tokenbridge-contracts/contracts/helpers/AMBBridgeHelper.sol

66 lines
2.1 KiB
Solidity

pragma solidity 0.4.24;
interface IHomeBridge {
function numMessagesSigned(bytes32 _message) external view returns (uint256);
function isAlreadyProcessed(uint256 _number) external pure returns (bool);
function signature(bytes32 _hash, uint256 _index) external view returns (bytes memory);
}
contract Helper {
function unpackSignature(bytes memory _signature) internal pure returns (bytes32 r, bytes32 s, uint8 v) {
require(_signature.length == 65);
assembly {
r := mload(add(_signature, 0x20))
s := mload(add(_signature, 0x40))
v := mload(add(_signature, 0x41))
}
return (r, s, v);
}
}
contract AMBBridgeHelper is Helper {
address public owner;
IHomeBridge public ambBridge;
constructor(address _homeBridge) public {
owner = msg.sender;
ambBridge = IHomeBridge(_homeBridge);
}
function getSignatures(bytes _message) external view returns (bytes memory) {
bytes32 msgHash = keccak256(abi.encodePacked(_message));
uint256 signed = ambBridge.numMessagesSigned(msgHash);
require(ambBridge.isAlreadyProcessed(signed), "message hasn't been confirmed");
// recover number of confirmations sent by oracles
signed = signed & 0x8fffffffffffffffffffffffffffffffffffffffffff;
require(signed < 0x100);
bytes memory signatures = new bytes(1 + signed * 65);
assembly {
mstore8(add(signatures, 32), signed)
}
for (uint256 i = 0; i < signed; i++) {
bytes memory sig = ambBridge.signature(msgHash, i);
(bytes32 r, bytes32 s, uint8 v) = unpackSignature(sig);
assembly {
mstore8(add(add(signatures, 33), i), v)
mstore(add(add(add(signatures, 33), signed), mul(i, 32)), r)
mstore(add(add(add(signatures, 33), mul(signed, 33)), mul(i, 32)), s)
}
}
return signatures;
}
function clean() external {
require(msg.sender == owner, "not an owner");
selfdestruct(owner);
}
}