Hello everybody,

First of all, sorry for my English
I have changed the ip_forward function in order to add a timer : when a packet comes, it will be delayed about 1 or 2 seconds. Then, it will be forwarded.
But if an other packet comes when a previous packet is waiting, there will be a problem. So I want to use threads to avoid blocking states.

But I obtained lots of errors and warnings.
Code:
#include <linux/types.h>
#include <linux/mm.h>
#include <linux/skbuff.h>
#include <linux/ip.h>
#include <linux/icmp.h>
#include <linux/netdevice.h>
#include <linux/slab.h>
#include <net/sock.h>
#include <net/ip.h>
#include <net/tcp.h>
#include <net/udp.h>
#include <net/icmp.h>
#include <linux/tcp.h>
#include <linux/udp.h>
#include <linux/netfilter_ipv4.h>
#include <net/checksum.h>
#include <linux/route.h>
#include <net/route.h>
#include <net/xfrm.h>
#include <linux/init.h>
#include <linux/linkage.h>
#include <linux/unistd.h>
#include <linux/delay.h>
#include <linux/kernel.h>
#include <linux/sysctl.h>
#include <linux/compiler.h>
#include <linux/module.h>
#include <linux/jiffies.h>
#include <linux/list.h>
#include <linux/jhash.h>
#include <linux/random.h>
#include <net/dst.h>
#include <net/inetpeer.h>
#include <net/inet_frag.h>
#include <linux/inet.h>
#include <linux/netfilter_ipv4.h>
#include <linux/kthread.h>
#include <linux/delay.h>
#include <linux/time.h>

int ip_forward(struct sk_buff *skb)
{
        struct iphdr *iph;        /* Our header */
        struct rtable *rt;        /* Route we use */
        struct ip_options * opt        = &(IPCB(skb)->opt);
	struct task_struct *threadIpForward;

        if (skb_warn_if_lro(skb))
                goto drop;

        if (!xfrm4_policy_check(NULL, XFRM_POLICY_FWD, skb))
                goto drop;

        if (IPCB(skb)->opt.router_alert && ip_call_ra_chain(skb))
                return NET_RX_SUCCESS;

        if (skb->pkt_type != PACKET_HOST)
                goto drop;

        skb_forward_csum(skb);

        /*
         *        According to the RFC, we must first decrease the TTL field. If
         *        that reaches zero, we must reply an ICMP control message telling
         *        that the packet's lifetime expired.
         */
        if (ip_hdr(skb)->ttl <= 1)
                goto too_many_hops;

        if (!xfrm4_route_forward(skb))
                goto drop;

        rt = skb_rtable(skb);

        if (opt->is_strictroute && rt->rt_dst != rt->rt_gateway)
                goto sr_failed;

        if (unlikely(skb->len > dst_mtu(&rt->u.dst) && !skb_is_gso(skb) &&
                     (ip_hdr(skb)->frag_off & htons(IP_DF))) && !skb->local_df) {
                IP_INC_STATS(dev_net(rt->u.dst.dev), IPSTATS_MIB_FRAGFAILS);
                icmp_send(skb, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED,
                          htonl(dst_mtu(&rt->u.dst)));
                goto drop;
        }

        /* We are about to mangle packet. Copy it! */
        if (skb_cow(skb, LL_RESERVED_SPACE(rt->u.dst.dev)+rt->u.dst.header_len))
                goto drop;
        iph = ip_hdr(skb);

        /* Decrease ttl after skb cow done */
        ip_decrease_ttl(iph);

        /*
         *        We now generate an ICMP HOST REDIRECT giving the route
         *        we calculated.
         */
        if (rt->rt_flags&RTCF_DOREDIRECT && !opt->srr && !skb_sec_path(skb))
                ip_rt_send_redirect(skb);
	skb->priority = rt_tos2priority(iph->tos);
		
 	threadIpForward = kthread_run(ip_forward_thread,(skb,5),"IP_FORWARD_THREAD"); 
	return 0;


sr_failed:
        /*
         *        Strict routing permits no gatewaying
         */
         icmp_send(skb, ICMP_DEST_UNREACH, ICMP_SR_FAILED, 0);
         goto drop;

too_many_hops:
        /* Tell the sender its packet died... */
        IP_INC_STATS_BH(dev_net(skb_dst(skb)->dev), IPSTATS_MIB_INHDRERRORS);
        icmp_send(skb, ICMP_TIME_EXCEEDED, ICMP_EXC_TTL, 0);
drop:
        kfree_skb(skb);
        return NET_RX_DROP;
}

and the ip_forward_thread function is :
Code:
int ip_forward_thread(struct sk_buff *skb, int a)
{
        struct rtable *rt;        /* Route we use */
	delay(1000*a);
        return NF_HOOK(NFPROTO_IPV4, NF_INET_FORWARD, skb, skb->dev,
                       rt->u.dst.dev, ip_forward_finish);
}

net/ipv4/ip_forward.c: In function ‘ip_forward_thread’:
net/ipv4/ip_forward.c:78: error: implicit declaration of function ‘delay’
net/ipv4/ip_forward.c: In function ‘ip_forward’:
net/ipv4/ip_forward.c:144: warning: left-hand operand of comma expression has no effect
net/ipv4/ip_forward.c:144: warning: passing argument 1 of ‘kthread_create’ from incompatible pointer type
include/linux/kthread.h:7: note: expected ‘int (*)(void *)’ but argument is of type ‘int (*)(struct sk_buff *, int)’
net/ipv4/ip_forward.c:144: warning: passing argument 2 of ‘kthread_create’ makes pointer from integer without a cast
include/linux/kthread.h:7: note: expected ‘void *’ but argument is of type ‘int’


Please help me

Thank you for your help