Coverage for ipapython/cookie: 95%

100

101

102

103

# Authors:

# John Dennis <jdennis@redhat.com>

# 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 time

import datetime

import email.utils

from urllib2 import urlparse

from calendar import timegm

from ipapython.ipa_log_manager import log_mgr

'''

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 xmlrpclib. 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, 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[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):

'''

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 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):

log_mgr.get_logger(self, True)

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, (int, long, float)):

self._timestamp = datetime.datetime.utcfromtimestamp(value)

elif isinstance(value, basestring):

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, (int, long, float)):

self._expires = datetime.datetime.utcfromtimestamp(value)

elif isinstance(value, basestring):

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.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.

from ipalib.util import validate_domain_name

try:

validate_domain_name(url_domain)

except Exception, e:

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.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

Coverage for ipapython/cookie : 95%

220 statements 209 run 11 missing 0 excluded