Socket

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.

class Socket : ObjectG, DatagramBasedIF, InitableIF {}

Constructors

this
this(GSocket* gSocket, bool ownedRef = false)

Sets our main struct and passes it to the parent class.

this
this(GSocketFamily family, GSocketType type, GSocketProtocol protocol)

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.

this
this(int fd)

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

Members

Functions

accept
Socket accept(Cancellable cancellable)

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.

bind
bool bind(SocketAddress address, bool allowReuse)

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.

checkConnectResult
bool checkConnectResult()

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.

close
bool close()

Closes the socket, shutting down any active connection.

conditionCheck
GIOCondition conditionCheck(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.

conditionTimedWait
bool conditionTimedWait(GIOCondition condition, long timeoutUs, Cancellable cancellable)

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

conditionWait
bool conditionWait(GIOCondition condition, Cancellable cancellable)

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

connect
bool connect(SocketAddress address, Cancellable cancellable)

Connect the socket to the specified remote address.

connectionFactoryCreateConnection
SocketConnection connectionFactoryCreateConnection()

Creates a GSocketConnection subclass of the right type for socket.

createSource
Source createSource(GIOCondition condition, Cancellable 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.

getAvailableBytes
ptrdiff_t getAvailableBytes()

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

getBlocking
bool getBlocking()

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

getBroadcast
bool getBroadcast()

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

getCredentials
Credentials getCredentials()

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).

getFamily
GSocketFamily getFamily()

Gets the socket family of the socket.

getFd
int getFd()

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.

getKeepalive
bool getKeepalive()

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

getListenBacklog
int getListenBacklog()

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

getLocalAddress
SocketAddress getLocalAddress()

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.

getMulticastLoopback
bool getMulticastLoopback()

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.

getMulticastTtl
uint getMulticastTtl()

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

getOption
bool getOption(int level, int optname, out int value)

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.)

getProtocol
GSocketProtocol getProtocol()

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

getRemoteAddress
SocketAddress getRemoteAddress()

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

getSocketStruct
GSocket* getSocketStruct(bool transferOwnership = false)

Get the main Gtk struct

getSocketType
GSocketType getSocketType()

Gets the socket type of the socket.

getStruct
void* getStruct()

the main Gtk struct as a void*

getTimeout
uint getTimeout()

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

getTtl
uint getTtl()

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

isClosed
bool isClosed()

Checks whether a socket is closed.

isConnected
bool isConnected()

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

joinMulticastGroup
bool joinMulticastGroup(InetAddress group, bool sourceSpecific, string iface)

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().

joinMulticastGroupSsm
bool joinMulticastGroupSsm(InetAddress group, InetAddress sourceSpecific, string iface)

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().

leaveMulticastGroup
bool leaveMulticastGroup(InetAddress group, bool sourceSpecific, string iface)

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).

leaveMulticastGroupSsm
bool leaveMulticastGroupSsm(InetAddress group, InetAddress sourceSpecific, string iface)

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).

listen
bool listen()

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

receive
ptrdiff_t receive(ref char[] buffer, Cancellable cancellable)

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.

receiveFrom
ptrdiff_t receiveFrom(out SocketAddress address, ref char[] buffer, Cancellable cancellable)

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

receiveMessage
ptrdiff_t receiveMessage(out SocketAddress address, GInputVector[] vectors, out SocketControlMessage[] messages, ref int flags, Cancellable cancellable)

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().

receiveMessages
int receiveMessages(GInputMessage[] messages, int flags, Cancellable cancellable)

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().

receiveWithBlocking
ptrdiff_t receiveWithBlocking(string buffer, bool blocking, Cancellable cancellable)

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.

send
ptrdiff_t send(string buffer, Cancellable cancellable)

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.

sendMessage
ptrdiff_t sendMessage(SocketAddress address, GOutputVector[] vectors, SocketControlMessage[] messages, int flags, Cancellable cancellable)

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().

sendMessageWithTimeout
GPollableReturn sendMessageWithTimeout(SocketAddress address, GOutputVector[] vectors, SocketControlMessage[] messages, int flags, long timeoutUs, out size_t bytesWritten, Cancellable cancellable)

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

sendMessages
int sendMessages(GOutputMessage[] messages, int flags, Cancellable cancellable)

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().

sendTo
ptrdiff_t sendTo(SocketAddress address, string buffer, Cancellable cancellable)

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()).

sendWithBlocking
ptrdiff_t sendWithBlocking(string buffer, bool blocking, Cancellable cancellable)

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.

setBlocking
void setBlocking(bool 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.

setBroadcast
void setBroadcast(bool broadcast)

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

setKeepalive
void setKeepalive(bool 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.

setListenBacklog
void setListenBacklog(int 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.

setMulticastLoopback
void setMulticastLoopback(bool 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.

setMulticastTtl
void setMulticastTtl(uint 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.

setOption
bool setOption(int level, int optname, int value)

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.)

setTimeout
void setTimeout(uint timeout)

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

setTtl
void setTtl(uint ttl)

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

shutdown
bool shutdown(bool shutdownRead, bool shutdownWrite)

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

speaksIpv4
bool speaksIpv4()

Checks if a socket is capable of speaking IPv4.

Static functions

getType
GType getType()

Variables

gSocket
GSocket* gSocket;

the main Gtk struct

Meta

Since

2.22