From nobody Mon Feb 9 00:42:24 2026 Delivered-To: importer@patchew.org Received-SPF: pass (zoho.com: domain of gnu.org designates 208.118.235.17 as permitted sender) client-ip=208.118.235.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Authentication-Results: mx.zohomail.com; spf=pass (zoho.com: domain of gnu.org designates 208.118.235.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org Return-Path: Received: from lists.gnu.org (lists.gnu.org [208.118.235.17]) by mx.zohomail.com with SMTPS id 1510024081975925.3056156690723; Mon, 6 Nov 2017 19:08:01 -0800 (PST) Received: from localhost ([::1]:51213 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1eBuF5-0002j8-6L for importer@patchew.org; Mon, 06 Nov 2017 22:07:59 -0500 Received: from eggs.gnu.org ([2001:4830:134:3::10]:37722) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1eBuAB-0007e5-IE for qemu-devel@nongnu.org; Mon, 06 Nov 2017 22:02:56 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1eBuAA-0003Wo-A8 for qemu-devel@nongnu.org; Mon, 06 Nov 2017 22:02:55 -0500 Received: from mx1.redhat.com ([209.132.183.28]:58164) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1eBuA7-0003Ug-E8; Mon, 06 Nov 2017 22:02:51 -0500 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 72C5683F3E; Tue, 7 Nov 2017 03:02:50 +0000 (UTC) Received: from red.redhat.com (ovpn-125-14.rdu2.redhat.com [10.10.125.14]) by smtp.corp.redhat.com (Postfix) with ESMTP id 62453600D3; Tue, 7 Nov 2017 03:02:49 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mx1.redhat.com 72C5683F3E Authentication-Results: ext-mx03.extmail.prod.ext.phx2.redhat.com; dmarc=none (p=none dis=none) header.from=redhat.com Authentication-Results: ext-mx03.extmail.prod.ext.phx2.redhat.com; spf=fail smtp.mailfrom=eblake@redhat.com From: Eric Blake To: qemu-devel@nongnu.org Date: Mon, 6 Nov 2017 21:02:36 -0600 Message-Id: <20171107030236.23633-9-eblake@redhat.com> In-Reply-To: <20171107030236.23633-1-eblake@redhat.com> References: <20171107030236.23633-1-eblake@redhat.com> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.27]); Tue, 07 Nov 2017 03:02:50 +0000 (UTC) X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 209.132.183.28 Subject: [Qemu-devel] [PATCH 8/8] nbd/server: Fix structured read of length 0 X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: pbonzini@redhat.com, vsementsov@virtuozzo.com, qemu-block@nongnu.org Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: "Qemu-devel" X-ZohoMail: RSF_0 Z_629925259 SPT_0 Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" The NBD spec is being clarified that a read of length 0 should not be attempted by a compliant client; but that a server must handle it correctly. However, it also implies that NBD_REPLY_TYPE_OFFSET_DATA must have a non-zero payload length, which means that we must either give an error or use a no-op REPLY_TYPE_NONE in response to a zero-length read, so that we don't trip up any clients that might kill the connection if we send a data chunk without data. Signed-off-by: Eric Blake --- nbd/server.c | 21 ++++++++++++++++++++- nbd/trace-events | 1 + 2 files changed, 21 insertions(+), 1 deletion(-) diff --git a/nbd/server.c b/nbd/server.c index 6ebb7d9c2e..df771fd42f 100644 --- a/nbd/server.c +++ b/nbd/server.c @@ -1273,6 +1273,21 @@ static inline void set_be_chunk(NBDStructuredReplyCh= unk *chunk, uint16_t flags, stl_be_p(&chunk->length, length); } +static int coroutine_fn nbd_co_send_structured_done(NBDClient *client, + uint64_t handle, + Error **errp) +{ + NBDStructuredReplyChunk chunk; + struct iovec iov[] =3D { + {.iov_base =3D &chunk, .iov_len =3D sizeof(chunk)}, + }; + + trace_nbd_co_send_structured_done(handle); + set_be_chunk(&chunk, NBD_REPLY_FLAG_DONE, NBD_REPLY_TYPE_NONE, handle,= 0); + + return nbd_co_send_iov(client, iov, 1, errp); +} + static int coroutine_fn nbd_co_send_structured_read(NBDClient *client, uint64_t handle, uint64_t offset, @@ -1286,6 +1301,7 @@ static int coroutine_fn nbd_co_send_structured_read(N= BDClient *client, {.iov_base =3D data, .iov_len =3D size} }; + assert(size); trace_nbd_co_send_structured_read(handle, offset, data, size); set_be_chunk(&chunk.h, NBD_REPLY_FLAG_DONE, NBD_REPLY_TYPE_OFFSET_DATA, handle, sizeof(chunk) - sizeof(chunk.h) + size); @@ -1544,10 +1560,13 @@ reply: if (ret < 0) { ret =3D nbd_co_send_structured_error(req->client, request.hand= le, -ret, msg, &local_err); - } else { + } else if (reply_data_len) { ret =3D nbd_co_send_structured_read(req->client, request.handl= e, request.from, req->data, reply_data_len, &local_err); + } else { + ret =3D nbd_co_send_structured_done(req->client, request.handl= e, + &local_err); } } else { ret =3D nbd_co_send_simple_reply(req->client, request.handle, diff --git a/nbd/trace-events b/nbd/trace-events index bbc75f6414..92568edce5 100644 --- a/nbd/trace-events +++ b/nbd/trace-events @@ -55,6 +55,7 @@ nbd_receive_request(uint32_t magic, uint16_t flags, uint1= 6_t type, uint64_t from nbd_blk_aio_attached(const char *name, void *ctx) "Export %s: Attaching cl= ients to AIO context %p\n" nbd_blk_aio_detach(const char *name, void *ctx) "Export %s: Detaching clie= nts from AIO context %p\n" nbd_co_send_simple_reply(uint64_t handle, uint32_t error, const char *errn= ame, int len) "Send simple reply: handle =3D %" PRIu64 ", error =3D %" PRIu= 32 " (%s), len =3D %d" +nbd_co_send_structured_done(uint64_t handle) "Send structured reply done: = handle =3D %" PRIu64 nbd_co_send_structured_read(uint64_t handle, uint64_t offset, void *data, = size_t size) "Send structured read data reply: handle =3D %" PRIu64 ", offs= et =3D %" PRIu64 ", data =3D %p, len =3D %zu" nbd_co_send_structured_error(uint64_t handle, int err, const char *errname= , const char *msg) "Send structured error reply: handle =3D %" PRIu64 ", er= ror =3D %d (%s), msg =3D '%s'" nbd_co_receive_request_decode_type(uint64_t handle, uint16_t type, const c= har *name) "Decoding type: handle =3D %" PRIu64 ", type =3D %" PRIu16 " (%s= )" --=20 2.13.6