serai/coins/ethereum/contracts/Router.sol

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// SPDX-License-Identifier: AGPLv3
pragma solidity ^0.8.0;
import "./Schnorr.sol";
contract Router is Schnorr {
// Contract initializer
// TODO: Replace with a MuSig of the genesis validators
address public initializer;
// Nonce is incremented for each batch of transactions executed
uint256 public nonce;
// fixed parity for the public keys used in this contract
uint8 constant public KEY_PARITY = 27;
// current public key's x-coordinate
// note: this key must always use the fixed parity defined above
bytes32 public seraiKey;
struct OutInstruction {
address to;
uint256 value;
bytes data;
}
struct Signature {
bytes32 c;
bytes32 s;
}
// success is a uint256 representing a bitfield of transaction successes
event Executed(uint256 nonce, bytes32 batch, uint256 success);
// error types
error NotInitializer();
error AlreadyInitialized();
error InvalidKey();
error TooManyTransactions();
constructor() {
initializer = msg.sender;
}
// initSeraiKey can be called by the contract initializer to set the first
// public key, only if the public key has yet to be set.
function initSeraiKey(bytes32 _seraiKey) external {
if (msg.sender != initializer) revert NotInitializer();
if (seraiKey != 0) revert AlreadyInitialized();
if (_seraiKey == bytes32(0)) revert InvalidKey();
seraiKey = _seraiKey;
}
// updateSeraiKey validates the given Schnorr signature against the current public key,
// and if successful, updates the contract's public key to the given one.
function updateSeraiKey(
bytes32 _seraiKey,
Signature memory sig
) public {
if (_seraiKey == bytes32(0)) revert InvalidKey();
bytes32 message = keccak256(abi.encodePacked("updateSeraiKey", _seraiKey));
if (!verify(KEY_PARITY, seraiKey, message, sig.c, sig.s)) revert InvalidSignature();
seraiKey = _seraiKey;
}
// execute accepts a list of transactions to execute as well as a Schnorr signature.
// if signature verification passes, the given transactions are executed.
// if signature verification fails, this function will revert.
function execute(
OutInstruction[] calldata transactions,
Signature memory sig
) public {
if (transactions.length > 256) revert TooManyTransactions();
bytes32 message = keccak256(abi.encode("execute", nonce, transactions));
// This prevents re-entrancy from causing double spends yet does allow
// out-of-order execution via re-entrancy
nonce++;
if (!verify(KEY_PARITY, seraiKey, message, sig.c, sig.s)) revert InvalidSignature();
uint256 successes;
for(uint256 i = 0; i < transactions.length; i++) {
(bool success, ) = transactions[i].to.call{value: transactions[i].value, gas: 200_000}(transactions[i].data);
assembly {
successes := or(successes, shl(i, success))
}
}
emit Executed(nonce, message, successes);
}
}