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""" Cross Site Request Forgery Middleware.   This module provides a middleware that implements protection against request forgeries from other sites. """ from __future__ import unicode_literals   import logging import re   from django.conf import settings from django.core.urlresolvers import get_callable from django.utils.cache import patch_vary_headers from django.utils.crypto import constant_time_compare, get_random_string from django.utils.encoding import force_text from django.utils.http import is_same_domain from django.utils.six.moves.urllib.parse import urlparse   logger = logging.getLogger('django.request')   REASON_NO_REFERER = "Referer checking failed - no Referer." REASON_BAD_REFERER = "Referer checking failed - %s does not match any trusted origins." REASON_NO_CSRF_COOKIE = "CSRF cookie not set." REASON_BAD_TOKEN = "CSRF token missing or incorrect." REASON_MALFORMED_REFERER = "Referer checking failed - Referer is malformed." REASON_INSECURE_REFERER = "Referer checking failed - Referer is insecure while host is secure."   CSRF_KEY_LENGTH = 32     def _get_failure_view():     """     Returns the view to be used for CSRF rejections     """     return get_callable(settings.CSRF_FAILURE_VIEW)     def _get_new_csrf_key():     return get_random_string(CSRF_KEY_LENGTH)     def get_token(request):     """     Returns the CSRF token required for a POST form. The token is an     alphanumeric value. A new token is created if one is not already set.       A side effect of calling this function is to make the csrf_protect     decorator and the CsrfViewMiddleware add a CSRF cookie and a 'Vary: Cookie'     header to the outgoing response.  For this reason, you may need to use this     function lazily, as is done by the csrf context processor.     """     if "CSRF_COOKIE" not in request.META:         request.META["CSRF_COOKIE"] = _get_new_csrf_key()     request.META["CSRF_COOKIE_USED"] = True     return request.META["CSRF_COOKIE"]     def rotate_token(request):     """     Changes the CSRF token in use for a request - should be done on login     for security purposes.     """     request.META.update({         "CSRF_COOKIE_USED": True,         "CSRF_COOKIE": _get_new_csrf_key(),     })     def _sanitize_token(token):     # Allow only alphanum     if len(token) > CSRF_KEY_LENGTH:         return _get_new_csrf_key()     token = re.sub('[^a-zA-Z0-9]+', '', force_text(token))     if token == "":         # In case the cookie has been truncated to nothing at some point.         return _get_new_csrf_key()     return token     class CsrfViewMiddleware(object):     """     Middleware that requires a present and correct csrfmiddlewaretoken     for POST requests that have a CSRF cookie, and sets an outgoing     CSRF cookie.       This middleware should be used in conjunction with the csrf_token template     tag.     """     # The _accept and _reject methods currently only exist for the sake of the     # requires_csrf_token decorator.     def _accept(self, request):         # Avoid checking the request twice by adding a custom attribute to         # request.  This will be relevant when both decorator and middleware         # are used.         request.csrf_processing_done = True         return None       def _reject(self, request, reason):         logger.warning('Forbidden (%s): %s', reason, request.path,             extra={                 'status_code': 403,                 'request': request,             }         )         return _get_failure_view()(request, reason=reason)       def process_view(self, request, callback, callback_args, callback_kwargs):           if getattr(request, 'csrf_processing_done', False):             return None           try:             csrf_token = _sanitize_token(                 request.COOKIES[settings.CSRF_COOKIE_NAME])             # Use same token next time             request.META['CSRF_COOKIE'] = csrf_token         except KeyError:             csrf_token = None           # Wait until request.META["CSRF_COOKIE"] has been manipulated before         # bailing out, so that get_token still works         if getattr(callback, 'csrf_exempt', False):             return None           # Assume that anything not defined as 'safe' by RFC2616 needs protection         if request.method not in ('GET', 'HEAD', 'OPTIONS', 'TRACE'):             if getattr(request, '_dont_enforce_csrf_checks', False):                 # Mechanism to turn off CSRF checks for test suite.                 # It comes after the creation of CSRF cookies, so that                 # everything else continues to work exactly the same                 # (e.g. cookies are sent, etc.), but before any                 # branches that call reject().                 return self._accept(request)               if request.is_secure():                 # Suppose user visits http://example.com/                 # An active network attacker (man-in-the-middle, MITM) sends a                 # POST form that targets https://example.com/detonate-bomb/ and                 # submits it via JavaScript.                 #                 # The attacker will need to provide a CSRF cookie and token, but                 # that's no problem for a MITM and the session-independent                 # nonce we're using. So the MITM can circumvent the CSRF                 # protection. This is true for any HTTP connection, but anyone                 # using HTTPS expects better! For this reason, for                 # https://example.com/ we need additional protection that treats                 # http://example.com/ as completely untrusted. Under HTTPS,                 # Barth et al. found that the Referer header is missing for                 # same-domain requests in only about 0.2% of cases or less, so                 # we can use strict Referer checking.                 referer = force_text(                     request.META.get('HTTP_REFERER'),                     strings_only=True,                     errors='replace'                 )                 if referer is None:                     return self._reject(request, REASON_NO_REFERER)                   referer = urlparse(referer)                   # Make sure we have a valid URL for Referer.                 if '' in (referer.scheme, referer.netloc):                     return self._reject(request, REASON_MALFORMED_REFERER)                   # Ensure that our Referer is also secure.                 if referer.scheme != 'https':                     return self._reject(request, REASON_INSECURE_REFERER)                   # If there isn't a CSRF_COOKIE_DOMAIN, assume we need an exact                 # match on host:port. If not, obey the cookie rules.                 if settings.CSRF_COOKIE_DOMAIN is None:                     # request.get_host() includes the port.                     good_referer = request.get_host()                 else:                     good_referer = settings.CSRF_COOKIE_DOMAIN                     server_port = request.get_port()                     if server_port not in ('443', '80'):                         good_referer = '%s:%s' % (good_referer, server_port)                   # Here we generate a list of all acceptable HTTP referers,                 # including the current host since that has been validated                 # upstream.                 good_hosts = list(settings.CSRF_TRUSTED_ORIGINS)                 good_hosts.append(good_referer)                   if not any(is_same_domain(referer.netloc, host) for host in good_hosts):                     reason = REASON_BAD_REFERER % referer.geturl()                     return self._reject(request, reason)               if csrf_token is None:                 # No CSRF cookie. For POST requests, we insist on a CSRF cookie,                 # and in this way we can avoid all CSRF attacks, including login                 # CSRF.                 return self._reject(request, REASON_NO_CSRF_COOKIE)               # Check non-cookie token for match.             request_csrf_token = ""             if request.method == "POST":                 try:                     request_csrf_token = request.POST.get('csrfmiddlewaretoken', '')                 except IOError:                     # Handle a broken connection before we've completed reading                     # the POST data. process_view shouldn't raise any                     # exceptions, so we'll ignore and serve the user a 403                     # (assuming they're still listening, which they probably                     # aren't because of the error).                     pass               if request_csrf_token == "":                 # Fall back to X-CSRFToken, to make things easier for AJAX,                 # and possible for PUT/DELETE.                 request_csrf_token = request.META.get(settings.CSRF_HEADER_NAME, '')               if not constant_time_compare(request_csrf_token, csrf_token):                 return self._reject(request, REASON_BAD_TOKEN)           return self._accept(request)       def process_response(self, request, response):         if getattr(response, 'csrf_processing_done', False):             return response           if not request.META.get("CSRF_COOKIE_USED", False):             return response           # Set the CSRF cookie even if it's already set, so we renew         # the expiry timer.         response.set_cookie(settings.CSRF_COOKIE_NAME,                             request.META["CSRF_COOKIE"],                             max_age=settings.CSRF_COOKIE_AGE,                             domain=settings.CSRF_COOKIE_DOMAIN,                             path=settings.CSRF_COOKIE_PATH,                             secure=settings.CSRF_COOKIE_SECURE,                             httponly=settings.CSRF_COOKIE_HTTPONLY                             )         # Content varies with the CSRF cookie, so set the Vary header.         patch_vary_headers(response, ('Cookie',))         response.csrf_processing_done = True         return response""" Cross Site Request Forgery Middleware.   This module provides a middleware that implements protection against request forgeries from other sites. """ from __future__ import unicode_literals   import logging import re   from django.conf import settings from django.core.urlresolvers import get_callable from django.utils.cache import patch_vary_headers from django.utils.crypto import constant_time_compare, get_random_string from django.utils.encoding import force_text from django.utils.http import is_same_domain from django.utils.six.moves.urllib.parse import urlparse   logger = logging.getLogger('django.request')   REASON_NO_REFERER = "Referer checking failed - no Referer." REASON_BAD_REFERER = "Referer checking failed - %s does not match any trusted origins." REASON_NO_CSRF_COOKIE = "CSRF cookie not set." REASON_BAD_TOKEN = "CSRF token missing or incorrect." REASON_MALFORMED_REFERER = "Referer checking failed - Referer is malformed." REASON_INSECURE_REFERER = "Referer checking failed - Referer is insecure while host is secure."   CSRF_KEY_LENGTH = 32     def _get_failure_view():     """     Returns the view to be used for CSRF rejections     """     return get_callable(settings.CSRF_FAILURE_VIEW)     def _get_new_csrf_key():     return get_random_string(CSRF_KEY_LENGTH)     def get_token(request):     """     Returns the CSRF token required for a POST form. The token is an     alphanumeric value. A new token is created if one is not already set.       A side effect of calling this function is to make the csrf_protect     decorator and the CsrfViewMiddleware add a CSRF cookie and a 'Vary: Cookie'     header to the outgoing response.  For this reason, you may need to use this     function lazily, as is done by the csrf context processor.     """     if "CSRF_COOKIE" not in request.META:         request.META["CSRF_COOKIE"] = _get_new_csrf_key()     request.META["CSRF_COOKIE_USED"] = True     return request.META["CSRF_COOKIE"]     def rotate_token(request):     """     Changes the CSRF token in use for a request - should be done on login     for security purposes.     """     request.META.update({         "CSRF_COOKIE_USED": True,         "CSRF_COOKIE": _get_new_csrf_key(),     })     def _sanitize_token(token):     # Allow only alphanum     if len(token) > CSRF_KEY_LENGTH:         return _get_new_csrf_key()     token = re.sub('[^a-zA-Z0-9]+', '', force_text(token))     if token == "":         # In case the cookie has been truncated to nothing at some point.         return _get_new_csrf_key()     return token     class CsrfViewMiddleware(object):     """     Middleware that requires a present and correct csrfmiddlewaretoken     for POST requests that have a CSRF cookie, and sets an outgoing     CSRF cookie.       This middleware should be used in conjunction with the csrf_token template     tag.     """     # The _accept and _reject methods currently only exist for the sake of the     # requires_csrf_token decorator.     def _accept(self, request):         # Avoid checking the request twice by adding a custom attribute to         # request.  This will be relevant when both decorator and middleware         # are used.         request.csrf_processing_done = True         return None       def _reject(self, request, reason):         logger.warning('Forbidden (%s): %s', reason, request.path,             extra={                 'status_code': 403,                 'request': request,             }         )         return _get_failure_view()(request, reason=reason)       def process_view(self, request, callback, callback_args, callback_kwargs):           if getattr(request, 'csrf_processing_done', False):             return None           try:             csrf_token = _sanitize_token(                 request.COOKIES[settings.CSRF_COOKIE_NAME])             # Use same token next time             request.META['CSRF_COOKIE'] = csrf_token         except KeyError:             csrf_token = None           # Wait until request.META["CSRF_COOKIE"] has been manipulated before         # bailing out, so that get_token still works         if getattr(callback, 'csrf_exempt', False):             return None           # Assume that anything not defined as 'safe' by RFC2616 needs protection         if request.method not in ('GET', 'HEAD', 'OPTIONS', 'TRACE'):             if getattr(request, '_dont_enforce_csrf_checks', False):                 # Mechanism to turn off CSRF checks for test suite.                 # It comes after the creation of CSRF cookies, so that                 # everything else continues to work exactly the same                 # (e.g. cookies are sent, etc.), but before any                 # branches that call reject().                 return self._accept(request)               if request.is_secure():                 # Suppose user visits http://example.com/                 # An active network attacker (man-in-the-middle, MITM) sends a                 # POST form that targets https://example.com/detonate-bomb/ and                 # submits it via JavaScript.                 #                 # The attacker will need to provide a CSRF cookie and token, but                 # that's no problem for a MITM and the session-independent                 # nonce we're using. So the MITM can circumvent the CSRF                 # protection. This is true for any HTTP connection, but anyone                 # using HTTPS expects better! For this reason, for                 # https://example.com/ we need additional protection that treats                 # http://example.com/ as completely untrusted. Under HTTPS,                 # Barth et al. found that the Referer header is missing for                 # same-domain requests in only about 0.2% of cases or less, so                 # we can use strict Referer checking.                 referer = force_text(                     request.META.get('HTTP_REFERER'),                     strings_only=True,                     errors='replace'                 )                 if referer is None:                     return self._reject(request, REASON_NO_REFERER)                   referer = urlparse(referer)                   # Make sure we have a valid URL for Referer.                 if '' in (referer.scheme, referer.netloc):                     return self._reject(request, REASON_MALFORMED_REFERER)                   # Ensure that our Referer is also secure.                 if referer.scheme != 'https':                     return self._reject(request, REASON_INSECURE_REFERER)                   # If there isn't a CSRF_COOKIE_DOMAIN, assume we need an exact                 # match on host:port. If not, obey the cookie rules.                 if settings.CSRF_COOKIE_DOMAIN is None:                     # request.get_host() includes the port.                     good_referer = request.get_host()                 else:                     good_referer = settings.CSRF_COOKIE_DOMAIN                     server_port = request.get_port()                     if server_port not in ('443', '80'):                         good_referer = '%s:%s' % (good_referer, server_port)                   # Here we generate a list of all acceptable HTTP referers,                 # including the current host since that has been validated                 # upstream.                 good_hosts = list(settings.CSRF_TRUSTED_ORIGINS)                 good_hosts.append(good_referer)                   if not any(is_same_domain(referer.netloc, host) for host in good_hosts):                     reason = REASON_BAD_REFERER % referer.geturl()                     return self._reject(request, reason)               if csrf_token is None:                 # No CSRF cookie. For POST requests, we insist on a CSRF cookie,                 # and in this way we can avoid all CSRF attacks, including login                 # CSRF.                 return self._reject(request, REASON_NO_CSRF_COOKIE)               # Check non-cookie token for match.             request_csrf_token = ""             if request.method == "POST":                 try:                     request_csrf_token = request.POST.get('csrfmiddlewaretoken', '')                 except IOError:                     # Handle a broken connection before we've completed reading                     # the POST data. process_view shouldn't raise any                     # exceptions, so we'll ignore and serve the user a 403                     # (assuming they're still listening, which they probably                     # aren't because of the error).                     pass               if request_csrf_token == "":                 # Fall back to X-CSRFToken, to make things easier for AJAX,                 # and possible for PUT/DELETE.                 request_csrf_token = request.META.get(settings.CSRF_HEADER_NAME, '')               if not constant_time_compare(request_csrf_token, csrf_token):                 return self._reject(request, REASON_BAD_TOKEN)           return self._accept(request)       def process_response(self, request, response):         if getattr(response, 'csrf_processing_done', False):             return response           if not request.META.get("CSRF_COOKIE_USED", False):             return response           # Set the CSRF cookie even if it's already set, so we renew         # the expiry timer.         response.set_cookie(settings.CSRF_COOKIE_NAME,                             request.META["CSRF_COOKIE"],                             max_age=settings.CSRF_COOKIE_AGE,                             domain=settings.CSRF_COOKIE_DOMAIN,                             path=settings.CSRF_COOKIE_PATH,                             secure=settings.CSRF_COOKIE_SECURE,                             httponly=settings.CSRF_COOKIE_HTTPONLY                             )         # Content varies with the CSRF cookie, so set the Vary header.         patch_vary_headers(response, ('Cookie',))         response.csrf_processing_done = True         return response