SP class should not assume SAML NameID in assertion

The basic pySAML2 service provider class upon which SPs are built should
not require that a SAML authentication request response from an IdP
contains a SAML NameID element since it is not required by the SAML 2.0
specification. This change enables the parse_authn_request_response
method for the basic pySAML2 service provider class to successfully
parse a SAML authentication request response that does not contain a
SAML NameID element.

Author: skoranda

src/saml2/client_base.py

@@ -676,50 +676,49 @@ def parse_authn_request_response(self, xmlstr, binding, outstanding=None,
         :return: An response.AuthnResponse or None
         """
 
-        try:
-            _ = self.config.entityid
-        except KeyError:
+        if not getattr(self.config, 'entityid', None):
             raise SAMLError("Missing entity_id specification")
 
-        resp = None
-        if xmlstr:
-            kwargs = {
-                "outstanding_queries": outstanding,
-                "outstanding_certs": outstanding_certs,
-                "allow_unsolicited": self.allow_unsolicited,
-                "want_assertions_signed": self.want_assertions_signed,
-                "want_response_signed": self.want_response_signed,
-                "return_addrs": self.service_urls(binding=binding),
-                "entity_id": self.config.entityid,
-                "attribute_converters": self.config.attribute_converters,
-                "allow_unknown_attributes":
-                    self.config.allow_unknown_attributes,
-                'conv_info': conv_info
-            }
-            try:
-                resp = self._parse_response(xmlstr, AuthnResponse,
-                                            "assertion_consumer_service",
-                                            binding, **kwargs)
-            except StatusError as err:
-                logger.error("SAML status error: %s", err)
-                raise
-            except UnravelError:
-                return None
-            except Exception as err:
-                logger.error("XML parse error: %s", err)
-                raise
-
-            if resp is None:
-                return None
-            elif isinstance(resp, AuthnResponse):
-                if resp.assertion is not None and len(
-                        resp.response.encrypted_assertion) == 0:
-                    self.users.add_information_about_person(resp.session_info())
-                    logger.info("--- ADDED person info ----")
-                pass
-            else:
-                logger.error("Response type not supported: %s",
-                             saml2.class_name(resp))
+        if not xmlstr:
+            return None
+
+        kwargs = {
+            "outstanding_queries": outstanding,
+            "outstanding_certs": outstanding_certs,
+            "allow_unsolicited": self.allow_unsolicited,
+            "want_assertions_signed": self.want_assertions_signed,
+            "want_response_signed": self.want_response_signed,
+            "return_addrs": self.service_urls(binding=binding),
+            "entity_id": self.config.entityid,
+            "attribute_converters": self.config.attribute_converters,
+            "allow_unknown_attributes":
+                self.config.allow_unknown_attributes,
+            'conv_info': conv_info
+        }
+
+        try:
+            resp = self._parse_response(xmlstr, AuthnResponse,
+                                        "assertion_consumer_service",
+                                        binding, **kwargs)
+        except StatusError as err:
+            logger.error("SAML status error: %s", err)
+            raise
+        except UnravelError:
+            return None
+        except Exception as err:
+            logger.error("XML parse error: %s", err)
+            raise
+
+        if not isinstance(resp, AuthnResponse):
+            logger.error("Response type not supported: %s",
+                         saml2.class_name(resp))
+            return None
+
+        if (resp.assertion and len(resp.response.encrypted_assertion) == 0 and
+                resp.assertion.subject.name_id):
+            self.users.add_information_about_person(resp.session_info())
+            logger.info("--- ADDED person info ----")
+
         return resp
 
     # ------------------------------------------------------------------------