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Imported Upstream version 4.6.2

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Mario Fetka
2021-07-25 07:32:41 +02:00
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# Authors:
# John Dennis <jdennis@redhat.com>
#
# Copyright (C) 2012 Red Hat
# see file 'COPYING' for use and warranty information
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program. If not, see <http://www.gnu.org/licenses/>.
import re
import datetime
import email.utils
from calendar import timegm
import six
# pylint: disable=import-error
from six.moves.urllib.parse import urlparse
# pylint: enable=import-error
'''
Core Python has two cookie libraries, Cookie.py targeted to server
side and cookielib.py targeted to client side. So why this module and
not use the standard libraries?
Cookie.py has some serious bugs, it cannot correctly parse the
HttpOnly, Secure, and Expires cookie attributes (more of a client side
need and not what it was designed for). Since we utilize those
attributes that makes Cookie.py a non-starter. Plus it's API awkard
and limited (we would have to build more on top of it).
The Cookie.py bug reports are:
http://bugs.python.org/issue3073
http://bugs.python.org/issue16611
cookielib.py has a lot of good featuress, a nice API and covers all
the relevant RFC's as well as actual practice in the field. However
cookielib.py is tighly integrated with urllib2 and it's not possible
to use most of the features of cookielib without simultaneously using
urllib2. Unfortunataely we only use httplib because of our dependency
on xmlrpc.client. Without urllib2 cookielib is a non-starter.
This module is a minimal implementation of Netscape cookies which
works equally well on either the client or server side. It's API is
easy to use with cookie attributes as class properties which can be
read or set easily. The Cookie object automatically converts Expires
and Max-Age attributes into datetime objects for easy time
comparision. Cookies in strings can easily be parsed, including
multiple cookies in the HTTP_COOKIE envionment variable.
The cookie RFC is silent on any escaping requirements for cookie
contents as such this module does not provide any automated support
escaping and unescapin.
'''
#-------------------------------------------------------------------------------
class Cookie(object):
'''
A Cookie object has the following attributes:
key
The name of the cookie
value
The value of the cookie
A Cookie also supports these predefined optional attributes. If an
optional attribute is not set on the cookie it's value is None.
domain
Restrict cookie usage to this domain
path
Restrict cookie usage to this path or below
expires
Cookie is invalid after this UTC timestamp
max_age
Cookie is invalid this many seconds in the future.
Has precedence over the expires attribute.
secure
Cookie should only be returned on secure (i.e. SSL/TLS)
connections.
httponly
Cookie is intended only for HTTP communication, it can
never be utilized in any other context (e.g. browser
Javascript).
See the documentation of get_expiration() for an explanation of
how the expires and max-age attributes interact as well as the
role of the timestamp attribute. Expiration values are stored as
datetime objects for easy manipulation and comparision.
There are two ways to instantiate a Cookie object. Either directly
via the constructor or by calling the class function parse() which
returns a list of Cookie objects found in a string.
To create a cookie to sent to a client:
Example:
cookie = Cookie('session', session_id,
domain=my_domain, path=mypath,
httponly=True, secure=True, expires=expiration)
headers.append(('Set-Cookie', str(cookie)))
To receive cookies from a request:
Example:
cookies = Cookie.parse(response.getheader('Set-Cookie'), request_url)
'''
class Expired(ValueError):
pass
class URLMismatch(ValueError):
pass
# regexp to split fields at a semi-colon
field_re = re.compile(r';\s*')
# regexp to locate a key/value pair
kv_pair_re = re.compile(r'^\s*([a-zA-Z0-9\!\#\$\%\&\'\*\+\-\.\^\_\`\|\~]+)\s*=\s*(.*?)\s*$', re.IGNORECASE)
# Reserved attribute names, maps from lower case protocol name to
# object attribute name
attrs = {'domain' : 'domain',
'path' : 'path',
'max-age' : 'max_age',
'expires' : 'expires',
'secure' : 'secure',
'httponly' : 'httponly'}
@classmethod
def datetime_to_time(cls, dt):
'''
Timestamps (timestamp & expires) are stored as datetime
objects in UTC. It's non-obvious how to convert a naive UTC
datetime into a unix time value (seconds since the epoch
UTC). That functionality is oddly missing from the datetime
and time modules. This utility provides that missing
functionality.
'''
# Use timegm from the calendar module
return timegm(dt.utctimetuple())
@classmethod
def datetime_to_string(cls, dt=None):
'''
Given a datetime object in UTC generate RFC 1123 date string.
'''
# Try to verify dt is specified as UTC. If utcoffset is not
# available we'll just have to assume the caller is using the
# correct timezone.
utcoffset = dt.utcoffset()
if utcoffset is not None and utcoffset.total_seconds() != 0.0:
raise ValueError("timezone is not UTC")
# Do not use strftime because it respects the locale, instead
# use the RFC 1123 formatting function which uses only English
return email.utils.formatdate(cls.datetime_to_time(dt), usegmt=True)
@classmethod
def parse_datetime(cls, s):
'''
Parse a RFC 822, RFC 1123 date string, return a datetime naive object in UTC.
'''
s = s.strip()
# Do not use strptime because it respects the locale, instead
# use the RFC 1123 parsing function which uses only English
try:
dt = datetime.datetime(*email.utils.parsedate(s)[0:6])
except Exception as e:
raise ValueError("unable to parse expires datetime '%s': %s" % (s, e))
return dt
@classmethod
def normalize_url_path(cls, url_path):
'''
Given a URL path, possibly empty, return a path consisting
only of directory components. The URL path must end with a
trailing slash for the last path element to be considered a
directory. Also the URL path must begin with a slash. Empty
input returns '/'.
Examples:
'' -> '/'
'/' -> '/'
'foo' -> '/'
'foo/' -> '/'
'/foo -> '/'
'/foo/' -> '/foo'
'/foo/bar' -> '/foo'
'/foo/bar/' -> '/foo/bar'
'''
url_path = url_path.lower()
if not url_path:
return '/'
if not url_path.startswith('/'):
return '/'
if url_path.count('/') <= 1:
return'/'
return url_path[:url_path.rindex('/')]
@classmethod
def parse(cls, cookie_string, request_url=None):
'''
Given a string containing one or more cookies (the
HTTP_COOKIES environment variable typically contains multiple
cookies) parse the string and return a list of Cookie objects
found in the string.
'''
# Our list of returned cookies
cookies = []
# Split the input string at semi-colon boundaries, we call this a
# field. A field may either be a single keyword or a key=value
# pair.
fields = Cookie.field_re.split(cookie_string)
# The input string may have multiple cookies inside it. This is
# common when the string comes from a HTTP_COOKIE environment
# variable. All the cookies will be contenated, separated by a
# semi-colon. Semi-colons are also the separator between
# attributes in a cookie.
#
# To distinguish between two adjacent cookies in a string we
# have to locate the key=value pair at the start of a
# cookie. Unfortunately cookies have attributes that also look
# like key/value pairs, the only way to distinguish a cookie
# attribute from a cookie is the fact the attribute names are
# reserved. A cookie attribute may either be a key/value pair
# or a single key (e.g. HttpOnly). As we scan the cookie we
# first identify the key=value (cookie name, cookie
# value). Then we continue scanning, if a bare key or
# key/value pair follows and is a known reserved keyword than
# that's an attribute belonging to the current cookie. As soon
# as we see a key/value pair whose key is not reserved we know
# we've found a new cookie. Bare keys (no value) can never
# start a new cookie.
# Iterate over all the fields and emit a new cookie whenever the
# next field is not a known attribute.
cookie = None
for field in fields:
match = Cookie.kv_pair_re.search(field)
if match:
key = match.group(1)
value = match.group(2)
# Double quoted value?
if value and value[0] == '"':
if value[-1] == '"':
value = value[1:-1]
else:
raise ValueError("unterminated quote in '%s'" % value)
kv_pair = True
else:
key = field
value = True # True because bare keys are boolean flags
kv_pair = False
is_attribute = key.lower() in Cookie.attrs
# First cookie found, create new cookie object
if cookie is None and kv_pair and not is_attribute:
cookie = Cookie(key, value)
# If start of new cookie then flush previous cookie and create
# a new one (it's a new cookie because it's a key/value pair
# whose key is not a reserved keyword).
elif cookie and kv_pair and not is_attribute:
if request_url is not None:
cookie.normalize(request_url)
cookies.append(cookie)
cookie = Cookie(key, value)
# If it's a reserved keyword add that as an attribute to the
# current cookie being scanned.
elif cookie and is_attribute:
cookie.__set_attr(key, value)
# If we've found a non-empty single token that's not a
# reserved keyword it's an error. An empty token can occur
# when there are two adjacent semi-colons (i.e. "; ;").
# We don't consider empty tokens an error.
elif key:
raise ValueError("unknown cookie token '%s'" % key)
# Flush out final cookie
if cookie:
if request_url is not None:
cookie.normalize(request_url)
cookies.append(cookie)
return cookies
@classmethod
def get_named_cookie_from_string(cls, cookie_string, cookie_name,
request_url=None, timestamp=None):
'''
A cookie string may contain multiple cookies, parse the cookie
string and return the last cookie in the string matching the
cookie name or None if not found.
This is basically a utility wrapper around the parse() class
method which iterates over what parse() returns looking for
the specific cookie.
When cookie_name appears more than once the last instance is
returned rather than the first because the ordering sequence
makes the last instance the current value.
'''
target_cookie = None
cookies = cls.parse(cookie_string)
for cookie in cookies:
if cookie.key == cookie_name:
target_cookie = cookie
if timestamp is not None:
target_cookie.timestamp = timestamp
if request_url is not None:
target_cookie.normalize(request_url)
return target_cookie
def __init__(self, key, value, domain=None, path=None, max_age=None, expires=None,
secure=None, httponly=None, timestamp=None):
self.key = key
self.value = value
self.domain = domain
self.path = path
self.max_age = max_age
self.expires = expires
self.secure = secure
self.httponly = httponly
self.timestamp = timestamp
@property
def timestamp(self):
'''
The UTC moment at which cookie was received for purposes of
computing the expiration given a Max-Age offset. The
expiration will be timestamp + max_age. The timestamp value
will aways be a datetime object.
By default the timestamp will be the moment the Cookie object
is created as this often corresponds to the moment the cookie
is received (the intent of the Max-Age attribute). But becuase
it's sometimes desirable to force a specific moment for
purposes of computing the expiration from the Max-Age the
Cookie timestamp can be updated.
Setting a value of None causes the timestamp to be set to the
current UTC time (now). You may also assign with a numeric
UNIX timestamp (seconds since the epoch UTC) or a formatted time
sting, in all cases the value will be converted to a datetime
object.
'''
return self._timestamp
@timestamp.setter
def timestamp(self, value):
if value is None:
self._timestamp = None
elif isinstance(value, datetime.datetime):
self._timestamp = value
elif isinstance(value, (six.integer_types, float)):
self._timestamp = datetime.datetime.utcfromtimestamp(value)
elif isinstance(value, six.string_types):
self._timestamp = Cookie.parse_datetime(value)
else:
raise TypeError('value must be datetime, int, long, float, basestring or None, not %s' % \
value.__class__.__name__)
@property
def expires(self):
'''
The expiration timestamp (in UTC) as a datetime object for the
cookie, or None if not set.
You may assign a value of None, a datetime object, a numeric
UNIX timestamp (seconds since the epoch UTC) or formatted time
string (the latter two will be converted to a datetime object.
'''
return self._expires
@expires.setter
def expires(self, value):
if value is None:
self._expires = None
elif isinstance(value, datetime.datetime):
self._expires = value
elif isinstance(value, (six.integer_types, float)):
self._expires = datetime.datetime.utcfromtimestamp(value)
elif isinstance(value, six.string_types):
self._expires = Cookie.parse_datetime(value)
else:
raise TypeError('value must be datetime, int, long, float, basestring or None, not %s' % \
value.__class__.__name__)
@property
def max_age(self):
'''
The lifetime duration of the cookie. Computed as an offset
from the cookie's timestamp.
'''
return self._max_age
@max_age.setter
def max_age(self, value):
if value is None:
self._max_age = None
else:
try:
self._max_age = int(value)
except Exception:
raise ValueError("Max-Age value '%s' not convertable to integer" % value)
def __set_attr(self, name, value):
'''
Sets one of the predefined cookie attributes.
'''
attr_name = Cookie.attrs.get(name.lower(), None)
if attr_name is None:
raise ValueError("unknown cookie attribute '%s'" % name)
setattr(self, attr_name, value)
def __str__(self):
components = []
components.append("%s=%s" % (self.key, self.value))
if self.domain is not None:
components.append("Domain=%s" % self.domain)
if self.path is not None:
components.append("Path=%s" % self.path)
if self.max_age is not None:
components.append("Max-Age=%s" % self.max_age)
if self.expires is not None:
components.append("Expires=%s" % Cookie.datetime_to_string(self.expires))
if self.secure:
components.append("Secure")
if self.httponly:
components.append("HttpOnly")
return '; '.join(components)
def get_expiration(self):
'''
Return the effective expiration of the cookie as a datetime
object or None if no expiration is defined. Expiration may be
defined either by the "Expires" timestamp attribute or the
"Max-Age" duration attribute. If both are set "Max-Age" takes
precedence. If neither is set the cookie has no expiration and
None will be returned.
"Max-Age" specifies the number of seconds in the future from when the
cookie is received until it expires. Effectively it means
adding "Max-Age" seconds to a timestamp to arrive at an
expiration. By default the timestamp used to mark the arrival
of the cookie is set to the moment the cookie object is
created. However sometimes it is desirable to adjust the
received timestamp to something other than the moment of
object creation, therefore you can explicitly set the arrival
timestamp used in the "Max-Age" calculation.
"Expires" specifies an explicit timestamp.
If "Max-Age" is set a datetime object is returned which is the
sum of the arrival timestamp and "Max-Age".
If "Expires" is set a datetime object is returned matching the
timestamp specified as the "Expires" value.
If neither is set None is returned.
'''
if self.max_age is not None:
return self.timestamp + datetime.timedelta(seconds=self.max_age)
if self.expires is not None:
return self.expires
return None
def normalize_expiration(self):
'''
An expiration may be specified either with an explicit
timestamp in the "Expires" attribute or via an offset
specified witht the "Max-Age" attribute. The "Max-Age"
attribute has precedence over "Expires" if both are
specified.
This method normalizes the expiration of the cookie such that
only a "Expires" attribute remains after consideration of the
"Max-Age" attribute. This is useful when storing the cookie
for future reference.
'''
self.expires = self.get_expiration()
self.max_age = None
return self.expires
def set_defaults_from_url(self, url):
'''
If cookie domain and path attributes are not specified then
they assume defaults from the request url the cookie was
received from.
'''
_scheme, domain, path, _params, _query, _fragment = urlparse(url)
if self.domain is None:
self.domain = domain.lower()
if self.path is None:
self.path = self.normalize_url_path(path)
def normalize(self, url):
'''
Missing cookie attributes will receive default values derived
from the request URL. The expiration value is normalized.
'''
self.set_defaults_from_url(url)
self.normalize_expiration()
def http_cookie(self):
'''
Return a string with just the key and value (no attributes).
This is appropriate for including in a HTTP Cookie header.
'''
return '%s=%s;' % (self.key, self.value)
def http_return_ok(self, url):
'''
Tests to see if a cookie should be returned when a request is
sent to a specific URL.
* The request url's host must match the cookie's doman
otherwise raises Cookie.URLMismatch.
* The path in the request url must contain the cookie's path
otherwise raises Cookie.URLMismatch.
* If the cookie defines an expiration date then the current
time must be less or equal to the cookie's expiration
timestamp. Will raise Cookie.Expired if a defined expiration
is not valid.
If the test fails Cookie.Expired or Cookie.URLMismatch will be raised,
otherwise True is returned.
'''
def domain_valid(url_domain, cookie_domain):
'''
Compute domain component and perform test per
RFC 6265, Section 5.1.3. "Domain Matching"
'''
# FIXME: At the moment we can't import from ipalib at the
# module level because of a dependency loop (cycle) in the
# import. Our module layout needs to be refactored.
# pylint: disable=ipa-forbidden-import
from ipalib.util import validate_domain_name
# pylint: enable=ipa-forbidden-import
try:
validate_domain_name(url_domain)
except Exception:
return False
if cookie_domain is None:
return True
url_domain = url_domain.lower()
cookie_domain = cookie_domain.lower()
if url_domain == cookie_domain:
return True
if url_domain.endswith(cookie_domain):
if cookie_domain.startswith('.'):
return True
return False
def path_valid(url_path, cookie_path):
'''
Compute path component and perform test per
RFC 6265, Section 5.1.4. "Paths and Path-Match"
'''
if cookie_path is None:
return True
cookie_path = cookie_path.lower()
request_path = self.normalize_url_path(url_path)
if cookie_path == request_path:
return True
if cookie_path and request_path.startswith(cookie_path):
if cookie_path.endswith('/'):
return True
tail = request_path[len(cookie_path):]
if tail.startswith('/'):
return True
return False
cookie_name = self.key
(
url_scheme, url_domain, url_path,
_url_params, _url_query, _url_fragment
) = urlparse(url)
cookie_expiration = self.get_expiration()
if cookie_expiration is not None:
now = datetime.datetime.utcnow()
if cookie_expiration < now:
raise Cookie.Expired("cookie named '%s'; expired at %s'" % \
(cookie_name,
self.datetime_to_string(cookie_expiration)))
if not domain_valid(url_domain, self.domain):
raise Cookie.URLMismatch("cookie named '%s'; it's domain '%s' does not match URL domain '%s'" % \
(cookie_name, self.domain, url_domain))
if not path_valid(url_path, self.path):
raise Cookie.URLMismatch("cookie named '%s'; it's path '%s' does not contain the URL path '%s'" % \
(cookie_name, self.path, url_path))
url_scheme = url_scheme.lower()
if self.httponly:
if url_scheme not in ('http', 'https'):
raise Cookie.URLMismatch("cookie named '%s'; is restricted to HTTP but it's URL scheme is '%s'" % \
(cookie_name, url_scheme))
if self.secure:
if url_scheme not in ('https',):
raise Cookie.URLMismatch("cookie named '%s'; is restricted to secure transport but it's URL scheme is '%s'" % \
(cookie_name, url_scheme))
return True