rerr.c

ucsb大学开发的aodv路由协议代码。

/*
 * Copyright (C) 2001, University of California, Santa Barbara
 * 
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 * 
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
 * 
 * Other copyrights might apply to parts of this software and are so
 * noted when applicable.
 */

/*
 * Parts of this program has been derived from PIM sparse-mode pimd.
 * The pimd program is covered by the license in the accompanying file
 * named "LICENSE.pimd".
 *  
 * The pimd program is COPYRIGHT 1998 by University of Southern California.
 *
 */
#include <arpa/inet.h>
#include <netinet/in.h>
#include <string.h>
#include <sys/socket.h>
#include <sys/types.h>

#include "aodvConst.h"
#include "aodvMsg.h"
#include "aodvPktInfo.h"
#include "aodvSocket.h"
#include "const.h"
#include "debug.h"
#include "inet.h"
#include "localRepair.h"
#include "rerr.h"
#include "routingTable.h"
#include "sendDatagram.h"

int localRepair = FALSE;

static void fill_rerr(struct RERR *rerr, int N){
  trace(TRACE_RERR,"fill_rerr");
  rerr->type=AODV_RERR;
  rerr->N=N;
  rerr->reserved1=0;
  rerr->reserved2=0;
  rerr->destCount=0;
  rerr->unreachables=NULL;
}

void sendRERR(struct RERR *rerr){
  struct AodvPktInfo info;
  int intermediateN;
  int i;
  int datalen;
  char *data;
  struct UnreachableDest *cur;
  
  trace(TRACE_RERR,"sending RERR");
  
  printRERR(rerr);

  //kind of a pain because we have the linked list of unreachables.
  //we have to create a buffer to send, then remove it afterward.
  //4 = size of RERR
  datalen = 4 + 8 * rerr->destCount;
  //malloc data
  data = (char *)malloc(datalen);
  
  //fill in the data
  data[0]=rerr->type;
  intermediateN = rerr->N;
  intermediateN = intermediateN << 7;
  data[1]=intermediateN;
  data[2]=rerr->reserved2;
  data[3]=rerr->destCount;
  for(i = 0, cur = rerr->unreachables
	; (i < rerr->destCount) && (cur != NULL)
	; i++, cur = cur->next) {
    memcpy(data + 4 + i * 8, &(cur->unreachableDest), 4);
    memcpy(data + 8 + i * 8, &(cur->unreachableDestSeqNum), 4);
  }
  
  fill_pktInfo(&info,BROADCAST);
  
  if(datalen >= 12){
    trace(TRACE_METRIC,"s RERR");
    sendDatagram(&info,data,datalen);
  }

  //free data
  free(data);
}

void assembleRERR(char *data, struct RERR *rerr){
  int intermediateN;
  int i;
  int destCount;
  u_int32_t unreachableDest;
  u_int32_t unreachableDestSeqNum;

  trace(TRACE_RERR,"assembleRERR");
  
  //this should reverse the sending process
  rerr->type = data[0];
  intermediateN = data[1];
  intermediateN = intermediateN >> 7;
  rerr->N = intermediateN;
  rerr->reserved2 = data[2];
  destCount = data[3];
  rerr->unreachables = NULL;
  for (i = 0
	 ; i < destCount
	 ; i++ ) {
    memcpy(&unreachableDest, data + 4 + i * 8, 4);
    memcpy(&unreachableDestSeqNum, data + 8 + i * 8, 4);
    //trace(TRACE_RERR,"assembleRERR:i=%i",i);
    //trace(TRACE_RERR,"assembleRERR:rerr->destcount=%u"
    //,rerr->destCount);
    //trace(TRACE_RERR,"assembleRERR:unreachableDest=%s"
    //	,inet_fmt_n(unreachableDest,s1));
    //trace(TRACE_RERR,"assembleRERR:unreachableDestSeqNum=%u"
    //	,unreachableDestSeqNum);
    appendUnreachable(rerr
		      , ntohl(unreachableDest)
		      , ntohl(unreachableDestSeqNum));
  }
}

void deleteRERRUnreachables(struct RERR *rerr){
  struct UnreachableDest *cur;
  struct UnreachableDest *next;
  
  trace(TRACE_RERR,"deleteRERRUnreachables");
  
  for(cur = rerr->unreachables
	; (rerr->unreachables != NULL) && (cur != NULL) 
	; cur = next ) {
    if((rerr->unreachables != NULL) && (cur != NULL)){
      next = cur->next;
    }
    //free unreachableDest
    free(cur);
  }
}

void appendUnreachable(struct RERR *rerr
			      , u_int32_t dest
			      , u_int32_t destSeqNum){
  struct UnreachableDest *first = NULL;
  struct UnreachableDest *new_u = NULL;
  
  trace(TRACE_RERR,"appendUnreachable");
  rerr->destCount++;
  first = rerr->unreachables;
  //malloc UnreachableDest
  new_u = (struct UnreachableDest *)malloc(sizeof(struct UnreachableDest));
  if(new_u == NULL){
    log(LOG_ERR,TRUE,"unable to allocate memory, UnreachableDest");
  }
  new_u->unreachableDest=htonl(dest);
  new_u->unreachableDestSeqNum=htonl(destSeqNum);
  new_u->next=first;
  rerr->unreachables=new_u;
}


void createAndSendRERR(u_int32_t broken,int N){
  struct RERR rerr;
  mySeqNum++;
  trace(TRACE_RT,"Increasing SeqNum to %d because sending RERR",mySeqNum);
  trace(TRACE_RERR|TRACE_DEMO
	,"send RERR, broken link to %s"
	,inet_fmt_h(broken,s1));
  
  //create RERR
  fill_rerr(&rerr,N);
  
  //also increments DestSeqNum for anyone who has the broken as nextHop
  //and expires each unreachable route
  appendUnreachables(&rerr,broken);
  removeBrokenFromPrecursors(broken);
  sendRERR(&rerr);
  deleteRERRUnreachables(&rerr);
}

void generateRERR(u_int32_t broken){
  int hopCount;
  trace(TRACE_RERR,"generateRERR");
  
  hopCount=getHopCount(broken);
  if(hopCount == DELETE_ROUTE){
    //don't genreate RERR, we already have
    return;
  }
  if((localRepair == TRUE) 
     && (hopCount != -1) 
     && (hopCount <= MAX_REPAIR_TTL)) {
    
    //attempt to repair locally
    repairLocally(broken); //in localRepair

  } else {
    createAndSendRERR(broken,0);
  }
}

void receiveRERR(u_int32_t src, char *raw){
  struct RERR rerr;
  struct RERR new_rerr;
  
  updateNeighbor(src,0);

  //need to reassemble RREQ, unreachables aren't right.
  assembleRERR(raw, &rerr);
  
  trace(TRACE_RERR|TRACE_DEMO, "received RERR from %s",inet_fmt_h(src,s1));
  printRERR(&rerr);
  trace(TRACE_RERR|TRACE_DEMO
	,"received RERR first unreachable is %s"
	,inet_fmt_n(rerr.unreachables->unreachableDest,s1));
  
  if(rerr.N == 1){
    //TODO FUTURE local repair rerr messages
    return;
  } else {

    fill_rerr(&new_rerr,0);
    
    if(processRERR(src, &rerr, &new_rerr) == TRUE){
      sendRERR(&new_rerr);
    }
    deleteRERRUnreachables(&rerr);
    deleteRERRUnreachables(&new_rerr);
  }
}