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=-4.0 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no 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 2D129C433DF for ; Tue, 4 Aug 2020 14:20:41 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1A7D4208A9 for ; Tue, 4 Aug 2020 14:20:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728493AbgHDOUh (ORCPT ); Tue, 4 Aug 2020 10:20:37 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55998 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725932AbgHDOUd (ORCPT ); Tue, 4 Aug 2020 10:20:33 -0400 Received: from orbyte.nwl.cc (orbyte.nwl.cc [IPv6:2001:41d0:e:133a::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D4211C06174A for ; Tue, 4 Aug 2020 07:20:32 -0700 (PDT) Received: from n0-1 by orbyte.nwl.cc with local (Exim 4.94) (envelope-from ) id 1k2xnn-0004o7-BS; Tue, 04 Aug 2020 16:20:27 +0200 Date: Tue, 4 Aug 2020 16:20:27 +0200 From: Phil Sutter To: Pablo Neira Ayuso Cc: "Jose M. Guisado" , netfilter-devel@vger.kernel.org, erig@erig.me Subject: Re: [PATCH nft v4] src: enable json echo output when reading native syntax Message-ID: <20200804142027.GX13697@orbyte.nwl.cc> Mail-Followup-To: Phil Sutter , Pablo Neira Ayuso , "Jose M. Guisado" , netfilter-devel@vger.kernel.org, erig@erig.me References: <20200731104944.21384-1-guigom@riseup.net> <20200804103846.58872-1-guigom@riseup.net> <20200804123744.GV13697@orbyte.nwl.cc> <87971ac3-ed9c-9923-ca3f-df6dfb8b94d9@riseup.net> <20200804131423.GW13697@orbyte.nwl.cc> <6bf33b55-6439-0ae5-9dbf-e18c01969d42@riseup.net> <20200804140454.GA6002@salvia> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200804140454.GA6002@salvia> Sender: netfilter-devel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netfilter-devel@vger.kernel.org Hi, On Tue, Aug 04, 2020 at 04:04:54PM +0200, Pablo Neira Ayuso wrote: > On Tue, Aug 04, 2020 at 03:44:25PM +0200, Jose M. Guisado wrote: > > Hi Phil. > > > > On 4/8/20 15:14, Phil Sutter wrote: > > > Hi, > > > > > > On Tue, Aug 04, 2020 at 03:05:25PM +0200, Jose M. Guisado wrote: > > > > On 4/8/20 14:37, Phil Sutter wrote: > > > > > Why not just: > > > > > > > > > > --- a/src/monitor.c > > > > > +++ b/src/monitor.c > > > > > @@ -922,8 +922,11 @@ int netlink_echo_callback(const struct nlmsghdr *nlh, void *data) > > > > > if (!nft_output_echo(&echo_monh.ctx->nft->output)) > > > > > return MNL_CB_OK; > > > > > - if (nft_output_json(&ctx->nft->output)) > > > > > - return json_events_cb(nlh, &echo_monh); > > > > > + if (nft_output_json(&ctx->nft->output)) { > > > > > + if (ctx->nft->json_root) > > > > > + return json_events_cb(nlh, &echo_monh); > > > > > + echo_monh.format = NFTNL_OUTPUT_JSON; > > > > > + } > > > > > return netlink_events_cb(nlh, &echo_monh); > > > > > } > > > > > > > > > > At a first glance, this seems to work just fine. > > > > > > > > > > Cheers, Phil > > > > > > > > This does not output anything on my machine. This is because json_echo > > > > is not initialized before netlink_echo_callback. > > > > > > Please try my diff above on upstream's master without your changes. In > > > the tree I did above changes, no symbol named 'json_echo' exists. > > > > > > Cheers, Phil > > > > Just tested it, it works great on my machine. As it outputs the same that > > would a running nft monitor. Thanks for validating. > > I'm imagining this is preferred if there's no need having the json commands > > in the output be wrapped inside list of a single json object with its > > metainfo. That's the main difference with your patch. Yes, 'nft -j monitor' output has always been like this. Given that monitor potentially runs for a while and picks up multiple distinct ruleset changes, I wonder how it *should* behave. > If it's not wrapped by the top-level nftables root then this is > unparseable. We could change monitor code to add the wrapping "nftables" object to every line printed: --- a/src/json.c +++ b/src/json.c @@ -1857,7 +1857,8 @@ int do_command_list_json(struct netlink_ctx *ctx, struct cmd *cmd) static void monitor_print_json(struct netlink_mon_handler *monh, const char *cmd, json_t *obj) { - obj = json_pack("{s:o}", cmd, obj); + obj = json_pack("{s:[o, {s:o}]}", "nftables", + generate_json_metainfo(), cmd, obj); json_dumpf(obj, monh->ctx->nft->output.output_fp, 0); json_decref(obj); } Cheers, Phil