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| // Fetch the grandparent clock, if it exists. | ||
| // The grandparent clock should always exist unless the parent is the root claim. | ||
| Clock grandparentClock; |
Check warning
Code scanning / Slither
Uninitialized local variables
Comment on lines
+810
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| function stepV2( | ||
| uint256 _claimIndex, | ||
| uint64 _attackBranch, | ||
| bytes calldata _stateData, | ||
| bytes calldata _proof | ||
| ) | ||
| public | ||
| virtual | ||
| { | ||
| // INVARIANT: Steps cannot be made unless the game is currently in progress. | ||
| if (status != GameStatus.IN_PROGRESS) revert GameNotInProgress(); | ||
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| // Get the parent. If it does not exist, the call will revert with OOB. | ||
| ClaimData storage parent = claimData[_claimIndex]; | ||
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| // Pull the parent position out of storage. | ||
| Position parentPos = parent.position; | ||
| // Determine the position of the step. | ||
| Position stepPos = parentPos.moveN(nBits, _attackBranch); | ||
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| // INVARIANT: A step cannot be made unless the move position is 1 below the `MAX_GAME_DEPTH` | ||
| if (stepPos.depth() != MAX_GAME_DEPTH + nBits) revert InvalidParent(); | ||
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| // Determine the expected pre & post states of the step. | ||
| Claim preStateClaim; | ||
| Position preStatePosition; | ||
| Claim postStateClaim; | ||
| Position postStatePosition; | ||
| //ClaimData storage postState; | ||
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| // TODO: deal with SPLIT_DEPTH | ||
| (preStatePosition, preStateClaim) = findPreStateClaim(1 << nBits, stepPos, _claimIndex); | ||
| //(preStatePosition, preStateClaim) = findPreStateClaim(1 << nBits, parentPos, _claimIndex); | ||
| (postStatePosition, postStateClaim) = findPostStateClaim(1 << nBits, stepPos, _claimIndex); | ||
| //(postStatePosition, postStateClaim) = findPostStateClaim(1 << nBits, parentPos, _claimIndex); | ||
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| // INVARIANT: The prestate is always invalid if the passed `_stateData` is not the | ||
| // preimage of the prestate claim hash. | ||
| // We ignore the highest order byte of the digest because it is used to | ||
| // indicate the VM Status and is added after the digest is computed. | ||
| if (keccak256(_stateData) << 8 != preStateClaim.raw() << 8) revert InvalidPrestate(); | ||
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| // Compute the local preimage context for the step. | ||
| Hash uuid = _findLocalContext(_claimIndex); | ||
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| // INVARIANT: If a step is an attack, the poststate is valid if the step produces | ||
| // the same poststate hash as the parent claim's value. | ||
| // If a step is a defense: | ||
| // 1. If the parent claim and the found post state agree with each other | ||
| // (depth diff % 2 == 0), the step is valid if it produces the same | ||
| // state hash as the post state's claim. | ||
| // 2. If the parent claim and the found post state disagree with each other | ||
| // (depth diff % 2 != 0), the parent cannot be countered unless the step | ||
| // produces the same state hash as `postState.claim`. | ||
| // SAFETY: While the `attack` path does not need an extra check for the post | ||
| // state's depth in relation to the parent, we don't need another | ||
| // branch because (n - n) % 2 == 0. | ||
| bool validStep = VM.step(_stateData, _proof, uuid.raw()) == postStateClaim.raw(); | ||
| bool parentPostAgree = (parentPos.depth() - postStatePosition.depth()) % 2 == 0; | ||
| if (parentPostAgree == validStep) revert ValidStep(); | ||
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| // INVARIANT: A step cannot be made against a claim for a second time. | ||
| if (parent.counteredBy != address(0)) revert DuplicateStep(); | ||
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| // Set the parent claim as countered. We do not need to append a new claim to the game; | ||
| // instead, we can just set the existing parent as countered. | ||
| parent.counteredBy = msg.sender; | ||
| } |
Check warning
Code scanning / Slither
Reentrancy vulnerabilities
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