srmudp

SRMUDP - Secure Reliable Multi-UDP Chat

This project provides a secure, reliable UDP socket implementation with multi-peer hole punching capabilities for peer-to-peer communication.

Features

• Secure communication using AES-GCM encryption
• Reliable packet delivery with acknowledgment and retransmission
• UDP hole punching for NAT traversal
• Multi-peer connections from a single socket
• Message hooks for processing incoming messages
• Simple chat application built on top of the library

Requirements

• Python 3.6+
• Required Python packages:
  • pycryptodome
  • pyzmq

Installation

pip install -r requirements.txt

Basic Usage

MultiHolepunchSocket

The MultiHolepunchSocket class provides a way to establish multiple peer-to-peer connections using UDP hole punching:

from srmudp_chat import MultiHolepunchSocket

# Create a socket on a specific port
socket = MultiHolepunchSocket(port=8000)

# Add peers
socket.add_peers({
    "peer1": "192.168.1.100:8001",
    "peer2": "example.com:8002"
})

# Send a message to all connected peers
socket.send(b"Hello, everyone!")

# Send a message to a specific peer
socket.send(b"Hello, peer1", recipient="peer1")

# Send a message to multiple peers
socket.send(b"Hello, selected peers", recipient=["peer1", "peer2"])

# Receive a message
msg = socket.receive(timeout=1.0)
if msg:
    print(f"Received: {msg.content} from {msg.peer}")

# Remove a peer
socket.remove_peer("peer1")

# Close the socket
socket.close()

Chat Application

The project includes a simple chat application that demonstrates the use of the MultiHolepunchSocket:

Starting the Chat App

python chat_app.py -p 8000 -n YourNickname

Options:

• -p, --port PORT: Local port to bind to (0 for random)
• -n, --nick NICK: Your nickname in the chat
• -c, --config FILE: Path to a config file with peers
• -v, --verbose: Enable verbose logging

Chat Commands

• /help: Show help message
• /list: List all connected peers
• /add <nick> <addr>: Add a new peer
• /remove <nick>: Remove a peer
• /msg <nick> <message>: Send a private message to a peer
• /save <file>: Save current peers to a config file
• /load <file>: Load peers from a config file
• /quit: Exit the application

Example: Setting Up a Chat Network

Step 1: Start the first chat instance

python chat_app.py -p 8000 -n Alice

Note the IP address and port (check the log messages or use /list).

Step 2: Start the second chat instance

python chat_app.py -p 8001 -n Bob

Step 3: Connect Bob to Alice

In Bob's chat window:

/add Alice 192.168.1.100:8000

Step 4: Verify the connection

In both chat windows:

/list

Step 5: Exchange messages

In Alice's window (broadcasts to all connected peers):

Hello, everyone!

Or send a private message to Bob:

/msg Bob Hello, Bob!

Step 6: Save the peer list for future use

/save my_peers.json

Later, you can load this configuration:

/load my_peers.json

How It Works

The implementation uses UDP hole punching to establish peer-to-peer connections through NATs. Each peer establishes and maintains connections with multiple other peers using a single UDP socket.

Messages are encrypted using AES-GCM for security and include sequence numbers and acknowledgments for reliability. The implementation handles packet reordering, retransmission, and connection management.

Testing

Run the tests:

python -m unittest test_multi_holepunch.py
python -m unittest test_multi_holepunch_protocol.py

License

MIT