Add support for SingleSignOnService negotiating which binding to use

src/saml2/client.py

@@ -42,7 +42,7 @@ class Saml2Client(Base):
     """ The basic pySAML2 service provider class """
 
     def prepare_for_authenticate(self, entityid=None, relay_state="",
-                                 binding=None, vorg="",
+                                 binding=saml2.BINDING_HTTP_REDIRECT, vorg="",
                                  nameid_format=None,
                                  scoping=None, consent=None, extensions=None,
                                  sign=None,
@@ -64,6 +64,47 @@ class Saml2Client(Base):
         :return: session id and AuthnRequest info
         """
 
+        reqid, negotiated_binding, info = self.prepare_for_negotiated_authenticate(
+            entityid=entityid,
+            relay_state=relay_state,
+            binding=binding,
+            vorg=vorg,
+            nameid_format=nameid_format,
+            scoping=scoping,
+            consent=consent,
+            extensions=extensions,
+            sign=sign,
+            response_binding=response_binding,
+            **kwargs)
+
+        assert negotiated_binding == binding
+
+        return reqid, info
+
+    def prepare_for_negotiated_authenticate(self, entityid=None, relay_state="",
+                                            binding=None, vorg="",
+                                            nameid_format=None,
+                                            scoping=None, consent=None, extensions=None,
+                                            sign=None,
+                                            response_binding=saml2.BINDING_HTTP_POST,
+                                            **kwargs):
+        """ Makes all necessary preparations for an authentication request that negotiates
+        which binding to use for authentication.
+
+        :param entityid: The entity ID of the IdP to send the request to
+        :param relay_state: To where the user should be returned after
+            successfull log in.
+        :param binding: Which binding to use for sending the request
+        :param vorg: The entity_id of the virtual organization I'm a member of
+        :param scoping: For which IdPs this query are aimed.
+        :param consent: Whether the principal have given her consent
+        :param extensions: Possible extensions
+        :param sign: Whether the request should be signed or not.
+        :param response_binding: Which binding to use for receiving the response
+        :param kwargs: Extra key word arguments
+        :return: session id and AuthnRequest info
+        """
+
         expected_binding = binding
 
         for binding in [BINDING_HTTP_REDIRECT, BINDING_HTTP_POST]:
@@ -88,7 +129,7 @@ class Saml2Client(Base):
 
             return reqid, binding, http_info
         else:
-            raise SignonError("No binding available for singon")
+            raise SignOnError("No supported bindings available for authentication")
 
     def global_logout(self, name_id, reason="", expire=None, sign=None):
         """ More or less a layer of indirection :-/

src/saml2/client_base.py

@@ -71,7 +71,7 @@ class VerifyError(SAMLError):
     pass
 
 
-class SignonError(SAMLError):
+class SignOnError(SAMLError):
     pass
 
 

tests/test_51_client.py

@@ -619,7 +619,26 @@ class TestClientWithDummy():
     def test_do_authn(self):
         binding = BINDING_HTTP_REDIRECT
         response_binding = BINDING_HTTP_POST
-        sid, auth_binding, http_args = self.client.prepare_for_authenticate(
+        sid, http_args = self.client.prepare_for_authenticate(
+            IDP, "http://www.example.com/relay_state",
+            binding=binding, response_binding=response_binding)
+
+        assert isinstance(sid, basestring)
+        assert len(http_args) == 4
+        assert http_args["headers"][0][0] == "Location"
+        assert http_args["data"] == []
+        redirect_url = http_args["headers"][0][1]
+        _, _, _, _, qs, _ = urlparse.urlparse(redirect_url)
+        qs_dict = urlparse.parse_qs(qs)
+        req = self.server.parse_authn_request(qs_dict["SAMLRequest"][0],
+                                              binding)
+        resp_args = self.server.response_args(req.message, [response_binding])
+        assert resp_args["binding"] == response_binding
+
+    def test_do_negotiated_authn(self):
+        binding = BINDING_HTTP_REDIRECT
+        response_binding = BINDING_HTTP_POST
+        sid, auth_binding, http_args = self.client.prepare_for_negotiated_authenticate(
             IDP, "http://www.example.com/relay_state",
             binding=binding, response_binding=response_binding)
 
@@ -670,7 +689,40 @@ class TestClientWithDummy():
     def test_post_sso(self):
         binding = BINDING_HTTP_POST
         response_binding = BINDING_HTTP_POST
-        sid, auth_binding, http_args = self.client.prepare_for_authenticate(
+        sid, http_args = self.client.prepare_for_authenticate(
+            "urn:mace:example.com:saml:roland:idp", relay_state="really",
+            binding=binding, response_binding=response_binding)
+        _dic = unpack_form(http_args["data"][3])
+
+        req = self.server.parse_authn_request(_dic["SAMLRequest"], binding)
+        resp_args = self.server.response_args(req.message, [response_binding])
+        assert resp_args["binding"] == response_binding
+
+        # Normally a response would now be sent back to the users web client
+        # Here I fake what the client will do
+        # create the form post
+
+        http_args["data"] = urllib.urlencode(_dic)
+        http_args["method"] = "POST"
+        http_args["dummy"] = _dic["SAMLRequest"]
+        http_args["headers"] = [('Content-type',
+                                 'application/x-www-form-urlencoded')]
+
+        response = self.client.send(**http_args)
+        print response.text
+        _dic = unpack_form(response.text[3], "SAMLResponse")
+        resp = self.client.parse_authn_request_response(_dic["SAMLResponse"],
+                                                        BINDING_HTTP_POST,
+                                                        {sid: "/"})
+        ac = resp.assertion.authn_statement[0].authn_context
+        assert ac.authenticating_authority[0].text == \
+            'http://www.example.com/login'
+        assert ac.authn_context_class_ref.text == INTERNETPROTOCOLPASSWORD
+
+    def test_negotiated_post_sso(self):
+        binding = BINDING_HTTP_POST
+        response_binding = BINDING_HTTP_POST
+        sid, auth_binding, http_args = self.client.prepare_for_negotiated_authenticate(
             "urn:mace:example.com:saml:roland:idp", relay_state="really",
             binding=binding, response_binding=response_binding)
         _dic = unpack_form(http_args["data"][3])