60 lines
1.6 KiB
Python
60 lines
1.6 KiB
Python
from librespot.crypto.Packet import Packet
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from librespot.crypto.Shannon import Shannon
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import struct
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class CipherPair:
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send_cipher: Shannon
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receive_cipher: Shannon
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send_nonce = 0
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receive_nonce = 0
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def __init__(self, send_key: bytes, receive_key: bytes):
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self.send_cipher = Shannon()
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self.send_cipher.key(send_key)
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self.send_nonce = 0
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self.receive_cipher = Shannon()
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self.receive_cipher.key(receive_key)
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self.receive_nonce = 0
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def send_encoded(self, conn, cmd: bytes, payload: bytes):
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self.send_cipher.nonce(self.send_nonce)
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self.send_nonce += 1
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buffer = b""
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buffer += cmd
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buffer += struct.pack(">H", len(payload))
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buffer += payload
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buffer = self.send_cipher.encrypt(buffer)
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mac = self.send_cipher.finish(4)
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conn.write(buffer)
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conn.write(mac)
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conn.flush()
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def receive_encoded(self, conn) -> Packet:
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try:
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self.receive_cipher.nonce(self.receive_nonce)
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self.receive_nonce += 1
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header_bytes = self.receive_cipher.decrypt(conn.read(3))
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cmd = struct.pack(">s", bytes([header_bytes[0]]))
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payload_length = (header_bytes[1] << 8) | (header_bytes[2] & 0xff)
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payload_bytes = self.receive_cipher.decrypt(
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conn.read(payload_length))
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mac = conn.read(4)
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expected_mac = self.receive_cipher.finish(4)
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if mac != expected_mac:
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raise RuntimeError()
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return Packet(cmd, payload_bytes)
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except IndexError:
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raise RuntimeError()
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