h).blockCommRoot;
     }
 
     function executeGetOrSetBytes32(
@@ -323,17 +323,19 @@ contract OneStepProverHostIo is IOneStepProver {
         bytes calldata proof
     ) internal view {
         uint256 height = mach.valueStack.pop().assumeI64();
+        uint256 threshold = ESPRESSO_ESCAPE_HATCH_DELAY_THRESHOLD;
         uint8 liveness = uint8(proof[0]);
-        require(validateHotShotLiveness(execCtx, height, liveness > 0), "WRONG_HOTSHOT_LIVENESS");
+        require(validateHotShotLiveness(execCtx, height, threshold, liveness > 0), "WRONG_HOTSHOT_LIVENESS");
 
     }
 
     function validateHotShotLiveness(
         ExecutionContext calldata,
         uint256 height,
+        uint256 threshold,
         bool result
     ) internal view returns (bool) {
-        bool expected = hotshot.availabilities(height);
+        bool expected = hotshot.lagOverEscapeHatchThreshold(height, threshold);
         return result == expected;
     }
 
@@ -378,7 +380,7 @@ contract OneStepProverHostIo is IOneStepProver {
         uint256 height,
         bytes calldata commitment
     ) internal view returns (bool) {
-        uint256 expected = hotshot.commitments(height);
+        uint256 expected = hotshot.getHotShotCommitment(height).blockCommRoot;
         require(expected != 0, "EMPTY HOTSHOT COMMITMENT");
         bytes memory b = new bytes(32);
         assembly {

src/test-helpers/HotShot.sol

@@ -1,15 +1,38 @@
 // SPDX-License-Identifier: BUSL-1.1
 pragma solidity ^0.8.0;
 
-contract MockHotShot {
+import "../bridge/IHotShot.sol";
+
+contract MockHotShot is IHotShot {
     mapping(uint256 => uint256) public commitments;
-    mapping(uint256 => bool) public availabilities;
+    mapping(uint256 => bool) public livenesses;
+
+    function getHotShotCommitment(uint256 hotShotBlockHeight)
+        external
+        view
+        override
+        returns (HotShotCommitment memory)
+    {
+        return HotShotCommitment({
+            blockHeight: uint64(hotShotBlockHeight),
+            blockCommRoot: commitments[hotShotBlockHeight]
+        });
+    }
+
+    function lagOverEscapeHatchThreshold(uint256 blockNumber, uint256 threshold)
+        external
+        view
+        override
+        returns (bool)
+    {
+        return true;
+    }
 
     function setCommitment(uint256 height, uint256 commitment) external {
         commitments[height] = commitment;
     }
 
-    function setAvailability(uint256 l1Height, bool isLive) external {
-        availabilities[l1Height] = isLive;
+    function setLiveness(uint256 l1Height, bool isLive) external {
+        livenesses[l1Height] = isLive;
     }
 }