import socket, random

def s5b_prepare():
	s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
	
	port = None
	while True:
		port = random.randint(10000,2**16-1)
		try:	
			s.bind(('', port))
			s.listen(1)
			break
		except socket.error:
			pass
		
	return (s,port)

def s5b_write_file(s,fd,size):
	s.settimeout(20)
	conn, addr = s.accept()
	data = conn.recv(3)

	assert data[0]=='\x05' #SOCKS version not 5
	assert data[1]=='\x01' #not a connect command
	assert data[2]=='\x00' #does not support other connection method

	#send VER=5 METHOD=NO_AUTH
	conn.sendall('\x05\x00')

	data = conn.recv(47)

	assert data[0]=='\x05' # SOCKS version not 5
	assert data[1]=='\x01' # not a connect command
	# data[2] is reserved
	assert data[3]=='\x03' # addr type is name
	assert data[4]=='('
	name = data[5:45]
	assert data[45]=='\x00'
	assert data[46]=='\x00'

	#ACK
	conn.sendall('\x05\x00\x00'+'\x03('+name+'\x00\x00')
	#send file
	data = fd.read(min(size,1024))	
	size -= len(data)
	while data!='':
		conn.sendall(data)		
		data = fd.read(min(size,1024))
		size -= len(data)

	conn.close()
	fd.close()