root / lib / http / auth.py @ 2287b920
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# Copyright (C) 2007, 2008 Google Inc.
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#
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# This program is free software; you can redistribute it and/or modify
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# it under the terms of the GNU General Public License as published by
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# the Free Software Foundation; either version 2 of the License, or
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# (at your option) any later version.
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#
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# This program is distributed in the hope that it will be useful, but
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# WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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# General Public License for more details.
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#
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# You should have received a copy of the GNU General Public License
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# along with this program; if not, write to the Free Software
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# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
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# 02110-1301, USA.
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"""HTTP authentication module.
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"""
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import logging |
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import re |
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import base64 |
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import binascii |
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from ganeti import compat |
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from ganeti import http |
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from cStringIO import StringIO |
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# Digest types from RFC2617
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HTTP_BASIC_AUTH = "Basic"
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HTTP_DIGEST_AUTH = "Digest"
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# Not exactly as described in RFC2616, section 2.2, but good enough
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_NOQUOTE = re.compile(r"^[-_a-z0-9]+$", re.I)
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def _FormatAuthHeader(scheme, params): |
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"""Formats WWW-Authentication header value as per RFC2617, section 1.2
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@type scheme: str
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@param scheme: Authentication scheme
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@type params: dict
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@param params: Additional parameters
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@rtype: str
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@return: Formatted header value
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"""
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buf = StringIO() |
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buf.write(scheme) |
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for name, value in params.iteritems(): |
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buf.write(" ")
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buf.write(name) |
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buf.write("=")
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if _NOQUOTE.match(value):
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buf.write(value) |
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else:
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buf.write("\"")
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# TODO: Better quoting
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buf.write(value.replace("\"", "\\\"")) |
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buf.write("\"")
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return buf.getvalue()
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class HttpServerRequestAuthentication(object): |
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# Default authentication realm
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AUTH_REALM = "Unspecified"
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# Schemes for passwords
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_CLEARTEXT_SCHEME = "{CLEARTEXT}"
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_HA1_SCHEME = "{HA1}"
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def GetAuthRealm(self, req): |
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"""Returns the authentication realm for a request.
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May be overridden by a subclass, which then can return different realms for
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different paths.
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@type req: L{http.server._HttpServerRequest}
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@param req: HTTP request context
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@rtype: string
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@return: Authentication realm
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"""
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# today we don't have per-request filtering, but we might want to
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# add it in the future
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# pylint: disable-msg=W0613
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return self.AUTH_REALM |
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def AuthenticationRequired(self, req): |
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"""Determines whether authentication is required for a request.
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To enable authentication, override this function in a subclass and return
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C{True}. L{AUTH_REALM} must be set.
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@type req: L{http.server._HttpServerRequest}
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@param req: HTTP request context
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"""
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# Unused argument, method could be a function
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# pylint: disable-msg=W0613,R0201
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return False |
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def PreHandleRequest(self, req): |
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"""Called before a request is handled.
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@type req: L{http.server._HttpServerRequest}
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@param req: HTTP request context
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"""
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# Authentication not required, and no credentials given?
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if not (self.AuthenticationRequired(req) or |
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(req.request_headers and
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http.HTTP_AUTHORIZATION in req.request_headers)):
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return
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realm = self.GetAuthRealm(req)
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if not realm: |
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raise AssertionError("No authentication realm") |
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# Check "Authorization" header
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if self._CheckAuthorization(req): |
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# User successfully authenticated
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return
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# Send 401 Unauthorized response
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params = { |
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"realm": realm,
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} |
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# TODO: Support for Digest authentication (RFC2617, section 3).
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# TODO: Support for more than one WWW-Authenticate header with the same
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# response (RFC2617, section 4.6).
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headers = { |
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http.HTTP_WWW_AUTHENTICATE: _FormatAuthHeader(HTTP_BASIC_AUTH, params), |
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} |
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raise http.HttpUnauthorized(headers=headers)
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def _CheckAuthorization(self, req): |
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"""Checks 'Authorization' header sent by client.
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@type req: L{http.server._HttpServerRequest}
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@param req: HTTP request context
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@rtype: bool
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@return: Whether user is allowed to execute request
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"""
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credentials = req.request_headers.get(http.HTTP_AUTHORIZATION, None)
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if not credentials: |
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return False |
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# Extract scheme
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parts = credentials.strip().split(None, 2) |
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if len(parts) < 1: |
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# Missing scheme
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return False |
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# RFC2617, section 1.2: "[...] It uses an extensible, case-insensitive
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# token to identify the authentication scheme [...]"
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scheme = parts[0].lower()
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if scheme == HTTP_BASIC_AUTH.lower():
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# Do basic authentication
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if len(parts) < 2: |
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raise http.HttpBadRequest(message=("Basic authentication requires" |
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" credentials"))
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return self._CheckBasicAuthorization(req, parts[1]) |
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elif scheme == HTTP_DIGEST_AUTH.lower():
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# TODO: Implement digest authentication
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# RFC2617, section 3.3: "Note that the HTTP server does not actually need
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# to know the user's cleartext password. As long as H(A1) is available to
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# the server, the validity of an Authorization header may be verified."
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pass
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# Unsupported authentication scheme
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return False |
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def _CheckBasicAuthorization(self, req, in_data): |
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"""Checks credentials sent for basic authentication.
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@type req: L{http.server._HttpServerRequest}
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@param req: HTTP request context
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@type in_data: str
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@param in_data: Username and password encoded as Base64
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@rtype: bool
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@return: Whether user is allowed to execute request
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"""
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try:
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creds = base64.b64decode(in_data.encode('ascii')).decode('ascii') |
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except (TypeError, binascii.Error, UnicodeError): |
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logging.exception("Error when decoding Basic authentication credentials")
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return False |
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if ":" not in creds: |
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return False |
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(user, password) = creds.split(":", 1) |
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return self.Authenticate(req, user, password) |
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def Authenticate(self, req, user, password): |
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"""Checks the password for a user.
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This function MUST be overridden by a subclass.
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"""
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raise NotImplementedError() |
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def VerifyBasicAuthPassword(self, req, username, password, expected): |
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"""Checks the password for basic authentication.
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As long as they don't start with an opening brace ("E{lb}"), old passwords
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are supported. A new scheme uses H(A1) from RFC2617, where H is MD5 and A1
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consists of the username, the authentication realm and the actual password.
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@type req: L{http.server._HttpServerRequest}
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@param req: HTTP request context
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@type username: string
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@param username: Username from HTTP headers
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@type password: string
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@param password: Password from HTTP headers
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@type expected: string
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@param expected: Expected password with optional scheme prefix (e.g. from
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users file)
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"""
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# Backwards compatibility for old-style passwords without a scheme
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if not expected.startswith("{"): |
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expected = self._CLEARTEXT_SCHEME + expected
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# Check again, just to be sure
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if not expected.startswith("{"): |
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raise AssertionError("Invalid scheme") |
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scheme_end_idx = expected.find("}", 1) |
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# Ensure scheme has a length of at least one character
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if scheme_end_idx <= 1: |
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logging.warning("Invalid scheme in password for user '%s'", username)
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return False |
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scheme = expected[:scheme_end_idx + 1].upper()
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expected_password = expected[scheme_end_idx + 1:]
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# Good old plain text password
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if scheme == self._CLEARTEXT_SCHEME: |
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return password == expected_password
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# H(A1) as described in RFC2617
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if scheme == self._HA1_SCHEME: |
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realm = self.GetAuthRealm(req)
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if not realm: |
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# There can not be a valid password for this case
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raise AssertionError("No authentication realm") |
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expha1 = compat.md5_hash() |
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expha1.update("%s:%s:%s" % (username, realm, password))
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return (expected_password.lower() == expha1.hexdigest().lower())
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logging.warning("Unknown scheme '%s' in password for user '%s'",
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scheme, username) |
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return False |
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class PasswordFileUser(object): |
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"""Data structure for users from password file.
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"""
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def __init__(self, name, password, options): |
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self.name = name
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self.password = password
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self.options = options
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def ParsePasswordFile(contents): |
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"""Parses the contents of a password file.
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Lines in the password file are of the following format::
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<username> <password> [options]
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Fields are separated by whitespace. Username and password are mandatory,
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options are optional and separated by comma (','). Empty lines and comments
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('#') are ignored.
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@type file_name: str
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@param file_name: Path to password file
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@rtype: dict
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@return: Dictionary containing L{PasswordFileUser} instances
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"""
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users = {} |
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for line in contents.splitlines(): |
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line = line.strip() |
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# Ignore empty lines and comments
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if not line or line.startswith("#"): |
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continue
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parts = line.split(None, 2) |
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if len(parts) < 2: |
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# Invalid line
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continue
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name = parts[0]
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password = parts[1]
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# Extract options
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options = [] |
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if len(parts) >= 3: |
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for part in parts[2].split(","): |
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options.append(part.strip()) |
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users[name] = PasswordFileUser(name, password, options) |
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return users
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