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"""
Provides various authentication policies.
"""
from __future__ import unicode_literals
import base64
import binascii
from django.contrib.auth import authenticate, get_user_model
from django.middleware.csrf import CsrfViewMiddleware
from django.utils.six import text_type
from django.utils.translation import ugettext_lazy as _
from rest_framework import HTTP_HEADER_ENCODING, exceptions
def get_authorization_header(request):
"""
Return request's 'Authorization:' header, as a bytestring.
Hide some test client ickyness where the header can be unicode.
"""
auth = request.META.get('HTTP_AUTHORIZATION', b'')
if isinstance(auth, text_type):
# Work around django test client oddness
auth = auth.encode(HTTP_HEADER_ENCODING)
return auth
class CSRFCheck(CsrfViewMiddleware):
def _reject(self, request, reason):
# Return the failure reason instead of an HttpResponse
return reason
class BaseAuthentication(object):
"""
All authentication classes should extend BaseAuthentication.
"""
def authenticate(self, request):
"""
Authenticate the request and return a two-tuple of (user, token).
"""
raise NotImplementedError(".authenticate() must be overridden.")
def authenticate_header(self, request):
"""
Return a string to be used as the value of the `WWW-Authenticate`
header in a `401 Unauthenticated` response, or `None` if the
authentication scheme should return `403 Permission Denied` responses.
"""
pass
class BasicAuthentication(BaseAuthentication):
"""
HTTP Basic authentication against username/password.
"""
www_authenticate_realm = 'api'
def authenticate(self, request):
"""
Returns a `User` if a correct username and password have been supplied
using HTTP Basic authentication. Otherwise returns `None`.
"""
auth = get_authorization_header(request).split()
if not auth or auth[0].lower() != b'basic':
return None
if len(auth) == 1:
msg = _('Invalid basic header. No credentials provided.')
raise exceptions.AuthenticationFailed(msg)
elif len(auth) > 2:
msg = _('Invalid basic header. Credentials string should not contain spaces.')
raise exceptions.AuthenticationFailed(msg)
try:
auth_parts = base64.b64decode(auth[1]).decode(HTTP_HEADER_ENCODING).partition(':')
except (TypeError, UnicodeDecodeError, binascii.Error):
msg = _('Invalid basic header. Credentials not correctly base64 encoded.')
raise exceptions.AuthenticationFailed(msg)
userid, password = auth_parts[0], auth_parts[2]
return self.authenticate_credentials(userid, password, request)
def authenticate_credentials(self, userid, password, request=None):
"""
Authenticate the userid and password against username and password
with optional request for context.
"""
credentials = {
get_user_model().USERNAME_FIELD: userid,
'password': password
}
user = authenticate(request=request, **credentials)
if user is None:
raise exceptions.AuthenticationFailed(_('Invalid username/password.'))
if not user.is_active:
raise exceptions.AuthenticationFailed(_('User inactive or deleted.'))
return (user, None)
def authenticate_header(self, request):
return 'Basic realm="%s"' % self.www_authenticate_realm
class SessionAuthentication(BaseAuthentication):
"""
Use Django's session framework for authentication.
"""
def authenticate(self, request):
"""
Returns a `User` if the request session currently has a logged in user.
Otherwise returns `None`.
"""
# Get the session-based user from the underlying HttpRequest object
user = getattr(request._request, 'user', None)
# Unauthenticated, CSRF validation not required
if not user or not user.is_active:
return None
self.enforce_csrf(request)
# CSRF passed with authenticated user
return (user, None)
def enforce_csrf(self, request):
"""
Enforce CSRF validation for session based authentication.
"""
check = CSRFCheck()
# populates request.META['CSRF_COOKIE'], which is used in process_view()
check.process_request(request)
reason = check.process_view(request, None, (), {})
if reason:
# CSRF failed, bail with explicit error message
raise exceptions.PermissionDenied('CSRF Failed: %s' % reason)
class TokenAuthentication(BaseAuthentication):
"""
Simple token based authentication.
Clients should authenticate by passing the token key in the "Authorization"
HTTP header, prepended with the string "Token ". For example:
Authorization: Token 401f7ac837da42b97f613d789819ff93537bee6a
"""
keyword = 'Token'
model = None
def get_model(self):
if self.model is not None:
return self.model
from rest_framework.authtoken.models import Token
return Token
"""
A custom token model may be used, but must have the following properties.
* key -- The string identifying the token
* user -- The user to which the token belongs
"""
def authenticate(self, request):
auth = get_authorization_header(request).split()
if not auth or auth[0].lower() != self.keyword.lower().encode():
return None
if len(auth) == 1:
msg = _('Invalid token header. No credentials provided.')
raise exceptions.AuthenticationFailed(msg)
elif len(auth) > 2:
msg = _('Invalid token header. Token string should not contain spaces.')
raise exceptions.AuthenticationFailed(msg)
try:
token = auth[1].decode()
except UnicodeError:
msg = _('Invalid token header. Token string should not contain invalid characters.')
raise exceptions.AuthenticationFailed(msg)
return self.authenticate_credentials(token)
def authenticate_credentials(self, key):
model = self.get_model()
try:
token = model.objects.select_related('user').get(key=key)
except model.DoesNotExist:
raise exceptions.AuthenticationFailed(_('Invalid token.'))
if not token.user.is_active:
raise exceptions.AuthenticationFailed(_('User inactive or deleted.'))
return (token.user, token)
def authenticate_header(self, request):
return self.keyword
class RemoteUserAuthentication(BaseAuthentication):
"""
REMOTE_USER authentication.
To use this, set up your web server to perform authentication, which will
set the REMOTE_USER environment variable. You will need to have
'django.contrib.auth.backends.RemoteUserBackend in your
AUTHENTICATION_BACKENDS setting
"""
# Name of request header to grab username from. This will be the key as
# used in the request.META dictionary, i.e. the normalization of headers to
# all uppercase and the addition of "HTTP_" prefix apply.
header = "REMOTE_USER"
def authenticate(self, request):
user = authenticate(remote_user=request.META.get(self.header))
if user and user.is_active:
return (user, None)