from django.conf import settings
from django.http import HttpResponseForbidden
from django.template import Context, Engine, TemplateDoesNotExist, loader
from django.utils.translation import gettext as _
from django.utils.version import get_docs_version
# We include the template inline since we need to be able to reliably display
# this error message, especially for the sake of developers, and there isn't any
# other way of making it available independent of what is in the settings file.
# Only the text appearing with DEBUG=False is translated. Normal translation
# tags cannot be used with this inline templates as makemessages would not be
# able to discover the strings.
CSRF_FAILURE_TEMPLATE = """
<!DOCTYPE html>
<html lang="en">
<head>
<meta http-equiv="content-type" content="text/html; charset=utf-8">
<meta name="robots" content="NONE,NOARCHIVE">
<title>403 Forbidden</title>
<style type="text/css">
html * { padding:0; margin:0; }
body * { padding:10px 20px; }
body * * { padding:0; }
body { font:small sans-serif; background:#eee; color:#000; }
body>div { border-bottom:1px solid #ddd; }
h1 { font-weight:normal; margin-bottom:.4em; }
h1 span { font-size:60%; color:#666; font-weight:normal; }
#info { background:#f6f6f6; }
#info ul { margin: 0.5em 4em; }
#info p, #summary p { padding-top:10px; }
#summary { background: #ffc; }
#explanation { background:#eee; border-bottom: 0px none; }
</style>
</head>
<body>
<div id="summary">
<h1>{{ title }} <span>(403)</span></h1>
<p>{{ main }}</p>
{% if no_referer %}
<p>{{ no_referer1 }}</p>
<p>{{ no_referer2 }}</p>
<p>{{ no_referer3 }}</p>
{% endif %}
{% if no_cookie %}
<p>{{ no_cookie1 }}</p>
<p>{{ no_cookie2 }}</p>
{% endif %}
</div>
{% if DEBUG %}
<div id="info">
<h2>Help</h2>
{% if reason %}
<p>Reason given for failure:</p>
<pre>
{{ reason }}
</pre>
{% endif %}
<p>In general, this can occur when there is a genuine Cross Site Request Forgery, or when
<a
href="https://docs.djangoproject.com/en/{{ docs_version }}/ref/csrf/">Django's
CSRF mechanism</a> has not been used correctly. For POST forms, you need to
ensure:</p>
<ul>
<li>Your browser is accepting cookies.</li>
<li>The view function passes a <code>request</code> to the template's <a
href="https://docs.djangoproject.com/en/dev/topics/templates/#django.template.backends.base.Template.render"><code>render</code></a>
method.</li>
<li>In the template, there is a <code>{% templatetag openblock %} csrf_token
{% templatetag closeblock %}</code> template tag inside each POST form that
targets an internal URL.</li>
<li>If you are not using <code>CsrfViewMiddleware</code>, then you must use
<code>csrf_protect</code> on any views that use the <code>csrf_token</code>
template tag, as well as those that accept the POST data.</li>
<li>The form has a valid CSRF token. After logging in in another browser
tab or hitting the back button after a login, you may need to reload the
page with the form, because the token is rotated after a login.</li>
</ul>
<p>You're seeing the help section of this page because you have <code>DEBUG =
True</code> in your Django settings file. Change that to <code>False</code>,
and only the initial error message will be displayed. </p>
<p>You can customize this page using the CSRF_FAILURE_VIEW setting.</p>
</div>
{% else %}
<div id="explanation">
<p><small>{{ more }}</small></p>
</div>
{% endif %}
</body>
</html>
"""
CSRF_FAILURE_TEMPLATE_NAME = "403_csrf.html"
def csrf_failure(request, reason="", template_name=CSRF_FAILURE_TEMPLATE_NAME):
"""
Default view used when request fails CSRF protection
"""
from django.middleware.csrf import REASON_NO_REFERER, REASON_NO_CSRF_COOKIE
c = {
'title': _("Forbidden"),
'main': _("CSRF verification failed. Request aborted."),
'reason': reason,
'no_referer': reason == REASON_NO_REFERER,
'no_referer1': _(
'You are seeing this message because this HTTPS site requires a '
'“Referer header” to be sent by your Web browser, but none was '
'sent. This header is required for security reasons, to ensure '
'that your browser is not being hijacked by third parties.'),
'no_referer2': _(
'If you have configured your browser to disable “Referer” headers, '
'please re-enable them, at least for this site, or for HTTPS '
'connections, or for “same-origin” requests.'),
'no_referer3': _(
'If you are using the <meta name="referrer" '
'content=\"no-referrer\"> tag or including the “Referrer-Policy: '
'no-referrer” header, please remove them. The CSRF protection '
'requires the “Referer” header to do strict referer checking. If '
'you’re concerned about privacy, use alternatives like '
'<a rel=\"noreferrer\" …> for links to third-party sites.'),
'no_cookie': reason == REASON_NO_CSRF_COOKIE,
'no_cookie1': _(
"You are seeing this message because this site requires a CSRF "
"cookie when submitting forms. This cookie is required for "
"security reasons, to ensure that your browser is not being "
"hijacked by third parties."),
'no_cookie2': _(
'If you have configured your browser to disable cookies, please '
're-enable them, at least for this site, or for “same-origin” '
'requests.'),
'DEBUG': settings.DEBUG,
'docs_version': get_docs_version(),
'more': _("More information is available with DEBUG=True."),
}
try:
t = loader.get_template(template_name)
except TemplateDoesNotExist:
if template_name == CSRF_FAILURE_TEMPLATE_NAME:
# If the default template doesn't exist, use the string template.
t = Engine().from_string(CSRF_FAILURE_TEMPLATE)
c = Context(c)
else:
# Raise if a developer-specified template doesn't exist.
raise
return HttpResponseForbidden(t.render(c), content_type='text/html')