RFC-1: Bitcoin Like Server with UTXO based transaction

rfc-1/CentralServer/.gitignore

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+# Logs
+logs
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+.pnp.*

rfc-1/CentralServer/index.js

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+const express = require('express');
+const mongoose = require('mongoose');
+const http = require('http');
+const WebSocket = require('ws');
+const nacl = require('tweetnacl');
+const { PublicKey } = require('@solana/web3.js');
+const crypto = require('crypto');
+const axios = require('axios');
+const Mempool = require('./model/mempool');
+const Miner = require('./model/miner');
+const Block = require("./model/block");
+const cors = require('cors');
+
+
+const app = express();
+app.use(cors());
+const httpServer = http.createServer(app);
+const wss = new WebSocket.Server({ server: httpServer });
+
+mongoose.connect('mongodb://localhost:27017/bitcoin_simulator');
+
+app.use(express.json());
+
+let connectedMiners = {};
+
+function generateMinerId() {
+    return crypto.randomBytes(16).toString('hex');
+}
+
+function generateHash(data) {
+    return crypto.createHash('sha256').update(data).digest();
+}
+
+function verifySignature(message, signatureHex, pubKeyBase58) {
+    const hash = generateHash(message);
+    const signature = Buffer.from(signatureHex, 'hex');
+
+    try {
+        const publicKey = new PublicKey(pubKeyBase58);
+        return nacl.sign.detached.verify(hash, signature, publicKey.toBuffer());
+    } catch (err) {
+        console.error('Error verifying signature:', err);
+        return false;
+    }
+}
+
+async function handleNewTransaction(transaction) {
+    const { sender_pub_id, receiver_pub_id, amount, timestamp, signature } = transaction;
+    const message = `${sender_pub_id}${receiver_pub_id}${amount}${timestamp}`;
+
+    try {
+        const isSignatureValid = verifySignature(message, signature, sender_pub_id);
+
+        if (isSignatureValid) {
+            await Mempool.create(transaction);
+            distributeTransactionToMiner(transaction);
+        } else {
+            console.log('Invalid transaction detected.');
+        }
+    } catch (err) {
+        console.error('Error handling new transaction:', err);
+    }
+}
+
+async function distributeTransactionToMiner(transaction) {
+    const minerIds = Object.keys(connectedMiners);
+
+    if (minerIds.length > 0) {
+        const minerIndex = Math.floor(Math.random() * minerIds.length);
+        const minerId = minerIds[minerIndex];
+        wss.clients.forEach((wsClient) => {
+            if (wsClient.readyState === WebSocket.OPEN && wsClient.minerId === minerId) {
+                wsClient.send(JSON.stringify({
+                    type: 'NEW_TRANSACTION',
+                    payload: transaction,
+                }));
+            }
+        });
+
+        console.log(`Transaction ${transaction.signature} sent to miner ${minerId}`);
+    } else {
+        console.log('No miners are currently connected.');
+    }
+}
+
+async function updateMinerStatus(minerId, isConnected) {
+    if (isConnected) {
+        connectedMiners[minerId] = true;
+    } else {
+        delete connectedMiners[minerId];
+    }
+
+    await Miner.findOneAndUpdate(
+        { minerId },
+        { isConnected },
+        { upsert: true, new: true }
+    );
+}
+
+async function handleNewBlock(blockData) {
+    try {
+        const { previousHash, transactions, nonce, timestamp, hash } = blockData;
+        const lastBlock = await Block.findOne().sort({ _id: -1 });
+        if (lastBlock && lastBlock.hash !== previousHash) {
+            console.log('Invalid block: Previous hash does not match');
+            return;
+        }
+
+        // Verify each transaction in the block
+        for (const tx of transactions) {
+            const { sender_pub_id, receiver_pub_id, amount, timestamp, signature } = tx;
+            const message = `${sender_pub_id}${receiver_pub_id}${amount}${timestamp}`;
+            const isSignatureValid = verifySignature(message, signature, sender_pub_id);
+
+            if (!isSignatureValid) {
+                console.log(`Invalid transaction in block: ${signature}`);
+                return;
+            }
+
+            // If valid, call /maketxn to complete the transaction
+            await axios.post('http://localhost:3002/maketxn', {
+                amount,
+                sender_pub_id,
+                receiver_pub_id,
+                signature,
+                timestamp,
+            });
+        }
+
+        await Block.create(blockData);
+
+        // Remove transactions from the mempool after they are added to a block
+        for (const tx of transactions) {
+            await Mempool.deleteOne({ signature: tx.signature });
+        }
+
+        console.log('New block added to the blockchain:', blockData);
+
+        // Broadcast the new block to all connected clients
+        wss.clients.forEach((wsClient) => {
+            if (wsClient.readyState === WebSocket.OPEN) {
+                wsClient.send(JSON.stringify({
+                    type: 'NEW_BLOCK_BROADCAST',
+                    payload: blockData,
+                }));
+            }
+        });
+    } catch (err) {
+        console.error('Error handling new block:', err);
+    }
+}
+
+app.post('/api/submit-transaction', async (req, res) => {
+    const { signature, sender_pub_id, receiver_pub_id, amount, timestamp } = req.body;
+
+    if (!signature || !sender_pub_id || !receiver_pub_id || !amount || !timestamp) {
+        return res.status(400).json({ msg: 'Missing required fields' });
+    }
+
+    const transaction = { signature, sender_pub_id, receiver_pub_id, amount, timestamp };
+    try {
+        await handleNewTransaction(transaction);
+        res.status(200).json({ msg: 'Transaction received and added to mempool' });
+    } catch (err) {
+        res.status(500).json({ msg: 'Internal server error' });
+    }
+});
+
+wss.on('connection', async (ws) => {
+    const minerId = generateMinerId();
+    ws.minerId = minerId;
+    await updateMinerStatus(minerId, true);
+
+    console.log(`Miner ${minerId} connected`);
+
+    // Send the blockchain immediately after connection
+    try {
+        const blockchain = await Block.find().sort({ _id: 1 });
+        ws.send(JSON.stringify({
+            type: 'BLOCKCHAIN',
+            payload: blockchain,
+            version: '1.0.0',
+        }));
+        console.log(`Blockchain sent to miner ${minerId}`);
+    } catch (err) {
+        console.error('Error sending blockchain:', err);
+    }
+
+    ws.on('message', async (message) => {
+        const parsedMessage = JSON.parse(message);
+        const { type, payload } = parsedMessage;
+
+        if (type === 'NEW_BLOCK') {
+            await handleNewBlock(payload);
+        }
+    });
+
+    ws.on('close', async () => {
+        await updateMinerStatus(minerId, false);
+    });
+});
+
+httpServer.listen(3001, () => {
+    console.log('HTTP server running on http://localhost:3001');
+    console.log('WebSocket server running on ws://localhost:3001');
+});

rfc-1/CentralServer/model/block.js

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+const mongoose = require('mongoose');
+
+const blockSchema = new mongoose.Schema({
+    index: Number,
+    timestamp: Date,
+    transactions: Array,
+    previousHash: String,
+    hash: String,
+    nonce: Number
+});
+
+module.exports = mongoose.model('Block', blockSchema);

rfc-1/CentralServer/model/mempool.js

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+const mongoose = require('mongoose');
+
+const mempoolSchema = new mongoose.Schema({
+    signature: { type: String, required: true, unique: true },
+    sender_pub_id: { type: String, required: true },
+    receiver_pub_id: { type: String, required: true },
+    amount: { type: Number, required: true },
+    timestamp: { type: Date, default: Date.now, required: true },
+});
+
+const Mempool = mongoose.model('Mempool', mempoolSchema);
+
+module.exports = Mempool;

rfc-1/CentralServer/model/miner.js

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+const mongoose = require('mongoose');
+
+const minerSchema = new mongoose.Schema({
+    minerId: String,
+    connected: Boolean,
+    lastSeen: Date
+});
+
+module.exports = mongoose.model('Miner', minerSchema);