dsfml.network.udpsocketA module containing the UdpSocket Class.
- class UdpSocket: dsfml.network.socket.Socket;
- Specialized socket using the UDP protocol.
A UDP socket is a connectionless socket.
Instead of connecting once to a remote host, like TCP sockets, it can send to and receive from any host at any time.
It is a datagram protocol: bounded blocks of data (datagrams) are transfered over the network rather than a continuous stream of data (TCP). Therefore, one call to send will always match one call to receive (if the datagram is not lost), with the same data that was sent.
The UDP protocol is lightweight but unreliable. Unreliable means that datagrams may be duplicated, be lost or arrive reordered. However, if a datagram arrives, its data is guaranteed to be valid.
UDP is generally used for real-time communication (audio or video streaming, real-time games, etc.) where speed is crucial and lost data doesn't matter much.
Sending and receiving data can use either the low-level or the high-level functions. The low-level functions process a raw sequence of bytes, whereas the high-level interface uses packets (see sf::Packet), which are easier to use and provide more safety regarding the data that is exchanged. You can look at the sf::Packet class to get more details about how they work.
It is important to note that UdpSocket is unable to send datagrams bigger than MaxDatagramSize. In this case, it returns an error and doesn't send anything. This applies to both raw data and packets. Indeed, even packets are unable to split and recompose data, due to the unreliability of the protocol (dropped, mixed or duplicated datagrams may lead to a big mess when trying to recompose a packet).
If the socket is bound to a port, it is automatically unbound from it when the socket is destroyed. However, you can unbind the socket explicitely with the Unbind function if necessary, to stop receiving messages or make the port available for other sockets.
- int maxDatagramSize;
- The maximum number of bytes that can be sent in a single UDP datagram.
- Default constructor
- ushort getLocalPort();
- Get the port to which the socket is bound locally.
If the socket is not bound to a port, this function returns 0.
Port to which the socket is bound.
- void setBlocking(bool blocking);
- Set the blocking state of the socket.
In blocking mode, calls will not return until they have completed their task. For example, a call to Receive in blocking mode won't return until some data was actually received. In non-blocking mode, calls will always return immediately, using the return code to signal whether there was data available or not. By default, all sockets are blocking.
bool blocking True to set the socket as blocking, false for non-blocking.
- Status bind(ushort port);
- Bind the socket to a specific port.
Binding the socket to a port is necessary for being able to receive data on that port. You can use the special value Socket::AnyPort to tell the system to automatically pick an available port, and then call getLocalPort to retrieve the chosen port.
ushort port Port to bind the socket to.
- bool isBlocking();
- Tell whether the socket is in blocking or non-blocking mode.
True if the socket is blocking, false otherwise.
- Status send(const(void) data, IpAddress address, ushort port);
- Send raw data to a remote peer.
Make sure that the size is not greater than UdpSocket.MaxDatagramSize, otherwise this function will fail and no data will be sent.
const(void) data Pointer to the sequence of bytes to send. IpAddress address Address of the receiver. ushort port Port of the receiver to send the data to.
- Status send(Packet packet, IpAddress address, ushort port);
- Send a formatted packet of data to a remote peer.
Make sure that the packet size is not greater than UdpSocket.MaxDatagramSize, otherwise this function will fail and no data will be sent.
Packet packet Packet to send. IpAddress address Address of the receiver. ushort port Port of the receiver to send the data to.
- Status receive(void data, out size_t sizeReceived, out IpAddress address, out ushort port);
- Receive raw data from a remote peer.
In blocking mode, this function will wait until some bytes are actually received.
Be careful to use a buffer which is large enough for the data that you intend to receive, if it is too small then an error will be returned and all the data will be lost.
void data The array to fill with the received bytes
IpAddress address Address of the peer that sent the data ushort port Port of the peer that sent the data
- Status receive(Packet packet, out IpAddress address, out ushort port);
- Receive a formatted packet of data from a remote peer.
In blocking mode, this function will wait until the whole packet has been received.
Packet packet Packet to fill with the received data. IpAddress address Address of the peer that sent the data. ushort port Port of the peer that sent the data.
- void unbind();
- Unbind the socket from the local port to which it is bound.
The port that the socket was previously using is immediately available after this function is called. If the socket is not bound to a port, this function has no effect.