### Class

# Gio Socket

since: 2.22

#### Description

    class Gio.Socket : GObject.Object
      implements Gio.DatagramBased, Gio.Initable {
      priv: GSocketPrivate*
    }

A `GSocket` is a low-level networking primitive. It is a more or less direct mapping of the BSD socket API in a portable GObject based API. It supports both the UNIX socket implementations and winsock2 on Windows.

`GSocket` is the platform independent base upon which the higher level network primitives are based. Applications are not typically meant to use it directly, but rather through classes like `GSocketClient`, `GSocketService` and `GSocketConnection`. However there may be cases where direct use of `GSocket` is useful.

`GSocket` implements the `GInitable` interface, so if it is manually constructed by e.g. `g_object_new()` you must call `g_initable_init()` and check the results before using the object. This is done automatically in `g_socket_new()` and `g_socket_new_from_fd()`, so these functions can return `NULL`.

Sockets operate in two general modes, blocking or non-blocking. When in blocking mode all operations (which don’t take an explicit blocking parameter) block until the requested operation is finished or there is an error. In non-blocking mode all calls that would block return immediately with a `G_IO_ERROR_WOULD_BLOCK` error. To know when a call would successfully run you can call `g_socket_condition_check()`, or `g_socket_condition_wait()`. You can also use `g_socket_create_source()` and attach it to a `GMainContext` to get callbacks when I/O is possible. Note that all sockets are always set to non blocking mode in the system, and blocking mode is emulated in `GSocket`.

When working in non-blocking mode applications should always be able to handle getting a `G_IO_ERROR_WOULD_BLOCK` error even when some other function said that I/O was possible. This can easily happen in case of a race condition in the application, but it can also happen for other reasons. For instance, on Windows a socket is always seen as writable until a write returns `G_IO_ERROR_WOULD_BLOCK`.

`GSocket`s can be either connection oriented or datagram based. For connection oriented types you must first establish a connection by either connecting to an address or accepting a connection from another address. For connectionless socket types the target/source address is specified or received in each I/O operation.

All socket file descriptors are set to be close-on-exec.

Note that creating a `GSocket` causes the signal `SIGPIPE` to be ignored for the remainder of the program. If you are writing a command-line utility that uses `GSocket`, you may need to take into account the fact that your program will not automatically be killed if it tries to write to `stdout` after it has been closed.

Like most other APIs in GLib, `GSocket` is not inherently thread safe. To use a `GSocket` concurrently from multiple threads, you must implement your own locking.

## Nagle’s algorithm

Since GLib 2.80, `GSocket` will automatically set the `TCP_NODELAY` option on all `G_SOCKET_TYPE_STREAM` sockets. This disables Nagle’s algorithm as it typically does more harm than good on modern networks.

If your application needs Nagle’s algorithm enabled, call `g_socket_set_option()` after constructing a `GSocket` to enable it:

    socket = g_socket_new (…, G_SOCKET_TYPE_STREAM, …);
    if (socket != NULL)
      {
        g_socket_set_option (socket, IPPROTO_TCP, TCP_NODELAY, FALSE, &local_error);
        // handle error if needed
      }

Available since: 2.22

#### Ancestors

- GObject

#### Implements

- GDatagramBased
- GInitable

#### Constructors

###### g_socket_new

Creates a new `GSocket` with the defined family, type and protocol. If `protocol` is 0 (`G_SOCKET_PROTOCOL_DEFAULT`) the default protocol type for the family and type is used.

since: 2.22

###### g_socket_new_from_fd

Creates a new `GSocket` from a native file descriptor or winsock SOCKET handle.

since: 2.22

#### Instance methods

###### g_socket_accept

Accept incoming connections on a connection-based socket. This removes the first outstanding connection request from the listening socket and creates a `GSocket` object for it.

since: 2.22

###### g_socket_bind

When a socket is created it is attached to an address family, but it doesn’t have an address in this family. `g_socket_bind()` assigns the address (sometimes called name) of the socket.

since: 2.22

###### g_socket_check_connect_result

Checks and resets the pending connect error for the socket. This is used to check for errors when `g_socket_connect()` is used in non-blocking mode.

since: 2.22

###### g_socket_close

Closes the socket, shutting down any active connection.

since: 2.22

###### g_socket_condition_check

Checks on the readiness of `socket` to perform operations. The operations specified in `condition` are checked for and masked against the currently-satisfied conditions on `socket`. The result is returned.

since: 2.22

###### g_socket_condition_timed_wait

Waits for up to `timeout_us` microseconds for `condition` to become true on `socket`. If the condition is met, `TRUE` is returned.

since: 2.32

###### g_socket_condition_wait

Waits for `condition` to become true on `socket`. When the condition is met, `TRUE` is returned.

since: 2.22

###### g_socket_connect

Connect the socket to the specified remote address.

since: 2.22

###### g_socket_connection_factory_create_connection

Creates a `GSocketConnection` subclass of the right type for `socket`.

since: 2.22

###### g_socket_create_source

Creates a `GSource` that can be attached to a %GMainContext to monitor for the availability of the specified `condition` on the socket. The `GSource` keeps a reference to the `socket`.

since: 2.22

###### g_socket_get_available_bytes

Get the amount of data pending in the OS input buffer, without blocking.

since: 2.32

###### g_socket_get_blocking

Gets the blocking mode of the socket. For details on blocking I/O, see g_socket_set_blocking().

since: 2.22

###### g_socket_get_broadcast

Gets the broadcast setting on `socket`; if `TRUE`, it is possible to send packets to broadcast addresses.

since: 2.32

###### g_socket_get_credentials

Returns the credentials of the foreign process connected to this socket, if any (e.g. it is only supported for `G_SOCKET_FAMILY_UNIX` sockets).

since: 2.26

###### g_socket_get_family

Gets the socket family of the socket.

since: 2.22

###### g_socket_get_fd

Returns the underlying OS socket object. On unix this is a socket file descriptor, and on Windows this is a Winsock2 SOCKET handle. This may be useful for doing platform specific or otherwise unusual operations on the socket.

since: 2.22

###### g_socket_get_keepalive

Gets the keepalive mode of the socket. For details on this, see g_socket_set_keepalive().

since: 2.22

###### g_socket_get_listen_backlog

Gets the listen backlog setting of the socket. For details on this, see g_socket_set_listen_backlog().

since: 2.22

###### g_socket_get_local_address

Try to get the local address of a bound socket. This is only useful if the socket has been bound to a local address, either explicitly or implicitly when connecting.

since: 2.22

###### g_socket_get_multicast_loopback

Gets the multicast loopback setting on `socket`; if `TRUE` (the default), outgoing multicast packets will be looped back to multicast listeners on the same host.

since: 2.32

###### g_socket_get_multicast_ttl

Gets the multicast time-to-live setting on `socket`; see `g_socket_set_multicast_ttl()` for more details.

since: 2.32

###### g_socket_get_option

Gets the value of an integer-valued option on `socket`, as with getsockopt(). (If you need to fetch a non-integer-valued option, you will need to call `getsockopt()` directly.)

since: 2.36

###### g_socket_get_protocol

Gets the socket protocol id the socket was created with. In case the protocol is unknown, -1 is returned.

since: 2.22

###### g_socket_get_remote_address

Try to get the remote address of a connected socket. This is only useful for connection oriented sockets that have been connected.

since: 2.22

###### g_socket_get_socket_type

Gets the socket type of the socket.

since: 2.22

###### g_socket_get_timeout

Gets the timeout setting of the socket. For details on this, see g_socket_set_timeout().

since: 2.26

###### g_socket_get_ttl

Gets the unicast time-to-live setting on `socket`; see `g_socket_set_ttl()` for more details.

since: 2.32

###### g_socket_is_closed

Checks whether a socket is closed.

since: 2.22

###### g_socket_is_connected

Check whether the socket is connected. This is only useful for connection-oriented sockets.

since: 2.22

###### g_socket_join_multicast_group

Registers `socket` to receive multicast messages sent to `group`. `socket` must be a `G_SOCKET_TYPE_DATAGRAM` socket, and must have been bound to an appropriate interface and port with g_socket_bind().

since: 2.32

###### g_socket_join_multicast_group_ssm

Registers `socket` to receive multicast messages sent to `group`. `socket` must be a `G_SOCKET_TYPE_DATAGRAM` socket, and must have been bound to an appropriate interface and port with g_socket_bind().

since: 2.56

###### g_socket_leave_multicast_group

Removes `socket` from the multicast group defined by `group`, `iface`, and `source_specific` (which must all have the same values they had when you joined the group).

since: 2.32

###### g_socket_leave_multicast_group_ssm

Removes `socket` from the multicast group defined by `group`, `iface`, and `source_specific` (which must all have the same values they had when you joined the group).

since: 2.56

###### g_socket_listen

Marks the socket as a server socket, i.e. a socket that is used to accept incoming requests using g_socket_accept().

since: 2.22

###### g_socket_receive

Receive data (up to `size` bytes) from a socket. This is mainly used by connection-oriented sockets; it is identical to `g_socket_receive_from()` with `address` set to `NULL`.

since: 2.22

###### g_socket_receive_bytes

Receives data (up to `size` bytes) from a socket.

since: 2.80

###### g_socket_receive_bytes_from

Receive data (up to `size` bytes) from a socket.

since: 2.80

###### g_socket_receive_from

Receive data (up to `size` bytes) from a socket.

since: 2.22

###### g_socket_receive_message

Receive data from a socket. For receiving multiple messages, see g_socket_receive_messages(); for easier use, see `g_socket_receive()` and g_socket_receive_from().

since: 2.22

###### g_socket_receive_messages

Receive multiple data messages from `socket` in one go. This is the most complicated and fully-featured version of this call. For easier use, see g_socket_receive(), g_socket_receive_from(), and g_socket_receive_message().

since: 2.48

###### g_socket_receive_with_blocking

This behaves exactly the same as g_socket_receive(), except that the choice of blocking or non-blocking behavior is determined by the `blocking` argument rather than by `socket`‘s properties.

since: 2.26

###### g_socket_send

Tries to send `size` bytes from `buffer` on the socket. This is mainly used by connection-oriented sockets; it is identical to `g_socket_send_to()` with `address` set to `NULL`.

since: 2.22

###### g_socket_send_message

Send data to `address` on `socket`. For sending multiple messages see g_socket_send_messages(); for easier use, see `g_socket_send()` and g_socket_send_to().

since: 2.22

###### g_socket_send_message_with_timeout

This behaves exactly the same as g_socket_send_message(), except that the choice of timeout behavior is determined by the `timeout_us` argument rather than by `socket`‘s properties.

since: 2.60

###### g_socket_send_messages

Send multiple data messages from `socket` in one go. This is the most complicated and fully-featured version of this call. For easier use, see g_socket_send(), g_socket_send_to(), and g_socket_send_message().

since: 2.44

###### g_socket_send_to

Tries to send `size` bytes from `buffer` to `address`. If `address` is `NULL` then the message is sent to the default receiver (set by g_socket_connect()).

since: 2.22

###### g_socket_send_with_blocking

This behaves exactly the same as g_socket_send(), except that the choice of blocking or non-blocking behavior is determined by the `blocking` argument rather than by `socket`‘s properties.

since: 2.26

###### g_socket_set_blocking

Sets the blocking mode of the socket. In blocking mode all operations (which don’t take an explicit blocking parameter) block until they succeed or there is an error. In non-blocking mode all functions return results immediately or with a `G_IO_ERROR_WOULD_BLOCK` error.

since: 2.22

###### g_socket_set_broadcast

Sets whether `socket` should allow sending to broadcast addresses. This is `FALSE` by default.

since: 2.32

###### g_socket_set_keepalive

Sets or unsets the `SO_KEEPALIVE` flag on the underlying socket. When this flag is set on a socket, the system will attempt to verify that the remote socket endpoint is still present if a sufficiently long period of time passes with no data being exchanged. If the system is unable to verify the presence of the remote endpoint, it will automatically close the connection.

since: 2.22

###### g_socket_set_listen_backlog

Sets the maximum number of outstanding connections allowed when listening on this socket. If more clients than this are connecting to the socket and the application is not handling them on time then the new connections will be refused.

since: 2.22

###### g_socket_set_multicast_loopback

Sets whether outgoing multicast packets will be received by sockets listening on that multicast address on the same host. This is `TRUE` by default.

since: 2.32

###### g_socket_set_multicast_ttl

Sets the time-to-live for outgoing multicast datagrams on `socket`. By default, this is 1, meaning that multicast packets will not leave the local network.

since: 2.32

###### g_socket_set_option

Sets the value of an integer-valued option on `socket`, as with setsockopt(). (If you need to set a non-integer-valued option, you will need to call `setsockopt()` directly.)

since: 2.36

###### g_socket_set_timeout

Sets the time in seconds after which I/O operations on `socket` will time out if they have not yet completed.

since: 2.26

###### g_socket_set_ttl

Sets the time-to-live for outgoing unicast packets on `socket`. By default the platform-specific default value is used.

since: 2.32

###### g_socket_shutdown

Shut down part or all of a full-duplex connection.

since: 2.22

###### g_socket_speaks_ipv4

Checks if a socket is capable of speaking IPv4.

since: 2.22

##### Methods inherited from GObject (43)

Please see GObject for a full list of methods.

##### Methods inherited from GDatagramBased (5)

###### g_datagram_based_condition_check

Checks on the readiness of `datagram_based` to perform operations. The operations specified in `condition` are checked for and masked against the currently-satisfied conditions on `datagram_based`. The result is returned.

since: 2.48

###### g_datagram_based_condition_wait

Waits for up to `timeout` microseconds for condition to become true on `datagram_based`. If the condition is met, `TRUE` is returned.

since: 2.48

###### g_datagram_based_create_source

Creates a `GSource` that can be attached to a `GMainContext` to monitor for the availability of the specified `condition` on the `GDatagramBased`. The `GSource` keeps a reference to the `datagram_based`.

since: 2.48

###### g_datagram_based_receive_messages

Receive one or more data messages from `datagram_based` in one go.

since: 2.48

###### g_datagram_based_send_messages

Send one or more data messages from `datagram_based` in one go.

since: 2.48

##### Methods inherited from GInitable (1)

###### g_initable_init

Initializes the object implementing the interface.

since: 2.22

#### Properties

###### Gio.Socket:blocking

Whether I/O on this socket is blocking.

since: 2.22

###### Gio.Socket:broadcast

Whether the socket should allow sending to broadcast addresses.

since: 2.32

###### Gio.Socket:family

The socket’s address family.

since: 2.22

###### Gio.Socket:fd

The socket’s file descriptor.

since: 2.22

###### Gio.Socket:keepalive

Whether to keep the connection alive by sending periodic pings.

since: 2.22

###### Gio.Socket:listen-backlog

The number of outstanding connections in the listen queue.

since: 2.22

###### Gio.Socket:local-address

The local address the socket is bound to.

since: 2.22

###### Gio.Socket:multicast-loopback

Whether outgoing multicast packets loop back to the local host.

since: 2.32

###### Gio.Socket:multicast-ttl

Time-to-live out outgoing multicast packets.

since: 2.32

###### Gio.Socket:protocol

The ID of the protocol to use, or `-1` for unknown.

since: 2.22

###### Gio.Socket:remote-address

The remote address the socket is connected to.

since: 2.22

###### Gio.Socket:timeout

The timeout in seconds on socket I/O.

since: 2.26

###### Gio.Socket:ttl

Time-to-live for outgoing unicast packets.

since: 2.32

###### Gio.Socket:type

The socket’s type.

since: 2.22

#### Signals

##### Signals inherited from GObject (1)

###### GObject::notify

The notify signal is emitted on an object when one of its properties has its value set through g_object_set_property(), g_object_set(), et al.

since: 2.0

#### Class structure

    struct GioSocketClass {
      GObjectClass parent_class;
      void (* _g_reserved1) (
    void
      );
      void (* _g_reserved2) (
    void
      );
      void (* _g_reserved3) (
    void
      );
      void (* _g_reserved4) (
    void
      );
      void (* _g_reserved5) (
    void
      );
      void (* _g_reserved6) (
    void
      );
      void (* _g_reserved7) (
    void
      );
      void (* _g_reserved8) (
    void
      );
      void (* _g_reserved9) (
    void
      );
      void (* _g_reserved10) (
    void
      );

    }

No description available.

###### Class members

`parent_class: GObjectClass`
  No description available.
`_g_reserved1: void (* _g_reserved1) ( void )`
  No description available.
`_g_reserved2: void (* _g_reserved2) ( void )`
  No description available.
`_g_reserved3: void (* _g_reserved3) ( void )`
  No description available.
`_g_reserved4: void (* _g_reserved4) ( void )`
  No description available.
`_g_reserved5: void (* _g_reserved5) ( void )`
  No description available.
`_g_reserved6: void (* _g_reserved6) ( void )`
  No description available.
`_g_reserved7: void (* _g_reserved7) ( void )`
  No description available.
`_g_reserved8: void (* _g_reserved8) ( void )`
  No description available.
`_g_reserved9: void (* _g_reserved9) ( void )`
  No description available.
`_g_reserved10: void (* _g_reserved10) ( void )`
  No description available.