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import six
from . import packet
class Payload(object):
"""Engine.IO payload."""
def __init__(self, packets=None, encoded_payload=None):
self.packets = packets or []
if encoded_payload is not None:
self.decode(encoded_payload)
def encode(self, b64=False):
"""Encode the payload for transmission."""
encoded_payload = b''
for pkt in self.packets:
encoded_packet = pkt.encode(b64=b64)
packet_len = len(encoded_packet)
if b64:
encoded_payload += str(packet_len).encode('utf-8') + b':' + \
encoded_packet
else:
binary_len = b''
while packet_len != 0:
binary_len = six.int2byte(packet_len % 10) + binary_len
packet_len = int(packet_len / 10)
if not pkt.binary:
encoded_payload += b'\0'
else:
encoded_payload += b'\1'
encoded_payload += binary_len + b'\xff' + encoded_packet
return encoded_payload
def decode(self, encoded_payload):
"""Decode a transmitted payload."""
self.packets = []
while encoded_payload:
if six.byte2int(encoded_payload[0:1]) <= 1:
packet_len = 0
i = 1
while six.byte2int(encoded_payload[i:i + 1]) != 255:
packet_len = packet_len * 10 + six.byte2int(
encoded_payload[i:i + 1])
i += 1
self.packets.append(packet.Packet(
encoded_packet=encoded_payload[i + 1:i + 1 + packet_len]))
else:
i = encoded_payload.find(b':')
if i == -1:
raise ValueError('invalid payload')
# extracting the packet out of the payload is extremely
# inefficient, because the payload needs to be treated as
# binary, but the non-binary packets have to be parsed as
# unicode. Luckily this complication only applies to long
# polling, as the websocket transport sends packets
# individually wrapped.
packet_len = int(encoded_payload[0:i])
pkt = encoded_payload.decode('utf-8', errors='ignore')[
i + 1: i + 1 + packet_len].encode('utf-8')
self.packets.append(packet.Packet(encoded_packet=pkt))
# the engine.io protocol sends the packet length in
# utf-8 characters, but we need it in bytes to be able to
# jump to the next packet in the payload
packet_len = len(pkt)
encoded_payload = encoded_payload[i + 1 + packet_len:]
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