celluloid/celluloid-dns

# Copyright, 2009, 2012, by Samuel G. D. Williams. <http://www.codeotaku.com>
# 
# Permission is hereby granted, free of charge, to any person obtaining a copy
# of this software and associated documentation files (the "Software"), to deal
# in the Software without restriction, including without limitation the rights
# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
# copies of the Software, and to permit persons to whom the Software is
# furnished to do so, subject to the following conditions:
# 
# The above copyright notice and this permission notice shall be included in
# all copies or substantial portions of the Software.
# 
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
# THE SOFTWARE.

require 'stringio'
require 'ipaddr'

require_relative 'message'

module Celluloid::DNS
    def self.address_family(host)
        return IPAddr.new(host).family
    end
    
    # A helper class for processing incoming network data.
    class BinaryStringIO < StringIO
        def initialize
            super
        
            set_encoding("BINARY")
        end
    end
    
    module StreamTransport
        def self.read_chunk(socket)
            # The data buffer:
            buffer = BinaryStringIO.new
            
            # First we need to read in the length of the packet
            while buffer.size < 2
                buffer.write socket.readpartial(1)
            end
            
            # Read in the length, the first two bytes:
            length = buffer.string.byteslice(0, 2).unpack('n')[0]
            
            # Read data until we have the amount specified:
            while (buffer.size - 2) < length
                required = (2 + length) - buffer.size
                
                # Read precisely the required amount:
                buffer.write socket.readpartial(required)
            end
            
            return buffer.string.byteslice(2, length)
        end
        
        def self.write_message(socket, message)
            write_chunk(socket, message.encode)
        end
        
        def self.write_chunk(socket, output_data)
            # TODO: We need to check that the data was written completely and didn't fail!
            socket.write([output_data.bytesize].pack('n'))
            socket.write(output_data)
            
            return output_data.bytesize
        end
    end
end