## GSocketListener

GSocketListener — Helper for accepting network client connections

## Synopsis

                        GSocketListener;
    GSocketListener *   g_socket_listener_new               (void);
    gboolean            g_socket_listener_add_socket        (GSocketListener *listener,
                                                             GSocket *socket,
                                                             GObject *source_object,
                                                             GError **error);
    gboolean            g_socket_listener_add_address       (GSocketListener *listener,
                                                             GSocketAddress *address,
                                                             GSocketType type,
                                                             GSocketProtocol protocol,
                                                             GObject *source_object,
                                                             GSocketAddress **effective_address,
                                                             GError **error);
    gboolean            g_socket_listener_add_inet_port     (GSocketListener *listener,
                                                             guint16 port,
                                                             GObject *source_object,
                                                             GError **error);
    guint16             g_socket_listener_add_any_inet_port (GSocketListener *listener,
                                                             GObject *source_object,
                                                             GError **error);
    GSocketConnection * g_socket_listener_accept            (GSocketListener *listener,
                                                             GObject **source_object,
                                                             GCancellable *cancellable,
                                                             GError **error);
    void                g_socket_listener_accept_async      (GSocketListener *listener,
                                                             GCancellable *cancellable,
                                                             GAsyncReadyCallback callback,
                                                             gpointer user_data);
    GSocketConnection * g_socket_listener_accept_finish     (GSocketListener *listener,
                                                             GAsyncResult *result,
                                                             GObject **source_object,
                                                             GError **error);
    GSocket *           g_socket_listener_accept_socket     (GSocketListener *listener,
                                                             GObject **source_object,
                                                             GCancellable *cancellable,
                                                             GError **error);
    void                g_socket_listener_accept_socket_async
                                                            (GSocketListener *listener,
                                                             GCancellable *cancellable,
                                                             GAsyncReadyCallback callback,
                                                             gpointer user_data);
    GSocket *           g_socket_listener_accept_socket_finish
                                                            (GSocketListener *listener,
                                                             GAsyncResult *result,
                                                             GObject **source_object,
                                                             GError **error);
    void                g_socket_listener_close             (GSocketListener *listener);
    void                g_socket_listener_set_backlog       (GSocketListener *listener,
                                                             int listen_backlog);

## Object Hierarchy

      GObject
       +----GSocketListener
             +----GSocketService

## Properties

      "listen-backlog"           gint                  : Read / Write / Construct

## Description

A GSocketListener is an object that keeps track of a set of server sockets and helps you accept sockets from any of the socket, either sync or async.

If you want to implement a network server, also look at GSocketService and GThreadedSocketService which are subclass of GSocketListener that makes this even easier.

## Details

### GSocketListener

    typedef struct _GSocketListener GSocketListener;

### g_socket_listener_new ()

    GSocketListener *   g_socket_listener_new               (void);

Creates a new GSocketListener with no sockets to listen for. New listeners can be added with e.g. `g_socket_listener_add_address()` or `g_socket_listener_add_inet_port()`.

Returns : | a new GSocketListener.

Since 2.22

### g_socket_listener_add_socket ()

    gboolean            g_socket_listener_add_socket        (GSocketListener *listener,
                                                             GSocket *socket,
                                                             GObject *source_object,
                                                             GError **error);

Adds `socket` to the set of sockets that we try to accept new clients from. The socket must be bound to a local address and listened to.

`source_object` will be passed out in the various calls to accept to identify this particular source, which is useful if you're listening on multiple addresses and do different things depending on what address is connected to.

`listener` : | a GSocketListener
`socket` : | a listening GSocket
`source_object` : | Optional GObject identifying this source
`error` : | GError for error reporting, or `NULL` to ignore.
Returns : | `TRUE` on success, `FALSE` on error.

Since 2.22

### g_socket_listener_add_address ()

    gboolean            g_socket_listener_add_address       (GSocketListener *listener,
                                                             GSocketAddress *address,
                                                             GSocketType type,
                                                             GSocketProtocol protocol,
                                                             GObject *source_object,
                                                             GSocketAddress **effective_address,
                                                             GError **error);

Creates a socket of type `type` and protocol `protocol`, binds it to `address` and adds it to the set of sockets we're accepting sockets from.

Note that adding an IPv6 address, depending on the platform, may or may not result in a listener that also accepts IPv4 connections. For more determinstic behaviour, see `g_socket_listener_add_inet_port()`.

`source_object` will be passed out in the various calls to accept to identify this particular source, which is useful if you're listening on multiple addresses and do different things depending on what address is connected to.

If successful and `effective_address` is non-`NULL` then it will be set to the address that the binding actually occured at. This is helpful for determining the port number that was used for when requesting a binding to port 0 (ie: "any port"). This address, if requested, belongs to the caller and must be freed.

`listener` : | a GSocketListener
`address` : | a GSocketAddress
`type` : | a GSocketType
`protocol` : | a GSocketProtocol
`source_object` : | Optional GObject identifying this source
`effective_address` : | location to store the address that was bound to, or `NULL`. [out][allow-none]
`error` : | GError for error reporting, or `NULL` to ignore.
Returns : | `TRUE` on success, `FALSE` on error.

Since 2.22

### g_socket_listener_add_inet_port ()

    gboolean            g_socket_listener_add_inet_port     (GSocketListener *listener,
                                                             guint16 port,
                                                             GObject *source_object,
                                                             GError **error);

Helper function for `g_socket_listener_add_address()` that creates a TCP/IP socket listening on IPv4 and IPv6 (if supported) on the specified port on all interfaces.

`source_object` will be passed out in the various calls to accept to identify this particular source, which is useful if you're listening on multiple addresses and do different things depending on what address is connected to.

`listener` : | a GSocketListener
`port` : | an IP port number (non-zero)
`source_object` : | Optional GObject identifying this source
`error` : | GError for error reporting, or `NULL` to ignore.
Returns : | `TRUE` on success, `FALSE` on error.

Since 2.22

### g_socket_listener_add_any_inet_port ()

    guint16             g_socket_listener_add_any_inet_port (GSocketListener *listener,
                                                             GObject *source_object,
                                                             GError **error);

Listens for TCP connections on any available port number for both IPv6 and IPv4 (if each are available).

This is useful if you need to have a socket for incoming connections but don't care about the specific port number.

`source_object` will be passed out in the various calls to accept to identify this particular source, which is useful if you're listening on multiple addresses and do different things depending on what address is connected to.

`listener` : | a GSocketListener
`source_object` : | Optional GObject identifying this source
`error` : | a GError location to store the error occuring, or `NULL` to ignore.
Returns : | the port number, or 0 in case of failure.

Since 2.24

### g_socket_listener_accept ()

    GSocketConnection * g_socket_listener_accept            (GSocketListener *listener,
                                                             GObject **source_object,
                                                             GCancellable *cancellable,
                                                             GError **error);

Blocks waiting for a client to connect to any of the sockets added to the listener. Returns a GSocketConnection for the socket that was accepted.

If `source_object` is not `NULL` it will be filled out with the source object specified when the corresponding socket or address was added to the listener.

If `cancellable` is not `NULL`, then the operation can be cancelled by triggering the cancellable object from another thread. If the operation was cancelled, the error `G_IO_ERROR_CANCELLED` will be returned.

`listener` : | a GSocketListener
`source_object` : | location where GObject pointer will be stored, or `NULL`. [out][transfer none][allow-none]
`cancellable` : | optional GCancellable object, `NULL` to ignore.
`error` : | GError for error reporting, or `NULL` to ignore.
Returns : | a GSocketConnection on success, `NULL` on error.

Since 2.22

### g_socket_listener_accept_async ()

    void                g_socket_listener_accept_async      (GSocketListener *listener,
                                                             GCancellable *cancellable,
                                                             GAsyncReadyCallback callback,
                                                             gpointer user_data);

This is the asynchronous version of `g_socket_listener_accept()`.

When the operation is finished `callback` will be called. You can then call `g_socket_listener_accept_socket()` to get the result of the operation.

`listener` : | a GSocketListener
`cancellable` : | a GCancellable, or `NULL`
`callback` : | a GAsyncReadyCallback
`user_data` : | user data for the callback

Since 2.22

### g_socket_listener_accept_finish ()

    GSocketConnection * g_socket_listener_accept_finish     (GSocketListener *listener,
                                                             GAsyncResult *result,
                                                             GObject **source_object,
                                                             GError **error);

Finishes an async accept operation. See `g_socket_listener_accept_async()`

`listener` : | a GSocketListener
`result` : | a GAsyncResult.
`source_object` : | Optional GObject identifying this source
`error` : | a GError location to store the error occuring, or `NULL` to ignore.
Returns : | a GSocketConnection on success, `NULL` on error.

Since 2.22

### g_socket_listener_accept_socket ()

    GSocket *           g_socket_listener_accept_socket     (GSocketListener *listener,
                                                             GObject **source_object,
                                                             GCancellable *cancellable,
                                                             GError **error);

Blocks waiting for a client to connect to any of the sockets added to the listener. Returns the GSocket that was accepted.

If you want to accept the high-level GSocketConnection, not a GSocket, which is often the case, then you should use `g_socket_listener_accept()` instead.

If `source_object` is not `NULL` it will be filled out with the source object specified when the corresponding socket or address was added to the listener.

If `cancellable` is not `NULL`, then the operation can be cancelled by triggering the cancellable object from another thread. If the operation was cancelled, the error `G_IO_ERROR_CANCELLED` will be returned.

`listener` : | a GSocketListener
`source_object` : | location where GObject pointer will be stored, or `NULL`. [out][transfer none][allow-none]
`cancellable` : | optional GCancellable object, `NULL` to ignore.
`error` : | GError for error reporting, or `NULL` to ignore.
Returns : | a GSocket on success, `NULL` on error.

Since 2.22

### g_socket_listener_accept_socket_async ()

    void                g_socket_listener_accept_socket_async
                                                            (GSocketListener *listener,
                                                             GCancellable *cancellable,
                                                             GAsyncReadyCallback callback,
                                                             gpointer user_data);

This is the asynchronous version of `g_socket_listener_accept_socket()`.

When the operation is finished `callback` will be called. You can then call `g_socket_listener_accept_socket_finish()` to get the result of the operation.

`listener` : | a GSocketListener
`cancellable` : | a GCancellable, or `NULL`
`callback` : | a GAsyncReadyCallback
`user_data` : | user data for the callback

Since 2.22

### g_socket_listener_accept_socket_finish ()

    GSocket *           g_socket_listener_accept_socket_finish
                                                            (GSocketListener *listener,
                                                             GAsyncResult *result,
                                                             GObject **source_object,
                                                             GError **error);

Finishes an async accept operation. See `g_socket_listener_accept_socket_async()`

`listener` : | a GSocketListener
`result` : | a GAsyncResult.
`source_object` : | Optional GObject identifying this source
`error` : | a GError location to store the error occuring, or `NULL` to ignore.
Returns : | a GSocket on success, `NULL` on error.

Since 2.22

### g_socket_listener_close ()

    void                g_socket_listener_close             (GSocketListener *listener);

Closes all the sockets in the listener.

`listener` : | a GSocketListener

Since 2.22

### g_socket_listener_set_backlog ()

    void                g_socket_listener_set_backlog       (GSocketListener *listener,
                                                             int listen_backlog);

Sets the listen backlog on the sockets in the listener.

See `g_socket_set_listen_backlog()` for details

`listener` : | a GSocketListener
`listen_backlog` : | an integer

Since 2.22

## Property Details

### The `"listen-backlog"` property

      "listen-backlog"           gint                  : Read / Write / Construct

outstanding connections in the listen queue.

Allowed values: [0,2000]

Default value: 10

## See Also

GThreadedSocketService, GSocketService.