bonjour_chat.rb

# http://dnssd.rubyforge.org/dnssd/
# http://xmpp.org/extensions/xep-0174.html
# http://home.gna.org/xmpp4r/

require 'rubygems'
require 'dnssd'
require 'xmpp4r'

# An example of how to send messages to iChat with the bonjour chat protocol
# using ruby.

# This makes it easier to see where things go wrong
Thread.abort_on_exception = true

name = "foo@bar"          # name@location
type = "_presence._tcp"   # the mDNS service type
domain = "local"          # the subnet we're on, almost always 'local'
port = 5000               # the port other people can contact us on
txt_record = DNSSD::TextRecord.new(
 "txtvers" => "1",                            # required, always 1
 "port.p2pj" => port,                         # for back compatibility
 "status" => "avail",                         # avail, away, or dnd
 "1st" => name.split(/@/).first.capitalize)   # The name other people see

# Announce our availability
# ! method runs in the current thread, without the ! a new thread is created,
# but not joined, so we'd fall through and exit.
DNSSD.register!(name, type, domain, port, txt_record) do |registered|
  
  # Find some other users
  browser = DNSSD::Service.new
  browser.browse(type) do |browsed|
    # skip any results that tell us they have more details coming
    next if browsed.flags.to_i & DNSSD::Flags::MoreComing > 0
    # skip if the user is us
    next if browsed.fullname == registered.fullname
    # stop when we've found someone
    browser.stop
    
    # discover the host and port to comunicate with this user on
    resolver = DNSSD::Service.new
    resolver.resolve(browsed.name, browsed.type, browsed.domain) do |resolved|
      next if resolved.flags.to_i & DNSSD::Flags::MoreComing > 0
      # stop as soon as we have resolved the user
      resolver.stop
      
      # the protocol is pretty much just XMPP/jabber
      jid = Jabber::JID.new(name)
      client = Jabber::Client.new(jid)
      # for some reason we have to wait a little before we connect
      sleep 0.5
      # connect to the host/port we got from resolving the user
      client.connect(resolved.target, resolved.port)
      # construct and send our message
      message = Jabber::Message.new(resolved.name, "hi")
      client.send(message)
      # and we're done
      client.close
      exit
    end
  end
end