Class: Rex::Proto::RFB::Client

Inherits:
Object
  • Object
show all
Defined in:
lib/rex/proto/rfb/client.rb

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(sock, opts = {}) ⇒ Client

Returns a new instance of Client.



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# File 'lib/rex/proto/rfb/client.rb', line 24

def initialize(sock, opts = {})
	@sock = sock
	@opts = opts

	@banner = nil
	@majver = MajorVersion
	@minver = -1
	@auth_types = []
end

Instance Attribute Details

#auth_types ⇒ Object (readonly)

Returns the value of attribute auth_types.



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# File 'lib/rex/proto/rfb/client.rb', line 201

def auth_types
  @auth_types
end

#error ⇒ Object (readonly)

Returns the value of attribute error.



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# File 'lib/rex/proto/rfb/client.rb', line 201

def error
  @error
end

#majver ⇒ Object (readonly)

Returns the value of attribute majver.



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# File 'lib/rex/proto/rfb/client.rb', line 201

def majver
  @majver
end

#minver ⇒ Object (readonly)

Returns the value of attribute minver.



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# File 'lib/rex/proto/rfb/client.rb', line 201

def minver
  @minver
end

#view_only ⇒ Object (readonly)

Returns the value of attribute view_only.



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# File 'lib/rex/proto/rfb/client.rb', line 202

def view_only
  @view_only
end

Instance Method Details

#authenticate(password = nil) ⇒ Object 



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# File 'lib/rex/proto/rfb/client.rb', line 87

def authenticate(password = nil)
	type = negotiate_authentication
	return false if not type

	# Authenticate.
	case type
	when AuthType::None
		# Nothing here.

	when AuthType::VNC
		return false if not negotiate_vnc_auth(password)

	end

	# Handle reading the security result message
	result = @sock.get_once(4)
	if not result
		@error = "Unable to read auth result"
		return false
	end

	result = result.unpack('N').first
	case result
	when 0
		return true

	when 1
		if @minver >= 8
			msg = read_error_message
			@error = "Authentication failed: #{msg}"
		else
			@error = "Authentication failed"
		end
	when 2
		@error = "Too many authentication attempts"
	else
		@error = "Unknown authentication result: #{result}"
	end

	false
end

#connect(password = nil) ⇒ Object 



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# File 'lib/rex/proto/rfb/client.rb', line 72

def connect(password = nil)
	return false if not handshake
	return false if not authenticate(password)
	return false if not send_client_init
	true
end

#handshake ⇒ Object 



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# File 'lib/rex/proto/rfb/client.rb', line 42

def handshake
	@banner = @sock.get_once(12)
	if not @banner
		@error = "Unable to obtain banner from server"
		return false
	end

	# RFB Protocol Version 3.3 (1998-01)
	# RFB Protocol Version 3.7 (2003-08)
	# RFB Protocol Version 3.8 (2007-06)

	if @banner =~ /RFB ([0-9]{3})\.([0-9]{3})/
		maj = $1.to_i
		if maj != MajorVersion
			@error = "Invalid major version number: #{maj}"
			return false
		end
	else
		@error = "Invalid RFB banner: #{@banner}"
		return false
	end

	@minver = $2.to_i

	our_ver = "RFB %03d.%03d\n" % [MajorVersion, @minver]
	@sock.put(our_ver)

	true
end

#negotiate_authentication ⇒ Object 



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# File 'lib/rex/proto/rfb/client.rb', line 129

def negotiate_authentication
	# Authentication type negotiation is protocol version specific.
	if @minver < 7
		buf = @sock.get_once(4)
		if not buf
			@error = "Unable to obtain requested authentication method"
			return nil
		end
		@auth_types = buf.unpack('N')
		if not @auth_types or @auth_types.first == 0
			msg = read_error_message
			@error = "No authentication types available: #{msg}"
			return nil
		end
	else
		buf = @sock.get_once(1)
		if not buf
			@error = "Unable to obtain supported authentication method count"
			return nil
		end

		# first byte is number of security types
		num_types = buf.unpack("C").first
		if (num_types == 0)
			msg = read_error_message
			@error = "No authentication types available: #{msg}"
			return nil
		end

		buf = @sock.get_once(num_types)
		if not buf or buf.length != num_types
			@error = "Unable to read authentication types"
			return nil
		end

		@auth_types = buf.unpack("C*")
	end

	if not @auth_types or @auth_types.length < 1
		@error = "No authentication types found"
		return nil
	end

	# Select the one we prefer
	selected = nil
	selected ||= AuthType::None if @opts[:allow_none] and @auth_types.include? AuthType::None
	selected ||= AuthType::VNC if @auth_types.include? AuthType::VNC

	if not selected
		@error = "No supported authentication method found."
		return nil
	end

	# For 3.7 and later, clients must state which security-type to use
	@sock.put([selected].pack('C')) if @minver >= 7

	selected
end

#negotiate_vnc_auth(password = nil) ⇒ Object 



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# File 'lib/rex/proto/rfb/client.rb', line 188

def negotiate_vnc_auth(password = nil)
	challenge = @sock.get_once(16)
	if not challenge or challenge.length != 16
		@error = "Unable to obtain VNC challenge"
		return false
	end

	response = Cipher.encrypt(challenge, password)
	@sock.put(response)

	true
end

#read_error_message ⇒ Object 



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# File 'lib/rex/proto/rfb/client.rb', line 34

def read_error_message
	len = @sock.get_once(4)
	return 'Unknown error' if not len or len.length != 4

	len = len.unpack("N").first
	@sock.get_once(len)
end

#send_client_init ⇒ Object 



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# File 'lib/rex/proto/rfb/client.rb', line 79

def send_client_init
	if @opts[:exclusive]
		@sock.put("\x00") # do share.
	else
		@sock.put("\x01") # do share.
	end
end