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Sourcecode: freebsd-utils version File versions

main.c

/*
 * main.c - Point-to-Point Protocol main module
 *
 * Copyright (c) 1989 Carnegie Mellon University.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms are permitted
 * provided that the above copyright notice and this paragraph are
 * duplicated in all such forms and that any documentation,
 * advertising materials, and other materials related to such
 * distribution and use acknowledge that the software was developed
 * by Carnegie Mellon University.  The name of the
 * University may not be used to endorse or promote products derived
 * from this software without specific prior written permission.
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
 * WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
 */

#ifndef lint
static char rcsid[] = "$FreeBSD: src/usr.sbin/pppd/main.c,v 1.22.6.1 2008/11/25 02:59:29 kensmith Exp $";
#endif

#include <stdio.h>
#include <ctype.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <signal.h>
#include <errno.h>
#include <fcntl.h>
#include <syslog.h>
#include <netdb.h>
#include <utmp.h>
#include <pwd.h>
#include <sys/param.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <sys/time.h>
#include <sys/resource.h>
#include <sys/stat.h>
#include <sys/socket.h>

#include "pppd.h"
#include "magic.h"
#include "fsm.h"
#include "lcp.h"
#include "ipcp.h"
#ifdef INET6
#include "ipv6cp.h"
#endif
#include "upap.h"
#include "chap.h"
#include "ccp.h"
#include "pathnames.h"
#include "patchlevel.h"

#ifdef CBCP_SUPPORT
#include "cbcp.h"
#endif

#if defined(SUNOS4)
extern char *strerror();
#endif

#ifdef IPX_CHANGE
#include "ipxcp.h"
#endif /* IPX_CHANGE */
#ifdef AT_CHANGE
#include "atcp.h"
#endif

/* interface vars */
char ifname[32];        /* Interface name */
int ifunit;             /* Interface unit number */

char *progname;               /* Name of this program */
char hostname[MAXNAMELEN];    /* Our hostname */
static char pidfilename[MAXPATHLEN];      /* name of pid file */
static char iffilename[MAXPATHLEN]; /* name of if file */
static char default_devnam[MAXPATHLEN];   /* name of default device */
static pid_t pid;       /* Our pid */
static uid_t uid;       /* Our real user-id */
time_t            etime,stime;      /* End and Start time */
int         minutes;    /* connection duration */
static int conn_running;      /* we have a [dis]connector running */

int ttyfd = -1;               /* Serial port file descriptor */
mode_t tty_mode = -1;         /* Original access permissions to tty */
int baud_rate;                /* Actual bits/second for serial device */
int hungup;             /* terminal has been hung up */
int privileged;               /* we're running as real uid root */
int need_holdoff;       /* need holdoff period before restarting */
int detached;                 /* have detached from terminal */

int phase;              /* where the link is at */
int kill_link;
int open_ccp_flag;

char **script_env;            /* Env. variable values for scripts */
int s_env_nalloc;       /* # words avail at script_env */

u_char outpacket_buf[PPP_MRU+PPP_HDRLEN]; /* buffer for outgoing packet */
u_char inpacket_buf[PPP_MRU+PPP_HDRLEN]; /* buffer for incoming packet */

static int n_children;        /* # child processes still running */

static int locked;            /* lock() has succeeded */

char *no_ppp_msg = "Sorry - this system lacks PPP kernel support\n";

/* Prototypes for procedures local to this file. */

static void create_pidfile __P((void));
static void cleanup __P((void));
static void close_tty __P((void));
static void get_input __P((void));
static void calltimeout __P((void));
static struct timeval *timeleft __P((struct timeval *));
static void kill_my_pg __P((int));
static void hup __P((int));
static void term __P((int));
static void chld __P((int));
static void toggle_debug __P((int));
static void open_ccp __P((int));
static void bad_signal __P((int));
static void holdoff_end __P((void *));
static int device_script __P((char *, int, int));
static void reap_kids __P((void));
static void pr_log __P((void *, char *, ...));

extern      char  *ttyname __P((int));
extern      char  *getlogin __P((void));
int main __P((int, char *[]));

#ifdef ultrix
#undef      O_NONBLOCK
#define     O_NONBLOCK  O_NDELAY
#endif

#ifdef ULTRIX
#define setlogmask(x)
#endif

/*
 * PPP Data Link Layer "protocol" table.
 * One entry per supported protocol.
 * The last entry must be NULL.
 */
struct protent *protocols[] = {
    &lcp_protent,
    &pap_protent,
    &chap_protent,
#ifdef CBCP_SUPPORT
    &cbcp_protent,
#endif
    &ipcp_protent,
#ifdef INET6
    &ipv6cp_protent,
#endif
    &ccp_protent,
#ifdef IPX_CHANGE
    &ipxcp_protent,
#endif
#ifdef AT_CHANGE
    &atcp_protent,
#endif
    NULL
};

int
main(argc, argv)
    int argc;
    char *argv[];
{
    int i, n, fdflags;
    struct sigaction sa;
    FILE *iffile;
    char *p;
    struct passwd *pw;
    struct timeval timo;
    sigset_t mask;
    struct protent *protp;
    struct stat statbuf;
    int connect_attempts = 0;
    char numbuf[16];

    phase = PHASE_INITIALIZE;
    p = ttyname(0);
    if (p)
      strcpy(devnam, p);
    strcpy(default_devnam, devnam);

    script_env = NULL;

    /* Initialize syslog facilities */
#ifdef ULTRIX
    openlog("pppd", LOG_PID);
#else
    openlog("pppd", LOG_PID | LOG_NDELAY, LOG_PPP);
    setlogmask(LOG_UPTO(LOG_INFO));
#endif

    if (gethostname(hostname, MAXNAMELEN) < 0 ) {
      option_error("Couldn't get hostname: %m");
      die(1);
    }
    hostname[MAXNAMELEN-1] = 0;

    uid = getuid();
    privileged = uid == 0;
    sprintf(numbuf, "%d", uid);
    script_setenv("UID", numbuf);

    /*
     * Initialize to the standard option set, then parse, in order,
     * the system options file, the user's options file,
     * the tty's options file, and the command line arguments.
     */
    for (i = 0; (protp = protocols[i]) != NULL; ++i)
        (*protp->init)(0);

    progname = *argv;

    if (!options_from_file(_PATH_SYSOPTIONS, !privileged, 0, 1)
      || !options_from_user())
      exit(1);
    scan_args(argc-1, argv+1);      /* look for tty name on command line */
    if (!options_for_tty()
      || !parse_args(argc-1, argv+1))
      exit(1);

    /*
     * Check that we are running as root.
     */
    if (geteuid() != 0) {
      option_error("must be root to run %s, since it is not setuid-root",
                 argv[0]);
      die(1);
    }

    if (!ppp_available()) {
      option_error(no_ppp_msg);
      exit(1);
    }

    /*
     * Check that the options given are valid and consistent.
     */
    sys_check_options();
    auth_check_options();
    for (i = 0; (protp = protocols[i]) != NULL; ++i)
      if (protp->check_options != NULL)
          (*protp->check_options)();
    if (demand && connector == 0) {
      option_error("connect script required for demand-dialling\n");
      exit(1);
    }

    script_setenv("DEVICE", devnam);
    sprintf(numbuf, "%d", baud_rate);
    script_setenv("SPEED", numbuf);

    /*
     * If the user has specified the default device name explicitly,
     * pretend they hadn't.
     */
    if (!default_device && strcmp(devnam, default_devnam) == 0)
      default_device = 1;
    if (default_device)
      nodetach = 1;

    /*
     * Initialize system-dependent stuff and magic number package.
     */
    sys_init();
    magic_init();
    if (debug)
      setlogmask(LOG_UPTO(LOG_DEBUG));

    /*
     * Detach ourselves from the terminal, if required,
     * and identify who is running us.
     */
    if (nodetach == 0)
      detach();
    pid = getpid();
    p = getlogin();
    stime = time((time_t *) NULL);
    if (p == NULL) {
      pw = getpwuid(uid);
      if (pw != NULL && pw->pw_name != NULL)
          p = pw->pw_name;
      else
          p = "(unknown)";
    }
    syslog(LOG_NOTICE, "pppd %s.%d%s started by %s, uid %d",
         VERSION, PATCHLEVEL, IMPLEMENTATION, p, uid);
  
    /*
     * Compute mask of all interesting signals and install signal handlers
     * for each.  Only one signal handler may be active at a time.  Therefore,
     * all other signals should be masked when any handler is executing.
     */
    sigemptyset(&mask);
    sigaddset(&mask, SIGHUP);
    sigaddset(&mask, SIGINT);
    sigaddset(&mask, SIGTERM);
    sigaddset(&mask, SIGCHLD);

#define SIGNAL(s, handler)    { \
      sa.sa_handler = handler; \
      if (sigaction(s, &sa, NULL) < 0) { \
          syslog(LOG_ERR, "Couldn't establish signal handler (%d): %m", s); \
          die(1); \
      } \
    }

    sa.sa_mask = mask;
    sa.sa_flags = 0;
    SIGNAL(SIGHUP, hup);            /* Hangup */
    SIGNAL(SIGINT, term);           /* Interrupt */
    SIGNAL(SIGTERM, term);          /* Terminate */
    SIGNAL(SIGCHLD, chld);

    SIGNAL(SIGUSR1, toggle_debug);  /* Toggle debug flag */
    SIGNAL(SIGUSR2, open_ccp);            /* Reopen CCP */

    /*
     * Install a handler for other signals which would otherwise
     * cause pppd to exit without cleaning up.
     */
    SIGNAL(SIGABRT, bad_signal);
    SIGNAL(SIGALRM, bad_signal);
    SIGNAL(SIGFPE, bad_signal);
    SIGNAL(SIGILL, bad_signal);
    SIGNAL(SIGPIPE, bad_signal);
    SIGNAL(SIGQUIT, bad_signal);
    SIGNAL(SIGSEGV, bad_signal);
#ifdef SIGBUS
    SIGNAL(SIGBUS, bad_signal);
#endif
#ifdef SIGEMT
    SIGNAL(SIGEMT, bad_signal);
#endif
#ifdef SIGPOLL
    SIGNAL(SIGPOLL, bad_signal);
#endif
#ifdef SIGPROF
    SIGNAL(SIGPROF, bad_signal);
#endif
#ifdef SIGSYS
    SIGNAL(SIGSYS, bad_signal);
#endif
#ifdef SIGTRAP
    SIGNAL(SIGTRAP, bad_signal);
#endif
#ifdef SIGVTALRM
    SIGNAL(SIGVTALRM, bad_signal);
#endif
#ifdef SIGXCPU
    SIGNAL(SIGXCPU, bad_signal);
#endif
#ifdef SIGXFSZ
    SIGNAL(SIGXFSZ, bad_signal);
#endif

    /*
     * Apparently we can get a SIGPIPE when we call syslog, if
     * syslogd has died and been restarted.  Ignoring it seems
     * be sufficient.
     */
    signal(SIGPIPE, SIG_IGN);

    /*
     * If we're doing dial-on-demand, set up the interface now.
     */
    if (demand) {
      /*
       * Open the loopback channel and set it up to be the ppp interface.
       */
      open_ppp_loopback();

      syslog(LOG_INFO, "Using interface ppp%d", ifunit);
      (void) sprintf(ifname, "ppp%d", ifunit);
      script_setenv("IFNAME", ifname);

      create_pidfile(); /* write pid to file */

      /*
       * Configure the interface and mark it up, etc.
       */
      demand_conf();
    }

    for (;;) {

      need_holdoff = 1;

      if (demand) {
          /*
           * Don't do anything until we see some activity.
           */
          phase = PHASE_DORMANT;
          kill_link = 0;
          demand_unblock();
          for (;;) {
            wait_loop_output(timeleft(&timo));
            calltimeout();
            if (kill_link) {
                if (!persist)
                  die(0);
                kill_link = 0;
            }
            if (get_loop_output())
                break;
            reap_kids();
          }

          /*
           * Now we want to bring up the link.
           */
          demand_block();
          syslog(LOG_INFO, "Starting link");
      }

      /*
       * Lock the device if we've been asked to.
       */
      if (lockflag && !default_device) {
          if (lock(devnam) < 0)
            goto fail;
          locked = 1;
      }

      /*
       * Open the serial device and set it up to be the ppp interface.
       * First we open it in non-blocking mode so we can set the
       * various termios flags appropriately.  If we aren't dialling
       * out and we want to use the modem lines, we reopen it later
       * in order to wait for the carrier detect signal from the modem.
       */
      while ((ttyfd = open(devnam, O_NONBLOCK | O_RDWR, 0)) < 0) {
          if (errno != EINTR)
            syslog(LOG_ERR, "Failed to open %s: %m", devnam);
          if (!persist || errno != EINTR)
            goto fail;
      }
      if ((fdflags = fcntl(ttyfd, F_GETFL)) == -1
          || fcntl(ttyfd, F_SETFL, fdflags & ~O_NONBLOCK) < 0)
          syslog(LOG_WARNING,
               "Couldn't reset non-blocking mode on device: %m");

      hungup = 0;
      kill_link = 0;

      /*
       * Do the equivalent of `mesg n' to stop broadcast messages.
       */
      if (fstat(ttyfd, &statbuf) < 0
          || fchmod(ttyfd, statbuf.st_mode & ~(S_IWGRP | S_IWOTH)) < 0) {
          syslog(LOG_WARNING,
               "Couldn't restrict write permissions to %s: %m", devnam);
      } else
          tty_mode = statbuf.st_mode;

      /* run connection script */
      if (connector && connector[0]) {
          MAINDEBUG((LOG_INFO, "Connecting with <%s>", connector));

          /*
           * Set line speed, flow control, etc.
           * On most systems we set CLOCAL for now so that we can talk
           * to the modem before carrier comes up.  But this has the
           * side effect that we might miss it if CD drops before we
           * get to clear CLOCAL below.  On systems where we can talk
           * successfully to the modem with CLOCAL clear and CD down,
           * we can clear CLOCAL at this point.
           */
          set_up_tty(ttyfd, 1);

          /* drop dtr to hang up in case modem is off hook */
          if (!default_device && modem) {
            setdtr(ttyfd, FALSE);
            sleep(1);
            setdtr(ttyfd, TRUE);
          }

          if (device_script(connector, ttyfd, ttyfd) < 0) {
            syslog(LOG_ERR, "Connect script failed");
            setdtr(ttyfd, FALSE);
            connect_attempts++;
            goto fail;
          }


          syslog(LOG_INFO, "Serial connection established.");
          sleep(1);           /* give it time to set up its terminal */
      }

      connect_attempts = 0;   /* we made it through ok */

      /* set line speed, flow control, etc.; clear CLOCAL if modem option */
      set_up_tty(ttyfd, 0);

      /* reopen tty if necessary to wait for carrier */
      if (connector == NULL && modem) {
          while ((i = open(devnam, O_RDWR)) < 0) {
            if (errno != EINTR)
                syslog(LOG_ERR, "Failed to reopen %s: %m", devnam);
            if (!persist || errno != EINTR ||
                  hungup || kill_link)
                goto fail;
          }
          close(i);
      }

      /* run welcome script, if any */
      if (welcomer && welcomer[0]) {
          if (device_script(welcomer, ttyfd, ttyfd) < 0)
            syslog(LOG_WARNING, "Welcome script failed");
      }

      /* set up the serial device as a ppp interface */
      establish_ppp(ttyfd);

      if (!demand) {
          
          syslog(LOG_INFO, "Using interface ppp%d", ifunit);
          (void) sprintf(ifname, "ppp%d", ifunit);
          
          create_pidfile();   /* write pid to file */

          /* write interface unit number to file */
          for (n = strlen(devnam); n > 0 ; n--)
                if (devnam[n] == '/') { 
                      n++;
                      break;
                }
          (void) sprintf(iffilename, "%s%s.if", _PATH_VARRUN, &devnam[n]);
          if ((iffile = fopen(iffilename, "w")) != NULL) {
            fprintf(iffile, "ppp%d\n", ifunit);
            (void) fclose(iffile);
          } else {
            syslog(LOG_ERR, "Failed to create if file %s: %m", iffilename);
            iffilename[0] = 0;
          }

          script_setenv("IFNAME", ifname);
      }

      /*
       * Start opening the connection and wait for
       * incoming events (reply, timeout, etc.).
       */
      syslog(LOG_NOTICE, "Connect: %s <--> %s", ifname, devnam);
      stime = time((time_t *) NULL);
      lcp_lowerup(0);
      lcp_open(0);            /* Start protocol */
      for (phase = PHASE_ESTABLISH; phase != PHASE_DEAD; ) {
          wait_input(timeleft(&timo));
          calltimeout();
          get_input();
          if (kill_link) {
            lcp_close(0, "User request");
            kill_link = 0;
          }
          if (open_ccp_flag) {
            if (phase == PHASE_NETWORK) {
                ccp_fsm[0].flags = OPT_RESTART; /* clears OPT_SILENT */
                (*ccp_protent.open)(0);
            }
            open_ccp_flag = 0;
          }
          reap_kids();  /* Don't leave dead kids lying around */
      }

      /*
       * If we may want to bring the link up again, transfer
       * the ppp unit back to the loopback.  Set the
       * real serial device back to its normal mode of operation.
       */
      clean_check();
      if (demand)
          restore_loop();
      disestablish_ppp(ttyfd);

      /*
       * Run disconnector script, if requested.
       * XXX we may not be able to do this if the line has hung up!
       */
      if (disconnector && !hungup) {
          set_up_tty(ttyfd, 1);
          if (device_script(disconnector, ttyfd, ttyfd) < 0) {
            syslog(LOG_WARNING, "disconnect script failed");
          } else {
            syslog(LOG_INFO, "Serial link disconnected.");
          }
      }

    fail:
      if (ttyfd >= 0)
          close_tty();
      if (locked) {
          unlock();
          locked = 0;
      }

      if (!demand) {
          if (pidfilename[0] != 0
            && unlink(pidfilename) < 0 && errno != ENOENT) 
            syslog(LOG_WARNING, "unable to delete pid file: %m");
          pidfilename[0] = 0;

          if (iffile)
                if (unlink(iffilename) < 0 && errno != ENOENT) 
                      syslog(LOG_WARNING, "unable to delete if file: %m");
          iffilename[0] = 0;
      }

      /* limit to retries? */
      if (max_con_attempts)
          if (connect_attempts >= max_con_attempts)
            break;

      if (!persist)
          die(1);

      if (demand)
          demand_discard();
      if (holdoff > 0 && need_holdoff) {
          phase = PHASE_HOLDOFF;
          TIMEOUT(holdoff_end, NULL, holdoff);
          do {
            wait_time(timeleft(&timo));
            calltimeout();
            if (kill_link) {
                if (!persist)
                  die(0);
                kill_link = 0;
                phase = PHASE_DORMANT; /* allow signal to end holdoff */
            }
            reap_kids();
          } while (phase == PHASE_HOLDOFF);
      }
    }

    die(0);
    return 0;
}

/*
 * detach - detach us from the controlling terminal.
 */
void
detach()
{
    if (detached)
      return;
    if (daemon(0, 0) < 0) {
      perror("Couldn't detach from controlling terminal");
      die(1);
    }
    detached = 1;
    pid = getpid();
    /* update pid file if it has been written already */
    if (pidfilename[0])
      create_pidfile();
}

/*
 * Create a file containing our process ID.
 */
static void
create_pidfile()
{
    FILE *pidfile;

    (void) sprintf(pidfilename, "%s%s.pid", _PATH_VARRUN, ifname);
    if ((pidfile = fopen(pidfilename, "w")) != NULL) {
      fprintf(pidfile, "%d\n", pid);
      (void) fclose(pidfile);
    } else {
      syslog(LOG_ERR, "Failed to create pid file %s: %m", pidfilename);
      pidfilename[0] = 0;
    }
}

/*
 * holdoff_end - called via a timeout when the holdoff period ends.
 */
static void
holdoff_end(arg)
    void *arg;
{
    phase = PHASE_DORMANT;
}

/*
 * get_input - called when incoming data is available.
 */
static void
get_input()
{
    int len, i;
    u_char *p;
    u_short protocol;
    struct protent *protp;

    p = inpacket_buf;   /* point to beginning of packet buffer */

    len = read_packet(inpacket_buf);
    if (len < 0)
      return;

    if (len == 0) {
      etime = time((time_t *) NULL);
      minutes = (etime-stime)/60;
      syslog(LOG_NOTICE, "Modem hangup, connected for %d minutes", (minutes >1) ? minutes : 1);
      hungup = 1;
      lcp_lowerdown(0); /* serial link is no longer available */
      link_terminated(0);
      return;
    }

    if (debug /*&& (debugflags & DBG_INPACKET)*/)
      log_packet(p, len, "rcvd ", LOG_DEBUG);

    if (len < PPP_HDRLEN) {
      MAINDEBUG((LOG_INFO, "io(): Received short packet."));
      return;
    }

    p += 2;                   /* Skip address and control */
    GETSHORT(protocol, p);
    len -= PPP_HDRLEN;

    /*
     * Toss all non-LCP packets unless LCP is OPEN.
     */
    if (protocol != PPP_LCP && lcp_fsm[0].state != OPENED) {
      MAINDEBUG((LOG_INFO,
               "get_input: Received non-LCP packet when LCP not open."));
      return;
    }

    /*
     * Until we get past the authentication phase, toss all packets
     * except LCP, LQR and authentication packets.
     */
    if (phase <= PHASE_AUTHENTICATE
      && !(protocol == PPP_LCP || protocol == PPP_LQR
           || protocol == PPP_PAP || protocol == PPP_CHAP)) {
      MAINDEBUG((LOG_INFO, "get_input: discarding proto 0x%x in phase %d",
               protocol, phase));
      return;
    }

    /*
     * Upcall the proper protocol input routine.
     */
    for (i = 0; (protp = protocols[i]) != NULL; ++i) {
      if (protp->protocol == protocol && protp->enabled_flag) {
          (*protp->input)(0, p, len);
          return;
      }
        if (protocol == (protp->protocol & ~0x8000) && protp->enabled_flag
          && protp->datainput != NULL) {
          (*protp->datainput)(0, p, len);
          return;
      }
    }

    if (debug)
      syslog(LOG_WARNING, "Unsupported protocol (0x%x) received", protocol);
    lcp_sprotrej(0, p - PPP_HDRLEN, len + PPP_HDRLEN);
}


/*
 * quit - Clean up state and exit (with an error indication).
 */
void 
quit()
{
    die(1);
}

/*
 * die - like quit, except we can specify an exit status.
 */
void
die(status)
    int status;
{
    cleanup();
    syslog(LOG_INFO, "Exit.");
    exit(status);
}

/*
 * cleanup - restore anything which needs to be restored before we exit
 */
/* ARGSUSED */
static void
cleanup()
{
    sys_cleanup();

    if (ttyfd >= 0)
      close_tty();

    if (pidfilename[0] != 0 && unlink(pidfilename) < 0 && errno != ENOENT) 
      syslog(LOG_WARNING, "unable to delete pid file: %m");
    pidfilename[0] = 0;

    if (locked)
      unlock();
}

/*
 * close_tty - restore the terminal device and close it.
 */
static void
close_tty()
{
    disestablish_ppp(ttyfd);

    /* drop dtr to hang up */
    if (modem) {
      setdtr(ttyfd, FALSE);
      /*
       * This sleep is in case the serial port has CLOCAL set by default,
       * and consequently will reassert DTR when we close the device.
       */
      sleep(1);
    }

    restore_tty(ttyfd);

    if (tty_mode != (mode_t) -1)
      fchmod(ttyfd, tty_mode);

    close(ttyfd);
    ttyfd = -1;
}


struct      callout {
    struct timeval      c_time;           /* time at which to call routine */
    void          *c_arg;           /* argument to routine */
    void          (*c_func) __P((void *)); /* routine */
    struct        callout *c_next;
};

static struct callout *callout = NULL;    /* Callout list */
static struct timeval timenow;            /* Current time */

/*
 * timeout - Schedule a timeout.
 *
 * Note that this timeout takes the number of seconds, NOT hz (as in
 * the kernel).
 */
void
timeout(func, arg, time)
    void (*func) __P((void *));
    void *arg;
    int time;
{
    struct callout *newp, *p, **pp;
  
    MAINDEBUG((LOG_DEBUG, "Timeout %lx:%lx in %d seconds.",
             (long) func, (long) arg, time));
  
    /*
     * Allocate timeout.
     */
    if ((newp = (struct callout *) malloc(sizeof(struct callout))) == NULL) {
      syslog(LOG_ERR, "Out of memory in timeout()!");
      die(1);
    }
    newp->c_arg = arg;
    newp->c_func = func;
    gettimeofday(&timenow, NULL);
    newp->c_time.tv_sec = timenow.tv_sec + time;
    newp->c_time.tv_usec = timenow.tv_usec;
  
    /*
     * Find correct place and link it in.
     */
    for (pp = &callout; (p = *pp); pp = &p->c_next)
      if (newp->c_time.tv_sec < p->c_time.tv_sec
          || (newp->c_time.tv_sec == p->c_time.tv_sec
            && newp->c_time.tv_usec < p->c_time.tv_sec))
          break;
    newp->c_next = p;
    *pp = newp;
}


/*
 * untimeout - Unschedule a timeout.
 */
void
untimeout(func, arg)
    void (*func) __P((void *));
    void *arg;
{
    struct callout **copp, *freep;
  
    MAINDEBUG((LOG_DEBUG, "Untimeout %lx:%lx.", (long) func, (long) arg));
  
    /*
     * Find first matching timeout and remove it from the list.
     */
    for (copp = &callout; (freep = *copp); copp = &freep->c_next)
      if (freep->c_func == func && freep->c_arg == arg) {
          *copp = freep->c_next;
          (void) free((char *) freep);
          break;
      }
}


/*
 * calltimeout - Call any timeout routines which are now due.
 */
static void
calltimeout()
{
    struct callout *p;

    while (callout != NULL) {
      p = callout;

      if (gettimeofday(&timenow, NULL) < 0) {
          syslog(LOG_ERR, "Failed to get time of day: %m");
          die(1);
      }
      if (!(p->c_time.tv_sec < timenow.tv_sec
            || (p->c_time.tv_sec == timenow.tv_sec
              && p->c_time.tv_usec <= timenow.tv_usec)))
          break;        /* no, it's not time yet */

      callout = p->c_next;
      (*p->c_func)(p->c_arg);

      free((char *) p);
    }
}


/*
 * timeleft - return the length of time until the next timeout is due.
 */
static struct timeval *
timeleft(tvp)
    struct timeval *tvp;
{
    if (callout == NULL)
      return NULL;

    gettimeofday(&timenow, NULL);
    tvp->tv_sec = callout->c_time.tv_sec - timenow.tv_sec;
    tvp->tv_usec = callout->c_time.tv_usec - timenow.tv_usec;
    if (tvp->tv_usec < 0) {
      tvp->tv_usec += 1000000;
      tvp->tv_sec -= 1;
    }
    if (tvp->tv_sec < 0)
      tvp->tv_sec = tvp->tv_usec = 0;

    return tvp;
}


/*
 * kill_my_pg - send a signal to our process group, and ignore it ourselves.
 */
static void
kill_my_pg(sig)
    int sig;
{
    struct sigaction act, oldact;

    act.sa_handler = SIG_IGN;
    act.sa_flags = 0;
    kill(0, sig);
    sigaction(sig, &act, &oldact);
    sigaction(sig, &oldact, NULL);
}


/*
 * hup - Catch SIGHUP signal.
 *
 * Indicates that the physical layer has been disconnected.
 * We don't rely on this indication; if the user has sent this
 * signal, we just take the link down.
 */
static void
hup(sig)
    int sig;
{
    syslog(LOG_INFO, "Hangup (SIGHUP)");
    kill_link = 1;
    if (conn_running)
      /* Send the signal to the [dis]connector process(es) also */
      kill_my_pg(sig);
}


/*
 * term - Catch SIGTERM signal and SIGINT signal (^C/del).
 *
 * Indicates that we should initiate a graceful disconnect and exit.
 */
/*ARGSUSED*/
static void
term(sig)
    int sig;
{
    syslog(LOG_INFO, "Terminating on signal %d.", sig);
    persist = 0;        /* don't try to restart */
    kill_link = 1;
    if (conn_running)
      /* Send the signal to the [dis]connector process(es) also */
      kill_my_pg(sig);
}


/*
 * chld - Catch SIGCHLD signal.
 * Calls reap_kids to get status for any dead kids.
 */
static void
chld(sig)
    int sig;
{
    reap_kids();
}


/*
 * toggle_debug - Catch SIGUSR1 signal.
 *
 * Toggle debug flag.
 */
/*ARGSUSED*/
static void
toggle_debug(sig)
    int sig;
{
    debug = !debug;
    if (debug) {
      setlogmask(LOG_UPTO(LOG_DEBUG));
    } else {
      setlogmask(LOG_UPTO(LOG_WARNING));
    }
}


/*
 * open_ccp - Catch SIGUSR2 signal.
 *
 * Try to (re)negotiate compression.
 */
/*ARGSUSED*/
static void
open_ccp(sig)
    int sig;
{
    open_ccp_flag = 1;
}


/*
 * bad_signal - We've caught a fatal signal.  Clean up state and exit.
 */
static void
bad_signal(sig)
    int sig;
{
    static int crashed = 0;

    if (crashed)
      _exit(127);
    crashed = 1;
    syslog(LOG_ERR, "Fatal signal %d", sig);
    if (conn_running)
      kill_my_pg(SIGTERM);
    die(1);
}


/*
 * device_script - run a program to connect or disconnect the
 * serial device.
 */
static int
device_script(program, in, out)
    char *program;
    int in, out;
{
    int pid;
    int status;
    int errfd;

    conn_running = 1;
    pid = fork();

    if (pid < 0) {
      conn_running = 0;
      syslog(LOG_ERR, "Failed to create child process: %m");
      die(1);
    }

    if (pid == 0) {
      sys_close();
      closelog();
      if (in == out) {
          if (in != 0) {
            dup2(in, 0);
            close(in);
          }
          dup2(0, 1);
      } else {
          if (out == 0)
            out = dup(out);
          if (in != 0) {
            dup2(in, 0);
            close(in);
          }
          if (out != 1) {
            dup2(out, 1);
            close(out);
          }
      }
      if (nodetach == 0) {
          close(2);
          errfd = open(_PATH_CONNERRS, O_WRONLY | O_APPEND | O_CREAT, 0600);
          if (errfd >= 0 && errfd != 2) {
            dup2(errfd, 2);
            close(errfd);
          }
      }
      setuid(getuid());
      setgid(getgid());
      execl("/bin/sh", "sh", "-c", program, (char *)0);
      syslog(LOG_ERR, "could not exec /bin/sh: %m");
      _exit(99);
      /* NOTREACHED */
    }

    while (waitpid(pid, &status, 0) < 0) {
      if (errno == EINTR)
          continue;
      syslog(LOG_ERR, "error waiting for (dis)connection process: %m");
      die(1);
    }
    conn_running = 0;

    return (status == 0 ? 0 : -1);
}


/*
 * run-program - execute a program with given arguments,
 * but don't wait for it.
 * If the program can't be executed, logs an error unless
 * must_exist is 0 and the program file doesn't exist.
 */
int
run_program(prog, args, must_exist)
    char *prog;
    char **args;
    int must_exist;
{
    int pid;

    pid = fork();
    if (pid == -1) {
      syslog(LOG_ERR, "Failed to create child process for %s: %m", prog);
      return -1;
    }
    if (pid == 0) {
      int new_fd;

      /* Leave the current location */
      (void) setsid();    /* No controlling tty. */
      (void) umask (S_IRWXG|S_IRWXO);
      (void) chdir ("/"); /* no current directory. */
      setuid(geteuid());
      setgid(getegid());

      /* Ensure that nothing of our device environment is inherited. */
      sys_close();
      closelog();
      close (0);
      close (1);
      close (2);
      close (ttyfd);  /* tty interface to the ppp device */

        /* Don't pass handles to the PPP device, even by accident. */
      new_fd = open (_PATH_DEVNULL, O_RDWR);
      if (new_fd >= 0) {
          if (new_fd != 0) {
              dup2  (new_fd, 0); /* stdin <- /dev/null */
            close (new_fd);
          }
          dup2 (0, 1); /* stdout -> /dev/null */
          dup2 (0, 2); /* stderr -> /dev/null */
      }

#ifdef BSD
      /* Force the priority back to zero if pppd is running higher. */
      if (setpriority (PRIO_PROCESS, 0, 0) < 0)
          syslog (LOG_WARNING, "can't reset priority to 0: %m"); 
#endif

      /* SysV recommends a second fork at this point. */

      /* run the program; give it a null environment */
      execve(prog, args, script_env);
      if (must_exist || errno != ENOENT)
          syslog(LOG_WARNING, "Can't execute %s: %m", prog);
      _exit(-1);
    }
    MAINDEBUG((LOG_DEBUG, "Script %s started; pid = %d", prog, pid));
    ++n_children;
    return 0;
}


/*
 * reap_kids - get status from any dead child processes,
 * and log a message for abnormal terminations.
 */
static void
reap_kids()
{
    int pid, status;

    if (n_children == 0)
      return;
    if ((pid = waitpid(-1, &status, WNOHANG)) == -1) {
      if (errno != ECHILD)
          syslog(LOG_ERR, "Error waiting for child process: %m");
      return;
    }
    if (pid > 0) {
      --n_children;
      if (WIFSIGNALED(status)) {
          syslog(LOG_WARNING, "Child process %d terminated with signal %d",
               pid, WTERMSIG(status));
      }
    }
}


/*
 * log_packet - format a packet and log it.
 */

char line[256];               /* line to be logged accumulated here */
char *linep;

void
log_packet(p, len, prefix, level)
    u_char *p;
    int len;
    char *prefix;
    int level;
{
    strcpy(line, prefix);
    linep = line + strlen(line);
    format_packet(p, len, pr_log, NULL);
    if (linep != line)
      syslog(level, "%s", line);
}

/*
 * format_packet - make a readable representation of a packet,
 * calling `printer(arg, format, ...)' to output it.
 */
void
format_packet(p, len, printer, arg)
    u_char *p;
    int len;
    void (*printer) __P((void *, char *, ...));
    void *arg;
{
    int i, n;
    u_short proto;
    u_char x;
    struct protent *protp;

    if (len >= PPP_HDRLEN && p[0] == PPP_ALLSTATIONS && p[1] == PPP_UI) {
      p += 2;
      GETSHORT(proto, p);
      len -= PPP_HDRLEN;
      for (i = 0; (protp = protocols[i]) != NULL; ++i)
          if (proto == protp->protocol)
            break;
      if (protp != NULL) {
          printer(arg, "[%s", protp->name);
          n = (*protp->printpkt)(p, len, printer, arg);
          printer(arg, "]");
          p += n;
          len -= n;
      } else {
          printer(arg, "[proto=0x%x]", proto);
      }
    }

    for (; len > 0; --len) {
      GETCHAR(x, p);
      printer(arg, " %.2x", x);
    }
}

static void
pr_log __V((void *arg, char *fmt, ...))
{
    int n;
    va_list pvar;
    char buf[256];

#if __STDC__
    va_start(pvar, fmt);
#else
    void *arg;
    char *fmt;
    va_start(pvar);
    arg = va_arg(pvar, void *);
    fmt = va_arg(pvar, char *);
#endif

    n = vfmtmsg(buf, sizeof(buf), fmt, pvar);
    va_end(pvar);

    if (linep + n + 1 > line + sizeof(line)) {
      syslog(LOG_DEBUG, "%s", line);
      linep = line;
    }
    strcpy(linep, buf);
    linep += n;
}

/*
 * print_string - print a readable representation of a string using
 * printer.
 */
void
print_string(p, len, printer, arg)
    char *p;
    int len;
    void (*printer) __P((void *, char *, ...));
    void *arg;
{
    int c;

    printer(arg, "\"");
    for (; len > 0; --len) {
      c = *p++;
      if (' ' <= c && c <= '~') {
          if (c == '\\' || c == '"')
            printer(arg, "\\");
          printer(arg, "%c", c);
      } else {
          switch (c) {
          case '\n':
            printer(arg, "\\n");
            break;
          case '\r':
            printer(arg, "\\r");
            break;
          case '\t':
            printer(arg, "\\t");
            break;
          default:
            printer(arg, "\\%.3o", c);
          }
      }
    }
    printer(arg, "\"");
}

/*
 * novm - log an error message saying we ran out of memory, and die.
 */
void
novm(msg)
    char *msg;
{
    syslog(LOG_ERR, "Virtual memory exhausted allocating %s\n", msg);
    die(1);
}

/*
 * fmtmsg - format a message into a buffer.  Like sprintf except we
 * also specify the length of the output buffer, and we handle
 * %r (recursive format), %m (error message) and %I (IP address) formats.
 * Doesn't do floating-point formats.
 * Returns the number of chars put into buf.
 */
int
fmtmsg __V((char *buf, int buflen, char *fmt, ...))
{
    va_list args;
    int n;

#if __STDC__
    va_start(args, fmt);
#else
    char *buf;
    int buflen;
    char *fmt;
    va_start(args);
    buf = va_arg(args, char *);
    buflen = va_arg(args, int);
    fmt = va_arg(args, char *);
#endif
    n = vfmtmsg(buf, buflen, fmt, args);
    va_end(args);
    return n;
}

/*
 * vfmtmsg - like fmtmsg, takes a va_list instead of a list of args.
 */
#define OUTCHAR(c)      (buflen > 0? (--buflen, *buf++ = (c)): 0)

int
vfmtmsg(buf, buflen, fmt, args)
    char *buf;
    int buflen;
    char *fmt;
    va_list args;
{
    int c, i, n;
    int width, prec, fillch;
    int base, len, neg, quoted;
    unsigned long val = 0;
    char *str, *f, *buf0;
    unsigned char *p;
    char num[32];
    time_t t;
    static char hexchars[] = "0123456789abcdef";

    buf0 = buf;
    --buflen;
    while (buflen > 0) {
      for (f = fmt; *f != '%' && *f != 0; ++f)
          ;
      if (f > fmt) {
          len = f - fmt;
          if (len > buflen)
            len = buflen;
          memcpy(buf, fmt, len);
          buf += len;
          buflen -= len;
          fmt = f;
      }
      if (*fmt == 0)
          break;
      c = *++fmt;
      width = prec = 0;
      fillch = ' ';
      if (c == '0') {
          fillch = '0';
          c = *++fmt;
      }
      if (c == '*') {
          width = va_arg(args, int);
          c = *++fmt;
      } else {
          while (isdigit(c)) {
            width = width * 10 + c - '0';
            c = *++fmt;
          }
      }
      if (c == '.') {
          c = *++fmt;
          if (c == '*') {
            prec = va_arg(args, int);
            c = *++fmt;
          } else {
            while (isdigit(c)) {
                prec = prec * 10 + c - '0';
                c = *++fmt;
            }
          }
      }
      str = 0;
      base = 0;
      neg = 0;
      ++fmt;
      switch (c) {
      case 'd':
          i = va_arg(args, int);
          if (i < 0) {
            neg = 1;
            val = -i;
          } else
            val = i;
          base = 10;
          break;
      case 'o':
          val = va_arg(args, unsigned int);
          base = 8;
          break;
      case 'x':
          val = va_arg(args, unsigned int);
          base = 16;
          break;
      case 'p':
          val = (unsigned long) va_arg(args, void *);
          base = 16;
          neg = 2;
          break;
      case 's':
          str = va_arg(args, char *);
          break;
      case 'c':
          num[0] = va_arg(args, int);
          num[1] = 0;
          str = num;
          break;
      case 'm':
          str = strerror(errno);
          break;
      case 'I':
          str = ip_ntoa(va_arg(args, u_int32_t));
          break;
      case 'r':
          f = va_arg(args, char *);
#if !defined(__powerpc__) && !defined(__amd64__)
          n = vfmtmsg(buf, buflen + 1, f, va_arg(args, va_list));
#else
          /* On the powerpc, a va_list is an array of 1 structure */
          n = vfmtmsg(buf, buflen + 1, f, va_arg(args, void *));
#endif
          buf += n;
          buflen -= n;
          continue;
      case 't':
          time(&t);
          str = ctime(&t);
          str += 4;           /* chop off the day name */
          str[15] = 0;  /* chop off year and newline */
          break;
      case 'v':         /* "visible" string */
      case 'q':         /* quoted string */
          quoted = c == 'q';
          p = va_arg(args, unsigned char *);
          if (fillch == '0' && prec > 0) {
            n = prec;
          } else {
            n = strlen((char *)p);
            if (prec > 0 && prec < n)
                n = prec;
          }
          while (n > 0 && buflen > 0) {
            c = *p++;
            --n;
            if (!quoted && c >= 0x80) {
                OUTCHAR('M');
                OUTCHAR('-');
                c -= 0x80;
            }
            if (quoted && (c == '"' || c == '\\'))
                OUTCHAR('\\');
            if (c < 0x20 || (0x7f <= c && c < 0xa0)) {
                if (quoted) {
                  OUTCHAR('\\');
                  switch (c) {
                  case '\t':  OUTCHAR('t');     break;
                  case '\n':  OUTCHAR('n');     break;
                  case '\b':  OUTCHAR('b');     break;
                  case '\f':  OUTCHAR('f');     break;
                  default:
                      OUTCHAR('x');
                      OUTCHAR(hexchars[c >> 4]);
                      OUTCHAR(hexchars[c & 0xf]);
                  }
                } else {
                  if (c == '\t')
                      OUTCHAR(c);
                  else {
                      OUTCHAR('^');
                      OUTCHAR(c ^ 0x40);
                  }
                }
            } else
                OUTCHAR(c);
          }
          continue;
      default:
          *buf++ = '%';
          if (c != '%')
            --fmt;            /* so %z outputs %z etc. */
          --buflen;
          continue;
      }
      if (base != 0) {
          str = num + sizeof(num);
          *--str = 0;
          while (str > num + neg) {
            *--str = hexchars[val % base];
            val = val / base;
            if (--prec <= 0 && val == 0)
                break;
          }
          switch (neg) {
          case 1:
            *--str = '-';
            break;
          case 2:
            *--str = 'x';
            *--str = '0';
            break;
          }
          len = num + sizeof(num) - 1 - str;
      } else {
          len = strlen(str);
          if (prec > 0 && len > prec)
            len = prec;
      }
      if (width > 0) {
          if (width > buflen)
            width = buflen;
          if ((n = width - len) > 0) {
            buflen -= n;
            for (; n > 0; --n)
                *buf++ = fillch;
          }
      }
      if (len > buflen)
          len = buflen;
      memcpy(buf, str, len);
      buf += len;
      buflen -= len;
    }
    *buf = 0;
    return buf - buf0;
}

/*
 * script_setenv - set an environment variable value to be used
 * for scripts that we run (e.g. ip-up, auth-up, etc.)
 */
void
script_setenv(var, value)
    char *var, *value;
{
    int vl = strlen(var);
    int i;
    char *p, *newstring;

    newstring = (char *) malloc(vl + strlen(value) + 2);
    if (newstring == 0)
      return;
    strcpy(newstring, var);
    newstring[vl] = '=';
    strcpy(newstring+vl+1, value);

    /* check if this variable is already set */
    if (script_env != 0) {
      for (i = 0; (p = script_env[i]) != 0; ++i) {
          if (strncmp(p, var, vl) == 0 && p[vl] == '=') {
            free(p);
            script_env[i] = newstring;
            return;
          }
      }
    } else {
      i = 0;
      script_env = (char **) malloc(16 * sizeof(char *));
      if (script_env == 0)
          return;
      s_env_nalloc = 16;
    }

    /* reallocate script_env with more space if needed */
    if (i + 1 >= s_env_nalloc) {
      int new_n = i + 17;
      char **newenv = (char **) realloc((void *)script_env,
                                new_n * sizeof(char *));
      if (newenv == 0)
          return;
      script_env = newenv;
      s_env_nalloc = new_n;
    }

    script_env[i] = newstring;
    script_env[i+1] = 0;
}

/*
 * script_unsetenv - remove a variable from the environment
 * for scripts.
 */
void
script_unsetenv(var)
    char *var;
{
    int vl = strlen(var);
    int i;
    char *p;

    if (script_env == 0)
      return;
    for (i = 0; (p = script_env[i]) != 0; ++i) {
      if (strncmp(p, var, vl) == 0 && p[vl] == '=') {
          free(p);
          while ((script_env[i] = script_env[i+1]) != 0)
            ++i;
          break;
      }
    }
}

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