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Python Compiled Bytecode | 2009-03-23 | 22KB | 556 lines

# Source Generated with Decompyle++
# File: in.pyc (Python 2.6)

'''
Resource protection for Nevow. If you wish to use twisted.cred to protect your
Nevow application, you are probably most interested in
L{SessionWrapper}.
'''
__metaclass__ = type
import random
import time
import md5
import StringIO
from zope.interface import implements
from twisted.python import log, components
from twisted.internet import defer
from twisted.cred.error import UnauthorizedLogin
from twisted.cred.credentials import UsernamePassword, Anonymous

try:
    from twisted.web import http
except ImportError:
    from twisted.protocols import http

from nevow import inevow, url, stan

def _sessionCookie():
    return md5.new('%s_%s' % (str(random.random()), str(time.time()))).hexdigest()


class GuardSession(components.Componentized):
    """A user's session with a system.

    This utility class contains no functionality, but is used to
    represent a session.
    """
    implements(inevow.ISession, inevow.IGuardSession)

    def __init__(self, guard, uid):
        '''Initialize a session with a unique ID for that session.
        '''
        components.Componentized.__init__(self)
        self.guard = guard
        self.uid = uid
        self.expireCallbacks = []
        self.checkExpiredID = None
        self.setLifetime(60)
        self.portals = { }
        self.touch()


    def getLoggedInRoot(self):
        '''Get the most-recently-logged-in avatar.
        '''
        if len(self.portals) != 1:
            raise RuntimeError('Ambiguous request for current avatar.')
        len(self.portals) != 1
        return self.portals.values()[0][0]


    def resourceForPortal(self, port):
        return self.portals.get(port)


    def setDefaultResource(self, rsrc, logout):
        '''

        Change the root-resource available to the user who has already
        authenticated anonymously.  This only works in applications that DO NOT
        use the multiple-simultaneous-portals feature.  If you do not know what
        this means, you may safely ignore it.

        '''
        if len(self.portals) != 1:
            raise RuntimeError('Ambiguous request for current avatar.')
        len(self.portals) != 1
        self.setResourceForPortal(rsrc, self.portals.keys()[0], logout)


    def setResourceForPortal(self, rsrc, port, logout):
        '''Change the root-resource available to a user authenticating against a given
        portal.

        If a user was already logged in to this session from that portal, first
        log them out.

        @param rsrc: an L{IResource} implementor.
        @param port: a cred Portal instance.
        @param logout: a 0-arg callable to be invoked upon logout.
        '''
        self.portalLogout(port)
        self.portals[port] = (rsrc, logout)
        return rsrc


    def portalLogout(self, port):
        '''
        If we have previously acccepted a login for this portal, call its
        logout method and de-associate that portal from this session, catching
        any errors from the logout method.

        Otherwise: do nothing.

        @param port: a cred Portal.
        '''
        p = self.portals.get(port)
        if p:
            log.msg('Logout of portal %r' % port)
            (r, l) = p

            try:
                l()
            except:
                log.err()

            del self.portals[port]



    def setLifetime(self, lifetime):
        """Set the approximate lifetime of this session, in seconds.

        This is highly imprecise, but it allows you to set some general
        parameters about when this session will expire.  A callback will be
        scheduled each 'lifetime' seconds, and if I have not been 'touch()'ed
        in half a lifetime, I will be immediately expired.
        """
        self.lifetime = lifetime


    def notifyOnExpire(self, callback):
        '''Call this callback when the session expires or logs out.
        '''
        self.expireCallbacks.append(callback)


    def expire(self):
        '''Expire/logout of the session.
        '''
        log.msg('expired session %s' % str(self.uid))
        del self.guard.sessions[self.uid]
        for portal in self.portals.keys():
            self.portalLogout(portal)

        for c in self.expireCallbacks:

            try:
                c()
            continue
            log.err()
            continue


        self.expireCallbacks = []
        if self.checkExpiredID:
            self.checkExpiredID.cancel()
            self.checkExpiredID = None



    def touch(self):
        self.lastModified = time.time()


    def checkExpired(self):
        reactor = reactor
        import twisted.internet
        self.checkExpiredID = None
        if time.time() - self.lastModified > self.lifetime / 2:
            if self.guard.sessions.has_key(self.uid):
                self.expire()
            else:
                log.msg('no session to expire: %s' % str(self.uid))
        else:
            log.msg('session given the will to live for %s more seconds' % self.lifetime)
            self.checkExpiredID = reactor.callLater(self.lifetime, self.checkExpired)


    def __getstate__(self):
        d = self.__dict__.copy()
        if d.has_key('checkExpiredID'):
            del d['checkExpiredID']

        return d


    def __setstate__(self, d):
        self.__dict__.update(d)
        self.touch()
        self.checkExpired()



def urlToChild(ctx, *ar, **kw):
    u = url.URL.fromContext(ctx)
    for segment in ar:
        u = u.child(stan.xml(segment))

    if inevow.IRequest(ctx).method == 'POST':
        u = u.clear()

    for k, v in kw.items():
        u = u.replace(k, v)

    return u

SESSION_KEY = '__session_key__'
LOGIN_AVATAR = '__login__'
LOGOUT_AVATAR = '__logout__'

def nomind(*args):
    pass


class Forbidden(object):
    implements(inevow.IResource)

    def locateChild(self, ctx, segments):
        return self


    def renderHTTP(self, ctx):
        request = inevow.IRequest(ctx)
        request.setResponseCode(http.FORBIDDEN)
        return '<html><head><title>Forbidden</title></head><body><h1>Forbidden</h1>Request was forbidden.</body></html>'



class SessionWrapper:
    '''
    SessionWrapper

    The following class attributes can be modified on an instance
    of the class.

    @ivar secureCookies: Whether to use secure (TLS only) cookies or not.
      True (default): make cookies secure when session is initiated
      in a secure (TLS) connection.

      False: cookies do not get the secure attribute.

    @ivar: persistentCookies: Whether to use persistent (saved to disk) cookies or not.
      True: make cookies persistent, so they are valid for the
        length of the sessionLifetime even if the browser window
        is closed.

      False (default): cookies do not get saved to disk, and thus last
        only as long as the session does.  If the browser is
        closed before the session timeout, both the session
        and the cookie go away.
    '''
    implements(inevow.IResource)
    sessionLifetime = 3600
    sessionFactory = GuardSession
    credInterface = inevow.IResource
    useCookies = True
    secureCookies = True
    persistentCookies = False

    def __init__(self, portal, cookieKey = None, mindFactory = None, credInterface = None, useCookies = None):
        self.portal = portal
        if cookieKey is None:
            cookieKey = 'woven_session_' + _sessionCookie()

        self.cookieKey = cookieKey
        self.sessions = { }
        if mindFactory is None:
            mindFactory = nomind

        self.mindFactory = mindFactory
        if credInterface is not None:
            self.credInterface = credInterface

        if useCookies is not None:
            self.useCookies = useCookies

        self.resource = self


    def renderHTTP(self, ctx):
        request = inevow.IRequest(ctx)
        d = defer.maybeDeferred(self._delegate, ctx, [])

        def _cb(.0, ctx):
            (resource, segments) = .0
            if not not segments:
                raise AssertionError
            res = inevow.IResource(resource)
            return res.renderHTTP(ctx)

        d.addCallback(_cb, ctx)
        return d


    def locateChild(self, ctx, segments):
        request = inevow.IRequest(ctx)
        path = segments[0]
        if self.useCookies:
            cookie = request.getCookie(self.cookieKey)
        else:
            cookie = ''
        if path.startswith(SESSION_KEY):
            key = path[len(SESSION_KEY):]
            if key not in self.sessions:
                return (urlToChild(ctx, *segments[1:], **{
                    '__start_session__': 1 }), ())
            self.sessions[key].setLifetime(self.sessionLifetime)
            if cookie == key:
                self.sessions[key].sessionJustStarted = True
                return (urlToChild(ctx, *segments[1:]), ())
            return self.checkLogin(ctx, self.sessions[key], segments[1:], sessionURL = segments[0])
        path.startswith(SESSION_KEY)
        return self._delegate(ctx, segments)


    def _delegate(self, ctx, segments):
        """Identify the session by looking at cookies and HTTP auth headers, use that
        session key to identify the wrapped resource, then return a deferred
        which fires a 2-tuple of (resource, segments) to the top-level
        redirection code code which will delegate IResource's renderHTTP or
        locateChild methods to it
        """
        request = inevow.IRequest(ctx)
        cookie = request.getCookie(self.cookieKey)
        userpass = (request.getUser(), request.getPassword())
        httpAuthSessionKey = 'HTTP AUTH: %s:%s' % userpass
        for sessionKey in (cookie, httpAuthSessionKey):
            if sessionKey in self.sessions:
                session = self.sessions[sessionKey]
                return self.checkLogin(ctx, session, segments)

        if userpass != ('', ''):
            sz.checkExpired()
            return self.checkLogin(ctx, sz, segments, None, UsernamePassword(*userpass))
        rd = self.createSession(ctx, segments)
        return (rd, ())


    def createSession(self, ctx, segments):
        '''
        Create a new session for this request, and redirect back to the path
        given by segments.
        '''
        request = inevow.IRequest(ctx)
        newCookie = _sessionCookie()
        if self.useCookies:
            if self.secureCookies and request.isSecure():
                secure = True
            else:
                secure = False
            if self.persistentCookies and self.sessionLifetime:
                expires = http.datetimeToString(time.time() + self.sessionLifetime)
            else:
                expires = None
            request.addCookie(self.cookieKey, newCookie, path = '/%s' % '/'.join(request.prepath), secure = secure, expires = expires, domain = self.cookieDomainForRequest(request))

        sz = self.sessions[newCookie] = self.sessionFactory(self, newCookie)
        sz.args = request.args
        sz.fields = request.fields
        sz.method = request.method
        sz.received_headers = request.received_headers
        sz.checkExpired()
        return urlToChild(ctx, SESSION_KEY + newCookie, *segments)


    def checkLogin(self, ctx, session, segments, sessionURL = None, httpAuthCredentials = None):
        '''
        Associate the given request with the given session and:

            - log the user in to our portal, if they are accessing a login URL

            - log the user out from our portal (calling their logout callback),
              if they are logged in and accessing a logout URL

            - Move the request parameters saved on the session, if there are
              any, onto the request if a session just started or a login
              just succeeded.

        @return:

            - if the user is already logged in: a 2-tuple of requestObject,
              C{segments} (i.e. the segments parameter)

            - if the user is not logged in and not logging in, call login() to
              initialize an anonymous session, and return a 2-tuple of
              (rootResource, segments-parameter) from that anonymous session.
              This counts as logging in for the purpose of future calls to
              checkLogin.

            - if the user is accessing a login URL: a 2-tuple of the logged in
              resource object root and the remainder of the segments (i.e. the
              URL minus __login__) to be passed to that resource.

        '''
        request = inevow.IRequest(ctx)
        session.touch()
        request.session = session
        root = url.URL.fromContext(request)
        if sessionURL is not None:
            root = root.child(sessionURL)

        request.rememberRootURL(str(root))
        spoof = False
        if getattr(session, 'sessionJustStarted', False):
            del session.sessionJustStarted
            spoof = True

        if getattr(session, 'justLoggedIn', False):
            del session.justLoggedIn
            spoof = True

        if spoof and hasattr(session, 'args'):
            request.args = session.args
            request.fields = session.fields
            request.content = StringIO.StringIO()
            request.content.close()
            request.method = session.method
            request.received_headers = session.received_headers
            del session.args
            del session.fields
            del session.method
            del session.received_headers

        if segments and segments[0] in (LOGIN_AVATAR, LOGOUT_AVATAR):
            authCommand = segments[0]
        else:
            authCommand = None
        if httpAuthCredentials:
            if not not authCommand:
                raise AssertionError, "HTTP auth support isn't that robust.  Come up with something to do that makes sense here."
            return self.login(request, session, httpAuthCredentials, segments).addErrback(self.authRequiredError, session)
        if authCommand == LOGIN_AVATAR:
            subSegments = segments[1:]

            def unmangleURL(.0):
                (res, segs) = .0
                session.justLoggedIn = True
                u = url.URL.fromString(request.getRootURL())
                for seg in subSegments:
                    u = u.child(seg)

                return (u, ())

            return self.login(request, session, self.getCredentials(request), subSegments).addCallback(unmangleURL).addErrback(self.incorrectLoginError, ctx, subSegments, 'Incorrect login.')
        if authCommand == LOGOUT_AVATAR:
            self.explicitLogout(session)
            return (urlToChild(ctx, *segments[1:]), ())
        r = session.resourceForPortal(self.portal)
        if r:
            return (r[0], segments)
        return self.login(request, session, Anonymous(), segments).addErrback(self.incorrectLoginError, ctx, segments, 'Anonymous access not allowed.')


    def explicitLogout(self, session):
        """Hook to be overridden if you care about user-requested logout.

        Note: there is no return value from this method; it is purely a way to
        provide customized behavior that distinguishes between session-expiry
        logout, which is what 99% of code cares about, and explicit user
        logout, which you may need to be notified of if (for example) your
        application sets other HTTP cookies which refer to server-side state,
        and you want to expire that state in a manual logout but not with an
        automated logout.  (c.f. Quotient's persistent sessions.)

        If you want the user to see a customized logout page, just generate a
        logout link that looks like

            http://your-site.example.com/__logout__/my/custom/logout/stuff

        and the user will see

            http://your-site.example.com/my/custom/logout/stuff

        as their first URL after becoming anonymous again.
        """
        session.portalLogout(self.portal)


    def getCredentials(self, request):
        username = request.args.get('username', [
            ''])[0]
        password = request.args.get('password', [
            ''])[0]
        return UsernamePassword(username, password)


    def login(self, request, session, credentials, segments):
        """

        - Calls login() on our portal.

        - creates a mind from my mindFactory, with the request and credentials

        - Associates the mind with the given session.

        - Associates the resource returned from my portal's login() with my
          portal in the given session.

        @return: a Deferred which fires a 2-tuple of the resource returned from
        my portal's login() and the passed list of segments upon successful
        login.

        """
        mind = self.mindFactory(request, credentials)
        session.mind = mind
        return self.portal.login(credentials, mind, self.credInterface).addCallback(self._cbLoginSuccess, session, segments)


    def _cbLoginSuccess(self, .1, session, segments):
        (iface, res, logout) = .1
        session.setResourceForPortal(res, self.portal, logout)
        return (res, segments)


    def incorrectLoginError(self, error, ctx, segments, loginFailure):
        """ Used as an errback upon failed login, returns a 2-tuple of a failure URL
        with the query argument 'login-failure' set to the parameter
        loginFailure, and an empty list of segments, to redirect to that URL.
        The basis for this error URL, i.e. the part before the query string, is
        taken either from the 'referer' header from the given request if one
        exists, or a computed URL that points at the same page that the user is
        currently looking at to attempt login.  Any existing query string will
        be stripped.
        """
        request = inevow.IRequest(ctx)
        error.trap(UnauthorizedLogin)
        referer = request.getHeader('referer')
        if referer is not None:
            u = url.URL.fromString(referer)
        else:
            u = urlToChild(ctx, *segments)
        u = u.clear()
        u = u.add('login-failure', loginFailure)
        return (u, ())


    def authRequiredError(self, error, session):
        session.expire()
        error.trap(UnauthorizedLogin)
        return (Forbidden(), ())


    def cookieDomainForRequest(self, request):
        '''
        Specify the domain restriction on the session cookie.

        @param request: The request object in response to which a cookie is
            being set.

        @return: C{None} or a C{str} giving the domain restriction to set on
            the cookie.
        '''
        pass