cas_provider/views.py

   1 from __future__ import unicode_literals
   2
   3 import logging
   4 logger = logging.getLogger('cas_provider.views')
   5
   6 try:
   7     from urllib.error import HTTPError, URLError
   8     from urllib.parse import parse_qsl, urlencode, urlparse, urlsplit, urlunsplit
   9     from urllib.request import urlopen
  10 except ImportError:
  11     from urllib import urlencode
  12     from urllib2 import HTTPError, URLError, urlopen
  13     from urlparse import parse_qsl, urlparse, urlsplit, urlunsplit
  14 from functools import wraps
  15
  16 from django.utils.decorators import available_attrs
  17 from django.views.decorators.debug import sensitive_post_parameters
  18 from django.views.decorators.cache import cache_control
  19 from django.utils.cache import patch_cache_control
  20 from django.views.decorators.csrf import csrf_protect
  21
  22 from django.http import HttpResponse, HttpResponseRedirect
  23 from django.conf import settings
  24 from django.contrib.auth import login as auth_login, logout as auth_logout
  25 from django.core.urlresolvers import get_callable
  26 from django.shortcuts import render
  27 from django.utils.translation import ugettext as _
  28 from django.template import RequestContext
  29 from django.contrib.auth import authenticate
  30 from django.core.urlresolvers import reverse
  31 from django.utils.translation import ugettext as _
  32
  33 from lxml import etree
  34 from cas_provider.attribute_formatters import NSMAP, CAS
  35 from cas_provider.models import ProxyGrantingTicket, ProxyTicket
  36 from cas_provider.models import ServiceTicket
  37
  38 from cas_provider.forms import LoginForm, MergeLoginForm
  39
  40 from . import signals
  41
  42 __all__ = ['login', 'validate', 'logout', 'service_validate']
  43
  44 INVALID_TICKET = 'INVALID_TICKET'
  45 INVALID_SERVICE = 'INVALID_SERVICE'
  46 INVALID_REQUEST = 'INVALID_REQUEST'
  47 INTERNAL_ERROR = 'INTERNAL_ERROR'
  48
  49 ERROR_MESSAGES = (
  50     (INVALID_TICKET, 'The provided ticket is invalid.'),
  51     (INVALID_SERVICE, 'Service is invalid'),
  52     (INVALID_REQUEST, 'Not all required parameters were sent.'),
  53     (INTERNAL_ERROR, 'An internal error occurred during ticket validation'),
  54     )
  55
  56
  57 logger = logging.getLogger(__name__)
  58
  59
  60 _never_cache = cache_control(no_cache=True, must_revalidate=True)
  61
  62
  63 def never_cache(view_func):
  64     """
  65     Decorator that adds headers to a response so that it will
  66     never be cached.
  67     """
  68     @wraps(view_func, assigned=available_attrs(view_func))
  69     def _wrapped_view_func(request, *args, **kwargs):
  70         response = view_func(request, *args, **kwargs)
  71         patch_cache_control(response, no_cache=True,
  72                             must_revalidate=True, proxy_revalidate=True)
  73         response['Pragma'] = 'no-cache'
  74         return response
  75     return _wrapped_view_func
  76
  77
  78 @sensitive_post_parameters()
  79 @csrf_protect
  80 @never_cache
  81 def login(request, template_name='cas/login.html',
  82           success_redirect=settings.LOGIN_REDIRECT_URL,
  83           warn_template_name='cas/warn.html', **kwargs):
  84     merge = kwargs.get('merge', False)
  85     logging.debug('CAS Provider Login view. Method is %s, merge is %s, template is %s.',
  86                   request.method, merge, template_name)
  87
  88     service = request.GET.get('service', None)
  89     if service is not None:
  90         # Save the service on the session, for later use if we end up
  91         # in one of the more complicated workflows.
  92         request.session['service'] = service
  93
  94     user = request.user
  95
  96     errors = []
  97
  98     if request.method == 'POST':
  99         if merge:
 100             form = MergeLoginForm(request.POST, request=request)
 101         else:
 102             form = LoginForm(request.POST, request=request)
 103
 104         if form.is_valid():
 105             service = form.cleaned_data.get('service', None)
 106             try:
 107                 auth_args = dict(username=form.cleaned_data['username'],
 108                                  password=form.cleaned_data['password'])
 109                 if merge:
 110                     # We only want to send the merge argument if it's
 111                     # True. If it it's False, we want it to propagate
 112                     # through the auth backends properly.
 113                     auth_args['merge'] = merge
 114                 user = authenticate(**auth_args)
 115             except:
 116                 # Need to merge the accounts?
 117                 if merge:
 118                     # We shouldn't get here...
 119                     raise
 120                 else:
 121                     base_url = reverse('cas_provider_merge')
 122                     args = dict(
 123                         success_redirect=success_redirect,
 124                         username=form.cleaned_data['username'],
 125                         )
 126                     if service is not None:
 127                         args['service'] = service
 128                     args = urlencode(args)
 129
 130                     url = '%s?%s' % (base_url, args)
 131                     logging.debug('Redirecting to %s', url)
 132                     return HttpResponseRedirect(url)
 133
 134             if user is None:
 135                 errors.append(_('Incorrect username and/or password.'))
 136             else:
 137                 if user.is_active:
 138                     auth_login(request, user)
 139
 140     else:  # Not a POST...
 141         if merge:
 142             form = MergeLoginForm(initial={'service': service, 'username': request.GET.get('username')})
 143         else:
 144             form = LoginForm(initial={'service': service})
 145
 146     if user is not None and user.is_authenticated():
 147         # We have an authenticated user.
 148         if not user.is_active:
 149             errors.append(_('This account is disabled. Please contact us if you feel it should be enabled again.'))
 150         else:
 151             # Send the on_cas_login signal. If we get an HttpResponse, return that.
 152             for receiver, response in signals.on_cas_login.send(sender=login, request=request, **kwargs):
 153                 if isinstance(response, HttpResponse):
 154                     return response
 155
 156             if service is None:
 157                 # Try and pull the service off the session
 158                 service = request.session.pop('service', service)
 159
 160             signals.on_cas_login_success.send(sender=login, request=request,
 161                                               service=service, **kwargs)
 162
 163             if service is None:
 164                 # Normal internal success redirection.
 165                 logging.debug('Redirecting to %s', success_redirect)
 166                 return HttpResponseRedirect(success_redirect)
 167             else:
 168                 if request.GET.get('warn', False):
 169                     return render(request, warn_template_name, {
 170                         'service': service,
 171                         'warn': False
 172                     })
 173
 174                 # Create a service ticket and redirect to the service.
 175                 ticket = ServiceTicket.objects.create(service=service, user=user)
 176                 if 'service' in request.session:
 177                     # Don't need this any more.
 178                     del request.session['service']
 179
 180                 url = ticket.get_redirect_url()
 181                 logging.debug('Redirecting to %s', url)
 182                 return HttpResponseRedirect(url)
 183
 184     logging.debug('Rendering response on %s, merge is %s', template_name, merge)
 185     return render(request, template_name, {'form': form, 'errors': errors})
 186
 187
 188 @never_cache
 189 def validate(request):
 190     """Validate ticket via CAS v.1 protocol
 191     """
 192     service = request.GET.get('service', None)
 193     ticket_string = request.GET.get('ticket', None)
 194     logger.info('Validating ticket %s for %s', ticket_string, service)
 195     if service is not None and ticket_string is not None:
 196         #renew = request.GET.get('renew', True)
 197         #if not renew:
 198         # TODO: check user SSO session
 199         try:
 200             ticket = ServiceTicket.objects.get(ticket=ticket_string)
 201             assert ticket.service == service
 202         except ServiceTicket.DoesNotExist:
 203             logger.exception("Tried to validate with an invalid ticket %s for %s", ticket_string, service)
 204         except Exception as e:
 205             logger.exception('Got an exception: %s', e)
 206         else:
 207             username = ticket.user.username
 208             ticket.delete()
 209
 210             results = signals.on_cas_collect_histories.send(sender=validate, for_user=ticket.user)
 211             histories = '\n'.join('\n'.join(rs) for rc, rs in results)
 212             logger.info('Validated %s %s', username, "(also %s)" % histories if histories else '')
 213             return HttpResponse("yes\n%s\n%s" % (username, histories))
 214
 215     logger.info('Validation failed.')
 216     return HttpResponse("no\n\n")
 217
 218
 219 @never_cache
 220 def logout(request, template_name='cas/logout.html',
 221            auto_redirect=settings.CAS_AUTO_REDIRECT_AFTER_LOGOUT):
 222     url = request.GET.get('url', None)
 223     if request.user.is_authenticated():
 224         for ticket in ServiceTicket.objects.filter(user=request.user):
 225             ticket.delete()
 226         auth_logout(request)
 227         if url and auto_redirect:
 228             return HttpResponseRedirect(url)
 229     return render(request, template_name, {'url': url})
 230
 231
 232 @never_cache
 233 def proxy(request):
 234     targetService = request.GET['targetService']
 235     pgt_id = request.GET['pgt']
 236
 237     try:
 238         proxyGrantingTicket = ProxyGrantingTicket.objects.get(ticket=pgt_id)
 239     except ProxyGrantingTicket.DoesNotExist:
 240         return _cas2_error_response(INVALID_TICKET)
 241
 242     pt = ProxyTicket.objects.create(proxyGrantingTicket=proxyGrantingTicket,
 243         user=proxyGrantingTicket.user,
 244         service=targetService)
 245     return _cas2_proxy_success(pt.ticket)
 246
 247
 248 def ticket_validate(service, ticket_string, pgtUrl):
 249     if service is None or ticket_string is None:
 250         return _cas2_error_response(INVALID_REQUEST)
 251
 252     try:
 253         if ticket_string.startswith('ST'):
 254             ticket = ServiceTicket.objects.get(ticket=ticket_string)
 255         elif ticket_string.startswith('PT'):
 256             ticket = ProxyTicket.objects.get(ticket=ticket_string)
 257         else:
 258             return _cas2_error_response(INVALID_TICKET,
 259                 '%(ticket)s is neither Service (ST-...) nor Proxy Ticket (PT-...)' % {
 260                     'ticket': ticket_string})
 261     except ServiceTicket.DoesNotExist:
 262         return _cas2_error_response(INVALID_TICKET)
 263
 264     ticketUrl = urlparse(ticket.service)
 265     serviceUrl = urlparse(service)
 266
 267     if not(ticketUrl.hostname == serviceUrl.hostname and ticketUrl.path == serviceUrl.path and ticketUrl.port == serviceUrl.port):
 268         return _cas2_error_response(INVALID_SERVICE)
 269
 270     pgtIouId = None
 271     proxies = ()
 272     if pgtUrl is not None:
 273         pgt = generate_proxy_granting_ticket(pgtUrl, ticket)
 274         if pgt:
 275             pgtIouId = pgt.pgtiou
 276
 277     try:
 278         proxyTicket = ticket.proxyticket
 279     except ProxyTicket.DoesNotExist:
 280         pass
 281     else:
 282         pgt = proxyTicket.proxyGrantingTicket
 283         # I am issued by this proxy granting ticket
 284         while pgt.pgt is not None:
 285             proxies += (pgt.service,)
 286             pgt = pgt.pgt
 287
 288     user = ticket.user
 289     ticket.delete()
 290     return _cas2_sucess_response(user, pgtIouId, proxies)
 291
 292
 293 @never_cache
 294 def service_validate(request):
 295     """Validate ticket via CAS v.2 protocol"""
 296     service = request.GET.get('service', None)
 297     ticket_string = request.GET.get('ticket', None)
 298     pgtUrl = request.GET.get('pgtUrl', None)
 299     if ticket_string.startswith('PT-'):
 300         return _cas2_error_response(INVALID_TICKET, "serviceValidate cannot verify proxy tickets")
 301     else:
 302         return ticket_validate(service, ticket_string, pgtUrl)
 303
 304
 305 @never_cache
 306 def proxy_validate(request):
 307     """Validate ticket via CAS v.2 protocol"""
 308     service = request.GET.get('service', None)
 309     ticket_string = request.GET.get('ticket', None)
 310     pgtUrl = request.GET.get('pgtUrl', None)
 311     return ticket_validate(service, ticket_string, pgtUrl)
 312
 313
 314 def generate_proxy_granting_ticket(pgt_url, ticket):
 315     proxy_callback_good_status = (200, 202, 301, 302, 304)
 316     uri = list(urlsplit(pgt_url))
 317
 318     pgt = ProxyGrantingTicket()
 319     pgt.user = ticket.user
 320     pgt.service = ticket.service
 321     # Remember if it's a chained PGT.
 322     pgt.pgt = getattr(ticket, 'proxyGrantingTicket', None)
 323
 324     params = {'pgtId': pgt.ticket, 'pgtIou': pgt.pgtiou}
 325
 326     query = dict(parse_qsl(uri[4]))
 327     query.update(params)
 328
 329     uri[3] = urlencode(query)
 330
 331     try:
 332         urlopen(urlunsplit(uri))
 333     except HTTPError as e:
 334         if not e.code in proxy_callback_good_status:
 335             logger.debug('Checking Proxy Callback URL {0} returned {1}. Not issuing PGT.'.format(uri, e.code))
 336             return
 337     except URLError as e:
 338         logger.debug('Checking Proxy Callback URL {0} raised URLError. Not issuing PGT.'.format(uri))
 339         return
 340
 341     pgt.save()
 342     return pgt
 343
 344
 345 def _cas2_proxy_success(pt):
 346     return HttpResponse(proxy_success(pt))
 347
 348
 349 def _cas2_sucess_response(user, pgt=None, proxies=None):
 350     return HttpResponse(auth_success_response(user, pgt, proxies), content_type='text/xml')
 351
 352
 353 def _cas2_error_response(code, message=None):
 354     return HttpResponse('''<cas:serviceResponse xmlns:cas="http://www.yale.edu/tp/cas">
 355             <cas:authenticationFailure code="%(code)s">
 356                 %(message)s
 357             </cas:authenticationFailure>
 358         </cas:serviceResponse>''' % {
 359         'code': code,
 360         'message': message if message else dict(ERROR_MESSAGES).get(code)
 361     }, content_type='text/xml')
 362
 363
 364 def proxy_success(pt):
 365     response = etree.Element(CAS + 'serviceResponse', nsmap=NSMAP)
 366     proxySuccess = etree.SubElement(response, CAS + 'proxySuccess')
 367     proxyTicket = etree.SubElement(proxySuccess, CAS + 'proxyTicket')
 368     proxyTicket.text = pt
 369     return etree.tostring(response, encoding='unicode')
 370
 371
 372 def auth_success_response(user, pgt, proxies):
 373     response = etree.Element(CAS + 'serviceResponse', nsmap=NSMAP)
 374     auth_success = etree.SubElement(response, CAS + 'authenticationSuccess')
 375     username = etree.SubElement(auth_success, CAS + 'user')
 376     username.text = user.username
 377
 378     attrs = {}
 379     for receiver, custom in signals.cas_collect_custom_attributes.send(sender=auth_success_response, user=user):
 380         if custom:
 381             attrs.update(custom)
 382
 383     identifiers = [i for sr, rr in signals.on_cas_collect_histories.send(sender=validate, for_user=user)
 384                    for i in rr]
 385
 386     if identifiers:
 387         # Singular `identifier`, as that is the name of the element tag(s).
 388         attrs['identifier'] = identifiers
 389
 390     if attrs:
 391         formatter = get_callable(settings.CAS_CUSTOM_ATTRIBUTES_FORMATER)
 392         formatter(auth_success, attrs)
 393
 394     if pgt:
 395         pgtElement = etree.SubElement(auth_success, CAS + 'proxyGrantingTicket')
 396         pgtElement.text = pgt
 397
 398     if proxies:
 399         proxiesElement = etree.SubElement(auth_success, CAS + "proxies")
 400         for proxy in proxies:
 401             proxyElement = etree.SubElement(proxiesElement, CAS + "proxy")
 402             proxyElement.text = proxy
 403
 404     return etree.tostring(response, encoding='unicode')