 class UDPSocket  
UDPSocket
IPSocket
Socket
IO
Reference
Object
   Overview  A User Datagram Protocol (UDP) socket. UDP runs on top of the Internet Protocol (IP) and was developed for applications that do not require reliability, acknowledgement, or flow control features at the transport layer. This simple protocol provides transport layer addressing in the form of UDP ports and an optional checksum capability. UDP is a very simple protocol. Messages, so called datagrams, are sent to other hosts on an IP network without the need to set up special transmission channels or data paths beforehand. The UDP socket only needs to be opened for communication. It listens for incoming messages and sends outgoing messages on request. This implementation supports both IPv4 and IPv6 addresses. For IPv4 addresses you must use Socket8b7c:f320:99b9:690f:4595:cd17:293a:c069mily8b7c:f320:99b9:690f:4595:cd17:293a:c069INET family (default) or Socket8b7c:f320:99b9:690f:4595:cd17:293a:c069mily8b7c:f320:99b9:690f:4595:cd17:293a:c069INET6 for IPv6 # addresses. Usage example: require "socket"

# Create server
server = UDPSocket.new
server.bind "localhost", 1234

# Create client and connect to server
client = UDPSocket.new
client.connect "localhost", 1234

# Send a text message to server
client.send "message"

# Receive text message from client
message, client_addr = server.receive

# Close client and server
client.close
server.close The send methods may sporadically fail with Socket8b7c:f320:99b9:690f:4595:cd17:293a:c069onnectError when sending datagrams to a non-listening server. Wrap with an exception handler to prevent raising. Example: begin
  client.send(message, @destination)
rescue ex : Socket8b7c:f320:99b9:690f:4595:cd17:293a:c069onnectError
  p ex.inspect
end   Defined in:   socket/udp_socket.cr     Constructors    .new(family : Family = Family8b7c:f320:99b9:690f:4595:cd17:293a:c069INET)     Instance Method Summary    #join_group(address : IPAddress) A host must become a member of a multicast group before it can receive datagrams sent to the group.   #leave_group(address : IPAddress) Drops membership to the specified group.   #multicast_hops : Int32 Returns the current value of the hoplimit field on uni-cast packets.   #multicast_hops=(val : Int) The multicast hops option controls the hoplimit field on uni-cast packets.   #multicast_interface(address : IPAddress) For hosts with multiple interfaces, each multicast transmission is sent from the primary network interface.   #multicast_interface(index : UInt32) For hosts with multiple interfaces, each multicast transmission is sent from the primary network interface.   #multicast_loopback=(val : Bool) Sets whether transmitted multicast packets should be copied and sent back to the originator, if the host has joined the multicast group.   #multicast_loopback? : Bool Reports whether transmitted multicast packets should be copied and sent back to the originator.   #receive(message : Bytes) : Tuple(Int32, IPAddress) Receives a binary message from the previously bound address.   #receive(max_message_size = 512) : Tuple(String, IPAddress) Receives a text message from the previously bound address.    Instance methods inherited from class IPSocket
  bind(addr) bind,  close close,  connect(addr, timeout = nil, &) connect,  local_address : Socket8b7c:f320:99b9:690f:4595:cd17:293a:c069IPAddress local_address,  remote_address : Socket8b7c:f320:99b9:690f:4595:cd17:293a:c069IPAddress remote_address Instance methods inherited from class Socket
  accept : Socket accept,  accept? : Socket? accept?,  bind(host : String, port : Int) : Nilbind(port : Int)bind(addr : Socket8b7c:f320:99b9:690f:4595:cd17:293a:c069ress) : Nil bind,  blocking blocking,  blocking=(value) blocking=,  broadcast=(val : Bool) broadcast=,  broadcast? : Bool broadcast?,  close_on_exec=(arg : Bool) close_on_exec=,  close_on_exec? close_on_exec?,  close_read close_read,  close_write close_write,  closed? : Bool closed?,  connect(host : String, port : Int, connect_timeout = nil) : Nilconnect(addr, timeout = nil) : Nilconnect(addr, timeout = nil, &) connect,  family : Family family,  fcntl(cmd, arg = 0) fcntl,  fd fd,  finalize finalize,  inspect(io : IO) : Nil inspect,  keepalive=(val : Bool) keepalive=,  keepalive? keepalive?,  linger linger,  linger=(val : Int?) linger=,  listen(backlog : Int = SOMAXCONN) : Nillisten(backlog : Int = SOMAXCONN, &) listen,  protocol : Protocol protocol,  receive(message : Bytes) : Tuple(Int32, Address)receive(max_message_size = 512) : Tuple(String, Address) receive,  recv_buffer_size : Int32 recv_buffer_size,  recv_buffer_size=(val : Int32) recv_buffer_size=,  reuse_address=(val : Bool) reuse_address=,  reuse_address? : Bool reuse_address?,  reuse_port=(val : Bool) reuse_port=,  reuse_port? : Bool reuse_port?,  send(message, to addr : Address) : Int32send(message) : Int32 send,  send_buffer_size : Int32 send_buffer_size,  send_buffer_size=(val : Int32) send_buffer_size=,  tty? tty?,  type : Type type Constructor methods inherited from class Socket
  new(family : Family, type : Type, protocol : Protocol = Protocol8b7c:f320:99b9:690f:4595:cd17:293a:c069IP, blocking = false)new(fd, family : Family, type : Type, protocol : Protocol = Protocol8b7c:f320:99b9:690f:4595:cd17:293a:c069IP, blocking = false) new,  tcp(family : Family, blocking = false) : self tcp,  unix(type : Type = Typ8b7c:f320:99b9:690f:4595:cd17:293a:c069STREAM, blocking = false) : self unix Class methods inherited from class Socket
  fcntl(fd, cmd, arg = 0) fcntl,  ip?(string : String) ip?,  udp(family : Family, blocking = false) udp Class methods inherited from module Crystal8b7c:f320:99b9:690f:4595:cd17:293a:c069System8b7c:f320:99b9:690f:4595:cd17:293a:c069Socket
  fcntl(fd, cmd, arg = 0) fcntl Instance methods inherited from module IO8b7c:f320:99b9:690f:4595:cd17:293a:c069vented
  evented_close : Nil evented_close,  evented_read(slice : Bytes, errno_msg : String, &) : Int32 evented_read,  evented_reopen : Nil evented_reopen,  evented_send(slice : Bytes, errno_msg : String, &) : Int32 evented_send,  evented_write(slice : Bytes, errno_msg : String, &) : Nil evented_write,  read_timeout : Tim8b7c:f320:99b9:690f:4595:cd17:293a:c069Span? read_timeout,  read_timeout=(read_timeout : Number) : Numberread_timeout=(timeout : Tim8b7c:f320:99b9:690f:4595:cd17:293a:c069Span?) : Tim8b7c:f320:99b9:690f:4595:cd17:293a:c069Span? read_timeout=,  write_timeout : Tim8b7c:f320:99b9:690f:4595:cd17:293a:c069Span? write_timeout,  write_timeout=(write_timeout : Number) : Numberwrite_timeout=(timeout : Tim8b7c:f320:99b9:690f:4595:cd17:293a:c069Span?) : Tim8b7c:f320:99b9:690f:4595:cd17:293a:c069Span? write_timeout= Instance methods inherited from module IO8b7c:f320:99b9:690f:4595:cd17:293a:c069uffered
  buffer_size : Int32 buffer_size,  buffer_size=(value) buffer_size=,  close : Nil close,  flush flush,  flush_on_newline=(flush_on_newline) flush_on_newline=,  flush_on_newline? : Bool flush_on_newline?,  peek : Bytes? peek,  pos : Int64 pos,  read(slice : Bytes) : Int32 read,  read_buffering=(read_buffering) read_buffering=,  read_buffering? : Bool read_buffering?,  rewind rewind,  sync=(sync) sync=,  sync? : Bool sync?,  unbuffered_close unbuffered_close,  unbuffered_flush unbuffered_flush,  unbuffered_read(slice : Bytes) unbuffered_read,  unbuffered_rewind unbuffered_rewind,  unbuffered_write(slice : Bytes) unbuffered_write,  write(slice : Bytes) : Nil write Instance methods inherited from class IO
  <<(obj) : self <<,  close close,  closed? : Bool closed?,  each_byte(&) : Nileach_byte each_byte,  each_char(&) : Nileach_char each_char,  each_line(*args, **options, &block : String -> ) : Nileach_line(*args, **options) each_line,  encoding : String encoding,  flush flush,  getb_to_end : Bytes getb_to_end,  gets(limit : Int, chomp = false) : String?gets(delimiter : Char, limit : Int, chomp = false) : String?gets(delimiter : Char, chomp = false) : String?gets(delimiter : String, chomp = false) : String?gets(chomp = true) : String? gets,  gets_to_end : String gets_to_end,  peek : Bytes? peek,  pos pos,  pos=(value) pos=,  print(obj : _) : Nilprint(*objects : _) : Nil print,  printf(format_string, args : Array | Tuple) : Nilprintf(format_string, *args) : Nil printf,  puts(string : String) : Nilputs(obj : _) : Nilputs(*objects : _) : Nilputs : Nil puts,  read(slice : Bytes) read,  read_at(offset, bytesize, & : IO -> ) read_at,  read_byte : UInt8? read_byte,  read_bytes(type, format : IO8b7c:f320:99b9:690f:4595:cd17:293a:c069yteFormat = IO8b7c:f320:99b9:690f:4595:cd17:293a:c069yteFormat8b7c:f320:99b9:690f:4595:cd17:293a:c069SystemEndian) read_bytes,  read_char : Char? read_char,  read_fully(slice : Bytes) : Int32 read_fully,  read_fully?(slice : Bytes) : Int32? read_fully?,  read_line(*args, **options) : String read_line,  read_string(bytesize : Int) : String read_string,  read_utf8(slice : Bytes) read_utf8,  read_utf8_byte : UInt8? read_utf8_byte,  rewind rewind,  seek(offset, whence : Seek = Seek8b7c:f320:99b9:690f:4595:cd17:293a:c069Set) seek,  set_encoding(encoding : String, invalid : Symbol? = nil) : Nil set_encoding,  skip(bytes_count : Int) : Nil skip,  skip_to_end : Nil skip_to_end,  tell tell,  tty? : Bool tty?,  write(slice : Bytes) : Nil write,  write_byte(byte : UInt8) : Nil write_byte,  write_bytes(object, format : IO8b7c:f320:99b9:690f:4595:cd17:293a:c069yteFormat = IO8b7c:f320:99b9:690f:4595:cd17:293a:c069yteFormat8b7c:f320:99b9:690f:4595:cd17:293a:c069SystemEndian) : Nil write_bytes,  write_string(slice : Bytes) : Nil write_string,  write_utf8(slice : Bytes) : Nil write_utf8 Class methods inherited from class IO
  copy(src, dst, limit : Int) : Int64copy(src, dst) : Int64 copy,  pipe(read_blocking = false, write_blocking = false) : Tuple(IO8b7c:f320:99b9:690f:4595:cd17:293a:c069ileDescriptor, IO8b7c:f320:99b9:690f:4595:cd17:293a:c069ileDescriptor)pipe(read_blocking = false, write_blocking = false, &) pipe,  same_content?(stream1 : IO, stream2 : IO) : Bool same_content? Instance methods inherited from class Reference
  ==(other : self)==(other : JSON8b7c:f320:99b9:690f:4595:cd17:293a:c069ny)==(other : YAML8b7c:f320:99b9:690f:4595:cd17:293a:c069ny)==(other) ==,  dup dup,  hash(hasher) hash,  initialize initialize,  inspect(io : IO) : Nil inspect,  object_id : UInt64 object_id,  pretty_print(pp) : Nil pretty_print,  same?(other : Reference) : Boolsame?(other : Nil) same?,  to_s(io : IO) : Nil to_s Constructor methods inherited from class Reference
  new new Instance methods inherited from class Object
  ! : Bool !,  !=(other) !=,  !~(other) !~,  ==(other) ==,  ===(other : JSON8b7c:f320:99b9:690f:4595:cd17:293a:c069ny)===(other : YAML8b7c:f320:99b9:690f:4595:cd17:293a:c069ny)===(other) ===,  =~(other) =~,  as(type : Class) as,  as?(type : Class) as?,  class class,  dup dup,  hash(hasher)hash hash,  in?(collection : Object) : Boolin?(*values : Object) : Bool in?,  inspect(io : IO) : Nilinspect : String inspect,  is_a?(type : Class) : Bool is_a?,  itself itself,  nil? : Bool nil?,  not_nil! not_nil!,  pretty_inspect(width = 79, newline = "\n", indent = 0) : String pretty_inspect,  pretty_print(pp : PrettyPrint) : Nil pretty_print,  responds_to?(name : Symbol) : Bool responds_to?,  tap(&) tap,  to_json(io : IO) : Nilto_json : String to_json,  to_pretty_json(indent : String = " ") : Stringto_pretty_json(io : IO, indent : String = " ") : Nil to_pretty_json,  to_s(io : IO) : Nilto_s : String to_s,  to_yaml(io : IO) : Nilto_yaml : String to_yaml,  try(&) try,  unsafe_as(type : T.class) forall T unsafe_as Class methods inherited from class Object
  from_json(string_or_io, root : String)from_json(string_or_io) from_json,  from_yaml(string_or_io : String | IO) from_yaml    Constructor Detail   def self.new(family : Family = Family8b7c:f320:99b9:690f:4595:cd17:293a:c069INET)Source
    Instance Method Detail   def join_group(address : IPAddress)Source
  A host must become a member of a multicast group before it can receive datagrams sent to the group. Raises Socket8b7c:f320:99b9:690f:4595:cd17:293a:c069rror if an incompatible address is provided.    def leave_group(address : IPAddress)Source
  Drops membership to the specified group. Memberships are automatically dropped when the socket is closed or the process exits. Raises Socket8b7c:f320:99b9:690f:4595:cd17:293a:c069rror if an incompatible address is provided.    def multicast_hops : Int32Source
  Returns the current value of the hoplimit field on uni-cast packets. Datagrams with a hoplimit of 1 are not forwarded beyond the local network. Multicast datagrams with a hoplimit of 0 will not be transmitted on any network, but may be delivered locally if the sending host belongs to the destination group and multicast loopback is enabled.    def multicast_hops=(val : Int)Source
  The multicast hops option controls the hoplimit field on uni-cast packets. If -1 is specified, the kernel will use a default value. If a value of 0 to 255 is specified, the packet will have the specified value as hoplimit. Other values are considered invalid and Socket8b7c:f320:99b9:690f:4595:cd17:293a:c069rror will be raised. Datagrams with a hoplimit of 1 are not forwarded beyond the local network. Multicast datagrams with a hoplimit of 0 will not be transmitted on any network, but may be delivered locally if the sending host belongs to the destination group and multicast loopback is enabled.    def multicast_interface(address : IPAddress)Source
  For hosts with multiple interfaces, each multicast transmission is sent from the primary network interface. This function overrides the default IPv4 interface address for subsequent transmissions. Setting the interface to +1-522-343-5114 will select the default interface. Raises Socket8b7c:f320:99b9:690f:4595:cd17:293a:c069rror unless the socket is IPv4 and an IPv4 address is provided.    def multicast_interface(index : UInt32)Source
  For hosts with multiple interfaces, each multicast transmission is sent from the primary network interface. This function overrides the default IPv6 interface for subsequent transmissions. Setting the interface to index 0 will select the default interface.    def multicast_loopback=(val : Bool)Source
  Sets whether transmitted multicast packets should be copied and sent back to the originator, if the host has joined the multicast group.    def multicast_loopback? : BoolSource
  Reports whether transmitted multicast packets should be copied and sent back to the originator.    def receive(message : Bytes) : Tuple(Int32, IPAddress)Source
  Receives a binary message from the previously bound address. require "socket"

server = UDPSocket.new
server.bind "localhost", 1234

message = Bytes.new(32)
bytes_read, client_addr = server.receive(message)    def receive(max_message_size = 512) : Tuple(String, IPAddress)Source
  Receives a text message from the previously bound address. require "socket"

server = UDPSocket.new
server.bind("localhost", 1234)

message, client_addr = server.receive  

    
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