From patchwork Fri Apr 26 08:33:29 2013 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Florian Westphal X-Patchwork-Id: 239755 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id 195792C0106 for ; Fri, 26 Apr 2013 18:31:32 +1000 (EST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754627Ab3DZIb3 (ORCPT ); Fri, 26 Apr 2013 04:31:29 -0400 Received: from Chamillionaire.breakpoint.cc ([80.244.247.6]:48574 "EHLO Chamillionaire.breakpoint.cc" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932477Ab3DZIb0 (ORCPT ); Fri, 26 Apr 2013 04:31:26 -0400 Received: from fw by Chamillionaire.breakpoint.cc with local (Exim 4.72) (envelope-from ) id 1UVe3x-0005qS-FA; Fri, 26 Apr 2013 10:31:25 +0200 From: Florian Westphal To: netfilter-devel@vger.kernel.org Cc: Florian Westphal Subject: [PATCH 2/4] examples/nf-queue: handle recv error, use larger buffer Date: Fri, 26 Apr 2013 10:33:29 +0200 Message-Id: <1366965211-23412-3-git-send-email-fw@strlen.de> X-Mailer: git-send-email 1.7.8.6 In-Reply-To: <1366965211-23412-1-git-send-email-fw@strlen.de> References: <1366965211-23412-1-git-send-email-fw@strlen.de> Sender: netfilter-devel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netfilter-devel@vger.kernel.org We ask for 0xffff copy size, so we need a buffer that can hold 0xffff, plus a few more bytes to allow for netlink attributes. Also, turn off ENOBUFS. Signed-off-by: Florian Westphal --- examples/nf-queue.c | 37 ++++++++++++++++++++++++------------- 1 files changed, 24 insertions(+), 13 deletions(-) diff --git a/examples/nf-queue.c b/examples/nf-queue.c index 7adac21..6641a24 100644 --- a/examples/nf-queue.c +++ b/examples/nf-queue.c @@ -1,3 +1,4 @@ +#include #include #include #include @@ -82,7 +83,9 @@ static int queue_cb(const struct nlmsghdr *nlh, void *data) int main(int argc, char *argv[]) { - char buf[MNL_SOCKET_BUFFER_SIZE]; + char *buf; + /* largest possible packet payload, plus netlink data overhead: */ + size_t sizeof_buf = 0xffff + (MNL_SOCKET_BUFFER_SIZE/2); struct nlmsghdr *nlh; int ret; unsigned int portid, queue_num; @@ -105,6 +108,12 @@ int main(int argc, char *argv[]) } portid = mnl_socket_get_portid(nl); + buf = malloc(sizeof_buf); + if (!buf) { + perror("allocate receive buffer"); + exit(EXIT_FAILURE); + } + nlh = nfq_hdr_put(buf, NFQNL_MSG_CONFIG, 0); nfq_nlmsg_cfg_put_cmd(nlh, AF_INET, NFQNL_CFG_CMD_PF_UNBIND); @@ -137,23 +146,25 @@ int main(int argc, char *argv[]) exit(EXIT_FAILURE); } - ret = mnl_socket_recvfrom(nl, buf, sizeof(buf)); - if (ret == -1) { - perror("mnl_socket_recvfrom"); - exit(EXIT_FAILURE); - } - while (ret > 0) { - ret = mnl_cb_run(buf, ret, 0, portid, queue_cb, NULL); - if (ret < 0){ - perror("mnl_cb_run"); - exit(EXIT_FAILURE); - } + /* ENOBUFS is signalled to userspace when packets were lost + * on kernel side. In most cases, userspace isn't interested + * in this information, so turn it off. + */ + ret = 1; + mnl_socket_setsockopt(nl, NETLINK_NO_ENOBUFS, &ret, sizeof(int)); - ret = mnl_socket_recvfrom(nl, buf, sizeof(buf)); + for (;;) { + ret = mnl_socket_recvfrom(nl, buf, sizeof_buf); if (ret == -1) { perror("mnl_socket_recvfrom"); exit(EXIT_FAILURE); } + + ret = mnl_cb_run(buf, ret, 0, portid, queue_cb, NULL); + if (ret < 0){ + perror("mnl_cb_run"); + exit(EXIT_FAILURE); + } } mnl_socket_close(nl);