Current File : //lib/python3/dist-packages/mitmproxy/net/websocket.py
"""
Collection of WebSocket protocol utility functions (RFC6455)
Spec: https://tools.ietf.org/html/rfc6455
"""
import base64
import hashlib
import os
import struct
from wsproto.utilities import ACCEPT_GUID
from wsproto.handshake import WEBSOCKET_VERSION
from wsproto.frame_protocol import RsvBits, Header, Frame, XorMaskerSimple, XorMaskerNull
from mitmproxy.net import http
from mitmproxy.utils import bits, strutils
def read_frame(rfile, parse=True):
"""
Reads a full WebSocket frame from a file-like object.
Returns a parsed frame header, parsed frame, and the consumed bytes.
"""
consumed_bytes = b''
def consume(len):
nonlocal consumed_bytes
d = rfile.safe_read(len)
consumed_bytes += d
return d
first_byte, second_byte = consume(2)
fin = bits.getbit(first_byte, 7)
rsv1 = bits.getbit(first_byte, 6)
rsv2 = bits.getbit(first_byte, 5)
rsv3 = bits.getbit(first_byte, 4)
opcode = first_byte & 0xF
mask_bit = bits.getbit(second_byte, 7)
length_code = second_byte & 0x7F
# payload_len > 125 indicates you need to read more bytes
# to get the actual payload length
if length_code <= 125:
payload_len = length_code
elif length_code == 126:
payload_len, = struct.unpack("!H", consume(2))
else: # length_code == 127:
payload_len, = struct.unpack("!Q", consume(8))
# masking key only present if mask bit set
if mask_bit == 1:
masking_key = consume(4)
masker = XorMaskerSimple(masking_key)
else:
masking_key = None
masker = XorMaskerNull()
masked_payload = consume(payload_len)
if parse:
header = Header(
fin=fin,
rsv=RsvBits(rsv1, rsv2, rsv3),
opcode=opcode,
payload_len=payload_len,
masking_key=masking_key,
)
frame = Frame(
opcode=opcode,
payload=masker.process(masked_payload),
frame_finished=fin,
message_finished=fin
)
else:
header = None
frame = None
return header, frame, consumed_bytes
def client_handshake_headers(version=None, key=None, protocol=None, extensions=None):
"""
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 http.Headers
"""
if version is None:
version = WEBSOCKET_VERSION
if key is None:
key = base64.b64encode(os.urandom(16)).decode('ascii')
h = http.Headers(
connection="upgrade",
upgrade="websocket",
sec_websocket_version=version,
sec_websocket_key=key,
)
if protocol is not None:
h['sec-websocket-protocol'] = protocol
if extensions is not None:
h['sec-websocket-extensions'] = extensions
return h
def server_handshake_headers(client_key, protocol=None, extensions=None):
"""
The server response is a valid HTTP 101 response.
Returns an instance of http.Headers
"""
h = http.Headers(
connection="upgrade",
upgrade="websocket",
sec_websocket_accept=create_server_nonce(client_key),
)
if protocol is not None:
h['sec-websocket-protocol'] = protocol
if extensions is not None:
h['sec-websocket-extensions'] = extensions
return h
def check_handshake(headers):
return (
"upgrade" in headers.get("connection", "").lower() and
headers.get("upgrade", "").lower() == "websocket" and
(headers.get("sec-websocket-key") is not None or headers.get("sec-websocket-accept") is not None)
)
def create_server_nonce(client_nonce):
return base64.b64encode(hashlib.sha1(strutils.always_bytes(client_nonce) + ACCEPT_GUID).digest())
def check_client_version(headers):
return headers.get("sec-websocket-version", "") == WEBSOCKET_VERSION
def get_extensions(headers):
return headers.get("sec-websocket-extensions", None)
def get_protocol(headers):
return headers.get("sec-websocket-protocol", None)
def get_client_key(headers):
return headers.get("sec-websocket-key", None)
def get_server_accept(headers):
return headers.get("sec-websocket-accept", None)
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