gossh-python

This library binds crypto/ssh for use in Python3 using gopy.

Versions

All versions 1.0.0 and up support Python 3 only! If you need Python 2 support, check out the following:

• https://github.com/ftpsolutions/gossh-python/tree/v0.91
• https://pypi.org/project/gossh-python/0.91/

Concept

In the early days gopy was fairly limited in it's ability to track object allocation across the border of Go and Python.

As a result, our implementation is fairly naive- we only pass primitive types from Go to Python (nothing that comes by reference).

Session are managed entirely on the Go side and identified with an integer- here are a few function signatures to demonstrate:

• NewRPCSession(hostname, username, password string, port, timeout int) uint64
• RPCConnect(sessionID uint64) error
• RPCGetShell(sessionID uint64, terminal string, height, width int) error
• RPCRead(sessionID uint64, size int) (string, error)
• RPCWrite(sessionID uint64, data string) error
• RPCClose(sessionID uint64) error

The functions that return complex data do so in a special JSON-based format- at this point gopy does it's magic and those functions are made available to Python.

We then have RPCSession abstraction on the Python side that pulls things together in a class for convenience (saving you need the to keep track of the identifiers and handling deserialisation).

Weird gotchas

We're building for Python3 and we use a python-config script for Python3 however we're using a python.pc file from Python2.

I dunno why this has to be this way, but it's the only way I can get the C Python API GIL lock/unlock calls to be available to Go (C.PyEval_SaveThread() and C.PyEval_RestoreThread(tState)).

So if you're wondering why Python2 still comes into it here and there- that's why. Doesn't seem to cause any problems.

Prerequisites

• MacOS
• CPython3.8+
• virtualenv
  • pip install virtualenv
• pkgconfig
  • brew install pkg-config
• Docker

Install (from PyPI)

python -m pip install gossh-python

Setup

virtualenv -p $(which python3) venv
source venv/bin/activate
./fix_venv.sh
pip install -r requirements-dev.txt

Build

source venv/bin/activate
./native_build.sh

If you're deep in the grind and want to iterate faster, you can invoke:

./native_build.sh fast

This skips the setup (assuming you've already done that).