irmd: Complete bidirectional flow re-keying

Extend re-key delivery beyond the locally-initiated watermark path:

Handle peer-initiated re-key requests, allowing one request and one
response per flow at a time. The client side wins if both ends try to
re-key at the same time. Caches the peer certificate to support
cert-less authenticated/signed re-keys.

After a rekey, the initiator promotes first (timer) and starts sending
under the new key. The responder observes the new key (peer_synced)
and then the responder promotes. The responder will self-decide to use
the new keys if it exhausted the older set in the case where it never
sees the peer (unidirectional flow).

Signed-off-by: Dimitri Staessens <dimitri@ouroboros.rocks>
Signed-off-by: Sander Vrijders <sander@ouroboros.rocks>

1 files changed, 6 insertions, 1 deletions

diff --git a/src/irmd/reg/flow.h b/src/irmd/reg/flow.h
index 15fc7b8f..166bed61 100644
--- a/src/irmd/reg/flow.h
+++ b/src/irmd/reg/flow.h
@@ -55,9 +55,14 @@ struct reg_flow {
                 uint8_t epoch;         /* last epoch installed by app */
                 bool    initiator;     /* OAP initiator (role 0)      */
                 bool    in_flight;     /* a re-key is in progress     */
-                uint8_t pending_seed[SYMMKEYSZ];
+                bool    req_queued;    /* a peer REQ is in the inbox  */
+                bool    resp_queued;   /* a peer RESP is in the inbox */
+                uint8_t * pending_seed;    /* secure heap; NULL until set */
                 uint8_t pending_epoch;
+                bool    pending_initiator; /* pending seed: oap_cli side */
                 bool    has_pending;   /* new seed awaits app pull    */
+                uint8_t pulled;        /* direct: per-app pull mask   */
+                buffer_t peer_crt;     /* peer cert DER, cached at HS  */
         } rk;
 
         struct ssm_rbuff * n_rb;