def read_raw_frame(rfile):
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()
header = Header(
fin=fin,
rsv=RsvBits(rsv1, rsv2, rsv3),
opcode=opcode,
payload_len=payload_len,
masking_key=masking_key,
)
masked_payload = consume(payload_len)
payload = masker.process(masked_payload)
frame = Frame(opcode=opcode,
payload=payload,
frame_finished=fin,
message_finished=fin)
return header, frame, consumed_bytes
def from_file(cls, fp):
"""
read a WebSocket frame header
"""
first_byte, second_byte = fp.safe_read(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_length > 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, = struct.unpack("!H", fp.safe_read(2))
else: # length_code == 127:
payload_length, = struct.unpack("!Q", fp.safe_read(8))
# masking key only present if mask bit set
if mask_bit == 1:
masking_key = fp.safe_read(4)
else:
masking_key = None
return cls(
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,
)