From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.0 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 7CAC2C433E0 for ; Sat, 30 May 2020 09:28:27 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 447EB208E4 for ; Sat, 30 May 2020 09:28:27 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="b2FAE5bs" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 447EB208E4 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:40070 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1jexn0-0001CG-I1 for qemu-devel@archiver.kernel.org; Sat, 30 May 2020 05:28:26 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:49634) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1jexm2-0000U1-KJ for qemu-devel@nongnu.org; Sat, 30 May 2020 05:27:30 -0400 Received: from us-smtp-delivery-1.mimecast.com ([207.211.31.120]:46191 helo=us-smtp-1.mimecast.com) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA1:256) (Exim 4.90_1) (envelope-from ) id 1jexm0-0000Sr-6S for qemu-devel@nongnu.org; Sat, 30 May 2020 05:27:25 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1590830842; 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=QNCBlcfXesRsi7EHYn/qiLEFZSVhVTbggu1BTv3xExs=; b=b2FAE5bsmCQfP6gCz0OWSG2qHMPcZ3jzyxEJsMOXWFig1iw7fJ0KbityaiRXoPWJUDPFYY u9ix3/DQ0M7PGnh4mE9mejEjHhMq8UWsYBCwh8WyyrZL7c4jTokFDDw5TdMQNMDsLeJZlJ 9vgHpC/rPvW+PO0dCYfbtUMNA0wLuBg= 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-91-divcMtUfP3iseg-lNCdiTw-1; Sat, 30 May 2020 05:27:20 -0400 X-MC-Unique: divcMtUfP3iseg-lNCdiTw-1 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 ECEA7107ACCA; Sat, 30 May 2020 09:27:18 +0000 (UTC) Received: from localhost (ovpn-112-79.ams2.redhat.com [10.36.112.79]) by smtp.corp.redhat.com (Postfix) with ESMTP id 064A978366; Sat, 30 May 2020 09:27:15 +0000 (UTC) Date: Sat, 30 May 2020 10:27:15 +0100 From: "Richard W.M. Jones" To: Eric Wheeler Subject: Re: [Libguestfs] Provide NBD via Browser over Websockets Message-ID: <20200530092715.GX3888@redhat.com> References: <20200528090443.GN7304@redhat.com> <20200529093744.GS3888@redhat.com> <13571029-5bf4-2dfa-6879-0ad2642afb3f@redhat.com> <20200529135042.GJ2755532@redhat.com> <20200529141315.GU3888@redhat.com> MIME-Version: 1.0 In-Reply-To: User-Agent: Mutt/1.5.21 (2010-09-15) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: 8bit Content-Disposition: inline Received-SPF: pass client-ip=207.211.31.120; envelope-from=rjones@redhat.com; helo=us-smtp-1.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/05/30 05:27:22 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 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_NONE=-0.0001, RCVD_IN_MSPIKE_H3=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_PASS=-0.001, URIBL_BLOCKED=0.001 autolearn=_AUTOLEARN 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: Daniel =?iso-8859-1?Q?P=2E_Berrang=E9?= , QEMU , nbd@other.debian.org, Nir Soffer , libguestfs Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Fri, May 29, 2020 at 09:08:29PM +0000, Eric Wheeler wrote: > On Fri, 29 May 2020, Richard W.M. Jones wrote: > > On Fri, May 29, 2020 at 08:58:06AM -0500, Eric Blake wrote: > > > On 5/29/20 8:50 AM, Daniel P. Berrangé wrote: > > > > > > >>>(2) You need to persuade qemu's NBD client to read from a WebSocket. > > > >>>I didn't really know anything about WebSockets until today but it > > > >>>seems as if they are a full-duplex protocol layered on top of HTTP [a]. > > > >>>Is there a WebSocket proxy that turns WS into plain TCP (a bit like > > > >>>stunnel)? Google suggests [b]. > > > >>> > > > >>>[a] https://en.wikipedia.org/wiki/WebSocket#Protocol_handshake > > > >>>[b] https://github.com/novnc/websockify > > > >> > > > >>qemu already knows how to connect as a client to websockets; Dan Berrange > > > >>knows more about that setup. I suspect it would not be too difficult to > > > >>teach the qemu NBD client code to use a WebSocket instead of a Unix or TCP > > > >>socket as its data source. > > > > > > > >Actually the inverse. The QIOChannelWebsocket impl is only the server > > > >side of the problem, as used by QEMU's VNC server. We've never implemented > > > >the client side. There is nothing especially stopping us doing that - just > > > >needs someone motivated with time to work on it. > > > > > > In the meantime, you may still be able to set up something like: > > > > > > local machine: > > > iso -> NBD server -> Unix socket -> websockify -> WebSocket > > > > I guess the idea is to have a zero-install solution for the browser. > > As I said in the email earlier this is very common for IPMI-type > > remote access to blade servers and in my experience is implemented > > using a Java applet and a proprietary protocol terminated at the BMC > > (which then emulates a virtual CDROM to the server). There are some > > HP blade servers on Red Hat's internal Beaker instance where you can > > play with this. For qemu we wouldn't need to invent a new protocol > > when NBD is available and already implemented (albeit not yet on top > > of WebSockets). > > > > The NBD server must run inside the browser and therefore be either > > written from scratch in Javascript, or an existing server > > cross-compiled to WASM (if that is possible - I don't really know). > > Interesting idea about WASM. I'll see if I can build one of the simple > nbd servers that are around. Not sure how to link it to the JS file IO, > however. After reading a bit about compiling to WebSockets it sounds like you can cross-compile a C program, but there's no library support at all. IOW to port an existing server you'd have to implement enough of POSIX to make it work. nbdkit has a liberal license deliberately to make it possible to chop it up and incorporate it into completely forked codebases (nbdkit is a plot to make NBD more popular). But since NBD is pretty simple, a fresh Javascript server might be easier, especially if you stick to only implementing reads. Rich. -- Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones Read my programming and virtualization blog: http://rwmj.wordpress.com virt-top is 'top' for virtual machines. Tiny program with many powerful monitoring features, net stats, disk stats, logging, etc. http://people.redhat.com/~rjones/virt-top