void
AODV::sendRequest(nsaddr_t dst) {
// Allocate a RREQ packet
Packet *p = Packet::alloc();
struct hdr_cmn *ch = HDR_CMN(p);
struct hdr_ip *ih = HDR_IP(p);
struct hdr_aodv_request *rq = HDR_AODV_REQUEST(p);
aodv_rt_entry *rt = rtable.rt_lookup(dst);
assert(rt);
/*
* Rate limit sending of Route Requests. We are very conservative
* about sending out route requests.
*/
//如果有到目的节点的路由，则终止请求
if (rt->rt_flags == RTF_UP) {
assert(rt->rt_hops != INFINITY2);
Packet::free((Packet *)p);
return;
}
//如果请求时间还有到，则不发送
if (rt->rt_req_timeout > CURRENT_TIME) {
Packet::free((Packet *)p);
return;
}
// rt_req_cnt is the no. of times we did network-wide broadcast
// RREQ_RETRIES is the maximum number we will allow before
// going to a long timeout.
//如果请求次数大于最大的发送请求次数，则丢掉分组，不发送请求
if (rt->rt_req_cnt > RREQ_RETRIES) {
rt->rt_req_timeout = CURRENT_TIME + MAX_RREQ_TIMEOUT;
rt->rt_req_cnt = 0;
Packet *buf_pkt;
while ((buf_pkt = rqueue.deque(rt->rt_dst))) {
drop(buf_pkt, DROP_RTR_NO_ROUTE);
}
Packet::free((Packet *)p);
return;
}
#ifdef DEBUG
fprintf(stderr, "(%2d) - %2d sending Route Request, dst: %d\n",
++route_request, index, rt->rt_dst);
#endif // DEBUG
// Determine the TTL to be used this time.
// Dynamic TTL evaluation - SRD
rt->rt_req_last_ttl = max(rt->rt_req_last_ttl,rt->rt_last_hop_count);
//路由请求的环搜索
//第一次广播请求��选择初始跳数；随后逐渐扩大
if (0 == rt->rt_req_last_ttl) {
// first time query broadcast
ih->ttl_ = TTL_START;
}
else {
// Expanding ring search.
if (rt->rt_req_last_ttl < TTL_THRESHOLD)
ih->ttl_ = rt->rt_req_last_ttl + TTL_INCREMENT;
else {
// network-wide broadcast
ih->ttl_ = NETWORK_DIAMETER;
rt->rt_req_cnt += 1;
}
}
// remember the TTL used for the next time
rt->rt_req_last_ttl = ih->ttl_;//为下次使用做记录
// PerHopTime is the roundtrip time per hop for route requests.
// The factor 2.0 is just to be safe .. SRD 5/22/99
// Also note that we are making timeouts to be larger if we have
// done network wide broadcast before.
rt->rt_req_timeout = 2.0 * (double) ih->ttl_ * PerHopTime(rt);
if (rt->rt_req_cnt > 0)
rt->rt_req_timeout *= rt->rt_req_cnt;
rt->rt_req_timeout += CURRENT_TIME;
// Don't let the timeout to be too large, however .. SRD 6/8/99
if (rt->rt_req_timeout > CURRENT_TIME + MAX_RREQ_TIMEOUT)
rt->rt_req_timeout = CURRENT_TIME + MAX_RREQ_TIMEOUT;
rt->rt_expire = 0;
#ifdef DEBUG
fprintf(stderr, "(%2d) - %2d sending Route Request, dst: %d, tout %f ms\n",
++route_request,
index, rt->rt_dst,
rt->rt_req_timeout - CURRENT_TIME);
#endif // DEBUG
// Fill out the RREQ packet
// ch->uid() = 0;
ch->ptype() = PT_AODV;
ch->size() = IP_HDR_LEN + rq->size();
ch->iface() = -2;
ch->error() = 0;
ch->addr_type() = NS_AF_NONE;
ch->prev_hop_ = index; // AODV hack
ih->saddr() = index;
ih->daddr() = IP_BROADCAST;
ih->sport() = RT_PORT;
ih->dport() = RT_PORT;
// Fill up some more fields.
rq->rq_type = AODVTYPE_RREQ;
rq->rq_hop_count = 1;
rq->rq_bcast_id = bid++;
rq->rq_dst = dst;
rq->rq_dst_seqno = (rt ? rt->rt_seqno : 0);
rq->rq_src = index;
seqno += 2;
assert ((seqno%2) == 0);
rq->rq_src_seqno = seqno;
rq->rq_timestamp = CURRENT_TIME;
Scheduler::instance().schedule(target_, p, 0.);
}
void
AODV::sendReply(nsaddr_t ipdst, u_int32_t hop_count, nsaddr_t rpdst,
u_int32_t rpseq, u_int32_t lifetime, double timestamp) {
Packet *p = Packet::alloc();
struct hdr_cmn *ch = HDR_CMN(p);
struct hdr_ip *ih = HDR_IP(p);
struct hdr_aodv_reply *rp = HDR_AODV_REPLY(p);
aodv_rt_entry *rt = rtable.rt_lookup(ipdst);
#ifdef DEBUG
fprintf(stderr, "sending Reply from %d at %.2f\n", index, Scheduler::instance().clock());
#endif // DEBUG
assert(rt);