Merge pull request #16 from Ph0tonic/fix_redirect_issue

Fix missing next redirect handling

multiauthenticator/multiauthenticator.py

@@ -123,7 +123,11 @@ def check_blocked_users(self, username, authentication=None):
             self._authenticators.append(authenticator)
 
     def get_custom_html(self, base_url):
-        """Re-implementation generating one login button per configured authenticator"""
+        """Re-implementation generating one login button per configured authenticator
+
+        Note: the html generated in this method will be passed through Jinja's template
+        rendering, see the login implementation in JupyterHub's sources.
+        """
 
         html = []
         for authenticator in self._authenticators:
@@ -137,7 +141,7 @@ def get_custom_html(self, base_url):
             html.append(
                 f"""
                 <div class="service-login">
-                  <a role="button" class='btn btn-jupyter btn-lg' href='{url}'>
+                  <a role="button" class='btn btn-jupyter btn-lg' href='{url}{{% if next is defined and next|length %}}?next={{{{next}}}}{{% endif %}}'>
                     Sign in with {login_service}
                   </a>
                 </div>

multiauthenticator/tests/test_multiauthenticator.py

@@ -4,6 +4,7 @@
 """Test module for the MultiAuthenticator class"""
 import pytest
 
+from jinja2 import Template
 from jupyterhub.auth import DummyAuthenticator
 from jupyterhub.auth import PAMAuthenticator
 from oauthenticator import OAuthenticator
@@ -297,3 +298,27 @@ class MyAuthenticator(OAuthenticator):
         MultiAuthenticator()
 
     assert f"Login service cannot contain {PREFIX_SEPARATOR}" in str(excinfo.value)
+
+
+def test_next_handling():
+    MultiAuthenticator.authenticators = [
+        (
+            PAMAuthenticator,
+            "/pam",
+            {"service_name": "test-service", "allowed_users": {"test"}},
+        ),
+    ]
+
+    multi_authenticator = MultiAuthenticator()
+    html = multi_authenticator.get_custom_html("")
+
+    template = Template(html)
+
+    with_next = template.render({"next": "/next-destination"})
+    assert "href='pam/login?next=/next-destination'" in with_next
+
+    without_next = template.render()
+    assert "href='pam/login'" in without_next
+
+    with_empty_next = template.render({"next": ""})
+    assert "href='pam/login'" in with_empty_next