Introduce name resolution interface and named socket opener.

src/include/gpxe/resolv.h

@@ -7,41 +7,153 @@
  *
  */
 
-struct sockaddr;
-
-#include <gpxe/async.h>
+#include <gpxe/refcnt.h>
+#include <gpxe/interface.h>
 #include <gpxe/tables.h>
 
+struct sockaddr;
+struct resolv_interface;
+
+/** Name resolution interface operations */
+struct resolv_interface_operations {
+	/** Name resolution completed
+	 *
+	 * @v resolv		Name resolution interface
+	 * @v sa		Completed socket address (if successful)
+	 * @v rc		Final status code
+	 */
+	void ( * done ) ( struct resolv_interface *resolv,
+			  struct sockaddr *sa, int rc );
+};
+
+/** A name resolution interface */
+struct resolv_interface {
+	/** Generic object communication interface */
+	struct interface intf;
+	/** Operations for received messages */
+	struct resolv_interface_operations *op;
+};
+
+extern struct resolv_interface null_resolv;
+extern struct resolv_interface_operations null_resolv_ops;
+
+/**
+ * Initialise a name resolution interface
+ *
+ * @v resolv		Name resolution interface
+ * @v op		Name resolution interface operations
+ * @v refcnt		Containing object reference counter, or NULL
+ */
+static inline void resolv_init ( struct resolv_interface *resolv,
+				 struct resolv_interface_operations *op,
+				 struct refcnt *refcnt ) {
+	resolv->intf.dest = &null_resolv.intf;
+	resolv->intf.refcnt = refcnt;
+	resolv->op = op;
+}
+
+/**
+ * Get name resolution interface from generic object communication interface
+ *
+ * @v intf		Generic object communication interface
+ * @ret resolv		Name resolution interface
+ */
+static inline __attribute__ (( always_inline )) struct resolv_interface *
+intf_to_resolv ( struct interface *intf ) {
+	return container_of ( intf, struct resolv_interface, intf );
+}
+
+/**
+ * Get reference to destination name resolution interface
+ *
+ * @v resolv		Name resolution interface
+ * @ret dest		Destination interface
+ */
+static inline __attribute__ (( always_inline )) struct resolv_interface *
+resolv_get_dest ( struct resolv_interface *resolv ) {
+	return intf_to_resolv ( intf_get ( resolv->intf.dest ) );
+}
+
+/**
+ * Drop reference to name resolution interface
+ *
+ * @v resolv		name resolution interface
+ */
+static inline __attribute__ (( always_inline )) void
+resolv_put ( struct resolv_interface *resolv ) {
+	intf_put ( &resolv->intf );
+}
+
+/**
+ * Plug a name resolution interface into a new destination interface
+ *
+ * @v resolv		Name resolution interface
+ * @v dest		New destination interface
+ */
+static inline __attribute__ (( always_inline )) void
+resolv_plug ( struct resolv_interface *resolv, struct resolv_interface *dest ) {
+	plug ( &resolv->intf, &dest->intf );
+}
+
+/**
+ * Plug two name resolution interfaces together
+ *
+ * @v a			Name resolution interface A
+ * @v b			Name resolution interface B
+ */
+static inline __attribute__ (( always_inline )) void
+resolv_plug_plug ( struct resolv_interface *a, struct resolv_interface *b ) {
+	plug_plug ( &a->intf, &b->intf );
+}
+
+/**
+ * Unplug a name resolution interface
+ *
+ * @v resolv		Name resolution interface
+ */
+static inline __attribute__ (( always_inline )) void
+resolv_unplug ( struct resolv_interface *resolv ) {
+	plug ( &resolv->intf, &null_resolv.intf );
+}
+
+/**
+ * Stop using a name resolution interface
+ *
+ * @v resolv		Name resolution interface
+ *
+ * After calling this method, no further messages will be received via
+ * the interface.
+ */
+static inline void resolv_nullify ( struct resolv_interface *resolv ) {
+	resolv->op = &null_resolv_ops;
+};
+
 /** A name resolver */
 struct resolver {
 	/** Name of this resolver (e.g. "DNS") */
 	const char *name;
 	/** Start name resolution
 	 *
-	 * @v name		Host name to resolve
-	 * @v sa		Socket address to fill in
-	 * @v parent		Parent asynchronous operation
+	 * @v resolv		Name resolution interface
+	 * @v name		Name to resolve
+	 * @v sa		Socket address to complete
 	 * @ret rc		Return status code
-	 *
-	 * The asynchronous process must be prepared to accept
-	 * SIGKILL.
 	 */
-	int ( * resolv ) ( const char *name, struct sockaddr *sa,
-			   struct async *parent );
+	int ( * resolv ) ( struct resolv_interface *resolv, const char *name,
+			   struct sockaddr *sa );
 };
 
-/** A name resolution in progress */
-struct resolution {
-	/** Asynchronous operation */
-	struct async async;
-	/** Numner of active child resolvers */
-	unsigned int pending;
-};
+/** Numeric resolver priority */
+#define RESOLV_NUMERIC 01
+
+/** Normal resolver priority */
+#define RESOLV_NORMAL 02
 
 /** Register as a name resolver */
-#define __resolver __table ( struct resolver, resolvers, 01 )
+#define __resolver( resolv_order ) \
+	__table ( struct resolver, resolvers, resolv_order )
 
-extern int resolv ( const char *name, struct sockaddr *sa,
-		    struct async *parent );
+extern int resolv ( struct resolv_interface *resolv, const char *name,
+		    struct sockaddr *sa );
 
 #endif /* _GPXE_RESOLV_H */