packet_out.c

linux 下的aodv实现源代码

/*
               Kernel AODV  v2.1
National Institute of Standards and Technology
               Luke Klein-Berndt
-----------------------------------------------------
  Version 2.1 new features:
     * Much more stable!
     * Added locks around important areas
     * Multihop Internet gatewaying now works
     * Multicast hack added
     * 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 struct route_table_entry *g_my_entry;
extern u_int32_t        g_my_ip;
extern u_int32_t  g_broadcast_ip;
extern struct nf_hook_ops output_filter;

#ifdef AODV_MULTICAST
static u_int16_t temp_id=0;
#endif

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

   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 AODV_MULTICAST    
    if(hooknum==NF_IP_LOCAL_OUT)
      {
	if ( (multicast_test(ip->daddr)) && (ip->id==0) && (ip->ttl!=0))
	  {
	    temp_id++;
	    ip->id=htons(temp_id);
	    ip->check = 0;


	    ip->check = ip_fast_csum((unsigned char *) ip, ip->ihl);
	  }
      }
#endif
    

#ifdef AODV_MULTICAST
    if (multicast_test(ip->daddr) || (ip->daddr==g_broadcast_ip) )
#else
    if  (ip->daddr==g_broadcast_ip)
#endif
      {
	monitor.bytes=(*skb)->len + monitor.bytes;
	monitor.packets++;
        return NF_ACCEPT;
      }
    
    //Try to get a route to the destination
    tmp_route=find_route_table_entry(ip->daddr);    

    
#ifdef AODV_GATEWAY
    if (adhoc_subnet_test(ip->daddr) &&( (tmp_route==NULL) || !(tmp_route->route_valid)))
#else
      if ( (tmp_route==NULL) || !(tmp_route->route_valid))
#endif
       {
	 printk("Generating a RREQ for: %s\n",inet_ntoa(ip->daddr));
	 gen_rreq(g_my_ip,ip->daddr);
	 return NF_QUEUE;
       }

if ((tmp_route!=NULL) && (tmp_route->route_valid))  //Found after an LONG search by Jon Anderson
     tmp_route->lifetime = MAX(tmp_route->lifetime,getcurrtime() + ACTIVE_ROUTE_TIMEOUT);
     
     monitor.bytes=(*skb)->len + monitor.bytes;
     monitor.packets++;
     return NF_ACCEPT;
}