Add responder feature for initial cred exchanges

Add new APIs:
* krb5_get_init_creds_opt_set_responder
* krb5_responder_get_challenge
* krb5_responder_list_questions
* krb5_responder_set_answer

If a caller sets a responder, it will be invoked after preauth modules
have had a chance to review their incoming padata but before they produce
outgoing padata.  The responder will be presented a set of questions with
optional challenges.  The responder should then answer all questions it knows
how to handle.  Both the answers and the challenges are printable UTF-8 and
may contain encoded, structured data specific to the question asked.

Add two new callbacks and one optional method to the clpreauth
interface.  The new method (prep_questions) allows modules to ask questions
by setting them in the responder context using one of the new callbacks
(ask_responder_question).  The other new callback (get_responder_answer) is
used by the process method to read the answers to the questions asked.

ticket: 7355 (new)

1 files changed, 31 insertions, 0 deletions

diff --git a/src/lib/krb5/krb/int-proto.h b/src/lib/krb5/krb/int-proto.h
index f794f143e..6f3de8f34 100644
--- a/src/lib/krb5/krb/int-proto.h
+++ b/src/lib/krb5/krb/int-proto.h
@@ -203,4 +203,35 @@ krb5_error_code
 k5_init_creds_get(krb5_context context, krb5_init_creds_context ctx,
                   int *use_master);
 
+krb5_error_code
+k5_response_items_new(k5_response_items **ri_out);
+
+void
+k5_response_items_free(k5_response_items *ri);
+
+void
+k5_response_items_reset(k5_response_items *ri);
+
+krb5_boolean
+k5_response_items_empty(const k5_response_items *ri);
+
+const char * const *
+k5_response_items_list_questions(const k5_response_items *ri);
+
+krb5_error_code
+k5_response_items_ask_question(k5_response_items *ri, const char *question,
+                               const char *challenge);
+
+const char *
+k5_response_items_get_challenge(const k5_response_items *ri,
+                                const char *question);
+
+krb5_error_code
+k5_response_items_set_answer(k5_response_items *ri, const char *question,
+                             const char *answer);
+
+const char *
+k5_response_items_get_answer(const k5_response_items *ri,
+                             const char *question);
+
 #endif /* KRB5_INT_FUNC_PROTO__ */