class Socket

• Socket
• IO
• Reference
• Object

Included Modules

• Crystal::System::Socket
• IO::Buffered

Direct Known Subclasses

• IPSocket
• UNIXSocket

Defined in:

Constructors

• .new(family : Family, type : Type, protocol : Protocol = Protocol::IP, blocking = false)
• .new(fd, family : Family, type : Type, protocol : Protocol = Protocol::IP, blocking = false)

  Creates a Socket from an existing socket file descriptor / handle.

• .tcp(family : Family, blocking = false) : self

  Creates a TCP socket.

• .unix(type : Type = Type::STREAM, blocking = false) : self

  Creates an UNIX socket.

Class Method Summary

• .fcntl(fd, cmd, arg = 0)
• .ip?(string : String)

  Returns true if the string represents a valid IPv4 or IPv6 address.

  DEPRECATED Use IPAddress.valid? instead

• .udp(family : Family, blocking = false)

  Creates an UDP socket.

Instance Method Summary

• #accept : Socket

  Accepts an incoming connection.

• #accept? : Socket | Nil

  Accepts an incoming connection.

• #bind(host : String, port : Int) : Nil

  Binds the socket to a local address.

• #bind(port : Int)

  Binds the socket on port to all local interfaces.

• #bind(addr : Socket::Address) : Nil

  Binds the socket to a local address.

• #blocking
• #blocking=(value)
• #broadcast=(val : Bool)
• #broadcast? : Bool
• #close_on_exec=(arg : Bool)
• #close_on_exec?
• #close_read

  Calls shutdown(2) with SHUT_RD

• #close_write

  Calls shutdown(2) with SHUT_WR

• #closed? : Bool

  Returns true if this IO is closed.

• #connect(host : String, port : Int, connect_timeout = nil) : Nil

  Connects the socket to a remote host:port.

• #connect(addr, timeout = nil) : Nil

  Connects the socket to a remote address.

• #connect(addr, timeout = nil, &)

  Tries to connect to a remote address.

• #family : Family
• #fcntl(cmd, arg = 0)
• #fd

  Returns the handle associated with this socket from the operating system.

• #finalize
• #inspect(io : IO) : Nil

  Appends a String representation of this object which includes its class name, its object address and the values of all instance variables.

• #keepalive=(val : Bool)
• #keepalive?
• #linger
• #linger=(val : Int | Nil)

  WARNING The behavior of SO_LINGER is platform specific.

• #listen(backlog : Int = SOMAXCONN) : Nil

  Tells the previously bound socket to listen for incoming connections.

• #listen(backlog : Int = SOMAXCONN, &)

  Tries to listen for connections on the previously bound socket.

• #protocol : Protocol
• #receive(message : Bytes) : Tuple(Int32, Address)

  Receives a binary message from the previously bound address.

• #receive(max_message_size = 512) : Tuple(String, Address)

  Receives a text message from the previously bound address.

• #recv_buffer_size : Int32
• #recv_buffer_size=(val : Int32)
• #reuse_address=(val : Bool)
• #reuse_address? : Bool
• #reuse_port=(val : Bool)
• #reuse_port? : Bool
• #send(message, to addr : Address) : Int32

  Sends a message to the specified remote address.

• #send(message) : Int32

  Sends a message to a previously connected remote address.

• #send_buffer_size : Int32
• #send_buffer_size=(val : Int32)
• #tty?

  Returns true if this IO is associated with a terminal device (tty), false otherwise.

• #type : Type

Constructor Detail

Class Method Detail

Instance Method Detail

require "socket"

server = TCPServer.new(2202)
socket = server.accept
socket.puts Time.utc
socket.close

require "socket"

server = TCPServer.new(2202)
if socket = server.accept?
  socket.puts Time.utc
  socket.close
end

require "socket"

sock = Socket.tcp(Socket::Family::INET)
sock.bind "localhost", 1234

require "socket"

sock = Socket.tcp(Socket::Family::INET6)
sock.bind 1234

require "socket"

sock = Socket.udp(Socket::Family::INET)
sock.bind Socket::IPAddress.new("192.168.1.25", 80)

require "socket"

sock = Socket.tcp(Socket::Family::INET)
sock.connect "crystal-lang.org", 80

require "socket"

sock = Socket.unix
sock.connect Socket::UNIXAddress.new("/tmp/service.sock")

class Person
  def initialize(@name : String, @age : Int32)
  end
end

Person.new("John", 32).inspect # => #<Person:0x10fd31f20 @name="John", @age=32>

require "socket"

server = Socket.udp(Socket::Family::INET)
server.bind("localhost", 1234)

message = Bytes.new(32)
bytes_read, client_addr = server.receive(message)

require "socket"

server = Socket.udp(Socket::Family::INET)
server.bind("localhost", 1234)

message, client_addr = server.receive

require "socket"

server = Socket::IPAddress.new("10.0.3.1", 2022)
sock = Socket.udp(Socket::Family::INET)
sock.connect("example.com", 2000)
sock.send("text query", to: server)

require "socket"

sock = Socket.udp(Socket::Family::INET)
sock.connect("example.com", 2000)
sock.send("text message")

sock = Socket.unix(Socket::Type::DGRAM)
sock.connect Socket::UNIXAddress.new("/tmp/service.sock")
sock.send(Bytes[0])

STDIN.tty?          # => true
IO::Memory.new.tty? # => false