hnbap: Accept duplicated HNB Register Request on same conn

As per what's indicated in 3GPP TS 25.469 8.2.4 Abnormal Conditions:
"""
If the HNB-GW receives a duplicate HNB REGISTER REQUEST (i.e. for an already registered HNB identified by the
unique HNB identity), then the new HNB REGISTER REQUEST shall override the existing registration and the
handling of the new HNB REGISTER REQUEST is according to section 8.2.
"""

Related: SYS#6113
Change-Id: I0250350a14a87498a2c68cd0c726ee2f1e72419d

src/osmo-hnbgw/hnbgw_hnbap.c

@@ -431,9 +431,10 @@ static int hnbgw_rx_hnb_register_req(struct hnb_context *ctx, ANY_t *in)
 		}
 	}
 
-	ctx->hnb_registered = true;
+	LOGHNB(ctx, DHNBAP, LOGL_DEBUG, "HNB-REGISTER-REQ from %s%s\n", ctx->identity_info,
+	       ctx->hnb_registered ? " (duplicated)" : "");
 
-	LOGHNB(ctx, DHNBAP, LOGL_DEBUG, "HNB-REGISTER-REQ from %s\n", ctx->identity_info);
+	ctx->hnb_registered = true;
 
 	/* Send HNBRegisterAccept */
 	rc = hnbgw_tx_hnb_register_acc(ctx);
@@ -550,9 +551,8 @@ static int hnbgw_rx_initiating_msg(struct hnb_context *hnb, HNBAP_InitiatingMess
 		}
 	} else {
 		switch (imsg->procedureCode) {
-		case HNBAP_ProcedureCode_id_HNBRegister:	/* 8.2 */
-			LOGHNB(hnb, DHNBAP, LOGL_NOTICE,
-			       "HNBAP Procedure HNB-Register not permitted for registered HNB\n");
+		case HNBAP_ProcedureCode_id_HNBRegister:	/*  8.2.4: Abnormal Condition, Accept. */
+			rc = hnbgw_rx_hnb_register_req(hnb, &imsg->value);
 			break;
 		case HNBAP_ProcedureCode_id_HNBDe_Register:	/* 8.3 */
 			rc = hnbgw_rx_hnb_deregister(hnb, &imsg->value);