Initial sketch for the generic data-transfer interface.

src/include/gpxe/xfer.h

@@ -0,0 +1,78 @@
+#ifndef _GPXE_XFER_H
+#define _GPXE_XFER_H
+
+/** @file
+ *
+ * Data transfer interfaces
+ *
+ */
+
+#include <stddef.h>
+#include <gpxe/interface.h>
+#include <gpxe/iobuf.h>
+
+struct xfer_interface;
+
+/** Data transfer interface operations */
+struct xfer_interface_operations {
+	/** Deliver datagram
+	 *
+	 * @v xfer		Data-transfer interface
+	 * @v src		Source  interface
+	 * @v iobuf		Datagram I/O buffer
+	 * @ret rc		Return status code
+	 */
+	int ( * deliver ) ( struct xfer_interface *xfer,
+			    struct xfer_interface *src,
+			    struct io_buffer *iobuf );
+};
+
+/** A data transfer interface */
+struct xfer_interface {
+	/** Generic object communication interface */
+	struct interface intf;
+	/** Operations for received messages */
+	struct xfer_interface_operations *op;
+};
+
+extern struct xfer_interface null_xfer;
+extern struct xfer_interface_operations null_xfer_ops;
+
+static inline struct xfer_interface *
+xfer_dest ( struct xfer_interface *xfer ) {
+	return container_of ( xfer->intf.dest, struct xfer_interface, intf );
+}
+
+/**
+ * Plug a data-transfer interface into a new destination interface
+ *
+ * @v xfer		Data-transfer interface
+ * @v dest		New destination interface
+ */
+static inline void xfer_plug ( struct xfer_interface *xfer,
+			       struct xfer_interface *dest ) {
+	plug ( &xfer->intf, &dest->intf );
+}
+
+/**
+ * Unplug a data-transfer interface
+ *
+ * @v xfer		Data-transfer interface
+ */
+static inline void xfer_unplug ( struct xfer_interface *xfer ) {
+	plug ( &xfer->intf, &null_xfer.intf );
+}
+
+/**
+ * Terminate a data-transfer interface
+ *
+ * @v xfer		Data-transfer interface
+ *
+ * After calling this method, no further messages will be received via
+ * the interface.
+ */
+static inline void xfer_terminate ( struct xfer_interface *xfer ) {
+	xfer->op = &null_xfer_ops;
+};
+
+#endif /* _GPXE_XFER_H */