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feat: add leaf validation, code comments
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@QEDK
QEDK committed Dec 18, 2023
1 parent 94b424f commit 8440f68
Showing 1 changed file with 58 additions and 46 deletions.
104 changes: 58 additions & 46 deletions src/AvailBridge.sol
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Original file line number Diff line number Diff line change
Expand Up @@ -18,10 +18,13 @@ import {IMessageReceiver} from "src/interfaces/IMessageReceiver.sol";
/**
* @author @QEDK (Avail)
* @title AvailBridge
* @notice An arbitrary message bridge between Avail <-> Ethereum
* @notice An arbitrary message bridge between Avail <-> Ethereum
* @custom:security security@availproject.org
*/
contract AvailBridge is Initializable, Ownable2StepUpgradeable, ReentrancyGuardUpgradeable {
using Merkle for bytes32[];
using SafeERC20 for IERC20;

struct Message {
bytes1 messageType;
bytes32 from;
Expand All @@ -35,7 +38,6 @@ contract AvailBridge is Initializable, Ownable2StepUpgradeable, ReentrancyGuardU
struct MerkleProofInput {
bytes32[] dataRootProof;
bytes32[] leafProof;
bytes32 dataRoot;
bytes32 rangeHash;
uint256 dataRootIndex;
bytes32 blobRoot;
Expand All @@ -44,14 +46,12 @@ contract AvailBridge is Initializable, Ownable2StepUpgradeable, ReentrancyGuardU
uint256 leafIndex;
}

using Merkle for bytes32[];
using SafeERC20 for IERC20;

bytes1 private constant TOKEN_TX_PREFIX = 0x02;
uint32 private constant AVAIL_DOMAIN = 1;
uint32 private constant ETH_DOMAIN = 2;
// Derived from abi.encodePacked("ETH")
// slither-disable-next-line too-many-digits
bytes32 private constant ETH_ASSET_ID = 0x4554480000000000000000000000000000000000000000000000000000000000;
bytes1 private constant TOKEN_TRANSFER_MESSAGE_TYPE = 0x02;
IVectorx public vectorx;
IWrappedAvail public avail;
uint256 public messageId;
Expand All @@ -60,24 +60,24 @@ contract AvailBridge is Initializable, Ownable2StepUpgradeable, ReentrancyGuardU
mapping(uint256 => bytes32) public isSent;
mapping(bytes32 => address) public tokens;

event MessageReceived(bytes32 indexed from, address indexed to, uint256 messageId);
event MessageSent(address indexed from, bytes32 indexed to, uint256 messageId);

error ArrayLengthMismatch();
error InvalidDataRootProof();
error DataRootCommitmentEmpty();
error BlobRootEmpty();
error BridgeRootEmpty();
error InvalidLeaf();
error InvalidAssetId();
error InvalidMerkleProof();
error InvalidDataRoot();
error InvalidDomain();
error InvalidDestinationOrAmount();
error InvalidMessage();
error InvalidFungibleTokenTransfer();
error UnlockFailed();
error AlreadyBridged();

event MessageReceived(bytes32 indexed from, address indexed to, uint256 messageId);
event MessageSent(address indexed from, bytes32 indexed to, uint256 messageId);

modifier onlySupportedDomain(uint32 originDomain, uint32 destinationDomain) {
if (originDomain != AVAIL_DOMAIN || destinationDomain != ETH_DOMAIN) {
revert InvalidDomain();
Expand Down Expand Up @@ -131,35 +131,6 @@ contract AvailBridge is Initializable, Ownable2StepUpgradeable, ReentrancyGuardU
}
}

/**
* @notice Takes a Merkle tree proof of inclusion for a bridge leaf and verifies it
* @param input Merkle tree proof of inclusion for the bridge leaf
* @return bool Returns true if the bridge leaf is valid, else false
*/
function verifyBridgeLeaf(MerkleProofInput calldata input) public view returns (bool) {
if (input.bridgeRoot == 0x0) {
revert BridgeRootEmpty();
}
_checkDataRoot(input);
// leaf must be keccak(message)
return input.leafProof.verify(input.bridgeRoot, input.leafIndex, input.leaf);
}

/**
* @notice Takes a Merkle tree proof of inclusion for a blob leaf and verifies it
* @dev This function is used for data attestation on Ethereum
* @param input Merkle tree proof of inclusion for the blob leaf
* @return bool Returns true if the blob leaf is valid, else false
*/
function verifyBlobLeaf(MerkleProofInput calldata input) external view returns (bool) {
if (input.blobRoot == 0x0) {
revert BlobRootEmpty();
}
_checkDataRoot(input);
// leaf must be keccak(blob)
return input.leafProof.verify(input.blobRoot, input.leafIndex, keccak256(abi.encode(input.leaf)));
}

/**
* @notice Takes an arbitrary message and its proof of inclusion, verifies and executes it (if valid)
* @dev This function is used for passing arbitrary data from Avail to Ethereum
Expand Down Expand Up @@ -274,7 +245,7 @@ contract AvailBridge is Initializable, Ownable2StepUpgradeable, ReentrancyGuardU
function sendAVL(bytes32 recipient, uint256 amount) external checkDestAmt(recipient, amount) {
uint256 id = messageId++;
Message memory message = Message(
TOKEN_TRANSFER_MESSAGE_TYPE,
TOKEN_TX_PREFIX,
bytes32(bytes20(msg.sender)),
recipient,
ETH_DOMAIN,
Expand All @@ -297,7 +268,7 @@ contract AvailBridge is Initializable, Ownable2StepUpgradeable, ReentrancyGuardU
function sendETH(bytes32 recipient) external payable checkDestAmt(recipient, msg.value) {
uint256 id = messageId++;
Message memory message = Message(
TOKEN_TRANSFER_MESSAGE_TYPE,
TOKEN_TX_PREFIX,
bytes32(bytes20(msg.sender)),
recipient,
ETH_DOMAIN,
Expand All @@ -324,7 +295,7 @@ contract AvailBridge is Initializable, Ownable2StepUpgradeable, ReentrancyGuardU
}
uint256 id = messageId++;
Message memory message = Message(
TOKEN_TRANSFER_MESSAGE_TYPE,
TOKEN_TX_PREFIX,
bytes32(bytes20(msg.sender)),
recipient,
ETH_DOMAIN,
Expand All @@ -339,6 +310,38 @@ contract AvailBridge is Initializable, Ownable2StepUpgradeable, ReentrancyGuardU
IERC20(token).safeTransferFrom(msg.sender, address(this), amount);
}

/**
* @notice Takes a Merkle tree proof of inclusion for a blob leaf and verifies it
* @dev This function is used for data attestation on Ethereum
* @param input Merkle tree proof of inclusion for the blob leaf
* @return bool Returns true if the blob leaf is valid, else false
*/
function verifyBlobLeaf(MerkleProofInput calldata input) external view returns (bool) {
if (input.blobRoot == 0x0) {
revert BlobRootEmpty();
}
_checkDataRoot(input);
// leaf must be keccak(blob)
// we don't need to check that the leaf is non-zero because hash the pre-image ourselves
return input.leafProof.verify(input.blobRoot, input.leafIndex, keccak256(abi.encodePacked(input.leaf)));
}

/**
* @notice Takes a Merkle tree proof of inclusion for a bridge leaf and verifies it
* @dev This function does not validate that the leaf itself is valid, only that it's included
* @param input Merkle tree proof of inclusion for the bridge leaf
* @return bool Returns true if the bridge leaf is valid, else false
*/
function verifyBridgeLeaf(MerkleProofInput calldata input) public view returns (bool) {
if (input.bridgeRoot == 0x0) {
revert BridgeRootEmpty();
}
_checkDataRoot(input);
// leaf must be keccak(message)
// we don't need to check that the leaf is non-zero because we check that the root is non-zero
return input.leafProof.verify(input.bridgeRoot, input.leafIndex, input.leaf);
}

/**
* @notice Takes a message and its proof of inclusion, verifies and marks it as spent (if valid)
* @dev This function is used for verifying a message and marking it as spent (if valid)
Expand All @@ -350,9 +353,15 @@ contract AvailBridge is Initializable, Ownable2StepUpgradeable, ReentrancyGuardU
if (isBridged[leaf]) {
revert AlreadyBridged();
}
// validate that the leaf being proved is indeed the message hash!
if (input.leaf != leaf) {
revert InvalidLeaf();
}
// check proof of inclusion
if (!verifyBridgeLeaf(input)) {
revert InvalidMerkleProof();
}
// mark as spent
isBridged[leaf] = true;
}

Expand All @@ -366,11 +375,14 @@ contract AvailBridge is Initializable, Ownable2StepUpgradeable, ReentrancyGuardU
if (dataRootCommitment == 0x0) {
revert DataRootCommitmentEmpty();
}
if (!input.dataRootProof.verify(dataRootCommitment, input.dataRootIndex, input.dataRoot)) {
// we construct the data root here internally, it is not possible to create an invalid data root that is
// also part of the commitment tree
if (
!input.dataRootProof.verify(
dataRootCommitment, input.dataRootIndex, keccak256(abi.encode(input.blobRoot, input.bridgeRoot))
)
) {
revert InvalidDataRootProof();
}
if (input.dataRoot != keccak256(abi.encode(input.blobRoot, input.bridgeRoot))) {
revert InvalidDataRoot();
}
}
}

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