Neighbor root histories

contracts/anchors/bridged/AnchorPoseidon2.sol

@@ -38,16 +38,20 @@ abstract contract AnchorPoseidon2 is MerkleTreePoseidon, ReentrancyGuard {
   mapping(uint256 => bool) public edgeExistsForChain;
   Edge[] public edgeList;
 
+  // map to store chainID => (rootIndex => root) to track neighbor histories
+  mapping(uint256 => mapping(uint32 => bytes32)) public neighborRoots;
+  // map to store the current historical root index for a chainID
+  mapping(uint256 => uint32) public currentNeighborRootIndex;
+
   // map to store used nullifier hashes
   mapping(bytes32 => bool) public nullifierHashes;
   // map to store all commitments to prevent accidental deposits with the same commitment
   mapping(bytes32 => bool) public commitments;
 
   // map to store the history of root updates
   mapping(uint => bytes32[]) public rootHistory;
-  // pruning length for root history (i.e. the # of history items to persist)
-  uint pruningLength;
-  // the latest history index that represents the next index to store history at % pruningLength
+
+  // the latest history index that represents the next index to store history
   uint latestHistoryIndex;
 
   // currency events
@@ -77,8 +81,6 @@ abstract contract AnchorPoseidon2 is MerkleTreePoseidon, ReentrancyGuard {
     verifier = _verifier;
     denomination = _denomination;
     chainID = _chainID;
-    // TODO: Handle pruning length in function signature
-    pruningLength = 100;
     latestHistoryIndex = 0;
     // TODO: Parameterize max roots (length of array should be max roots)
     rootHistory[latestHistoryIndex] = new bytes32[](1);
@@ -111,37 +113,34 @@ abstract contract AnchorPoseidon2 is MerkleTreePoseidon, ReentrancyGuard {
   */
   function withdraw(
     bytes calldata _proof,
-    bytes32 _root,
+    bytes calldata _roots,
     bytes32 _nullifierHash,
     address payable _recipient,
     address payable _relayer,
     uint256 _fee,
     uint256 _refund
   ) external payable nonReentrant {
+    bytes32[2] memory roots = abi.decode(_roots, (bytes32[2]));
     require(_fee <= denomination, "Fee exceeds transfer value");
     require(!nullifierHashes[_nullifierHash], "The note has been already spent");
-    require(isKnownRoot(_root), "Cannot find your merkle root"); // Make sure to use a recent one
+    require(isKnownRoot(roots[0]), "Cannot find your merkle root");
+    require(roots.length >= edgeList.length + 1, "Incorrect root array length");
+    for (uint i = 0; i < edgeList.length; i++) {
+      Edge memory _edge = edgeList[i];
+      require(isKnownNeighborRoot(_edge.chainID, roots[i+1]), "Neighbor root not found");
+    }
     address rec = address(_recipient);
     address rel = address(_relayer);
-    bytes32[1] memory neighbors = getLatestNeighborRoots();
-    // console.log(uint256(_nullifierHash));
-    // console.log(uint256(uint160(rec)));
-    // console.log(uint256(uint160(rel)));
-    // console.log(_fee);
-    // console.log(_refund);
-    // console.log(uint256(chainID));
-    // console.log(uint256(_root));
-    // console.log(uint256(neighbors[0]));
-    // console.logBytes(_proof);
+
     uint256[8] memory inputs;
     inputs[0] = uint256(_nullifierHash);
     inputs[1] = uint256(uint160(rec));
     inputs[2] = uint256(uint160(rel));
     inputs[3] = uint256(_fee);
     inputs[4] = uint256(_refund);
     inputs[5] = uint256(chainID);
-    inputs[6] = uint256(_root);
-    inputs[7] = uint256(neighbors[0]);
+    inputs[6] = uint256(roots[0]);
+    inputs[7] = uint256(roots[1]);
     bytes memory encodedInputs = abi.encodePacked(inputs);
 
     require(verify(_proof, encodedInputs), "Invalid withdraw proof");
@@ -213,6 +212,7 @@ abstract contract AnchorPoseidon2 is MerkleTreePoseidon, ReentrancyGuard {
       }
     }
   }
+
   /** @dev */
   function getLatestNeighborRoots() public view returns (bytes32[1] memory roots) {
     for (uint256 i = 0; i < 1; i++) {
@@ -224,6 +224,25 @@ abstract contract AnchorPoseidon2 is MerkleTreePoseidon, ReentrancyGuard {
     }
   }
 
+  /** @dev */
+  function isKnownNeighborRoot(uint256 neighborChainID, bytes32 _root) public view returns (bool) {
+    if (_root == 0) {
+      return false;
+    }
+    uint32 _currentRootIndex = currentNeighborRootIndex[neighborChainID];
+    uint32 i = _currentRootIndex;
+    do {
+      if (_root == neighborRoots[neighborChainID][i]) {
+        return true;
+      }
+      if (i == 0) {
+        i = ROOT_HISTORY_SIZE;
+      }
+      i--;
+    } while (i != _currentRootIndex);
+    return false;
+  }
+
   modifier onlyAdmin()  {
     require(msg.sender == admin, 'sender is not the admin');
     _;

contracts/anchors/bridged/LinkableAnchorPoseidon2.sol

@@ -35,15 +35,6 @@ abstract contract LinkableAnchorPoseidon2 is AnchorPoseidon2, ILinkableAnchor {
     return edgeExistsForChain[_chainID];
   }
 
-  function recordHistory() override external {
-    // add a new historical record by snapshotting the Anchor's current neighbors
-    bytes32[1] memory history = getLatestNeighborRoots();
-    rootHistory[latestHistoryIndex] = history;
-    // set the next history index modulo pruning length
-    latestHistoryIndex = latestHistoryIndex % pruningLength;
-    emit RootHistoryRecorded(block.timestamp, history);
-  }
-
   function addEdge(
     uint256 sourceChainID,
     bytes32 root,
@@ -59,11 +50,13 @@ abstract contract LinkableAnchorPoseidon2 is AnchorPoseidon2, ILinkableAnchor {
     });
     edgeList.push(edge);
     edgeIndex[sourceChainID] = index;
+    // add to root histories
+    uint32 neighborRootIndex = 0;
+    neighborRoots[sourceChainID][neighborRootIndex] = root;
     emit EdgeAddition(sourceChainID, height, root);
     // emit update event
     bytes32[1] memory neighbors = getLatestNeighborRoots();
     emit RootHistoryUpdate(block.timestamp, neighbors);
-
   }
 
   function updateEdge(
@@ -80,6 +73,10 @@ abstract contract LinkableAnchorPoseidon2 is AnchorPoseidon2, ILinkableAnchor {
       root: root,
       height: height
     });
+     // add to root histories
+    uint32 neighborRootIndex = (currentNeighborRootIndex[sourceChainID] + 1) % ROOT_HISTORY_SIZE;
+    currentNeighborRootIndex[sourceChainID] = neighborRootIndex;
+    neighborRoots[sourceChainID][neighborRootIndex] = root;
     emit EdgeUpdate(sourceChainID, height, root);
     // emit update event
     bytes32[1] memory neighbors = getLatestNeighborRoots();

contracts/interfaces/ILinkableAnchor.sol

@@ -8,7 +8,6 @@ pragma solidity ^0.8.0;
 interface ILinkableAnchor {
   function setHandler(address _handler) external;
   function setBridge(address _bridge) external;
-  function recordHistory() external;
   function hasEdge(uint256 _chainID) external view returns (bool);
   function addEdge(
     uint256 sourceChainID,
@@ -20,4 +19,4 @@ interface ILinkableAnchor {
     bytes32 root,
     uint256 height
   ) external payable;
-}
+}