kxdpgun: block eventual creation of conns when recvd initial...

...just to make sure

src/libknot/quic/quic.c

@@ -631,6 +631,10 @@ int knot_quic_handle(knot_quic_table_t *table, knot_quic_reply_t *reply,
 		goto finish;
 	}
 
+	if (conn == NULL && (table->flags & KNOT_QUIC_TABLE_CLIENT_ONLY)) {
+		return KNOT_EOK;
+	}
+
 	if (conn != NULL && (conn->flags & KNOT_QUIC_CONN_BLOCKED)) {
 		return KNOT_EOK;
 	}

src/libknot/quic/quic_conn.h

@@ -106,8 +106,12 @@ typedef struct knot_quic_cid {
 	struct knot_quic_cid *next;
 } knot_quic_cid_t;
 
+typedef enum {
+	KNOT_QUIC_TABLE_CLIENT_ONLY = (1 << 0),
+} knot_quic_table_flag_t;
+
 typedef struct knot_quic_table {
-	uint32_t flags; // unused yet
+	knot_quic_table_flag_t flags;
 	size_t size;
 	size_t usage;
 	size_t pointers;

src/utils/kxdpgun/main.c

@@ -371,6 +371,7 @@ void *xdp_gun_thread(void *_ctx)
 			goto cleanup;
 		}
 		quic_table->qlog_dir = ctx->qlog_dir;
+		quic_table->flags |= KNOT_QUIC_TABLE_CLIENT_ONLY;
 #else
 		assert(0);
 #endif // ENABLE_QUIC