#!/usr/bin/env ruby

require 'socket'
require 'openssl'

require 'rex/script'
require 'rex/post/meterpreter/client_core'
require 'rex/post/meterpreter/channel'
require 'rex/post/meterpreter/channel_container'
require 'rex/post/meterpreter/dependencies'
require 'rex/post/meterpreter/object_aliases'
require 'rex/post/meterpreter/packet'
require 'rex/post/meterpreter/packet_parser'
require 'rex/post/meterpreter/packet_dispatcher'

module Rex
module Post
module Meterpreter

#
# Just to get it in there...
#
module Extensions
end

###
#
# This class represents a logical meterpreter client class.  This class
# provides an interface that is compatible with the Rex post-exploitation
# interface in terms of the feature set that it attempts to expose.  This
# class is meant to drive a single meterpreter client session.
#
###
class Client

	include Rex::Post::Meterpreter::PacketDispatcher
	include Rex::Post::Meterpreter::ChannelContainer

	#
	# Extension name to class hash.
	#
	@@ext_hash = {}

	#
	# Cached SSL certificate (required to scale)
	#
	@@ssl_ctx = nil

	#
	# Mutex to synchronize class-wide operations
	#
	@@ssl_mutex = ::Mutex.new

	#
	# Lookup the error that occurred
	#
	def self.lookup_error(code)
		code
	end

	#
	# Checks the extension hash to see if a class has already been associated
	# with the supplied extension name.
	#
	def self.check_ext_hash(name)
		@@ext_hash[name]
	end

	#
	# Stores the name to class association for the supplied extension name.
	#
	def self.set_ext_hash(name, klass)
		@@ext_hash[name] = klass
	end

	#
	# Initializes the client context with the supplied socket through
	# which communication with the server will be performed.
	#
	def initialize(sock,opts={})
		init_meterpreter(sock, opts)
	end

	#
	# Cleans up the meterpreter instance, terminating the dispatcher thread.
	#
	def cleanup_meterpreter
		ext.aliases.each_value do | extension |
			extension.cleanup if extension.respond_to?( 'cleanup' )
		end
		dispatcher_thread.kill if dispatcher_thread
		core.shutdown rescue nil
		shutdown_passive_dispatcher
	end

	#
	# Initializes the meterpreter client instance
	#
	def init_meterpreter(sock,opts={})
		self.sock         = sock
		self.parser       = PacketParser.new
		self.ext          = ObjectAliases.new
		self.ext_aliases  = ObjectAliases.new
		self.alive        = true
		self.target_id    = opts[:target_id]
		self.capabilities = opts[:capabilities] || {}


		self.conn_id      = opts[:conn_id]
		self.url          = opts[:url]
		self.ssl          = opts[:ssl]
		self.expiration   = opts[:expiration]
		self.comm_timeout = opts[:comm_timeout]
		self.passive_dispatcher = opts[:passive_dispatcher]

		self.response_timeout = opts[:timeout] || self.class.default_timeout
		self.send_keepalives  = true
		# self.encode_unicode   = opts.has_key?(:encode_unicode) ? opts[:encode_unicode] : true
		self.encode_unicode = false

		if opts[:passive_dispatcher]
			initialize_passive_dispatcher

			register_extension_alias('core', ClientCore.new(self))

			initialize_inbound_handlers
			initialize_channels

			# Register the channel inbound packet handler
			register_inbound_handler(Rex::Post::Meterpreter::Channel)
		else
			# Switch the socket to SSL mode and receive the hello if needed
			if capabilities[:ssl] and not opts[:skip_ssl]
				swap_sock_plain_to_ssl()
			end

			register_extension_alias('core', ClientCore.new(self))

			initialize_inbound_handlers
			initialize_channels

			# Register the channel inbound packet handler
			register_inbound_handler(Rex::Post::Meterpreter::Channel)

			monitor_socket
		end
	end

	def swap_sock_plain_to_ssl
		# Create a new SSL session on the existing socket
		ctx = generate_ssl_context()
		ssl = OpenSSL::SSL::SSLSocket.new(sock, ctx)

		if not ssl.respond_to?(:accept_nonblock)
			ssl.accept
		else
			begin
				ssl.accept_nonblock

			# Ruby 1.8.7 and 1.9.0/1.9.1 uses a standard Errno
			rescue ::Errno::EAGAIN, ::Errno::EWOULDBLOCK
					IO::select(nil, nil, nil, 0.10)
					retry

			# Ruby 1.9.2+ uses IO::WaitReadable/IO::WaitWritable
			rescue ::Exception => e
				if ::IO.const_defined?('WaitReadable') and e.kind_of?(::IO::WaitReadable)
					IO::select( [ ssl ], nil, nil, 0.10 )
					retry
				end

				if ::IO.const_defined?('WaitWritable') and e.kind_of?(::IO::WaitWritable)
					IO::select( nil, [ ssl ], nil, 0.10 )
					retry
				end

				raise e
			end
		end

		self.sock.extend(Rex::Socket::SslTcp)
		self.sock.sslsock = ssl
		self.sock.sslctx  = ctx

		tag = self.sock.get_once(-1, 30)
		if(not tag or tag !~ /^GET \//)
			raise RuntimeError, "Could not read the HTTP hello token"
		end
	end

	def swap_sock_ssl_to_plain
		# Remove references to the SSLSocket and Context
		self.sock.sslsock.close
		self.sock.sslsock = nil
		self.sock.sslctx  = nil
		self.sock = self.sock.fd
		self.sock.extend(::Rex::Socket::Tcp)
	end

	def generate_ssl_context
		@@ssl_mutex.synchronize do
		if not @@ssl_ctx

		wlog("Generating SSL certificate for Meterpreter sessions")

		key  = OpenSSL::PKey::RSA.new(1024){ }
		cert = OpenSSL::X509::Certificate.new
		cert.version = 2
		cert.serial  = rand(0xFFFFFFFF)

		subject = OpenSSL::X509::Name.new([
				["C","US"],
				['ST', Rex::Text.rand_state()],
				["L", Rex::Text.rand_text_alpha(rand(20) + 10)],
				["O", Rex::Text.rand_text_alpha(rand(20) + 10)],
				["CN", self.sock.getsockname[1] || Rex::Text.rand_hostname],
			])
		issuer = OpenSSL::X509::Name.new([
				["C","US"],
				['ST', Rex::Text.rand_state()],
				["L", Rex::Text.rand_text_alpha(rand(20) + 10)],
				["O", Rex::Text.rand_text_alpha(rand(20) + 10)],
				["CN", Rex::Text.rand_text_alpha(rand(20) + 10)],
			])

		cert.subject = subject
		cert.issuer = issuer
		cert.not_before = Time.now - (3600 * 365) + rand(3600 * 14)
		cert.not_after = Time.now + (3600 * 365) + rand(3600 * 14)
		cert.public_key = key.public_key
		ef = OpenSSL::X509::ExtensionFactory.new(nil,cert)
		cert.extensions = [
			ef.create_extension("basicConstraints","CA:FALSE"),
			ef.create_extension("subjectKeyIdentifier","hash"),
			ef.create_extension("extendedKeyUsage","serverAuth"),
			ef.create_extension("keyUsage","keyEncipherment,dataEncipherment,digitalSignature")
		]
		ef.issuer_certificate = cert
		cert.add_extension ef.create_extension("authorityKeyIdentifier", "keyid:always,issuer:always")
		cert.sign(key, OpenSSL::Digest::SHA1.new)

		ctx = OpenSSL::SSL::SSLContext.new(:SSLv3)
		ctx.key = key
		ctx.cert = cert

		ctx.session_id_context = Rex::Text.rand_text(16)

		wlog("Generated SSL certificate for Meterpreter sessions")

		@@ssl_ctx = ctx

		end # End of if not @ssl_ctx
		end # End of mutex.synchronize

		@@ssl_ctx
	end

	##
	#
	# Accessors
	#
	##

	#
	# Returns the default timeout that request packets will use when
	# waiting for a response.
	#
	def Client.default_timeout
		return 300
	end

	##
	#
	# Alias processor
	#
	##

	#
	# Translates unhandled methods into registered extension aliases
	# if a matching extension alias exists for the supplied symbol.
	#
	def method_missing(symbol, *args)
		self.ext_aliases.aliases[symbol.to_s]
	end

	##
	#
	# Extension registration
	#
	##

	#
	# Loads the client half of the supplied extension and initializes it as a
	# registered extension that can be reached through client.ext.[extension].
	#
	def add_extension(name)
		# Check to see if this extension has already been loaded.
		if ((klass = self.class.check_ext_hash(name.downcase)) == nil)
			old = Rex::Post::Meterpreter::Extensions.constants
			require("rex/post/meterpreter/extensions/#{name.downcase}/#{name.downcase}")
			new = Rex::Post::Meterpreter::Extensions.constants

			# No new constants added?
			if ((diff = new - old).empty?)
				diff = [ name.capitalize ]
			end

			klass = Rex::Post::Meterpreter::Extensions.const_get(diff[0]).const_get(diff[0])

			# Save the module name to class association now that the code is
			# loaded.
			self.class.set_ext_hash(name.downcase, klass)
		end

		# Create a new instance of the extension
		inst = klass.new(self)

		self.ext.aliases[inst.name] = inst

		return true
	end

	#
	# Deregisters an extension alias of the supplied name.
	#
	def deregister_extension(name)
		self.ext.aliases.delete(name)
	end

	#
	# Enumerates all of the loaded extensions.
	#
	def each_extension(&block)
		self.ext.aliases.each(block)
	end

	#
	# Registers an aliased extension that can be referenced through
	# client.name.
	#
	def register_extension_alias(name, ext)
		self.ext_aliases.aliases[name] = ext
	end

	#
	# Registers zero or more aliases that are provided in an array.
	#
	def register_extension_aliases(aliases)
		aliases.each { |a|
			register_extension_alias(a['name'], a['ext'])
		}
	end

	#
	# Deregisters a previously registered extension alias.
	#
	def deregister_extension_alias(name)
		self.ext_aliases.aliases.delete(name)
	end

	#
	# Dumps the extension tree.
	#
	def dump_extension_tree()
		items = []
		items.concat(self.ext.dump_alias_tree('client.ext'))
		items.concat(self.ext_aliases.dump_alias_tree('client'))

		return items.sort
	end

	#
	# Encodes (or not) a UTF-8 string
	#
	def unicode_filter_encode(str)
		self.encode_unicode ? Rex::Text.unicode_filter_encode(str) : str
	end

	#
	# Decodes (or not) a UTF-8 string
	#
	def unicode_filter_decode(str)
		self.encode_unicode ? Rex::Text.unicode_filter_decode(str) : str
	end

	#
	# The extension alias under which all extensions can be accessed by name.
	# For example:
	#
	#    client.ext.stdapi
	#
	#
	attr_reader   :ext
	#
	# The socket the client is communicating over.
	#
	attr_reader   :sock
	#
	# The timeout value to use when waiting for responses.
	#
	attr_accessor :response_timeout
	#
	# Whether to send pings every so often to determine liveness.
	#
	attr_accessor :send_keepalives
	#
	# Whether this session is alive.  If the socket is disconnected or broken,
	# this will be false
	#
	attr_accessor :alive
	#
	# The unique target identifier for this payload
	#
	attr_accessor :target_id
	#
	# The libraries available to this meterpreter server
	#
	attr_accessor :capabilities
	#
	# The Connection ID
	#
	attr_accessor :conn_id
	#
	# The Connect URL
	#
	attr_accessor :url
	#
	# Use SSL (HTTPS)
	#
	attr_accessor :ssl
	#
	# The Session Expiration Timeout
	#
	attr_accessor :expiration
	#
	# The Communication Timeout
	#
	attr_accessor :comm_timeout
	#
	# The Passive Dispatcher
	#
	attr_accessor :passive_dispatcher
	#
	# Flag indicating whether to hex-encode UTF-8 file names and other strings
	#
	attr_accessor :encode_unicode

protected
	attr_accessor :parser, :ext_aliases # :nodoc:
	attr_writer   :ext, :sock # :nodoc:
end

end; end; end