2024-09-16 23:07:38 +03:00

208 lines
7.7 KiB
Python

import asyncio
import socket
import ipaddress
import struct
import secrets
import dataclasses
import enum
from ... import tools
from ... import aiotools
from ...logging import get_logger
# =====
class StunNatType(enum.Enum):
ERROR = ""
BLOCKED = "Blocked"
OPEN_INTERNET = "Open Internet"
SYMMETRIC_UDP_FW = "Symmetric UDP Firewall"
FULL_CONE_NAT = "Full Cone NAT"
RESTRICTED_NAT = "Restricted NAT"
RESTRICTED_PORT_NAT = "Restricted Port NAT"
SYMMETRIC_NAT = "Symmetric NAT"
CHANGED_ADDR_ERROR = "Error when testing on Changed-IP and Port"
@dataclasses.dataclass(frozen=True)
class StunInfo:
nat_type: StunNatType
src_ip: str
ext_ip: str
stun_host: str
stun_port: int
@dataclasses.dataclass(frozen=True)
class _StunAddress:
ip: str
port: int
@dataclasses.dataclass(frozen=True)
class _StunResponse:
ok: bool
ext: (_StunAddress | None) = dataclasses.field(default=None)
src: (_StunAddress | None) = dataclasses.field(default=None)
changed: (_StunAddress | None) = dataclasses.field(default=None)
# =====
class Stun:
# Partially based on https://github.com/JohnVillalovos/pystun
def __init__(
self,
host: str,
port: int,
timeout: float,
retries: int,
retries_delay: float,
) -> None:
self.__host = host
self.__port = port
self.__timeout = timeout
self.__retries = retries
self.__retries_delay = retries_delay
self.__sock: (socket.socket | None) = None
async def get_info(self, src_ip: str, src_port: int) -> StunInfo:
(family, _, _, _, addr) = socket.getaddrinfo(src_ip, src_port, type=socket.SOCK_DGRAM)[0]
nat_type = StunNatType.ERROR
ext_ip = ""
try:
with socket.socket(family, socket.SOCK_DGRAM) as self.__sock:
self.__sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
self.__sock.settimeout(self.__timeout)
self.__sock.bind(addr)
(nat_type, response) = await self.__get_nat_type(src_ip)
ext_ip = (response.ext.ip if response.ext is not None else "")
except Exception as err:
get_logger(0).error("Can't get STUN info: %s", tools.efmt(err))
finally:
self.__sock = None
return StunInfo(
nat_type=nat_type,
src_ip=src_ip,
ext_ip=ext_ip,
stun_host=self.__host,
stun_port=self.__port,
)
async def __get_nat_type(self, src_ip: str) -> tuple[StunNatType, _StunResponse]: # pylint: disable=too-many-return-statements
first = await self.__make_request("First probe", self.__host, b"")
if not first.ok:
return (StunNatType.BLOCKED, first)
request = struct.pack(">HHI", 0x0003, 0x0004, 0x00000006) # Change-Request
response = await self.__make_request("Change request [ext_ip == src_ip]", self.__host, request)
if first.ext is not None and first.ext.ip == src_ip:
if response.ok:
return (StunNatType.OPEN_INTERNET, response)
return (StunNatType.SYMMETRIC_UDP_FW, response)
if response.ok:
return (StunNatType.FULL_CONE_NAT, response)
if first.changed is None:
raise RuntimeError(f"Changed addr is None: {first}")
response = await self.__make_request("Change request [ext_ip != src_ip]", first.changed, b"")
if not response.ok:
return (StunNatType.CHANGED_ADDR_ERROR, response)
if response.ext == first.ext:
request = struct.pack(">HHI", 0x0003, 0x0004, 0x00000002)
response = await self.__make_request("Change port", first.changed.ip, request)
if response.ok:
return (StunNatType.RESTRICTED_NAT, response)
return (StunNatType.RESTRICTED_PORT_NAT, response)
return (StunNatType.SYMMETRIC_NAT, response)
async def __make_request(self, ctx: str, addr: (_StunAddress | str), request: bytes) -> _StunResponse:
# TODO: Support IPv6 and RFC 5389
# The first 4 bytes of the response are the Type (2) and Length (2)
# The 5th byte is Reserved
# The 6th byte is the Family: 0x01 = IPv4, 0x02 = IPv6
# The remaining bytes are the IP address. 32 bits for IPv4 or 128 bits for
# IPv6.
# More info at: https://tools.ietf.org/html/rfc3489#section-11.2.1
# And at: https://tools.ietf.org/html/rfc5389#section-15.1
if isinstance(addr, _StunAddress):
addr_t = (addr.ip, addr.port)
else: # str
addr_t = (addr, self.__port)
# https://datatracker.ietf.org/doc/html/rfc5389#section-6
trans_id = b"\x21\x12\xA4\x42" + secrets.token_bytes(12)
(response, error) = (b"", "")
for _ in range(self.__retries):
(response, error) = await self.__inner_make_request(trans_id, request, addr_t)
if not error:
break
await asyncio.sleep(self.__retries_delay)
if error:
get_logger(0).error("%s: Can't perform STUN request after %d retries; last error: %s",
ctx, self.__retries, error)
return _StunResponse(ok=False)
parsed: dict[str, _StunAddress] = {}
offset = 0
remaining = len(response)
while remaining > 0:
(attr_type, attr_len) = struct.unpack(">HH", response[offset : offset + 4]) # noqa: E203
offset += 4
field = {
0x0001: "ext", # MAPPED-ADDRESS
0x0020: "ext", # XOR-MAPPED-ADDRESS
0x0004: "src", # SOURCE-ADDRESS
0x0005: "changed", # CHANGED-ADDRESS
}.get(attr_type)
if field is not None:
parsed[field] = self.__parse_address(response[offset:], (trans_id if attr_type == 0x0020 else b""))
offset += attr_len
remaining -= (4 + attr_len)
return _StunResponse(ok=True, **parsed)
async def __inner_make_request(self, trans_id: bytes, request: bytes, addr: tuple[str, int]) -> tuple[bytes, str]:
assert self.__sock is not None
request = struct.pack(">HH", 0x0001, len(request)) + trans_id + request # Bind Request
try:
await aiotools.run_async(self.__sock.sendto, request, addr)
except Exception as err:
return (b"", f"Send error: {tools.efmt(err)}")
try:
response = (await aiotools.run_async(self.__sock.recvfrom, 2048))[0]
except Exception as err:
return (b"", f"Recv error: {tools.efmt(err)}")
(response_type, payload_len) = struct.unpack(">HH", response[:4])
if response_type != 0x0101:
return (b"", f"Invalid response type: {response_type:#06x}")
if trans_id != response[4:20]:
return (b"", "Transaction ID mismatch")
return (response[20 : 20 + payload_len], "") # noqa: E203
def __parse_address(self, data: bytes, trans_id: bytes) -> _StunAddress:
family = data[1]
port = struct.unpack(">H", self.__trans_xor(data[2:4], trans_id))[0]
if family == 0x01:
return _StunAddress(str(ipaddress.IPv4Address(self.__trans_xor(data[4:8], trans_id))), port)
elif family == 0x02:
return _StunAddress(str(ipaddress.IPv6Address(self.__trans_xor(data[4:20], trans_id))), port)
raise RuntimeError(f"Unknown family; received: {family}")
def __trans_xor(self, data: bytes, trans_id: bytes) -> bytes:
if len(trans_id) == 0:
return data
assert len(data) <= len(trans_id)
return bytes(byte ^ trans_id[index] for (index, byte) in enumerate(data))