/*-
 * SPDX-License-Identifier: BSD-3-Clause
 *
 * 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 "defs.h"
#include "pathnames.h"
#include <signal.h>
#include <fcntl.h>
#include <sys/file.h>

pid_t   mypid;

naddr   myaddr;                         /* system address */
static char myname[MAXHOSTNAMELEN+1];

static int verbose;

int     supplier;                       /* supply or broadcast updates */
int     supplier_set;
static int ipforwarding = 1;            /* kernel forwarding on */

static int default_gateway;             /* 1=advertise default */
static int background = 1;
int     ridhosts;                       /* 1=reduce host routes */
int     mhome;                          /* 1=want multi-homed host route */
int     advertise_mhome;                /* 1=must continue advertising it */
int     auth_ok = 1;                    /* 1=ignore auth if we do not care */
int     insecure;                       /* Reply to special queries or not */

struct timeval epoch;                   /* when started */
struct timeval clk;
static struct timeval prev_clk;
static int usec_fudge;
struct timeval now;                     /* current idea of time */
time_t  now_stale;
time_t  now_expire;
time_t  now_garbage;

static struct timeval next_bcast;       /* next general broadcast */
struct timeval no_flash = {             /* inhibit flash update */
        EPOCH+SUPPLY_INTERVAL, 0
};

static struct timeval flush_kern_timer;

static fd_set fdbits;
static int sock_max;
int     rip_sock = -1;                  /* RIP socket */
const struct interface *rip_sock_mcast; /* current multicast interface */
int     rt_sock;                        /* routing socket */
int     rt_sock_seqno;


static  int get_rip_sock(naddr, int);
static void timevalsub(struct timeval *, struct timeval *, struct timeval *);
static void sigalrm(int s UNUSED);
static void sigterm(int sig);

int
main(int argc,
     char *argv[])
{
        int n, mib[4], off;
        size_t len;
        char *p, *q;
        const char *cp;
        struct timeval wtime, t2;
        time_t dt;
        fd_set ibits;
        naddr p_net, p_mask;
        struct interface *ifp;
        struct parm parm;
        char *tracename = 0;


        /* Some shells are badly broken and send SIGHUP to backgrounded
         * processes.
         */
        signal(SIGHUP, SIG_IGN);

        openlog("routed", LOG_PID, LOG_DAEMON);
        ftrace = stdout;

        gettimeofday(&clk, 0);
        prev_clk = clk;
        epoch = clk;
        epoch.tv_sec -= EPOCH;
        now.tv_sec = EPOCH;
        now_stale = EPOCH - STALE_TIME;
        now_expire = EPOCH - EXPIRE_TIME;
        now_garbage = EPOCH - GARBAGE_TIME;
        wtime.tv_sec = 0;

        (void)gethostname(myname, sizeof(myname)-1);
        (void)gethost(myname, &myaddr);

        while ((n = getopt(argc, argv, "isqdghmAtvT:F:P:")) != -1) {
                switch (n) {
                case 'i':
                        insecure++;
                        break;
                case 's':
                        supplier = 1;
                        supplier_set = 1;
                        break;

                case 'q':
                        supplier = 0;
                        supplier_set = 1;
                        break;

                case 'd':
                        background = 0;
                        break;

                case 'g':
                        memset(&parm, 0, sizeof(parm));
                        parm.parm_d_metric = 1;
                        cp = check_parms(&parm);
                        if (cp != 0)
                                msglog("bad -g: %s", cp);
                        else
                                default_gateway = 1;
                        break;

                case 'h':               /* suppress extra host routes */
                        ridhosts = 1;
                        break;

                case 'm':               /* advertise host route */
                        mhome = 1;      /* on multi-homed hosts */
                        break;

                case 'A':
                        /* Ignore authentication if we do not care.
                         * Crazy as it is, that is what RFC 1723 requires.
                         */
                        auth_ok = 0;
                        break;

                case 't':
                        new_tracelevel++;
                        break;

                case 'T':
                        tracename = optarg;
                        break;

                case 'F':               /* minimal routes for SLIP */
                        n = FAKE_METRIC;
                        p = strchr(optarg,',');
                        if (p && *p != '\0') {
                                n = (int)strtoul(p+1, &q, 0);
                                if (*q == '\0'
                                    && n <= HOPCNT_INFINITY-1
                                    && n >= 1)
                                        *p = '\0';
                        }
                        if (!getnet(optarg, &p_net, &p_mask)) {
                                msglog("bad network; \"-F %s\"",
                                       optarg);
                                break;
                        }
                        memset(&parm, 0, sizeof(parm));
                        parm.parm_net = p_net;
                        parm.parm_mask = p_mask;
                        parm.parm_d_metric = n;
                        cp = check_parms(&parm);
                        if (cp != 0)
                                msglog("bad -F: %s", cp);
                        break;

                case 'P':
                        /* handle arbitrary parameters.
                         */
                        q = strdup(optarg);
                        cp = parse_parms(q, 0);
                        if (cp != 0)
                                msglog("%s in \"-P %s\"", cp, optarg);
                        free(q);
                        break;

                case 'v':
                        /* display version */
                        verbose++;
                        msglog("version 2.31");
                        break;

                default:
                        goto usage;
                }
        }
        argc -= optind;
        argv += optind;

        if (tracename == 0 && argc >= 1) {
                tracename = *argv++;
                argc--;
        }
        if (tracename != 0 && tracename[0] == '\0')
                goto usage;
        if (argc != 0) {
usage:
                logbad(0, "usage: routed [-sqdghmAtv] [-T tracefile]"
                       " [-F net[,metric]] [-P parms]");
        }
        if (geteuid() != 0) {
                if (verbose)
                        exit(0);
                logbad(0, "requires UID 0");
        }

        mib[0] = CTL_NET;
        mib[1] = PF_INET;
        mib[2] = IPPROTO_IP;
        mib[3] = IPCTL_FORWARDING;
        len = sizeof(ipforwarding);
        if (sysctl(mib, 4, &ipforwarding, &len, 0, 0) < 0)
                LOGERR("sysctl(IPCTL_FORWARDING)");

        if (!ipforwarding) {
                if (supplier)
                        msglog("-s incompatible with ipforwarding=0");
                if (default_gateway) {
                        msglog("-g incompatible with ipforwarding=0");
                        default_gateway = 0;
                }
                supplier = 0;
                supplier_set = 1;
        }
        if (default_gateway) {
                if (supplier_set && !supplier) {
                        msglog("-g and -q incompatible");
                } else {
                        supplier = 1;
                        supplier_set = 1;
                }
        }


        signal(SIGALRM, sigalrm);
        if (!background)
                signal(SIGHUP, sigterm);    /* SIGHUP fatal during debugging */
        signal(SIGTERM, sigterm);
        signal(SIGINT, sigterm);
        signal(SIGUSR1, sigtrace_on);
        signal(SIGUSR2, sigtrace_off);

        /* get into the background */
        if (background && daemon(0, 1) < 0)
                BADERR(0,"daemon()");

        mypid = getpid();

        /* prepare socket connected to the kernel.
         */
        rt_sock = socket(AF_ROUTE, SOCK_RAW, 0);
        if (rt_sock < 0)
                BADERR(1,"rt_sock = socket()");
        if (fcntl(rt_sock, F_SETFL, O_NONBLOCK) == -1)
                logbad(1, "fcntl(rt_sock) O_NONBLOCK: %s", strerror(errno));
        off = 0;
        if (setsockopt(rt_sock, SOL_SOCKET,SO_USELOOPBACK,
                       &off,sizeof(off)) < 0)
                LOGERR("setsockopt(SO_USELOOPBACK,0)");

        fix_select();


        if (tracename != 0) {
                strncpy(inittracename, tracename, sizeof(inittracename)-1);
                set_tracefile(inittracename, "%s", -1);
        } else {
                tracelevel_msg("%s", -1);   /* turn on tracing to stdio */
        }

        bufinit();

        /* initialize radix tree */
        rtinit();

        /* Pick a random part of the second for our output to minimize
         * collisions.
         *
         * Start broadcasting after hearing from other routers, and
         * at a random time so a bunch of systems do not get synchronized
         * after a power failure.
         */
        intvl_random(&next_bcast, EPOCH+MIN_WAITTIME, EPOCH+SUPPLY_INTERVAL);
        age_timer.tv_usec = next_bcast.tv_usec;
        age_timer.tv_sec = EPOCH+MIN_WAITTIME;
        rdisc_timer = next_bcast;
        ifinit_timer.tv_usec = next_bcast.tv_usec;

        /* Collect an initial view of the world by checking the interface
         * configuration and the kludge file.
         */
        gwkludge();
        ifinit();

        /* Ask for routes */
        rip_query();
        rdisc_sol();

        /* Now turn off stdio if not tracing */
        if (new_tracelevel == 0)
                trace_close(background);

        /* Loop forever, listening and broadcasting.
         */
        for (;;) {
                prev_clk = clk;
                gettimeofday(&clk, 0);
                if (prev_clk.tv_sec == clk.tv_sec
                    && prev_clk.tv_usec == clk.tv_usec+usec_fudge) {
                        /* Much of `routed` depends on time always advancing.
                         * On systems that do not guarantee that gettimeofday()
                         * produces unique timestamps even if called within
                         * a single tick, use trickery like that in classic
                         * BSD kernels.
                         */
                        clk.tv_usec += ++usec_fudge;

                } else {
                        usec_fudge = 0;

                        timevalsub(&t2, &clk, &prev_clk);
                        if (t2.tv_sec < 0
                            || t2.tv_sec > wtime.tv_sec + 5) {
                                /* Deal with time changes before other
                                 * housekeeping to keep everything straight.
                                 */
                                dt = t2.tv_sec;
                                if (dt > 0)
                                        dt -= wtime.tv_sec;
                                trace_act("time changed by %d sec", (int)dt);
                                epoch.tv_sec += dt;
                        }
                }
                timevalsub(&now, &clk, &epoch);
                now_stale = now.tv_sec - STALE_TIME;
                now_expire = now.tv_sec - EXPIRE_TIME;
                now_garbage = now.tv_sec - GARBAGE_TIME;

                /* deal with signals that should affect tracing */
                set_tracelevel();

                if (stopint != 0) {
                        rip_bcast(0);
                        rdisc_adv();
                        trace_off("exiting with signal %d", stopint);
                        exit(stopint | 128);
                }

                /* look for new or dead interfaces */
                timevalsub(&wtime, &ifinit_timer, &now);
                if (wtime.tv_sec <= 0) {
                        wtime.tv_sec = 0;
                        ifinit();
                        rip_query();
                        continue;
                }

                /* Check the kernel table occasionally for mysteriously
                 * evaporated routes
                 */
                timevalsub(&t2, &flush_kern_timer, &now);
                if (t2.tv_sec <= 0) {
                        flush_kern();
                        flush_kern_timer.tv_sec = (now.tv_sec
                                                   + CHECK_QUIET_INTERVAL);
                        continue;
                }
                if (timercmp(&t2, &wtime, <))
                        wtime = t2;

                /* If it is time, then broadcast our routes.
                 */
                if (supplier || advertise_mhome) {
                        timevalsub(&t2, &next_bcast, &now);
                        if (t2.tv_sec <= 0) {
                                /* Synchronize the aging and broadcast
                                 * timers to minimize awakenings
                                 */
                                age(0);

                                rip_bcast(0);

                                /* It is desirable to send routing updates
                                 * regularly.  So schedule the next update
                                 * 30 seconds after the previous one was
                                 * scheduled, instead of 30 seconds after
                                 * the previous update was finished.
                                 * Even if we just started after discovering
                                 * a 2nd interface or were otherwise delayed,
                                 * pick a 30-second anniversary of the
                                 * original broadcast time.
                                 */
                                n = 1 + (0-t2.tv_sec)/SUPPLY_INTERVAL;
                                next_bcast.tv_sec += n*SUPPLY_INTERVAL;

                                continue;
                        }

                        if (timercmp(&t2, &wtime, <))
                                wtime = t2;
                }

                /* If we need a flash update, either do it now or
                 * set the delay to end when it is time.
                 *
                 * If we are within MIN_WAITTIME seconds of a full update,
                 * do not bother.
                 */
                if (need_flash
                    && supplier
                    && no_flash.tv_sec+MIN_WAITTIME < next_bcast.tv_sec) {
                        /* accurate to the millisecond */
                        if (!timercmp(&no_flash, &now, >))
                                rip_bcast(1);
                        timevalsub(&t2, &no_flash, &now);
                        if (timercmp(&t2, &wtime, <))
                                wtime = t2;
                }

                /* trigger the main aging timer.
                 */
                timevalsub(&t2, &age_timer, &now);
                if (t2.tv_sec <= 0) {
                        age(0);
                        continue;
                }
                if (timercmp(&t2, &wtime, <))
                        wtime = t2;

                /* update the kernel routing table
                 */
                timevalsub(&t2, &need_kern, &now);
                if (t2.tv_sec <= 0) {
                        age(0);
                        continue;
                }
                if (timercmp(&t2, &wtime, <))
                        wtime = t2;

                /* take care of router discovery,
                 * but do it in the correct the millisecond
                 */
                if (!timercmp(&rdisc_timer, &now, >)) {
                        rdisc_age(0);
                        continue;
                }
                timevalsub(&t2, &rdisc_timer, &now);
                if (timercmp(&t2, &wtime, <))
                        wtime = t2;


                /* wait for input or a timer to expire.
                 */
                trace_flush();
                ibits = fdbits;
                n = select(sock_max, &ibits, 0, 0, &wtime);
                if (n <= 0) {
                        if (n < 0 && errno != EINTR && errno != EAGAIN)
                                BADERR(1,"select");
                        continue;
                }

                if (FD_ISSET(rt_sock, &ibits)) {
                        read_rt();
                        n--;
                }
                if (rdisc_sock >= 0 && FD_ISSET(rdisc_sock, &ibits)) {
                        read_d();
                        n--;
                }
                if (rip_sock >= 0 && FD_ISSET(rip_sock, &ibits)) {
                        read_rip(rip_sock, 0);
                        n--;
                }

                LIST_FOREACH(ifp, &ifnet, int_list) {
                        if (n <= 0)
                                break;
                        if (ifp->int_rip_sock >= 0
                            && FD_ISSET(ifp->int_rip_sock, &ibits)) {
                                read_rip(ifp->int_rip_sock, ifp);
                                n--;
                        }
                }
        }
}


/* ARGSUSED */
static void
sigalrm(int s UNUSED)
{
        /* Historically, SIGALRM would cause the daemon to check for
         * new and broken interfaces.
         */
        ifinit_timer.tv_sec = now.tv_sec;
        trace_act("SIGALRM");
}


/* watch for fatal signals */
static void
sigterm(int sig)
{
        stopint = sig;
        (void)signal(sig, SIG_DFL);     /* catch it only once */
}


void
fix_select(void)
{
        struct interface *ifp;


        FD_ZERO(&fdbits);
        sock_max = 0;

        FD_SET(rt_sock, &fdbits);
        if (sock_max <= rt_sock)
                sock_max = rt_sock+1;
        if (rip_sock >= 0) {
                FD_SET(rip_sock, &fdbits);
                if (sock_max <= rip_sock)
                        sock_max = rip_sock+1;
        }
        LIST_FOREACH(ifp, &ifnet, int_list) {
                if (ifp->int_rip_sock >= 0) {
                        FD_SET(ifp->int_rip_sock, &fdbits);
                        if (sock_max <= ifp->int_rip_sock)
                                sock_max = ifp->int_rip_sock+1;
                }
        }
        if (rdisc_sock >= 0) {
                FD_SET(rdisc_sock, &fdbits);
                if (sock_max <= rdisc_sock)
                        sock_max = rdisc_sock+1;
        }
}


void
fix_sock(int sock,
         const char *name)
{
        int on;
#define MIN_SOCKBUF (4*1024)
        static int rbuf;

        if (fcntl(sock, F_SETFL, O_NONBLOCK) == -1)
                logbad(1, "fcntl(%s) O_NONBLOCK: %s",
                       name, strerror(errno));
        on = 1;
        if (setsockopt(sock, SOL_SOCKET,SO_BROADCAST, &on,sizeof(on)) < 0)
                msglog("setsockopt(%s,SO_BROADCAST): %s",
                       name, strerror(errno));
#ifdef USE_PASSIFNAME
        on = 1;
        if (setsockopt(sock, SOL_SOCKET, SO_PASSIFNAME, &on,sizeof(on)) < 0)
                msglog("setsockopt(%s,SO_PASSIFNAME): %s",
                       name, strerror(errno));
#endif

        if (rbuf >= MIN_SOCKBUF) {
                if (setsockopt(sock, SOL_SOCKET, SO_RCVBUF,
                               &rbuf, sizeof(rbuf)) < 0)
                        msglog("setsockopt(%s,SO_RCVBUF=%d): %s",
                               name, rbuf, strerror(errno));
        } else {
                for (rbuf = 60*1024; ; rbuf -= 4096) {
                        if (setsockopt(sock, SOL_SOCKET, SO_RCVBUF,
                                       &rbuf, sizeof(rbuf)) == 0) {
                                trace_act("RCVBUF=%d", rbuf);
                                break;
                        }
                        if (rbuf < MIN_SOCKBUF) {
                                msglog("setsockopt(%s,SO_RCVBUF = %d): %s",
                                       name, rbuf, strerror(errno));
                                break;
                        }
                }
        }
}


/* get a rip socket
 */
static int                              /* <0 or file descriptor */
get_rip_sock(naddr addr,
             int serious)               /* 1=failure to bind is serious */
{
        struct sockaddr_in rsin;
        unsigned char ttl;
        int s;


        if ((s = socket(AF_INET, SOCK_DGRAM, 0)) < 0)
                BADERR(1,"rip_sock = socket()");

        memset(&rsin, 0, sizeof(rsin));
#ifdef _HAVE_SIN_LEN
        rsin.sin_len = sizeof(rsin);
#endif
        rsin.sin_family = AF_INET;
        rsin.sin_port = htons(RIP_PORT);
        rsin.sin_addr.s_addr = addr;
        if (bind(s, (struct sockaddr *)&rsin, sizeof(rsin)) < 0) {
                if (serious)
                        BADERR(errno != EADDRINUSE, "bind(rip_sock)");
                close(s);
                return -1;
        }
        fix_sock(s,"rip_sock");

        ttl = 1;
        if (setsockopt(s, IPPROTO_IP, IP_MULTICAST_TTL,
                       &ttl, sizeof(ttl)) < 0)
                DBGERR(1,"rip_sock setsockopt(IP_MULTICAST_TTL)");

        return s;
}


/* turn off main RIP socket */
void
rip_off(void)
{
        struct interface *ifp;
        naddr addr;


        if (rip_sock >= 0 && !mhome) {
                trace_act("turn off RIP");

                (void)close(rip_sock);
                rip_sock = -1;

                /* get non-broadcast sockets to listen to queries.
                 */
                LIST_FOREACH(ifp, &ifnet, int_list) {
                        if (ifp->int_state & IS_REMOTE)
                                continue;
                        if (ifp->int_rip_sock < 0) {
                                addr = ((ifp->int_if_flags & IFF_POINTOPOINT)
                                        ? ifp->int_dstaddr
                                        : ifp->int_addr);
                                ifp->int_rip_sock = get_rip_sock(addr, 0);
                        }
                }

                fix_select();

                age(0);
        }
}


/* turn on RIP multicast input via an interface
 */
static void
rip_mcast_on(struct interface *ifp)
{
        struct group_req gr;
        struct sockaddr_in *sin;

        if (!IS_RIP_IN_OFF(ifp->int_state)
            && (ifp->int_if_flags & IFF_MULTICAST)
            && !(ifp->int_state & IS_ALIAS)) {
                memset(&gr, 0, sizeof(gr));
                gr.gr_interface = ifp->int_index;
                sin = (struct sockaddr_in *)&gr.gr_group;
                sin->sin_family = AF_INET;
#ifdef _HAVE_SIN_LEN
                sin->sin_len = sizeof(struct sockaddr_in);
#endif
                sin->sin_addr.s_addr = htonl(INADDR_RIP_GROUP);
                if (setsockopt(rip_sock, IPPROTO_IP, MCAST_JOIN_GROUP,
                               &gr, sizeof(gr)) < 0)
                        LOGERR("setsockopt(MCAST_JOIN_GROUP RIP)");
        }
}


/* Prepare socket used for RIP.
 */
void
rip_on(struct interface *ifp)
{
        /* If the main RIP socket is already alive, only start receiving
         * multicasts for this interface.
         */
        if (rip_sock >= 0) {
                if (ifp != NULL)
                        rip_mcast_on(ifp);
                return;
        }

        /* If the main RIP socket is off and it makes sense to turn it on,
         * then turn it on for all of the interfaces.
         * It makes sense if either router discovery is off, or if
         * router discover is on and at most one interface is doing RIP.
         */
        if (rip_interfaces > 0 && (!rdisc_ok || rip_interfaces > 1)) {
                trace_act("turn on RIP");

                /* Close all of the query sockets so that we can open
                 * the main socket.  SO_REUSEPORT is not a solution,
                 * since that would let two daemons bind to the broadcast
                 * socket.
                 */
                LIST_FOREACH(ifp, &ifnet, int_list) {
                        if (ifp->int_rip_sock >= 0) {
                                (void)close(ifp->int_rip_sock);
                                ifp->int_rip_sock = -1;
                        }
                }

                rip_sock = get_rip_sock(INADDR_ANY, 1);
                rip_sock_mcast = NULL;

                /* Do not advertise anything until we have heard something
                 */
                if (next_bcast.tv_sec < now.tv_sec+MIN_WAITTIME)
                        next_bcast.tv_sec = now.tv_sec+MIN_WAITTIME;

                LIST_FOREACH(ifp, &ifnet, int_list) {
                        ifp->int_query_time = NEVER;
                        rip_mcast_on(ifp);
                }
                ifinit_timer.tv_sec = now.tv_sec;

        } else if (ifp != NULL
                   && !(ifp->int_state & IS_REMOTE)
                   && ifp->int_rip_sock < 0) {
                /* RIP is off, so ensure there are sockets on which
                 * to listen for queries.
                 */
                ifp->int_rip_sock = get_rip_sock(ifp->int_addr, 0);
        }

        fix_select();
}


/* die if malloc(3) fails
 */
void *
rtmalloc(size_t size,
         const char *msg)
{
        void *p = malloc(size);
        if (p == NULL)
                logbad(1,"malloc(%lu) failed in %s", (u_long)size, msg);
        return p;
}


/* get a random instant in an interval
 */
void
intvl_random(struct timeval *tp,        /* put value here */
             u_long lo,                 /* value is after this second */
             u_long hi)                 /* and before this */
{
        tp->tv_sec = (time_t)(hi == lo
                              ? lo
                              : (lo + arc4random_uniform(1 + hi - lo)));
        tp->tv_usec = arc4random_uniform(1000000);
}


void
timevaladd(struct timeval *t1,
           struct timeval *t2)
{

        t1->tv_sec += t2->tv_sec;
        if ((t1->tv_usec += t2->tv_usec) >= 1000000) {
                t1->tv_sec++;
                t1->tv_usec -= 1000000;
        }
}


/* t1 = t2 - t3
 */
static void
timevalsub(struct timeval *t1,
           struct timeval *t2,
           struct timeval *t3)
{
        t1->tv_sec = t2->tv_sec - t3->tv_sec;
        if ((t1->tv_usec = t2->tv_usec - t3->tv_usec) < 0) {
                t1->tv_sec--;
                t1->tv_usec += 1000000;
        }
}


/* put a message into the system log
 */
void
msglog(const char *p, ...)
{
        va_list args;

        trace_flush();

        va_start(args, p);
        vsyslog(LOG_ERR, p, args);
        va_end(args);
        if (ftrace != NULL) {
                if (ftrace == stdout)
                        (void)fputs("routed: ", ftrace);
                va_start(args, p);
                (void)vfprintf(ftrace, p, args);
                va_end(args);
                (void)fputc('\n', ftrace);
        }
}


/* Put a message about a bad system into the system log if
 * we have not complained about it recently.
 *
 * It is desirable to complain about all bad systems, but not too often.
 * In the worst case, it is not practical to keep track of all bad systems.
 * For example, there can be many systems with the wrong password.
 */
void
msglim(struct msg_limit *lim, naddr addr, const char *p, ...)
{
        va_list args;
        int i;
        struct msg_sub *ms1, *ms;
        const char *p1;

        /* look for the oldest slot in the table
         * or the slot for the bad router.
         */
        ms = ms1 = lim->subs;
        for (i = MSG_SUBJECT_N; ; i--, ms1++) {
                if (i == 0) {
                        /* Reuse a slot at most once every 10 minutes.
                         */
                        if (lim->reuse > now.tv_sec) {
                                ms = NULL;
                        } else {
                                ms = ms1;
                                lim->reuse = now.tv_sec + 10*60;
                        }
                        break;
                }
                if (ms->addr == addr) {
                        /* Repeat a complaint about a given system at
                         * most once an hour.
                         */
                        if (ms->until > now.tv_sec)
                                ms = NULL;
                        break;
                }
                if (ms->until < ms1->until)
                        ms = ms1;
        }
        if (ms != NULL) {
                ms->addr = addr;
                ms->until = now.tv_sec + 60*60; /* 60 minutes */

                trace_flush();
                for (p1 = p; *p1 == ' '; p1++)
                        continue;
                va_start(args, p);
                vsyslog(LOG_ERR, p1, args);
                va_end(args);
        }

        /* always display the message if tracing */
        if (ftrace != NULL) {
                va_start(args, p);
                (void)vfprintf(ftrace, p, args);
                va_end(args);
                (void)fputc('\n', ftrace);
        }
}


void
logbad(int dump, const char *p, ...)
{
        va_list args;

        trace_flush();

        va_start(args, p);
        vsyslog(LOG_ERR, p, args);
        va_end(args);
        (void)fputs("routed: ", stderr);
        va_start(args, p);
        (void)vfprintf(stderr, p, args);
        va_end(args);
        (void)fputs("; giving up\n",stderr);
        (void)fflush(stderr);

        if (dump)
                abort();
        exit(1);
}