#!/usr/bin/env ruby
# Simple Ruby XML Socket Server
#
# This is a a simple socket server implementation in ruby
# to communicate with flash clients via Flash XML Sockets.
#
# The socket code is based on the tutorial
# "Sockets programming in Ruby"
# by M. Tim Jones (mtj@mtjones.com).
#
# Date:: Tue, 05 Mar 2008
# Author:: Sebastian Tschan, https://blueimp.net
# License:: GNU Affero General Public License
# Include socket library:
require 'socket'
# Include XML libraries:
require 'rexml/document'
require 'rexml/streamlistener'
# XML Stream Handler class used to parse chat messages:
class XMLStreamHandler
attr_reader :type,:chat_id,:user_id,:reg_id,:channel_id,:channel_ids
# Called when an opening tag (including attributes) is parsed:
def tag_start name, attrs
case name
when 'root'
# root messages are broadcast messages:
@type = :message
@chat_id = attrs['chatID']
@channel_id = attrs['channelID']
throw :break
when 'register'
# register messages are sent by chat clients:
@type = :register
@chat_id = attrs['chatID']
@user_id = attrs['userID']
@reg_id = attrs['regID']
throw :break
when 'authenticate'
# authenticate messages are sent by the chat server client:
@type = :authenticate
@chat_id = attrs['chatID']
@user_id = attrs['userID']
@reg_id = attrs['regID']
@channel_ids = Array::new
when 'channel'
# authenticate messages contain channel tags:
if @channel_ids
@channel_ids.push(attrs['id'])
else
throw :break
end
when 'policy-file-request'
# policy-file-requests are sent by flash clients for cross-domain authentication:
@type = :policy_file_request
throw :break
else
throw :break
end
end
# Called when a closing tag is parsed:
def tag_end name
if name == 'authenticate'
throw :break
end
end
def text text
# Called on text between tags
end
# Called when cdata is parsed:
alias cdata text
end
# Socket Server class:
class SocketServer
def initialize(config_file)
# List of configuration settings:
@config = Hash::new
# Initialize default settings:
initialize_default_properties
if config_file
# Load settings from configuration file:
load_properties_from_file(config_file)
end
# Sockets list:
@sockets = Array::new
# Clients list:
@clients = Hash::new
# Chats list, used to distinguish between different chat installations (contains channels list):
@chats = Hash::new
# Initialize server socket:
initialize_server_socket
if @server_socket
# Log server start (STDOUT.flush prevents output buffering):
puts "#{Time.now}\tServer started on Port #{@config[:server_port].to_s} ..."; STDOUT.flush
begin
# Start the server:
run
rescue SignalException
# Controlled stop:
ensure
for socket in @sockets
if socket != @server_socket
# Disconnect all clients:
handle_client_disconnection(socket, false)
end
end
@sockets = nil
@clients = nil
# Log server stop:
puts "#{Time.now}\tServer stopped."; STDOUT.flush
end
end
end
def run
# Endless loop:
while 1
# Blocking select call. The first three parameters are arrays of IO objects or nil.
# The last parameter is to set a timeout in seconds to force select to return
# if no event has occurred on any of the given IO object arrays.
res = select(@sockets, nil, nil, nil)
if res != nil then
# Iterate through the tagged read descriptors:
for socket in res[0]
# Received a connect to the server socket:
if socket == @server_socket then
accept_new_connection
else
# Received something on a client socket:
if socket.eof? then
# Handle client disconnection:
handle_client_disconnection(socket)
else
# Handle client input data:
handle_client_input(socket, socket.gets(@config[:eol]))
end
end
end
end
end
end
private
def initialize_default_properties
# Server address (empty = bind to all available interfaces):
@config[:server_address] = ''
# Server port:
@config[:server_port] = 1935
# Comma-separated list of clients allowed to broadcast (allows all if empty):
@config[:broadcast_clients] = ''
# Defines if broadcast is sent to broadcasting client:
@config[:broadcast_self] = false
# Maximum number of clients (0 allows an unlimited number of clients):
@config[:max_clients] = 0
# Comma-separated list of domains from which downloaded Flash clients are allowed to connect (* allows all domains):
@config[:allow_access_from] = '*'
# Defines the cross-domain-policy string sent to Flash clients as response to a policy-file-request:
@config[:cross_domain_policy] = '<cross-domain-policy><allow-access-from domain="'+@config[:allow_access_from]+'" to-ports="'+@config[:server_port].to_s+'"/></cross-domain-policy>'
# EOL (End Of Line) character used by Flash XML Socket communication (a null-byte):
@config[:eol] = "\0"
# Log level (0 logs only errors and server start/stop, 1 logs client connections, 2 logs all messages but no broadcast content, 3 logs everything):
@config[:log_level] = 0
end
def load_properties_from_file(config_file)
# Open the config file and go through each line:
File.open(config_file, 'r') do |file|
file.read.each_line do |line|
# Remove trailing whitespace from the line:
line.strip!
# Get the position of the first "=":
i = line.index('=')
# Check if line is not a comment and a valid property:
if (!line.empty? && line[0] != ?# && i > 0)
# Add the configuration option to the config hash:
key = line[0..i - 1].strip
value = line[i + 1..-1].strip
# Parse boolean values:
if value.eql?('false')
@config[key.to_sym] = false
elsif value.eql?('true')
@config[key.to_sym] = true
# Parse integer numbers:
elsif value.to_i.to_s.eql?(value)
@config[key.to_sym] = value.to_i
# Parse floating point numbers:
elsif value.to_f.to_s.eql?(value)
@config[key.to_sym] = value.to_f
# Parse string values:
else
@config[key.to_sym] = value
end
end
end
end
if @config[:eol].empty?
# Use default EOL if configuration option is empty:
@config[:eol] = $/
end
end
def initialize_server_socket
begin
# The server socket, allowing connections from any interface and bound to the given port number:
@server_socket = TCPServer.new(@config[:server_address], @config[:server_port].to_i)
# Enable reuse of the server address (e.g. for rapid restarts of the server):
@server_socket.setsockopt(Socket::SOL_SOCKET, Socket::SO_REUSEADDR, 1)
# Add the server socket to the sockets list:
@sockets.push(@server_socket)
rescue Exception => error
# Log initialization failure:
puts "#{Time.now}\tFailed to initialize Server on Port #{@config[:server_port].to_s}: #{error}."; STDOUT.flush
end
end
def accept_new_connection
begin
# Accept the client connection (non-blocking):
socket = @server_socket.accept_nonblock
# Retrieve IP and Port:
ip = socket.peeraddr[3]
port = socket.peeraddr[1]
# Check if we have reached the maximum number of connected clients (always accept the broadcast clients):
if @config[:max_clients].to_i == 0 || @clients.size < @config[:max_clients].to_i || !@config[:broadcast_clients].empty? && @config[:broadcast_clients].include?(ip)
# Add the accepted socket connection to the socket list:
@sockets.push(socket)
# Create a new Hash to store the client data:
client = Hash::new
client[:id] = "[#{ip}]:#{port}"
# Check if the client is allowed to broadcast:
if @config[:broadcast_clients].empty? || @config[:broadcast_clients].include?(ip)
client[:allowed_to_broadcast] = true
else
client[:allowed_to_broadcast] = false
end
# Add the client to the clients list:
@clients[socket] = client
if @config[:log_level].to_i > 0
# Log client connection and the number of connected clients:
puts "#{Time.now}\t#{client[:id]} Connects\t(#{@clients.size} connected)"; STDOUT.flush
end
else
# Close the socket connection:
socket.close
end
rescue
# Client disconnected before the address information (IP, Port) could be retrieved.
end
end
def handle_client_disconnection(client_socket, delete_socket=true)
# Retrieve the client ID for the current socket:
client_id = @clients[client_socket][:id]
begin
# Close the socket connection:
client_socket.close
rescue
# Rescue if closing the socket fails
end
if delete_socket
# Remove the socket from the sockets list:
@sockets.delete(client_socket)
end
# Remove the client ID from the clients list:
@clients.delete(client_socket)
if @config[:log_level].to_i > 0
# Log client disconnection and the number of connected clients:
puts "#{Time.now}\t#{client_id} Disconnects\t(#{@clients.size} connected)"; STDOUT.flush
end
end
def handle_client_input(client_socket, str)
# Create a new XML stream handler:
handler = XMLStreamHandler.new
begin
# As soon as the parser has found the relevant information it throws a :break symbol:
catch :break do
# Parse the given input string for XML messages:
REXML::Document.parse_stream(str, handler)
end
# The handler stores a type property to define the parsed XML message:
case handler.type
when :message
handle_broadcast_message(client_socket, handler.chat_id, handler.channel_id, str)
when :register
handle_client_registration(client_socket, handler.chat_id, handler.user_id, handler.reg_id)
when :authenticate
handle_client_authentication(client_socket, handler.chat_id, handler.user_id, handler.reg_id, handler.channel_ids)
when :policy_file_request
handle_policy_file_request(client_socket)
end
rescue Exception => error
# Rescue if parsing the client input fails and log the error message:
puts "#{Time.now}\t#{@clients[client_socket][:id]} Client Input Error:#{error.to_s.dump}"; STDOUT.flush
end
end
def handle_broadcast_message(client_socket, chat_id, channel_id, str)
# Check if the_client is allowed to broadcast:
if @clients[client_socket][:allowed_to_broadcast]
# Check if the chat and channel have been registered:
if @chats[chat_id] && (@chats[chat_id][channel_id] || @chats[chat_id]['ALL'])
# Go through the sockets list:
@sockets.each do |socket|
# Skip the server socket and skip the the client socket if broadcast is not to be sent to self:
if socket != @server_socket && (@config[:broadcast_self] || socket != client_socket)
# Only write to clients registered to the given channel or to the "ALL" channel:
if @chats[chat_id]['ALL']
reg_id = @chats[chat_id]['ALL'][@clients[socket][:user_id]]
end
if !reg_id && @chats[chat_id][channel_id]
reg_id = @chats[chat_id][channel_id][@clients[socket][:user_id]]
end
# Check if the reg_id stored for the given channel and user_id matches the clients reg_id:
if reg_id && reg_id.eql?(@clients[socket][:reg_id])
begin
# Write the broadcast message on the socket connection:
socket.write(str)
rescue
# Rescue if writing to the socket fails
end
end
end
end
end
if @config[:log_level].to_i > 2
# Log the message sent by the broadcast client:
puts "#{Time.now}\t#{@clients[client_socket][:id]} Chat:#{chat_id.to_s.dump} Channel:#{channel_id.to_s.dump} Message:#{str.to_s.dump}"; STDOUT.flush
elsif @config[:log_level].to_i > 1
# Log the message sent by the broadcast client:
puts "#{Time.now}\t#{@clients[client_socket][:id]} Chat:#{chat_id.to_s.dump} Channel:#{channel_id.to_s.dump} Message"; STDOUT.flush
end
end
end
def handle_client_registration(client_socket, chat_id, user_id, reg_id)
# Save the chat_id, use_id and reg_id as client properties:
@clients[client_socket][:chat_id] = chat_id
@clients[client_socket][:user_id] = user_id
@clients[client_socket][:reg_id] = reg_id
if @config[:log_level].to_i > 1
# Log the client registration:
puts "#{Time.now}\t#{@clients[client_socket][:id]} Chat:#{chat_id.to_s.dump} User:#{user_id.to_s.dump} Reg:#{reg_id.to_s.dump}"; STDOUT.flush
end
end
def handle_client_authentication(client_socket, chat_id, user_id, reg_id, channel_ids)
# Only the broadcast clients may send authentication messages:
if @clients[client_socket][:allowed_to_broadcast]
# Create a new chat item if not found for the given chat_id:
if !@chats[chat_id]
@chats[chat_id] = Hash.new
end
# Go through the list of channels for the given chat:
@chats[chat_id].each_key do |key|
# Delete all items for the given user on all channels of the given chat:
@chats[chat_id][key].delete(user_id)
# If the chat channel is empty, delete the channel item:
if @chats[chat_id][key].size == 0
@chats[chat_id].delete(key)
end
end
# Go through the list of authenticated channel_ids:
channel_ids.each do |channel_id|
# Create a new channel item if not found for the current channel_id (and the given chat_id):
if !@chats[chat_id][channel_id]
@chats[chat_id][channel_id] = Hash.new
end
# Add a user item of the given user_id with the given reg_id to the current channel:
@chats[chat_id][channel_id][user_id] = reg_id
end
if @config[:log_level].to_i > 1
# Log the client authentication:
puts "#{Time.now}\t#{@clients[client_socket][:id]} Chat:#{chat_id.to_s.dump} User:#{user_id.to_s.dump} Auth:#{reg_id.to_s.dump} Channels:#{channel_ids.join(',').dump}"; STDOUT.flush
end
end
end
def handle_policy_file_request(client_socket)
begin
# Write the cross-domain-policy to the Flash client:
client_socket.write(@config[:cross_domain_policy]+@config[:eol])
rescue
# Rescue if writing to the socket fails
end
if @config[:log_level].to_i > 1
# Log the policy-file-request:
puts "#{Time.now}\t#{@clients[client_socket][:id]} Policy-File-Request"; STDOUT.flush
end
end
end
# Start the socket server with the first command line argument as configuration file:
SocketServer.new($*[0])
