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class SF::TcpListener
inherits SF::Socket #

Socket that listens to new TCP connections

A listener socket is a special type of socket that listens to a given port and waits for connections on that port. This is all it can do.

When a new connection is received, you must call accept and the listener returns a new instance of SF::TcpSocket that is properly initialized and can be used to communicate with the new client.

Listener sockets are specific to the TCP protocol, UDP sockets are connectionless and can therefore communicate directly. As a consequence, a listener socket will always return the new connections as SF::TcpSocket instances.

A listener is automatically closed on destruction, like all other types of socket. However if you want to stop listening before the socket is destroyed, you can call its close() function.

Usage example:

# Create a listener socket and make it wait for new
# connections on port 55001
listener =

# Endless loop that waits for new connections
while running
  client =
  if listener.accept(client) == SF::Socket::Done
    # A new client just connected!
    puts "New connection received from #{client.remote_address}"
    do_something_with client

See also: SF::TcpSocket, SF::Socket



Default constructor

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#accept(socket : TcpSocket) : Socket::Status#

Accept a new connection

If the socket is in blocking mode, this function will not return until a connection is actually received.

  • socket - Socket that will hold the new connection

Returns: Status code

See also: listen

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Stop listening and close the socket

This function gracefully stops the listener. If the socket is not listening, this function has no effect.

See also: listen

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#listen(port : Int, address : IpAddress = IpAddress::Any) : Socket::Status#

Start listening for incoming connection attempts

This function makes the socket start listening on the specified port, waiting for incoming connection attempts.

If the socket is already listening on a port when this function is called, it will stop listening on the old port before starting to listen on the new port.

When providing SF::Socket::AnyPort as port, the listener will request an available port from the system. The chosen port can be retrieved by calling local_port().

  • port - Port to listen on for incoming connection attempts
  • address - Address of the interface to listen on

Returns: Status code

See also: accept, close

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#local_port : UInt16#

Get the port to which the socket is bound locally

If the socket is not listening to a port, this function returns 0.

Returns: Port to which the socket is bound

See also: listen

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