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GSocket

GSocket — Low-level socket object

Functions

gboolean (*GSocketSourceFunc) ()
GSocket * g_socket_new ()
GSocket * g_socket_new_from_fd ()
gboolean g_socket_bind ()
gboolean g_socket_listen ()
GSocket * g_socket_accept ()
gboolean g_socket_connect ()
gboolean g_socket_check_connect_result ()
gssize g_socket_receive ()
gssize g_socket_receive_from ()
gssize g_socket_receive_message ()
gint g_socket_receive_messages ()
gssize g_socket_receive_with_blocking ()
gssize g_socket_send ()
gssize g_socket_send_to ()
gssize g_socket_send_message ()
gint g_socket_send_messages ()
gssize g_socket_send_with_blocking ()
gboolean g_socket_close ()
gboolean g_socket_is_closed ()
gboolean g_socket_shutdown ()
gboolean g_socket_is_connected ()
GSource * g_socket_create_source ()
GIOCondition g_socket_condition_check ()
gboolean g_socket_condition_wait ()
gboolean g_socket_condition_timed_wait ()
gssize g_socket_get_available_bytes ()
void g_socket_set_listen_backlog ()
gint g_socket_get_listen_backlog ()
gboolean g_socket_get_blocking ()
void g_socket_set_blocking ()
gboolean g_socket_get_keepalive ()
void g_socket_set_keepalive ()
guint g_socket_get_timeout ()
void g_socket_set_timeout ()
void g_socket_set_ttl ()
guint g_socket_get_ttl ()
gboolean g_socket_get_broadcast ()
void g_socket_set_broadcast ()
gboolean g_socket_get_option ()
gboolean g_socket_set_option ()
GSocketFamily g_socket_get_family ()
int g_socket_get_fd ()
GSocketAddress * g_socket_get_local_address ()
GSocketProtocol g_socket_get_protocol ()
GSocketAddress * g_socket_get_remote_address ()
GSocketType g_socket_get_socket_type ()
gboolean g_socket_speaks_ipv4 ()
GCredentials * g_socket_get_credentials ()
gboolean g_socket_join_multicast_group ()
gboolean g_socket_leave_multicast_group ()
gboolean g_socket_get_multicast_loopback ()
void g_socket_set_multicast_loopback ()
guint g_socket_get_multicast_ttl ()
void g_socket_set_multicast_ttl ()

Properties

gboolean blocking Read / Write
gboolean broadcast Read / Write
GSocketFamily family Read / Write / Construct Only
gint fd Read / Write / Construct Only
gboolean keepalive Read / Write
gint listen-backlog Read / Write
GSocketAddress * local-address Read
gboolean multicast-loopback Read / Write
guint multicast-ttl Read / Write
GSocketProtocol protocol Read / Write / Construct Only
GSocketAddress * remote-address Read
guint timeout Read / Write
guint ttl Read / Write
GSocketType type Read / Write / Construct Only

Types and Values

Object Hierarchy

    GObject
    ╰── GSocket

Implemented Interfaces

GSocket implements GInitable and GDatagramBased.

Includes

#include <gio/gio.h>

Description

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.

Functions

GSocketSourceFunc ()

gboolean
(*GSocketSourceFunc) (GSocket *socket,
                      GIOCondition condition,
                      gpointer user_data);

This is the function type of the callback used for the GSource returned by g_socket_create_source().

Parameters

socket

the GSocket

 

condition

the current condition at the source fired.

 

user_data

data passed in by the user.

 

Returns

it should return FALSE if the source should be removed.

Since: 2.22


g_socket_new ()

GSocket *
g_socket_new (GSocketFamily family,
              GSocketType type,
              GSocketProtocol protocol,
              GError **error);

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.

The protocol is a family and type specific int that specifies what kind of protocol to use. GSocketProtocol lists several common ones. Many families only support one protocol, and use 0 for this, others support several and using 0 means to use the default protocol for the family and type.

The protocol id is passed directly to the operating system, so you can use protocols not listed in GSocketProtocol if you know the protocol number used for it.

Parameters

family

the socket family to use, e.g. G_SOCKET_FAMILY_IPV4.

 

type

the socket type to use.

 

protocol

the id of the protocol to use, or 0 for default.

 

error

GError for error reporting, or NULL to ignore.

 

Returns

a GSocket or NULL on error. Free the returned object with g_object_unref().

Since: 2.22


g_socket_new_from_fd ()

GSocket *
g_socket_new_from_fd (gint fd,
                      GError **error);

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

This reads all the settings from the file descriptor so that all properties should work. Note that the file descriptor will be set to non-blocking mode, independent on the blocking mode of the GSocket.

On success, the returned GSocket takes ownership of fd . On failure, the caller must close fd themselves.

Since GLib 2.46, it is no longer a fatal error to call this on a non-socket descriptor. Instead, a GError will be set with code G_IO_ERROR_FAILED

Parameters

fd

a native socket file descriptor.

 

error

GError for error reporting, or NULL to ignore.

 

Returns

a GSocket or NULL on error. Free the returned object with g_object_unref().

Since: 2.22


g_socket_bind ()

gboolean
g_socket_bind (GSocket *socket,
               GSocketAddress *address,
               gboolean allow_reuse,
               GError **error);

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.

It is generally required to bind to a local address before you can receive connections. (See g_socket_listen() and g_socket_accept() ). In certain situations, you may also want to bind a socket that will be used to initiate connections, though this is not normally required.

If socket is a TCP socket, then allow_reuse controls the setting of the SO_REUSEADDR socket option; normally it should be TRUE for server sockets (sockets that you will eventually call g_socket_accept() on), and FALSE for client sockets. (Failing to set this flag on a server socket may cause g_socket_bind() to return G_IO_ERROR_ADDRESS_IN_USE if the server program is stopped and then immediately restarted.)

If socket is a UDP socket, then allow_reuse determines whether or not other UDP sockets can be bound to the same address at the same time. In particular, you can have several UDP sockets bound to the same address, and they will all receive all of the multicast and broadcast packets sent to that address. (The behavior of unicast UDP packets to an address with multiple listeners is not defined.)

Parameters

socket

a GSocket.

 

address

a GSocketAddress specifying the local address.

 

allow_reuse

whether to allow reusing this address

 

error

GError for error reporting, or NULL to ignore.

 

Returns

TRUE on success, FALSE on error.

Since: 2.22


g_socket_listen ()

gboolean
g_socket_listen (GSocket *socket,
                 GError **error);

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

Before calling this the socket must be bound to a local address using g_socket_bind().

To set the maximum amount of outstanding clients, use g_socket_set_listen_backlog().

Parameters

socket

a GSocket.

 

error

GError for error reporting, or NULL to ignore.

 

Returns

TRUE on success, FALSE on error.

Since: 2.22


g_socket_accept ()

GSocket *
g_socket_accept (GSocket *socket,
                 GCancellable *cancellable,
                 GError **error);

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.

The socket must be bound to a local address with g_socket_bind() and must be listening for incoming connections (g_socket_listen()).

If there are no outstanding connections then the operation will block or return G_IO_ERROR_WOULD_BLOCK if non-blocking I/O is enabled. To be notified of an incoming connection, wait for the G_IO_IN condition.

Parameters

socket

a GSocket.

 

cancellable

a GCancellable or NULL.

[nullable]

error

GError for error reporting, or NULL to ignore.

 

Returns

a new GSocket, or NULL on error. Free the returned object with g_object_unref().

[transfer full]

Since: 2.22


g_socket_connect ()

gboolean
g_socket_connect (GSocket *socket,
                  GSocketAddress *address,
                  GCancellable *cancellable,
                  GError **error);

Connect the socket to the specified remote address.

For connection oriented socket this generally means we attempt to make a connection to the address . For a connection-less socket it sets the default address for g_socket_send() and discards all incoming datagrams from other sources.

Generally connection oriented sockets can only connect once, but connection-less sockets can connect multiple times to change the default address.

If the connect call needs to do network I/O it will block, unless non-blocking I/O is enabled. Then G_IO_ERROR_PENDING is returned and the user can be notified of the connection finishing by waiting for the G_IO_OUT condition. The result of the connection must then be checked with g_socket_check_connect_result().

Parameters

socket

a GSocket.

 

address

a GSocketAddress specifying the remote address.

 

cancellable

a GCancellable or NULL.

[nullable]

error

GError for error reporting, or NULL to ignore.

 

Returns

TRUE if connected, FALSE on error.

Since: 2.22


g_socket_check_connect_result ()

gboolean
g_socket_check_connect_result (GSocket *socket,
                               GError **error);

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.

Parameters

socket

a GSocket

 

error

GError for error reporting, or NULL to ignore.

 

Returns

TRUE if no error, FALSE otherwise, setting error to the error

Since: 2.22


g_socket_receive ()

gssize
g_socket_receive (GSocket *socket,
                  gchar *buffer,
                  gsize size,
                  GCancellable *cancellable,
                  GError **error);

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.

For G_SOCKET_TYPE_DATAGRAM and G_SOCKET_TYPE_SEQPACKET sockets, g_socket_receive() will always read either 0 or 1 complete messages from the socket. If the received message is too large to fit in buffer , then the data beyond size bytes will be discarded, without any explicit indication that this has occurred.

For G_SOCKET_TYPE_STREAM sockets, g_socket_receive() can return any number of bytes, up to size . If more than size bytes have been received, the additional data will be returned in future calls to g_socket_receive().

If the socket is in blocking mode the call will block until there is some data to receive, the connection is closed, or there is an error. If there is no data available and the socket is in non-blocking mode, a G_IO_ERROR_WOULD_BLOCK error will be returned. To be notified when data is available, wait for the G_IO_IN condition.

On error -1 is returned and error is set accordingly.

Parameters

socket

a GSocket

 

buffer

a buffer to read data into (which should be at least size bytes long).

[array length=size][element-type guint8]

size

the number of bytes you want to read from the socket

 

cancellable

a GCancellable or NULL.

[nullable]

error

GError for error reporting, or NULL to ignore.

 

Returns

Number of bytes read, or 0 if the connection was closed by the peer, or -1 on error

Since: 2.22


g_socket_receive_from ()

gssize
g_socket_receive_from (GSocket *socket,
                       GSocketAddress **address,
                       gchar *buffer,
                       gsize size,
                       GCancellable *cancellable,
                       GError **error);

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

If address is non-NULL then address will be set equal to the source address of the received packet. address is owned by the caller.

See g_socket_receive() for additional information.

Parameters

socket

a GSocket

 

address

a pointer to a GSocketAddress pointer, or NULL.

[out][optional]

buffer

a buffer to read data into (which should be at least size bytes long).

[array length=size][element-type guint8]

size

the number of bytes you want to read from the socket

 

cancellable

a GCancellable or NULL.

[nullable]

error

GError for error reporting, or NULL to ignore.

 

Returns

Number of bytes read, or 0 if the connection was closed by the peer, or -1 on error

Since: 2.22


g_socket_receive_message ()

gssize
g_socket_receive_message (GSocket *socket,
                          GSocketAddress **address,
                          GInputVector *vectors,
                          gint num_vectors,
                          GSocketControlMessage ***messages,
                          gint *num_messages,
                          gint *flags,
                          GCancellable *cancellable,
                          GError **error);

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().

If address is non-NULL then address will be set equal to the source address of the received packet. address is owned by the caller.

vector must point to an array of GInputVector structs and num_vectors must be the length of this array. These structs describe the buffers that received data will be scattered into. If num_vectors is -1, then vectors is assumed to be terminated by a GInputVector with a NULL buffer pointer.

As a special case, if num_vectors is 0 (in which case, vectors may of course be NULL), then a single byte is received and discarded. This is to facilitate the common practice of sending a single '\0' byte for the purposes of transferring ancillary data.

messages , if non-NULL, will be set to point to a newly-allocated array of GSocketControlMessage instances or NULL if no such messages was received. These correspond to the control messages received from the kernel, one GSocketControlMessage per message from the kernel. This array is NULL-terminated and must be freed by the caller using g_free() after calling g_object_unref() on each element. If messages is NULL, any control messages received will be discarded.

num_messages , if non-NULL, will be set to the number of control messages received.

If both messages and num_messages are non-NULL, then num_messages gives the number of GSocketControlMessage instances in messages (ie: not including the NULL terminator).

flags is an in/out parameter. The commonly available arguments for this are available in the GSocketMsgFlags enum, but the values there are the same as the system values, and the flags are passed in as-is, so you can pass in system-specific flags too (and g_socket_receive_message() may pass system-specific flags out). Flags passed in to the parameter affect the receive operation; flags returned out of it are relevant to the specific returned message.

As with g_socket_receive(), data may be discarded if socket is G_SOCKET_TYPE_DATAGRAM or G_SOCKET_TYPE_SEQPACKET and you do not provide enough buffer space to read a complete message. You can pass G_SOCKET_MSG_PEEK in flags to peek at the current message without removing it from the receive queue, but there is no portable way to find out the length of the message other than by reading it into a sufficiently-large buffer.

If the socket is in blocking mode the call will block until there is some data to receive, the connection is closed, or there is an error. If there is no data available and the socket is in non-blocking mode, a G_IO_ERROR_WOULD_BLOCK error will be returned. To be notified when data is available, wait for the G_IO_IN condition.

On error -1 is returned and error is set accordingly.

Parameters

socket

a GSocket

 

address

a pointer to a GSocketAddress pointer, or NULL.

[out][optional]

vectors

an array of GInputVector structs.

[array length=num_vectors]

num_vectors

the number of elements in vectors , or -1

 

messages

a pointer which may be filled with an array of GSocketControlMessages, or NULL.

[array length=num_messages][out][optional][nullable]

num_messages

a pointer which will be filled with the number of elements in messages , or NULL.

[out]

flags

a pointer to an int containing GSocketMsgFlags flags.

[inout]

cancellable

a GCancellable or NULL

 

error

a GError pointer, or NULL

 

Returns

Number of bytes read, or 0 if the connection was closed by the peer, or -1 on error

Since: 2.22


g_socket_receive_messages ()

gint
g_socket_receive_messages (GSocket *socket,
                           GInputMessage *messages,
                           guint num_messages,
                           gint flags,
                           GCancellable *cancellable,
                           GError **error);

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().

messages must point to an array of GInputMessage structs and num_messages must be the length of this array. Each GInputMessage contains a pointer to an array of GInputVector structs describing the buffers that the data received in each message will be written to. Using multiple GInputVectors is more memory-efficient than manually copying data out of a single buffer to multiple sources, and more system-call-efficient than making multiple calls to g_socket_receive(), such as in scenarios where a lot of data packets need to be received (e.g. high-bandwidth video streaming over RTP/UDP).

flags modify how all messages are received. The commonly available arguments for this are available in the GSocketMsgFlags enum, but the values there are the same as the system values, and the flags are passed in as-is, so you can pass in system-specific flags too. These flags affect the overall receive operation. Flags affecting individual messages are returned in GInputMessage.flags.

The other members of GInputMessage are treated as described in its documentation.

If “blocking” is TRUE the call will block until num_messages have been received, or the end of the stream is reached.

If “blocking” is FALSE the call will return up to num_messages without blocking, or G_IO_ERROR_WOULD_BLOCK if no messages are queued in the operating system to be received.

In blocking mode, if “timeout” is positive and is reached before any messages are received, G_IO_ERROR_TIMED_OUT is returned, otherwise up to num_messages are returned. (Note: This is effectively the behaviour of MSG_WAITFORONE with recvmmsg().)

To be notified when messages are available, wait for the G_IO_IN condition. Note though that you may still receive G_IO_ERROR_WOULD_BLOCK from g_socket_receive_messages() even if you were previously notified of a G_IO_IN condition.

If the remote peer closes the connection, any messages queued in the operating system will be returned, and subsequent calls to g_socket_receive_messages() will return 0 (with no error set).

On error -1 is returned and error is set accordingly. An error will only be returned if zero messages could be received; otherwise the number of messages successfully received before the error will be returned.

Parameters

socket

a GSocket

 

messages

an array of GInputMessage structs.

[array length=num_messages]

num_messages

the number of elements in messages

 

flags

an int containing GSocketMsgFlags flags for the overall operation

 

cancellable

a GCancellable or NULL.

[nullable]

error

GError for error reporting, or NULL to ignore

 

Returns

number of messages received, or -1 on error. Note that the number of messages received may be smaller than num_messages if in non-blocking mode, if the peer closed the connection, or if num_messages was larger than UIO_MAXIOV (1024), in which case the caller may re-try to receive the remaining messages.

Since: 2.48


g_socket_receive_with_blocking ()

gssize
g_socket_receive_with_blocking (GSocket *socket,
                                gchar *buffer,
                                gsize size,
                                gboolean blocking,
                                GCancellable *cancellable,
                                GError **error);

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.

Parameters

socket

a GSocket

 

buffer

a buffer to read data into (which should be at least size bytes long).

[array length=size][element-type guint8]

size

the number of bytes you want to read from the socket

 

blocking

whether to do blocking or non-blocking I/O

 

cancellable

a GCancellable or NULL.

[nullable]

error

GError for error reporting, or NULL to ignore.

 

Returns

Number of bytes read, or 0 if the connection was closed by the peer, or -1 on error

Since: 2.26


g_socket_send ()

gssize
g_socket_send (GSocket *socket,
               const gchar *buffer,
               gsize size,
               GCancellable *cancellable,
               GError **error);

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.

If the socket is in blocking mode the call will block until there is space for the data in the socket queue. If there is no space available and the socket is in non-blocking mode a G_IO_ERROR_WOULD_BLOCK error will be returned. To be notified when space is available, wait for the G_IO_OUT condition. Note though that you may still receive G_IO_ERROR_WOULD_BLOCK from g_socket_send() even if you were previously notified of a G_IO_OUT condition. (On Windows in particular, this is very common due to the way the underlying APIs work.)

On error -1 is returned and error is set accordingly.

Parameters

socket

a GSocket

 

buffer

the buffer containing the data to send.

[array length=size][element-type guint8]

size

the number of bytes to send

 

cancellable

a GCancellable or NULL.

[nullable]

error

GError for error reporting, or NULL to ignore.

 

Returns

Number of bytes written (which may be less than size ), or -1 on error

Since: 2.22


g_socket_send_to ()

gssize
g_socket_send_to (GSocket *socket,
                  GSocketAddress *address,
                  const gchar *buffer,
                  gsize size,
                  GCancellable *cancellable,
                  GError **error);

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()).

See g_socket_send() for additional information.

Parameters

socket

a GSocket

 

address

a GSocketAddress, or NULL.

[nullable]

buffer

the buffer containing the data to send.

[array length=size][element-type guint8]

size

the number of bytes to send

 

cancellable

a GCancellable or NULL.

[nullable]

error

GError for error reporting, or NULL to ignore.

 

Returns

Number of bytes written (which may be less than size ), or -1 on error

Since: 2.22


g_socket_send_message ()

gssize
g_socket_send_message (GSocket *socket,
                       GSocketAddress *address,
                       GOutputVector *vectors,
                       gint num_vectors,
                       GSocketControlMessage **messages,
                       gint num_messages,
                       gint flags,
                       GCancellable *cancellable,
                       GError **error);

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().

If address is NULL then the message is sent to the default receiver (set by g_socket_connect()).

vectors must point to an array of GOutputVector structs and num_vectors must be the length of this array. (If num_vectors is -1, then vectors is assumed to be terminated by a GOutputVector with a NULL buffer pointer.) The GOutputVector structs describe the buffers that the sent data will be gathered from. Using multiple GOutputVectors is more memory-efficient than manually copying data from multiple sources into a single buffer, and more network-efficient than making multiple calls to g_socket_send().

messages , if non-NULL, is taken to point to an array of num_messages GSocketControlMessage instances. These correspond to the control messages to be sent on the socket. If num_messages is -1 then messages is treated as a NULL-terminated array.

flags modify how the message is sent. The commonly available arguments for this are available in the GSocketMsgFlags enum, but the values there are the same as the system values, and the flags are passed in as-is, so you can pass in system-specific flags too.

If the socket is in blocking mode the call will block until there is space for the data in the socket queue. If there is no space available and the socket is in non-blocking mode a G_IO_ERROR_WOULD_BLOCK error will be returned. To be notified when space is available, wait for the G_IO_OUT condition. Note though that you may still receive G_IO_ERROR_WOULD_BLOCK from g_socket_send() even if you were previously notified of a G_IO_OUT condition. (On Windows in particular, this is very common due to the way the underlying APIs work.)

On error -1 is returned and error is set accordingly.

Parameters

socket

a GSocket

 

address

a GSocketAddress, or NULL.

[nullable]

vectors

an array of GOutputVector structs.

[array length=num_vectors]

num_vectors

the number of elements in vectors , or -1

 

messages

a pointer to an array of GSocketControlMessages, or NULL.

[array length=num_messages][nullable]

num_messages

number of elements in messages , or -1.

 

flags

an int containing GSocketMsgFlags flags

 

cancellable

a GCancellable or NULL.

[nullable]

error

GError for error reporting, or NULL to ignore.

 

Returns

Number of bytes written (which may be less than size ), or -1 on error

Since: 2.22


g_socket_send_messages ()

gint
g_socket_send_messages (GSocket *socket,
                        GOutputMessage *messages,
                        guint num_messages,
                        gint flags,
                        GCancellable *cancellable,
                        GError **error);

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().

messages must point to an array of GOutputMessage structs and num_messages must be the length of this array. Each GOutputMessage contains an address to send the data to, and a pointer to an array of GOutputVector structs to describe the buffers that the data to be sent for each message will be gathered from. Using multiple GOutputVectors is more memory-efficient than manually copying data from multiple sources into a single buffer, and more network-efficient than making multiple calls to g_socket_send(). Sending multiple messages in one go avoids the overhead of making a lot of syscalls in scenarios where a lot of data packets need to be sent (e.g. high-bandwidth video streaming over RTP/UDP), or where the same data needs to be sent to multiple recipients.

flags modify how the message is sent. The commonly available arguments for this are available in the GSocketMsgFlags enum, but the values there are the same as the system values, and the flags are passed in as-is, so you can pass in system-specific flags too.

If the socket is in blocking mode the call will block until there is space for all the data in the socket queue. If there is no space available and the socket is in non-blocking mode a G_IO_ERROR_WOULD_BLOCK error will be returned if no data was written at all, otherwise the number of messages sent will be returned. To be notified when space is available, wait for the G_IO_OUT condition. Note though that you may still receive G_IO_ERROR_WOULD_BLOCK from g_socket_send() even if you were previously notified of a G_IO_OUT condition. (On Windows in particular, this is very common due to the way the underlying APIs work.)

On error -1 is returned and error is set accordingly. An error will only be returned if zero messages could be sent; otherwise the number of messages successfully sent before the error will be returned.

Parameters

socket

a GSocket

 

messages

an array of GOutputMessage structs.

[array length=num_messages]

num_messages

the number of elements in messages

 

flags

an int containing GSocketMsgFlags flags

 

cancellable

a GCancellable or NULL.

[nullable]

error

GError for error reporting, or NULL to ignore.

 

Returns

number of messages sent, or -1 on error. Note that the number of messages sent may be smaller than num_messages if the socket is non-blocking or if num_messages was larger than UIO_MAXIOV (1024), in which case the caller may re-try to send the remaining messages.

Since: 2.44


g_socket_send_with_blocking ()

gssize
g_socket_send_with_blocking (GSocket *socket,
                             const gchar *buffer,
                             gsize size,
                             gboolean blocking,
                             GCancellable *cancellable,
                             GError **error);

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.

Parameters

socket

a GSocket

 

buffer

the buffer containing the data to send.

[array length=size][element-type guint8]

size

the number of bytes to send

 

blocking

whether to do blocking or non-blocking I/O

 

cancellable

a GCancellable or NULL.

[nullable]

error

GError for error reporting, or NULL to ignore.

 

Returns

Number of bytes written (which may be less than size ), or -1 on error

Since: 2.26


g_socket_close ()

gboolean
g_socket_close (GSocket *socket,
                GError **error);

Closes the socket, shutting down any active connection.

Closing a socket does not wait for all outstanding I/O operations to finish, so the caller should not rely on them to be guaranteed to complete even if the close returns with no error.

Once the socket is closed, all other operations will return G_IO_ERROR_CLOSED. Closing a socket multiple times will not return an error.

Sockets will be automatically closed when the last reference is dropped, but you might want to call this function to make sure resources are released as early as possible.

Beware that due to the way that TCP works, it is possible for recently-sent data to be lost if either you close a socket while the G_IO_IN condition is set, or else if the remote connection tries to send something to you after you close the socket but before it has finished reading all of the data you sent. There is no easy generic way to avoid this problem; the easiest fix is to design the network protocol such that the client will never send data "out of turn". Another solution is for the server to half-close the connection by calling g_socket_shutdown() with only the shutdown_write flag set, and then wait for the client to notice this and close its side of the connection, after which the server can safely call g_socket_close(). (This is what GTcpConnection does if you call g_tcp_connection_set_graceful_disconnect(). But of course, this only works if the client will close its connection after the server does.)

Parameters

socket

a GSocket

 

error

GError for error reporting, or NULL to ignore.

 

Returns

TRUE on success, FALSE on error

Since: 2.22


g_socket_is_closed ()

gboolean
g_socket_is_closed (GSocket *socket);

Checks whether a socket is closed.

Parameters

socket

a GSocket

 

Returns

TRUE if socket is closed, FALSE otherwise

Since: 2.22


g_socket_shutdown ()

gboolean
g_socket_shutdown (GSocket *socket,
                   gboolean shutdown_read,
                   gboolean shutdown_write,
                   GError **error);

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

If shutdown_read is TRUE then the receiving side of the connection is shut down, and further reading is disallowed.

If shutdown_write is TRUE then the sending side of the connection is shut down, and further writing is disallowed.

It is allowed for both shutdown_read and shutdown_write to be TRUE.

One example where it is useful to shut down only one side of a connection is graceful disconnect for TCP connections where you close the sending side, then wait for the other side to close the connection, thus ensuring that the other side saw all sent data.

Parameters

socket

a GSocket

 

shutdown_read

whether to shut down the read side

 

shutdown_write

whether to shut down the write side

 

error

GError for error reporting, or NULL to ignore.

 

Returns

TRUE on success, FALSE on error

Since: 2.22


g_socket_is_connected ()

gboolean
g_socket_is_connected (GSocket *socket);

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

If using g_socket_shutdown(), this function will return TRUE until the socket has been shut down for reading and writing. If you do a non-blocking connect, this function will not return TRUE until after you call g_socket_check_connect_result().

Parameters

socket

a GSocket.

 

Returns

TRUE if socket is connected, FALSE otherwise.

Since: 2.22


g_socket_create_source ()

GSource *
g_socket_create_source (GSocket *socket,
                        GIOCondition condition,
                        GCancellable *cancellable);

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 .

The callback on the source is of the GSocketSourceFunc type.

It is meaningless to specify G_IO_ERR or G_IO_HUP in condition ; these conditions will always be reported output if they are true.

cancellable if not NULL can be used to cancel the source, which will cause the source to trigger, reporting the current condition (which is likely 0 unless cancellation happened at the same time as a condition change). You can check for this in the callback using g_cancellable_is_cancelled().

If socket has a timeout set, and it is reached before condition occurs, the source will then trigger anyway, reporting G_IO_IN or G_IO_OUT depending on condition . However, socket will have been marked as having had a timeout, and so the next GSocket I/O method you call will then fail with a G_IO_ERROR_TIMED_OUT.

[skip]

Parameters

socket

a GSocket

 

condition

a GIOCondition mask to monitor

 

cancellable

a GCancellable or NULL.

[nullable]

Returns

a newly allocated GSource, free with g_source_unref().

[transfer full]

Since: 2.22


g_socket_condition_check ()

GIOCondition
g_socket_condition_check (GSocket *socket,
                          GIOCondition condition);

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.

Note that on Windows, it is possible for an operation to return G_IO_ERROR_WOULD_BLOCK even immediately after g_socket_condition_check() has claimed that the socket is ready for writing. Rather than calling g_socket_condition_check() and then writing to the socket if it succeeds, it is generally better to simply try writing to the socket right away, and try again later if the initial attempt returns G_IO_ERROR_WOULD_BLOCK.

It is meaningless to specify G_IO_ERR or G_IO_HUP in condition; these conditions will always be set in the output if they are true.

This call never blocks.

Parameters

socket

a GSocket

 

condition

a GIOCondition mask to check

 

Returns

the GIOCondition mask of the current state

Since: 2.22


g_socket_condition_wait ()

gboolean
g_socket_condition_wait (GSocket *socket,
                         GIOCondition condition,
                         GCancellable *cancellable,
                         GError **error);

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

If cancellable is cancelled before the condition is met, or if the socket has a timeout set and it is reached before the condition is met, then FALSE is returned and error , if non-NULL, is set to the appropriate value (G_IO_ERROR_CANCELLED or G_IO_ERROR_TIMED_OUT).

See also g_socket_condition_timed_wait().

Parameters

socket

a GSocket

 

condition

a GIOCondition mask to wait for

 

cancellable

a GCancellable, or NULL.

[nullable]

error

a GError pointer, or NULL

 

Returns

TRUE if the condition was met, FALSE otherwise

Since: 2.22


g_socket_condition_timed_wait ()

gboolean
g_socket_condition_timed_wait (GSocket *socket,
                               GIOCondition condition,
                               gint64 timeout,
                               GCancellable *cancellable,
                               GError **error);

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

If cancellable is cancelled before the condition is met, or if timeout (or the socket's “timeout”) is reached before the condition is met, then FALSE is returned and error , if non-NULL, is set to the appropriate value (G_IO_ERROR_CANCELLED or G_IO_ERROR_TIMED_OUT).

If you don't want a timeout, use g_socket_condition_wait(). (Alternatively, you can pass -1 for timeout .)

Note that although timeout is in microseconds for consistency with other GLib APIs, this function actually only has millisecond resolution, and the behavior is undefined if timeout is not an exact number of milliseconds.

Parameters

socket

a GSocket

 

condition

a GIOCondition mask to wait for

 

timeout

the maximum time (in microseconds) to wait, or -1

 

cancellable

a GCancellable, or NULL.

[nullable]

error

a GError pointer, or NULL

 

Returns

TRUE if the condition was met, FALSE otherwise

Since: 2.32


g_socket_get_available_bytes ()

gssize
g_socket_get_available_bytes (GSocket *socket);

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

If socket is a UDP or SCTP socket, this will return the size of just the next packet, even if additional packets are buffered after that one.

Note that on Windows, this function is rather inefficient in the UDP case, and so if you know any plausible upper bound on the size of the incoming packet, it is better to just do a g_socket_receive() with a buffer of that size, rather than calling g_socket_get_available_bytes() first and then doing a receive of exactly the right size.

Parameters

socket

a GSocket

 

Returns

the number of bytes that can be read from the socket without blocking or truncating, or -1 on error.

Since: 2.32


g_socket_set_listen_backlog ()

void
g_socket_set_listen_backlog (GSocket *socket,
                             gint 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.

Note that this must be called before g_socket_listen() and has no effect if called after that.

Parameters

socket

a GSocket.

 

backlog

the maximum number of pending connections.

 

Since: 2.22


g_socket_get_listen_backlog ()

gint
g_socket_get_listen_backlog (GSocket *socket);

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

Parameters

socket

a GSocket.

 

Returns

the maximum number of pending connections.

Since: 2.22


g_socket_get_blocking ()

gboolean
g_socket_get_blocking (GSocket *socket);

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

Parameters

socket

a GSocket.

 

Returns

TRUE if blocking I/O is used, FALSE otherwise.

Since: 2.22


g_socket_set_blocking ()

void
g_socket_set_blocking (GSocket *socket,
                       gboolean 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.

All sockets are created in blocking mode. However, note that the platform level socket is always non-blocking, and blocking mode is a GSocket level feature.

Parameters

socket

a GSocket.

 

blocking

Whether to use blocking I/O or not.

 

Since: 2.22


g_socket_get_keepalive ()

gboolean
g_socket_get_keepalive (GSocket *socket);

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

Parameters

socket

a GSocket.

 

Returns

TRUE if keepalive is active, FALSE otherwise.

Since: 2.22


g_socket_set_keepalive ()

void
g_socket_set_keepalive (GSocket *socket,
                        gboolean 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.

This option is only functional on certain kinds of sockets. (Notably, G_SOCKET_PROTOCOL_TCP sockets.)

The exact time between pings is system- and protocol-dependent, but will normally be at least two hours. Most commonly, you would set this flag on a server socket if you want to allow clients to remain idle for long periods of time, but also want to ensure that connections are eventually garbage-collected if clients crash or become unreachable.

Parameters

socket

a GSocket.

 

keepalive

Value for the keepalive flag

 

Since: 2.22


g_socket_get_timeout ()

guint
g_socket_get_timeout (GSocket *socket);

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

Parameters

socket

a GSocket.

 

Returns

the timeout in seconds

Since: 2.26


g_socket_set_timeout ()

void
g_socket_set_timeout (GSocket *socket,
                      guint timeout);

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

On a blocking socket, this means that any blocking GSocket operation will time out after timeout seconds of inactivity, returning G_IO_ERROR_TIMED_OUT.

On a non-blocking socket, calls to g_socket_condition_wait() will also fail with G_IO_ERROR_TIMED_OUT after the given time. Sources created with g_socket_create_source() will trigger after timeout seconds of inactivity, with the requested condition set, at which point calling g_socket_receive(), g_socket_send(), g_socket_check_connect_result(), etc, will fail with G_IO_ERROR_TIMED_OUT.

If timeout is 0 (the default), operations will never time out on their own.

Note that if an I/O operation is interrupted by a signal, this may cause the timeout to be reset.

Parameters

socket

a GSocket.

 

timeout

the timeout for socket , in seconds, or 0 for none

 

Since: 2.26


g_socket_set_ttl ()

void
g_socket_set_ttl (GSocket *socket,
                  guint ttl);

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

Parameters

socket

a GSocket.

 

ttl

the time-to-live value for all unicast packets on socket

 

Since: 2.32


g_socket_get_ttl ()

guint
g_socket_get_ttl (GSocket *socket);

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

Parameters

socket

a GSocket.

 

Returns

the time-to-live setting on socket

Since: 2.32


g_socket_get_broadcast ()

gboolean
g_socket_get_broadcast (GSocket *socket);

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

Parameters

socket

a GSocket.

 

Returns

the broadcast setting on socket

Since: 2.32


g_socket_set_broadcast ()

void
g_socket_set_broadcast (GSocket *socket,
                        gboolean broadcast);

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

Parameters

socket

a GSocket.

 

broadcast

whether socket should allow sending to broadcast addresses

 

Since: 2.32


g_socket_get_option ()

gboolean
g_socket_get_option (GSocket *socket,
                     gint level,
                     gint optname,
                     gint *value,
                     GError **error);

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.)

The <gio/gnetworking.h> header pulls in system headers that will define most of the standard/portable socket options. For unusual socket protocols or platform-dependent options, you may need to include additional headers.

Note that even for socket options that are a single byte in size, value is still a pointer to a gint variable, not a guchar; g_socket_get_option() will handle the conversion internally.

Parameters

socket

a GSocket

 

level

the "API level" of the option (eg, SOL_SOCKET)

 

optname

the "name" of the option (eg, SO_BROADCAST)

 

value

return location for the option value.

[out]

error

GError for error reporting, or NULL to ignore.

 

Returns

success or failure. On failure, error will be set, and the system error value (errno or WSAGetLastError()) will still be set to the result of the getsockopt() call.

Since: 2.36


g_socket_set_option ()

gboolean
g_socket_set_option (GSocket *socket,
                     gint level,
                     gint optname,
                     gint value,
                     GError **error);

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.)

The <gio/gnetworking.h> header pulls in system headers that will define most of the standard/portable socket options. For unusual socket protocols or platform-dependent options, you may need to include additional headers.

Parameters

socket

a GSocket

 

level

the "API level" of the option (eg, SOL_SOCKET)

 

optname

the "name" of the option (eg, SO_BROADCAST)

 

value

the value to set the option to

 

error

GError for error reporting, or NULL to ignore.

 

Returns

success or failure. On failure, error will be set, and the system error value (errno or WSAGetLastError()) will still be set to the result of the setsockopt() call.

Since: 2.36


g_socket_get_family ()

GSocketFamily
g_socket_get_family (GSocket *socket);

Gets the socket family of the socket.

Parameters

socket

a GSocket.

 

Returns

a GSocketFamily

Since: 2.22


g_socket_get_fd ()

int
g_socket_get_fd (GSocket *socket);

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.

Parameters

socket

a GSocket.

 

Returns

the file descriptor of the socket.

Since: 2.22


g_socket_get_local_address ()

GSocketAddress *
g_socket_get_local_address (GSocket *socket,
                            GError **error);

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.

Parameters

socket

a GSocket.

 

error

GError for error reporting, or NULL to ignore.

 

Returns

a GSocketAddress or NULL on error. Free the returned object with g_object_unref().

[transfer full]

Since: 2.22


g_socket_get_protocol ()

GSocketProtocol
g_socket_get_protocol (GSocket *socket);

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

Parameters

socket

a GSocket.

 

Returns

a protocol id, or -1 if unknown

Since: 2.22


g_socket_get_remote_address ()

GSocketAddress *
g_socket_get_remote_address (GSocket *socket,
                             GError **error);

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

Parameters

socket

a GSocket.

 

error

GError for error reporting, or NULL to ignore.

 

Returns

a GSocketAddress or NULL on error. Free the returned object with g_object_unref().

[transfer full]

Since: 2.22


g_socket_get_socket_type ()

GSocketType
g_socket_get_socket_type (GSocket *socket);

Gets the socket type of the socket.

Parameters

socket

a GSocket.

 

Returns

a GSocketType

Since: 2.22


g_socket_speaks_ipv4 ()

gboolean
g_socket_speaks_ipv4 (GSocket *socket);

Checks if a socket is capable of speaking IPv4.

IPv4 sockets are capable of speaking IPv4. On some operating systems and under some combinations of circumstances IPv6 sockets are also capable of speaking IPv4. See RFC 3493 section 3.7 for more information.

No other types of sockets are currently considered as being capable of speaking IPv4.

Parameters

socket

a GSocket

 

Returns

TRUE if this socket can be used with IPv4.

Since: 2.22


g_socket_get_credentials ()

GCredentials *
g_socket_get_credentials (GSocket *socket,
                          GError **error);

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).

If this operation isn't supported on the OS, the method fails with the G_IO_ERROR_NOT_SUPPORTED error. On Linux this is implemented by reading the SO_PEERCRED option on the underlying socket.

Other ways to obtain credentials from a foreign peer includes the GUnixCredentialsMessage type and g_unix_connection_send_credentials() / g_unix_connection_receive_credentials() functions.

Parameters

socket

a GSocket.

 

error

GError for error reporting, or NULL to ignore.

 

Returns

NULL if error is set, otherwise a GCredentials object that must be freed with g_object_unref().

[transfer full]

Since: 2.26


g_socket_join_multicast_group ()

gboolean
g_socket_join_multicast_group (GSocket *socket,
                               GInetAddress *group,
                               gboolean source_specific,
                               const gchar *iface,
                               GError **error);

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().

If iface is NULL, the system will automatically pick an interface to bind to based on group .

If source_specific is TRUE, source-specific multicast as defined in RFC 4604 is used. Note that on older platforms this may fail with a G_IO_ERROR_NOT_SUPPORTED error.

Parameters

socket

a GSocket.

 

group

a GInetAddress specifying the group address to join.

 

iface

Name of the interface to use, or NULL.

[nullable]

source_specific

TRUE if source-specific multicast should be used

 

error

GError for error reporting, or NULL to ignore.

 

Returns

TRUE on success, FALSE on error.

Since: 2.32


g_socket_leave_multicast_group ()

gboolean
g_socket_leave_multicast_group (GSocket *socket,
                                GInetAddress *group,
                                gboolean source_specific,
                                const gchar *iface,
                                GError **error);

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).

socket remains bound to its address and port, and can still receive unicast messages after calling this.

Parameters

socket

a GSocket.

 

group

a GInetAddress specifying the group address to leave.

 

iface

Interface used.

[nullable]

source_specific

TRUE if source-specific multicast was used

 

error

GError for error reporting, or NULL to ignore.

 

Returns

TRUE on success, FALSE on error.

Since: 2.32


g_socket_get_multicast_loopback ()

gboolean
g_socket_get_multicast_loopback (GSocket *socket);

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.

Parameters

socket

a GSocket.

 

Returns

the multicast loopback setting on socket

Since: 2.32


g_socket_set_multicast_loopback ()

void
g_socket_set_multicast_loopback (GSocket *socket,
                                 gboolean 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.

Parameters

socket

a GSocket.

 

loopback

whether socket should receive messages sent to its multicast groups from the local host

 

Since: 2.32


g_socket_get_multicast_ttl ()

guint
g_socket_get_multicast_ttl (GSocket *socket);

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

Parameters

socket

a GSocket.

 

Returns

the multicast time-to-live setting on socket

Since: 2.32


g_socket_set_multicast_ttl ()

void
g_socket_set_multicast_ttl (GSocket *socket,
                            guint 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.

Parameters

socket

a GSocket.

 

ttl

the time-to-live value for all multicast datagrams on socket

 

Since: 2.32

Types and Values

GSocket

typedef struct _GSocket GSocket;

A lowlevel network socket object.

Since: 2.22


enum GSocketType

Flags used when creating a GSocket. Some protocols may not implement all the socket types.

Members

G_SOCKET_TYPE_INVALID

Type unknown or wrong

 

G_SOCKET_TYPE_STREAM

Reliable connection-based byte streams (e.g. TCP).

 

G_SOCKET_TYPE_DATAGRAM

Connectionless, unreliable datagram passing. (e.g. UDP)

 

G_SOCKET_TYPE_SEQPACKET

Reliable connection-based passing of datagrams of fixed maximum length (e.g. SCTP).

 

Since: 2.22


enum GSocketProtocol

A protocol identifier is specified when creating a GSocket, which is a family/type specific identifier, where 0 means the default protocol for the particular family/type.

This enum contains a set of commonly available and used protocols. You can also pass any other identifiers handled by the platform in order to use protocols not listed here.

Members

G_SOCKET_PROTOCOL_UNKNOWN

The protocol type is unknown

 

G_SOCKET_PROTOCOL_DEFAULT

The default protocol for the family/type

 

G_SOCKET_PROTOCOL_TCP

TCP over IP

 

G_SOCKET_PROTOCOL_UDP

UDP over IP

 

G_SOCKET_PROTOCOL_SCTP

SCTP over IP

 

Since: 2.22


enum GSocketMsgFlags

Flags used in g_socket_receive_message() and g_socket_send_message(). The flags listed in the enum are some commonly available flags, but the values used for them are the same as on the platform, and any other flags are passed in/out as is. So to use a platform specific flag, just include the right system header and pass in the flag.

Members

G_SOCKET_MSG_NONE

No flags.

 

G_SOCKET_MSG_OOB

Request to send/receive out of band data.

 

G_SOCKET_MSG_PEEK

Read data from the socket without removing it from the queue.

 

G_SOCKET_MSG_DONTROUTE

Don't use a gateway to send out the packet, only send to hosts on directly connected networks.

 

Since: 2.22


struct GInputVector

struct GInputVector {
  gpointer buffer;
  gsize size;
};

Structure used for scatter/gather data input. You generally pass in an array of GInputVectors and the operation will store the read data starting in the first buffer, switching to the next as needed.

Members

gpointer buffer;

Pointer to a buffer where data will be written.

 

gsize size;

the available size in buffer .

 

Since: 2.22


struct GInputMessage

struct GInputMessage {
  GSocketAddress         **address;

  GInputVector            *vectors;
  guint                    num_vectors;

  gsize                    bytes_received;
  gint                     flags;

  GSocketControlMessage ***control_messages;
  guint                   *num_control_messages;
};

Structure used for scatter/gather data input when receiving multiple messages or packets in one go. You generally pass in an array of empty GInputVectors and the operation will use all the buffers as if they were one buffer, and will set bytes_received to the total number of bytes received across all GInputVectors.

This structure closely mirrors struct mmsghdr and struct msghdr from the POSIX sockets API (see man 2 recvmmsg).

If address is non-NULL then it is set to the source address the message was received from, and the caller must free it afterwards.

If control_messages is non-NULL then it is set to an array of control messages received with the message (if any), and the caller must free it afterwards. num_control_messages is set to the number of elements in this array, which may be zero.

Flags relevant to this message will be returned in flags . For example, MSG_EOR or MSG_TRUNC.

Members

GSocketAddress **address;

return location for a GSocketAddress, or NULL.

[optional][out][transfer full]

GInputVector *vectors;

pointer to an array of input vectors.

[array length=num_vectors][out]

guint num_vectors;

the number of input vectors pointed to by vectors

 

gsize bytes_received;

will be set to the number of bytes that have been received.

[out]

gint flags;

collection of GSocketMsgFlags for the received message, outputted by the call.

[out]

GSocketControlMessage ***control_messages;

(array length=num_control_messages) (optional) (out) (transfer full): return location for a caller-allocated array of GSocketControlMessages, or NULL

 

guint *num_control_messages;

return location for the number of elements in control_messages .

[out][optional]

Since: 2.48


struct GOutputVector

struct GOutputVector {
  gconstpointer buffer;
  gsize size;
};

Structure used for scatter/gather data output. You generally pass in an array of GOutputVectors and the operation will use all the buffers as if they were one buffer.

Members

gconstpointer buffer;

Pointer to a buffer of data to read.

 

gsize size;

the size of buffer .

 

Since: 2.22


struct GOutputMessage

struct GOutputMessage {
  GSocketAddress         *address;

  GOutputVector          *vectors;
  guint                   num_vectors;

  guint                   bytes_sent;

  GSocketControlMessage **control_messages;
  guint                   num_control_messages;
};

Structure used for scatter/gather data output when sending multiple messages or packets in one go. You generally pass in an array of GOutputVectors and the operation will use all the buffers as if they were one buffer.

If address is NULL then the message is sent to the default receiver (as previously set by g_socket_connect()).

Members

GSocketAddress *address;

a GSocketAddress, or NULL.

[nullable]

GOutputVector *vectors;

pointer to an array of output vectors

 

guint num_vectors;

the number of output vectors pointed to by vectors .

 

guint bytes_sent;

initialize to 0. Will be set to the number of bytes that have been sent

 

GSocketControlMessage **control_messages;

a pointer to an array of GSocketControlMessages, or NULL.

[array length=num_control_messages][nullable]

guint num_control_messages;

number of elements in control_messages .

 

Since: 2.44

Property Details

The “blocking” property

  “blocking”                 gboolean

Whether or not I/O on this socket is blocking.

Flags: Read / Write

Default value: TRUE


The “broadcast” property

  “broadcast”                gboolean

Whether the socket should allow sending to broadcast addresses.

Flags: Read / Write

Default value: FALSE

Since: 2.32


The “family” property

  “family”                   GSocketFamily

The sockets address family.

Flags: Read / Write / Construct Only

Default value: G_SOCKET_FAMILY_INVALID


The “fd” property

  “fd”                       gint

The sockets file descriptor.

Flags: Read / Write / Construct Only

Default value: -1


The “keepalive” property

  “keepalive”                gboolean

Keep connection alive by sending periodic pings.

Flags: Read / Write

Default value: FALSE


The “listen-backlog” property

  “listen-backlog”           gint

Outstanding connections in the listen queue.

Flags: Read / Write

Allowed values: [0,128]

Default value: 10


The “local-address” property

  “local-address”            GSocketAddress *

The local address the socket is bound to.

Flags: Read


The “multicast-loopback” property

  “multicast-loopback”       gboolean

Whether outgoing multicast packets loop back to the local host.

Flags: Read / Write

Default value: TRUE

Since: 2.32


The “multicast-ttl” property

  “multicast-ttl”            guint

Time-to-live out outgoing multicast packets

Flags: Read / Write

Default value: 1

Since: 2.32


The “protocol” property

  “protocol”                 GSocketProtocol

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

Flags: Read / Write / Construct Only

Default value: G_SOCKET_PROTOCOL_UNKNOWN


The “remote-address” property

  “remote-address”           GSocketAddress *

The remote address the socket is connected to.

Flags: Read


The “timeout” property

  “timeout”                  guint

The timeout in seconds on socket I/O

Flags: Read / Write

Default value: 0

Since: 2.26


The “ttl” property

  “ttl”                      guint

Time-to-live for outgoing unicast packets

Flags: Read / Write

Default value: 0

Since: 2.32


The “type” property

  “type”                     GSocketType

The sockets type.

Flags: Read / Write / Construct Only

Default value: G_SOCKET_TYPE_STREAM

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