CSP.py

Native Python, async-friendly implementation of Cubesat Space Protocol.

Features

• Python friendly async API
• Sockets and connections
• Interfaces
  • CAN Fragmentation Protocol v1 (compatible with https://github.com/libcsp/libcsp)
  • CAN Fragmentation Protocol v2 (compatible with https://github.com/libcsp/libcsp)
  • Serializing interface for easy intergration with other applications
  • Interface pair for in-memory testing between two nodes
• Socket options
  • CRC32 (compatible with https://github.com/libcsp/libcsp)
• CIDR Routing table
• Hooks for inspecting and/or modifying packets going through node
• System services
  • Ping

Missing features compared to libcsp

• RDP
• Packet flags
  • HMAC
• Remaining system sevices: uptime, reboot/shutdown, process list, memory free query, CSP Management Protocol
• Simple fragmentation protocol

When to use over libcsp?

• Easy use (pure Python library, no native dependencies)
• Testing
  • csp-py allows to start and tear down entire node within single test without leaking anything between tests
• Async API
  • Use asyncio to run communication, with gracefully handled timeouts and cancellations

Usage

1. Install package using pip

   user$ pip install cubesat-space-protocol-py
   

2. Create node:

   import csp_py
   
   node = csp_py.CspNode()
   

3. Add interface

   from csp_py.interfaces.serializing_interface import CspSerializingInterface
   
   async def capture_frame(frame: bytes) -> None:
       # TODO: frame contains entire serialized packet including header
       # send it over some communication channel
       pass
   
   async def handle_incoming_frames(iface: CspSerializingInterface) -> None:
       while True:
           # TODO: fetch frame from communication channel
           frame: bytes = await recv_frame()
           await iface.on_incoming_frame(frame)
   
   iface = CspSerializingInterface(capture_frame)
   # TODO: make sure addresses are correct
   node.router.add_interface(iface, address=1, netmask_bits=10)
   asyncio.create_task(handle_incoming_frames(iface))
   

4. Start router task

   router_task = asyncio.create_task(node.router.arun())
   

5. Use sockets

   connection = await node.connect(dst=0, port=20)
   await connection.send(b'Hello, world!')
   response = await connection.recv()
   print(f'Got response: {response.data}')
   

6. Stop router

   router_task.cancel()
   await router_task