openwebrx-clone/owrx/websocket.py
2019-07-21 19:40:28 +02:00

126 lines
4.7 KiB
Python

import base64
import hashlib
import json
import logging
logger = logging.getLogger(__name__)
class WebSocketConnection(object):
def __init__(self, handler, messageHandler):
self.handler = handler
self.messageHandler = messageHandler
my_headers = self.handler.headers.items()
my_header_keys = list(map(lambda x: x[0], my_headers))
h_key_exists = lambda x: my_header_keys.count(x)
h_value = lambda x: my_headers[my_header_keys.index(x)][1]
if (
(not h_key_exists("Upgrade"))
or not (h_value("Upgrade") == "websocket")
or (not h_key_exists("Sec-WebSocket-Key"))
):
raise WebSocketException
ws_key = h_value("Sec-WebSocket-Key")
shakey = hashlib.sha1()
shakey.update("{ws_key}258EAFA5-E914-47DA-95CA-C5AB0DC85B11".format(ws_key=ws_key).encode())
ws_key_toreturn = base64.b64encode(shakey.digest())
self.handler.wfile.write(
"HTTP/1.1 101 Switching Protocols\r\nUpgrade: websocket\r\nConnection: Upgrade\r\nSec-WebSocket-Accept: {0}\r\nCQ-CQ-de: HA5KFU\r\n\r\n".format(
ws_key_toreturn.decode()
).encode()
)
def get_header(self, size, opcode):
ws_first_byte = 0b10000000 | (opcode & 0x0F)
if size > 2 ** 16 - 1:
# frame size can be increased up to 2^64 by setting the size to 127
# anything beyond that would need to be segmented into frames. i don't really think we'll need more.
return bytes(
[
ws_first_byte,
127,
(size >> 56) & 0xFF,
(size >> 48) & 0xFF,
(size >> 40) & 0xFF,
(size >> 32) & 0xFF,
(size >> 24) & 0xFF,
(size >> 16) & 0xFF,
(size >> 8) & 0xFF,
size & 0xFF,
]
)
elif size > 125:
# up to 2^16 can be sent using the extended payload size field by putting the size to 126
return bytes([ws_first_byte, 126, (size >> 8) & 0xFF, size & 0xFF])
else:
# 125 bytes binary message in a single unmasked frame
return bytes([ws_first_byte, size])
def send(self, data):
# convenience
if type(data) == dict:
# allow_nan = False disallows NaN and Infinty to be encoded. Browser JSON will not parse them anyway.
data = json.dumps(data, allow_nan=False)
# string-type messages are sent as text frames
if type(data) == str:
header = self.get_header(len(data), 1)
data_to_send = header + data.encode("utf-8")
# anything else as binary
else:
header = self.get_header(len(data), 2)
data_to_send = header + data
written = self.handler.wfile.write(data_to_send)
if written != len(data_to_send):
logger.error("incomplete write! closing socket!")
self.close()
else:
self.handler.wfile.flush()
def read_loop(self):
open = True
while open:
header = self.handler.rfile.read(2)
opcode = header[0] & 0x0F
length = header[1] & 0x7F
mask = (header[1] & 0x80) >> 7
if length == 126:
header = self.handler.rfile.read(2)
length = (header[0] << 8) + header[1]
if mask:
masking_key = self.handler.rfile.read(4)
data = self.handler.rfile.read(length)
if mask:
data = bytes([b ^ masking_key[index % 4] for (index, b) in enumerate(data)])
if opcode == 1:
message = data.decode("utf-8")
self.messageHandler.handleTextMessage(self, message)
elif opcode == 2:
self.messageHandler.handleBinaryMessage(self, data)
elif opcode == 8:
open = False
self.messageHandler.handleClose(self)
else:
logger.warning("unsupported opcode: {0}".format(opcode))
def close(self):
try:
header = self.get_header(0, 8)
self.handler.wfile.write(header)
self.handler.wfile.flush()
except ValueError:
logger.exception("ValueError while writing close frame:")
except OSError:
logger.exception("OSError while writing close frame:")
try:
self.handler.finish()
self.handler.connection.close()
except Exception:
logger.exception("while closing connection:")
class WebSocketException(Exception):
pass