/* Find out whether any buffered packet can benefit from the
* reverse route.
* May need some change in the following code - Mahesh 09/11/99
*/
/*如果有到反向路径的分组报文，则发送*/
assert (rt0->rt_flags == RTF_UP);
Packet *buffered_pkt;
while ((buffered_pkt = rqueue.deque(rt0->rt_dst))) {
if (rt0 && (rt0->rt_flags == RTF_UP)) {
assert(rt0->rt_hops != INFINITY2);
forward(rt0, buffered_pkt, NO_DELAY);
}
}
}
// End for putting reverse route in rt table
/*
* We have taken care of the reverse route stuff.
* Now see whether we can send a route reply.
*/
//寻找到目的节点的路由
rt = rtable.rt_lookup(rq->rq_dst);
// First check if I am the destination ..
/*如果本节点就是目的节点，直接发送路由应答报文*/
if(rq->rq_dst == index) {
#ifdef DEBUG
fprintf(stderr, "%d - %s: destination sending reply\n",
index, __FUNCTION__);
#endif // DEBUG
// Just to be safe, I use the max. Somebody may have
// incremented the dst seqno.
seqno = max(seqno, rq->rq_dst_seqno)+1;
if (seqno%2) seqno++;
sendReply(rq->rq_src, // IP Destination
1, // Hop Count
index, // Dest IP Address
seqno, // Dest Sequence Num
MY_ROUTE_TIMEOUT, // Lifetime
rq->rq_timestamp); // timestamp
Packet::free(p);
}
// I am not the destination, but I may have a fresh enough route.
/*如果不是目的节点，但是有到目的节点的路径，也发送路由应答报文*/
else if (rt && (rt->rt_hops != INFINITY2) &&
(rt->rt_seqno >= rq->rq_dst_seqno) ) {
//assert (rt->rt_flags == RTF_UP);
assert(rq->rq_dst == rt->rt_dst);
//assert ((rt->rt_seqno%2) == 0); // is the seqno even?
sendReply(rq->rq_src,
rt->rt_hops + 1,
rq->rq_dst,
rt->rt_seqno,
(u_int32_t) (rt->rt_expire - CURRENT_TIME),
// rt->rt_expire - CURRENT_TIME,
rq->rq_timestamp);
// Insert nexthops to RREQ source and RREQ destination in the
// precursor lists of destination and source respectively
rt->pc_insert(rt0->rt_nexthop); // 加入前缀列表
rt0->pc_insert(rt->rt_nexthop); // 加入前缀列表
#ifdef RREQ_GRAT_RREP
sendReply(rq->rq_dst,
rq->rq_hop_count,
rq->rq_src,
rq->rq_src_seqno,
(u_int32_t) (rt->rt_expire - CURRENT_TIME),
// rt->rt_expire - CURRENT_TIME,
rq->rq_timestamp);
#endif
// TODO: send grat RREP to dst if G flag set in RREQ using rq->rq_src_seqno, rq->rq_hop_counT
// DONE: Included gratuitous replies to be sent as per IETF aodv draft specification. As of now, G flag has not been dynamically used and is always set or reset in aodv-packet.h --- Anant Utgikar, 09/16/02.
Packet::free(p);
}
/*
* Can't reply. So forward the Route Request
*/
//不能应答此报文，则继续广播
else {
ih->saddr() = index;
ih->daddr() = IP_BROADCAST;
rq->rq_hop_count += 1;
// Maximum sequence number seen en route
if (rt) rq->rq_dst_seqno = max(rt->rt_seqno, rq->rq_dst_seqno);
forward((aodv_rt_entry*) 0, p, DELAY);
}
}