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require 'net/ssh/buffer'
require 'net/ssh/transport/constants'
require 'net/ssh/authentication/constants'
require 'net/ssh/connection/constants'
module Net
module SSH
# A specialization of Buffer that knows the format of certain common
# packet types. It auto-parses those packet types, and allows them to
# be accessed via the #[] accessor.
#
# data = some_channel_request_packet
# packet = Net::SSH::Packet.new(data)
#
# p packet.type #-> 98 (CHANNEL_REQUEST)
# p packet[:request]
# p packet[:want_reply]
#
# This is used exclusively internally by Net::SSH, and unless you're doing
# protocol-level manipulation or are extending Net::SSH in some way, you'll
# never need to use this class directly.
class Packet < Buffer
@@types = {}
# Register a new packet type that should be recognized and auto-parsed by
# Net::SSH::Packet. Note that any packet type that is not preregistered
# will not be autoparsed.
#
# The +pairs+ parameter must be either empty, or an array of two-element
# tuples, where the first element of each tuple is the name of the field,
# and the second is the type.
#
# register DISCONNECT, [:reason_code, :long], [:description, :string], [:language, :string]
def self.register(type, *pairs)
@@types[type] = pairs
end
include Connection::Constants
include Authentication::Constants
include Transport::Constants
#--
# These are the recognized packet types. All other packet types will be
# accepted, but not auto-parsed, requiring the client to parse the
# fields using the methods provided by Net::SSH::Buffer.
#++
register DISCONNECT, %i[reason_code long], %i[description string], %i[language string]
register IGNORE, %i[data string]
register UNIMPLEMENTED, %i[number long]
register DEBUG, %i[always_display bool], %i[message string], %i[language string]
register SERVICE_ACCEPT, %i[service_name string]
register USERAUTH_BANNER, %i[message string], %i[language string]
register USERAUTH_FAILURE, %i[authentications string], %i[partial_success bool]
register GLOBAL_REQUEST, %i[request_type string], %i[want_reply bool], %i[request_data buffer]
register CHANNEL_OPEN, %i[channel_type string], %i[remote_id long], %i[window_size long], %i[packet_size long]
register CHANNEL_OPEN_CONFIRMATION, %i[local_id long], %i[remote_id long], %i[window_size long], %i[packet_size long]
register CHANNEL_OPEN_FAILURE, %i[local_id long], %i[reason_code long], %i[description string], %i[language string]
register CHANNEL_WINDOW_ADJUST, %i[local_id long], %i[extra_bytes long]
register CHANNEL_DATA, %i[local_id long], %i[data string]
register CHANNEL_EXTENDED_DATA, %i[local_id long], %i[data_type long], %i[data string]
register CHANNEL_EOF, %i[local_id long]
register CHANNEL_CLOSE, %i[local_id long]
register CHANNEL_REQUEST, %i[local_id long], %i[request string], %i[want_reply bool], %i[request_data buffer]
register CHANNEL_SUCCESS, %i[local_id long]
register CHANNEL_FAILURE, %i[local_id long]
# The (integer) type of this packet.
attr_reader :type
# Create a new packet from the given payload. This will automatically
# parse the packet if it is one that has been previously registered with
# Packet.register; otherwise, the packet will need to be manually parsed
# using the methods provided in the Net::SSH::Buffer superclass.
def initialize(payload)
@named_elements = {}
super
@type = read_byte
instantiate!
end
# Access one of the auto-parsed fields by name. Raises an error if no
# element by the given name exists.
def [](name)
name = name.to_sym
raise ArgumentError, "no such element #{name}" unless @named_elements.key?(name)
@named_elements[name]
end
private
# Parse the packet's contents and assign the named elements, as described
# by the registered format for the packet.
def instantiate!
(@@types[type] || []).each do |name, datatype|
@named_elements[name.to_sym] = if datatype == :buffer
remainder_as_buffer
else
send("read_#{datatype}")
end
end
end
end
end
end
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