Fixed #30747 -- Renamed is_safe_url() to url_has_allowed_host_and_scheme().

django/contrib/auth/views.py

@@ -17,7 +17,9 @@ from django.http import HttpResponseRedirect, QueryDict
 from django.shortcuts import resolve_url
 from django.urls import reverse_lazy
 from django.utils.decorators import method_decorator
-from django.utils.http import is_safe_url, urlsafe_base64_decode
+from django.utils.http import (
+    url_has_allowed_host_and_scheme, urlsafe_base64_decode,
+)
 from django.utils.translation import gettext_lazy as _
 from django.views.decorators.cache import never_cache
 from django.views.decorators.csrf import csrf_protect
@@ -70,7 +72,7 @@ class LoginView(SuccessURLAllowedHostsMixin, FormView):
             self.redirect_field_name,
             self.request.GET.get(self.redirect_field_name, '')
         )
-        url_is_safe = is_safe_url(
+        url_is_safe = url_has_allowed_host_and_scheme(
             url=redirect_to,
             allowed_hosts=self.get_success_url_allowed_hosts(),
             require_https=self.request.is_secure(),
@@ -138,7 +140,7 @@ class LogoutView(SuccessURLAllowedHostsMixin, TemplateView):
                 self.redirect_field_name,
                 self.request.GET.get(self.redirect_field_name)
             )
-            url_is_safe = is_safe_url(
+            url_is_safe = url_has_allowed_host_and_scheme(
                 url=next_page,
                 allowed_hosts=self.get_success_url_allowed_hosts(),
                 require_https=self.request.is_secure(),

django/utils/http.py

@@ -294,15 +294,18 @@ def is_same_domain(host, pattern):
     )
 
 
-def is_safe_url(url, allowed_hosts, require_https=False):
+def url_has_allowed_host_and_scheme(url, allowed_hosts, require_https=False):
     """
-    Return ``True`` if the url is a safe redirection (i.e. it doesn't point to
-    a different host and uses a safe scheme).
+    Return ``True`` if the url uses an allowed host and a safe scheme.
 
     Always return ``False`` on an empty url.
 
     If ``require_https`` is ``True``, only 'https' will be considered a valid
     scheme, as opposed to 'http' and 'https' with the default, ``False``.
+
+    Note: "True" doesn't entail that a URL is "safe". It may still be e.g.
+    quoted incorrectly. Ensure to also use django.utils.encoding.iri_to_uri()
+    on the path component of untrusted URLs.
     """
     if url is not None:
         url = url.strip()
@@ -314,8 +317,19 @@ def is_safe_url(url, allowed_hosts, require_https=False):
         allowed_hosts = {allowed_hosts}
     # Chrome treats \ completely as / in paths but it could be part of some
     # basic auth credentials so we need to check both URLs.
-    return (_is_safe_url(url, allowed_hosts, require_https=require_https) and
-            _is_safe_url(url.replace('\\', '/'), allowed_hosts, require_https=require_https))
+    return (
+        _url_has_allowed_host_and_scheme(url, allowed_hosts, require_https=require_https) and
+        _url_has_allowed_host_and_scheme(url.replace('\\', '/'), allowed_hosts, require_https=require_https)
+    )
+
+
+def is_safe_url(url, allowed_hosts, require_https=False):
+    warnings.warn(
+        'django.utils.http.is_safe_url() is deprecated in favor of '
+        'url_has_allowed_host_and_scheme().',
+        RemovedInDjango40Warning, stacklevel=2,
+    )
+    return url_has_allowed_host_and_scheme(url, allowed_hosts, require_https)
 
 
 # Copied from urllib.parse.urlparse() but uses fixed urlsplit() function.
@@ -367,7 +381,7 @@ def _urlsplit(url, scheme='', allow_fragments=True):
     return _coerce_result(v)
 
 
-def _is_safe_url(url, allowed_hosts, require_https=False):
+def _url_has_allowed_host_and_scheme(url, allowed_hosts, require_https=False):
     # Chrome considers any URL with more than two slashes to be absolute, but
     # urlparse is not so flexible. Treat any url with three slashes as unsafe.
     if url.startswith('///'):

django/views/i18n.py

@@ -10,7 +10,7 @@ from django.http import HttpResponse, HttpResponseRedirect, JsonResponse
 from django.template import Context, Engine
 from django.urls import translate_url
 from django.utils.formats import get_format
-from django.utils.http import is_safe_url
+from django.utils.http import url_has_allowed_host_and_scheme
 from django.utils.translation import (
     LANGUAGE_SESSION_KEY, check_for_language, get_language,
 )
@@ -32,11 +32,17 @@ def set_language(request):
     any state.
     """
     next = request.POST.get('next', request.GET.get('next'))
-    if ((next or not request.is_ajax()) and
-            not is_safe_url(url=next, allowed_hosts={request.get_host()}, require_https=request.is_secure())):
+    if (
+        (next or not request.is_ajax()) and
+        not url_has_allowed_host_and_scheme(
+            url=next, allowed_hosts={request.get_host()}, require_https=request.is_secure(),
+        )
+    ):
         next = request.META.get('HTTP_REFERER')
         next = next and unquote(next)  # HTTP_REFERER may be encoded.
-        if not is_safe_url(url=next, allowed_hosts={request.get_host()}, require_https=request.is_secure()):
+        if not url_has_allowed_host_and_scheme(
+            url=next, allowed_hosts={request.get_host()}, require_https=request.is_secure(),
+        ):
             next = '/'
     response = HttpResponseRedirect(next) if next else HttpResponse(status=204)
     if request.method == 'POST':

docs/internals/deprecation.txt

@@ -32,6 +32,8 @@ details on these changes.
 
 * ``django.utils.text.unescape_entities()`` will be removed.
 
+* ``django.utils.http.is_safe_url()`` will be removed.
+
 .. _deprecation-removed-in-3.1:
 
 3.1

docs/releases/3.0.txt

@@ -601,6 +601,14 @@ Miscellaneous
   :func:`html.unescape`. Note that unlike ``unescape_entities()``,
   ``html.unescape()`` evaluates lazy strings immediately.
 
+* To avoid possible confusion as to effective scope, the private internal
+  utility ``is_safe_url()`` is renamed to
+  ``url_has_allowed_host_and_scheme()``. That a URL has an allowed host and
+  scheme doesn't in general imply that it's "safe". It may still be quoted
+  incorrectly, for example. Ensure to also use
+  :func:`~django.utils.encoding.iri_to_uri` on the path component of untrusted
+  URLs.
+
 .. _removed-features-3.0:
 
 Features removed in 3.0

tests/utils_tests/test_http.py

@@ -7,8 +7,8 @@ from django.utils.deprecation import RemovedInDjango40Warning
 from django.utils.http import (
     base36_to_int, escape_leading_slashes, http_date, int_to_base36,
     is_safe_url, is_same_domain, parse_etags, parse_http_date, quote_etag,
-    urlencode, urlquote, urlquote_plus, urlsafe_base64_decode,
-    urlsafe_base64_encode, urlunquote, urlunquote_plus,
+    url_has_allowed_host_and_scheme, urlencode, urlquote, urlquote_plus,
+    urlsafe_base64_decode, urlsafe_base64_encode, urlunquote, urlunquote_plus,
 )
 
 
@@ -128,7 +128,7 @@ class Base36IntTests(SimpleTestCase):
             self.assertEqual(base36_to_int(b36), n)
 
 
-class IsSafeURLTests(unittest.TestCase):
+class IsSafeURLTests(SimpleTestCase):
     def test_bad_urls(self):
         bad_urls = (
             'http://example.com',
@@ -164,7 +164,10 @@ class IsSafeURLTests(unittest.TestCase):
         )
         for bad_url in bad_urls:
             with self.subTest(url=bad_url):
-                self.assertIs(is_safe_url(bad_url, allowed_hosts={'testserver', 'testserver2'}), False)
+                self.assertIs(
+                    url_has_allowed_host_and_scheme(bad_url, allowed_hosts={'testserver', 'testserver2'}),
+                    False,
+                )
 
     def test_good_urls(self):
         good_urls = (
@@ -181,21 +184,27 @@ class IsSafeURLTests(unittest.TestCase):
         )
         for good_url in good_urls:
             with self.subTest(url=good_url):
-                self.assertIs(is_safe_url(good_url, allowed_hosts={'otherserver', 'testserver'}), True)
+                self.assertIs(
+                    url_has_allowed_host_and_scheme(good_url, allowed_hosts={'otherserver', 'testserver'}),
+                    True,
+                )
 
     def test_basic_auth(self):
         # Valid basic auth credentials are allowed.
-        self.assertIs(is_safe_url(r'http://user:pass@testserver/', allowed_hosts={'user:pass@testserver'}), True)
+        self.assertIs(
+            url_has_allowed_host_and_scheme(r'http://user:pass@testserver/', allowed_hosts={'user:pass@testserver'}),
+            True,
+        )
 
     def test_no_allowed_hosts(self):
         # A path without host is allowed.
-        self.assertIs(is_safe_url('/confirm/me@example.com', allowed_hosts=None), True)
+        self.assertIs(url_has_allowed_host_and_scheme('/confirm/me@example.com', allowed_hosts=None), True)
         # Basic auth without host is not allowed.
-        self.assertIs(is_safe_url(r'http://testserver\@example.com', allowed_hosts=None), False)
+        self.assertIs(url_has_allowed_host_and_scheme(r'http://testserver\@example.com', allowed_hosts=None), False)
 
     def test_allowed_hosts_str(self):
-        self.assertIs(is_safe_url('http://good.com/good', allowed_hosts='good.com'), True)
-        self.assertIs(is_safe_url('http://good.co/evil', allowed_hosts='good.com'), False)
+        self.assertIs(url_has_allowed_host_and_scheme('http://good.com/good', allowed_hosts='good.com'), True)
+        self.assertIs(url_has_allowed_host_and_scheme('http://good.co/evil', allowed_hosts='good.com'), False)
 
     def test_secure_param_https_urls(self):
         secure_urls = (
@@ -205,7 +214,10 @@ class IsSafeURLTests(unittest.TestCase):
         )
         for url in secure_urls:
             with self.subTest(url=url):
-                self.assertIs(is_safe_url(url, allowed_hosts={'example.com'}, require_https=True), True)
+                self.assertIs(
+                    url_has_allowed_host_and_scheme(url, allowed_hosts={'example.com'}, require_https=True),
+                    True,
+                )
 
     def test_secure_param_non_https_urls(self):
         insecure_urls = (
@@ -215,7 +227,18 @@ class IsSafeURLTests(unittest.TestCase):
         )
         for url in insecure_urls:
             with self.subTest(url=url):
-                self.assertIs(is_safe_url(url, allowed_hosts={'example.com'}, require_https=True), False)
+                self.assertIs(
+                    url_has_allowed_host_and_scheme(url, allowed_hosts={'example.com'}, require_https=True),
+                    False,
+                )
+
+    def test_is_safe_url_deprecated(self):
+        msg = (
+            'django.utils.http.is_safe_url() is deprecated in favor of '
+            'url_has_allowed_host_and_scheme().'
+        )
+        with self.assertWarnsMessage(RemovedInDjango40Warning, msg):
+            is_safe_url('https://example.com', allowed_hosts={'example.com'})
 
 
 class URLSafeBase64Tests(unittest.TestCase):