Source code for cherrypy.lib.httpauth

"""
This module defines functions to implement HTTP Digest Authentication
(:rfc:`2617`).
This has full compliance with 'Digest' and 'Basic' authentication methods. In
'Digest' it supports both MD5 and MD5-sess algorithms.

Usage:
    First use 'doAuth' to request the client authentication for a
    certain resource. You should send an httplib.UNAUTHORIZED response to the
    client so he knows he has to authenticate itself.

    Then use 'parseAuthorization' to retrieve the 'auth_map' used in
    'checkResponse'.

    To use 'checkResponse' you must have already verified the password
    associated with the 'username' key in 'auth_map' dict. Then you use the
    'checkResponse' function to verify if the password matches the one sent
    by the client.

SUPPORTED_ALGORITHM - list of supported 'Digest' algorithms
SUPPORTED_QOP - list of supported 'Digest' 'qop'.
"""

import time
from hashlib import md5

from six.moves.urllib.request import parse_http_list, parse_keqv_list

from cherrypy._cpcompat import (
    base64_decode, ntob,
)


__version__ = 1, 0, 1
__author__ = 'Tiago Cogumbreiro <cogumbreiro@users.sf.net>'
__credits__ = """
    Peter van Kampen for its recipe which implement most of Digest
    authentication:
    http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/302378
"""

__license__ = """
Copyright (c) 2005, Tiago Cogumbreiro <cogumbreiro@users.sf.net>
All rights reserved.

Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:

    * Redistributions of source code must retain the above copyright notice,
      this list of conditions and the following disclaimer.
    * Redistributions in binary form must reproduce the above copyright notice,
      this list of conditions and the following disclaimer in the documentation
      and/or other materials provided with the distribution.
    * Neither the name of Sylvain Hellegouarch nor the names of his
      contributors may be used to endorse or promote products derived from
      this software without specific prior written permission.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE
FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
"""

__all__ = ('digestAuth', 'basicAuth', 'doAuth', 'checkResponse',
           'parseAuthorization', 'SUPPORTED_ALGORITHM', 'md5SessionKey',
           'calculateNonce', 'SUPPORTED_QOP')

##########################################################################

MD5 = 'MD5'
MD5_SESS = 'MD5-sess'
AUTH = 'auth'
AUTH_INT = 'auth-int'

SUPPORTED_ALGORITHM = (MD5, MD5_SESS)
SUPPORTED_QOP = (AUTH, AUTH_INT)

##########################################################################
# doAuth
#
DIGEST_AUTH_ENCODERS = {
    MD5: lambda val: md5(ntob(val)).hexdigest(),
    MD5_SESS: lambda val: md5(ntob(val)).hexdigest(),
    #    SHA: lambda val: sha.new(ntob(val)).hexdigest (),
}


[docs]def calculateNonce(realm, algorithm=MD5): """This is an auxaliary function that calculates 'nonce' value. It is used to handle sessions.""" global SUPPORTED_ALGORITHM, DIGEST_AUTH_ENCODERS assert algorithm in SUPPORTED_ALGORITHM try: encoder = DIGEST_AUTH_ENCODERS[algorithm] except KeyError: raise NotImplementedError('The chosen algorithm (%s) does not have ' 'an implementation yet' % algorithm) return encoder('%d:%s' % (time.time(), realm))
[docs]def digestAuth(realm, algorithm=MD5, nonce=None, qop=AUTH): """Challenges the client for a Digest authentication.""" global SUPPORTED_ALGORITHM, DIGEST_AUTH_ENCODERS, SUPPORTED_QOP assert algorithm in SUPPORTED_ALGORITHM assert qop in SUPPORTED_QOP if nonce is None: nonce = calculateNonce(realm, algorithm) return 'Digest realm="%s", nonce="%s", algorithm="%s", qop="%s"' % ( realm, nonce, algorithm, qop )
[docs]def basicAuth(realm): """Challengenes the client for a Basic authentication.""" assert '"' not in realm, "Realms cannot contain the \" (quote) character." return 'Basic realm="%s"' % realm
[docs]def doAuth(realm): """'doAuth' function returns the challenge string b giving priority over Digest and fallback to Basic authentication when the browser doesn't support the first one. This should be set in the HTTP header under the key 'WWW-Authenticate'.""" return digestAuth(realm) + ' ' + basicAuth(realm)
########################################################################## # Parse authorization parameters # def _parseDigestAuthorization(auth_params): # Convert the auth params to a dict items = parse_http_list(auth_params) params = parse_keqv_list(items) # Now validate the params # Check for required parameters required = ['username', 'realm', 'nonce', 'uri', 'response'] for k in required: if k not in params: return None # If qop is sent then cnonce and nc MUST be present if 'qop' in params and not ('cnonce' in params and 'nc' in params): return None # If qop is not sent, neither cnonce nor nc can be present if ('cnonce' in params or 'nc' in params) and 'qop' not in params: return None return params def _parseBasicAuthorization(auth_params): username, password = base64_decode(auth_params).split(':', 1) return {'username': username, 'password': password} AUTH_SCHEMES = { # noqa: E305 'basic': _parseBasicAuthorization, 'digest': _parseDigestAuthorization, }
[docs]def parseAuthorization(credentials): """parseAuthorization will convert the value of the 'Authorization' key in the HTTP header to a map itself. If the parsing fails 'None' is returned. """ global AUTH_SCHEMES auth_scheme, auth_params = credentials.split(' ', 1) auth_scheme = auth_scheme.lower() parser = AUTH_SCHEMES[auth_scheme] params = parser(auth_params) if params is None: return assert 'auth_scheme' not in params params['auth_scheme'] = auth_scheme return params
########################################################################## # Check provided response for a valid password #
[docs]def md5SessionKey(params, password): """ If the "algorithm" directive's value is "MD5-sess", then A1 [the session key] is calculated only once - on the first request by the client following receipt of a WWW-Authenticate challenge from the server. This creates a 'session key' for the authentication of subsequent requests and responses which is different for each "authentication session", thus limiting the amount of material hashed with any one key. Because the server need only use the hash of the user credentials in order to create the A1 value, this construction could be used in conjunction with a third party authentication service so that the web server would not need the actual password value. The specification of such a protocol is beyond the scope of this specification. """ keys = ('username', 'realm', 'nonce', 'cnonce') params_copy = {} for key in keys: params_copy[key] = params[key] params_copy['algorithm'] = MD5_SESS return _A1(params_copy, password)
def _A1(params, password): algorithm = params.get('algorithm', MD5) H = DIGEST_AUTH_ENCODERS[algorithm] if algorithm == MD5: # If the "algorithm" directive's value is "MD5" or is # unspecified, then A1 is: # A1 = unq(username-value) ":" unq(realm-value) ":" passwd return '%s:%s:%s' % (params['username'], params['realm'], password) elif algorithm == MD5_SESS: # This is A1 if qop is set # A1 = H( unq(username-value) ":" unq(realm-value) ":" passwd ) # ":" unq(nonce-value) ":" unq(cnonce-value) h_a1 = H('%s:%s:%s' % (params['username'], params['realm'], password)) return '%s:%s:%s' % (h_a1, params['nonce'], params['cnonce']) def _A2(params, method, kwargs): # If the "qop" directive's value is "auth" or is unspecified, then A2 is: # A2 = Method ":" digest-uri-value qop = params.get('qop', 'auth') if qop == 'auth': return method + ':' + params['uri'] elif qop == 'auth-int': # If the "qop" value is "auth-int", then A2 is: # A2 = Method ":" digest-uri-value ":" H(entity-body) entity_body = kwargs.get('entity_body', '') H = kwargs['H'] return '%s:%s:%s' % ( method, params['uri'], H(entity_body) ) else: raise NotImplementedError("The 'qop' method is unknown: %s" % qop) def _computeDigestResponse(auth_map, password, method='GET', A1=None, **kwargs): """ Generates a response respecting the algorithm defined in RFC 2617 """ params = auth_map algorithm = params.get('algorithm', MD5) H = DIGEST_AUTH_ENCODERS[algorithm] KD = lambda secret, data: H(secret + ':' + data) qop = params.get('qop', None) H_A2 = H(_A2(params, method, kwargs)) if algorithm == MD5_SESS and A1 is not None: H_A1 = H(A1) else: H_A1 = H(_A1(params, password)) if qop in ('auth', 'auth-int'): # If the "qop" value is "auth" or "auth-int": # request-digest = <"> < KD ( H(A1), unq(nonce-value) # ":" nc-value # ":" unq(cnonce-value) # ":" unq(qop-value) # ":" H(A2) # ) <"> request = '%s:%s:%s:%s:%s' % ( params['nonce'], params['nc'], params['cnonce'], params['qop'], H_A2, ) elif qop is None: # If the "qop" directive is not present (this construction is # for compatibility with RFC 2069): # request-digest = # <"> < KD ( H(A1), unq(nonce-value) ":" H(A2) ) > <"> request = '%s:%s' % (params['nonce'], H_A2) return KD(H_A1, request) def _checkDigestResponse(auth_map, password, method='GET', A1=None, **kwargs): """This function is used to verify the response given by the client when he tries to authenticate. Optional arguments: entity_body - when 'qop' is set to 'auth-int' you MUST provide the raw data you are going to send to the client (usually the HTML page. request_uri - the uri from the request line compared with the 'uri' directive of the authorization map. They must represent the same resource (unused at this time). """ if auth_map['realm'] != kwargs.get('realm', None): return False response = _computeDigestResponse( auth_map, password, method, A1, **kwargs) return response == auth_map['response'] def _checkBasicResponse(auth_map, password, method='GET', encrypt=None, **kwargs): # Note that the Basic response doesn't provide the realm value so we cannot # test it pass_through = lambda password, username=None: password encrypt = encrypt or pass_through try: candidate = encrypt(auth_map['password'], auth_map['username']) except TypeError: # if encrypt only takes one parameter, it's the password candidate = encrypt(auth_map['password']) return candidate == password AUTH_RESPONSES = { # noqa: E305 'basic': _checkBasicResponse, 'digest': _checkDigestResponse, }
[docs]def checkResponse(auth_map, password, method='GET', encrypt=None, **kwargs): """'checkResponse' compares the auth_map with the password and optionally other arguments that each implementation might need. If the response is of type 'Basic' then the function has the following signature:: checkBasicResponse(auth_map, password) -> bool If the response is of type 'Digest' then the function has the following signature:: checkDigestResponse(auth_map, password, method='GET', A1=None) -> bool The 'A1' argument is only used in MD5_SESS algorithm based responses. Check md5SessionKey() for more info. """ checker = AUTH_RESPONSES[auth_map['auth_scheme']] return checker(auth_map, password, method=method, encrypt=encrypt, **kwargs)