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udp_socket.cr
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udp_socket.cr
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require "./ip_socket"
# 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
# `Socket::Family::INET` family (default) or `Socket::Family::INET6` 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 `Errno::ECONNREFUSED` when sending datagrams
# to a non-listening server.
# Wrap with an exception handler to prevent raising. Example:
#
# ```
# begin
# client.send(message, @destination)
# rescue ex : Errno
# if ex.errno == Errno::ECONNREFUSED
# p ex.inspect
# end
# end
# ```
class UDPSocket < IPSocket
def initialize(family : Family = Family::INET)
super(family, Type::DGRAM, Protocol::UDP)
end
# Receives a text message from the previously bound address.
#
# ```
# server = UDPSocket.new
# server.bind("localhost", 1234)
#
# message, client_addr = server.receive
# ```
def receive(max_message_size = 512) : {String, IPAddress}
address = nil
message = String.new(max_message_size) do |buffer|
bytes_read, sockaddr, addrlen = recvfrom(Slice.new(buffer, max_message_size))
address = IPAddress.from(sockaddr, addrlen)
{bytes_read, 0}
end
{message, address.not_nil!}
end
# Receives a binary message from the previously bound address.
#
# ```
# server = UDPSocket.new
# server.bind "localhost", 1234
#
# message = Bytes.new(32)
# bytes_read, client_addr = server.receive(message)
# ```
def receive(message : Bytes) : {Int32, IPAddress}
bytes_read, sockaddr, addrlen = recvfrom(message)
{bytes_read, IPAddress.from(sockaddr, addrlen)}
end
end