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#--
# CyborgHood, a distributed system management software.
# Copyright (c) 2009-2010 Marc Dequènes (Duck) <Duck@DuckCorp.org>
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program. If not, see <http://www.gnu.org/licenses/>.
#++

require 'yaml'
require 'cyborghood/cyborg/session'

# Note: Event machine core is mono-thread, so this code is not threadsafe.
# Only long tasks will be run in threads, which do not care about all this.

module CyborgHood

module BotProtocol
VERSION = "0.1"

# TODO:
# - check for request/reply couples (reply to wrong of non-existent request)
# - check for negociation wip/done

def initialize(conversation)
@conversation = conversation

@negociation_received = false
@negociation_sent = false
@negociation_ok = false
end

def negociation_ok?
@negociation_ok
end

def process_received_message(message)
method = "receive_" + message.action_code.downcase.tr(" ", "_")
if respond_to? method
send(method, message)
else
send_error_protocol("unknown action")
end
end

def receive_announce_helo(message)
unless message.conv_thread.id == 0
return send_quit_decline "bad negociation"
end
unless message.parameters[:bot_name] =~ Conversation::BOT_ID_PATTERN
return send_quit_decline "bad bot name"
end
unless message.parameters[:protocol_version] == VERSION
return send_quit_decline "protocol version does not match"
end
@negociation_received = true
@conversation.set_peer_info(message.parameters[:bot_name], message.parameters[:capabilities])

if @negociation_sent
send_announce_ok(message)
@negociation_ok = true
else
send_announce_helo(message)
@negociation_sent = true
end
end

def receive_announce_ok(message)
unless @negociation_sent and @negociation_received
send_quit_decline "bad negociation"
end
@negociation_ok = true
end

def send_announce_helo(recv_message = nil)
action_code = "ANNOUNCE HELO"
message = (recv_message.nil? ? @conversation.thread('system').new_message(action_code) :
recv_message.create_reply(action_code))
message.send
end

def send_announce_ok(recv_message)
recv_message.create_reply("ANNOUNCE OK").send
end

def send_error_protocol(message = nil)
# message can be nil if nothing could be parsed (or we may close the conversation, dunno)
# TODO
# @conversation.set_error_status
# @conversation.send_peer("ERROR PROTO", { :error => msg || "" })
end

def send_reply_ack(recv_message)
recv_message.create_reply("REPLY ACK").send
end

def send_quit_decline(recv_message, reason)
recv_message.create_reply("QUIT LEAVING", { :reason => reason }).send
end

def send_quit_leaving
conversation.thread('system').new_message("QUIT LEAVING").send
end
end

class ConversationThread
attr_reader :conversation, :name, :id, :session

def initialized(conversation, id, name)
@conversation = conversation
@name = name
@id = id

@session = Session.new
@next_action_id = 0
end

def new_message(action_code, parameters = nil, action_id = nil)
Message.new(self, action_code, parameters)
end

def next_action_id
id = @next_action_id
@next_action_id +=1
id
end

def close
@session.clear
# TODO: enforce destruction ???
end
end

class Message
private_class_method :new

attr_reader :conv_thread, :action_code, :action_parameters, :action_id

def initialized(conv_thread, action_code, action_parameters = nil, action_id = nil)
@conv_thread = conv_thread
@action_code = action_code
@action_parameters = action_parameters
@action_id = action_id
end

def new?
@action_id.nil?
end

def send
raise CyberError.new(:unrecoverable, "bot/conversation", "Not sending twice the same message") unless self.new?
@action_id = @conv_thread.next_action_id
@conv_thread.conversation.send_message(self)
end

def create_reply(action_code, parameters)
raise CyberError.new(:unrecoverable, "bot/conversation", "Cannot reply to a newly created message") if self.new?
new(self, action_code, parameters)
end
end

class Conversation < EventMachine::Protocols::LineAndTextProtocol
private_class_method :new

# don't rely on EventMachine's default, it may change one day
MaxLineLength = 16*1024

EOD = "\033[0J"
BOT_ID_PATTERN = "[a-zA-Z0-9]+"
ACTION_WORD_PATTERN = "[a-zA-Z0-9]+"
ACTION_PATTERN = "^(#{BOT_ID_PATTERN})(\d{4})-(\d{4})([+]?) (#{ACTION_WORD_PATTERN}( #{ACTION_WORD_PATTERN})*)$"
MAXIMUM_ERROR_COUNT = 3
MAXIMUM_LINES = 1024

attr_reader :interface

def initialize(interface)
@interface = interface

super

@config = Config.instance

@receive_error_count = 0
@split_data_mode = false
@split_data_message = nil
@split_data = []

# associated conversation threads
@conv_threads = {}
# thread 0 is reserved
@next_thread_id = 0
@system_thread = self.thread('system')

# post-negociation peer info
@peer_id = nil
@peer_capabilities = []

@protocol = BotProtocol.new(self)
end

def clear_receive_info
@receive_error = false
@receive_fatal_error = false
end

def send_line(msg)
send_data "#{msg}\n"
logger.debug "Sent data [#{identifier}]: #{msg}"
end

def post_init
logger.debug "New conversation with #{identifier}"
end

def receive_line(data)
return if data.empty?

clear_receive_info

if data == EOD
logger.debug "Received EOD [#{identifier}]"
exit_split_mode
else
if @split_data_mode
logger.debug "Received data (split mode) [#{identifier}]: #{data}"

if @split_data.size > MAXIMUM_LINES
reply_fatal_error "overflow"
else
@split_data << data
end
else
logger.debug "Received data [#{identifier}]: #{data}"

if data =~ Regexp.new(ACTION_PATTERN)
conv_thread_id = $1
action_id = $2
flags = $3 || ""
action_code = $4

conv_thread = self.thread_by_id(conv_thread_id)
message = conv_thread.new_message(action_code, nil, action_id)

if flags.index '+'
enter_split_mode(message)
else
receive_message(message)
end
else
reply_syntax_error "bad action format"
end
end
end

send_reply

# TODO: properly QUIT
@error_count += 1 if @receive_error
if @error_count >= MAXIMUM_ERROR_COUNT
reply_fatal_error "too much errors, terminating"
end
close_connection_after_writing if @fatal_error
end

def receive_message(message)
logger.debug "Received message '#{action}' [#{identifier}]"

@protocol.process_received_message(message)
end

def receive_error(msg)
logger.error "Error [#{identifier}]: #{msg}"
end

def unbind
logger.debug "Conversation finished with #{identifier}"
@conv_threads.each_values {|s| s.close }
end

def set_peer_info(id, capabilities)
@peer_id = id
@peer_capabilities = capabilities || []
end

def set_error_status(fatal = false)
# fatal status is conservative, it cannot be canceled
@reveive_fatal_error = @reveive_fatal_error || fatal
@receive_error = true
end

def thread(name = 'default')
@conv_threads[name] || new_thread(name)
end

def thread_by_id(id)
name = @conv_threads_index[id]
name.nil? ? new_thread("noname/#{id}", id) : @conv_threads[name]
end

def send_message(message)
raise CyberError.new(:unrecoverable, "bot/conversation", "Cannot send message without action id") if message.action_id.nil?

send_line "#{@config.bot_id}-#{message.conv_thread.id}-#{message.action_id}" + (message.action_parameters.nil? : "" : "+") + " #{message.action_code}"
unless message.action_parameters.nil?
message.action_parameters.to_yaml.split.each {|l| send_line l }
send_line EOD
end

action_id
end

protected

def new_thread(name, id = nil)
id ||= @next_thread_id
th = ConversationThread.new(self, id, name)
@next_thread_id = [@next_thread_id, id + 1].max

@conv_threads[th.name] = th
# allow searching by id too
@conv_threads_index[th.id] = name
th
end

def reply_syntax_error(msg = nil)
logger.error "Protocol error [#{identifier}]: syntax error (#{msg})"
set_error_status

msg = "syntax error" + (msg ? ": " + msg : "")
@protocol.send_error_protocol(msg)
end

def reply_fatal_error(msg = nil)
logger.error "Protocol error [#{identifier}]: fatal error (#{msg})"
set_error_status(true)

msg = "fatal error" + (msg ? ": " + msg : "")
@protocol.send_error_protocol(msg)
end

def enter_split_mode(message)
if @split_data_mode
reply_fatal_error "already in split mode"
@split_data_mode = false
@split_data_message = nil
else
logger.debug "Protocol info [#{identifier}]: entered split mode for action '#{message.action_id}'"
@split_data_mode = true
@split_data_message = message
end
@split_data = []
end

def exit_split_mode
if @split_data_mode
logger.debug "Protocol info [#{identifier}]: quit split mode for action '#{@split_data_message.action_id}'"

parameters = YAML.parse(@split_data.join("\n"))
reply_syntax_error("bad parameters format") if parameters.nil?

message = @split_data_message.conv_thread.new_message(@split_data_message.action_code, parameters, @split_data_message.action_id)
receive_message(message)
else
reply_fatal_error "not in split mode"
end
@split_data_mode = false
@split_data_message = nil
@split_data = []
end
end

class ConversationUNIXSocket < Conversation
public_class_method :new

def identifier
"unix_socket/#{@signature}"
end
end
end
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