Error parsing OSPF LSDB output: host bits set

[rbeumer]

I was testing with the lastest docker image and uploading an OSPF LSDB. The uploading works for an IOS-XR LSDB but when I am testing the output from a Cisco IOS LSDB it trows an internal server error. The Flask logs show the following error:

[2021-08-04 08:54:41 +0000] [13] [ERROR] Error handling request /upload-ospf-lsdb
Traceback (most recent call last):
  File "/usr/local/lib/python3.6/site-packages/gunicorn/workers/sync.py", line 134, in handle
    self.handle_request(listener, req, client, addr)
  File "/usr/local/lib/python3.6/site-packages/gunicorn/workers/sync.py", line 175, in handle_request
    respiter = self.wsgi(environ, resp.start_response)
  File "/usr/local/lib/python3.6/site-packages/connexion/apps/abstract.py", line 249, in __call__
    return self.app(environ, start_response)
  File "/usr/local/lib/python3.6/site-packages/flask/app.py", line 2464, in __call__
    return self.wsgi_app(environ, start_response)
  File "/usr/local/lib/python3.6/site-packages/flask/app.py", line 2450, in wsgi_app
    response = self.handle_exception(e)
  File "/usr/local/lib/python3.6/site-packages/flask/app.py", line 1867, in handle_exception
    reraise(exc_type, exc_value, tb)
  File "/usr/local/lib/python3.6/site-packages/flask/_compat.py", line 39, in reraise
    raise value
  File "/usr/local/lib/python3.6/site-packages/flask/app.py", line 2447, in wsgi_app
    response = self.full_dispatch_request()
  File "/usr/local/lib/python3.6/site-packages/flask/app.py", line 1952, in full_dispatch_request
    rv = self.handle_user_exception(e)
  File "/usr/local/lib/python3.6/site-packages/flask/app.py", line 1821, in handle_user_exception
    reraise(exc_type, exc_value, tb)
  File "/usr/local/lib/python3.6/site-packages/flask/_compat.py", line 39, in reraise
    raise value
  File "/usr/local/lib/python3.6/site-packages/flask/app.py", line 1950, in full_dispatch_request
    rv = self.dispatch_request()
  File "/usr/local/lib/python3.6/site-packages/flask/app.py", line 1936, in dispatch_request
    return self.view_functions[rule.endpoint](**req.view_args)
  File "routes.pyx", line 2063, in routes.upload_file
  File "Helpers.pyx", line 1883, in Helpers.ParsingHelper.doParseLsdbAndBuildGraph
  File "Helpers.pyx", line 1274, in Helpers.ParsingHelper.parse_router_lsa
  File "/usr/local/lib/python3.6/ipaddress.py", line 1519, in __init__
    raise ValueError('%s has host bits set' % self)
ValueError: x.x.x.x/31 has host bits set

The IP address has obiously been obfuscated.

When I check the LSDB output the IP address mentioned in the error is part of a type 1 router LSA. It is first part of a /31 point to point link and also mentioned als a stub network.

    Link connected to: another Router (point-to-point)
     (Link ID) Neighboring Router ID: x.x.x.x
     (Link Data) Router Interface address: x.x.x.x <== IP address with the /31 mask mentioned in the error
      Number of MTID metrics: 0
       TOS 0 Metrics: 1

    Link connected to: a Stub Network
     (Link ID) Network/subnet number: x.x.x.x <== IP address with the /31 mask mentioned in the error
     (Link Data) Network Mask: 255.255.255.254
      Number of MTID metrics: 0
       TOS 0 Metrics: 1

The Python IP address library is throwing this error because the address mentioned is not the network address it seems, though with a /31 you won't have a dedicated network address. In my case it is the second address in the /31.

I can't check the code to see why and how the IP address is being checked by the ipaddress module so I can't speculate on how to solve it. Would you be willing to add the code to this repository so others might help solving this issue?

[Vadims06]

Hi @rbeumer, thank you for your feedback and for such deep investigation. I met cases when OSPF use non-network addresses and probably my implemented logic doesn't cover all cases) I will try to recreate the issue, fix, release it next week.

[Vadims06]

Hi @rbeumer, the fix has been released in v2.21.1. Please make a docker-compose pull and provide me an update.

[rbeumer]

Thanks! The fix seems to work, uploading the LSDB output is now working without any errors, also no errors from the Flask container.

[Vadims06]

fixed