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qemu/python-aqmp-add-socket-bind-step-to-lega.patch
2022-05-27 12:52:53 +00:00

136 lines
4.8 KiB
Diff

From: John Snow <jsnow@redhat.com>
Date: Mon, 31 Jan 2022 23:11:34 -0500
Subject: python/aqmp: add socket bind step to legacy.py
Git-commit: b0b662bb2b340d63529672b5bdae596a6243c4d0
The synchronous QMP library would bind to the server address during
__init__(). The new library delays this to the accept() call, because
binding occurs inside of the call to start_[unix_]server(), which is an
async method -- so it cannot happen during __init__ anymore.
Python 3.7+ adds the ability to create the server (and thus the bind()
call) and begin the active listening in separate steps, but we don't
have that functionality in 3.6, our current minimum.
Therefore ... Add a temporary workaround that allows the synchronous
version of the client to bind the socket in advance, guaranteeing that
there will be a UNIX socket in the filesystem ready for the QEMU client
to connect to without a race condition.
(Yes, it's a bit ugly. Fixing it more nicely will have to wait until our
minimum Python version is 3.7+.)
Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Message-id: 20220201041134.1237016-5-jsnow@redhat.com
Signed-off-by: John Snow <jsnow@redhat.com>
Signed-off-by: Li Zhang <lizhang@suse.de>
---
python/qemu/aqmp/legacy.py | 3 +++
python/qemu/aqmp/protocol.py | 41 +++++++++++++++++++++++++++++++++---
2 files changed, 41 insertions(+), 3 deletions(-)
diff --git a/python/qemu/aqmp/legacy.py b/python/qemu/aqmp/legacy.py
index 0890f95b16875ecb815ed4560bc7..6baa5f3409a6b459c67097d3c2a0 100644
--- a/python/qemu/aqmp/legacy.py
+++ b/python/qemu/aqmp/legacy.py
@@ -56,6 +56,9 @@ class QEMUMonitorProtocol(qemu.qmp.QEMUMonitorProtocol):
self._address = address
self._timeout: Optional[float] = None
+ if server:
+ self._aqmp._bind_hack(address) # pylint: disable=protected-access
+
_T = TypeVar('_T')
def _sync(
diff --git a/python/qemu/aqmp/protocol.py b/python/qemu/aqmp/protocol.py
index 50e973c2f2dc9c5fa759380ab3e9..33358f5cd72b61bd060b8dea6091 100644
--- a/python/qemu/aqmp/protocol.py
+++ b/python/qemu/aqmp/protocol.py
@@ -15,6 +15,7 @@ from asyncio import StreamReader, StreamWriter
from enum import Enum
from functools import wraps
import logging
+import socket
from ssl import SSLContext
from typing import (
Any,
@@ -238,6 +239,9 @@ class AsyncProtocol(Generic[T]):
self._runstate = Runstate.IDLE
self._runstate_changed: Optional[asyncio.Event] = None
+ # Workaround for bind()
+ self._sock: Optional[socket.socket] = None
+
def __repr__(self) -> str:
cls_name = type(self).__name__
tokens = []
@@ -427,6 +431,34 @@ class AsyncProtocol(Generic[T]):
else:
await self._do_connect(address, ssl)
+ def _bind_hack(self, address: Union[str, Tuple[str, int]]) -> None:
+ """
+ Used to create a socket in advance of accept().
+
+ This is a workaround to ensure that we can guarantee timing of
+ precisely when a socket exists to avoid a connection attempt
+ bouncing off of nothing.
+
+ Python 3.7+ adds a feature to separate the server creation and
+ listening phases instead, and should be used instead of this
+ hack.
+ """
+ if isinstance(address, tuple):
+ family = socket.AF_INET
+ else:
+ family = socket.AF_UNIX
+
+ sock = socket.socket(family, socket.SOCK_STREAM)
+ sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
+
+ try:
+ sock.bind(address)
+ except:
+ sock.close()
+ raise
+
+ self._sock = sock
+
@upper_half
async def _do_accept(self, address: SocketAddrT,
ssl: Optional[SSLContext] = None) -> None:
@@ -464,24 +496,27 @@ class AsyncProtocol(Generic[T]):
if isinstance(address, tuple):
coro = asyncio.start_server(
_client_connected_cb,
- host=address[0],
- port=address[1],
+ host=None if self._sock else address[0],
+ port=None if self._sock else address[1],
ssl=ssl,
backlog=1,
limit=self._limit,
+ sock=self._sock,
)
else:
coro = asyncio.start_unix_server(
_client_connected_cb,
- path=address,
+ path=None if self._sock else address,
ssl=ssl,
backlog=1,
limit=self._limit,
+ sock=self._sock,
)
server = await coro # Starts listening
await connected.wait() # Waits for the callback to fire (and finish)
assert server is None
+ self._sock = None
self.logger.debug("Connection accepted.")