From mboxrd@z Thu Jan 1 00:00:00 1970 From: Pablo Neira Ayuso Subject: Re: Fetching interface name Date: Fri, 25 Sep 2015 12:22:52 +0200 Message-ID: <20150925102252.GA3768@salvia> References: <5604D75E.8000809@oracle.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: coreteam@netfilter.org, eric@netfilter.org, netfilter-devel@vger.kernel.org To: Vikas Return-path: Received: from mail.us.es ([193.147.175.20]:55549 "EHLO mail.us.es" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752178AbbIYKQE (ORCPT ); Fri, 25 Sep 2015 06:16:04 -0400 Content-Disposition: inline In-Reply-To: <5604D75E.8000809@oracle.com> Sender: netfilter-devel-owner@vger.kernel.org List-ID: Cc'ing netfilter-devel for development questions. On Fri, Sep 25, 2015 at 10:40:54AM +0530, Vikas wrote: > Hi, > > In the netlink infra I could see these attributes: > > enum nfqnl_attr_type { > 0034 NFQA_UNSPEC,0035 NFQA_PACKET_HDR, > 0036 NFQA_VERDICT_HDR, /* nfqnl_msg_verdict_hrd */ > 0037 NFQA_MARK, /* __u32 nfmark */ > 0038 NFQA_TIMESTAMP, /* nfqnl_msg_packet_timestamp */ > 0039*NFQA_IFINDEX_INDEV*, /* __u32 ifindex */ > 0040*NFQA_IFINDEX_OUTDEV*, /* __u32 ifindex */ > 0041 NFQA_IFINDEX_PHYSINDEV, /* __u32 ifindex */ > 0042 NFQA_IFINDEX_PHYSOUTDEV, /* __u32 ifindex */ > 0043 NFQA_HWADDR, /* nfqnl_msg_packet_hw */ > 0044 NFQA_PAYLOAD, /* opaque data payload */ > 0045 NFQA_CT, /* nf_conntrack_netlink.h */ > 0046 NFQA_CT_INFO, /* enum ip_conntrack_info */ > 0047 NFQA_CAP_LEN, /* __u32 length of captured packet */ > 0048 NFQA_SKB_INFO, /* __u32 skb meta information */ > 0049 NFQA_EXP, /* nf_conntrack_netlink.h */ > 0050 > 0051 __NFQA_MAX > 0052 }; > > Currently we are doing this to get the input/putput interface index: > input_interface_index = mnl_attr_get_u32(tb[NFQA_IFINDEX_INDEV]); // where tb being a nlattr structure: struct nlattr *tb[NFQA_MAX] > output_interface_index = mnl_attr_get_u32(tb[NFQA_IFINDEX_OUTDEV]); > > Is there a way(or any attribute like NFQA_IFINDEX_INDEV/OUTDEV) by > which we can get the input/output interface*name*? I don't want to > use kernel call: if_indextoname() to map index to name, because it > may be time consuming. It should be easy to build a cache of ifindex in userspace and maintain it up to date. So you don't need to use if_indextoname() since it generates quite a lot of netlink traffic between kernel and userspace. You can probably contribute some example to libmnl that we can apply to the tree. You can use this change I made quite recently as reference for that code: http://git.netfilter.org/nftables/commit/?id=3ed296118a065caff5600e60d4f7ef18e137f9a0