From mboxrd@z Thu Jan 1 00:00:00 1970 From: Vikas Subject: Re: Fetching interface name Date: Fri, 25 Sep 2015 16:37:14 +0530 Message-ID: <56052AE2.3040205@oracle.com> References: <5604D75E.8000809@oracle.com> <20150925102252.GA3768@salvia> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: coreteam@netfilter.org, eric@netfilter.org, netfilter-devel@vger.kernel.org To: Pablo Neira Ayuso Return-path: Received: from aserp1040.oracle.com ([141.146.126.69]:18662 "EHLO aserp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754162AbbIYLAz (ORCPT ); Fri, 25 Sep 2015 07:00:55 -0400 In-Reply-To: <20150925102252.GA3768@salvia> Sender: netfilter-devel-owner@vger.kernel.org List-ID: This will indeed help us. Thanx for the pointer. Regards Vikas On 25/09/15 3:52 pm, Pablo Neira Ayuso wrote: > 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