#!/usr/bin/ruby
#    This file is part of Metasm, the Ruby assembly manipulation suite
#    Copyright (C) 2006-2009 Yoann GUILLOT
#
#    Licence is LGPL, see LICENCE in the top-level directory


# this is a TCP proxy which dumps the transmitted data in hex on stdout
# usage: tcp_proxy <lhost> <lport> <rhost> <rport> [<timeout_s>]

require 'socket'
require File.join(File.dirname(__FILE__), 'hexdump')

def bouncepkt(clt, srv, timeout=nil)
	s2c = ''
	c2s = ''
	loop do
		break if not IO.select([clt, srv], nil, nil, timeout)

		while srv and s2c.length < 1024*16 and IO.select([srv], nil, nil, 0)
			str = (srv.read(1) rescue nil)
			if not str or str.empty?
				srv = false
			else
				s2c << str
			end
		end

		while clt and c2s.length < 1024*16 and IO.select([clt], nil, nil, 0)
			str = (clt.read(1) rescue nil)
			if not str or str.empty?
				clt = false
			else
				c2s << str
			end
		end

		if clt and s2c.length > 0 and IO.select(nil, [clt], nil, 0)
			puts Time.now.strftime('s -> c  %H:%M:%S')
			s2c.hexdump(:fmt => ['c', 'a'])
			clt.write s2c
			s2c.replace ''
		end

		if srv and c2s.length > 0 and IO.select(nil, [srv], nil, 0)
			puts Time.now.strftime('c -> s  %H:%M:%S')
			c2s.hexdump(:fmt => ['c', 'a'])
			srv.write c2s
			c2s.replace ''
		end
		break if not clt or not srv
	end
end


if $0 == __FILE__
if ARGV.length < 4
	abort "usage: bnc <lhost> <lport> <rhost> <rport> [<timeout_s>]"
end

lhost = ARGV.shift
lport = Integer(ARGV.shift)
rhost = ARGV.shift
rport = Integer(ARGV.shift)
timeout = Float(ARGV.shift) if not ARGV.empty?

s = TCPServer.new(lhost, lport)

loop do
	puts "waiting..."
	a = s.accept
	puts "incoming connection"
	c = TCPSocket.new(rhost, rport)
	
	begin
		bouncepkt(a, c, timeout)
	rescue SystemCallError
	end

	puts "connection closed"
	a.close
	c.close
end
end