#!/usr/bin/python3
#
import socket
import struct
import logging
import time
import enum
import select
import os
#
import accelerated_functions
#
class ProtocolException(Exception):
    pass
#
class ProtocolHelper():
	def __init__(self):
		self._buffer = b''
	#
	def set_buffer(self, data):
		"""
		Set the buffer contents to the data that you wish to send.
		"""
		#
		self._buffer = data
	#
	def get_buffer(self):
		return self._buffer
	#
	def recv(self, socket, num_bytes):
		"""
		Try to fill up the buffer to a max of 'num_bytes'. If the buffer is filled,
		return True, otherwise return False.
		"""
		#
		data = socket.recv(num_bytes-len(self._buffer))
		#
		if len(data) == 0:
			raise ProtocolException('The socket was closed.')
		#
		self._buffer += data
		if len(self._buffer) == num_bytes:
			return True
		#
		return False
	#
	def send(self, socket):
		"""
		Try to send the remainder of the buffer. If the entire buffer has been sent,
		return True, otherwise return False.
		"""
		#
		n = socket.send(self._buffer)
		self._buffer = self._buffer[n:]
		if len(self._buffer) == 0:
			return True
		#
		return False
	#
#
class Protocol():
	def _run_iteration(self):
		"""
		This function should be overridden. It runs a single iteration of the protocol.
		"""
		#
		pass
	#
	def run(self):
		while True:
			finished = self._run_iteration()
			#
			if finished:
				# protocol is done
				return True
			#
		#
	#
	def get_desc(self):
		"""
		This function can be overridden.
		"""
		#
		return None
	#
#
class FakeProxyProtocol(Protocol):
	def __init__(self, socket, addr_port):
		self.socket = socket
		self.addr_port = addr_port
		#
		self.states = enum.Enum('PROXY_STATES', 'READY_TO_BEGIN CONNECTING_TO_PROXY DONE')
		self.state = self.states.READY_TO_BEGIN
		#
		self.protocol_helper = None
	#
	def _run_iteration(self):
		if self.state is self.states.READY_TO_BEGIN:
			self.protocol_helper = ProtocolHelper()
			host, port = self.addr_port
			addr = socket.inet_aton(host)[::-1]
			self.protocol_helper.set_buffer(addr+struct.pack('!H', port))
			self.state = self.states.CONNECTING_TO_PROXY
		#
		if self.state is self.states.CONNECTING_TO_PROXY:
			if self.protocol_helper.send(self.socket):
				self.protocol_helper = ProtocolHelper()
				self.state = self.states.DONE
			#
		#
		if self.state is self.states.DONE:
			return True
		#
		return False
	#
#
class ChainedProtocol(Protocol):
	def __init__(self, protocols):
		self.protocols = protocols
		self.current_protocol = 0
		#
		self.states = enum.Enum('CHAIN_STATES', 'READY_TO_BEGIN RUNNING DONE')
		self.state = self.states.READY_TO_BEGIN
	#
	def _run_iteration(self):
		if self.state is self.states.READY_TO_BEGIN:
			self.state = self.states.RUNNING
		#
		if self.state is self.states.RUNNING:
			if self.protocols[self.current_protocol] is None or self.protocols[self.current_protocol].run():
				self.current_protocol += 1
			#
			if self.current_protocol >= len(self.protocols):
				self.state = self.states.DONE
			#
		#
		if self.state is self.states.DONE:
			return True
		#
		return False
	#
#
class Socks4Protocol(Protocol):
	def __init__(self, socket, addr_port, username=None):
		self.socket = socket
		self.addr_port = addr_port
		self.username = username
		#
		self.states = enum.Enum('SOCKS_4_STATES', 'READY_TO_BEGIN CONNECTING_TO_PROXY WAITING_FOR_PROXY DONE')
		self.state = self.states.READY_TO_BEGIN
		#
		self.protocol_helper = None
	#
	def _run_iteration(self):
		if self.state is self.states.READY_TO_BEGIN:
			self.protocol_helper = ProtocolHelper()
			self.protocol_helper.set_buffer(self.socks_cmd(self.addr_port, self.username))
			self.state = self.states.CONNECTING_TO_PROXY
		#
		if self.state is self.states.CONNECTING_TO_PROXY:
			if self.protocol_helper.send(self.socket):
				self.protocol_helper = ProtocolHelper()
				self.state = self.states.WAITING_FOR_PROXY
				#logging.debug('Waiting for reply from proxy')
			#
		#
		if self.state is self.states.WAITING_FOR_PROXY:
			response_size = 8
			if self.protocol_helper.recv(self.socket, response_size):
				response = self.protocol_helper.get_buffer()
				if response[1] != 0x5a:
					raise ProtocolException('Could not connect to SOCKS proxy, msg: %x'%(response[1],))
				#
				self.state = self.states.DONE
			#
		#
		if self.state is self.states.DONE:
			return True
		#
		return False
	#
	def socks_cmd(self, addr_port, username=None):
		socks_version = 4
		command = 1
		dnsname = b''
		host, port = addr_port
		#
		try:
			username = bytes(username, 'utf8')
		except TypeError:
			pass
		#
		if username is None:
			username = b''
		elif b'\x00' in username:
			raise ProtocolException('Username cannot contain a NUL character.')
		#
		username = username+b'\x00'
		#
		try:
			addr = socket.inet_aton(host)
		except socket.error:
			addr = b'\x00\x00\x00\x01'
			dnsname = bytes(host, 'utf8')+b'\x00'
		#
		return struct.pack('!BBH', socks_version, command, port) + addr + username + dnsname
	#
#
class PushDataProtocol(Protocol):
	def __init__(self, socket, total_bytes, send_buffer_len=None, use_acceleration=None, push_start_cb=None, push_done_cb=None):
		if send_buffer_len is None:
			send_buffer_len = 1024*512
		#
		if use_acceleration is None:
			use_acceleration = True
		#
		self.socket = socket
		self.total_bytes = total_bytes
		self.use_acceleration = use_acceleration
		self.push_start_cb = push_start_cb
		self.push_done_cb = push_done_cb
		#
		self.states = enum.Enum('PUSH_DATA_STATES', 'READY_TO_BEGIN SEND_INFO START_CALLBACK PUSH_DATA RECV_CONFIRMATION DONE_CALLBACK DONE')
		self.state = self.states.READY_TO_BEGIN
		#
		self.byte_buffer = os.urandom(send_buffer_len)
		self.bytes_written = 0
		self.time_started_push = None
		self.protocol_helper = None
	#
	def _run_iteration(self):
		if self.state is self.states.READY_TO_BEGIN:
			info = self.total_bytes.to_bytes(8, byteorder='big', signed=False)
			info += len(self.byte_buffer).to_bytes(8, byteorder='big', signed=False)
			self.protocol_helper = ProtocolHelper()
			self.protocol_helper.set_buffer(info)
			self.state = self.states.SEND_INFO
		#
		if self.state is self.states.SEND_INFO:
			if self.protocol_helper.send(self.socket):
				self.state = self.states.START_CALLBACK
			#
		#
		if self.state is self.states.START_CALLBACK:
			if self.push_start_cb is not None:
				self.push_start_cb()
			#
			self.state = self.states.PUSH_DATA
			self.time_started_push = time.time()
		#
		if self.state is self.states.PUSH_DATA:
			if self.use_acceleration:
				ret_val = accelerated_functions.push_data(self.socket.fileno(), self.total_bytes, self.byte_buffer)
				if ret_val < 0:
					raise ProtocolException('Error while pushing data.')
				#
				self.bytes_written = self.total_bytes
			else:
				bytes_remaining = self.total_bytes-self.bytes_written
				data_size = min(len(self.byte_buffer), bytes_remaining)
				if data_size != len(self.byte_buffer):
					data = self.byte_buffer[:data_size]
				else:
					data = self.byte_buffer
					# don't make a copy of the byte string each time if we don't need to
				#
				n = self.socket.send(data)
				self.bytes_written += n
			#
			if self.bytes_written == self.total_bytes:
				# finished sending the data
				logging.debug('Finished sending the data (%d bytes).', self.bytes_written)
				self.protocol_helper = ProtocolHelper()
				self.state = self.states.RECV_CONFIRMATION
			#
		#
		if self.state is self.states.RECV_CONFIRMATION:
			response_size = 8
			if self.protocol_helper.recv(self.socket, response_size):
				response = self.protocol_helper.get_buffer()
				if response != b'RECEIVED':
					raise ProtocolException('Did not receive the expected message: {}'.format(response))
				#
				self.state = self.states.DONE_CALLBACK
			#
		#
		if self.state is self.states.DONE_CALLBACK:
			if self.push_done_cb is not None:
				self.push_done_cb()
			#
			self.state = self.states.DONE
		#
		if self.state is self.states.DONE:
			return True
		#
		return False
	#
#
class PullDataProtocol(Protocol):
	def __init__(self, socket, use_acceleration=None):
		if use_acceleration is None:
			use_acceleration = True
		#
		self.socket = socket
		self.use_acceleration = use_acceleration
		#
		self.states = enum.Enum('PULL_DATA_STATES', 'READY_TO_BEGIN RECV_INFO PULL_DATA SEND_CONFIRMATION DONE')
		self.state = self.states.READY_TO_BEGIN
		#
		self.data_size = None
		self.recv_buffer_len = None
		self.bytes_read = 0
		self.protocol_helper = None
		self.time_of_first_byte = None
		self.time_of_last_byte = None
		#self.byte_counter = None
		#self.byte_counter_start_time = None
		self.deltas = None
	#
	def _run_iteration(self):
		if self.state is self.states.READY_TO_BEGIN:
			self.protocol_helper = ProtocolHelper()
			self.state = self.states.RECV_INFO
		#
		if self.state is self.states.RECV_INFO:
			info_size = 16
			if self.protocol_helper.recv(self.socket, info_size):
				response = self.protocol_helper.get_buffer()
				self.data_size = int.from_bytes(response[0:8], byteorder='big', signed=False)
				self.recv_buffer_len = int.from_bytes(response[8:16], byteorder='big', signed=False)
				assert(self.recv_buffer_len <= 10*1024*1024)
				# don't use a buffer size larget than 10 MiB to avoid using up all memory
				self.state = self.states.PULL_DATA
			#
		#
		if self.state is self.states.PULL_DATA:
			if self.use_acceleration:
				#(ret_val, time_of_first_byte, time_of_last_byte, byte_counter, byte_counter_start_time) = accelerated_functions.pull_data(self.socket.fileno(), self.data_size, self.recv_buffer_len)
				(ret_val, time_of_first_byte, time_of_last_byte, deltas) = accelerated_functions.pull_data(self.socket.fileno(), self.data_size, self.recv_buffer_len)
				if ret_val < 0:
					raise ProtocolException('Error while pulling data.')
				#
				#if sum(byte_counter) != self.data_size:
				if sum(deltas['bytes']) != self.data_size:
					logging.warning('Lost some history data ({} != {}).'.format(sum(deltas['bytes']), self.data_size))
				#
				self.bytes_read = self.data_size
				self.time_of_first_byte = time_of_first_byte
				self.time_of_last_byte = time_of_last_byte
				#self.byte_counter = byte_counter
				#self.byte_counter_start_time = byte_counter_start_time
				self.deltas = deltas
			else:
				bytes_remaining = self.data_size-self.bytes_read
				block_size = min(self.recv_buffer_len, bytes_remaining)
				#
				data = self.socket.recv(block_size)
				#
				if len(data) == 0:
					raise ProtocolException('The socket was closed.')
				#
				self.bytes_read += len(data)
				#
				if self.bytes_read != 0 and self.time_of_first_byte is None:
					self.time_of_first_byte = time.time()
				#
				if self.bytes_read == self.data_size and self.time_of_last_byte is None:
					self.time_of_last_byte = time.time()
				#
			#
			if self.bytes_read == self.data_size:
				# finished receiving the data
				logging.debug('Finished receiving the data.')
				self.protocol_helper = ProtocolHelper()
				self.protocol_helper.set_buffer(b'RECEIVED')
				self.state = self.states.SEND_CONFIRMATION
			#
		#
		if self.state is self.states.SEND_CONFIRMATION:
			if self.protocol_helper.send(self.socket):
				self.state = self.states.DONE
			#
		#
		if self.state is self.states.DONE:
			return True
		#
		return False
	#
	def calc_transfer_rate(self):
		""" Returns bytes/s. """
		assert self.data_size is not None and self.time_of_first_byte is not None and self.time_of_last_byte is not None
		try:
			return self.data_size/(self.time_of_last_byte-self.time_of_first_byte)
		except ZeroDivisionError:
			return float('nan')
		#
	#
#
class SendDataProtocol(Protocol):
	def __init__(self, socket, data):
		self.socket = socket
		self.send_data = data
		#
		self.states = enum.Enum('SEND_DATA_STATES', 'READY_TO_BEGIN SEND_INFO SEND_DATA RECV_CONFIRMATION DONE')
		self.state = self.states.READY_TO_BEGIN
		#
		self.protocol_helper = None
	#
	def _run_iteration(self):
		if self.state is self.states.READY_TO_BEGIN:
			info_size = 20
			info = len(self.send_data).to_bytes(info_size, byteorder='big', signed=False)
			self.protocol_helper = ProtocolHelper()
			self.protocol_helper.set_buffer(info)
			self.state = self.states.SEND_INFO
		#
		if self.state is self.states.SEND_INFO:
			if self.protocol_helper.send(self.socket):
				self.protocol_helper = ProtocolHelper()
				if len(self.send_data) > 0:
					self.protocol_helper.set_buffer(self.send_data)
					self.state = self.states.SEND_DATA
				else:
					self.state = self.states.RECV_CONFIRMATION
				#
			#
		#
		if self.state is self.states.SEND_DATA:
			if self.protocol_helper.send(self.socket):
				self.protocol_helper = ProtocolHelper()
				self.state = self.states.RECV_CONFIRMATION
			#
		#
		if self.state is self.states.RECV_CONFIRMATION:
			response_size = 8
			if self.protocol_helper.recv(self.socket, response_size):
				response = self.protocol_helper.get_buffer()
				if response != b'RECEIVED':
					raise ProtocolException('Did not receive the expected message: {}'.format(response))
				#
				self.state = self.states.DONE
			#
		#
		if self.state is self.states.DONE:
			return True
		#
		return False
	#
#
class ReceiveDataProtocol(Protocol):
	def __init__(self, socket):
		self.socket = socket
		#
		self.states = enum.Enum('RECV_DATA_STATES', 'READY_TO_BEGIN RECV_INFO RECV_DATA SEND_CONFIRMATION DONE')
		self.state = self.states.READY_TO_BEGIN
		#
		self.protocol_helper = None
		self.data_size = None
		self.received_data = None
	#
	def _run_iteration(self):
		if self.state is self.states.READY_TO_BEGIN:
			self.protocol_helper = ProtocolHelper()
			self.state = self.states.RECV_INFO
		#
		if self.state is self.states.RECV_INFO:
			info_size = 20
			if self.protocol_helper.recv(self.socket, info_size):
				response = self.protocol_helper.get_buffer()
				self.data_size = int.from_bytes(response, byteorder='big', signed=False)
				self.protocol_helper = ProtocolHelper()
				if self.data_size > 0:
					self.state = self.states.RECV_DATA
				else:
					self.received_data = b''
					self.protocol_helper.set_buffer(b'RECEIVED')
					self.state = self.states.SEND_CONFIRMATION
				#
			#
		#
		if self.state is self.states.RECV_DATA:
			if self.protocol_helper.recv(self.socket, self.data_size):
				response = self.protocol_helper.get_buffer()
				self.received_data = response
				self.protocol_helper = ProtocolHelper()
				self.protocol_helper.set_buffer(b'RECEIVED')
				self.state = self.states.SEND_CONFIRMATION
			#
		#
		if self.state is self.states.SEND_CONFIRMATION:
			if self.protocol_helper.send(self.socket):
				self.state = self.states.DONE
			#
		#
		if self.state is self.states.DONE:
			return True
		#
		return False
	#
#
class ServerListener():
	def __init__(self, bind_endpoint, accept_callback):
		self.callback = accept_callback
		#
		self.s = socket.socket()
		self.s.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
		self.s.setblocking(0)
		self.s.bind(bind_endpoint)
		self.s.listen(1000)
	#
	def accept(self, block=True):
		if block:
			(readable, _, _) = select.select([self.s], [], [])
		else:
			readable = [self.s]
		#
		try:
			(newsock, endpoint) = self.s.accept()
			logging.debug("New client from %s:%d (fd=%d)",
						  endpoint[0], endpoint[1], newsock.fileno())
			self.callback(newsock)
			return True
		except BlockingIOError:
			return False
		#
	#
	def stop(self):
		self.s.shutdown(socket.SHUT_RDWR)
		# use 'shutdown' rather than 'close' since 'close' won't stop a blocking 'accept' call
	#
#
class SimpleClientConnectionProtocol(Protocol):
	def __init__(self, endpoint, total_bytes, data_generator=None, proxy=None, username=None):
		self.endpoint = endpoint
		self.data_generator = data_generator
		self.total_bytes = total_bytes
		self.proxy = proxy
		self.username = username
		#
		self.states = enum.Enum('CLIENT_CONN_STATES', 'READY_TO_BEGIN CONNECT_TO_PROXY PUSH_DATA DONE')
		self.state = self.states.READY_TO_BEGIN
		#
		self.socket = socket.socket()
		self.sub_protocol = None
		#
		if self.proxy is None:
			logging.debug('Socket %d connecting to endpoint %r...', self.socket.fileno(), self.endpoint)
			self.socket.connect(self.endpoint)
		else:
			logging.debug('Socket %d connecting to proxy %r...', self.socket.fileno(), self.proxy)
			self.socket.connect(self.proxy)
		#
	#
	def _run_iteration(self):
		if self.state is self.states.READY_TO_BEGIN:
			if self.proxy is None:
				self.sub_protocol = PushDataProtocol(self.socket, self.total_bytes, self.data_generator)
				self.state = self.states.PUSH_DATA
			else:
				self.sub_protocol = Socks4Protocol(self.socket, self.endpoint, username=self.username)
				self.state = self.states.CONNECT_TO_PROXY
			#
		#
		if self.state is self.states.CONNECT_TO_PROXY:
			if self.sub_protocol.run():
				self.sub_protocol = PushDataProtocol(self.socket, self.total_bytes, self.data_generator)
				self.state = self.states.PUSH_DATA
			#
		#
		if self.state is self.states.PUSH_DATA:
			if self.sub_protocol.run():
				self.state = self.states.DONE
			#
		#
		if self.state is self.states.DONE:
			return True
		#
		return False
	#
#
class SimpleServerConnectionProtocol(Protocol):
	def __init__(self, socket, conn_id, bandwidth_callback=None):
		self.socket = socket
		self.conn_id = conn_id
		self.bandwidth_callback = bandwidth_callback
		#
		self.states = enum.Enum('SERVER_CONN_STATES', 'READY_TO_BEGIN PULL_DATA DONE')
		self.state = self.states.READY_TO_BEGIN
		#
		self.sub_protocol = None
	#
	def _run_iteration(self):
		if self.state is self.states.READY_TO_BEGIN:
			self.sub_protocol = PullDataProtocol(self.socket)
			self.state = self.states.PULL_DATA
		#
		if self.state is self.states.PULL_DATA:
			if self.sub_protocol.run():
				if self.bandwidth_callback:
					self.bandwidth_callback(self.conn_id, self.sub_protocol.data_size, self.sub_protocol.calc_transfer_rate())
				#
				self.state = self.states.DONE
			#
		#
		if self.state is self.states.DONE:
			return True
		#
		return False
	#
#
if __name__ == '__main__':
	import sys
	logging.basicConfig(level=logging.DEBUG)
	#
	if sys.argv[1] == 'client':
		endpoint = ('127.0.0.1', 4747)
		#proxy = ('127.0.0.1', 9003)
		proxy = None
		username = bytes([x for x in os.urandom(12) if x != 0])
		#username = None
		data_MB = 4000
		#
		client = SimpleClientConnectionProtocol(endpoint, data_MB*2**20, proxy=proxy, username=username)
		client.run()
	elif sys.argv[1] == 'server':
		import multiprocessing
		import queue
		#
		endpoint = ('127.0.0.1', 4747)
		processes = []
		conn_counter = [0]
		#
		def bw_callback(conn_id, data_size, transfer_rate):
			logging.info('Avg Transferred (MB): %.4f', data_size/(1024**2))
			logging.info('Avg Transfer rate (MB/s): %.4f', transfer_rate/(1024**2))
		#
		def start_server_conn(socket, conn_id):
			server = SimpleServerConnectionProtocol(socket, conn_id, bandwidth_callback=bw_callback)
			try:
				server.run()
			except KeyboardInterrupt:
				socket.close()
			#
		#
		def accept_callback(socket):
			conn_id = conn_counter[0]
			conn_counter[0] += 1
			#
			p = multiprocessing.Process(target=start_server_conn, args=(socket, conn_id))
			processes.append(p)
			p.start()
		#
		l = ServerListener(endpoint, accept_callback)
		#
		try:
			while True:
				l.accept()
			#
		except KeyboardInterrupt:
			print()
		#
		for p in processes:
			p.join()
		#
	#
#