Merge pull request #299 from stevenhammerton/sh-cas-required-attribute

SH CAS Required Attribute

synapse/config/cas.py

@@ -27,13 +27,17 @@ class CasConfig(Config):
         if cas_config:
             self.cas_enabled = True
             self.cas_server_url = cas_config["server_url"]
+            self.cas_required_attributes = cas_config.get("required_attributes", {})
         else:
             self.cas_enabled = False
             self.cas_server_url = None
+            self.cas_required_attributes = {}
 
     def default_config(self, config_dir_path, server_name, **kwargs):
         return """
         # Enable CAS for registration and login.
         #cas_config:
         #   server_url: "https://cas-server.com"
+        #   #required_attributes:
+        #   #    name: value
         """

synapse/rest/client/v1/login.py

@@ -45,8 +45,8 @@ class LoginRestServlet(ClientV1RestServlet):
         self.idp_redirect_url = hs.config.saml2_idp_redirect_url
         self.saml2_enabled = hs.config.saml2_enabled
         self.cas_enabled = hs.config.cas_enabled
-
         self.cas_server_url = hs.config.cas_server_url
+        self.cas_required_attributes = hs.config.cas_required_attributes
         self.servername = hs.config.server_name
 
     def on_GET(self, request):
@@ -125,14 +125,20 @@ class LoginRestServlet(ClientV1RestServlet):
 
     @defer.inlineCallbacks
     def do_cas_login(self, cas_response_body):
-        root = ET.fromstring(cas_response_body)
+        user, attributes = self.parse_cas_response(cas_response_body)
-        if not root.tag.endswith("serviceResponse"):
+
-            raise LoginError(401, "Invalid CAS response", errcode=Codes.UNAUTHORIZED)
+        for required_attribute, required_value in self.cas_required_attributes.items():
-        if not root[0].tag.endswith("authenticationSuccess"):
+            # If required attribute was not in CAS Response - Forbidden
-            raise LoginError(401, "Unsuccessful CAS response", errcode=Codes.UNAUTHORIZED)
+            if required_attribute not in attributes:
-        for child in root[0]:
+                raise LoginError(401, "Unauthorized", errcode=Codes.UNAUTHORIZED)
-            if child.tag.endswith("user"):
+
-                user = child.text
+            # Also need to check value
+            if required_value is not None:
+                actual_value = attributes[required_attribute]
+                # If required attribute value does not match expected - Forbidden
+                if required_value != actual_value:
+                    raise LoginError(401, "Unauthorized", errcode=Codes.UNAUTHORIZED)
+
         user_id = UserID.create(user, self.hs.hostname).to_string()
         auth_handler = self.handlers.auth_handler
         user_exists = yield auth_handler.does_user_exist(user_id)
@@ -159,7 +165,31 @@ class LoginRestServlet(ClientV1RestServlet):
 
         defer.returnValue((200, result))
 
+    def parse_cas_response(self, cas_response_body):
+        root = ET.fromstring(cas_response_body)
+        if not root.tag.endswith("serviceResponse"):
             raise LoginError(401, "Invalid CAS response", errcode=Codes.UNAUTHORIZED)
+        if not root[0].tag.endswith("authenticationSuccess"):
+            raise LoginError(401, "Unsuccessful CAS response", errcode=Codes.UNAUTHORIZED)
+        for child in root[0]:
+            if child.tag.endswith("user"):
+                user = child.text
+            if child.tag.endswith("attributes"):
+                attributes = {}
+                for attribute in child:
+                    # ElementTree library expands the namespace in attribute tags
+                    # to the full URL of the namespace.
+                    # See (https://docs.python.org/2/library/xml.etree.elementtree.html)
+                    # We don't care about namespace here and it will always be encased in
+                    # curly braces, so we remove them.
+                    if "}" in attribute.tag:
+                        attributes[attribute.tag.split("}")[1]] = attribute.text
+                    else:
+                        attributes[attribute.tag] = attribute.text
+        if user is None or attributes is None:
+            raise LoginError(401, "Invalid CAS response", errcode=Codes.UNAUTHORIZED)
+
+        return (user, attributes)
 
 
 class LoginFallbackRestServlet(ClientV1RestServlet):