pync For Python Developers

There are two main objects of interest when using pync in your own Python scripts: the pync function and the Netcat class.

Running the pync function

Running the pync function is similar to running pync from the command-line. It will run a given string of arguments and return an integer exit status value once finished.

The pync function also takes a few more keyword arguments: stdin, stdout and stderr.

By default, these arguments point to the console for input and output.

You can pass your own file-like objects to these keyword arguments to control where the data gets read from and written to.

Send a GET request to an HTTP server

# pync_http_get.py
import io
import sys

from pync import pync

# io.BytesIO turns the GET request bytes string into a file-like
# object for the pync function.
request = io.BytesIO(b'GET / HTTP/1.0\r\n\r\n')

# pync reads and writes bytes, so be sure to open files in
# binary mode.
with open('http.response', 'wb') as response:
    status = pync('-q -1 host.example.com 80', stdin=request, stdout=response)

sys.exit(status)

This example sends a GET request string to a web server and saves the response to a file.

Creating a Netcat instance

Under the hood, the pync function creates a custom Netcat class and handles any exceptions that may occur, printing them to stderr.

If you would like more control over exception handling or maybe you’d like to customize your own Netcat, you can use the Netcat class.

Send a GET request to an HTTP server

# netcat_http_get.py
import io
from pync import Netcat

# io.BytesIO turns the GET request byte string into a file-like
# object for the Netcat class.
request = io.BytesIO(b'GET / HTTP/1.0\r\n\r\n')

# Netcat reads and writes bytes so be sure to open files in
# binary mode.
response = open('http.response', 'wb')
nc = Netcat('host.example.com', 80,
    q=-1,
    stdin=request,
    stdout=response,
)

try:
    nc.readwrite()
finally:
    response.close()
    nc.close()

As before when using the pync function, this sends a GET request to a web server and saves the response to a file.