HardenedBSD/usr.bin/netstat/if.c

/*-
 * SPDX-License-Identifier: BSD-3-Clause
 *
 * Copyright (c) 2013 Gleb Smirnoff <glebius@FreeBSD.org>
 * Copyright (c) 1983, 1988, 1993
 *	The Regents of the University of California.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#if 0
#ifndef lint
static char sccsid[] = "@(#)if.c	8.3 (Berkeley) 4/28/95";
#endif /* not lint */
#endif

#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");

#include <sys/param.h>
#include <sys/protosw.h>
#include <sys/socket.h>
#include <sys/socketvar.h>
#include <sys/time.h>

#include <net/if.h>
#include <net/if_dl.h>
#include <net/if_types.h>
#include <net/ethernet.h>
#include <netinet/in.h>
#include <netinet/in_var.h>
#include <arpa/inet.h>
#ifdef PF
#include <net/pfvar.h>
#include <net/if_pfsync.h>
#endif

#include <err.h>
#include <errno.h>
#include <ifaddrs.h>
#include <libutil.h>
#ifdef INET6
#include <netdb.h>
#endif
#include <signal.h>
#include <stdbool.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sysexits.h>
#include <unistd.h>
#include <libxo/xo.h>

#include "netstat.h"

static void sidewaysintpr(void);

#ifdef PF
static const char* pfsyncacts[] = {
	/* PFSYNC_ACT_CLR */		"clear all request",
	/* PFSYNC_ACT_INS_1301 */	"13.1 state insert",
	/* PFSYNC_ACT_INS_ACK */	"state inserted ack",
	/* PFSYNC_ACT_UPD_1301 */	"13.1 state update",
	/* PFSYNC_ACT_UPD_C */		"compressed state update",
	/* PFSYNC_ACT_UPD_REQ */	"uncompressed state request",
	/* PFSYNC_ACT_DEL */		"state delete",
	/* PFSYNC_ACT_DEL_C */		"compressed state delete",
	/* PFSYNC_ACT_INS_F */		"fragment insert",
	/* PFSYNC_ACT_DEL_F */		"fragment delete",
	/* PFSYNC_ACT_BUS */		"bulk update mark",
	/* PFSYNC_ACT_TDB */		"TDB replay counter update",
	/* PFSYNC_ACT_EOF */		"end of frame mark",
	/* PFSYNC_ACT_INS_1400 */	"state insert",
	/* PFSYNC_ACT_UPD_1400 */	"state update",
};

static const char* pfsyncacts_name[] = {
	/* PFSYNC_ACT_CLR */		"clear-all-request",
	/* PFSYNC_ACT_INS_1301 */	"state-insert-1301",
	/* PFSYNC_ACT_INS_ACK */	"state-inserted-ack",
	/* PFSYNC_ACT_UPD_1301 */	"state-update-1301",
	/* PFSYNC_ACT_UPD_C */		"compressed-state-update",
	/* PFSYNC_ACT_UPD_REQ */	"uncompressed-state-request",
	/* PFSYNC_ACT_DEL */		"state-delete",
	/* PFSYNC_ACT_DEL_C */		"compressed-state-delete",
	/* PFSYNC_ACT_INS_F */		"fragment-insert",
	/* PFSYNC_ACT_DEL_F */		"fragment-delete",
	/* PFSYNC_ACT_BUS */		"bulk-update-mark",
	/* PFSYNC_ACT_TDB */		"TDB-replay-counter-update",
	/* PFSYNC_ACT_EOF */		"end-of-frame-mark",
	/* PFSYNC_ACT_INS_1400 */	"state-insert",
	/* PFSYNC_ACT_UPD_1400 */	"state-update",
};

static void
pfsync_acts_stats(const char *list, const char *desc, uint64_t *a)
{
	int i;

	xo_open_list(list);
	for (i = 0; i < PFSYNC_ACT_MAX; i++, a++) {
		if (*a || sflag <= 1) {
			xo_open_instance(list);
			xo_emit("\t\t{e:name}{:count/%ju} {N:/%s%s %s}\n",
			    pfsyncacts_name[i], (uintmax_t)(*a),
			    pfsyncacts[i], plural(*a), desc);
			xo_close_instance(list);
		}
	}
	xo_close_list(list);
}

/*
 * Dump pfsync statistics structure.
 */
void
pfsync_stats(u_long off, const char *name, int af1 __unused, int proto __unused)
{
	struct pfsyncstats pfsyncstat;

	if (fetch_stats("net.pfsync.stats", off, &pfsyncstat,
	    sizeof(pfsyncstat), kread) != 0)
		return;

	xo_emit("{T:/%s}:\n", name);
	xo_open_container(name);

#define	p(f, m) if (pfsyncstat.f || sflag <= 1) \
	xo_emit(m, (uintmax_t)pfsyncstat.f, plural(pfsyncstat.f))

	p(pfsyncs_ipackets, "\t{:received-inet-packets/%ju} "
	    "{N:/packet%s received (IPv4)}\n");
	p(pfsyncs_ipackets6, "\t{:received-inet6-packets/%ju} "
	    "{N:/packet%s received (IPv6)}\n");
	pfsync_acts_stats("input-histogram", "received",
	    &pfsyncstat.pfsyncs_iacts[0]);
	p(pfsyncs_badif, "\t\t{:dropped-bad-interface/%ju} "
	    "{N:/packet%s discarded for bad interface}\n");
	p(pfsyncs_badttl, "\t\t{:dropped-bad-ttl/%ju} "
	    "{N:/packet%s discarded for bad ttl}\n");
	p(pfsyncs_hdrops, "\t\t{:dropped-short-header/%ju} "
	    "{N:/packet%s shorter than header}\n");
	p(pfsyncs_badver, "\t\t{:dropped-bad-version/%ju} "
	    "{N:/packet%s discarded for bad version}\n");
	p(pfsyncs_badauth, "\t\t{:dropped-bad-auth/%ju} "
	    "{N:/packet%s discarded for bad HMAC}\n");
	p(pfsyncs_badact,"\t\t{:dropped-bad-action/%ju} "
	    "{N:/packet%s discarded for bad action}\n");
	p(pfsyncs_badlen, "\t\t{:dropped-short/%ju} "
	    "{N:/packet%s discarded for short packet}\n");
	p(pfsyncs_badval, "\t\t{:dropped-bad-values/%ju} "
	    "{N:/state%s discarded for bad values}\n");
	p(pfsyncs_stale, "\t\t{:dropped-stale-state/%ju} "
	    "{N:/stale state%s}\n");
	p(pfsyncs_badstate, "\t\t{:dropped-failed-lookup/%ju} "
	    "{N:/failed state lookup\\/insert%s}\n");
	p(pfsyncs_opackets, "\t{:sent-inet-packets/%ju} "
	    "{N:/packet%s sent (IPv4})\n");
	p(pfsyncs_opackets6, "\t{:send-inet6-packets/%ju} "
	    "{N:/packet%s sent (IPv6})\n");
	pfsync_acts_stats("output-histogram", "sent",
	    &pfsyncstat.pfsyncs_oacts[0]);
	p(pfsyncs_onomem, "\t\t{:discarded-no-memory/%ju} "
	    "{N:/failure%s due to mbuf memory error}\n");
	p(pfsyncs_oerrors, "\t\t{:send-errors/%ju} "
	    "{N:/send error%s}\n");
#undef p
	xo_close_container(name);
}
#endif /* PF */

/*
 * Display a formatted value, or a '-' in the same space.
 */
static void
show_stat(const char *fmt, int width, const char *name,
    u_long value, short showvalue, int div1000)
{
	const char *lsep, *rsep;
	char newfmt[64];

	lsep = "";
	if (strncmp(fmt, "LS", 2) == 0) {
		lsep = " ";
		fmt += 2;
	}
	rsep = " ";
	if (strncmp(fmt, "NRS", 3) == 0) {
		rsep = "";
		fmt += 3;
	}
	if (showvalue == 0) {
		/* Print just dash. */
		xo_emit("{P:/%s}{D:/%*s}{P:/%s}", lsep, width, "-", rsep);
		return;
	}

	/*
	 * XXX: workaround {P:} modifier can't be empty and doesn't seem to
	 * take args... so we need to conditionally include it in the format.
	 */
#define maybe_pad(pad)	do {						    \
	if (strlen(pad)) {						    \
		snprintf(newfmt, sizeof(newfmt), "{P:%s}", pad);	    \
		xo_emit(newfmt);					    \
	}								    \
} while (0)

	if (hflag) {
		char buf[5];

		/* Format in human readable form. */
		humanize_number(buf, sizeof(buf), (int64_t)value, "",
		    HN_AUTOSCALE, HN_NOSPACE | HN_DECIMAL | \
		    ((div1000) ? HN_DIVISOR_1000 : 0));
		maybe_pad(lsep);
		snprintf(newfmt, sizeof(newfmt), "{:%s/%%%ds}", name, width);
		xo_emit(newfmt, buf);
		maybe_pad(rsep);
	} else {
		/* Construct the format string. */
		maybe_pad(lsep);
		snprintf(newfmt, sizeof(newfmt), "{:%s/%%%d%s}",
		    name, width, fmt);
		xo_emit(newfmt, value);
		maybe_pad(rsep);
	}
}

/*
 * Find next multiaddr for a given interface name.
 */
static struct ifmaddrs *
next_ifma(struct ifmaddrs *ifma, const char *name, const sa_family_t family)
{

	for(; ifma != NULL; ifma = ifma->ifma_next) {
		struct sockaddr_dl *sdl;

		sdl = (struct sockaddr_dl *)ifma->ifma_name;
		if (ifma->ifma_addr->sa_family == family &&
		    strcmp(sdl->sdl_data, name) == 0)
			break;
	}

	return (ifma);
}

enum process_op { MEASURE, EMIT };

static void
process_ifa_addr(enum process_op op, struct ifaddrs *ifa, int *max_net_len,
    int *max_addr_len, bool *network, bool *link)
{
	int net_len, addr_len;
	const char *nn, *rn;

	if (op == EMIT) {
		net_len = *max_net_len;
		addr_len = *max_addr_len;
	}

	switch (ifa->ifa_addr->sa_family) {
	case AF_UNSPEC:
		if (op == MEASURE) {
			net_len = strlen("none");
			addr_len = strlen("none");
		} else {
			xo_emit("{:network/%-*.*s}  ", net_len, net_len,
			    "none");
			xo_emit("{:address/%-*.*s} ", addr_len, addr_len,
			    "none");
		}
		break;
	case AF_INET:
#ifdef INET6
	case AF_INET6:
#endif /* INET6 */
		nn = netname(ifa->ifa_addr, ifa->ifa_netmask);
		rn = routename(ifa->ifa_addr, numeric_addr);
		if (op == MEASURE) {
			net_len = strlen(nn);
			addr_len = strlen(rn);
		} else {
			xo_emit("{t:network/%-*s}  ", net_len, nn);
			xo_emit("{t:address/%-*s} ", addr_len, rn);
		}

		if (network != NULL)
			*network = true;
		break;
	case AF_LINK:
	    {
		struct sockaddr_dl *sdl;
		char linknum[sizeof("<Link#32767>")];

		sdl = (struct sockaddr_dl *)ifa->ifa_addr;
		snprintf(linknum, sizeof(linknum), "<Link#%d>", sdl->sdl_index);
		if (op == MEASURE) {
			net_len = strlen(linknum);
			if (sdl->sdl_nlen == 0 &&
			    sdl->sdl_alen == 0 &&
			    sdl->sdl_slen == 0)
				addr_len = 1;
			else
				addr_len = strlen(routename(ifa->ifa_addr, 1));
		} else {
			xo_emit("{t:network/%-*.*s}  ", net_len, net_len,
			    linknum);
			if (sdl->sdl_nlen == 0 &&
			    sdl->sdl_alen == 0 &&
			    sdl->sdl_slen == 0)
				xo_emit("{P:/%*s} ", addr_len, "");
			else
				xo_emit("{t:address/%-*.*s} ", addr_len,
				    addr_len, routename(ifa->ifa_addr, 1));
		}
		if (link != NULL)
			*link = true;
		break;
	    }
	}

	if (op == MEASURE) {
		if (net_len > *max_net_len)
			*max_net_len = net_len;
		if (addr_len > *max_addr_len)
			*max_addr_len = addr_len;
	}
}

static int
max_num_len(int max_len, u_long num)
{
	int len = 2;		/* include space */

	for (; num > 10; len++)
		num /= 10;
	return (MAX(max_len, len));
}

/*
 * Print a description of the network interfaces.
 */
void
intpr(void (*pfunc)(char *), int af)
{
	struct ifaddrs *ifap, *ifa;
	struct ifmaddrs *ifmap, *ifma;
	u_int ifn_len_max = 5, ifn_len;
	u_int net_len = strlen("Network "), addr_len = strlen("Address ");
	u_int npkt_len = 8, nbyte_len = 10, nerr_len = 5;

	if (interval)
		return sidewaysintpr();

	if (getifaddrs(&ifap) != 0)
		err(EX_OSERR, "getifaddrs");
	if (aflag && getifmaddrs(&ifmap) != 0)
		err(EX_OSERR, "getifmaddrs");

	for (ifa = ifap; ifa; ifa = ifa->ifa_next) {
		if (interface != NULL &&
		    strcmp(ifa->ifa_name, interface) != 0)
			continue;
		if (af != AF_UNSPEC && ifa->ifa_addr->sa_family != af)
			continue;
		ifn_len = strlen(ifa->ifa_name);
		if ((ifa->ifa_flags & IFF_UP) == 0)
			++ifn_len;
		ifn_len_max = MAX(ifn_len_max, ifn_len);
		process_ifa_addr(MEASURE, ifa, &net_len, &addr_len,
		    NULL, NULL);

#define	IFA_STAT(s)	(((struct if_data *)ifa->ifa_data)->ifi_ ## s)
		if (!hflag) {
			npkt_len = max_num_len(npkt_len, IFA_STAT(ipackets));
			npkt_len = max_num_len(npkt_len, IFA_STAT(opackets));
			nerr_len = max_num_len(nerr_len, IFA_STAT(ierrors));
			nerr_len = max_num_len(nerr_len, IFA_STAT(iqdrops));
			nerr_len = max_num_len(nerr_len, IFA_STAT(collisions));
			if (dflag)
				nerr_len = max_num_len(nerr_len,
				    IFA_STAT(oqdrops));
			if (bflag) {
				nbyte_len = max_num_len(nbyte_len,
				    IFA_STAT(ibytes));
				nbyte_len = max_num_len(nbyte_len,
				    IFA_STAT(obytes));
			}
		}
	}

	xo_open_list("interface");
	if (!pfunc) {
		xo_emit("{T:/%-*.*s}", ifn_len_max, ifn_len_max, "Name");
		xo_emit(" {T:/%5.5s} {T:/%-*.*s}  {T:/%-*.*s} {T:/%*.*s} "
		    "{T:/%*.*s} {T:/%*.*s}",
		    "Mtu", net_len, net_len, "Network", addr_len, addr_len,
		    "Address", npkt_len, npkt_len, "Ipkts",
		    nerr_len, nerr_len, "Ierrs", nerr_len, nerr_len, "Idrop");
		if (bflag)
			xo_emit(" {T:/%*.*s}", nbyte_len, nbyte_len, "Ibytes");
		xo_emit(" {T:/%*.*s} {T:/%*.*s}", npkt_len, npkt_len, "Opkts",
		    nerr_len, nerr_len, "Oerrs");
		if (bflag)
			xo_emit(" {T:/%*.*s}", nbyte_len, nbyte_len, "Obytes");
		xo_emit(" {T:/%*s}", nerr_len, "Coll");
		if (dflag)
			xo_emit(" {T:/%*.*s}", nerr_len, nerr_len, "Drop");
		xo_emit("\n");
	}

	for (ifa = ifap; ifa; ifa = ifa->ifa_next) {
		bool network = false, link = false;
		char *name, *xname, buf[IFNAMSIZ+1];

		if (interface != NULL && strcmp(ifa->ifa_name, interface) != 0)
			continue;

		name = ifa->ifa_name;

		if (pfunc) {

			(*pfunc)(name);

			/*
			 * Skip all ifaddrs belonging to same interface.
			 */
			while(ifa->ifa_next != NULL &&
			    (strcmp(ifa->ifa_next->ifa_name, name) == 0)) {
				ifa = ifa->ifa_next;
			}
			continue;
		}

		if (af != AF_UNSPEC && ifa->ifa_addr->sa_family != af)
			continue;

		xo_open_instance("interface");

		if ((ifa->ifa_flags & IFF_UP) == 0) {
			xname = stpcpy(buf, name);
			*xname++ = '*';
			*xname = '\0';
			xname = buf;
		} else
			xname = name;

		xo_emit("{d:/%-*.*s}{etk:name}{eq:flags/0x%x}",
		    ifn_len_max, ifn_len_max, xname, name, ifa->ifa_flags);

#define IFA_MTU(ifa)	(((struct if_data *)(ifa)->ifa_data)->ifi_mtu)
		show_stat("lu", 6, "mtu", IFA_MTU(ifa), IFA_MTU(ifa), 0);
#undef IFA_MTU

		process_ifa_addr(EMIT, ifa, &net_len, &addr_len,
		    &network, &link);

		show_stat("lu", npkt_len, "received-packets",
		    IFA_STAT(ipackets), link|network, 1);
		show_stat("lu", nerr_len, "received-errors", IFA_STAT(ierrors),
		    link, 1);
		show_stat("lu", nerr_len, "dropped-packets", IFA_STAT(iqdrops),
		    link, 1);
		if (bflag)
			show_stat("lu", nbyte_len, "received-bytes",
			    IFA_STAT(ibytes), link|network, 0);
		show_stat("lu", npkt_len, "sent-packets", IFA_STAT(opackets),
		    link|network, 1);
		show_stat("lu", nerr_len, "send-errors", IFA_STAT(oerrors),
		    link, 1);
		if (bflag)
			show_stat("lu", nbyte_len, "sent-bytes",
			    IFA_STAT(obytes), link|network, 0);
		show_stat("NRSlu", nerr_len, "collisions", IFA_STAT(collisions),
		    link, 1);
		if (dflag)
			show_stat("LSlu", nerr_len, "dropped-packets",
			    IFA_STAT(oqdrops), link, 1);
		xo_emit("\n");

		if (!aflag) {
			xo_close_instance("interface");
			continue;
		}

		/*
		 * Print family's multicast addresses.
		 */
		xo_open_list("multicast-address");
		for (ifma = next_ifma(ifmap, ifa->ifa_name,
		    ifa->ifa_addr->sa_family);
		    ifma != NULL;
		    ifma = next_ifma(ifma, ifa->ifa_name,
		    ifa->ifa_addr->sa_family)) {
			const char *fmt = NULL;

			xo_open_instance("multicast-address");
			switch (ifma->ifma_addr->sa_family) {
			case AF_LINK:
			    {
				struct sockaddr_dl *sdl;

				sdl = (struct sockaddr_dl *)ifma->ifma_addr;
				if (sdl->sdl_type != IFT_ETHER &&
				    sdl->sdl_type != IFT_FDDI)
					break;
			    }
				/* FALLTHROUGH */
			case AF_INET:
#ifdef INET6
			case AF_INET6:
#endif /* INET6 */
				fmt = routename(ifma->ifma_addr, numeric_addr);
				break;
			}
			if (fmt) {
				if (Wflag)
					xo_emit("{P:/%27s }"
					    "{t:address/%-17s/}", "", fmt);
				else
					xo_emit("{P:/%25s }"
					    "{t:address/%-17.17s/}", "", fmt);
				if (ifma->ifma_addr->sa_family == AF_LINK) {
					xo_emit(" {:received-packets/%8lu}",
					    IFA_STAT(imcasts));
					xo_emit("{P:/%*s}", bflag? 17 : 6, "");
					xo_emit(" {:sent-packets/%8lu}",
					    IFA_STAT(omcasts));
 				}
				xo_emit("\n");
			}
			xo_close_instance("multicast-address");
			ifma = ifma->ifma_next;
		}
		xo_close_list("multicast-address");
		xo_close_instance("interface");
	}
	xo_close_list("interface");

	freeifaddrs(ifap);
	if (aflag)
		freeifmaddrs(ifmap);
}

struct iftot {
	u_long	ift_ip;			/* input packets */
	u_long	ift_ie;			/* input errors */
	u_long	ift_id;			/* input drops */
	u_long	ift_op;			/* output packets */
	u_long	ift_oe;			/* output errors */
	u_long	ift_od;			/* output drops */
	u_long	ift_co;			/* collisions */
	u_long	ift_ib;			/* input bytes */
	u_long	ift_ob;			/* output bytes */
};

/*
 * Obtain stats for interface(s).
 */
static void
fill_iftot(struct iftot *st)
{
	struct ifaddrs *ifap, *ifa;
	bool found = false;

	if (getifaddrs(&ifap) != 0)
		xo_err(EX_OSERR, "getifaddrs");

	bzero(st, sizeof(*st));

	for (ifa = ifap; ifa; ifa = ifa->ifa_next) {
		if (ifa->ifa_addr->sa_family != AF_LINK)
			continue;
		if (interface) {
			if (strcmp(ifa->ifa_name, interface) == 0)
				found = true;
			else
				continue;
		}

		st->ift_ip += IFA_STAT(ipackets);
		st->ift_ie += IFA_STAT(ierrors);
		st->ift_id += IFA_STAT(iqdrops);
		st->ift_ib += IFA_STAT(ibytes);
		st->ift_op += IFA_STAT(opackets);
		st->ift_oe += IFA_STAT(oerrors);
		st->ift_od += IFA_STAT(oqdrops);
		st->ift_ob += IFA_STAT(obytes);
 		st->ift_co += IFA_STAT(collisions);
	}

	if (interface && found == false)
		xo_err(EX_DATAERR, "interface %s not found", interface);

	freeifaddrs(ifap);
}

/*
 * Set a flag to indicate that a signal from the periodic itimer has been
 * caught.
 */
static sig_atomic_t signalled;
static void
catchalarm(int signo __unused)
{
	signalled = true;
}

/*
 * Print a running summary of interface statistics.
 * Repeat display every interval seconds, showing statistics
 * collected over that interval.  Assumes that interval is non-zero.
 * First line printed at top of screen is always cumulative.
 */
static void
sidewaysintpr(void)
{
	struct iftot ift[2], *new, *old;
	struct itimerval interval_it;
	int oldmask, line;

	new = &ift[0];
	old = &ift[1];
	fill_iftot(old);

	(void)signal(SIGALRM, catchalarm);
	signalled = false;
	interval_it.it_interval.tv_sec = interval;
	interval_it.it_interval.tv_usec = 0;
	interval_it.it_value = interval_it.it_interval;
	setitimer(ITIMER_REAL, &interval_it, NULL);
	xo_open_list("interface-statistics");

banner:
	xo_emit("{T:/%17s} {T:/%14s} {T:/%16s}\n", "input",
	    interface != NULL ? interface : "(Total)", "output");
	xo_emit("{T:/%10s} {T:/%5s} {T:/%5s} {T:/%10s} {T:/%10s} {T:/%5s} "
	    "{T:/%10s} {T:/%5s}",
	    "packets", "errs", "idrops", "bytes", "packets", "errs", "bytes",
	    "colls");
	if (dflag)
		xo_emit(" {T:/%5.5s}", "drops");
	xo_emit("\n");
	xo_flush();
	line = 0;

loop:
	if ((noutputs != 0) && (--noutputs == 0)) {
		xo_close_list("interface-statistics");
		return;
	}
	oldmask = sigblock(sigmask(SIGALRM));
	while (!signalled)
		sigpause(0);
	signalled = false;
	sigsetmask(oldmask);
	line++;

	fill_iftot(new);

	xo_open_instance("stats");
	show_stat("lu", 10, "received-packets",
	    new->ift_ip - old->ift_ip, 1, 1);
	show_stat("lu", 5, "received-errors",
	    new->ift_ie - old->ift_ie, 1, 1);
	show_stat("lu", 5, "dropped-packets",
	    new->ift_id - old->ift_id, 1, 1);
	show_stat("lu", 10, "received-bytes",
	    new->ift_ib - old->ift_ib, 1, 0);
	show_stat("lu", 10, "sent-packets",
	    new->ift_op - old->ift_op, 1, 1);
	show_stat("lu", 5, "send-errors",
	    new->ift_oe - old->ift_oe, 1, 1);
	show_stat("lu", 10, "sent-bytes",
	    new->ift_ob - old->ift_ob, 1, 0);
	show_stat("NRSlu", 5, "collisions",
	    new->ift_co - old->ift_co, 1, 1);
	if (dflag)
		show_stat("LSlu", 5, "dropped-packets",
		    new->ift_od - old->ift_od, 1, 1);
	xo_close_instance("stats");
	xo_emit("\n");
	xo_flush();

	if (new == &ift[0]) {
		new = &ift[1];
		old = &ift[0];
	} else {
		new = &ift[0];
		old = &ift[1];
	}

	if (line == 21)
		goto banner;
	else
		goto loop;

	/* NOTREACHED */
}