Bitswap Protocol Implementation in py-libp2p

[sumanjeet0012]

Bitswap Protocol Implementation Progress Report

PR Link: #980

🚀 Current Status

Hey @seetadev, I've successfully completed the implementation of Bitswap protocol for py-libp2p as part of enhancing the file sharing and content exchange capabilities. Here's the comprehensive overview of what has been accomplished:

✅ Implementation Complete - All Features Working:

The Bitswap protocol implementation is fully functional and ready for production use. All core components have been implemented and tested:

1. Complete Bitswap Protocol Implementation

   • Full client-side implementation for block request/response
   • Block storage with abstract interface and in-memory implementation
   • Protocol-compliant message handling and validation (v1.0.0, v1.1.0, v1.2.0)
   • Proper error handling with comprehensive exception hierarchy

2. BitswapClient

   • Block request and retrieval from peers
   • Wantlist management with priority support
   • Block exchange with automatic protocol version negotiation
   • Connection management and stream handling

3. Merkle DAG Manager (MerkleDag)

   • File chunking and DAG construction
   • Multi-block file storage and retrieval
   • Automatic CID computation and verification
   • Progress tracking with callback support

4. Block Storage

   • Abstract BlockStore interface for pluggable storage
   • In-memory implementation (MemoryBlockStore)
   • Async/await API throughout
   • Type-safe CID handling

🔧 Implementation Structure:

Following modular design principles with complete separation of concerns:

libp2p/bitswap/
├── __init__.py           # ✅ Complete - module exports and public API
├── client.py             # ✅ Complete - BitswapClient implementation (v1.0.0, v1.1.0, v1.2.0)
├── block_store.py        # ✅ Complete - Abstract storage interface + in-memory implementation
├── messages.py           # ✅ Complete - Protocol message creation and parsing
├── config.py             # ✅ Complete - Protocol configuration and constants
├── cid.py                # ✅ Complete - CID computation and verification utilities
├── errors.py             # ✅ Complete - Comprehensive error handling
├── dag.py                # ✅ Complete - MerkleDag for file operations
├── dag_pb.py             # ✅ Complete - DAG-PB encoding/decoding
├── chunker.py            # ✅ Complete - File chunking utilities
└── pb/                   # ✅ Complete - Protocol buffer definitions
    ├── __init__.py       # ✅ Complete
    ├── bitswap_pb2.py    # ✅ Complete - Bitswap protobuf messages
    ├── dag_pb_pb2.py     # ✅ Complete - DAG-PB protobuf messages
    └── unixfs_pb2.py     # ✅ Complete - UnixFS protobuf messages

examples/bitswap/
└── bitswap.py            # ✅ Complete - comprehensive demo with provider/client modes

tests/core/bitswap/
├── test_client.py        # ✅ Complete - unit tests
├── test_block_store.py   # ✅ Complete - storage tests
├── test_messages.py      # ✅ Complete - message tests
├── test_cid.py           # ✅ Complete - CID tests
├── test_dag.py           # ✅ Complete - DAG tests
├── test_integration.py   # ✅ Complete - integration tests
└── (additional test files)

🛠️ How it Works (Current Flow):

Provider Flow:

• Provider adds file to Merkle DAG with automatic chunking
• Each chunk is stored with content-addressed CID
• Provider listens for wantlist requests from peers
• When requested, provider sends blocks via Bitswap protocol

Client Flow:

• Client connects to provider using multiaddr
• Client requests file using root CID
• MerkleDag automatically resolves all chunk CIDs
• Bitswap client fetches each chunk from provider
• File is reassembled and verified

Protocol Operation:

• BitswapClient handles incoming protocol streams
• Manages block requests with wantlist and priority
• Implements block exchange with automatic version negotiation
• Proper cleanup and resource management

🎯 Key Features Implemented:

1. Protocol Compliance

   • Full implementation of Bitswap protocol specification (v1.0.0, v1.1.0, v1.2.0)
   • Compatible with go-ipfs and js-ipfs implementations
   • Proper protobuf message handling and validation

2. File Management Features

   • Automatic file chunking (63 KB chunks)
   • Merkle DAG construction and traversal
   • CID computation and verification
   • Directory wrapper support for filename preservation

3. Production-Ready Features

   • Comprehensive error handling and validation
   • Configurable timeouts
   • Stream management with proper cleanup
   • Logging integration for debugging and monitoring

4. Developer Experience

   • Clean, intuitive API design
   • Comprehensive example application
   • Detailed documentation and type hints
   • Integration with py-libp2p's existing patterns

🧪 Testing Status:

✅ Testing Implementation Complete:

The implementation includes comprehensive unit and integration tests:

Required Test Coverage:

• ✅ Unit tests for all core classes (BitswapClient, MerkleDag, BlockStore)
• ✅ Protocol message validation and error handling tests
• ✅ CID computation and verification tests
• ✅ Integration tests with real network scenarios
• ✅ Multi-peer file transfer scenario tests

Current Validation:

• ✅ All tests passing in CI/CD pipeline
• ✅ Manual testing performed through the example application
• ✅ Core functionality verified in both provider and client modes
• ✅ Protocol message handling validated through practical usage
• ✅ Integration with py-libp2p host verified

🌟 Advanced Configuration Options:

The implementation provides extensive configuration capabilities:

# Protocol Configuration
BITSWAP_PROTOCOL_V100 = TProtocol("/ipfs/bitswap/1.0.0")
BITSWAP_PROTOCOL_V110 = TProtocol("/ipfs/bitswap/1.1.0")
BITSWAP_PROTOCOL_V120 = TProtocol("/ipfs/bitswap/1.2.0")

# Size Limits
MAX_MESSAGE_SIZE = 4 * 1024 * 1024  # 4MiB
MAX_BLOCK_SIZE = 63 * 1024          # 63 KB
DEFAULT_CHUNK_SIZE = 63 * 1024      # 63 KB

# Operation Defaults
DEFAULT_PRIORITY = 1
DEFAULT_TIMEOUT = 30  # seconds
MAX_CONCURRENT_REQUESTS = 100
DEFAULT_WANTLIST_SIZE = 256

🔥 Example Usage:

The implementation includes a comprehensive example that demonstrates both provider and client modes:

# Start a provider (share a file)
python examples/bitswap/bitswap.py --mode provider --file <file_path>

# Run a client (download by CID)
python examples/bitswap/bitswap.py --mode client \
  --provider <multiaddr> \
  --cid <root_cid> \
  --output <output_path>

📋 What's Ready for Production:

✅ Fully Complete Components:

• Complete Bitswap protocol implementation (v1.0.0, v1.1.0, v1.2.0)
• Merkle DAG manager for file operations
• Block storage with abstract interface
• CID utilities and verification
• Protocol buffer definitions and message handling
• Comprehensive error handling and validation
• Production-ready configuration management
• Detailed example application for reference
• Unit and integration tests with CI/CD integration
• Background task management with proper lifecycle

🎯 Next Steps:

The implementation is feature-complete and ready for use. Future enhancements may include:

1. Additional Storage Backends - Implement persistent storage options (SQLite, filesystem-based)
2. Performance Optimizations - Add block caching, parallel fetching strategies
3. Enhanced Monitoring - Integrate Prometheus metrics, performance benchmarking

The Bitswap protocol implementation provides a robust, scalable, and production-ready solution for decentralized file sharing in py-libp2p applications, offering full IPFS compatibility and protocol compliance.

[sumanjeet0012]

Bitswap.screencast.mov

[seetadev]

Wonderful documentation, @sumanjeet0012 . Appreciate your great efforts.