cmol

require 'socket'
require 'ipaddr'

def get_interface_info(name)
  ifaddrs = Socket.getifaddrs.reject do |ifaddr|
    !ifaddr.addr&.ipv6_linklocal? || (ifaddr.flags & Socket::IFF_MULTICAST == 0)
  end
  ifaddrs.select! {|ifaddr| ifaddr.name == name } if name
  ifaddrs.map {|ifaddr| [ifaddr.name, ifaddr.ifindex, ifaddr.addr.ip_address] }
end

cmol

def create_socket(multicast_addr, multicast_port, ifindex)
  # Create, bind, and return a UDP multicast socket
  UDPSocket.new(Socket::AF_INET6).tap do | s |
    ip = IPAddr.new(multicast_addr).hton + [ifindex].pack('I')
    s.setsockopt(Socket::IPPROTO_IPV6, Socket::IPV6_JOIN_GROUP, ip)
    s.setsockopt(Socket::IPPROTO_IPV6, Socket::IPV6_MULTICAST_HOPS, [1].pack('I'))
    s.setsockopt(Socket::IPPROTO_IPV6, Socket::IPV6_MULTICAST_IF, [ifindex].pack('I'))
    s.bind("::", multicast_port)
  end
end

cmol

require "socket"

LISTEN_ADDR = "::"
LISTEN_PORT = 12345
MSG_LENGTH  = 256
FLAGS       = 0

# Create socket and bind it to the listen on all addresses and the given port
server_socket = UDPSocket.new :INET6
server_socket.bind(LISTEN_ADDR, LISTEN_PORT)

cmol

addr_info = Addrinfo.new(client)
puts "Client connected from #{addr_info.ip_address} using " +
  "#{addr_info.ipv6_v4mapped? ? "IPv4" : "IPv6"}"

cmol

def echo_listener(socket, linklocal_addr, multicast_addr, multicast_port,
                  flags, msg_length)
  loop do
    # Listen for messages of up to specified length
    message, client = socket.recvfrom(msg_length)

    # Extract client information given as array and log connection
    addr_info = Addrinfo.new(client)

    # We are not interested in messages from our selves

cmol

def get_interface_info(name)
  ifaddrs = Socket.getifaddrs.reject do |ifaddr|
    !ifaddr.addr&.ipv6_linklocal? || (ifaddr.flags & Socket::IFF_MULTICAST == 0)
  end
  ifaddrs.select! {|ifaddr| ifaddr.name == name } if name
  ifaddrs.map {|ifaddr| [ifaddr.name, ifaddr.ifindex, ifaddr.addr.ip_address] }
end

cmol

message, client = server_socket.recvfrom(MSG_LENGTH)

cmol

require "socket"

CONNECT_ADDR = "localhost"
CONNECT_PORT = 12345
MSG_LENGTH  = 256
FLAGS       = 0

Addrinfo.udp(CONNECT_ADDR, CONNECT_PORT).connect do |socket|
  socket.send("Connected via unspecified address family socket", FLAGS)
  message, server = socket.recvfrom(MSG_LENGTH)

cmol

cmol@qui-gon:~$ ruby echo_client_udp.rb
[IPv6] Connected via unspecified address family socket

cmol

cmol@qui-gon:~$ nc -4 -u localhost 12345
Hello from IPv4!
[IPv4] Hello from IPv4!

cmol@qui-gon:~$ nc -6 -u localhost 12345
Hello from IPv6!
[IPv6] Hello from IPv6!