SSO: redirect to public URL before setting cookies (#9436)

... otherwise, we don't get the cookie back.

3 files changed, 60 insertions, 26 deletions

diff --git a/tests/rest/client/v1/test_login.py b/tests/rest/client/v1/test_login.py
index fb29eaed6f..744d8d0941 100644
--- a/tests/rest/client/v1/test_login.py
+++ b/tests/rest/client/v1/test_login.py
@@ -15,7 +15,7 @@
 
 import time
 import urllib.parse
-from typing import Any, Dict, List, Union
+from typing import Any, Dict, List, Optional, Union
 from urllib.parse import urlencode
 
 from mock import Mock
@@ -47,8 +47,14 @@ except ImportError:
     HAS_JWT = False
 
 
-# public_base_url used in some tests
-BASE_URL = "https://synapse/"
+# synapse server name: used to populate public_baseurl in some tests
+SYNAPSE_SERVER_PUBLIC_HOSTNAME = "synapse"
+
+# public_baseurl for some tests. It uses an http:// scheme because
+# FakeChannel.isSecure() returns False, so synapse will see the requested uri as
+# http://..., so using http in the public_baseurl stops Synapse trying to redirect to
+# https://....
+BASE_URL = "http://%s/" % (SYNAPSE_SERVER_PUBLIC_HOSTNAME,)
 
 # CAS server used in some tests
 CAS_SERVER = "https://fake.test"
@@ -480,11 +486,7 @@ class MultiSSOTestCase(unittest.HomeserverTestCase):
     def test_multi_sso_redirect(self):
         """/login/sso/redirect should redirect to an identity picker"""
         # first hit the redirect url, which should redirect to our idp picker
-        channel = self.make_request(
-            "GET",
-            "/_matrix/client/r0/login/sso/redirect?redirectUrl="
-            + urllib.parse.quote_plus(TEST_CLIENT_REDIRECT_URL),
-        )
+        channel = self._make_sso_redirect_request(False, None)
         self.assertEqual(channel.code, 302, channel.result)
         uri = channel.headers.getRawHeaders("Location")[0]
 
@@ -628,34 +630,21 @@ class MultiSSOTestCase(unittest.HomeserverTestCase):
 
     def test_client_idp_redirect_msc2858_disabled(self):
         """If the client tries to pick an IdP but MSC2858 is disabled, return a 400"""
-        channel = self.make_request(
-            "GET",
-            "/_matrix/client/unstable/org.matrix.msc2858/login/sso/redirect/oidc?redirectUrl="
-            + urllib.parse.quote_plus(TEST_CLIENT_REDIRECT_URL),
-        )
+        channel = self._make_sso_redirect_request(True, "oidc")
         self.assertEqual(channel.code, 400, channel.result)
         self.assertEqual(channel.json_body["errcode"], "M_UNRECOGNIZED")
 
     @override_config({"experimental_features": {"msc2858_enabled": True}})
     def test_client_idp_redirect_to_unknown(self):
         """If the client tries to pick an unknown IdP, return a 404"""
-        channel = self.make_request(
-            "GET",
-            "/_matrix/client/unstable/org.matrix.msc2858/login/sso/redirect/xxx?redirectUrl="
-            + urllib.parse.quote_plus(TEST_CLIENT_REDIRECT_URL),
-        )
+        channel = self._make_sso_redirect_request(True, "xxx")
         self.assertEqual(channel.code, 404, channel.result)
         self.assertEqual(channel.json_body["errcode"], "M_NOT_FOUND")
 
     @override_config({"experimental_features": {"msc2858_enabled": True}})
     def test_client_idp_redirect_to_oidc(self):
         """If the client pick a known IdP, redirect to it"""
-        channel = self.make_request(
-            "GET",
-            "/_matrix/client/unstable/org.matrix.msc2858/login/sso/redirect/oidc?redirectUrl="
-            + urllib.parse.quote_plus(TEST_CLIENT_REDIRECT_URL),
-        )
-
+        channel = self._make_sso_redirect_request(True, "oidc")
         self.assertEqual(channel.code, 302, channel.result)
         oidc_uri = channel.headers.getRawHeaders("Location")[0]
         oidc_uri_path, oidc_uri_query = oidc_uri.split("?", 1)
@@ -663,6 +652,30 @@ class MultiSSOTestCase(unittest.HomeserverTestCase):
         # it should redirect us to the auth page of the OIDC server
         self.assertEqual(oidc_uri_path, TEST_OIDC_AUTH_ENDPOINT)
 
+    def _make_sso_redirect_request(
+        self, unstable_endpoint: bool = False, idp_prov: Optional[str] = None
+    ):
+        """Send a request to /_matrix/client/r0/login/sso/redirect
+
+        ... or the unstable equivalent
+
+        ... possibly specifying an IDP provider
+        """
+        endpoint = (
+            "/_matrix/client/unstable/org.matrix.msc2858/login/sso/redirect"
+            if unstable_endpoint
+            else "/_matrix/client/r0/login/sso/redirect"
+        )
+        if idp_prov is not None:
+            endpoint += "/" + idp_prov
+        endpoint += "?redirectUrl=" + urllib.parse.quote_plus(TEST_CLIENT_REDIRECT_URL)
+
+        return self.make_request(
+            "GET",
+            endpoint,
+            custom_headers=[("Host", SYNAPSE_SERVER_PUBLIC_HOSTNAME)],
+        )
+
     @staticmethod
     def _get_value_from_macaroon(macaroon: pymacaroons.Macaroon, key: str) -> str:
         prefix = key + " = "
diff --git a/tests/rest/client/v1/utils.py b/tests/rest/client/v1/utils.py
index 8231a423f3..946740aa5d 100644
--- a/tests/rest/client/v1/utils.py
+++ b/tests/rest/client/v1/utils.py
@@ -542,13 +542,30 @@ class RestHelper:
         if client_redirect_url:
             params["redirectUrl"] = client_redirect_url
 
-        # hit the redirect url (which will issue a cookie and state)
+        # hit the redirect url (which should redirect back to the redirect url. This
+        # is the easiest way of figuring out what the Host header ought to be set to
+        # to keep Synapse happy.
         channel = make_request(
             self.hs.get_reactor(),
             self.site,
             "GET",
             "/_matrix/client/r0/login/sso/redirect?" + urllib.parse.urlencode(params),
         )
+        assert channel.code == 302
+
+        # hit the redirect url again with the right Host header, which should now issue
+        # a cookie and redirect to the SSO provider.
+        location = channel.headers.getRawHeaders("Location")[0]
+        parts = urllib.parse.urlsplit(location)
+        channel = make_request(
+            self.hs.get_reactor(),
+            self.site,
+            "GET",
+            urllib.parse.urlunsplit(("", "") + parts[2:]),
+            custom_headers=[
+                ("Host", parts[1]),
+            ],
+        )
 
         assert channel.code == 302
         channel.extract_cookies(cookies)
diff --git a/tests/rest/client/v2_alpha/test_auth.py b/tests/rest/client/v2_alpha/test_auth.py
index c26ad824f7..9734a2159a 100644
--- a/tests/rest/client/v2_alpha/test_auth.py
+++ b/tests/rest/client/v2_alpha/test_auth.py
@@ -161,7 +161,11 @@ class UIAuthTests(unittest.HomeserverTestCase):
 
     def default_config(self):
         config = super().default_config()
-        config["public_baseurl"] = "https://synapse.test"
+
+        # public_baseurl uses an http:// scheme because FakeChannel.isSecure() returns
+        # False, so synapse will see the requested uri as http://..., so using http in
+        # the public_baseurl stops Synapse trying to redirect to https.
+        config["public_baseurl"] = "http://synapse.test"
 
         if HAS_OIDC:
             # we enable OIDC as a way of testing SSO flows