aodv_hello.c

aodv协议的实现 使用linux环境下的c++编写

/*****************************************************************************
 *
 * Copyright (C) 2001 Uppsala University and Ericsson AB.
 *
 * 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
 *
 * Authors: Erik Nordstr鰉, <[e-mail]>
 *          
 *
 *****************************************************************************/

#ifdef NS_PORT
#include "aodv-uu.h"
#else
#include <netinet/in.h>
#include "aodv_hello.h"
#include "aodv_timeout.h"
#include "aodv_rrep.h"
#include "aodv_rreq.h"
#include "routing_table.h"
#include "timer_queue.h"
#include "params.h"
#include "aodv_socket.h"
#include "defs.h"
#include "debug.h"

extern int unidir_hack, receive_n_hellos, hello_jittering, optimized_hellos;
static struct timer hello_timer;

#endif

/* #define DEBUG_HELLO */


long NS_CLASS hello_jitter()
{
    if (hello_jittering) {
#ifdef NS_PORT
	return (long) (((float) Random::integer(RAND_MAX + 1) / RAND_MAX - 0.5)
		       * JITTER_INTERVAL);
#else
	return (long) (((float) random() / RAND_MAX - 0.5) * JITTER_INTERVAL);
#endif
    } else
	return 0;
}

void NS_CLASS hello_start()
{
    if (hello_timer.used)
	return;

    gettimeofday(&this_host.fwd_time, NULL);

    DEBUG(LOG_DEBUG, 0, "Starting to send HELLOs!");
    timer_init(&hello_timer, &NS_CLASS hello_send, NULL);

    hello_send(NULL);
}

void NS_CLASS hello_stop()
{
    DEBUG(LOG_DEBUG, 0, "No active forwarding routes - stopped sending HELLOs!");
    timer_remove(&hello_timer);
}

void NS_CLASS hello_send(void *arg)
{
    RREP *rrep;
    AODV_ext *ext = NULL;
    u_int8_t flags = 0;
    struct in_addr dest;
    long time_diff, jitter;
    struct timeval now;
    int msg_size = RREP_SIZE;
    int i;

    gettimeofday(&now, NULL);
    
    if (optimized_hellos && 
	timeval_diff(&now, &this_host.fwd_time) > ACTIVE_ROUTE_TIMEOUT) {
	hello_stop();
	return;
    }

    time_diff = timeval_diff(&now, &this_host.bcast_time);
    jitter = hello_jitter();

    /* This check will ensure we don't send unnecessary hello msgs, in case
       we have sent other bcast msgs within HELLO_INTERVAL */
    if (time_diff >= HELLO_INTERVAL) {

	for (i = 0; i < MAX_NR_INTERFACES; i++) {
	    if (!DEV_NR(i).enabled)
		continue;
#ifdef DEBUG_HELLO
	    DEBUG(LOG_DEBUG, 0, "sending Hello to 255.255.255.255");
#endif
	    rrep = rrep_create(flags, 0, 0, DEV_NR(i).ipaddr,
			       this_host.seqno,
			       DEV_NR(i).ipaddr,
			       ALLOWED_HELLO_LOSS * HELLO_INTERVAL);

	    /* Assemble a RREP extension which contain our neighbor set... */
	    if (unidir_hack) {
		int i;
		
		if (ext)
		    ext = AODV_EXT_NEXT(ext);
		else
		    ext = (AODV_ext *) ((char *) rrep + RREP_SIZE);
		
		ext->type = RREP_HELLO_NEIGHBOR_SET_EXT;
		ext->length = 0;

		for (i = 0; i < RT_TABLESIZE; i++) {
		    list_t *pos;
		    list_foreach(pos, &rt_tbl.tbl[i]) {
			rt_table_t *rt = (rt_table_t *)pos;
			/* If an entry has an active hello timer, we assume
			   that we are receiving hello messages from that
			   node... */
			if (rt->hello_timer.used) {
#ifdef DEBUG_HELLO
			    DEBUG(LOG_INFO, 0,
				  "Adding %s to hello neighbor set ext",
				  ip_to_str(rt->dest_addr));
#endif
			    memcpy(AODV_EXT_NEXT(ext), &rt->dest_addr, sizeof(struct in_addr));
			    ext->length += sizeof(struct in_addr);
			}
		    }
		}
		if (ext->length)
		    msg_size = RREP_SIZE + AODV_EXT_SIZE(ext);
	    }
	    dest.s_addr = AODV_BROADCAST;
	    aodv_socket_send((AODV_msg *) rrep, dest, msg_size,
			     1, &DEV_NR(i));
	}

	timer_set_timeout(&hello_timer, HELLO_INTERVAL + jitter);
    } else {
	if (HELLO_INTERVAL - time_diff + jitter < 0)
	    timer_set_timeout(&hello_timer,
			      HELLO_INTERVAL - time_diff - jitter);
	else
	    timer_set_timeout(&hello_timer,
			      HELLO_INTERVAL - time_diff + jitter);
    }
}


/* Process a hello message */
void NS_CLASS hello_process(RREP * hello, int rreplen, unsigned int ifindex)
{
    u_int32_t hello_seqno, timeout, hello_interval = HELLO_INTERVAL;
    u_int8_t state, flags = 0;
    struct in_addr ext_neighbor, hello_dest;
    rt_table_t *rt;
    AODV_ext *ext = NULL;
    int i;
    struct timeval now;

    gettimeofday(&now, NULL);

    hello_dest.s_addr = hello->dest_addr;
    hello_seqno = ntohl(hello->dest_seqno);

    if (unidir_hack)
	flags |= RT_UNIDIR;
    
    /* Check for hello interval extension: */
    ext = (AODV_ext *) ((char *) hello + RREP_SIZE);

    while (rreplen > (int) RREP_SIZE) {
	switch (ext->type) {
	case RREP_HELLO_INTERVAL_EXT:
	    if (ext->length == 4) {
		memcpy(&hello_interval, AODV_EXT_DATA(ext), 4);
		hello_interval = ntohl(hello_interval);
#ifdef DEBUG_HELLO
		DEBUG(LOG_INFO, 0, "Hello extension interval=%lu!",
		      hello_interval);
#endif

	    } else
		alog(LOG_WARNING, 0,
		    __FUNCTION__, "Bad hello interval extension!");
	    break;
	case RREP_HELLO_NEIGHBOR_SET_EXT:

#ifdef DEBUG_HELLO
	    DEBUG(LOG_INFO, 0, "RREP_HELLO_NEIGHBOR_SET_EXT");
#endif
	    for (i = 0; i < ext->length; i = i + 4) {
		ext_neighbor.s_addr = *(in_addr_t *)((char *) AODV_EXT_DATA(ext) + i);

		if (ext_neighbor.s_addr == DEV_IFINDEX(ifindex).ipaddr.s_addr)
		    flags &= ~RT_UNIDIR;
	    }
	    break;
	default:
	    alog(LOG_WARNING, 0, __FUNCTION__,
		"Bad extension!! type=%d, length=%d", ext->type, ext->length);
	    ext = NULL;
	    break;
	}
	if (ext == NULL)
	    break;

	rreplen -= AODV_EXT_SIZE(ext);
	ext = AODV_EXT_NEXT(ext);
    }

#ifdef DEBUG_HELLO
    DEBUG(LOG_DEBUG, 0, "rcvd HELLO from %s, seqno %lu",
	  ip_to_str(hello_dest), hello_seqno);
#endif
    /* This neighbor should only be valid after receiving 3
       consecutive hello messages... */
    if (receive_n_hellos)
	state = INVALID;
    else
	state = VALID;

    timeout = ALLOWED_HELLO_LOSS * hello_interval + ROUTE_TIMEOUT_SLACK;

    if ((rt = rt_table_find(hello_dest)) == NULL) {
	/* No active or expired route in the routing table. So we add a
	   new entry... */
	
	rt = rt_table_insert(hello_dest, hello_dest, 1, 
			     hello_seqno, timeout, state, flags, ifindex);
	
	if (flags & RT_UNIDIR) {
	    DEBUG(LOG_INFO, 0, "%s new NEIGHBOR, link UNI-DIR",
	      ip_to_str(rt->dest_addr));
	} else {
	    DEBUG(LOG_INFO, 0, "%s new NEIGHBOR!", ip_to_str(rt->dest_addr));
	}
	rt->hello_cnt = 1;

    } else {

	if ((flags & RT_UNIDIR) && rt->state == VALID && rt->hcnt > 1) {
	    goto hello_update;
	}

	if (receive_n_hellos && rt->hello_cnt < (receive_n_hellos - 1)) {
	    if (timeval_diff(&now, &rt->last_hello_time) <
		(long) (hello_interval + hello_interval / 2))
		rt->hello_cnt++;
	    else
		rt->hello_cnt = 1;

	    rt->last_hello_time = now;
	    return;
	}
	rt_table_update(rt, hello_dest, 1, hello_seqno, timeout, VALID, 
			flags | rt->flags);
    }

  hello_update:

    hello_update_timeout(rt, &now, ALLOWED_HELLO_LOSS * hello_interval);
    return;
}


#define HELLO_DELAY 50		/* The extra time we should allow an hello
				   message to take (due to processing) before
				   assuming lost . */

NS_INLINE void NS_CLASS hello_update_timeout(rt_table_t * rt, struct timeval *now, long time)
{
    timer_set_timeout(&rt->hello_timer, time + HELLO_DELAY);
    rt->last_hello_time = *now;
}