ds_author cookie can now expire, closes #829

Refs https://github.com/simonw/datasette-auth-github/issues/62#issuecomment-642152076

datasette/actor_auth_cookie.py

@@ -1,5 +1,7 @@
 from datasette import hookimpl
 from itsdangerous import BadSignature
+import baseconv
+import time
 
 
 @hookimpl
@@ -7,6 +9,15 @@ def actor_from_request(datasette, request):
     if "ds_actor" not in request.cookies:
         return None
     try:
-        return datasette.unsign(request.cookies["ds_actor"], "actor")
+        decoded = datasette.unsign(request.cookies["ds_actor"], "actor")
+        # If it has "e" and "a" keys process the "e" expiry
+        if not isinstance(decoded, dict) or "a" not in decoded:
+            return None
+        expires_at = decoded.get("e")
+        if expires_at:
+            timestamp = int(baseconv.base62.decode(expires_at))
+            if time.time() > timestamp:
+                return None
+        return decoded["a"]
     except BadSignature:
         return None

datasette/views/special.py

@@ -62,7 +62,9 @@ class AuthTokenView(BaseView):
         if secrets.compare_digest(token, self.ds._root_token):
             self.ds._root_token = None
             response = Response.redirect("/")
-            response.set_cookie("ds_actor", self.ds.sign({"id": "root"}, "actor"))
+            response.set_cookie(
+                "ds_actor", self.ds.sign({"a": {"id": "root"}}, "actor")
+            )
             return response
         else:
             return Response("Invalid token", status=403)

docs/authentication.rst

@@ -336,11 +336,55 @@ Authentication plugins can set signed ``ds_actor`` cookies themselves like so:
 .. code-block:: python
 
     response = Response.redirect("/")
-    response.set_cookie("ds_actor", datasette.sign({"id": "cleopaws"}, "actor"))
-    return response
+    response.set_cookie("ds_actor", datasette.sign({
+        "a": {
+            "id": "cleopaws"
+        }
+    }, "actor"))
 
 Note that you need to pass ``"actor"`` as the namespace to :ref:`datasette_sign`.
 
+The shape of data encoded in the cookie is as follows::
+
+    {
+        "a": {... actor ...}
+    }
+
+.. _authentication_ds_actor_expiry:
+
+Including an expiry time
+------------------------
+
+``ds_actor`` cookies can optionally include a signed expiry timestamp, after which the cookies will no longer be valid. Authentication plugins may chose to use this mechanism to limit the lifetime of the cookie. For example, if a plugin implements single-sign-on against another source it may decide to set short-lived cookies so that if the user is removed from the SSO system their existing Datasette cookies will stop working shortly afterwards.
+
+To include an expiry, add a ``"e"`` key to the cookie value containing a `base62-encoded integer <https://pypi.org/project/python-baseconv/>`__ representing the timestamp when the cookie should expire. For example, here's how to set a cookie that expires after 24 hours:
+
+.. code-block:: python
+
+    import time
+    import baseconv
+
+    expires_at = int(time.time()) + (24 * 60 * 60)
+
+    response = Response.redirect("/")
+    response.set_cookie("ds_actor", datasette.sign({
+        "a": {
+            "id": "cleopaws"
+        },
+        "e": baseconv.base62.encode(expires_at),
+    }, "actor"))
+
+The resulting cookie will encode data that looks something like this:
+
+.. code-block:: json
+
+    {
+        "a": {
+            "id": "cleopaws"
+        },
+        "e": "1jjSji"
+    }
+
 .. _permissions:
 
 Built-in permissions

docs/internals.rst

@@ -153,12 +153,12 @@ To set cookies on the response, use the ``response.set_cookie(...)`` method. The
         samesite="lax",
     ):
 
-You can use this with :ref:`datasette.sign() <datasette_sign>` to set signed cookies. Here's how you would set the ``ds_actor`` cookie for use with Datasette :ref:`authentication <authentication>`:
+You can use this with :ref:`datasette.sign() <datasette_sign>` to set signed cookies. Here's how you would set the :ref:`ds_actor cookie <authentication_ds_actor>` for use with Datasette :ref:`authentication <authentication>`:
 
 .. code-block:: python
 
     response = Response.redirect("/")
-    response.set_cookie("ds_actor", datasette.sign({"id": "cleopaws"}, "actor"))
+    response.set_cookie("ds_actor", datasette.sign({"a": {"id": "cleopaws"}}, "actor"))
     return response
 
 .. _internals_datasette:

setup.py

@@ -57,6 +57,7 @@ setup(
         "PyYAML~=5.3",
         "mergedeep>=1.1.1,<1.4.0",
         "itsdangerous~=1.1",
+        "python-baseconv==1.2.2",
     ],
     entry_points="""
         [console_scripts]

tests/fixtures.py

@@ -109,6 +109,9 @@ class TestClient:
     def __init__(self, asgi_app):
         self.asgi_app = asgi_app
 
+    def actor_cookie(self, actor):
+        return self.ds.sign({"a": actor}, "actor")
+
     @async_to_sync
     async def get(
         self, path, allow_redirects=True, redirect_count=0, method="GET", cookies=None

tests/test_auth.py

@@ -1,4 +1,7 @@
 from .fixtures import app_client
+import baseconv
+import pytest
+import time
 
 
 def test_auth_token(app_client):
@@ -8,7 +11,9 @@ def test_auth_token(app_client):
     response = app_client.get(path, allow_redirects=False,)
     assert 302 == response.status
     assert "/" == response.headers["Location"]
-    assert {"id": "root"} == app_client.ds.unsign(response.cookies["ds_actor"], "actor")
+    assert {"a": {"id": "root"}} == app_client.ds.unsign(
+        response.cookies["ds_actor"], "actor"
+    )
     # Check that a second with same token fails
     assert app_client.ds._root_token is None
     assert 403 == app_client.get(path, allow_redirects=False,).status
@@ -16,6 +21,18 @@ def test_auth_token(app_client):
 
 def test_actor_cookie(app_client):
     "A valid actor cookie sets request.scope['actor']"
-    cookie = app_client.ds.sign({"id": "test"}, "actor")
+    cookie = app_client.actor_cookie({"id": "test"})
     response = app_client.get("/", cookies={"ds_actor": cookie})
     assert {"id": "test"} == app_client.ds._last_request.scope["actor"]
+
+
+@pytest.mark.parametrize(
+    "offset,expected", [((24 * 60 * 60), {"id": "test"}), (-(24 * 60 * 60), None),]
+)
+def test_actor_cookie_that_expires(app_client, offset, expected):
+    expires_at = int(time.time()) + offset
+    cookie = app_client.ds.sign(
+        {"a": {"id": "test"}, "e": baseconv.base62.encode(expires_at)}, "actor"
+    )
+    response = app_client.get("/", cookies={"ds_actor": cookie})
+    assert expected == app_client.ds._last_request.scope["actor"]

tests/test_canned_write.py

@@ -55,7 +55,7 @@ def test_custom_success_message(canned_write_client):
     response = canned_write_client.post(
         "/data/delete_name",
         {"rowid": 1},
-        cookies={"ds_actor": canned_write_client.ds.sign({"id": "root"}, "actor")},
+        cookies={"ds_actor": canned_write_client.actor_cookie({"id": "root"})},
         allow_redirects=False,
         csrftoken_from=True,
     )
@@ -116,7 +116,7 @@ def test_canned_query_permissions_on_database_page(canned_write_client):
     # With auth shows four
     response = canned_write_client.get(
         "/data.json",
-        cookies={"ds_actor": canned_write_client.ds.sign({"id": "root"}, "actor")},
+        cookies={"ds_actor": canned_write_client.actor_cookie({"id": "root"})},
     )
     assert 200 == response.status
     assert [
@@ -132,6 +132,6 @@ def test_canned_query_permissions_on_database_page(canned_write_client):
 def test_canned_query_permissions(canned_write_client):
     assert 403 == canned_write_client.get("/data/delete_name").status
     assert 200 == canned_write_client.get("/data/update_name").status
-    cookies = {"ds_actor": canned_write_client.ds.sign({"id": "root"}, "actor")}
+    cookies = {"ds_actor": canned_write_client.actor_cookie({"id": "root"})}
     assert 200 == canned_write_client.get("/data/delete_name", cookies=cookies).status
     assert 200 == canned_write_client.get("/data/update_name", cookies=cookies).status

tests/test_permissions.py

@@ -21,7 +21,7 @@ def test_view_instance(allow, expected_anon, expected_auth):
                 # Should be no padlock
                 assert "<h1>Datasette 🔒</h1>" not in anon_response.text
             auth_response = client.get(
-                path, cookies={"ds_actor": client.ds.sign({"id": "root"}, "actor")},
+                path, cookies={"ds_actor": client.actor_cookie({"id": "root"})},
             )
             assert expected_auth == auth_response.status
             # Check for the padlock
@@ -48,7 +48,7 @@ def test_view_database(allow, expected_anon, expected_auth):
                 # Should be no padlock
                 assert ">fixtures 🔒</h1>" not in anon_response.text
             auth_response = client.get(
-                path, cookies={"ds_actor": client.ds.sign({"id": "root"}, "actor")},
+                path, cookies={"ds_actor": client.actor_cookie({"id": "root"})},
             )
             assert expected_auth == auth_response.status
             if (
@@ -69,7 +69,7 @@ def test_database_list_respects_view_database():
         assert '<a href="/data">data</a></h2>' in anon_response.text
         assert '<a href="/fixtures">fixtures</a>' not in anon_response.text
         auth_response = client.get(
-            "/", cookies={"ds_actor": client.ds.sign({"id": "root"}, "actor")},
+            "/", cookies={"ds_actor": client.actor_cookie({"id": "root"})},
         )
         assert '<a href="/data">data</a></h2>' in auth_response.text
         assert '<a href="/fixtures">fixtures</a> 🔒</h2>' in auth_response.text
@@ -100,7 +100,7 @@ def test_database_list_respects_view_table():
         for html_fragment in html_fragments:
             assert html_fragment not in anon_response_text
         auth_response_text = client.get(
-            "/", cookies={"ds_actor": client.ds.sign({"id": "root"}, "actor")},
+            "/", cookies={"ds_actor": client.actor_cookie({"id": "root"})},
         ).text
         for html_fragment in html_fragments:
             assert html_fragment in auth_response_text
@@ -127,7 +127,7 @@ def test_view_table(allow, expected_anon, expected_auth):
             assert ">compound_three_primary_keys 🔒</h1>" not in anon_response.text
         auth_response = client.get(
             "/fixtures/compound_three_primary_keys",
-            cookies={"ds_actor": client.ds.sign({"id": "root"}, "actor")},
+            cookies={"ds_actor": client.actor_cookie({"id": "root"})},
         )
         assert expected_auth == auth_response.status
         if allow and expected_anon == 403 and expected_auth == 200:
@@ -156,7 +156,7 @@ def test_table_list_respects_view_table():
         for html_fragment in html_fragments:
             assert html_fragment not in anon_response.text
         auth_response = client.get(
-            "/fixtures", cookies={"ds_actor": client.ds.sign({"id": "root"}, "actor")}
+            "/fixtures", cookies={"ds_actor": client.actor_cookie({"id": "root"})}
         )
         for html_fragment in html_fragments:
             assert html_fragment in auth_response.text
@@ -180,7 +180,7 @@ def test_view_query(allow, expected_anon, expected_auth):
             # Should be no padlock
             assert ">fixtures 🔒</h1>" not in anon_response.text
         auth_response = client.get(
-            "/fixtures/q", cookies={"ds_actor": client.ds.sign({"id": "root"}, "actor")}
+            "/fixtures/q", cookies={"ds_actor": client.actor_cookie({"id": "root"})}
         )
         assert expected_auth == auth_response.status
         if allow and expected_anon == 403 and expected_auth == 200:
@@ -206,7 +206,7 @@ def test_execute_sql(metadata):
         assert 403 == client.get("/fixtures/facet_cities?_where=id=3").status
 
         # But for logged in user all of these should work:
-        cookies = {"ds_actor": client.ds.sign({"id": "root"}, "actor")}
+        cookies = {"ds_actor": client.actor_cookie({"id": "root"})}
         response_text = client.get("/fixtures", cookies=cookies).text
         assert form_fragment in response_text
         assert 200 == client.get("/fixtures?sql=select+1", cookies=cookies).status
@@ -231,7 +231,7 @@ def test_query_list_respects_view_query():
         assert html_fragment not in anon_response.text
         assert '"/fixtures/q"' not in anon_response.text
         auth_response = client.get(
-            "/fixtures", cookies={"ds_actor": client.ds.sign({"id": "root"}, "actor")}
+            "/fixtures", cookies={"ds_actor": client.actor_cookie({"id": "root"})}
         )
         assert html_fragment in auth_response.text
 
@@ -290,7 +290,7 @@ def test_permissions_debug(app_client):
     app_client.ds._permission_checks.clear()
     assert 403 == app_client.get("/-/permissions").status
     # With the cookie it should work
-    cookie = app_client.ds.sign({"id": "root"}, "actor")
+    cookie = app_client.actor_cookie({"id": "root"})
     response = app_client.get("/-/permissions", cookies={"ds_actor": cookie})
     # Should show one failure and one success
     soup = Soup(response.body, "html.parser")