NS技巧8

shuying3344

一．怎么样广播数据
根据AODV中recv（）函数的代码,我们可以知道，只需要将IP包头的目的地址设为广播地址即可，ih->daddr() != IP_BROADCAST
void
AODV::recv(Packet *p, Handler*) {
//访问通用以及IP包头
struct hdr_cmn *ch = HDR_CMN(p);
struct hdr_ip *ih = HDR_IP(p);

assert(initialized());
//assert(p->incoming == 0);
// XXXXX NOTE: use of incoming flag has been depracated; In order to track direction of pkt flow, direction_ in hdr_cmn is used instead. see packet.h for details.

if(ch->ptype() == PT_AODV) {
   ih->ttl_ -= 1;
   recvAODV(p);
   return;
}


/*
  *  Must be a packet I'm originating...
  */
if((ih->saddr() == index) && (ch->num_forwards() == 0)) {
/*
  * Add the IP Header
  */
   ch->size() += IP_HDR_LEN;
   // Added by Parag Dadhania && John Novatnack to handle broadcasting
   if ( (u_int32_t)ih->daddr() != IP_BROADCAST)
     ih->ttl_ = NETWORK_DIAMETER;
}
/*
  *  I received a packet that I sent.  Probably
  *  a routing loop.
  */
else if(ih->saddr() == index) {
   drop(p, DROP_RTR_ROUTE_LOOP);
   return;
}
/*
  *  Packet I'm forwarding...
  */
else {
/*
  *  Check the TTL.  If it is zero, then discard.
  */
   if(--ih->ttl_ == 0) {
     drop(p, DROP_RTR_TTL);
     return;
   }
}
// Added by Parag Dadhania && John Novatnack to handle broadcasting
if ( (u_int32_t)ih->daddr() != IP_BROADCAST)
   rt_resolve(p);
else
   forward((aodv_rt_entry*) 0, p, NO_DELAY);
}


本文来自ChinaUnix博客，如果查看原文请点：http://blog.chinaunix.net/u1/47073/showart_1359568.html