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netfilter: nf_nat: add nf_nat_csum()

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Add a static function nf_nat_csum() to replace the duplicate code in
nf_nat_mangle_udp_packet() and __nf_nat_mangle_tcp_packet().

Signed-off-by: Changli Gao <xiaosuo@gmail.com>
Signed-off-by: Patrick McHardy <kaber@trash.net>
This commit is contained in:
Changli Gao 2010-09-15 19:24:50 +02:00 committed by Patrick McHardy
parent 068e8a3032
commit 0abee5260b
1 changed files with 31 additions and 45 deletions
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76
net/ipv4/netfilter/nf_nat_helper.c
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@ -153,6 +153,35 @@ void nf_nat_set_seq_adjust(struct nf_conn *ct, enum ip_conntrack_info ctinfo,
}
EXPORT_SYMBOL_GPL(nf_nat_set_seq_adjust);
static void nf_nat_csum(struct sk_buff *skb, struct iphdr *iph, void *data,
int datalen, __sum16 *check, int oldlen)
{
struct rtable *rt = skb_rtable(skb);
if (skb->ip_summed != CHECKSUM_PARTIAL) {
if (!(rt->rt_flags & RTCF_LOCAL) &&
skb->dev->features & NETIF_F_V4_CSUM) {
skb->ip_summed = CHECKSUM_PARTIAL;
skb->csum_start = skb_headroom(skb) +
skb_network_offset(skb) +
iph->ihl * 4;
skb->csum_offset = (void *)check - data;
*check = ~csum_tcpudp_magic(iph->saddr, iph->daddr,
datalen, iph->protocol, 0);
} else {
*check = 0;
*check = csum_tcpudp_magic(iph->saddr, iph->daddr,
datalen, iph->protocol,
csum_partial(data, datalen,
0));
if (iph->protocol == IPPROTO_UDP && !*check)
*check = CSUM_MANGLED_0;
}
} else
inet_proto_csum_replace2(check, skb,
htons(oldlen), htons(datalen), 1);
}
/* Generic function for mangling variable-length address changes inside
* NATed TCP connections (like the PORT XXX,XXX,XXX,XXX,XXX,XXX
* command in FTP).
@ -169,7 +198,6 @@ int __nf_nat_mangle_tcp_packet(struct sk_buff *skb,
const char *rep_buffer,
unsigned int rep_len, bool adjust)
{
struct rtable *rt = skb_rtable(skb);
struct iphdr *iph;
struct tcphdr *tcph;
int oldlen, datalen;
@ -192,26 +220,7 @@ int __nf_nat_mangle_tcp_packet(struct sk_buff *skb,
match_offset, match_len, rep_buffer, rep_len);
datalen = skb->len - iph->ihl*4;
if (skb->ip_summed != CHECKSUM_PARTIAL) {
if (!(rt->rt_flags & RTCF_LOCAL) &&
skb->dev->features & NETIF_F_V4_CSUM) {
skb->ip_summed = CHECKSUM_PARTIAL;
skb->csum_start = skb_headroom(skb) +
skb_network_offset(skb) +
iph->ihl * 4;
skb->csum_offset = offsetof(struct tcphdr, check);
tcph->check = ~tcp_v4_check(datalen,
iph->saddr, iph->daddr, 0);
} else {
tcph->check = 0;
tcph->check = tcp_v4_check(datalen,
iph->saddr, iph->daddr,
csum_partial(tcph,
datalen, 0));
}
} else
inet_proto_csum_replace2(&tcph->check, skb,
htons(oldlen), htons(datalen), 1);
nf_nat_csum(skb, iph, tcph, datalen, &tcph->check, oldlen);
if (adjust && rep_len != match_len)
nf_nat_set_seq_adjust(ct, ctinfo, tcph->seq,
@ -240,7 +249,6 @@ nf_nat_mangle_udp_packet(struct sk_buff *skb,
const char *rep_buffer,
unsigned int rep_len)
{
struct rtable *rt = skb_rtable(skb);
struct iphdr *iph;
struct udphdr *udph;
int datalen, oldlen;
@ -274,29 +282,7 @@ nf_nat_mangle_udp_packet(struct sk_buff *skb,
if (!udph->check && skb->ip_summed != CHECKSUM_PARTIAL)
return 1;
if (skb->ip_summed != CHECKSUM_PARTIAL) {
if (!(rt->rt_flags & RTCF_LOCAL) &&
skb->dev->features & NETIF_F_V4_CSUM) {
skb->ip_summed = CHECKSUM_PARTIAL;
skb->csum_start = skb_headroom(skb) +
skb_network_offset(skb) +
iph->ihl * 4;
skb->csum_offset = offsetof(struct udphdr, check);
udph->check = ~csum_tcpudp_magic(iph->saddr, iph->daddr,
datalen, IPPROTO_UDP,
0);
} else {
udph->check = 0;
udph->check = csum_tcpudp_magic(iph->saddr, iph->daddr,
datalen, IPPROTO_UDP,
csum_partial(udph,
datalen, 0));
if (!udph->check)
udph->check = CSUM_MANGLED_0;
}
} else
inet_proto_csum_replace2(&udph->check, skb,
htons(oldlen), htons(datalen), 1);
nf_nat_csum(skb, iph, udph, datalen, &udph->check, oldlen);
return 1;
}