Building a Cross-Chain Aggregator: Architecture Deep Dive

#solidity #web3 #defi #python

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.20;

// Core Aggregator Contract
contract CrossChainAggregator {
    mapping(bytes32 => bool) public processedHashes;
    mapping(uint256 => address) public validators;
    uint256 public validatorCount;

    event CrossChainSwap(
        bytes32 indexed swapId,
        address indexed user,
        uint256 sourceChain,
        uint256 destChain,
        uint256 amount
    );

    modifier onlyValidator() {
        require(validators[block.chainid] == msg.sender, "Not validator");
        _;
    }

    function initiateSwap(
        address token,
        uint256 amount,
        uint256 destChainId
    ) external returns (bytes32 swapId) {
        swapId = keccak256(abi.encodePacked(msg.sender, token, amount, block.timestamp));
        require(!processedHashes[swapId], "Already processed");

        // Lock tokens
        IERC20(token).transferFrom(msg.sender, address(this), amount);

        emit CrossChainSwap(swapId, msg.sender, block.chainid, destChainId, amount);
        return swapId;
    }

    function finalizeSwap(
        bytes32 swapId,
        address user,
        uint256 amount,
        bytes calldata signature
    ) external onlyValidator {
        require(!processedHashes[swapId], "Already finalized");
        require(verifySignature(swapId, user, amount, signature), "Invalid signature");

        processedHashes[swapId] = true;
        // Release tokens on destination chain
        IERC20(token).transfer(user, amount);
    }
}

# microservice_router.py - Core routing logic
import asyncio
from web3 import Web3
from typing import Dict, List
import aiohttp
import redis

class CrossChainRouter:
    def __init__(self, config: Dict):
        self.redis_client = redis.Redis(host='localhost', port=6379, db=0)
        self.validators = config['validators']
        self.chain_connections: Dict[int, Web3] = {}
        self.pending_swaps = asyncio.Queue()

    async def route_swap(self, swap_data: Dict) -> bytes32:
        # 25 microservice modules
        modules = {
            'auth': AuthService(),
            'liquidity': LiquidityAggregator(),
            'price': PriceOracle(),
            'bridge': BridgeConnector(),
            'validator': ValidatorPool(),
            'monitor': MonitoringService(),
            'security': SecurityAuditor(),
            'gas': GasOptimizer(),
            'slippage': SlippageCalculator(),
            'path': PathFinder(),
            'arbitrage': ArbitrageDetector(),
            'risk': RiskManager(),
            'compliance': ComplianceChecker(),
            'analytics': AnalyticsEngine(),
            'cache': CacheLayer(),
            'queue': MessageQueue(),
            'db': DatabaseService(),
            'api': APIHandler(),
            'websocket': WebSocketManager(),
            'rate_limit': RateLimiter(),
            'backup': BackupService(),
            'recovery': DisasterRecovery(),
            'logging': LogAggregator(),
            'alert': AlertSystem(),
            'metrics': MetricsCollector()
        }

        # Execute through pipeline
        for module_name, module in modules.items():
            swap_data = await module.process(swap_data)

        return swap_data['swap_id']

    async def monitor_health(self):
        # Monitoring with Prometheus metrics
        while True:
            metrics = {
                'active_swaps': self.pending_swaps.qsize(),
                'validator_count': len(self.validators),
                'latency_ms': await self._measure_latency(),
                'error_rate': await self._get_error_rate()
            }

            # Push to monitoring service
            await self._push_metrics(metrics)
            await asyncio.sleep(5)

    async def security_check(self, swap_data: Dict) -> bool:
        # Multi-layer security
        checks = [
            self._verify_signature(swap_data),
            self._check_replay_attack(swap_data),
            self._validate_amount_limits(swap_data),
            self._detect_sandwich_attack(swap_data),
            self._check_blacklist(swap_data['user']),
            self._verify_chain_consistency(swap_data)
        ]

        results = await asyncio.gather(*checks)
        return all(results)

    def _verify_signature(self, data: Dict) -> bool:
        # ECDSA signature verification
        message_hash = Web3.solidity_keccak(
            ['address', 'uint256', 'uint256', 'bytes32'],
            [data['user'], data['amount'], data['dest_chain'], data['swap_id']]
        )
        return Web3().eth.account.recover_message(
            message_hash, signature=data['signature']
        ) in self.validators

# P2P Cluster Node
class P2PNode:
    def __init__(self, node_id: str, peers: List[str]):
        self.node_id = node_id
        self.peers = peers
        self.blockchain = []
        self.state = {}

    async def broadcast_swap(self, swap: Dict):
        # Gossip protocol for P2P
        for peer in self.peers:
            async with aiohttp.ClientSession() as session:
                await session.post(f'http://{peer}/swap', json=swap)

    async def validate_and_consensus(self, swap: Dict):
        # PBFT-like consensus
        votes = 0
        threshold = len(self.peers) * 2 // 3 + 1

        for peer in self.peers:
            response = await self._request_validation(peer, swap)
            if response['valid']:
                votes += 1

        return votes >= threshold

# monitoring_stack.py
from prometheus_client import start_http_server, Counter, Histogram, Gauge
import time
import asyncio

# Metrics
SWAP_COUNTER = Counter('cross_chain_swaps_total', 'Total swaps processed')
SWAP_LATENCY = Histogram('swap_latency_seconds', 'Swap processing time')
ACTIVE_VALIDATORS = Gauge('active_validators', 'Number of active validators')
ERROR_COUNTER = Counter('swap_errors_total', 'Total swap errors')

class MonitoringStack:
    def __init__(self):
        start_http_server(8000)

    async def track_swap(self, swap_func):
        SWAP_COUNTER.inc()
        start_time = time.time()

        try:
            result = await swap_func()
            SWAP_LATENCY.observe(time.time() - start_time)
            return result
        except Exception as e:
            ERROR_COUNTER.inc()
            raise e

    async def update_validator_metrics(self, validators: list):
        ACTIVE_VALIDATORS.set(len(validators))

    async def alert_on_anomaly(self, metrics: dict):
        if metrics['error_rate'] > 0.05:  # 5% error threshold
            await self._send_alert('High error rate detected')
        if metrics['latency_ms'] > 5000:  # 5 second threshold
            await self._send_alert('High latency detected')

# Security Module
class SecurityModule:
    def __init__(self):
        self.rate_limiter = RateLimiter(max_requests=100, window=60)
        self.replay_protector = ReplayProtector()
        self.signer = ECDSASigner()

    async def validate_transaction(self, tx: dict) -> bool:
        # Rate limiting
        if not await self.rate_limiter.check(tx['user']):
            return False

        # Replay protection
        if await self.replay_protector.is_duplicate(tx['hash']):
            return False

        # Signature verification
        if not self.signer.verify(tx):
            return False

        # Amount validation
        if tx['amount'] > 1000000:  # Max 1M tokens
            return False

        return True

    async def encrypt_communication(self, data: bytes) -> bytes:
        # TLS 1.3 encryption
        return await self._tls_encrypt(data)