117 lines
3.9 KiB
Python
117 lines
3.9 KiB
Python
"""Backport of aiohttp's AsyncResolver for Home Assistant.
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This is a backport of the AsyncResolver class from aiohttp 3.10.
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Before aiohttp 3.10, on system with IPv6 support, AsyncResolver would not fallback
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to providing A records when AAAA records were not available.
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Additionally, unlike the ThreadedResolver, AsyncResolver
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did not handle link-local addresses correctly.
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"""
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from __future__ import annotations
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import asyncio
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import socket
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import sys
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from typing import Any, TypedDict
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import aiodns
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from aiohttp.abc import AbstractResolver
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# This is a backport of https://github.com/aio-libs/aiohttp/pull/8270
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# This can be removed once aiohttp 3.10 is the minimum supported version.
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_NUMERIC_SOCKET_FLAGS = socket.AI_NUMERICHOST | socket.AI_NUMERICSERV
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_SUPPORTS_SCOPE_ID = sys.version_info >= (3, 9, 0)
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class ResolveResult(TypedDict):
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"""Resolve result.
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This is the result returned from an AbstractResolver's
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resolve method.
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:param hostname: The hostname that was provided.
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:param host: The IP address that was resolved.
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:param port: The port that was resolved.
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:param family: The address family that was resolved.
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:param proto: The protocol that was resolved.
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:param flags: The flags that were resolved.
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"""
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hostname: str
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host: str
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port: int
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family: int
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proto: int
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flags: int
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class AsyncResolver(AbstractResolver):
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"""Use the `aiodns` package to make asynchronous DNS lookups."""
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def __init__(self, *args: Any, **kwargs: Any) -> None:
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"""Initialize the resolver."""
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if aiodns is None:
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raise RuntimeError("Resolver requires aiodns library")
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self._loop = asyncio.get_running_loop()
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self._resolver = aiodns.DNSResolver(*args, loop=self._loop, **kwargs) # type: ignore[misc]
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async def resolve( # type: ignore[override]
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self, host: str, port: int = 0, family: int = socket.AF_INET
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) -> list[ResolveResult]:
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"""Resolve a host name to an IP address."""
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try:
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resp = await self._resolver.getaddrinfo(
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host,
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port=port,
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type=socket.SOCK_STREAM,
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family=family, # type: ignore[arg-type]
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flags=socket.AI_ADDRCONFIG,
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)
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except aiodns.error.DNSError as exc:
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msg = exc.args[1] if len(exc.args) >= 1 else "DNS lookup failed"
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raise OSError(msg) from exc
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hosts: list[ResolveResult] = []
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for node in resp.nodes:
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address: tuple[bytes, int] | tuple[bytes, int, int, int] = node.addr
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family = node.family
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if family == socket.AF_INET6:
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if len(address) > 3 and address[3] and _SUPPORTS_SCOPE_ID:
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# This is essential for link-local IPv6 addresses.
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# LL IPv6 is a VERY rare case. Strictly speaking, we should use
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# getnameinfo() unconditionally, but performance makes sense.
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result = await self._resolver.getnameinfo(
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(address[0].decode("ascii"), *address[1:]),
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_NUMERIC_SOCKET_FLAGS,
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)
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resolved_host = result.node
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else:
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resolved_host = address[0].decode("ascii")
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port = address[1]
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else: # IPv4
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assert family == socket.AF_INET
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resolved_host = address[0].decode("ascii")
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port = address[1]
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hosts.append(
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ResolveResult(
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hostname=host,
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host=resolved_host,
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port=port,
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family=family,
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proto=0,
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flags=_NUMERIC_SOCKET_FLAGS,
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)
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)
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if not hosts:
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raise OSError("DNS lookup failed")
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return hosts
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async def close(self) -> None:
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"""Close the resolver."""
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self._resolver.cancel()
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