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1、第一部分：RREQ 分组的处理流程图：第二部分 与流程图对应的程序解析部分：voidAODV:recvRequest(Packet *p) struct hdr_ip *ih = HDR_IP(p);struct hdr_aodv_request *rq = HDR_AODV_REQUEST(p);aodv_rt_entry *rt;/*=*/该分组是否由自己产生if(rq-rq_src = index) #ifdef DEBUGfprintf(stderr, %s: got my own REQUESTn, _FUNCTION_);#endif / DEBUG/如果是，回收分组Packet:
2、free(p);return; /如果不是，判断是否已经收到该分组if (id_lookup(rq-rq_src, rq-rq_bcast_id) #ifdef DEBUGfprintf(stderr, %s: discarding requestn, _FUNCTION_);#endif / DEBUG/如果收到过该分组，回收分组Packet:free(p);return;/*=*/如果没收到过该分组/将收到的广播分组存入 Broadcast ID Cache 中/* Cache the broadcast ID*/id_insert(rq-rq_src, rq-rq_bcast_id);
3、aodv_rt_entry *rt0; / rt0 is the reverse route /是否存在反向路由项？rt0 = rtable.rt_lookup(rq-rq_src);/如果不存在反向路由项，新建反向路由if(rt0 = 0) /* if not in the route table / create an entry for the reverse route.rt0 = rtable.rt_add(rq-rq_src); rt0-rt_expire = max(rt0-rt_expire, (CURRENT_TIME + REV_ROUTE_LIFE);/若存在反向路由项/
4、判断反向路由是否需要更新 ？if ( (rq-rq_src_seqno rt0-rt_seqno ) |(rq-rq_src_seqno = rt0-rt_seqno) & (rq-rq_hop_count rt_hops) ) /这里就是路由判据，当遇到新的 RREQ 的时候，比较在路由表中已经存在的到目的节点的路由，比较目的节点的序列号（用来保证使用最新路由 防止路由环） ，在目的节点序列号相同的情况下，采用跳数较小的。在这种情况下就更新路由表。/若需要更新, 更新路由表项rt_update(rt0, rq-rq_src_seqno, rq-rq_hop_count, ih-saddr()
5、,max(rt0-rt_expire, (CURRENT_TIME + REV_ROUTE_LIFE) );if (rt0-rt_req_timeout 0.0) / Reset the soft state and / Set expiry time to CURRENT_TIME + ACTIVE_ROUTE_TIMEOUT/ This is because route is used in the forward direction, / but only sources get benefited by this changert0-rt_req_cnt = 0;rt0-rt_req_
6、timeout = 0.0; rt0-rt_req_last_ttl = rq-rq_hop_count;rt0-rt_expire = CURRENT_TIME + ACTIVE_ROUTE_TIMEOUT;/判断节点是否有发往反向路由目的节点的数据分组，并且路由是否有效/* Find out whether any buffered packet can benefit from the * reverse route.* May need some change in the following code - Mahesh 09/11/99*/assert (rt0-rt_flags =
7、 RTF_UP);/若有发往反向路由目的节点 的分组Packet *buffered_pkt;while (buffered_pkt = rqueue.deque(rt0-rt_dst) if (rt0 & (rt0-rt_flags = RTF_UP) /若路由有效assert(rt0-rt_hops != INFINITY2);/将数据分组转发forward(rt0, buffered_pkt, NO_DELAY); / End for putting reverse route in rt table/*=*/若没有发往反向路由目的节点的数据分组，或者路由无效/或者原来的路由项不需要更新
8、，转发或处理路由请求分组* We have taken care of the reverse route stuff.* Now see whether we can send a route reply. */* 在这种情况下我们有两种选择，一种是将 RREQ 继续传播下去，一种是产生 RREP。在这之前我们要确定，反向路由已经在路由表中存在。如果存在反向路由，在考虑是否应该想源节点发送 RREP */ rt = rtable.rt_lookup(rq-rq_dst);/判断节点本身是路由请求分组的目的地址if(rq-rq_dst = index) /如果节点本身是目的地址，向源节点发送路
9、由应答分组并且回收请求分组#ifdef DEBUGfprintf(stderr, %d - %s: destination sending replyn,index, _FUNCTION_);#endif / DEBUGseqno = max(seqno, rq-rq_dst_seqno)+1;if (seqno%2) seqno+;sendReply(rq-rq_src, / IP Destination1, / Hop Countindex, / Dest IP Addressseqno, / Dest Sequence NumMY_ROUTE_TIMEOUT, / Lifetimerq-
10、rq_timestamp); / timestampPacket:free(p);/*=*/判断节点是否有到达目的节点足够新的路由？else if (rt & (rt-rt_hops != INFINITY2) & (rt-rt_seqno = rq-rq_dst_seqno) ) /如果不是目的地址，但是有足够新的路由/assert (rt-rt_flags = RTF_UP); assert(rq-rq_dst = rt-rt_dst);/assert (rt-rt_seqno%2) = 0); / is the seqno even?/向源节点发送路由应答分组sendReply(rq-r
11、q_src,rt-rt_hops + 1, /如果是目的节点的话就设成一，这里不是目的节点就在个 RREQ 中的跳数加 1；rq-rq_dst, /如果是目的节点这一项就是目的节点的 IP 地址（这个节点本身的地址） ， 这里是 RREQ 中的目的节点 IP 地址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/ precu
12、rsor lists of destination and source respectively/ /更新正向路由项和反向路由项的前驱列表rt-pc_insert(rt0-rt_nexthop); / nexthop to RREQ sourcert0-pc_insert(rt-rt_nexthop); / nexthop to RREQ destination#ifdef RREQ_GRAT_RREP / /向目的节点发送路由应答分组，并且回收路由请求分组sendReply(rq-rq_dst,rq-rq_hop_count,rq-rq_src,rq-rq_src_seqno,(u_int
13、32_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 dynam
14、ically used and is always set or reset in aodv-packet.h - Anant Utgikar, 09/16/02.Packet:free(p);/*=*/ /* Cant reply. So forward the Route Request*/如果没有到达目的节点足够新的路由，继续转发路由请求分组else ih-saddr() = index;ih-daddr() = IP_BROADCAST;rq-rq_hop_count += 1; / Maximum sequence number seen en routeif (rt) rq-rq_dst_seqno = max(rt-rt_seqno, rq-rq_dst_seqno);forward(aodv_rt_entry*) 0, p, DELAY);/*=
