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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 65C4FC54EE9 for ; Fri, 2 Sep 2022 07:15:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235438AbiIBHPg (ORCPT ); Fri, 2 Sep 2022 03:15:36 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35990 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231544AbiIBHPc (ORCPT ); Fri, 2 Sep 2022 03:15:32 -0400 Received: from gnuweeb.org (gnuweeb.org [51.81.211.47]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 9200C27CFE for ; Fri, 2 Sep 2022 00:15:31 -0700 (PDT) Received: from localhost.localdomain (unknown [182.2.70.226]) by gnuweeb.org (Postfix) with ESMTPSA id 817AB80C57; Fri, 2 Sep 2022 07:15:27 +0000 (UTC) X-GW-Data: lPqxHiMPbJw1wb7CM9QUryAGzr0yq5atzVDdxTR0iA== DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=gnuweeb.org; s=default; t=1662102931; bh=lZw4entFoarpqtxNEsuI3QpY8fUls6MsgylWRSF/gFQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=JJwKH9iLze8+Cv7ToS8KMYgZvEubbfTc89gFwj8+CvMZG8DhDdXYM4zXBV4T/rbq3 C8VaOWpFEGB+U6Y61iEqEbWJBHZlJUrPFoReMTbFFj1CcPVEV2lt+BpFT8jFA7Zm7f /wY8aqhK4grXqcK8wJvK2DIewMhG1NZx1oBslp2B2emO44US0ADmPKMenhr4erIfuM nCO2uYZkEbwiEcxm6EOSChJp8ZPWjp4+aR6VloHQZRZqs2YzlhusghEQClBnoPALMP dYM69mjs6SdBP/rAOyAe7G2DCurSzjDVw+U1zrBJjxuf4B4+o5pBHm4KnUcvS3+cIu eYfuqd6Aa0KjQ== From: Ammar Faizi To: Jens Axboe Cc: Ammar Faizi , Dylan Yudaken , Facebook Kernel Team , Pavel Begunkov , io-uring Mailing List , GNU/Weeb Mailing List , Kanna Scarlet , Muhammad Rizki , Alviro Iskandar Setiawan Subject: [PATCH liburing v2 01/12] test/helpers: Add `t_bind_ephemeral_port()` function Date: Fri, 2 Sep 2022 14:14:54 +0700 Message-Id: <20220902071153.3168814-2-ammar.faizi@intel.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20220902071153.3168814-1-ammar.faizi@intel.com> References: <20220902071153.3168814-1-ammar.faizi@intel.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: io-uring@vger.kernel.org From: Ammar Faizi This is a prep patch to fix an intermittent issue with the port number. We have many places where we need to bind() a socket to any unused port number. To achieve that, the current approach does one of the following mechanisms: 1) Randomly brute force the port number until the bind() syscall succeeds. 2) Use a static port at compile time (randomly chosen too). This is not reliable and it results in an intermittent issue (test fails when the selected port is in use). Setting @addr->sin_port to zero on a bind() syscall lets the kernel choose a port number that is not in use. The caller then can know the port number to be bound by invoking a getsockname() syscall after bind() succeeds. Wrap this procedure in a new function called t_bind_ephemeral_port(). The selected port will be returned into @addr->sin_port, the caller can use it later to connect() or whatever they need. Link: https://lore.kernel.org/r/918facd1-78ba-2de7-693a-5f8c65ea2fcd@gnuweeb.org Cc: Dylan Yudaken Cc: Facebook Kernel Team Cc: Pavel Begunkov Reviewed-by: Alviro Iskandar Setiawan Tested-by: Alviro Iskandar Setiawan Signed-off-by: Ammar Faizi --- test/helpers.c | 18 ++++++++++++++++++ test/helpers.h | 7 +++++++ 2 files changed, 25 insertions(+) diff --git a/test/helpers.c b/test/helpers.c index 0146533..4d5c402 100644 --- a/test/helpers.c +++ b/test/helpers.c @@ -24,14 +24,32 @@ void *t_malloc(size_t size) { void *ret; ret = malloc(size); assert(ret); return ret; } +/* + * Helper for binding socket to an ephemeral port. + * The port number to be bound is returned in @addr->sin_port. + */ +int t_bind_ephemeral_port(int fd, struct sockaddr_in *addr) +{ + socklen_t addrlen; + + addr->sin_port = 0; + if (bind(fd, (struct sockaddr *)addr, sizeof(*addr))) + return -errno; + + addrlen = sizeof(*addr); + assert(!getsockname(fd, (struct sockaddr *)addr, &addrlen)); + assert(addr->sin_port != 0); + return 0; +} + /* * Helper for allocating size bytes aligned on a boundary. */ void t_posix_memalign(void **memptr, size_t alignment, size_t size) { int ret; ret = posix_memalign(memptr, alignment, size); diff --git a/test/helpers.h b/test/helpers.h index 6d5726c..9ad9947 100644 --- a/test/helpers.h +++ b/test/helpers.h @@ -18,14 +18,21 @@ enum t_setup_ret { enum t_test_result { T_EXIT_PASS = 0, T_EXIT_FAIL = 1, T_EXIT_SKIP = 77, }; +/* + * Helper for binding socket to an ephemeral port. + * The port number to be bound is returned in @addr->sin_port. + */ +int t_bind_ephemeral_port(int fd, struct sockaddr_in *addr); + + /* * Helper for allocating memory in tests. */ void *t_malloc(size_t size); /* -- Ammar Faizi