From nobody Sun Dec 14 08:03:07 2025 Delivered-To: importer@patchew.org Authentication-Results: mx.zohomail.com; dkim=fail; spf=pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org; dmarc=fail(p=none dis=none) header.from=redhat.com Return-Path: Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) by mx.zohomail.com with SMTPS id 1632771398540351.60233074390817; Mon, 27 Sep 2021 12:36:38 -0700 (PDT) Received: from localhost ([::1]:54072 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1mUwQX-0007tH-Ee for importer@patchew.org; Mon, 27 Sep 2021 15:36:37 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:58102) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1mUwIm-00060w-1i for qemu-devel@nongnu.org; Mon, 27 Sep 2021 15:28:37 -0400 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:59684) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1mUwIk-00087Y-0N for qemu-devel@nongnu.org; Mon, 27 Sep 2021 15:28:35 -0400 Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-103-S6BQvOI9N5yE1BQHJGae-Q-1; Mon, 27 Sep 2021 15:28:30 -0400 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 8DB411084683; Mon, 27 Sep 2021 19:28:29 +0000 (UTC) Received: from scv.redhat.com (unknown [10.22.9.55]) by smtp.corp.redhat.com (Postfix) with ESMTP id E11C760871; Mon, 27 Sep 2021 19:28:27 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1632770913; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=OJKA3ZuhCRHrDkdUwuwnHQea0qchPw+I2YBp1BnrWnc=; b=Ylnij/jV8uMFj08BVw5/Cp9zGJEXusVRfxWI2ZcCuzBEWFIc9lstNByVb1Gav5whfSEOw/ OOz2OMk/p4zp048jnpBb+sMhjPNgMLNpMoXYMNMP2ahzZtOgonlKR9kl3gzIPpIq6i0+hR c4lUytqOJuLC+SogyFFA0y4BFuzwteU= X-MC-Unique: S6BQvOI9N5yE1BQHJGae-Q-1 From: John Snow To: qemu-devel@nongnu.org Subject: [PULL 17/32] python/aqmp: add QMP protocol support Date: Mon, 27 Sep 2021 15:24:58 -0400 Message-Id: <20210927192513.744199-18-jsnow@redhat.com> In-Reply-To: <20210927192513.744199-1-jsnow@redhat.com> References: <20210927192513.744199-1-jsnow@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=jsnow@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Transfer-Encoding: quoted-printable Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Received-SPF: pass client-ip=216.205.24.124; envelope-from=jsnow@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -27 X-Spam_score: -2.8 X-Spam_bar: -- X-Spam_report: (-2.8 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H2=-0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Peter Maydell , Thomas Huth , Daniel Berrange , Eduardo Habkost , =?UTF-8?q?Alex=20Benn=C3=A9e?= , Markus Armbruster , Wainer dos Santos Moschetta , =?UTF-8?q?Philippe=20Mathieu-Daud=C3=A9?= , Willian Rampazzo , Cleber Rosa , John Snow Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: "Qemu-devel" X-ZohoMail-DKIM: fail (Header signature does not verify) X-ZM-MESSAGEID: 1632771400049100003 Content-Type: text/plain; charset="utf-8" The star of our show! Add most of the QMP protocol, sans support for actually executing commands. No problem, that happens in the next several commits. Signed-off-by: John Snow Message-id: 20210915162955.333025-18-jsnow@redhat.com Signed-off-by: John Snow --- python/qemu/aqmp/__init__.py | 2 + python/qemu/aqmp/qmp_client.py | 264 +++++++++++++++++++++++++++++++++ 2 files changed, 266 insertions(+) create mode 100644 python/qemu/aqmp/qmp_client.py diff --git a/python/qemu/aqmp/__init__.py b/python/qemu/aqmp/__init__.py index 829166a2e2e..d975c752eaa 100644 --- a/python/qemu/aqmp/__init__.py +++ b/python/qemu/aqmp/__init__.py @@ -25,11 +25,13 @@ from .events import EventListener from .message import Message from .protocol import ConnectError, Runstate, StateError +from .qmp_client import QMPClient =20 =20 # The order of these fields impact the Sphinx documentation order. __all__ =3D ( # Classes, most to least important + 'QMPClient', 'Message', 'EventListener', 'Runstate', diff --git a/python/qemu/aqmp/qmp_client.py b/python/qemu/aqmp/qmp_client.py new file mode 100644 index 00000000000..000ff59c7a7 --- /dev/null +++ b/python/qemu/aqmp/qmp_client.py @@ -0,0 +1,264 @@ +""" +QMP Protocol Implementation + +This module provides the `QMPClient` class, which can be used to connect +and send commands to a QMP server such as QEMU. The QMP class can be +used to either connect to a listening server, or used to listen and +accept an incoming connection from that server. +""" + +import logging +from typing import ( + Dict, + List, + Mapping, + Optional, +) + +from .error import ProtocolError +from .events import Events +from .message import Message +from .models import Greeting +from .protocol import AsyncProtocol +from .util import ( + bottom_half, + exception_summary, + pretty_traceback, + upper_half, +) + + +class _WrappedProtocolError(ProtocolError): + """ + Abstract exception class for Protocol errors that wrap an Exception. + + :param error_message: Human-readable string describing the error. + :param exc: The root-cause exception. + """ + def __init__(self, error_message: str, exc: Exception): + super().__init__(error_message) + self.exc =3D exc + + def __str__(self) -> str: + return f"{self.error_message}: {self.exc!s}" + + +class GreetingError(_WrappedProtocolError): + """ + An exception occurred during the Greeting phase. + + :param error_message: Human-readable string describing the error. + :param exc: The root-cause exception. + """ + + +class NegotiationError(_WrappedProtocolError): + """ + An exception occurred during the Negotiation phase. + + :param error_message: Human-readable string describing the error. + :param exc: The root-cause exception. + """ + + +class QMPClient(AsyncProtocol[Message], Events): + """ + Implements a QMP client connection. + + QMP can be used to establish a connection as either the transport + client or server, though this class always acts as the QMP client. + + :param name: Optional nickname for the connection, used for logging. + + Basic script-style usage looks like this:: + + qmp =3D QMPClient('my_virtual_machine_name') + await qmp.connect(('127.0.0.1', 1234)) + ... + res =3D await qmp.execute('block-query') + ... + await qmp.disconnect() + + Basic async client-style usage looks like this:: + + class Client: + def __init__(self, name: str): + self.qmp =3D QMPClient(name) + + async def watch_events(self): + try: + async for event in self.qmp.events: + print(f"Event: {event['event']}") + except asyncio.CancelledError: + return + + async def run(self, address=3D'/tmp/qemu.socket'): + await self.qmp.connect(address) + asyncio.create_task(self.watch_events()) + await self.qmp.runstate_changed.wait() + await self.disconnect() + + See `aqmp.events` for more detail on event handling patterns. + """ + #: Logger object used for debugging messages. + logger =3D logging.getLogger(__name__) + + # Read buffer limit; large enough to accept query-qmp-schema + _limit =3D (256 * 1024) + + def __init__(self, name: Optional[str] =3D None) -> None: + super().__init__(name) + Events.__init__(self) + + #: Whether or not to await a greeting after establishing a connect= ion. + self.await_greeting: bool =3D True + + #: Whether or not to perform capabilities negotiation upon connect= ion. + #: Implies `await_greeting`. + self.negotiate: bool =3D True + + # Cached Greeting, if one was awaited. + self._greeting: Optional[Greeting] =3D None + + @upper_half + async def _establish_session(self) -> None: + """ + Initiate the QMP session. + + Wait for the QMP greeting and perform capabilities negotiation. + + :raise GreetingError: When the greeting is not understood. + :raise NegotiationError: If the negotiation fails. + :raise EOFError: When the server unexpectedly hangs up. + :raise OSError: For underlying stream errors. + """ + if self.await_greeting or self.negotiate: + self._greeting =3D await self._get_greeting() + + if self.negotiate: + await self._negotiate() + + # This will start the reader/writers: + await super()._establish_session() + + @upper_half + async def _get_greeting(self) -> Greeting: + """ + :raise GreetingError: When the greeting is not understood. + :raise EOFError: When the server unexpectedly hangs up. + :raise OSError: For underlying stream errors. + + :return: the Greeting object given by the server. + """ + self.logger.debug("Awaiting greeting ...") + + try: + msg =3D await self._recv() + return Greeting(msg) + except (ProtocolError, KeyError, TypeError) as err: + emsg =3D "Did not understand Greeting" + self.logger.error("%s: %s", emsg, exception_summary(err)) + self.logger.debug("%s:\n%s\n", emsg, pretty_traceback()) + raise GreetingError(emsg, err) from err + except BaseException as err: + # EOFError, OSError, or something unexpected. + emsg =3D "Failed to receive Greeting" + self.logger.error("%s: %s", emsg, exception_summary(err)) + self.logger.debug("%s:\n%s\n", emsg, pretty_traceback()) + raise + + @upper_half + async def _negotiate(self) -> None: + """ + Perform QMP capabilities negotiation. + + :raise NegotiationError: When negotiation fails. + :raise EOFError: When the server unexpectedly hangs up. + :raise OSError: For underlying stream errors. + """ + self.logger.debug("Negotiating capabilities ...") + + arguments: Dict[str, List[str]] =3D {'enable': []} + if self._greeting and 'oob' in self._greeting.QMP.capabilities: + arguments['enable'].append('oob') + msg =3D self.make_execute_msg('qmp_capabilities', arguments=3Dargu= ments) + + # It's not safe to use execute() here, because the reader/writers + # aren't running. AsyncProtocol *requires* that a new session + # does not fail after the reader/writers are running! + try: + await self._send(msg) + reply =3D await self._recv() + assert 'return' in reply + assert 'error' not in reply + except (ProtocolError, AssertionError) as err: + emsg =3D "Negotiation failed" + self.logger.error("%s: %s", emsg, exception_summary(err)) + self.logger.debug("%s:\n%s\n", emsg, pretty_traceback()) + raise NegotiationError(emsg, err) from err + except BaseException as err: + # EOFError, OSError, or something unexpected. + emsg =3D "Negotiation failed" + self.logger.error("%s: %s", emsg, exception_summary(err)) + self.logger.debug("%s:\n%s\n", emsg, pretty_traceback()) + raise + + @bottom_half + async def _on_message(self, msg: Message) -> None: + """ + Add an incoming message to the appropriate queue/handler. + """ + # Incoming messages are not fully parsed/validated here; + # do only light peeking to know how to route the messages. + + if 'event' in msg: + await self._event_dispatch(msg) + return + + # Below, we assume everything left is an execute/exec-oob response. + # ... Which we'll implement in the next commit! + + @upper_half + @bottom_half + async def _do_recv(self) -> Message: + """ + :raise OSError: When a stream error is encountered. + :raise EOFError: When the stream is at EOF. + :raise ProtocolError: + When the Message is not understood. + See also `Message._deserialize`. + + :return: A single QMP `Message`. + """ + msg_bytes =3D await self._readline() + msg =3D Message(msg_bytes, eager=3DTrue) + return msg + + @upper_half + @bottom_half + def _do_send(self, msg: Message) -> None: + """ + :raise ValueError: JSON serialization failure + :raise TypeError: JSON serialization failure + :raise OSError: When a stream error is encountered. + """ + assert self._writer is not None + self._writer.write(bytes(msg)) + + @classmethod + def make_execute_msg(cls, cmd: str, + arguments: Optional[Mapping[str, object]] =3D Non= e, + oob: bool =3D False) -> Message: + """ + Create an executable message to be sent later. + + :param cmd: QMP command name. + :param arguments: Arguments (if any). Must be JSON-serializable. + :param oob: If `True`, execute "out of band". + + :return: An executable QMP `Message`. + """ + msg =3D Message({'exec-oob' if oob else 'execute': cmd}) + if arguments is not None: + msg['arguments'] =3D arguments + return msg --=20 2.31.1