__all__ = []
class AuthenticationRequired(Exception):
"""
Internal Exception class that is thrown inside L{AuthenticationMiddleware},
but not visible to other code.
"""
class ProtocolViolation(AuthenticationRequired):
pass
class AuthenticationMiddleware:
"""Base class for HTTP authorization schemes.
@cvar authorization_required: the implemented Authorization method. It will
be verified against Authorization headers. Subclasses must define this
attribute.
@type authorization_required: str
"""
authorization_method = None
def __init__(self, app):
"""
@param app: is a WSGI application.
"""
assert self.authorization_method is not None
self.app = app
def authenticate(self, auth, environ, start_response):
"""
@type auth: str
@param auth: is the part of the Authorization header after the method
"""
raise NotImplementedError
def __call__(self, environ, start_response):
assert isinstance(environ, dict)
try:
try:
auth = environ["HTTP_AUTHORIZATION"]
except KeyError:
raise AuthenticationRequired("no Authorization header found")
try:
method, rest = auth.split(' ', 1)
except ValueError:
method, rest = auth, ""
if method.lower() != self.authorization_method:
raise AuthenticationRequired(
"authorization method not implemented: %r" % method)
return self.authenticate(rest, environ, start_response)
except AuthenticationRequired, exc:
return self.authorization_required(environ, start_response, exc)
def www_authenticate(self, exception):
"""Generates a WWW-Authenticate header. Subclasses must implement this
method.
@type exception: AuthenticationRequired
@param exception: reason for generating the header
@rtype: (str, str)
@returns: the header as (part_before_colon, part_after_colon)
"""
raise NotImplementedError
def authorization_required(self, environ, start_response, exception):
"""Generate an error page after failed authentication. Apart from the
exception parameter, this method behaves like a WSGI application.
@type exception: AuthenticationRequired
@param exception: reason for the authentication failure
"""
status = "401 Authorization required"
html = "401 Authorization required" \
"401 Authorization required
"
headers = [("Content-Type", "text/html"),
self.www_authenticate(exception),
("Content-Length", str(len(html)))]
start_response(status, headers)
if environ["REQUEST_METHOD"].upper() == "HEAD":
return []
return [html]