Ejemplo n.º 1
0
int do_one_request(struct nlmsghdr *n)
{
	struct ndmsg *ndm = NLMSG_DATA(n);
	int len = n->nlmsg_len;
	struct rtattr * tb[NDA_MAX+1];
	struct dbkey key;
	DBT dbkey, dbdat;
	int do_acct = 0;

	if (n->nlmsg_type == NLMSG_DONE) {
		dbase->sync(dbase, 0);

		/* Now we have at least mirror of kernel db, so that
		 * may start real resolution.
		 */
		do_sysctl_adjustments();
		return 0;
	}

	if (n->nlmsg_type != RTM_GETNEIGH && n->nlmsg_type != RTM_NEWNEIGH)
		return 0;

	len -= NLMSG_LENGTH(sizeof(*ndm));
	if (len < 0)
		return -1;

	if (ndm->ndm_family != AF_INET ||
	    (ifnum && !handle_if(ndm->ndm_ifindex)) ||
	    ndm->ndm_flags ||
	    ndm->ndm_type != RTN_UNICAST ||
	    !(ndm->ndm_state&~NUD_NOARP))
		return 0;

	parse_rtattr(tb, NDA_MAX, NDA_RTA(ndm), len);

	if (!tb[NDA_DST])
		return 0;

	key.iface = ndm->ndm_ifindex;
	memcpy(&key.addr, RTA_DATA(tb[NDA_DST]), 4);
	dbkey.data = &key;
	dbkey.size = sizeof(key);

	if (dbase->get(dbase, &dbkey, &dbdat, 0) != 0) {
		dbdat.data = 0;
		dbdat.size = 0;
	}

	if (n->nlmsg_type == RTM_GETNEIGH) {
		if (!(n->nlmsg_flags&NLM_F_REQUEST))
			return 0;

		if (!(ndm->ndm_state&(NUD_PROBE|NUD_INCOMPLETE))) {
			stats.app_bad++;
			return 0;
		}

		if (ndm->ndm_state&NUD_PROBE) {
			/* If we get this, kernel still has some valid
			 * address, but unicast probing failed and host
			 * is either dead or changed its mac address.
			 * Kernel is going to initiate broadcast resolution.
			 * OK, we invalidate our information as well.
			 */
			if (dbdat.data && !IS_NEG(dbdat.data))
				stats.app_neg++;

			dbase->del(dbase, &dbkey, 0);
		} else {
			/* If we get this kernel does not have any information.
			 * If we have something tell this to kernel. */
			stats.app_recv++;
			if (dbdat.data && !IS_NEG(dbdat.data)) {
				stats.app_success++;
				respond_to_kernel(key.iface, key.addr, dbdat.data, dbdat.size);
				return 0;
			}

			/* Sheeit! We have nothing to tell. */
			/* If we have recent negative entry, be silent. */
			if (dbdat.data && NEG_VALID(dbdat.data)) {
				if (NEG_CNT(dbdat.data) >= active_probing) {
					stats.app_suppressed++;
					return 0;
				}
				do_acct = 1;
			}
		}

		if (active_probing &&
		    queue_active_probe(ndm->ndm_ifindex, key.addr) == 0 &&
		    do_acct) {
			NEG_CNT(dbdat.data)++;
			dbase->put(dbase, &dbkey, &dbdat, 0);
		}
	} else if (n->nlmsg_type == RTM_NEWNEIGH) {
		if (n->nlmsg_flags&NLM_F_REQUEST)
			return 0;

		if (ndm->ndm_state&NUD_FAILED) {
			/* Kernel was not able to resolve. Host is dead.
			 * Create negative entry if it is not present
			 * or renew it if it is too old. */
			if (!dbdat.data ||
			    !IS_NEG(dbdat.data) ||
			    !NEG_VALID(dbdat.data)) {
				__u8 ndata[6];
				stats.kern_neg++;
				prepare_neg_entry(ndata, time(NULL));
				dbdat.data = ndata;
				dbdat.size = sizeof(ndata);
				dbase->put(dbase, &dbkey, &dbdat, 0);
			}
		} else if (tb[NDA_LLADDR]) {
			if (dbdat.data && !IS_NEG(dbdat.data)) {
				if (memcmp(RTA_DATA(tb[NDA_LLADDR]), dbdat.data, dbdat.size) == 0)
					return 0;
				stats.kern_change++;
			} else {
				stats.kern_new++;
			}
			dbdat.data = RTA_DATA(tb[NDA_LLADDR]);
			dbdat.size = RTA_PAYLOAD(tb[NDA_LLADDR]);
			dbase->put(dbase, &dbkey, &dbdat, 0);
		}
	}
	return 0;
}
Ejemplo n.º 2
0
static int send_probe(int ifindex, __u32 addr)
{
	struct ifreq ifr = { .ifr_ifindex = ifindex };
	struct sockaddr_in dst = {
		.sin_family = AF_INET,
		.sin_port = htons(1025),
		.sin_addr.s_addr = addr,
	};
	socklen_t len;
	unsigned char buf[256];
	struct arphdr *ah = (struct arphdr *)buf;
	unsigned char *p = (unsigned char *)(ah+1);
	struct sockaddr_ll sll = {
		.sll_family = AF_PACKET,
		.sll_ifindex = ifindex,
		.sll_protocol = htons(ETH_P_ARP),
	};

	if (ioctl(udp_sock, SIOCGIFNAME, &ifr))
		return -1;
	if (ioctl(udp_sock, SIOCGIFHWADDR, &ifr))
		return -1;
	if (ifr.ifr_hwaddr.sa_family != ARPHRD_ETHER)
		return -1;
	if (setsockopt(udp_sock, SOL_SOCKET, SO_BINDTODEVICE, ifr.ifr_name, strlen(ifr.ifr_name)+1) < 0)
		return -1;

	if (connect(udp_sock, (struct sockaddr *)&dst, sizeof(dst)) < 0)
		return -1;
	len = sizeof(dst);
	if (getsockname(udp_sock, (struct sockaddr *)&dst, &len) < 0)
		return -1;

	ah->ar_hrd = htons(ifr.ifr_hwaddr.sa_family);
	ah->ar_pro = htons(ETH_P_IP);
	ah->ar_hln = 6;
	ah->ar_pln = 4;
	ah->ar_op  = htons(ARPOP_REQUEST);

	memcpy(p, ifr.ifr_hwaddr.sa_data, ah->ar_hln);
	p += ah->ar_hln;

	memcpy(p, &dst.sin_addr, 4);
	p += 4;

	memset(sll.sll_addr, 0xFF, sizeof(sll.sll_addr));
	memcpy(p, &sll.sll_addr, ah->ar_hln);
	p += ah->ar_hln;

	memcpy(p, &addr, 4);
	p += 4;

	if (sendto(pset[0].fd, buf, p-buf, 0, (struct sockaddr *)&sll, sizeof(sll)) < 0)
		return -1;
	stats.probes_sent++;
	return 0;
}

/* Be very tough on sending probes: 1 per second with burst of 3. */

static int queue_active_probe(int ifindex, __u32 addr)
{
	static struct timeval prev;
	static int buckets;
	struct timeval now;

	gettimeofday(&now, NULL);
	if (prev.tv_sec) {
		int diff = (now.tv_sec-prev.tv_sec)*1000+(now.tv_usec-prev.tv_usec)/1000;

		buckets += diff;
	} else {
		buckets = broadcast_burst;
	}
	if (buckets > broadcast_burst)
		buckets = broadcast_burst;
	if (buckets >= broadcast_rate && !send_probe(ifindex, addr)) {
		buckets -= broadcast_rate;
		prev = now;
		return 0;
	}
	stats.probes_suppressed++;
	return -1;
}

static int respond_to_kernel(int ifindex, __u32 addr, char *lla, int llalen)
{
	struct {
		struct nlmsghdr	n;
		struct ndmsg		ndm;
		char			buf[256];
	} req = {
		.n.nlmsg_len = NLMSG_LENGTH(sizeof(struct ndmsg)),
		.n.nlmsg_flags = NLM_F_REQUEST,
		.n.nlmsg_type = RTM_NEWNEIGH,
		.ndm.ndm_family = AF_INET,
		.ndm.ndm_state = NUD_STALE,
		.ndm.ndm_ifindex = ifindex,
		.ndm.ndm_type = RTN_UNICAST,
	};

	addattr_l(&req.n, sizeof(req), NDA_DST, &addr, 4);
	addattr_l(&req.n, sizeof(req), NDA_LLADDR, lla, llalen);
	return rtnl_send(&rth, &req, req.n.nlmsg_len) <= 0;
}

static void prepare_neg_entry(__u8 *ndata, __u32 stamp)
{
	ndata[0] = 0xFF;
	ndata[1] = 0;
	ndata[2] = stamp>>24;
	ndata[3] = stamp>>16;
	ndata[4] = stamp>>8;
	ndata[5] = stamp;
}


static int do_one_request(struct nlmsghdr *n)
{
	struct ndmsg *ndm = NLMSG_DATA(n);
	int len = n->nlmsg_len;
	struct rtattr *tb[NDA_MAX+1];
	struct dbkey key;
	DBT dbkey, dbdat;
	int do_acct = 0;

	if (n->nlmsg_type == NLMSG_DONE) {
		dbase->sync(dbase, 0);

		/* Now we have at least mirror of kernel db, so that
		 * may start real resolution.
		 */
		do_sysctl_adjustments();
		return 0;
	}

	if (n->nlmsg_type != RTM_GETNEIGH && n->nlmsg_type != RTM_NEWNEIGH)
		return 0;

	len -= NLMSG_LENGTH(sizeof(*ndm));
	if (len < 0)
		return -1;

	if (ndm->ndm_family != AF_INET ||
	    (ifnum && !handle_if(ndm->ndm_ifindex)) ||
	    ndm->ndm_flags ||
	    ndm->ndm_type != RTN_UNICAST ||
	    !(ndm->ndm_state&~NUD_NOARP))
		return 0;

	parse_rtattr(tb, NDA_MAX, NDA_RTA(ndm), len);

	if (!tb[NDA_DST])
		return 0;

	key.iface = ndm->ndm_ifindex;
	memcpy(&key.addr, RTA_DATA(tb[NDA_DST]), 4);
	dbkey.data = &key;
	dbkey.size = sizeof(key);

	if (dbase->get(dbase, &dbkey, &dbdat, 0) != 0) {
		dbdat.data = 0;
		dbdat.size = 0;
	}

	if (n->nlmsg_type == RTM_GETNEIGH) {
		if (!(n->nlmsg_flags&NLM_F_REQUEST))
			return 0;

		if (!(ndm->ndm_state&(NUD_PROBE|NUD_INCOMPLETE))) {
			stats.app_bad++;
			return 0;
		}

		if (ndm->ndm_state&NUD_PROBE) {
			/* If we get this, kernel still has some valid
			 * address, but unicast probing failed and host
			 * is either dead or changed its mac address.
			 * Kernel is going to initiate broadcast resolution.
			 * OK, we invalidate our information as well.
			 */
			if (dbdat.data && !IS_NEG(dbdat.data))
				stats.app_neg++;

			dbase->del(dbase, &dbkey, 0);
		} else {
			/* If we get this kernel does not have any information.
			 * If we have something tell this to kernel. */
			stats.app_recv++;
			if (dbdat.data && !IS_NEG(dbdat.data)) {
				stats.app_success++;
				respond_to_kernel(key.iface, key.addr, dbdat.data, dbdat.size);
				return 0;
			}

			/* Sheeit! We have nothing to tell. */
			/* If we have recent negative entry, be silent. */
			if (dbdat.data && NEG_VALID(dbdat.data)) {
				if (NEG_CNT(dbdat.data) >= active_probing) {
					stats.app_suppressed++;
					return 0;
				}
				do_acct = 1;
			}
		}

		if (active_probing &&
		    queue_active_probe(ndm->ndm_ifindex, key.addr) == 0 &&
		    do_acct) {
			NEG_CNT(dbdat.data)++;
			dbase->put(dbase, &dbkey, &dbdat, 0);
		}
	} else if (n->nlmsg_type == RTM_NEWNEIGH) {
		if (n->nlmsg_flags&NLM_F_REQUEST)
			return 0;

		if (ndm->ndm_state&NUD_FAILED) {
			/* Kernel was not able to resolve. Host is dead.
			 * Create negative entry if it is not present
			 * or renew it if it is too old. */
			if (!dbdat.data ||
			    !IS_NEG(dbdat.data) ||
			    !NEG_VALID(dbdat.data)) {
				__u8 ndata[6];

				stats.kern_neg++;
				prepare_neg_entry(ndata, time(NULL));
				dbdat.data = ndata;
				dbdat.size = sizeof(ndata);
				dbase->put(dbase, &dbkey, &dbdat, 0);
			}
		} else if (tb[NDA_LLADDR]) {
			if (dbdat.data && !IS_NEG(dbdat.data)) {
				if (memcmp(RTA_DATA(tb[NDA_LLADDR]), dbdat.data, dbdat.size) == 0)
					return 0;
				stats.kern_change++;
			} else {
				stats.kern_new++;
			}
			dbdat.data = RTA_DATA(tb[NDA_LLADDR]);
			dbdat.size = RTA_PAYLOAD(tb[NDA_LLADDR]);
			dbase->put(dbase, &dbkey, &dbdat, 0);
		}
	}
	return 0;
}

static void load_initial_table(void)
{
	if (rtnl_wilddump_request(&rth, AF_INET, RTM_GETNEIGH) < 0) {
		perror("dump request failed");
		exit(1);
	}

}

static void get_kern_msg(void)
{
	int status;
	struct nlmsghdr *h;
	struct sockaddr_nl nladdr = {};
	struct iovec iov;
	char   buf[8192];
	struct msghdr msg = {
		(void *)&nladdr, sizeof(nladdr),
		&iov,	1,
		NULL,	0,
		0
	};

	iov.iov_base = buf;
	iov.iov_len = sizeof(buf);

	status = recvmsg(rth.fd, &msg, MSG_DONTWAIT);

	if (status <= 0)
		return;

	if (msg.msg_namelen != sizeof(nladdr))
		return;

	if (nladdr.nl_pid)
		return;

	for (h = (struct nlmsghdr *)buf; status >= sizeof(*h); ) {
		int len = h->nlmsg_len;
		int l = len - sizeof(*h);

		if (l < 0 || len > status)
			return;

		if (do_one_request(h) < 0)
			return;

		status -= NLMSG_ALIGN(len);
		h = (struct nlmsghdr *)((char *)h + NLMSG_ALIGN(len));
	}
}