bareASGI-sspi

ASGI middleware for the bareASGI framework providing SSPI authentication on Windows.

The implementation uses the pyspnego package.

There is also a generic ASGI server middleware implementation in the package jetblack-asgi-sspi.

Installation

Install from the pie store.

pip install bareasgi-sspi

Usage

The following program uses the Hypercorn ASGI server.

import asyncio
import logging
from typing import Optional

from bareasgi import Application, HttpRequest, HttpResponse
from bareutils import text_writer
from hypercorn import Config
from hypercorn.asyncio import serve

from bareasgi_sspi import add_sspi_middleware, sspi_details

# A callback to display the results of the SSPI middleware.
async def http_request_callback(request: HttpRequest) -> HttpResponse:
    # Get the details from the request context request['sspi']. Note if
    # authentication failed this might be absent or empty.
    sspi = sspi_details(request)
    client_principal = (
        sspi['client_principal']
        if sspi is not None
        else 'unknown'
    )
    return HttpResponse(
        200,
        [(b'content-type', b'text/plain')],
        text_writer(f"Authenticated as '{client_principal}'")
    )


async def main_async():
    # Make the ASGI application using the middleware.
    app = Application()
    app.http_router.add({'GET'}, '/', http_request_callback)

    # Add the middleware. Change the protocol from Negotiate to NTLM,
    # and allow unauthenticated requests to pass through.
    add_sspi_middleware(
        app,
        protocol=b'NTLM',
        forbid_unauthenticated=False
    )

    # Start the ASGI server.
    config = Config()
    config.bind = ['localhost:9023']
    await serve(app, config)

if __name__ == '__main__':
    logging.basicConfig(level=logging.DEBUG)
    asyncio.run(main_async())

Arguments

Optional arguments include:

• protocol (bytes): Either b"Negotiate" or b"NTLM" (for systems not part of a domain).
• service (str): The SPN service. Defaults to "HTTP".
• hostname (str, optional): The hostname. Defaults to he result of socket.gethostname().
• session_duration (timedelta, optional): The duration of a session. Defaults to 1 hour.
• forbid_unauthenticated (bool): If true, and authentication fails, send 403 (Forbidden). Otherwise handle the request unauthenticated.
• context_key (str, optional): The key used in the request context. Defaults to sspi.
• whitelist (Sequence[str], optional): Paths not to authenticate. Defaults to ().

Results

If the authentication is successful the SSPI details are added to the context dictionary of the HttpRequest object with the key "sspi" (if not overridden). There is a helper method sspi_details for this.

The following properties are set:

• "client_principal" (str): The username of the client.
• "negotiated_protocol" (str): The negotiated protocol.
• "protocol" (str): The requested protocol.
• "spn" (str): The SPN of the server.