# Cafe Server v0.2
# Ryan Verner <xfesty@computeraddictions.com.au>
# 19 NOV 2002
#
# Thanks to Asx / irc.freenode.net for much help and sample
# code.
#
# TODO:
# - encryption, hash possibly based on IP of client machine
# with a crypt understood by this server
# - verifying that the username reported to this is in fact
# valid to a recent login (samba logs?)

# DATA WATCHING ON NAT....
# WHEN CLIENT QUITS MANUALLY, NAT IS DISABLED FOR THAT IP

require 'socket'
require 'mysql'
Thread.abort_on_exception = true

class ClientQuitError < RuntimeError; end

port = ARGV.shift || 9999  
host = ARGV.shift || '10.12.0.1'

m = Mysql.new('localhost', '*****', '********', '*****')

server = TCPServer.open(host, port)

port = server.addr[1]
addrs = server.addr[2..-1].uniq()

puts %!*** Listening on #{addrs.collect{|a|"#{a}:#{port}"}.join(' ')}!

def does_user_exist(m, x)
  res = m.query("select * from users where username='" + x + "'")  
  fields = res.fetch_fields.collect do |f| f.name end
  x_user = nil
  res.each do |row|
   x_user = row.join("\t")
  end
  return x_user
end


def get_remaining(m, x, table)
  res = m.query("select x_remaining_" + table + " from users where username='" + x + "'")
  fields = res.fetch_fields.collect do |f| f.name end
  x_time = nil
  res.each do |row|
   x_time = row.join("\t")
  end
  return x_time
end

def unlim(m, x)
  res = m.query("select x_unlim_acct from users where username='" + x + "'")
  fields = res.fetch_fields.collect do |f| f.name end
  x_unlim = nil
  res.each do |row|
   x_unlim = row.join("\t")
  end
  return x_unlim
end

def subtract(var, amount)
  return (var.to_i - amount).to_s
end

def update_newinfo(m, x, table, user)
  m.query("update users set x_remaining_" + table + "='" + x + "'" + " where username='" + user + "'")
end

def delete_user(m, user)
  m.query("delete from users where username='" + user + "'")
end
 
def nat_enable(ip)
 puts "*** Adding NAT iptables line for " + ip
 system("iptables -t nat -D POSTROUTING -s " + ip + " -o eth0 -j MASQUERADE")
 system("iptables -t nat -A POSTROUTING -s " + ip + " -o eth0 -j MASQUERADE")
end

def nat_disable(ip)
 puts "*** Removing NAT iptables line for " + ip
 system("iptables -t nat -D POSTROUTING -s " + ip + " -o eth0 -j MASQUERADE")
end

loop do
  socket = server.accept()

  Thread.start do # one thread per client
    s = socket

    port = s.peeraddr[1]
    name = s.peeraddr[2]
    addr = s.peeraddr[3]

    puts "*** Connection from #{name}:#{port}"

    nat_enable(name)

    begin

      while line = s.gets() # read a line at a time
       raise ClientQuitError if line =~ /^die\r?$/ 

       if does_user_exist(m, line) != nil # skip main stuff if user doesnt exist

        if unlim(m, line) != "1" # skip main stuff if unlimited account
 
         remaining_time = get_remaining(m, line, "time")
         if remaining_time != nil
          s.send(remaining_time + "\n", 0)
         end
 
         remaining_data = get_remaining(m, line, "data") 
         if remaining_data != nil
          s.send(remaining_data + "\n", 0)
         end
     
        puts "#{addr} [#{Time.now}]: #{line.chop} (#{remaining_time} mins, #{remaining_data} mb left)"

        new_time = subtract(remaining_time, 1)
        new_data = subtract(remaining_data, 0.5)

        update_newinfo(m, new_time, "time", line)
        #update_newinfo(m, new_data, "data", line)

        if new_time < "0"
         delete_user(m, line)
         raise ClientQuitError
        end

        if new_data < "0"
         delete_user(m, line)
         raise ClientQuitError
        end

      end
     end
    end

    rescue ClientQuitError
      puts "*** #{name}:#{port} Disconnected at [#{Time.now}]"
      nat_disable(name)

    ensure
      s.close() # close socket on error
    end

  end

end