mirror of
https://github.com/Grasscutters/mitmproxy.git
synced 2024-11-23 08:11:00 +00:00
369 lines
12 KiB
Python
369 lines
12 KiB
Python
from __future__ import absolute_import
|
|
import base64
|
|
import hashlib
|
|
import os
|
|
import struct
|
|
import io
|
|
|
|
from . import utils, odict
|
|
|
|
# Colleciton of utility functions that implement small portions of the RFC6455
|
|
# WebSockets Protocol Useful for building WebSocket clients and servers.
|
|
#
|
|
# Emphassis is on readabilty, simplicity and modularity, not performance or
|
|
# completeness
|
|
#
|
|
# This is a work in progress and does not yet contain all the utilites need to
|
|
# create fully complient client/servers #
|
|
# Spec: https://tools.ietf.org/html/rfc6455
|
|
|
|
# The magic sha that websocket servers must know to prove they understand
|
|
# RFC6455
|
|
websockets_magic = '258EAFA5-E914-47DA-95CA-C5AB0DC85B11'
|
|
VERSION = "13"
|
|
MAX_16_BIT_INT = (1 << 16)
|
|
MAX_64_BIT_INT = (1 << 64)
|
|
|
|
|
|
OPCODE = utils.BiDi(
|
|
CONTINUE = 0x00,
|
|
TEXT = 0x01,
|
|
BINARY = 0x02,
|
|
CLOSE = 0x08,
|
|
PING = 0x09,
|
|
PONG = 0x0a
|
|
)
|
|
|
|
|
|
def apply_mask(message, masking_key):
|
|
"""
|
|
Data sent from the server must be masked to prevent malicious clients
|
|
from sending data over the wire in predictable patterns
|
|
|
|
This method both encodes and decodes strings with the provided mask
|
|
|
|
Servers do not have to mask data they send to the client.
|
|
https://tools.ietf.org/html/rfc6455#section-5.3
|
|
"""
|
|
masks = [utils.bytes_to_int(byte) for byte in masking_key]
|
|
result = ""
|
|
for char in message:
|
|
result += chr(ord(char) ^ masks[len(result) % 4])
|
|
return result
|
|
|
|
|
|
def client_handshake_headers(key=None, version=VERSION):
|
|
"""
|
|
Create the headers for a valid HTTP upgrade request. If Key is not
|
|
specified, it is generated, and can be found in sec-websocket-key in
|
|
the returned header set.
|
|
|
|
Returns an instance of ODictCaseless
|
|
"""
|
|
if not key:
|
|
key = base64.b64encode(os.urandom(16)).decode('utf-8')
|
|
return odict.ODictCaseless([
|
|
('Connection', 'Upgrade'),
|
|
('Upgrade', 'websocket'),
|
|
('Sec-WebSocket-Key', key),
|
|
('Sec-WebSocket-Version', version)
|
|
])
|
|
|
|
|
|
def server_handshake_headers(key):
|
|
"""
|
|
The server response is a valid HTTP 101 response.
|
|
"""
|
|
return odict.ODictCaseless(
|
|
[
|
|
('Connection', 'Upgrade'),
|
|
('Upgrade', 'websocket'),
|
|
('Sec-WebSocket-Accept', create_server_nonce(key))
|
|
]
|
|
)
|
|
|
|
|
|
def make_length_code(len):
|
|
"""
|
|
A websockets frame contains an initial length_code, and an optional
|
|
extended length code to represent the actual length if length code is
|
|
larger than 125
|
|
"""
|
|
if len <= 125:
|
|
return len
|
|
elif len >= 126 and len <= 65535:
|
|
return 126
|
|
else:
|
|
return 127
|
|
|
|
|
|
def check_client_handshake(headers):
|
|
if headers.get_first("upgrade", None) != "websocket":
|
|
return
|
|
return headers.get_first('sec-websocket-key')
|
|
|
|
|
|
def check_server_handshake(headers):
|
|
if headers.get_first("upgrade", None) != "websocket":
|
|
return
|
|
return headers.get_first('sec-websocket-accept')
|
|
|
|
|
|
def create_server_nonce(client_nonce):
|
|
return base64.b64encode(
|
|
hashlib.sha1(client_nonce + websockets_magic).hexdigest().decode('hex')
|
|
)
|
|
|
|
|
|
DEFAULT = object()
|
|
|
|
|
|
class FrameHeader:
|
|
def __init__(
|
|
self,
|
|
opcode = OPCODE.TEXT,
|
|
payload_length = 0,
|
|
fin = False,
|
|
rsv1 = False,
|
|
rsv2 = False,
|
|
rsv3 = False,
|
|
masking_key = DEFAULT,
|
|
mask = DEFAULT,
|
|
length_code = DEFAULT
|
|
):
|
|
if not 0 <= opcode < 2 ** 4:
|
|
raise ValueError("opcode must be 0-16")
|
|
self.opcode = opcode
|
|
self.payload_length = payload_length
|
|
self.fin = fin
|
|
self.rsv1 = rsv1
|
|
self.rsv2 = rsv2
|
|
self.rsv3 = rsv3
|
|
|
|
if length_code is DEFAULT:
|
|
self.length_code = make_length_code(self.payload_length)
|
|
else:
|
|
self.length_code = length_code
|
|
|
|
if mask is DEFAULT and masking_key is DEFAULT:
|
|
self.mask = False
|
|
self.masking_key = ""
|
|
elif mask is DEFAULT:
|
|
self.mask = 1
|
|
self.masking_key = masking_key
|
|
elif masking_key is DEFAULT:
|
|
self.mask = mask
|
|
self.masking_key = os.urandom(4)
|
|
else:
|
|
self.mask = mask
|
|
self.masking_key = masking_key
|
|
|
|
if self.masking_key and len(self.masking_key) != 4:
|
|
raise ValueError("Masking key must be 4 bytes.")
|
|
|
|
def human_readable(self):
|
|
return "\n".join([
|
|
("fin - " + str(self.fin)),
|
|
("rsv1 - " + str(self.rsv1)),
|
|
("rsv2 - " + str(self.rsv2)),
|
|
("rsv3 - " + str(self.rsv3)),
|
|
("opcode - " + str(self.opcode)),
|
|
("mask - " + str(self.mask)),
|
|
("length_code - " + str(self.length_code)),
|
|
("masking_key - " + repr(str(self.masking_key))),
|
|
])
|
|
|
|
def to_bytes(self):
|
|
first_byte = utils.setbit(0, 7, self.fin)
|
|
first_byte = utils.setbit(first_byte, 6, self.rsv1)
|
|
first_byte = utils.setbit(first_byte, 5, self.rsv2)
|
|
first_byte = utils.setbit(first_byte, 4, self.rsv3)
|
|
first_byte = first_byte | self.opcode
|
|
|
|
second_byte = utils.setbit(self.length_code, 7, self.mask)
|
|
|
|
b = chr(first_byte) + chr(second_byte)
|
|
|
|
if self.payload_length < 126:
|
|
pass
|
|
elif self.payload_length < MAX_16_BIT_INT:
|
|
# '!H' pack as 16 bit unsigned short
|
|
# add 2 byte extended payload length
|
|
b += struct.pack('!H', self.payload_length)
|
|
elif self.payload_length < MAX_64_BIT_INT:
|
|
# '!Q' = pack as 64 bit unsigned long long
|
|
# add 8 bytes extended payload length
|
|
b += struct.pack('!Q', self.payload_length)
|
|
if self.masking_key is not None:
|
|
b += self.masking_key
|
|
return b
|
|
|
|
@classmethod
|
|
def from_file(klass, fp):
|
|
"""
|
|
read a websockets frame header
|
|
"""
|
|
first_byte = utils.bytes_to_int(fp.read(1))
|
|
second_byte = utils.bytes_to_int(fp.read(1))
|
|
|
|
fin = utils.getbit(first_byte, 7)
|
|
rsv1 = utils.getbit(first_byte, 6)
|
|
rsv2 = utils.getbit(first_byte, 5)
|
|
rsv3 = utils.getbit(first_byte, 4)
|
|
# grab right-most 4 bits
|
|
opcode = first_byte & 15
|
|
mask_bit = utils.getbit(second_byte, 7)
|
|
# grab the next 7 bits
|
|
length_code = second_byte & 127
|
|
|
|
# payload_lengthy > 125 indicates you need to read more bytes
|
|
# to get the actual payload length
|
|
if length_code <= 125:
|
|
payload_length = length_code
|
|
elif length_code == 126:
|
|
payload_length = utils.bytes_to_int(fp.read(2))
|
|
elif length_code == 127:
|
|
payload_length = utils.bytes_to_int(fp.read(8))
|
|
|
|
# masking key only present if mask bit set
|
|
if mask_bit == 1:
|
|
masking_key = fp.read(4)
|
|
else:
|
|
masking_key = None
|
|
|
|
return klass(
|
|
fin = fin,
|
|
rsv1 = rsv1,
|
|
rsv2 = rsv2,
|
|
rsv3 = rsv3,
|
|
opcode = opcode,
|
|
mask = mask_bit,
|
|
length_code = length_code,
|
|
payload_length = payload_length,
|
|
masking_key = masking_key,
|
|
)
|
|
|
|
def __eq__(self, other):
|
|
return self.to_bytes() == other.to_bytes()
|
|
|
|
|
|
class Frame(object):
|
|
"""
|
|
Represents one websockets frame.
|
|
Constructor takes human readable forms of the frame components
|
|
from_bytes() is also avaliable.
|
|
|
|
WebSockets Frame as defined in RFC6455
|
|
|
|
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
|
|
+-+-+-+-+-------+-+-------------+-------------------------------+
|
|
|F|R|R|R| opcode|M| Payload len | Extended payload length |
|
|
|I|S|S|S| (4) |A| (7) | (16/64) |
|
|
|N|V|V|V| |S| | (if payload len==126/127) |
|
|
| |1|2|3| |K| | |
|
|
+-+-+-+-+-------+-+-------------+ - - - - - - - - - - - - - - - +
|
|
| Extended payload length continued, if payload len == 127 |
|
|
+ - - - - - - - - - - - - - - - +-------------------------------+
|
|
| |Masking-key, if MASK set to 1 |
|
|
+-------------------------------+-------------------------------+
|
|
| Masking-key (continued) | Payload Data |
|
|
+-------------------------------- - - - - - - - - - - - - - - - +
|
|
: Payload Data continued ... :
|
|
+ - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - +
|
|
| Payload Data continued ... |
|
|
+---------------------------------------------------------------+
|
|
"""
|
|
def __init__(self, payload = "", **kwargs):
|
|
self.payload = payload
|
|
kwargs["payload_length"] = kwargs.get("payload_length", len(payload))
|
|
self.header = FrameHeader(**kwargs)
|
|
|
|
@classmethod
|
|
def default(cls, message, from_client = False):
|
|
"""
|
|
Construct a basic websocket frame from some default values.
|
|
Creates a non-fragmented text frame.
|
|
"""
|
|
if from_client:
|
|
mask_bit = 1
|
|
masking_key = os.urandom(4)
|
|
else:
|
|
mask_bit = 0
|
|
masking_key = None
|
|
|
|
return cls(
|
|
message,
|
|
fin = 1, # final frame
|
|
opcode = OPCODE.TEXT, # text
|
|
mask = mask_bit,
|
|
masking_key = masking_key,
|
|
)
|
|
|
|
@classmethod
|
|
def from_bytes(cls, bytestring):
|
|
"""
|
|
Construct a websocket frame from an in-memory bytestring
|
|
to construct a frame from a stream of bytes, use from_file() directly
|
|
"""
|
|
return cls.from_file(io.BytesIO(bytestring))
|
|
|
|
def human_readable(self):
|
|
return "\n".join([
|
|
("fin - " + str(self.header.fin)),
|
|
("rsv1 - " + str(self.header.rsv1)),
|
|
("rsv2 - " + str(self.header.rsv2)),
|
|
("rsv3 - " + str(self.header.rsv3)),
|
|
("opcode - " + str(self.header.opcode)),
|
|
("mask - " + str(self.header.mask)),
|
|
("length_code - " + str(self.header.length_code)),
|
|
("masking_key - " + repr(str(self.header.masking_key))),
|
|
("payload - " + repr(str(self.payload))),
|
|
])
|
|
|
|
def to_bytes(self):
|
|
"""
|
|
Serialize the frame back into the wire format, returns a bytestring
|
|
If you haven't checked is_valid_frame() then there's no guarentees
|
|
that the serialized bytes will be correct. see safe_to_bytes()
|
|
"""
|
|
b = self.header.to_bytes()
|
|
if self.header.masking_key:
|
|
b += apply_mask(self.payload, self.header.masking_key)
|
|
else:
|
|
b += self.payload
|
|
return b
|
|
|
|
def to_file(self, writer):
|
|
writer.write(self.to_bytes())
|
|
writer.flush()
|
|
|
|
@classmethod
|
|
def from_file(cls, fp):
|
|
"""
|
|
read a websockets frame sent by a server or client
|
|
|
|
fp is a "file like" object that could be backed by a network
|
|
stream or a disk or an in memory stream reader
|
|
"""
|
|
header = FrameHeader.from_file(fp)
|
|
payload = fp.read(header.payload_length)
|
|
|
|
if header.mask == 1 and header.masking_key:
|
|
payload = apply_mask(payload, header.masking_key)
|
|
|
|
return cls(
|
|
payload,
|
|
fin = header.fin,
|
|
opcode = header.opcode,
|
|
mask = header.mask,
|
|
payload_length = header.payload_length,
|
|
masking_key = header.masking_key,
|
|
rsv1 = header.rsv1,
|
|
rsv2 = header.rsv2,
|
|
rsv3 = header.rsv3,
|
|
length_code = header.length_code
|
|
)
|
|
|
|
def __eq__(self, other):
|
|
return self.to_bytes() == other.to_bytes()
|