/*-
 * 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.
 */

#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/pflow.h>
#include <net/if_pfsync.h>
#endif

#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 */       "14.0 state insert",
        /* PFSYNC_ACT_UPD_1400 */       "14.0 state update",
        /* PFSYNC_ACT_INS_1500 */       "state insert",
        /* PFSYNC_ACT_UPD_1500 */       "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-1400",
        /* PFSYNC_ACT_UPD_1400 */       "state-update-1400",
        /* PFSYNC_ACT_INS_1500 */       "state-insert",
        /* PFSYNC_ACT_UPD_1500 */       "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);
}

void
pflow_stats(u_long off, const char *name, int af1 __unused, int proto __unused)
{
        struct pflowstats pflowstat;

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

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

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

        p(pflow_flows, "\t{:flows/%ju} {N:/flow%s sent}\n");
        p(pflow_packets, "\t{:packets/%ju} {N:/packet%s sent}\n");
        p(pflow_onomem, "\t{:nomem/%ju} "
            "{N:/send failed due to mbuf memory error}\n");
        p(pflow_oerrors, "\t{:send-error/%ju} {N:/send error}\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 &&
                    sdl->sdl_nlen == strlen(name) &&
                    strncmp(sdl->sdl_data, name, sdl->sdl_nlen) == 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)
                xo_err(EX_OSERR, "getifaddrs");
        if (aflag && getifmaddrs(&ifmap) != 0)
                xo_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;
}

static void
running_stats_banner(void)
{
        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();
}

/*
 * 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");

        /*
         * We print the first banner right away, even if we'll have to wait for
         * the specified interval to get the first statistics line.  Next
         * banners will be printed only when the next statistics line is
         * available.
         */
        running_stats_banner();
        /* Number of written statistics line since latest banner. */
        line = 0;

        for (;;) {
                /* Wait for next interval. */
                oldmask = sigblock(sigmask(SIGALRM));
                while (!signalled)
                        sigpause(0);
                signalled = false;
                sigsetmask(oldmask);

                fill_iftot(new);

                /*
                 * We want that, on a 24-line display, when the previous banner
                 * reaches exactly the top of the screen, a new banner is
                 * printed before the next statistics line.  This ensures that
                 * at least one banner is visible on screen at all time
                 * (provided the screen has at least 24 lines).  Since the
                 * banner takes 2 lines, and the last screen line is occupied by
                 * the cursor, it's after having written 21 statistics lines
                 * that we must output the banner.
                 */
                if (line == 21) {
                        running_stats_banner();
                        line = 0;
                }
                ++line;

                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 ((noutputs != 0) && (--noutputs == 0)) {
                        xo_close_list("interface-statistics");
                        return;
                }

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

        /* NOTREACHED */
}