require 'msf/core'

module Msf

###
#
# This event subscriber class exposes methods that are called when internal
# framework events occur, such as the loading and creation of a module.
#
###
module GeneralEventSubscriber
	#
	# Called when a module is loaded
	#
	def on_module_load(refname, klass)
	end

	#
	# Called when a new module instance is created
	#
	def on_module_created(instance)
	end

	#
	# Called when a module is run
	#
	def on_module_run(instance)
	end

end

###
#
# This class manages subscriber registration and is the entry point
# for dispatching various events that occur for modules, such as
# exploit results and auxiliary module data. The framework
# and external modules can register themselves as subscribers to
# various events such that they can perform custom actions when
# a specific event or events occur.
#
###
class EventDispatcher

	include Framework::Offspring

	def initialize(framework)
		self.framework = framework
		self.general_event_subscribers = []
		self.exploit_event_subscribers = []
		self.session_event_subscribers = []
		self.db_event_subscribers      = []
		self.ui_event_subscribers      = []
	end

	##
	#
	# Subscriber registration
	#
	##

	#
	# This method adds a general subscriber.  General subscribers receive
	# notifications when all events occur.
	#
	def add_general_subscriber(subscriber)
		add_event_subscriber(general_event_subscribers, subscriber)
	end

	#
	# Removes a general subscriber.
	#
	def remove_general_subscriber(subscriber)
		remove_event_subscriber(general_event_subscribers, subscriber)	
	end

	#
	# This method adds a db event subscriber. db event subscribers
	# receive notifications when events occur that pertain to db changes.
	# The subscriber provided must implement the DatabaseEvent module methods
	# in some form.
	#
	def add_db_subscriber(subscriber)
		add_event_subscriber(db_event_subscribers, subscriber)
	end

	#
	# Removes a db event subscriber.
	#
	def remove_db_subscriber(subscriber)
		remove_event_subscriber(db_event_subscribers, subscriber)
	end


	#
	# This method adds an exploit event subscriber.  Exploit event subscribers
	# receive notifications when events occur that pertain to exploits, such as
	# the success or failure of an exploitation attempt.  The subscriber
	# provided must implement the ExploitEvent module methods in some form.
	#
	def add_exploit_subscriber(subscriber)
		add_event_subscriber(exploit_event_subscribers, subscriber)
	end

	#
	# Removes an exploit event subscriber.
	#
	def remove_exploit_subscriber(subscriber)
		remove_event_subscriber(exploit_event_subscribers, subscriber)
	end

	#
	# This method adds a session event subscriber.  Session event subscribers
	# receive notifications when sessions are opened and closed.  The
	# subscriber provided must implement the SessionEvent module methods in
	# some form.
	#
	def add_session_subscriber(subscriber)
		add_event_subscriber(session_event_subscribers, subscriber)
	end

	#
	# Removes a session event subscriber.
	#
	def remove_session_subscriber(subscriber)
		remove_event_subscriber(session_event_subscribers, subscriber)
	end

	##
	#
	# General events
	#
	##

	#
	# Called when a module is loaded into the framework.  This, in turn,
	# notifies all registered general event subscribers.
	#
	# This is covered by the method_missing logic, but defining it manually
	# reduces startup time by about 10%.
	#
	def on_module_load(name, mod)
		general_event_subscribers.each { |subscriber|
			subscriber.on_module_load(name, mod)
		}
	end

	#
	# Capture incoming events and pass them off to the subscribers
	#
	# When receiving an on_* event, look for a subscriber type matching the
	# type of the event.  If one exists, send the event on to each subscriber
	# of that type.  Otherwise, try to send the event each of the general
	# subscribers.
	#
	# Event method names should be like "on_<type>_<event>", e.g.:
	# on_exploit_success.
	#
	def method_missing(name, *args)

		event,type,rest = name.to_s.split("_", 3)
		subscribers = "#{type}_event_subscribers"
		found = false
		case event
		when "on"
			if respond_to?(subscribers)
				found = true
				self.send(subscribers).each do |sub|
					next if not sub.respond_to?(name)
					sub.send(name, *args)
				end
			else
				general_event_subscribers.each do |sub|
					next if not sub.respond_to?(name)
					sub.send(name, *args)
					found = true
				end
			end
		when "add"
			if respond_to?(subscribers)
				found = true
				add_event_subscriber(self.send(subscribers), *args)
			end
		when "remove"
			if respond_to?(subscribers)
				found = true
				remove_event_subscriber(self.send(subscribers), *args)
			end
		end
		if not found
			elog("Event dispatcher received an unhandled event: #{name}")
		end
		return found
	end
	
	
protected

	#
	# Adds an event subscriber to the supplied subscriber array.
	#
	def add_event_subscriber(array, subscriber) # :nodoc:
		array << subscriber
	end

	#
	# Removes an event subscriber from the supplied subscriber array.
	#
	def remove_event_subscriber(array, subscriber) # :nodoc:
		array.delete(subscriber)
	end

	attr_accessor :general_event_subscribers # :nodoc:
	attr_accessor :exploit_event_subscribers # :nodoc:
	attr_accessor :session_event_subscribers # :nodoc:
	attr_accessor :db_event_subscribers # :nodoc:	
	attr_accessor :ui_event_subscribers # :nodoc:	

end

end