make idp_id available to the pre_session_create_pipeline - fixes #45

README.md

@@ -294,6 +294,7 @@ with the IdP but before a session is created.
 
 This is just a vanilla Plug Pipeline. The SAML assertion from
 the IdP is made available in the Plug connection as a "private".
+(The pipeline plugs have access to the `idp_id` in this assertion.)
 If you want to derive new attributes, create an Elixir map data (`%{}`)
 and update the `computed` field of the SAML assertion and put it back
 in the Plug connection private with `Conn.put_private` call.
@@ -311,6 +312,9 @@ defmodule MySamlyPipeline do
   def compute_attributes(conn, _opts) do
     assertion = conn.private[:samly_assertion]
 
+    # This assertion has the idp_id
+    # %Assertion{idp_id: idp_id} = assertion
+
     first_name = Map.get(assertion.attributes, "first_name")
     last_name  = Map.get(assertion.attributes, "last_name")
 

lib/samly/sp_handler.ex

@@ -36,6 +36,7 @@ defmodule Samly.SPHandler do
 
     with {:ok, assertion} <- Helper.decode_idp_auth_resp(sp, saml_encoding, saml_response),
          :ok <- validate_authresp(conn, assertion, relay_state),
+         assertion = %Assertion{assertion | idp_id: idp_id},
          conn = conn |> put_private(:samly_assertion, assertion),
          {:halted, %Conn{halted: false} = conn} <- {:halted, pipethrough(conn, pipeline)} do
       updated_assertion = conn.private[:samly_assertion]