cas_provider/views.py

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