/*
* Send all packets queued in the sendbuffer destined for
* this destination.
* XXX - observe the "second" use of p.
*/
/*如果有到反向路径的数据包，则发送*/
Packet *buf_pkt;
while((buf_pkt = rqueue.deque(rt->rt_dst))) {
if(rt->rt_hops != INFINITY2) {
assert (rt->rt_flags == RTF_UP);
// Delay them a little to help ARP. Otherwise ARP
// may drop packets. -SRD 5/23/99
forward(rt, buf_pkt, delay);
delay += ARP_DELAY;
}
}
}
else {
suppress_reply = 1;//序列号过小且没有更小的跳数
}

/*
* If reply is for me, discard it.
*/

if(ih->daddr() == index || suppress_reply)
{//如果此节点是源节点或者应答报文不够新且没有更小的跳数
Packet::free(p);
}
/*
* Otherwise, forward the Route Reply.
*/
else {
// Find the rt entry
aodv_rt_entry *rt0 = rtable.rt_lookup(ih->daddr());
// If the rt is up, forward
if(rt0 && (rt0->rt_hops != INFINITY2))
{
//如果存在到源节点的路径，则转发应答报文，否则丢弃应答报文
assert (rt0->rt_flags == RTF_UP);
rp->rp_hop_count += 1;
rp->rp_src = index;
forward(rt0, p, NO_DELAY);
// Insert the nexthop towards the RREQ source to
// the precursor list of the RREQ destination
rt->pc_insert(rt0->rt_nexthop); // nexthop to RREQ source

}
else {//
// I don't know how to forward .. drop the reply.
#ifdef DEBUG
fprintf(stderr, "%s: dropping Route Reply\n", __FUNCTION__);
#endif // DEBUG
drop(p, DROP_RTR_NO_ROUTE);
}
}
}

/*从邻居那里收到错误分组，检查自己路由表是否有通过此邻居到达目的地的
路由条目，如果有，则将此路由删除，并继续向邻居广播错误分组*/
void
AODV::recvError(Packet *p) {
struct hdr_ip *ih = HDR_IP(p);
struct hdr_aodv_error *re = HDR_AODV_ERROR(p);
aodv_rt_entry *rt;
u_int8_t i;
Packet *rerr = Packet::alloc();
struct hdr_aodv_error *nre = HDR_AODV_ERROR(rerr);

nre->DestCount = 0;
/*遍历错误分组中每一个不可达路由*/
for (i=0; iDestCount; i++) {
// For each unreachable destination
rt = rtable.rt_lookup(re->unreachable_dst[i]);
/*是否存在经过发送错误分组的邻居的路由*/
if ( rt && (rt->rt_hops != INFINITY2) &&
(rt->rt_nexthop == ih->saddr()) &&
(rt->rt_seqno <= re->unreachable_dst_seqno[i]) ) {
assert(rt->rt_flags == RTF_UP);
assert((rt->rt_seqno%2) == 0); // 奇数代表无穷大，无效的意思
#ifdef DEBUG
fprintf(stderr, "%s(%f): %d\t(%d\t%u\t%d)\t(%d\t%u\t%d)\n", __FUNCTION__,CURRENT_TIME,
index, rt->rt_dst, rt->rt_seqno, rt->rt_nexthop,
re->unreachable_dst[i],re->unreachable_dst_seqno[i],
ih->saddr());
#endif // DEBUG
rt->rt_seqno = re->unreachable_dst_seqno[i];
rt_down(rt);//将此路由down掉

// Not sure whether this is the right thing to do
/*查看队列中是否有下一跳是此邻居的分组
若有的话，直接丢包；具体请看queue/priqueue.cc的filter函数*/
Packet *pkt;
while((pkt = ifqueue->filter(ih->saddr()))) {
drop(pkt, DROP_RTR_MAC_CALLBACK);
}

// if precursor list non-empty add to RERR and delete the precursor list
/*如果此路由的前缀列表非空，将此节点不可达的目的地记录在新的路由分组中
并且删除此路由的前缀列表*/
if (!rt->pc_empty()) {
nre->unreachable_dst[nre->DestCount] = rt->rt_dst;
nre->unreachable_dst_seqno[nre->DestCount] = rt->rt_seqno;
nre->DestCount += 1;
rt->pc_delete();
}
}
}
/*如果此节点有不可达路由，则继续广播错误分组*/
if (nre->DestCount > 0) {
#ifdef DEBUG
fprintf(stderr, "%s(%f): %d\t sending RERR...\n", __FUNCTION__, CURRENT_TIME, index);
#endif // DEBUG
sendError(rerr);
}
else {
Packet::free(rerr);
}

Packet::free(p);
}

/*
Packet Transmission Routines
*/