Class

GioSocket

since: 2.22

Description [src]

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.

GSockets 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

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 GInitable (1)

g_initable_init

Initializes the object implementing the interface.

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.

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.

Description [src]

Nagle’s algorithm

Ancestors

Implements

Constructors

Instance methods

Methods inherited from GObject (43)

Methods inherited from GDatagramBased (5)

Methods inherited from GInitable (1)

Properties

Signals

Signals inherited from GObject (1)

Class structure

Class members