mirror of
https://github.com/Grasscutters/mitmproxy.git
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115 lines
3.2 KiB
Python
115 lines
3.2 KiB
Python
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# Colleciton of utility functions that implement small portions of the RFC6455
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# WebSockets Protocol Useful for building WebSocket clients and servers.
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#
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# Emphassis is on readabilty, simplicity and modularity, not performance or
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# completeness
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#
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# This is a work in progress and does not yet contain all the utilites need to
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# create fully complient client/servers #
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# Spec: https://tools.ietf.org/html/rfc6455
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# The magic sha that websocket servers must know to prove they understand
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# RFC6455
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from __future__ import absolute_import
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import base64
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import hashlib
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import os
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from ..http import Headers
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from .. import utils
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websockets_magic = '258EAFA5-E914-47DA-95CA-C5AB0DC85B11'
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VERSION = "13"
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HEADER_WEBSOCKET_KEY = 'sec-websocket-key'
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HEADER_WEBSOCKET_ACCEPT = 'sec-websocket-accept'
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HEADER_WEBSOCKET_VERSION = 'sec-websocket-version'
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class Masker(object):
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"""
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Data sent from the server must be masked to prevent malicious clients
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from sending data over the wire in predictable patterns
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Servers do not have to mask data they send to the client.
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https://tools.ietf.org/html/rfc6455#section-5.3
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"""
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def __init__(self, key):
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self.key = key
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self.masks = [utils.bytes_to_int(byte) for byte in key]
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self.offset = 0
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def mask(self, offset, data):
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result = ""
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for c in data:
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result += chr(ord(c) ^ self.masks[offset % 4])
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offset += 1
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return result
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def __call__(self, data):
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ret = self.mask(self.offset, data)
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self.offset += len(ret)
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return ret
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class WebsocketsProtocol(object):
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def __init__(self):
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pass
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@classmethod
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def client_handshake_headers(self, key=None, version=VERSION):
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"""
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Create the headers for a valid HTTP upgrade request. If Key is not
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specified, it is generated, and can be found in sec-websocket-key in
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the returned header set.
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Returns an instance of Headers
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"""
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if not key:
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key = base64.b64encode(os.urandom(16)).decode('utf-8')
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return Headers([
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('Connection', 'Upgrade'),
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('Upgrade', 'websocket'),
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(HEADER_WEBSOCKET_KEY, key),
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(HEADER_WEBSOCKET_VERSION, version)
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])
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@classmethod
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def server_handshake_headers(self, key):
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"""
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The server response is a valid HTTP 101 response.
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"""
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return Headers(
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[
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('Connection', 'Upgrade'),
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('Upgrade', 'websocket'),
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(HEADER_WEBSOCKET_ACCEPT, self.create_server_nonce(key))
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]
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)
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@classmethod
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def check_client_handshake(self, headers):
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if headers.get("upgrade") != "websocket":
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return
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return headers.get(HEADER_WEBSOCKET_KEY)
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@classmethod
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def check_server_handshake(self, headers):
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if headers.get("upgrade") != "websocket":
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return
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return headers.get(HEADER_WEBSOCKET_ACCEPT)
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@classmethod
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def create_server_nonce(self, client_nonce):
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return base64.b64encode(
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hashlib.sha1(client_nonce + websockets_magic).hexdigest().decode('hex')
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)
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