io: introduce a network socket listener API

The existing QIOChannelSocket class provides the ability to
listen on a single socket at a time. This patch introduces
a QIONetListener class that provides a higher level API
concept around listening for network services, allowing
for listening on multiple sockets.

Reviewed-by: Eric Blake <[email protected]>
Signed-off-by: Daniel P. Berrange <[email protected]>

include/io/net-listener.h

@@ -0,0 +1,174 @@
+/*
+ * QEMU network listener
+ *
+ * Copyright (c) 2016-2017 Red Hat, Inc.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#ifndef QIO_NET_LISTENER_H
+#define QIO_NET_LISTENER_H
+
+#include "io/channel-socket.h"
+
+#define TYPE_QIO_NET_LISTENER "qio-net-listener"
+#define QIO_NET_LISTENER(obj)                                    \
+    OBJECT_CHECK(QIONetListener, (obj), TYPE_QIO_NET_LISTENER)
+#define QIO_NET_LISTENER_CLASS(klass)                                    \
+    OBJECT_CLASS_CHECK(QIONetListenerClass, klass, TYPE_QIO_NET_LISTENER)
+#define QIO_NET_LISTENER_GET_CLASS(obj)                                  \
+    OBJECT_GET_CLASS(QIONetListenerClass, obj, TYPE_QIO_NET_LISTENER)
+
+typedef struct QIONetListener QIONetListener;
+typedef struct QIONetListenerClass QIONetListenerClass;
+
+typedef void (*QIONetListenerClientFunc)(QIONetListener *listener,
+                                         QIOChannelSocket *sioc,
+                                         gpointer data);
+
+/**
+ * QIONetListener:
+ *
+ * The QIONetListener object encapsulates the management of a
+ * listening socket. It is able to listen on multiple sockets
+ * concurrently, to deal with the scenario where IPv4 / IPv6
+ * needs separate sockets, or there is a need to listen on a
+ * subset of interface IP addresses, instead of the wildcard
+ * address.
+ */
+struct QIONetListener {
+    Object parent;
+
+    char *name;
+    QIOChannelSocket **sioc;
+    gulong *io_tag;
+    size_t nsioc;
+
+    bool connected;
+
+    QIONetListenerClientFunc io_func;
+    gpointer io_data;
+    GDestroyNotify io_notify;
+};
+
+struct QIONetListenerClass {
+    ObjectClass parent;
+};
+
+
+/**
+ * qio_net_listener_new:
+ *
+ * Create a new network listener service, which is not
+ * listening on any sockets initially.
+ *
+ * Returns: the new listener
+ */
+QIONetListener *qio_net_listener_new(void);
+
+
+/**
+ * qio_net_listener_set_name:
+ * @listener: the network listener object
+ * @name: the listener name
+ *
+ * Set the name of the listener. This is used as a debugging
+ * aid, to set names on any GSource instances associated
+ * with the listener
+ */
+void qio_net_listener_set_name(QIONetListener *listener,
+                               const char *name);
+
+/**
+ * qio_net_listener_open_sync:
+ * @listener: the network listener object
+ * @addr: the address to listen on
+ * @errp: pointer to a NULL initialized error object
+ *
+ * Synchronously open a listening connection on all
+ * addresses associated with @addr. This method may
+ * also be invoked multiple times, in order to have a
+ * single listener on multiple distinct addresses.
+ */
+int qio_net_listener_open_sync(QIONetListener *listener,
+                               SocketAddress *addr,
+                               Error **errp);
+
+/**
+ * qio_net_listener_add:
+ * @listener: the network listener object
+ * @sioc: the socket I/O channel
+ *
+ * Associate a listening socket I/O channel with the
+ * listener. The listener will acquire a new reference
+ * on @sioc, so the caller should release its own reference
+ * if it no longer requires the object.
+ */
+void qio_net_listener_add(QIONetListener *listener,
+                          QIOChannelSocket *sioc);
+
+/**
+ * qio_net_listener_set_client_func:
+ * @listener: the network listener object
+ * @func: the callback function
+ * @data: opaque data to pass to @func
+ * @notify: callback to free @data
+ *
+ * Register @func to be invoked whenever a new client
+ * connects to the listener. @func will be invoked
+ * passing in the QIOChannelSocket instance for the
+ * client.
+ */
+void qio_net_listener_set_client_func(QIONetListener *listener,
+                                      QIONetListenerClientFunc func,
+                                      gpointer data,
+                                      GDestroyNotify notify);
+
+/**
+ * qio_net_listener_wait_client:
+ * @listener: the network listener object
+ *
+ * Block execution of the caller until a new client arrives
+ * on one of the listening sockets. If there was previously
+ * a callback registered with qio_net_listener_set_client_func
+ * it will be temporarily disabled, and re-enabled afterwards.
+ *
+ * Returns: the new client socket
+ */
+QIOChannelSocket *qio_net_listener_wait_client(QIONetListener *listener);
+
+
+/**
+ * qio_net_listener_disconnect:
+ * @listener: the network listener object
+ *
+ * Disconnect the listener, removing all I/O callback
+ * watches and closing the socket channels.
+ */
+void qio_net_listener_disconnect(QIONetListener *listener);
+
+
+/**
+ * qio_net_listener_is_connected:
+ * @listener: the network listener object
+ *
+ * Determine if the listener is connected to any socket
+ * channels
+ *
+ * Returns: true if connected, false otherwise
+ */
+bool qio_net_listener_is_connected(QIONetListener *listener);
+
+#endif /* QIO_NET_LISTENER_H */

io/Makefile.objs

@@ -8,4 +8,5 @@ io-obj-y += channel-watch.o
 io-obj-y += channel-websock.o
 io-obj-y += channel-util.o
 io-obj-y += dns-resolver.o
+io-obj-y += net-listener.o
 io-obj-y += task.o