Future Improvements

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Overview

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Piece Selection Strategies

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Rarest-First Strategy

• Better piece distribution across the network
• Reduces risk of a piece becoming unavailable if seeders leave
• Improves overall swarm health
• Faster distribution in scenarios with limited seeders

// Proposed implementation in _scheduleRequests()
function selectRarestPiece(availablePieces, peerAvailability) {
  let rarest = null;
  let minCount = Infinity;
  
  for (let piece of this.missingPieces) {
    let count = 0;
    for (let peer of this.knownPeers.values()) {
      if (peer.availablePieces.has(piece)) count++;
    }
    if (count < minCount && count > 0) {
      minCount = count;
      rarest = piece;
    }
  }
  
  return rarest;
}

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Random First for Initial Pieces

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Bandwidth Management

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Choking and Unchoking

• Limit simultaneous uploads to N peers (e.g., 4 peers)
• Rotate unchoked peers every 10-30 seconds
• Implement “optimistic unchoking” to discover faster peers
• Prefer peers with better upload/download ratios

• Prevents bandwidth saturation
• Encourages reciprocal sharing (tit-for-tat)
• Improves performance for all peers
• Reduces network congestion

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Connection Resilience

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Timeout Mechanisms

• Set timeout for piece requests (e.g., 30 seconds)
• Re-request timed-out pieces from other peers
• Track peer response times and prioritize faster peers

// Proposed timeout tracking
class Node {
  constructor() {
    this.pieceTimeouts = new Map(); // pieceIndex -> timestamp
  }
  
  _sendRequest(socket, index) {
    this.pieceTimeouts.set(index, Date.now());
    // ... existing code
  }
  
  _checkTimeouts() {
    const now = Date.now();
    for (let [index, timestamp] of this.pieceTimeouts) {
      if (now - timestamp > 30000) { // 30 second timeout
        this.pendingPieces.delete(index);
        this.pieceTimeouts.delete(index);
        this._scheduleRequests(); // Re-request
      }
    }
  }
}

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Automatic Reconnection

• Automatically attempt to reconnect to known peers if connection drops
• Implement exponential backoff for reconnection attempts
• Maintain a list of previously successful peer addresses
• Persist peer list to disk for recovery after crashes

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Security Enhancements

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Encryption and TLS Support

const tls = require('tls');

// Replace net.createServer with tls.createServer
this.server = tls.createServer({
  key: fs.readFileSync('private-key.pem'),
  cert: fs.readFileSync('certificate.pem')
}, socket => {
  // ... existing socket handling
});

// Replace net.connect with tls.connect
const socket = tls.connect(port, host, {
  rejectUnauthorized: false // or implement cert verification
}, () => {
  // ... existing connection handling
});

• Protects file data from eavesdropping
• Prevents man-in-the-middle attacks
• Ensures data integrity during transmission

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Peer Authentication

• Implement peer identity verification
• Use public key cryptography for authentication
• Prevent unauthorized peers from joining swarms
• Optional: require shared secret for private swarms

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Data Integrity

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Per-Piece Hash Verification

• Early detection of corrupted pieces
• Re-request corrupted pieces immediately
• No need to re-download entire file if corruption detected
• Better resilience to network errors

// During file preparation (seeder)
class Manager {
  async computePieceHashes() {
    this.pieceHashes = [];
    for (let i = 0; i < this.numPieces; i++) {
      const buffer = await this.readPiece(i);
      const hash = crypto.createHash('sha1')
        .update(buffer)
        .digest('hex');
      this.pieceHashes.push(hash);
    }
    return this.pieceHashes;
  }
}

// During piece receipt (leecher)
async _handlePiece(socket, message) {
  const index = message.index;
  const dataBuffer = Buffer.from(message.data, 'base64');
  
  // Verify piece hash before writing
  const receivedHash = crypto.createHash('sha1')
    .update(dataBuffer)
    .digest('hex');
  
  if (receivedHash !== this.pieceHashes[index]) {
    console.warn(`Piece ${index} hash mismatch! Re-requesting...`);
    this.pendingPieces.delete(index);
    return; // Don't write corrupted piece
  }
  
  await this.fileManager.writePiece(index, dataBuffer);
  // ... existing code
}

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Merkle Tree Verification

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Performance Optimizations

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Large File Handling

1. Dynamic Piece Size:
   • Adjust piece size based on file size
   • Larger files → larger pieces (e.g., 256 KiB or 1 MiB)
   • Reduces overhead from excessive piece count
2. Piece Pipelining:
   • Request multiple pieces from same peer simultaneously
   • Reduce round-trip latency impact
   • Currently only one piece per peer at a time
3. Streaming Support:
   • Enable playback/use of file while still downloading
   • Prioritize pieces in sequential order when requested
   • Useful for video streaming scenarios

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Memory Optimization

• Stream piece data instead of loading entire pieces into memory
• Implement piece caching with LRU eviction
• Use memory-mapped files for large file operations

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Protocol Enhancements

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Extended Messaging

• handshake, bitfield, request, piece, have, peers

1. cancel - Cancel a pending piece request
   { type: 'cancel', index: 42 }
   
2. port - Advertise DHT port (future DHT support)
   { type: 'port', port: 6881 }
   
3. keepalive - Maintain connection during idle periods
   { type: 'keepalive' }
   
4. metadata - Exchange additional file metadata
   { 
     type: 'metadata', 
     fileName: 'video.mkv',
     contentType: 'video/x-matroska',
     creationDate: '2026-03-06'
   }
   

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Compression

const zlib = require('zlib');

// Before sending
const compressed = zlib.gzipSync(dataBuffer);
const pieceMsg = {
  type: 'piece',
  index: index,
  data: compressed.toString('base64'),
  compressed: true
};

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Advanced Features

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Distributed Hash Table (DHT)

• No need for initial peer addresses
• Peers can find each other automatically
• Improved network resilience
• Truly distributed architecture

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Tracker Support

• Easier coordination in managed networks
• Faster initial peer discovery
• Statistics and monitoring capabilities

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Magnet Links

magnet:?xt=urn:sha1:a1b2c3d4e5f6&dn=movie.mkv&xl=157286400

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Web Interface

• Real-time download progress
• Connected peers visualization
• Bandwidth usage graphs
• File management

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Monitoring and Diagnostics

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Enhanced Logging

• Structured logging with log levels (DEBUG, INFO, WARN, ERROR)
• Log rotation and archival
• Export logs in JSON format for analysis
• Performance metrics logging

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Statistics Dashboard

• Total bytes uploaded/downloaded
• Per-peer transfer rates
• Piece availability distribution
• Network topology visualization
• Average piece download time
• Connection uptime statistics

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Multi-File Support

• Create manifest file listing all files and their offsets
• Map pieces across multiple files
• Allow selective file downloading

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Contributing