Binding problem

[tuliocg]

Hi folks,

I'm having an issue regarding to the binding that the module is using, it seems that by default its set to Redirect but my provider is expecting POST as below:

`Environment:

Request Method: GET
Request URL: http://localhost:8000/login/?next=/

Django Version: 3.1.7
Python Version: 3.8.8
Installed Applications:
['django.contrib.admin',
'django.contrib.auth',
'django.contrib.contenttypes',
'django.contrib.sessions',
'django.contrib.messages',
'django.contrib.staticfiles',
'django_extensions',
'interlake_uploader',
'django_saml2_auth']
Installed Middleware:
['django.middleware.security.SecurityMiddleware',
'django.contrib.sessions.middleware.SessionMiddleware',
'django.middleware.common.CommonMiddleware',
'django.middleware.csrf.CsrfViewMiddleware',
'django.contrib.auth.middleware.AuthenticationMiddleware',
'django.contrib.messages.middleware.MessageMiddleware',
'django.middleware.clickjacking.XFrameOptionsMiddleware']

Traceback (most recent call last):
File "/usr/local/lib/python3.8/site-packages/django/core/handlers/exception.py", line 47, in inner
response = get_response(request)
File "/usr/local/lib/python3.8/site-packages/django/core/handlers/base.py", line 181, in _get_response
response = wrapped_callback(request, *callback_args, **callback_kwargs)
File "/usr/local/lib/python3.8/site-packages/django_saml2_auth/views.py", line 243, in signin
_, info = saml_client.prepare_for_authenticate()
File "/usr/local/lib/python3.8/site-packages/saml2/client.py", line 72, in prepare_for_authenticate
reqid, negotiated_binding, info = self.prepare_for_negotiated_authenticate(
File "/usr/local/lib/python3.8/site-packages/saml2/client.py", line 137, in prepare_for_negotiated_authenticate
destination = self._sso_location(entityid, binding)
File "/usr/local/lib/python3.8/site-packages/saml2/client_base.py", line 235, in _sso_location
srvs = self.metadata.single_sign_on_service(list(eids.keys())[0], binding)
File "/usr/local/lib/python3.8/site-packages/saml2/mdstore.py", line 1190, in single_sign_on_service
return self.service(entity_id, "idpsso_descriptor",
File "/usr/local/lib/python3.8/site-packages/saml2/mdstore.py", line 1147, in service
raise UnsupportedBinding(binding)

Exception Type: UnsupportedBinding at /login/
Exception Value: urn:oasis:names:tc:SAML:2.0:bindings:HTTP-Redirect
`

I was able to solve this issue replacing the binding variable on mdstore.py from Redirect to POST, but it felt wrong to do so, is there any other way that I can change this setting ?