packet_out.c

无线网络路有协议aodv的 linux的实现

/***************************************************************************
                          packet_out.c  -  description
                             -------------------
    begin                : Mon Aug 4 2003
    copyright            : (C) 2003 by Luke Klein-Berndt
    email                : [e-mail]
 ***************************************************************************/

#include "packet_out.h"

extern u_int32_t g_broadcast_ip;
extern u_int32_t g_my_ip;
extern u_int8_t g_aodv_gateway;


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= (*skb)->nh.iph;
    struct net_device *dev= (*skb)->dev;
    aodv_route *tmp_route;
		aodv_neigh *tmp_neigh;
    void *p = (uint32_t *) ip + ip->ihl;
    struct udphdr *udp = p; //(struct udphdr *) ip + ip->ihl;
    struct ethhdr *mac = (*skb)->mac.ethernet;  //Thanks to Randy Pitz for adding this extra check...

	
    if (ip->daddr == g_broadcast_ip)
    {
        return NF_ACCEPT;
    }



    //Need this additional check, otherwise users on the
    //gateway will not be able to access the externel 
    //network. Remote user located outside the aodv_subnet
    //also require this check if they are access services on
    //the gateway node. 28 April 2004 pb 
    if(g_aodv_gateway && !aodv_subnet_test(ip->daddr))
    {
        return NF_ACCEPT;
    }
	
    //Try to get a route to the destination
    tmp_route = find_aodv_route(ip->daddr);
    if ((tmp_route == NULL) || !(tmp_route->route_valid))
    {
        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
    {
				if (!tmp_route->self_route)
        tmp_route->lifetime =  getcurrtime() + ACTIVE_ROUTE_TIMEOUT;
    }
    
    return NF_ACCEPT;
}