372 lines
12 KiB
Python
372 lines
12 KiB
Python
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# Author: Johan Hanssen Seferidis
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# License: MIT
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import sys
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import struct
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from base64 import b64encode
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from hashlib import sha1
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import logging
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from socket import error as SocketError
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import errno
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if sys.version_info[0] < 3:
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from SocketServer import ThreadingMixIn, TCPServer, StreamRequestHandler
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else:
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from socketserver import ThreadingMixIn, TCPServer, StreamRequestHandler
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logger = logging.getLogger(__name__)
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logging.basicConfig()
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'''
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+-+-+-+-+-------+-+-------------+-------------------------------+
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0 1 2 3
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0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
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+-+-+-+-+-------+-+-------------+-------------------------------+
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|F|R|R|R| opcode|M| Payload len | Extended payload length |
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|I|S|S|S| (4) |A| (7) | (16/64) |
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|N|V|V|V| |S| | (if payload len==126/127) |
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| |1|2|3| |K| | |
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+-+-+-+-+-------+-+-------------+ - - - - - - - - - - - - - - - +
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| Extended payload length continued, if payload len == 127 |
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+ - - - - - - - - - - - - - - - +-------------------------------+
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| Payload Data continued ... |
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+---------------------------------------------------------------+
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'''
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FIN = 0x80
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OPCODE = 0x0f
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MASKED = 0x80
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PAYLOAD_LEN = 0x7f
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PAYLOAD_LEN_EXT16 = 0x7e
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PAYLOAD_LEN_EXT64 = 0x7f
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OPCODE_CONTINUATION = 0x0
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OPCODE_TEXT = 0x1
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OPCODE_BINARY = 0x2
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OPCODE_CLOSE_CONN = 0x8
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OPCODE_PING = 0x9
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OPCODE_PONG = 0xA
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# -------------------------------- API ---------------------------------
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class API():
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def run_forever(self):
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try:
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logger.info("Listening on port %d for clients.." % self.port)
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self.serve_forever()
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except KeyboardInterrupt:
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self.server_close()
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logger.info("Server terminated.")
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except Exception as e:
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logger.error(str(e), exc_info=True)
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exit(1)
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def new_client(self, client, server):
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pass
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def client_left(self, client, server):
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pass
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def message_received(self, client, server, message):
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pass
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def set_fn_new_client(self, fn):
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self.new_client = fn
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def set_fn_client_left(self, fn):
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self.client_left = fn
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def set_fn_message_received(self, fn):
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self.message_received = fn
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def send_message(self, client, msg):
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self._unicast_(client, msg)
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def send_message_to_all(self, msg):
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self._multicast_(msg)
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# ------------------------- Implementation -----------------------------
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class WebsocketServer(ThreadingMixIn, TCPServer, API):
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"""
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A websocket server waiting for clients to connect.
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Args:
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port(int): Port to bind to
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host(str): Hostname or IP to listen for connections. By default 127.0.0.1
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is being used. To accept connections from any client, you should use
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0.0.0.0.
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loglevel: Logging level from logging module to use for logging. By default
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warnings and errors are being logged.
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Properties:
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clients(list): A list of connected clients. A client is a dictionary
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like below.
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{
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'id' : id,
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'handler' : handler,
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'address' : (addr, port)
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}
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"""
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allow_reuse_address = True
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daemon_threads = True # comment to keep threads alive until finished
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clients = []
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id_counter = 0
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def __init__(self, port, host='127.0.0.1', loglevel=logging.WARNING):
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logger.setLevel(loglevel)
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TCPServer.__init__(self, (host, port), WebSocketHandler)
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self.port = self.socket.getsockname()[1]
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def _message_received_(self, handler, msg):
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self.message_received(self.handler_to_client(handler), self, msg)
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def _ping_received_(self, handler, msg):
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handler.send_pong(msg)
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def _pong_received_(self, handler, msg):
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pass
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def _new_client_(self, handler):
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self.id_counter += 1
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client = {
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'id': self.id_counter,
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'handler': handler,
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'address': handler.client_address
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}
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self.clients.append(client)
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self.new_client(client, self)
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def _client_left_(self, handler):
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client = self.handler_to_client(handler)
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self.client_left(client, self)
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if client in self.clients:
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self.clients.remove(client)
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def _unicast_(self, to_client, msg):
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to_client['handler'].send_message(msg)
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def _multicast_(self, msg):
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for client in self.clients:
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self._unicast_(client, msg)
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def handler_to_client(self, handler):
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for client in self.clients:
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if client['handler'] == handler:
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return client
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class WebSocketHandler(StreamRequestHandler):
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def __init__(self, socket, addr, server):
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self.server = server
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StreamRequestHandler.__init__(self, socket, addr, server)
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def setup(self):
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StreamRequestHandler.setup(self)
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self.keep_alive = True
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self.handshake_done = False
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self.valid_client = False
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def handle(self):
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while self.keep_alive:
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if not self.handshake_done:
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self.handshake()
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elif self.valid_client:
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self.read_next_message()
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def read_bytes(self, num):
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# python3 gives ordinal of byte directly
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bytes = self.rfile.read(num)
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if sys.version_info[0] < 3:
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return map(ord, bytes)
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else:
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return bytes
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def read_next_message(self):
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try:
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b1, b2 = self.read_bytes(2)
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except SocketError as e: # to be replaced with ConnectionResetError for py3
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if e.errno == errno.ECONNRESET:
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logger.info("Client closed connection.")
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print("Error: {}".format(e))
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self.keep_alive = 0
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return
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b1, b2 = 0, 0
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except ValueError as e:
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b1, b2 = 0, 0
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fin = b1 & FIN
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opcode = b1 & OPCODE
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masked = b2 & MASKED
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payload_length = b2 & PAYLOAD_LEN
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if opcode == OPCODE_CLOSE_CONN:
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logger.info("Client asked to close connection.")
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self.keep_alive = 0
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return
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if not masked:
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logger.warn("Client must always be masked.")
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self.keep_alive = 0
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return
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if opcode == OPCODE_CONTINUATION:
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logger.warn("Continuation frames are not supported.")
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return
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elif opcode == OPCODE_BINARY:
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logger.warn("Binary frames are not supported.")
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return
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elif opcode == OPCODE_TEXT:
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opcode_handler = self.server._message_received_
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elif opcode == OPCODE_PING:
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opcode_handler = self.server._ping_received_
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elif opcode == OPCODE_PONG:
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opcode_handler = self.server._pong_received_
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else:
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logger.warn("Unknown opcode %#x." % opcode)
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self.keep_alive = 0
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return
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if payload_length == 126:
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payload_length = struct.unpack(">H", self.rfile.read(2))[0]
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elif payload_length == 127:
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payload_length = struct.unpack(">Q", self.rfile.read(8))[0]
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masks = self.read_bytes(4)
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message_bytes = bytearray()
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for message_byte in self.read_bytes(payload_length):
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message_byte ^= masks[len(message_bytes) % 4]
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message_bytes.append(message_byte)
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opcode_handler(self, message_bytes.decode('utf8'))
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def send_message(self, message):
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self.send_text(message)
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def send_pong(self, message):
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self.send_text(message, OPCODE_PONG)
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def send_text(self, message, opcode=OPCODE_TEXT):
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"""
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Important: Fragmented(=continuation) messages are not supported since
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their usage cases are limited - when we don't know the payload length.
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"""
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# Validate message
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if isinstance(message, bytes):
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message = try_decode_UTF8(message) # this is slower but ensures we have UTF-8
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if not message:
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logger.warning("Can\'t send message, message is not valid UTF-8")
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return False
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elif sys.version_info < (3,0) and (isinstance(message, str) or isinstance(message, unicode)):
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pass
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elif isinstance(message, str):
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pass
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else:
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logger.warning('Can\'t send message, message has to be a string or bytes. Given type is %s' % type(message))
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return False
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header = bytearray()
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payload = encode_to_UTF8(message)
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payload_length = len(payload)
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# Normal payload
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if payload_length <= 125:
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header.append(FIN | opcode)
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header.append(payload_length)
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# Extended payload
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elif payload_length >= 126 and payload_length <= 65535:
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header.append(FIN | opcode)
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header.append(PAYLOAD_LEN_EXT16)
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header.extend(struct.pack(">H", payload_length))
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# Huge extended payload
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elif payload_length < 18446744073709551616:
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header.append(FIN | opcode)
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header.append(PAYLOAD_LEN_EXT64)
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header.extend(struct.pack(">Q", payload_length))
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else:
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raise Exception("Message is too big. Consider breaking it into chunks.")
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return
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self.request.send(header + payload)
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def read_http_headers(self):
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headers = {}
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# first line should be HTTP GET
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http_get = self.rfile.readline().decode().strip()
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assert http_get.upper().startswith('GET')
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# remaining should be headers
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while True:
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header = self.rfile.readline().decode().strip()
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if not header:
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break
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head, value = header.split(':', 1)
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headers[head.lower().strip()] = value.strip()
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return headers
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def handshake(self):
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headers = self.read_http_headers()
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try:
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assert headers['upgrade'].lower() == 'websocket'
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except AssertionError:
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self.keep_alive = False
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return
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try:
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key = headers['sec-websocket-key']
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except KeyError:
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logger.warning("Client tried to connect but was missing a key")
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self.keep_alive = False
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return
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response = self.make_handshake_response(key)
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self.handshake_done = self.request.send(response.encode())
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self.valid_client = True
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self.server._new_client_(self)
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@classmethod
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def make_handshake_response(cls, key):
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return \
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'HTTP/1.1 101 Switching Protocols\r\n'\
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'Upgrade: websocket\r\n' \
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'Connection: Upgrade\r\n' \
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'Sec-WebSocket-Accept: %s\r\n' \
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'\r\n' % cls.calculate_response_key(key)
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@classmethod
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def calculate_response_key(cls, key):
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GUID = '258EAFA5-E914-47DA-95CA-C5AB0DC85B11'
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hash = sha1(key.encode() + GUID.encode())
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response_key = b64encode(hash.digest()).strip()
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return response_key.decode('ASCII')
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def finish(self):
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self.server._client_left_(self)
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def encode_to_UTF8(data):
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try:
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return data.encode('UTF-8')
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except UnicodeEncodeError as e:
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logger.error("Could not encode data to UTF-8 -- %s" % e)
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return False
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except Exception as e:
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raise(e)
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return False
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def try_decode_UTF8(data):
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try:
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return data.decode('utf-8')
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except UnicodeDecodeError:
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return False
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except Exception as e:
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raise(e)
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