ntp_peer.c

网络时间协议NTP 源码 版本v4.2.0b 该源码用于linux平台下

	 * We do a dirty little jig to figure the cast flags. This is
	 * probably not the best place to do this, at least until the
	 * configure code is rebuilt. Note only one flag can be set.
	 */
	switch (hmode) {

	case MODE_BROADCAST:
		if(srcadr->ss_family == AF_INET) {
			if (IN_CLASSD(ntohl(((struct sockaddr_in*)srcadr)->sin_addr.s_addr)))
				cast_flags = MDF_MCAST;
			else
				cast_flags = MDF_BCAST;
			break;
		}
		else {
                        if (IN6_IS_ADDR_MULTICAST(&((struct sockaddr_in6*)srcadr)->sin6_addr))
        	                cast_flags = MDF_MCAST;
	        	else
                        	cast_flags = MDF_BCAST;
                	break;
                }

	case MODE_CLIENT:
		if(srcadr->ss_family == AF_INET) {
			if (IN_CLASSD(ntohl(((struct sockaddr_in*)srcadr)->sin_addr.s_addr)))
				cast_flags = MDF_ACAST;
			else
				cast_flags = MDF_UCAST;
			break;
		}
		else {
			if (IN6_IS_ADDR_MULTICAST(&((struct sockaddr_in6*)srcadr)->sin6_addr))
				cast_flags = MDF_ACAST;
			else
				cast_flags = MDF_UCAST;
			break;
		}

	default:
		cast_flags = MDF_UCAST;
	}

	/*
	 * If the peer is already configured, some dope has a duplicate
	 * configureation entry or another dope is wiggling from afar.
	 */
	if (peer != 0) {
		peer->hmode = (u_char)hmode;
		peer->version = (u_char) version;
		peer->minpoll = (u_char) minpoll;
		peer->maxpoll = (u_char) maxpoll;
		peer->flags = flags | FLAG_CONFIG |
			(peer->flags & FLAG_REFCLOCK);
		peer->cast_flags = cast_flags;
		peer->ttl = (u_char) ttl;
		peer->keyid = key;
		peer->precision = sys_precision;
		peer_clear(peer, "RMOT");
		return (peer);
	}

	/*
	 * Here no match has been found, so presumably this is a new
	 * persistent association. Mobilize the thing and initialize its
	 * variables. If emulating ntpdate, force iburst.
	 */
	if (mode_ntpdate)
		flags |= FLAG_IBURST;
	peer = newpeer(srcadr, dstadr, hmode, version, minpoll, maxpoll,
	    flags | FLAG_CONFIG, cast_flags, ttl, key);
	return (peer);
}


/*
 * newpeer - initialize a new peer association
 */
struct peer *
newpeer(
	struct sockaddr_storage *srcadr,
	struct interface *dstadr,
	int hmode,
	int version,
	int minpoll,
	int maxpoll,
	u_int flags,
	u_char cast_flags,
	int ttl,
	keyid_t key
	)
{
	register struct peer *peer;
	register int i;
#ifdef OPENSSL
	char	statstr[NTP_MAXSTRLEN]; /* statistics for filegen */
#endif /* OPENSSL */

	/*
	 * Allocate a new peer structure. Some dirt here, since some of
	 * the initialization requires knowlege of our system state.
	 */
	if (peer_free_count == 0)
		getmorepeermem();
	peer = peer_free;
	peer_free = peer->next;
	peer_free_count--;
	peer_associations++;
	if (flags & FLAG_PREEMPT)
		peer_preempt++;
	memset((char *)peer, 0, sizeof(struct peer));

	/*
	 * Assign an association ID and increment the system variable.
	 */
	peer->associd = current_association_ID;
	if (++current_association_ID == 0)
		++current_association_ID;

#ifdef DEBUG
	if (debug >2)
		printf("newpeer: cast flags: 0x%x for address: %s\n",
			cast_flags, stoa(srcadr));
#endif
	/*
	 * Initialize the peer structure and dance the interface jig.
	 * Reference clocks step the loopback waltz, the others
	 * squaredance around the interface list looking for a buddy. If
	 * the dance peters out, there is always the wildcard interface.
	 * This might happen in some systems and would preclude proper
	 * operation with public key cryptography.
	 */
	if (ISREFCLOCKADR(srcadr))
		peer->dstadr = loopback_interface;
	else if (cast_flags & (MDF_BCLNT | MDF_ACAST | MDF_MCAST | MDF_BCAST)) {
		peer->dstadr = findbcastinter(srcadr);
#ifdef DEBUG
		if (debug > 1) {
			if (peer->dstadr != NULL)
				printf("Found broadcast interface address %s, for address %s\n",
					stoa(&(peer->dstadr)->sin), stoa(srcadr));
			else
				printf("No broadcast local address found for address %s\n",
					stoa(srcadr));
		}
#endif
		/*
		 * If it was a multicast packet, findbcastinter() may not
		 * find it, so try a little harder.
		 */
		if (peer->dstadr == ANY_INTERFACE_CHOOSE(srcadr))
			peer->dstadr = findinterface(srcadr);
	} else if (dstadr != NULL && dstadr != ANY_INTERFACE_CHOOSE(srcadr))
		peer->dstadr = dstadr;
	else
		peer->dstadr = findinterface(srcadr);

	/*
	 * If we can't find an interface to use we return a NULL
	 */
	if (peer->dstadr == NULL)
	{
		msyslog(LOG_ERR, "Cannot find suitable interface for address %s", stoa(srcadr));
		return (NULL);
	}
	/*
	 * Broadcast needs the socket enabled for broadcast
	 */
	if (cast_flags & MDF_BCAST) {
		enable_broadcast(peer->dstadr, srcadr);
	}
	/*
	 * Multicast needs the socket interface enabled for multicast
	 */
	if (cast_flags & MDF_MCAST) {
		enable_multicast_if(peer->dstadr, srcadr);
	}
#ifdef DEBUG
	if (debug>2)
		printf("newpeer: using fd %d and our addr %s\n",
		    peer->dstadr->fd, stoa(&peer->dstadr->sin));
#endif
	peer->srcadr = *srcadr;
	peer->hmode = (u_char)hmode;
	peer->version = (u_char)version;
	peer->minpoll = (u_char)max(NTP_MINPOLL, minpoll);
	peer->maxpoll = (u_char)min(NTP_MAXPOLL, maxpoll);
	peer->flags = flags;
	if (key != 0)
		peer->flags |= FLAG_AUTHENABLE;
	if (key > NTP_MAXKEY)
		peer->flags |= FLAG_SKEY;
	peer->cast_flags = cast_flags;
	peer->ttl = (u_char)ttl;
	peer->keyid = key;
	peer->precision = sys_precision;
	peer->hpoll = peer->minpoll;
	if (cast_flags & MDF_ACAST)
		peer_clear(peer, "ACST");
	else if (cast_flags & MDF_MCAST)
		peer_clear(peer, "MCST");
	else if (cast_flags & MDF_BCAST)
		peer_clear(peer, "BCST");
	else
		peer_clear(peer, "INIT");
	if (mode_ntpdate)
		peer_ntpdate++;

	/*
	 * Note time on statistics timers.
	 */
	peer->timereset = current_time;
	peer->timereachable = current_time;
	peer->timereceived = current_time;
#ifdef REFCLOCK
	if (ISREFCLOCKADR(&peer->srcadr)) {

		/*
		 * We let the reference clock support do clock
		 * dependent initialization.  This includes setting
		 * the peer timer, since the clock may have requirements
		 * for this.
		 */
		if (!refclock_newpeer(peer)) {
			/*
			 * Dump it, something screwed up
			 */
			peer->next = peer_free;
			peer_free = peer;
			peer_free_count++;
			return (NULL);
		}
	}
#endif

	/*
	 * Put the new peer in the hash tables.
	 */
	i = NTP_HASH_ADDR(&peer->srcadr);
	peer->next = peer_hash[i];
	peer_hash[i] = peer;
	peer_hash_count[i]++;
	i = peer->associd & NTP_HASH_MASK;
	peer->ass_next = assoc_hash[i];
	assoc_hash[i] = peer;
	assoc_hash_count[i]++;
#ifdef OPENSSL
	if (peer->flags & FLAG_SKEY) {
		sprintf(statstr, "newpeer %d", peer->associd);
		record_crypto_stats(&peer->srcadr, statstr);
#ifdef DEBUG
		if (debug)
			printf("peer: %s\n", statstr);
#endif
	}
#endif /* OPENSSL */
#ifdef DEBUG
	if (debug)
		printf(
		    "newpeer: %s->%s mode %d vers %d poll %d %d flags 0x%x 0x%x ttl %d key %08x\n",
		    peer->dstadr == NULL ? "null" : stoa(&peer->dstadr->sin),
		    stoa(&peer->srcadr),
		    peer->hmode, peer->version, peer->minpoll,
		    peer->maxpoll, peer->flags, peer->cast_flags,
		    peer->ttl, peer->keyid);
#endif
	return (peer);
}


/*
 * peer_unconfig - remove the configuration bit from a peer
 */
int
peer_unconfig(
	struct sockaddr_storage *srcadr,
	struct interface *dstadr,
	int mode
	)
{
	register struct peer *peer;
	int num_found;

	num_found = 0;
	peer = findexistingpeer(srcadr, (struct peer *)0, mode);
	while (peer != 0) {
		if (peer->flags & FLAG_CONFIG
		    && (dstadr == 0 || peer->dstadr == dstadr)) {
			num_found++;

			/*
			 * Tricky stuff here. If the peer is polling us
			 * in active mode, turn off the configuration
			 * bit and make the mode passive. This allows us
			 * to avoid dumping a lot of history for peers
			 * we might choose to keep track of in passive
			 * mode. The protocol will eventually terminate
			 * undesirables on its own.
			 */
			if (peer->hmode == MODE_ACTIVE
			    && peer->pmode == MODE_ACTIVE) {
				peer->hmode = MODE_PASSIVE;
				peer->flags &= ~FLAG_CONFIG;
			} else {
				unpeer(peer);
				peer = 0;
			}
		}
		peer = findexistingpeer(srcadr, peer, mode);
	}
	return (num_found);
}

/*
 * peer_clr_stats - clear peer module stat counters
 */
void
peer_clr_stats(void)
{
	findpeer_calls = 0;
	assocpeer_calls = 0;
	peer_allocations = 0;
	peer_demobilizations = 0;
	peer_timereset = current_time;
}

/*
 * peer_reset - reset stat counters in a peer structure
 */
void
peer_reset(
	struct peer *peer
	)
{
	if (peer == 0)
	    return;
	peer->sent = 0;
	peer->received = 0;
	peer->processed = 0;
	peer->badauth = 0;
	peer->bogusorg = 0;
	peer->oldpkt = 0;
	peer->seldisptoolarge = 0;
	peer->timereset = current_time;
}


/*
 * peer_all_reset - reset all peer stat counters
 */
void
peer_all_reset(void)
{
	struct peer *peer;
	int hash;

	for (hash = 0; hash < NTP_HASH_SIZE; hash++)
	    for (peer = peer_hash[hash]; peer != 0; peer = peer->next)
		peer_reset(peer);
}


#ifdef OPENSSL
/*
 * expire_all - flush all crypto data and update timestamps.
 */
void
expire_all(void)
{
	struct peer *peer, *next_peer;
	int n;

	/*
	 * This routine is called about once per day from the timer
	 * routine and when the client is first synchronized. Search the
	 * peer list for all associations and flush only the key list
	 * and cookie. If a manycast client association, flush
	 * everything. Then, recompute and sign the agreement public
	 * value, if present.
	 */
	if (!crypto_flags)
		return;

	for (n = 0; n < NTP_HASH_SIZE; n++) {
		for (peer = peer_hash[n]; peer != 0; peer = next_peer) {
			next_peer = peer->next;
			if (!(peer->flags & FLAG_SKEY)) {
				continue;

			} else if (peer->hmode == MODE_ACTIVE ||
			    peer->hmode == MODE_PASSIVE) {
				key_expire(peer);
				peer->crypto &= ~(CRYPTO_FLAG_AUTO |
				    CRYPTO_FLAG_AGREE);
			}
				
		}
	}
	RAND_bytes((u_char *)&sys_private, 4);
	crypto_update();
}
#endif /* OPENSSL */


/*
 * findmanycastpeer - find and return a manycast peer
 */
struct peer *
findmanycastpeer(
	struct recvbuf *rbufp
	)
{
	register struct peer *peer;
	struct pkt *pkt;
	l_fp p_org;
	int i;

 	/*
 	 * This routine is called upon arrival of a server-mode message
	 * from a manycast client. Search the peer list for a manycast
	 * client association where the last transmit timestamp matches
	 * the originate timestamp. This assumes the transmit timestamps
	 * for possibly more than one manycast association are unique.
	 */
	pkt = &rbufp->recv_pkt;
	for (i = 0; i < NTP_HASH_SIZE; i++) {
		if (peer_hash_count[i] == 0)
			continue;

		for (peer = peer_hash[i]; peer != 0; peer =
		    peer->next) {
			if (peer->cast_flags & MDF_ACAST) {
				NTOHL_FP(&pkt->org, &p_org);
				if (L_ISEQU(&peer->xmt, &p_org))
					return (peer);
			}
		}
	}
	return (NULL);
}