Gio.Socket¶

class — extends GObject.Object, DatagramBased, Initable

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 SocketClient, SocketService and SocketConnection. However there may be cases where direct use of GSocket is useful.

GSocket implements the Initable interface, so if it is manually constructed by e.g. GObject.Object.new you must call Initable.init and check the results before using the object. This is done automatically in Socket.new and 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 Socket.condition_check, or Socket.condition_wait. You can also use Socket.create_source and attach it to a GLib.MainContext 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 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
  }

Constructors¶

new¶

@classmethod
def new(cls, family: SocketFamily | int, type: SocketType | int, protocol: SocketProtocol | int) -> Socket

Creates a new Socket with the defined family, type and protocol. If protocol is 0 (SocketProtocol.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. SocketProtocol 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 SocketProtocol if you know the protocol number used for it.

Parameters:

family — the socket family to use, e.g. SocketFamily.IPV4.
type — the socket type to use.
protocol — the id of the protocol to use, or 0 for default.

new_from_fd¶

@classmethod
def new_from_fd(cls, fd: int) -> Socket

Creates a new Socket 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 Socket.

On success, the returned Socket 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 IOErrorEnum.FAILED

Parameters:

fd — a native socket file descriptor.

Methods¶

accept¶

def accept(self, cancellable: Cancellable | None = ...) -> Socket

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

The socket must be bound to a local address with Socket.bind and must be listening for incoming connections (Socket.listen).

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

Parameters:

cancellable — a GCancellable or None

bind¶

def bind(self, address: SocketAddress, allow_reuse: bool) -> bool

When a socket is created it is attached to an address family, but it doesn't have an address in this family. 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 Socket.listen and 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 Socket.accept on), and False for client sockets. (Failing to set this flag on a server socket may cause Socket.bind to return IOErrorEnum.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:

address — a SocketAddress specifying the local address.
allow_reuse — whether to allow reusing this address

check_connect_result¶

def check_connect_result(self) -> bool

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

close¶

def close(self) -> bool

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 IOErrorEnum.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 GObject.IOCondition.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 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 Socket.close. (This is what TcpConnection does if you call TcpConnection.set_graceful_disconnect. But of course, this only works if the client will close its connection after the server does.)

condition_check¶

def condition_check(self, condition: GLib.IOCondition | int) -> GLib.IOCondition

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 IOErrorEnum.WOULD_BLOCK even immediately after Socket.condition_check has claimed that the socket is ready for writing. Rather than calling 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 IOErrorEnum.WOULD_BLOCK.

It is meaningless to specify GObject.IOCondition.ERR or GObject.IOCondition.HUP in condition; these conditions will always be set in the output if they are true.

This call never blocks.

Parameters:

condition — a GObject.IOCondition mask to check

condition_timed_wait¶

def condition_timed_wait(self, condition: GLib.IOCondition | int, timeout_us: int, cancellable: Cancellable | None = ...) -> bool

Waits for up to timeout_us 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_us (or the socket's Socket:timeout) is reached before the condition is met, then False is returned and error, if non-None, is set to the appropriate value (IOErrorEnum.CANCELLED or IOErrorEnum.TIMED_OUT).

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

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

Parameters:

condition — a GObject.IOCondition mask to wait for
timeout_us — the maximum time (in microseconds) to wait, or -1
cancellable — a Cancellable, or None

condition_wait¶

def condition_wait(self, condition: GLib.IOCondition | int, cancellable: Cancellable | None = ...) -> bool

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-None, is set to the appropriate value (IOErrorEnum.CANCELLED or IOErrorEnum.TIMED_OUT).

connect¶

def connect(self, address: SocketAddress, cancellable: Cancellable | None = ...) -> bool

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 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 IOErrorEnum.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 Socket.check_connect_result.

Parameters:

address — a SocketAddress specifying the remote address.
cancellable — a GCancellable or None

connection_factory_create_connection¶

def connection_factory_create_connection(self) -> SocketConnection

Creates a SocketConnection subclass of the right type for socket.

get_available_bytes¶

def get_available_bytes(self) -> int

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 Socket.receive with a buffer of that size, rather than calling Socket.get_available_bytes first and then doing a receive of exactly the right size.

get_blocking¶

def get_blocking(self) -> bool

Gets the blocking mode of the socket. For details on blocking I/O, see Socket.set_blocking.

get_broadcast¶

def get_broadcast(self) -> bool

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

get_credentials¶

def get_credentials(self) -> Credentials

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

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

This method can be expected to be available on the following platforms:

Linux since GLib 2.26
OpenBSD since GLib 2.30
Solaris, Illumos and OpenSolaris since GLib 2.40
NetBSD since GLib 2.42
macOS, tvOS, iOS since GLib 2.66

Other ways to obtain credentials from a foreign peer includes the UnixCredentialsMessage type and UnixConnection.send_credentials / UnixConnection.receive_credentials functions.

get_family¶

def get_family(self) -> SocketFamily

Gets the socket family of the socket.

get_fd¶

def get_fd(self) -> int

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.

get_keepalive¶

def get_keepalive(self) -> bool

Gets the keepalive mode of the socket. For details on this, see Socket.set_keepalive.

get_listen_backlog¶

def get_listen_backlog(self) -> int

Gets the listen backlog setting of the socket. For details on this, see Socket.set_listen_backlog.

get_local_address¶

def get_local_address(self) -> SocketAddress

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.

get_multicast_loopback¶

def get_multicast_loopback(self) -> bool

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.

get_multicast_ttl¶

def get_multicast_ttl(self) -> int

Gets the multicast time-to-live setting on socket; see Socket.set_multicast_ttl for more details.

get_option¶

def get_option(self, level: int, optname: int) -> tuple[bool, int]

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; Socket.get_option will handle the conversion internally.

Parameters:

level — the "API level" of the option (eg, SOL_SOCKET)
optname — the "name" of the option (eg, SO_BROADCAST)

get_protocol¶

def get_protocol(self) -> SocketProtocol

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

get_remote_address¶

def get_remote_address(self) -> SocketAddress

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

get_socket_type¶

def get_socket_type(self) -> SocketType

Gets the socket type of the socket.

get_timeout¶

def get_timeout(self) -> int

Gets the timeout setting of the socket. For details on this, see Socket.set_timeout.

get_ttl¶

def get_ttl(self) -> int

Gets the unicast time-to-live setting on socket; see Socket.set_ttl for more details.

is_closed¶

def is_closed(self) -> bool

Checks whether a socket is closed.

is_connected¶

def is_connected(self) -> bool

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

If using 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 Socket.check_connect_result.

join_multicast_group¶

def join_multicast_group(self, group: InetAddress, source_specific: bool, iface: str | None = ...) -> bool

Registers socket to receive multicast messages sent to group. socket must be a SocketType.DATAGRAM socket, and must have been bound to an appropriate interface and port with Socket.bind.

If iface is None, 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 IOErrorEnum.NOT_SUPPORTED error.

To bind to a given source-specific multicast address, use Socket.join_multicast_group_ssm instead.

Parameters:

group — a InetAddress specifying the group address to join.
source_specific — True if source-specific multicast should be used
iface — Name of the interface to use, or None

join_multicast_group_ssm¶

def join_multicast_group_ssm(self, group: InetAddress, source_specific: InetAddress | None = ..., iface: str | None = ...) -> bool

Registers socket to receive multicast messages sent to group. socket must be a SocketType.DATAGRAM socket, and must have been bound to an appropriate interface and port with Socket.bind.

If iface is None, the system will automatically pick an interface to bind to based on group.

If source_specific is not None, use source-specific multicast as defined in RFC 4604. Note that on older platforms this may fail with a IOErrorEnum.NOT_SUPPORTED error.

Note that this function can be called multiple times for the same group with different source_specific in order to receive multicast packets from more than one source.

Parameters:

group — a InetAddress specifying the group address to join.
source_specific — a InetAddress specifying the source-specific multicast address or None to ignore.
iface — Name of the interface to use, or None

leave_multicast_group¶

def leave_multicast_group(self, group: InetAddress, source_specific: bool, iface: str | None = ...) -> bool

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.

To unbind to a given source-specific multicast address, use Socket.leave_multicast_group_ssm instead.

Parameters:

group — a InetAddress specifying the group address to leave.
source_specific — True if source-specific multicast was used
iface — Interface used

leave_multicast_group_ssm¶

def leave_multicast_group_ssm(self, group: InetAddress, source_specific: InetAddress | None = ..., iface: str | None = ...) -> bool

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:

group — a InetAddress specifying the group address to leave.
source_specific — a InetAddress specifying the source-specific multicast address or None to ignore.
iface — Name of the interface to use, or None

listen¶

def listen(self) -> bool

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

Before calling this the socket must be bound to a local address using Socket.bind.

To set the maximum amount of outstanding clients, use Socket.set_listen_backlog.

receive¶

def receive(self, cancellable: Cancellable | None = ...) -> tuple[int, list[int]]

Receive data (up to size bytes) from a socket. This is mainly used by connection-oriented sockets; it is identical to Socket.receive_from with address set to None.

For SocketType.DATAGRAM and SocketType.SEQPACKET sockets, 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 SocketType.STREAM sockets, 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 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 IOErrorEnum.WOULD_BLOCK error will be returned. To be notified when data is available, wait for the GObject.IOCondition.IN condition.

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

Parameters:

cancellable — a GCancellable or None

receive_bytes¶

def receive_bytes(self, size: int, timeout_us: int, cancellable: Cancellable | None = ...) -> bytes

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

This function is a variant of Socket.receive which returns a GLib.Bytes rather than a plain buffer.

Pass -1 to timeout_us to block indefinitely until data is received (or the connection is closed, or there is an error). Pass 0 to use the default timeout from Socket.timeout, or pass a positive number to wait for that many microseconds for data before returning G_IO_ERROR_TIMED_OUT.

Parameters:

size — the number of bytes you want to read from the socket
timeout_us — the timeout to wait for, in microseconds, or -1 to block indefinitely
cancellable — a GCancellable, or NULL

receive_bytes_from¶

def receive_bytes_from(self, size: int, timeout_us: int, cancellable: Cancellable | None = ...) -> tuple[bytes, SocketAddress]

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

This function is a variant of Socket.receive_from which returns a GLib.Bytes rather than a plain buffer.

If address is non-None then address will be set equal to the source address of the received packet.

The address is owned by the caller.

Pass -1 to timeout_us to block indefinitely until data is received (or the connection is closed, or there is an error). Pass 0 to use the default timeout from Socket.timeout, or pass a positive number to wait for that many microseconds for data before returning G_IO_ERROR_TIMED_OUT.

Parameters:

size — the number of bytes you want to read from the socket
timeout_us — the timeout to wait for, in microseconds, or -1 to block indefinitely
cancellable — a Cancellable, or NULL

receive_from¶

def receive_from(self, cancellable: Cancellable | None = ...) -> tuple[int, SocketAddress, list[int]]

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

If address is non-None then address will be set equal to the source address of the received packet. address is owned by the caller.

See Socket.receive for additional information.

Parameters:

cancellable — a GCancellable or None

receive_message¶

def receive_message(self, vectors: list[InputVector], flags: int, cancellable: Cancellable | None = ...) -> tuple[int, SocketAddress, list[SocketControlMessage], int]

Receive data from a socket. For receiving multiple messages, see Socket.receive_messages; for easier use, see Socket.receive and Socket.receive_from.

If address is non-None 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 InputVector 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 InputVector with a None buffer pointer.

As a special case, if num_vectors is 0 (in which case, vectors may of course be None), 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-None, will be set to point to a newly-allocated array of SocketControlMessage instances or None if no such messages was received. These correspond to the control messages received from the kernel, one SocketControlMessage per message from the kernel. This array is None-terminated and must be freed by the caller using GLib.free after calling GObject.Object.unref on each element. If messages is None, any control messages received will be discarded.

num_messages, if non-None, will be set to the number of control messages received.

If both messages and num_messages are non-None, then num_messages gives the number of SocketControlMessage instances in messages (ie: not including the None terminator).

flags is an in/out parameter. The commonly available arguments for this are available in the SocketMsgFlags 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 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 Socket.receive, data may be discarded if socket is SocketType.DATAGRAM or SocketType.SEQPACKET and you do not provide enough buffer space to read a complete message. You can pass SocketMsgFlags.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 IOErrorEnum.WOULD_BLOCK error will be returned. To be notified when data is available, wait for the GObject.IOCondition.IN condition.

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

Parameters:

vectors — an array of InputVector structs
flags — a pointer to an int containing SocketMsgFlags flags, which may additionally contain other platform specific flags
cancellable — a GCancellable or None

receive_messages¶

def receive_messages(self, messages: list[InputMessage], flags: int, cancellable: Cancellable | None = ...) -> int

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 Socket.receive, Socket.receive_from, and Socket.receive_message.

messages must point to an array of InputMessage structs and num_messages must be the length of this array. Each InputMessage contains a pointer to an array of InputVector 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 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 SocketMsgFlags 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 InputMessage.flags.

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

If Socket:blocking is True the call will block until num_messages have been received, or the end of the stream is reached.

If Socket:blocking is False the call will return up to num_messages without blocking, or IOErrorEnum.WOULD_BLOCK if no messages are queued in the operating system to be received.

In blocking mode, if Socket:timeout is positive and is reached before any messages are received, IOErrorEnum.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 GObject.IOCondition.IN condition. Note though that you may still receive IOErrorEnum.WOULD_BLOCK from Socket.receive_messages even if you were previously notified of a GObject.IOCondition.IN condition.

If the remote peer closes the connection, any messages queued in the operating system will be returned, and subsequent calls to 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:

messages — an array of InputMessage structs
flags — an int containing SocketMsgFlags flags for the overall operation, which may additionally contain other platform specific flags
cancellable — a GCancellable or None

receive_with_blocking¶

def receive_with_blocking(self, blocking: bool, cancellable: Cancellable | None = ...) -> tuple[int, list[int]]

This behaves exactly the same as 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:

blocking — whether to do blocking or non-blocking I/O
cancellable — a GCancellable or None

send¶

def send(self, buffer: list[int], cancellable: Cancellable | None = ...) -> int

Tries to send size bytes from buffer on the socket. This is mainly used by connection-oriented sockets; it is identical to Socket.send_to with address set to None.

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 IOErrorEnum.WOULD_BLOCK error will be returned. To be notified when space is available, wait for the GObject.IOCondition.OUT condition. Note though that you may still receive IOErrorEnum.WOULD_BLOCK from Socket.send even if you were previously notified of a GObject.IOCondition.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:

buffer — the buffer containing the data to send.
cancellable — a GCancellable or None

send_message¶

def send_message(self, address: SocketAddress | None, vectors: list[OutputVector], messages: list[SocketControlMessage] | None, flags: int, cancellable: Cancellable | None = ...) -> int

Send data to address on socket. For sending multiple messages see Socket.send_messages; for easier use, see Socket.send and Socket.send_to.

If address is None then the message is sent to the default receiver (set by Socket.connect).

vectors must point to an array of OutputVector 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 OutputVector with a None buffer pointer.) The OutputVector 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 Socket.send.

messages, if non-None, is taken to point to an array of num_messages SocketControlMessage instances. These correspond to the control messages to be sent on the socket. If num_messages is -1 then messages is treated as a None-terminated array.

flags modify how the message is sent. The commonly available arguments for this are available in the SocketMsgFlags 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 IOErrorEnum.WOULD_BLOCK error will be returned. To be notified when space is available, wait for the GObject.IOCondition.OUT condition. Note though that you may still receive IOErrorEnum.WOULD_BLOCK from Socket.send even if you were previously notified of a GObject.IOCondition.OUT condition. (On Windows in particular, this is very common due to the way the underlying APIs work.)

The sum of the sizes of each OutputVector in vectors must not be greater than G_MAXSSIZE. If the message can be larger than this, then it is mandatory to use the Socket.send_message_with_timeout function.

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

Parameters:

address — a SocketAddress, or None
vectors — an array of OutputVector structs
messages — a pointer to an array of GSocketControlMessages, or None.
flags — an int containing SocketMsgFlags flags, which may additionally contain other platform specific flags
cancellable — a GCancellable or None

send_message_with_timeout¶

def send_message_with_timeout(self, address: SocketAddress | None, vectors: list[OutputVector], messages: list[SocketControlMessage] | None, flags: int, timeout_us: int, cancellable: Cancellable | None = ...) -> tuple[PollableReturn, int]

This behaves exactly the same as Socket.send_message, except that the choice of timeout behavior is determined by the timeout_us argument rather than by socket's properties.

On error PollableReturn.FAILED is returned and error is set accordingly, or if the socket is currently not writable PollableReturn.WOULD_BLOCK is returned. bytes_written will contain 0 in both cases.

Parameters:

address — a SocketAddress, or None
vectors — an array of OutputVector structs
messages — a pointer to an array of GSocketControlMessages, or None.
flags — an int containing SocketMsgFlags flags, which may additionally contain other platform specific flags
timeout_us — the maximum time (in microseconds) to wait, or -1
cancellable — a GCancellable or None

send_messages¶

def send_messages(self, messages: list[OutputMessage], flags: int, cancellable: Cancellable | None = ...) -> int

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 Socket.send, Socket.send_to, and Socket.send_message.

messages must point to an array of OutputMessage structs and num_messages must be the length of this array. Each OutputMessage contains an address to send the data to, and a pointer to an array of OutputVector 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 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 SocketMsgFlags 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 IOErrorEnum.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 GObject.IOCondition.OUT condition. Note though that you may still receive IOErrorEnum.WOULD_BLOCK from Socket.send even if you were previously notified of a GObject.IOCondition.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:

messages — an array of OutputMessage structs
flags — an int containing SocketMsgFlags flags, which may additionally contain other platform specific flags
cancellable — a GCancellable or None

send_to¶

def send_to(self, address: SocketAddress | None, buffer: list[int], cancellable: Cancellable | None = ...) -> int

Tries to send size bytes from buffer to address. If address is None then the message is sent to the default receiver (set by Socket.connect).

See Socket.send for additional information.

Parameters:

address — a SocketAddress, or None
buffer — the buffer containing the data to send.
cancellable — a GCancellable or None

send_with_blocking¶

def send_with_blocking(self, buffer: list[int], blocking: bool, cancellable: Cancellable | None = ...) -> int

This behaves exactly the same as 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:

buffer — the buffer containing the data to send.
blocking — whether to do blocking or non-blocking I/O
cancellable — a GCancellable or None

set_blocking¶

def set_blocking(self, blocking: bool) -> None

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 IOErrorEnum.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:

blocking — Whether to use blocking I/O or not.

set_broadcast¶

def set_broadcast(self, broadcast: bool) -> None

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

Parameters:

broadcast — whether socket should allow sending to broadcast addresses

set_keepalive¶

def set_keepalive(self, keepalive: bool) -> None

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, SocketProtocol.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:

keepalive — Value for the keepalive flag

set_listen_backlog¶

def set_listen_backlog(self, backlog: int) -> None

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 Socket.listen and has no effect if called after that.

Parameters:

backlog — the maximum number of pending connections.

set_multicast_loopback¶

def set_multicast_loopback(self, loopback: bool) -> None

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:

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

set_multicast_ttl¶

def set_multicast_ttl(self, ttl: int) -> None

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:

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

set_option¶

def set_option(self, level: int, optname: int, value: int) -> bool

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:

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

set_timeout¶

def set_timeout(self, timeout: int) -> None

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 Socket operation will time out after timeout seconds of inactivity, returning IOErrorEnum.TIMED_OUT.

On a non-blocking socket, calls to Socket.condition_wait will also fail with IOErrorEnum.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 Socket.receive, Socket.send, Socket.check_connect_result, etc, will fail with IOErrorEnum.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:

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

set_ttl¶

def set_ttl(self, ttl: int) -> None

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

Parameters:

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

shutdown¶

def shutdown(self, shutdown_read: bool, shutdown_write: bool) -> bool

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:

shutdown_read — whether to shut down the read side
shutdown_write — whether to shut down the write side

speaks_ipv4¶

def speaks_ipv4(self) -> bool

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.

Properties¶

blocking¶

blocking: bool  # read/write

Whether I/O on this socket is blocking.

broadcast¶

broadcast: bool  # read/write

Whether the socket should allow sending to broadcast addresses.

family¶

family: SocketFamily | int  # read/write

The socket’s address family.

fd¶

fd: int  # read/write

The socket’s file descriptor.

keepalive¶

keepalive: bool  # read/write

Whether to keep the connection alive by sending periodic pings.

listen_backlog¶

listen_backlog: int  # read/write

The number of outstanding connections in the listen queue.

local_address¶

local_address: SocketAddress  # read-only

The local address the socket is bound to.

multicast_loopback¶

multicast_loopback: bool  # read/write

Whether outgoing multicast packets loop back to the local host.

multicast_ttl¶

multicast_ttl: int  # read/write

Time-to-live out outgoing multicast packets

protocol¶

protocol: SocketProtocol | int  # read/write

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

remote_address¶

remote_address: SocketAddress  # read-only

The remote address the socket is connected to.

timeout¶

timeout: int  # read/write

The timeout in seconds on socket I/O

ttl¶

ttl: int  # read/write

Time-to-live for outgoing unicast packets

type¶

type: SocketType | int  # read/write

The socket’s type.