File size: 1,935 Bytes
d3de7c1 | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 | import ipaddress
from typing import Tuple
from cryptography.hazmat.primitives import hashes
from cryptography.hazmat.primitives.asymmetric import padding, rsa
from ..buffer import Buffer
from ..tls import pull_opaque, push_opaque
from .connection import NetworkAddress
def encode_address(addr: NetworkAddress) -> bytes:
return ipaddress.ip_address(addr[0]).packed + bytes([addr[1] >> 8, addr[1] & 0xFF])
class QuicRetryTokenHandler:
def __init__(self) -> None:
self._key = rsa.generate_private_key(public_exponent=65537, key_size=2048)
def create_token(
self,
addr: NetworkAddress,
original_destination_connection_id: bytes,
retry_source_connection_id: bytes,
) -> bytes:
buf = Buffer(capacity=512)
push_opaque(buf, 1, encode_address(addr))
push_opaque(buf, 1, original_destination_connection_id)
push_opaque(buf, 1, retry_source_connection_id)
return self._key.public_key().encrypt(
buf.data,
padding.OAEP(
mgf=padding.MGF1(hashes.SHA256()), algorithm=hashes.SHA256(), label=None
),
)
def validate_token(self, addr: NetworkAddress, token: bytes) -> Tuple[bytes, bytes]:
buf = Buffer(
data=self._key.decrypt(
token,
padding.OAEP(
mgf=padding.MGF1(hashes.SHA256()),
algorithm=hashes.SHA256(),
label=None,
),
)
)
encoded_addr = pull_opaque(buf, 1)
original_destination_connection_id = pull_opaque(buf, 1)
retry_source_connection_id = pull_opaque(buf, 1)
if encoded_addr != encode_address(addr):
raise ValueError("Remote address does not match.")
return original_destination_connection_id, retry_source_connection_id
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