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