__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_method: the implemented Authorization method. It will
be verified against Authorization headers. Subclasses must define this
attribute.
@type authorization_method: 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):
"""Try to authenticate a request. The Authorization header is examined
and checked agains the L{authorization_method} before being passed to
this method. This method must either raise an AuthenticationRequired
instance or return a dictionary explaining what was successfully
authenticated.
@type auth: str
@param auth: is the part of the Authorization header after the method
@type environ: {str: object}
@param environ: is the environment passed with a WSGI request
@rtype: {str: object}
@returns: a dictionary that provides a key "user" listing the
authenticated username as a string. It may also provide the key
"outheaders" with a [(str, str)] value to extend the response
headers.
@raises AuthenticationRequired: if the authentication was unsuccessful
"""
raise NotImplementedError
def __call__(self, environ, start_response):
"""wsgi interface
@type environ: {str: object}
"""
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)
result = self.authenticate(rest, environ)
except AuthenticationRequired as exc:
return self.authorization_required(environ, start_response, exc)
assert isinstance(result, dict)
assert "user" in result
environ["REMOTE_USER"] = result["user"]
if "outheaders" in result:
def modified_start_response(status, headers, exc_info=None):
assert isinstance(headers, list)
headers.extend(result["outheaders"])
return start_response(status, headers, exc_info)
else:
modified_start_response = start_response
return self.app(environ, modified_start_response)
def www_authenticate(self, exception):
"""Generates a WWW-Authenticate header. Subclasses must implement this
method.
@type exception: L{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: L{AuthenticationRequired}
@param exception: reason for the authentication failure
"""
status = "401 Authorization required"
html = b"401 Authorization required" \
b"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]