From mboxrd@z Thu Jan 1 00:00:00 1970 From: kaber@trash.net Subject: [PATCH 02/28] netfilter: ipt_REJECT: postpone the checksum calculation. Date: Mon, 2 Aug 2010 21:57:19 +0200 Message-ID: <1280779065-9333-3-git-send-email-kaber@trash.net> References: <1280779065-9333-1-git-send-email-kaber@trash.net> Cc: netfilter-devel@vger.kernel.org, netdev@vger.kernel.org To: davem@davemloft.net Return-path: In-Reply-To: <1280779065-9333-1-git-send-email-kaber@trash.net> Sender: netdev-owner@vger.kernel.org List-Id: netfilter-devel.vger.kernel.org From: Changli Gao postpone the checksum calculation, then if the output NIC supports checksum offloading, we can utlize it. And though the output NIC doesn't support checksum offloading, but we'll mangle this packet, this can free us from updating the checksum, as the checksum calculation occurs later. Signed-off-by: Changli Gao Signed-off-by: Patrick McHardy --- net/ipv4/netfilter/ipt_REJECT.c | 10 +++++----- 1 files changed, 5 insertions(+), 5 deletions(-) diff --git a/net/ipv4/netfilter/ipt_REJECT.c b/net/ipv4/netfilter/ipt_REJECT.c index f5f4a88..3d0e064 100644 --- a/net/ipv4/netfilter/ipt_REJECT.c +++ b/net/ipv4/netfilter/ipt_REJECT.c @@ -95,10 +95,11 @@ static void send_reset(struct sk_buff *oldskb, int hook) } tcph->rst = 1; - tcph->check = tcp_v4_check(sizeof(struct tcphdr), - niph->saddr, niph->daddr, - csum_partial(tcph, - sizeof(struct tcphdr), 0)); + tcph->check = ~tcp_v4_check(sizeof(struct tcphdr), niph->saddr, + niph->daddr, 0); + nskb->ip_summed = CHECKSUM_PARTIAL; + nskb->csum_start = (unsigned char *)tcph - nskb->head; + nskb->csum_offset = offsetof(struct tcphdr, check); addr_type = RTN_UNSPEC; if (hook != NF_INET_FORWARD @@ -115,7 +116,6 @@ static void send_reset(struct sk_buff *oldskb, int hook) goto free_nskb; niph->ttl = dst_metric(skb_dst(nskb), RTAX_HOPLIMIT); - nskb->ip_summed = CHECKSUM_NONE; /* "Never happens" */ if (nskb->len > dst_mtu(skb_dst(nskb))) -- 1.7.1