packet_out.c

一种AODV实现方法

/*
               Kernel AODV  v2.0
National Institute of Standards and Technology
               Luke Klein-Berndt
-----------------------------------------------------
  Version 2.0 new features:
     * Updated to AODV draft version 11
     * Managed internet gatewaying
     * Monitor wireles signal strength
     * Many bug fixes!
-----------------------------------------------------

Originally based upon MadHoc code. I am not
sure how much of it is left anymore, but MadHoc
proved to be a great starting point.

MadHoc was written by - Fredrik Lilieblad,
Oskar Mattsson, Petra Nylund, Dan Ouchterlony
and Anders Roxenhag Mail: [e-mail]

This software is Open Source under the GNU General Public Licence.

*/

#include "packet_out.h"
/****************************************************

   packet_out
----------------------------------------------------
All packets going out of the computer get
intercepted by netfilter and passed to this
function.
****************************************************/


extern u_int32_t        g_my_ip;
extern u_int32_t  g_broadcast_ip;
extern struct nf_hook_ops output_filter;



/****************************************************

   output_handler
----------------------------------------------------
Looks at all the packets leaving the computer
****************************************************/


unsigned int output_handler(    unsigned int hooknum,struct sk_buff **skb,const struct net_device *in, const struct net_device *out, int (*okfn)(struct sk_buff *))
{
    struct iphdr *ip;
    struct route_table_entry  *tmp_route;
    struct net_device *dev;

    // get some useful pointers
    ip  = (*skb)->nh.iph;
    dev = (*skb)->dev;

#ifdef TRACE
    printk("PACKET_OUT: entered\n");
#endif



    if (ip->daddr==g_broadcast_ip)
    {
#ifdef TRACE
        printk("PACKET_OUT: Broadcast Packet - exit\n");
#endif
        return NF_ACCEPT;
    }

    if (adhoc_subnet_test(ip->daddr))
    {

        //Try to get a route to the destination
        tmp_route=find_route_table_entry(ip->daddr);

        //If the there is no route or it is marked for deletion
        if ((tmp_route==NULL) || !(tmp_route->route_valid))
        {
            //if it is a broadcast message

            //it is a unknown route time to find a new one
#ifdef MESSAGES
            printk("PACKET_OUT: Couldn't find a route to: %s, sending out a RREQ!\n",inet_ntoa(ip->daddr));
#endif


            gen_rreq(g_my_ip,ip->daddr);

#ifdef TRACE
            printk("PACKET_OUT: Tried to find route exited\n");
#endif
            return NF_QUEUE;

        }
        else
        {
            tmp_route->lifetime = MAX(tmp_route->lifetime,getcurrtime() + ACTIVE_ROUTE_TIMEOUT);

        #ifdef TRACE
            printk("PACKET_OUT: Have route updated timer -exited \n");
        #endif

            return NF_ACCEPT;
        }
    }
    else
        return NF_ACCEPT;


}