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netfilter: ipt_REJECT: postpone the checksum calculation.

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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 <xiaosuo@gmail.com>
Signed-off-by: Patrick McHardy <kaber@trash.net>
This commit is contained in:
Changli Gao 2010-07-05 10:39:17 +02:00 committed by Patrick McHardy
parent ea8fbe8f19
commit 98b0e84aaa
1 changed files with 5 additions and 5 deletions
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10
net/ipv4/netfilter/ipt_REJECT.c
View file

@ -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)))