sharp-coin/lib/em-bitcoin.rb

require 'eventmachine'
require 'stringio'
require 'btc_wire_proto'

module EventMachine
  module Protocols
    # Implements the TCP protocol that Bitcoin peers speak to each other. This
    # module is mixed into both incoming and outgoing connections.
    #
    # We implement the protocol as a simple(ish!) state machine. When we want
    # something doing, we call state(sym, data) to append that to the 
    # list of things to do. If something is urgent, we can call state! to
    # put it at the beginning of the list.
    #
    # Here is a list of states: 
    #  send_ver, recv_ver, verify_ver
    #  send_verack, recv_verack
    #  wait, finish
    #
    # Documentation is here: https://en.bitcoin.it/wiki/Network
    #
    # @author Nick Thomas <nick@lupine.me.uk>
    module BitcoinPeer
      
      protected
      
      # Sets up the variables required to manage the state machine. Should be
      # called before you try to push a state - in post_init, say.
      def init_state!
        @stream = StringIO.new("")
        @state_m = Mutex.new # Synchronize around @states and @working
        @state_m.synchronize do
          @states = []
          @current_state = nil
        end
      end
      
      # Checks the current configuration object to see if we have a valid config
      # or not.
      # @return[Array[true|false, msg]] Whether the config is valid, and an
      #   optional message specifying why it's invalid, if it is.
      def valid_config?
        [false, "configuration check not implemented yet"]
      end
      
      # Grabs the state that we're currently working on.
      # @return[Array[Symbol,Object]] state symbol + data
      def get_state
        @state_m.synchronize do
          @current_state ||= @states.shift
          @current_state
        end
      end
      
      # Call this when we've completed the actions required by the current state
      def finished_state
        @state_m.synchronize { @current_state = nil }
      end
      
      # Push a state to the end of the state queue.       
      def state(new_state, data = nil)
        @state_m.synchronize { @states.push(new_state, data) }
      end
      
      # Add a state to the start of the state queue.
      def state!(new_state, data = nil)
        @state_m.synchronize { @states.unshift(new_state, data) }
      end

      # Do some work on the state machine
      def state_tick
        state, data = get_state
        return unless state
        if respond_to?(state)
          send(state, data)
        else
          raise NotImplementedError.new("Unknown state: #{state} with #{data}")
        end  
      end
      
      # Receiving data mostly drives the state machine. Where something wants
      # to send data, it gets queued straight onto the I/O/
      def receive_data(io)
      end
      
      
      
      # State machine behaviours now. 
      
      # Send a 'version' message to the peer.
      # Next 
      def send_ver

      end
      
    end
    
    # EventMachine protocol class that handles an *outgoing* connection to
    # another bitcoin peer. Common functionality (p2p!) is held in BitcoinPeer.
    #
    # State machine flow: 
    #   send_ver, recv_verack
    #   recv_ver, verify_ver, send_verack
    # 
    # @author Nick Thomas <nick@lupine.me.uk>
    class BitcoinClient < EM::Connection
    include BitcoinPeer

      # @param[Object] config See the BitcoinPeer#valid_config?
      def initialize(config)
        super
        @config = config
        result, msg = valid_config?
        raise ArgumentError.new("Invalid configuration: #{msg}") unless result
        
        init_state!
      end

      def post_init
        state(:send_ver)
      end
      
      def connection_completed
        advance_state
      end
    end
    
    # EventMachine protocol class that handles an *incoming* connection from
    # another bitcoin peer. Common functionality (p2p!) is held in BitcoinPeer
    #
    # State machine flow:
    #   recv_ver, verify_ver, send_verack
    #   send_ver, recv_verack
    #
    # @author Nick Thomas <nick@lupine.me.uk>
    class BitcoinServer < EM::Connection
      include BitcoinPeer

      # @param[Object] config See the BitcoinPeer#valid_config?
      def initialize(config)
        super
        @config = config
        result, msg = valid_config?
        raise ArgumentError.new("Invalid configuration: #{msg}") unless result
        
        init_state!
      end

      def post_init
        state(:recv_ver)
      end
    end
  end
end