text: /*
   * sys-next.c - System-dependent procedures for setting up
   * PPP interfaces on NeXT 3.2/3.3  systems
   *
   * Copyright (c) 1989 Carnegie Mellon University.
   * Copyright (c) 1994 Philippe-Andre Prindeville.
   * 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[] = "$Id: sys-NeXT.c,v 1.1.1.1 1999/11/22 03:47:55 christ Exp $";
  #endif
  
  #include <stdio.h>
  #include <termios.h>
  #include <utmp.h>
  #include <unistd.h>
  #include <stdlib.h>
  #include <libc.h>
  #include <strings.h>
  #include <sys/types.h>
  #include <sys/file.h>
  #include <sys/socket.h>
  #include <sys/ioctl.h>
  #include <sys/time.h>
  #include <sys/errno.h>
  #include <sys/stat.h>
  #include <sys/fcntl.h>
  
  #include <net/if.h>
  #include <net/ppp_defs.h>
  #include <net/if_ppp.h>
  #include <netdb.h>
  #include <netinet/in.h>
  #include <netinet/in_systm.h>
  #include <netinet/in_var.h>
  #if !(NS_TARGET >= 40)
  /* XXX get an error "duplicate member ip_v under 4.1 GAMMA */
  #include <netinet/ip.h>
  #endif /* NS_TARGET */
  #include <netinet/if_ether.h>
  #include <net/route.h>
  #include <netinet/in.h>
  
  #include <netinfo/ni.h>
  
  #include "pppd.h"
  
  static int initdisc = -1;	/* Initial TTY discipline */
  static int initfdflags = -1;	/* Initial file descriptor flags for fd */
  static int ppp_fd = -1;		/* fd which is set to PPP discipline */
  static int loop_slave = -1;
  static int loop_master;
  static char loop_name[20];
  
  static fd_set in_fds;		/* set of fds that wait_input waits for */
  static int max_in_fd;		/* highest fd set in in_fds */
  
  extern int errno;
  
  static int	restore_term;	/* 1 => we've munged the terminal */
  static struct termios inittermios; /* Initial TTY termios */
  
  static int sockfd;		/* socket for doing interface ioctls */
  static int pppdev;  /* +++ */
  
  #if defined(i386) && defined(HAS_BROKEN_IOCTL)
  #define	ioctl	myioctl
  #endif
  
  static int if_is_up;		/* the interface is currently up */
  static u_int32_t default_route_gateway;	/* gateway addr for default route */
  static u_int32_t proxy_arp_addr;	/* remote addr for proxy arp */
  
  /* Prototypes for procedures local to this file. */
  static int translate_speed __P((int));
  static int baud_rate_of __P((int));
  static int dodefaultroute __P((u_int32_t, int));
  static int get_ether_addr __P((u_int32_t, struct sockaddr *));
  static int ether_by_host __P((char *, struct ether_addr *));
  
  
  /*
   * sys_init - System-dependent initialization.
   */
  void
  sys_init()
  {
      openlog("pppd", LOG_PID | LOG_NDELAY, LOG_PPP);
      setlogmask(LOG_UPTO(LOG_INFO));
  
      /* Get an internet socket for doing socket ioctl's on. */
      if ((sockfd = socket(AF_INET, SOCK_DGRAM, 0)) < 0)
  	fatal("Couldn't create IP socket: %m");
  
      if((pppdev = open("/dev/ppp0", O_RDWR, O_NONBLOCK)) == NULL)
  	fatal("Couldn't open /dev/ppp0: %m");
        
      FD_ZERO(&in_fds);
      max_in_fd = 0;
  }
  
  /*
   * sys_cleanup - restore any system state we modified before exiting:
   * mark the interface down, delete default route and/or proxy arp entry.
   * This should call die() because it's called from die().
   */
  void
  sys_cleanup()
  {
      struct ifreq ifr;
  
      if (if_is_up) {
  	strlcpy(ifr.ifr_name, ifname, sizeof(ifr.ifr_name));
  	if (ioctl(sockfd, SIOCGIFFLAGS, &ifr) >= 0
  	    && ((ifr.ifr_flags & IFF_UP) != 0)) {
  	    ifr.ifr_flags &= ~IFF_UP;
  	    ioctl(sockfd, SIOCSIFFLAGS, &ifr);
  	}
      }
  
      if (default_route_gateway)
  	cifdefaultroute(0, 0, default_route_gateway);
      if (proxy_arp_addr)
  	cifproxyarp(0, proxy_arp_addr);
  
      close(pppdev);
  }
  
  /*
   * ppp_available - check whether the system has any ppp interfaces
   * (in fact we check whether we can do an ioctl on ppp0).
   */
  int
  ppp_available()
  {
      int s, ok;
      struct ifreq ifr;
      extern char *no_ppp_msg;
  
      if ((s = socket(AF_INET, SOCK_DGRAM, 0)) < 0)
  	return 1;		/* can't tell - maybe we're not root */
  
      strlcpy(ifr.ifr_name, "ppp0", sizeof (ifr.ifr_name));
      ok = ioctl(s, SIOCGIFFLAGS, (caddr_t) &ifr) >= 0;
      close(s);
  
      no_ppp_msg = "\
  This system lacks kernel support for PPP.  To include PPP support\n\
  in the kernel, please follow the steps detailed in the README.NeXT\n\
  file in the ppp-2.2 distribution.\n";
  
      return ok;
  }
  
  /*
   * establish_ppp - Turn the serial port into a ppp interface.
   */
  int
  establish_ppp(fd)
      int fd;
  {
      int pppdisc = PPPDISC;
      int x;
  
      if (ioctl(fd, TIOCGETD, &initdisc) < 0)
  	fatal("ioctl(TIOCGETD): %m");
      if (ioctl(fd, TIOCSETD, &pppdisc) < 0)
  	fatal("ioctl(establish TIOCSETD): %m");
  
      /*
       * Find out which interface we were given.
       */
      if (ioctl(fd, PPPIOCGUNIT, &ifunit) < 0)
  	fatal("ioctl(PPPIOCGUNIT): %m");
  
      /*
       * Enable debug in the driver if requested.
       */
      if (kdebugflag) {
  	if (ioctl(fd, PPPIOCGFLAGS, (caddr_t) &x) < 0) {
  	    warn("ioctl(PPPIOCGFLAGS): %m");
  	} else {
  	    x |= (kdebugflag & 0xFF) * SC_DEBUG;
  	    if (ioctl(fd, PPPIOCSFLAGS, (caddr_t) &x) < 0)
  		warn("ioctl(PPPIOCSFLAGS): %m");
  	}
      }
  
      /*
       * Set device for non-blocking reads so PPPD can poll for
       * input from the kernel.
       */
      if ((initfdflags = fcntl(fd, F_GETFL)) == -1
  	|| fcntl(fd, F_SETFL, initfdflags | O_NONBLOCK) == -1) {
  	warn("Couldn't set device to non-blocking mode: %m");
      }
  
      return fd;
  }
  
  
  /*
   * disestablish_ppp - Restore the serial port to normal operation.
   * This shouldn't call die() because it's called from die().
   */
  void
  disestablish_ppp(fd)
      int fd;
  {
      /* Reset non-blocking mode on fd. */
      if (initfdflags != -1 && fcntl(fd, F_SETFL, initfdflags) < 0)
  	warn("Couldn't restore device fd flags: %m");
      initfdflags = -1;
  
      /* Restore old line discipline. */
      if (initdisc >= 0 && ioctl(fd, TIOCSETD, &initdisc) < 0)
  	error("ioctl(TIOCSETD): %m");
      initdisc = -1;
  }
  
  /*
   * Check whether the link seems not to be 8-bit clean.
   */
  void
  clean_check()
  {
      int x;
      char *s;
  
      if (ioctl(ttyfd, PPPIOCGFLAGS, (caddr_t) &x) == 0) {
  	s = NULL;
  	switch (~x & (SC_RCV_B7_0|SC_RCV_B7_1|SC_RCV_EVNP|SC_RCV_ODDP)) {
  	case SC_RCV_B7_0:
  	    s = "bit 7 set to 1";
  	    break;
  	case SC_RCV_B7_1:
  	    s = "bit 7 set to 0";
  	    break;
  	case SC_RCV_EVNP:
  	    s = "odd parity";
  	    break;
  	case SC_RCV_ODDP:
  	    s = "even parity";
  	    break;
  	}
  	if (s != NULL) {
  	    warn("Serial link is not 8-bit clean:");
  	    warn("All received characters had %s", s);
  	}
      }
  }
  
  /*
   * List of valid speeds.
   */
  struct speed {
      int speed_int, speed_val;
  } speeds[] = {
  #ifdef B50
      { 50, B50 },
  #endif
  #ifdef B75
      { 75, B75 },
  #endif
  #ifdef B110
      { 110, B110 },
  #endif
  #ifdef B134
      { 134, B134 },
  #endif
  #ifdef B150
      { 150, B150 },
  #endif
  #ifdef B200
      { 200, B200 },
  #endif
  #ifdef B300
      { 300, B300 },
  #endif
  #ifdef B600
      { 600, B600 },
  #endif
  #ifdef B1200
      { 1200, B1200 },
  #endif
  #ifdef B1800
      { 1800, B1800 },
  #endif
  #ifdef B2000
      { 2000, B2000 },
  #endif
  #ifdef B2400
      { 2400, B2400 },
  #endif
  #ifdef B3600
      { 3600, B3600 },
  #endif
  #ifdef B4800
      { 4800, B4800 },
  #endif
  #ifdef B7200
      { 7200, B7200 },
  #endif
  #ifdef B9600
      { 9600, B9600 },
  #endif
  #ifdef B19200
      { 19200, B19200 },
  #endif
  #ifdef B38400
      { 38400, B38400 },
  #endif
  #ifdef EXTA
      { 19200, EXTA },
  #endif
  #ifdef EXTB
      { 38400, EXTB },
  #endif
  #ifdef B14400
      { 14400, B14400 },
  #endif
  #ifdef B28800
      { 28800, B28800 },
  #endif
  #ifdef B43200
      { 43200, B43200 },
  #endif
  #ifdef B57600
      { 57600, B57600 },
  #endif
  /*
  #ifndef B115200
  #warning Defining B115200
  #define B115200 20
  #endif
  */
  #ifdef B115200
      { 115200, B115200 },
  #endif
      { 0, 0 }
  };
  
  /*
   * Translate from bits/second to a speed_t.
   */
  int
  translate_speed(bps)
      int bps;
  {
      struct speed *speedp;
  
      if (bps == 0)
  	return 0;
      for (speedp = speeds; speedp->speed_int; speedp++)
  	if (bps == speedp->speed_int)
  	    return speedp->speed_val;
      warn("speed %d not supported", bps);
      return 0;
  }
  
  /*
   * Translate from a speed_t to bits/second.
   */
  static int
  baud_rate_of(speed)
      int speed;
  {
      struct speed *speedp;
  
      if (speed == 0)
  	return 0;
      for (speedp = speeds; speedp->speed_int; speedp++)
  	if (speed == speedp->speed_val)
  	    return speedp->speed_int;
      return 0;
  }
  
  
  /*
   * set_up_tty: Set up the serial port on `fd' for 8 bits, no parity,
   * at the requested speed, etc.  If `local' is true, set CLOCAL
   * regardless of whether the modem option was specified.
   */
  void
  set_up_tty(fd, local)
      int fd, local;
  {
      int speed, x, modembits;
      struct termios tios;
  
      if (tcgetattr(fd, &tios) < 0)
  	fatal("tcgetattr: %m");
  
      if (!restore_term)
  	inittermios = tios;
  
      tios.c_cflag &= ~(CSIZE | CSTOPB | PARENB | CLOCAL);
  
      tios.c_cflag |= CS8 | CREAD | HUPCL;
      if (local || !modem)
  	tios.c_cflag |= CLOCAL;
  
      tios.c_iflag = IGNBRK | IGNPAR;
      tios.c_oflag = 0;
      tios.c_lflag = 0;
      tios.c_cc[VMIN] = 1;
      tios.c_cc[VTIME] = 0;
  
      if (crtscts == -2) {
  	tios.c_iflag |= IXON | IXOFF;
  	tios.c_cc[VSTOP] = 0x13;	/* DC3 = XOFF = ^S */
  	tios.c_cc[VSTART] = 0x11;	/* DC1 = XON  = ^Q */
      }
  
      speed = translate_speed(inspeed);
      if (speed) {
  	cfsetospeed(&tios, speed);
  	cfsetispeed(&tios, speed);
      } else {
  	speed = cfgetospeed(&tios);
  	/*
  	 * We can't proceed if the serial port speed is B0,
  	 * since that implies that the serial port is disabled.
  	 */
  	if (speed == B0)
  	    fatal("Baud rate for %s is 0; need explicit baud rate",
  		  devnam);
      }
  
      if (modem) {
        modembits = TIOCM_RTS | TIOCM_CTS;
        if (ioctl(fd, (crtscts ? TIOCMBIS : TIOCMBIC), &modembits) < 0)
  	error("ioctl: TIOCMBIS/BIC: %m");
      }
  
      if (tcsetattr(fd, TCSAFLUSH, &tios) < 0)
  	fatal("tcsetattr: %m");
  
     baud_rate = inspeed = baud_rate_of(speed);
     restore_term = 1;
  }
  
  /*
   * restore_tty - restore the terminal to the saved settings.
   */
  void
  restore_tty(fd)
      int fd;
  {
      if (restore_term) {
  	if (tcsetattr(fd, TCSAFLUSH, &inittermios) < 0)
  	    if (errno != ENXIO)
  		warn("tcsetattr: %m");
  	restore_term = 0;
      }
  }
  
  /*
   * setdtr - control the DTR line on the serial port.
   * This is called from die(), so it shouldn't call die().
   *
   * The write hack is to get NXFax to recognize that there is
   * activity on the port.  Not using the write nukes
   * NXFax's capability to determine port usage.
   *
   */
  void
  setdtr(fd, on)
  int fd, on;
  {
      int modembits = TIOCM_DTR;
  
      if (!on)
        {
  	write(fd, " ", 1);
  	sleep(1);
        }
  
  /*    ioctl(fd, (on? TIOCMBIS: TIOCMBIC), &modembits); */
      ioctl(fd, (on? TIOCSDTR: TIOCCDTR), 0);
  }
  
  
  /*
   * output - Output PPP packet.
   */
  void
  output(unit, p, len)
      int unit;
      u_char *p;
      int len;
  {
      if (debug)
  	dbglog("sent %P", p, len);
  
      if (write(ttyfd, p, len) < 0) {
  	if (errno == EWOULDBLOCK || errno == ENOBUFS
  	    || errno == ENXIO || errno == EIO) {
  	    warn("write: warning: %m");
  	} else {
  	    fatal("write: %m");
  	}
      }
  }
  
  
  /*
   * wait_input - wait until there is data available,
   * for the length of time specified by *timo (indefinite
   * if timo is NULL).
   */
  void
  wait_input(timo)
      struct timeval *timo;
  {
      fd_set ready;
      int n;
  
      ready = in_fds;
      n = select(max_in_fd + 1, &ready, NULL, &ready, timo);
      if (n < 0 && errno != EINTR)
  	fatal("select: %m");
  }
  
  
  /*
   * add_fd - add an fd to the set that wait_input waits for.
   */
  void add_fd(fd)
      int fd;
  {
      FD_SET(fd, &in_fds);
      if (fd > max_in_fd)
  	max_in_fd = fd;
  }
  
  /*
   * remove_fd - remove an fd from the set that wait_input waits for.
   */
  void remove_fd(fd)
      int fd;
  {
      FD_CLR(fd, &in_fds);
  }
  
  /*
   * read_packet - get a PPP packet from the serial device.
   */
  int
  read_packet(buf)
      u_char *buf;
  {
      int len;
  
      if ((len = read(ttyfd, buf, PPP_MTU + PPP_HDRLEN)) < 0) {
  	if (errno == EWOULDBLOCK || errno == EINTR) {
  	    SYSDEBUG(("read: %m"));
  	    return -1;
  	}
  	fatal("read: %m");
      }
      return len;
  }
  
  
  /*
   * ppp_send_config - configure the transmit characteristics of
   * the ppp interface.
   */
  void
  ppp_send_config(unit, mtu, asyncmap, pcomp, accomp)
      int unit, mtu;
      u_int32_t asyncmap;
      int pcomp, accomp;
  {
      u_int x;
      struct ifreq ifr;
  
      strlcpy(ifr.ifr_name, ifname, sizeof (ifr.ifr_name));
      ifr.ifr_mtu = mtu;
      if (ioctl(sockfd, SIOCSIFMTU, (caddr_t) &ifr) < 0)
  	fatal("ioctl(SIOCSIFMTU): %m");
  
      if (ioctl(ttyfd, PPPIOCSASYNCMAP, (caddr_t) &asyncmap) < 0)
  	fatal("ioctl(PPPIOCSASYNCMAP): %m");
  
      if (ioctl(ttyfd, PPPIOCGFLAGS, (caddr_t) &x) < 0)
  	fatal("ioctl(PPPIOCGFLAGS): %m");
  
      x = pcomp? x | SC_COMP_PROT: x &~ SC_COMP_PROT;
      x = accomp? x | SC_COMP_AC: x &~ SC_COMP_AC;
      if (ioctl(ttyfd, PPPIOCSFLAGS, (caddr_t) &x) < 0)
  	fatal("ioctl(PPPIOCSFLAGS): %m");
  }
  
  
  /*
   * ppp_set_xaccm - set the extended transmit ACCM for the interface.
   */
  void
  ppp_set_xaccm(unit, accm)
      int unit;
      ext_accm accm;
  {
      if (ioctl(ttyfd, PPPIOCSXASYNCMAP, accm) < 0 && errno != ENOTTY)
  	warn("ioctl(PPPIOCSXASYNCMAP): %m");
  }
  
  
  /*
   * ppp_recv_config - configure the receive-side characteristics of
   * the ppp interface.
   */
  void
  ppp_recv_config(unit, mru, asyncmap, pcomp, accomp)
      int unit, mru;
      u_int32_t asyncmap;
      int pcomp, accomp;
  {
      int x;
  
      if (ioctl(ttyfd, PPPIOCSMRU, (caddr_t) &mru) < 0)
  	fatal("ioctl(PPPIOCSMRU): %m");
      if (ioctl(ttyfd, PPPIOCSRASYNCMAP, (caddr_t) &asyncmap) < 0)
  	fatal("ioctl(PPPIOCSRASYNCMAP): %m");
      if (ioctl(ttyfd, PPPIOCGFLAGS, (caddr_t) &x) < 0)
  	fatal("ioctl(PPPIOCGFLAGS): %m");
      x = !accomp? x | SC_REJ_COMP_AC: x &~ SC_REJ_COMP_AC;
      if (ioctl(ttyfd, PPPIOCSFLAGS, (caddr_t) &x) < 0)
  	fatal("ioctl(PPPIOCSFLAGS): %m");
  }
  
  /*
   * ccp_test - ask kernel whether a given compression method
   * is acceptable for use.
   */
  int
  ccp_test(unit, opt_ptr, opt_len, for_transmit)
      int unit, opt_len, for_transmit;
      u_char *opt_ptr;
  {
      struct ppp_option_data data;
  
      data.ptr = opt_ptr;
      data.length = opt_len;
      data.transmit = for_transmit;
      if (ioctl(ttyfd, PPPIOCSCOMPRESS, (caddr_t) &data) >= 0)
  	return 1;
      return (errno == ENOBUFS)? 0: -1;
  }
  
  /*
   * ccp_flags_set - inform kernel about the current state of CCP.
   */
  void
  ccp_flags_set(unit, isopen, isup)
      int unit, isopen, isup;
  {
      int x;
  
      if (ioctl(ttyfd, PPPIOCGFLAGS, (caddr_t) &x) < 0) {
  	error("ioctl(PPPIOCGFLAGS): %m");
  	return;
      }
      x = isopen? x | SC_CCP_OPEN: x &~ SC_CCP_OPEN;
      x = isup? x | SC_CCP_UP: x &~ SC_CCP_UP;
      if (ioctl(ttyfd, PPPIOCSFLAGS, (caddr_t) &x) < 0)
  	error("ioctl(PPPIOCSFLAGS): %m");
  }
  
  /*
   * ccp_fatal_error - returns 1 if decompression was disabled as a
   * result of an error detected after decompression of a packet,
   * 0 otherwise.  This is necessary because of patent nonsense.
   */
  int
  ccp_fatal_error(unit)
      int unit;
  {
      int x;
  
      if (ioctl(ttyfd, PPPIOCGFLAGS, (caddr_t) &x) < 0) {
  	error("ioctl(PPPIOCGFLAGS): %m");
  	return 0;
      }
      return x & SC_DC_FERROR;
  }
  
  /*
   * sifvjcomp - config tcp header compression
   */
  int
  sifvjcomp(u, vjcomp, cidcomp, maxcid)
      int u, vjcomp, cidcomp, maxcid;
  {
      u_int x;
  
      if (ioctl(ttyfd, PPPIOCGFLAGS, (caddr_t) &x) < 0) {
  	error("ioctl(PPIOCGFLAGS): %m");
  	return 0;
      }
      x = vjcomp ? x | SC_COMP_TCP: x &~ SC_COMP_TCP;
      x = cidcomp? x & ~SC_NO_TCP_CCID: x | SC_NO_TCP_CCID;
      if (ioctl(ttyfd, PPPIOCSFLAGS, (caddr_t) &x) < 0) {
  	error("ioctl(PPPIOCSFLAGS): %m");
  	return 0;
      }
      if (ioctl(ttyfd, PPPIOCSMAXCID, (caddr_t) &maxcid) < 0) {
  	error("ioctl(PPPIOCSFLAGS): %m");
  	return 0;
      }
      return 1;
  }
  
  /*
   * sifup - Config the interface up and enable IP packets to pass.
   */
  #ifndef SC_ENABLE_IP
  #define SC_ENABLE_IP	0x100	/* compat for old versions of kernel code */
  #endif
  
  int
  sifup(u)
      int u;
  {
      struct ifreq ifr;
      u_int x;
      struct npioctl npi;
  
      strlcpy(ifr.ifr_name, ifname, sizeof (ifr.ifr_name));
      if (ioctl(sockfd, SIOCGIFFLAGS, (caddr_t) &ifr) < 0) {
  	error("ioctl (SIOCGIFFLAGS): %m");
  	return 0;
      }
      ifr.ifr_flags |= IFF_UP;
      if (ioctl(sockfd, SIOCSIFFLAGS, (caddr_t) &ifr) < 0) {
  	error("ioctl(SIOCSIFFLAGS): %m");
  	return 0;
      }
      if_is_up = 1;
      npi.protocol = PPP_IP;
      npi.mode = NPMODE_PASS;
      if (ioctl(ttyfd, PPPIOCSNPMODE, &npi) < 0) {
  	if (errno != ENOTTY) {
  	    error("ioctl(PPPIOCSNPMODE): %m");
  	    return 0;
  	}
  	/* for backwards compatibility */
  	if (ioctl(ttyfd, PPPIOCGFLAGS, (caddr_t) &x) < 0) {
  	    error("ioctl (PPPIOCGFLAGS): %m");
  	    return 0;
  	}
  	x |= SC_ENABLE_IP;
  	if (ioctl(ttyfd, PPPIOCSFLAGS, (caddr_t) &x) < 0) {
  	    error("ioctl(PPPIOCSFLAGS): %m");
  	    return 0;
  	}
      }
      return 1;
  }
  
  /*
   * sifdown - Config the interface down and disable IP.
   */
  int
  sifdown(u)
      int u;
  {
      struct ifreq ifr;
      u_int x;
      int rv;
      struct npioctl npi;
  
      rv = 1;
      npi.protocol = PPP_IP;
      npi.mode = NPMODE_ERROR;
      ioctl(ttyfd, PPPIOCSNPMODE, (caddr_t) &npi);
      /* ignore errors, because ttyfd might have been closed by now. */
  
  
      strlcpy(ifr.ifr_name, ifname, sizeof (ifr.ifr_name));
      if (ioctl(sockfd, SIOCGIFFLAGS, (caddr_t) &ifr) < 0) {
  	error("ioctl (SIOCGIFFLAGS): %m");
  	rv = 0;
      } else {
  	ifr.ifr_flags &= ~IFF_UP;
  	if (ioctl(sockfd, SIOCSIFFLAGS, (caddr_t) &ifr) < 0) {
  	    error("ioctl(SIOCSIFFLAGS): %m");
  	    rv = 0;
  	} else
  	    if_is_up = 0;
      }
      return rv;
  }
  
  /*
   * SET_SA_FAMILY - set the sa_family field of a struct sockaddr,
   * if it exists.
   */
  #define SET_SA_FAMILY(addr, family)		\
      BZERO((char *) &(addr), sizeof(addr));	\
      addr.sa_family = (family); 
  
  /*
   * sifaddr - Config the interface IP addresses and netmask.
   */
  int
  sifaddr(u, o, h, m)
      int u;
      u_int32_t o, h, m;
  {
      int ret;
      struct ifreq ifr;
  
      ret = 1;
      strlcpy(ifr.ifr_name, ifname, sizeof(ifr.ifr_name));
      SET_SA_FAMILY(ifr.ifr_addr, AF_INET);
      ((struct sockaddr_in *) &ifr.ifr_addr)->sin_addr.s_addr = o;
      if (ioctl(sockfd, SIOCSIFADDR, (caddr_t) &ifr) < 0) {
  	error("ioctl(SIOCAIFADDR): %m");
  	ret = 0;
      }
      ((struct sockaddr_in *) &ifr.ifr_dstaddr)->sin_addr.s_addr = h;
      if (ioctl(sockfd, SIOCSIFDSTADDR, (caddr_t) &ifr) < 0) {
  	error("ioctl(SIOCSIFDSTADDR): %m");
  	ret = 0;
      }
      if (m != 0) {
  	((struct sockaddr_in *) &ifr.ifr_addr)->sin_addr.s_addr = m;
  	info("Setting interface mask to %s\n", ip_ntoa(m));
  	if (ioctl(sockfd, SIOCSIFNETMASK, (caddr_t) &ifr) < 0) {
  	    error("ioctl(SIOCSIFNETMASK): %m");
  	    ret = 0;
  	}
      }
      return ret;
  }
  
  /*
   * cifaddr - Clear the interface IP addresses, and delete routes
   * through the interface if possible.
   *
   * N.B.: under NextStep, you can't *delete* an address on an interface,
   * so we change it to 0.0.0.0...  A real hack.  But it simplifies
   * reconnection on the server side.
   */
  int
  cifaddr(u, o, h)
      int u;
      u_int32_t o, h;
  {
      struct rtentry rt;
  
  #if 1
      h = o = 0L;
      (void) sifaddr(u, o, h, 0L);
  #endif
      SET_SA_FAMILY(rt.rt_dst, AF_INET);
      ((struct sockaddr_in *) &rt.rt_dst)->sin_addr.s_addr = h;
      SET_SA_FAMILY(rt.rt_gateway, AF_INET);
      ((struct sockaddr_in *) &rt.rt_gateway)->sin_addr.s_addr = o;
      rt.rt_flags = RTF_HOST;
      if (ioctl(sockfd, SIOCDELRT, (caddr_t) &rt) < 0) {
  	error("ioctl(SIOCDELRT): %m");
  	return 0;
      }
      return 1;
  }
  
  /*
   * sifdefaultroute - assign a default route through the address given.
   */
  int
  sifdefaultroute(u, l, g)
      int u;
      u_int32_t l, g;
  {
      return dodefaultroute(g, 's');
  }
  
  /*
   * cifdefaultroute - delete a default route through the address given.
   */
  int
  cifdefaultroute(u, l, g)
      int u;
      u_int32_t l, g;
  {
      return dodefaultroute(g, 'c');
  }
  
  /*
   * dodefaultroute - talk to a routing socket to add/delete a default route.
   */
  int
  dodefaultroute(g, cmd)
      u_int32_t g;
      int cmd;
  {
      struct rtentry rt;
  
      SET_SA_FAMILY(rt.rt_dst, AF_INET);
      ((struct sockaddr_in *) &rt.rt_dst)->sin_addr.s_addr = 0L;
      SET_SA_FAMILY(rt.rt_gateway, AF_INET);
      ((struct sockaddr_in *) &rt.rt_gateway)->sin_addr.s_addr = g;
      rt.rt_flags = RTF_GATEWAY;
      if (ioctl(sockfd, (cmd == 's') ? SIOCADDRT : SIOCDELRT, &rt) < 0) {
  	error("%cifdefaultroute: ioctl(%s): %m", cmd,
  	       (cmd == 's') ? "SIOCADDRT" : "SIOCDELRT");
  	return 0;
      }
      default_route_gateway = (cmd == 's')? g: 0;
      return 1;
  }
  
  /*
   * sifproxyarp - Make a proxy ARP entry for the peer.
   */
  int
  sifproxyarp(unit, hisaddr)
      int unit;
      u_int32_t hisaddr;
  {
      struct arpreq arpreq;
  
      BZERO(&arpreq, sizeof(arpreq));
  
      /*
       * Get the hardware address of an interface on the same subnet
       * as our local address.
       */
      if (!get_ether_addr(hisaddr, &arpreq.arp_ha)) {
  	error("Cannot determine ethernet address for proxy ARP");
  	return 0;
      }
  
      SET_SA_FAMILY(arpreq.arp_pa, AF_INET);
      ((struct sockaddr_in *) &arpreq.arp_pa)->sin_addr.s_addr = hisaddr;
      arpreq.arp_flags = ATF_PERM | ATF_PUBL;
      if (ioctl(sockfd, SIOCSARP, (caddr_t)&arpreq) < 0) {
  	error("ioctl(SIOCSARP): %m");
  	return 0;
      }
  
      proxy_arp_addr = hisaddr;
      return 1;
  }
  
  /*
   * cifproxyarp - Delete the proxy ARP entry for the peer.
   */
  int
  cifproxyarp(unit, hisaddr)
      int unit;
      u_int32_t hisaddr;
  {
      struct arpreq arpreq;
  
      BZERO(&arpreq, sizeof(arpreq));
      SET_SA_FAMILY(arpreq.arp_pa, AF_INET);
      ((struct sockaddr_in *) &arpreq.arp_pa)->sin_addr.s_addr = hisaddr;
      if (ioctl(sockfd, SIOCDARP, (caddr_t)&arpreq) < 0) {
  	warn("ioctl(SIOCDARP): %m");
  	return 0;
      }
      proxy_arp_addr = 0;
      return 1;
  }
  
  /*
   * get_ether_addr - get the hardware address of an interface on the
   * the same subnet as ipaddr.
   */
  #define MAX_IFS		32
  
  int
  get_ether_addr(ipaddr, hwaddr)
      u_int32_t ipaddr;
      struct sockaddr *hwaddr;
  {
      struct ifreq *ifr, *ifend, *ifp;
      u_int32_t ina, mask;
      struct ether_addr dla;
      struct ifreq ifreq;
      struct ifconf ifc;
      struct ifreq ifs[MAX_IFS];
      struct hostent *hostent;
  
      ifc.ifc_len = sizeof(ifs);
      ifc.ifc_req = ifs;
      if (ioctl(sockfd, SIOCGIFCONF, &ifc) < 0) {
  	error("ioctl(SIOCGIFCONF): %m");
  	return 0;
      }
  
      /*
       * Scan through looking for an interface with an Internet
       * address on the same subnet as `ipaddr'.
       */
      ifend = (struct ifreq *) (ifc.ifc_buf + ifc.ifc_len);
      for (ifr = ifc.ifc_req; ifr < ifend; ifr = (struct ifreq *)
  		((char *)&ifr->ifr_addr + sizeof(struct sockaddr))) {
  	if (ifr->ifr_addr.sa_family == AF_INET) {
  	    ina = ((struct sockaddr_in *) &ifr->ifr_addr)->sin_addr.s_addr;
  	    strlcpy(ifreq.ifr_name, ifr->ifr_name, sizeof(ifreq.ifr_name));
  	    /*
  	     * Check that the interface is up, and not point-to-point
  	     * or loopback.
  	     */
  	    if (ioctl(sockfd, SIOCGIFFLAGS, &ifreq) < 0)
  		continue;
  	    if ((ifreq.ifr_flags &
  		 (IFF_UP|IFF_BROADCAST|IFF_POINTOPOINT|IFF_LOOPBACK|IFF_NOARP))
  		 != (IFF_UP|IFF_BROADCAST))
  		continue;
  	    /*
  	     * Get its netmask and check that it's on the right subnet.
  	     */
  	    if (ioctl(sockfd, SIOCGIFNETMASK, &ifreq) < 0)
  		continue;
  	    mask = ((struct sockaddr_in*)&ifreq.ifr_addr)->sin_addr.s_addr;
  	    if ((ipaddr & mask) != (ina & mask))
  		continue;
  
  	    break;
  	}
      }
  
      if (ifr >= ifend)
  	return 0;
      info("found interface %s for proxy arp", ifr->ifr_name);
  
      /*
       * Get the hostname and look for an entry using the ethers database.
       * Under NeXTStep this is the best we can do for now.
       */
      if ((hostent = gethostbyaddr((char*)&ina, sizeof(ina), AF_INET)) == NULL)
  	return 0;
  
      if (ether_by_host(hostent->h_name, &dla)) {
  	info("Add entry for %s in /etc/ethers", hostent->h_name);
  	return 0;	/* it's not there */
      }
      hwaddr->sa_family = AF_UNSPEC;
      BCOPY(&dla, hwaddr->sa_data, sizeof(dla));
      return 1;
  }
  
  static int
  ether_by_host(hostname, etherptr)
      char *hostname;
      struct ether_addr *etherptr;
  {
      struct ether_addr *thisptr;
      void *conn;
      ni_id root;
      ni_namelist val;
      char path[256];
  
      if (!ether_hostton(hostname, etherptr))
  	return 0;
      /*
       * We shall now try and
       * find the address in the
       * top domain of netinfo.
       */
      slprintf(path, sizeof(path), "/machines/%s", hostname);
  
      if (ni_open((void *)0, "/", &conn)
       || ni_root(conn, &root)
       || ni_pathsearch(conn, &root, path)
       || ni_lookupprop(conn, &root, "en_address", &val))
  	return 1;
  
      /*
       * Now we can convert the returned string into an ethernet address.
       */
      strlcpy(path, val.ni_namelist_val[0], sizeof(path));
      ni_free(conn);
      if ((thisptr = (struct ether_addr*)ether_aton(path)) == NULL)
  	return 1;
      BCOPY(thisptr, etherptr, sizeof(struct ether_addr));
      return 0;
  }
  
  
  
  /*
   * Return user specified netmask, modified by any mask we might determine
   * for address `addr' (in network byte order).
   * Here we scan through the system's list of interfaces, looking for
   * any non-point-to-point interfaces which might appear to be on the same
   * network as `addr'.  If we find any, we OR in their netmask to the
   * user-specified netmask.
   */
  u_int32_t
  GetMask(addr)
      u_int32_t addr;
  {
      u_int32_t mask, nmask, ina;
      struct ifreq *ifr, *ifend, ifreq;
      struct ifconf ifc;
      struct ifreq ifs[MAX_IFS];
  
      addr = ntohl(addr);
      if (IN_CLASSA(addr))	/* determine network mask for address class */
  	nmask = IN_CLASSA_NET;
      else if (IN_CLASSB(addr))
  	nmask = IN_CLASSB_NET;
      else
  	nmask = IN_CLASSC_NET;
      /* class D nets are disallowed by bad_ip_adrs */
      mask = netmask | htonl(nmask);
  
      /*
       * Scan through the system's network interfaces.
       */
      ifc.ifc_len = sizeof(ifs);
      ifc.ifc_req = ifs;
      if (ioctl(sockfd, SIOCGIFCONF, &ifc) < 0) {
  	warn("ioctl(SIOCGIFCONF): %m");
  	return mask;
      }
      ifend = (struct ifreq *) (ifc.ifc_buf + ifc.ifc_len);
      for (ifr = ifc.ifc_req; ifr < ifend; ifr = (struct ifreq *)
  	 	((char *)&ifr->ifr_addr + sizeof(struct sockaddr))) {
  	/*
  	 * Check the interface's internet address.
  	 */
  	if (ifr->ifr_addr.sa_family != AF_INET)
  	    continue;
  	ina = ((struct sockaddr_in *) &ifr->ifr_addr)->sin_addr.s_addr;
  	if ((ntohl(ina) & nmask) != (addr & nmask))
  	    continue;
  	/*
  	 * Check that the interface is up, and not point-to-point or loopback.
  	 */
  	strlcpy(ifreq.ifr_name, ifr->ifr_name, sizeof(ifreq.ifr_name));
  	if (ioctl(sockfd, SIOCGIFFLAGS, &ifreq) < 0)
  	    continue;
  	if ((ifreq.ifr_flags & (IFF_UP|IFF_POINTOPOINT|IFF_LOOPBACK))
  	    != IFF_UP)
  	    continue;
  	/*
  	 * Get its netmask and OR it into our mask.
  	 */
  	if (ioctl(sockfd, SIOCGIFNETMASK, &ifreq) < 0)
  	    continue;
  	mask |= ((struct sockaddr_in *)&ifreq.ifr_addr)->sin_addr.s_addr;
      }
  
      return mask;
  }
  
  /*
   * have_route_to - determine if the system has any route to
   * a given IP address.
   * For demand mode to work properly, we have to ignore routes
   * through our own interface.
   */
  int have_route_to(u_int32_t addr)
  {
      return -1;
  }
  
  #if 0
  /*
   * daemon - Detach us from the terminal session.
   */
  int
  daemon(nochdir, noclose)
      int nochdir, noclose;
  {
      int pid;
  
      if ((pid = fork()) < 0)
  	return -1;
      if (pid != 0)
  	exit(0);		/* parent dies */
      (void)setsid();
      if (!nochdir)
  	chdir("/");
      if (!noclose) {
  	fclose(stdin);		/* don't need stdin, stdout, stderr */
  	fclose(stdout);
  	fclose(stderr);
      }
      return 0;
  }
  #endif
  
  char *
  strdup(s)
      const char *s;
  {
      char *d = malloc(strlen(s) + 1);
  
      if (d) strcpy(d, s);
      return d;
  }
  
  /*
   * This logwtmp() implementation is subject to the following copyright:
   *
   * Copyright (c) 1988 The Regents of the University of California.
   * 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 the University of California, Berkeley.  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.
   */
  
  #define WTMPFILE        "/usr/adm/wtmp"
  
  void
  logwtmp(line, name, host)
      const char *line, *name, *host;
  {
      int fd;
      struct stat buf;
      struct utmp ut;
  
      if ((fd = open(WTMPFILE, O_WRONLY|O_APPEND, 0)) < 0)
  	return;
      if (!fstat(fd, &buf)) {
  	strncpy(ut.ut_line, line, sizeof(ut.ut_line));
  	strncpy(ut.ut_name, name, sizeof(ut.ut_name));
  	strncpy(ut.ut_host, host, sizeof(ut.ut_host));
  	(void)time(&ut.ut_time);
  	if (write(fd, (char *)&ut, sizeof(struct utmp)) != sizeof(struct utmp))
  	    (void)ftruncate(fd, buf.st_size);
      }
      close(fd);
  }
  
  #if 0
  /*
   * Routines for locking and unlocking the serial device, moved here
   * from chat.c.
   */
  
  #define LOCK_PREFIX	"/usr/spool/uucp/LCK/LCK.."
  
  static char *lock_file;
  
  /*
   * lock - create a lock file for the named device
   */
  int
  lock(dev)
      char *dev;
  {
      int fd, pid, n;
      char *p;
      size_t l;
  
      if ((p = strrchr(dev, '/')) != NULL)
  	dev = p + 1;
      l = strlen(LOCK_PREFIX) + strlen(dev) + 1;
      lock_file = malloc(l);
      if (lock_file == NULL)
  	novm("lock file name");
      slprintf(lock_file, l, "%s%s", LOCK_PREFIX, dev);
  
      while ((fd = open(lock_file, O_EXCL | O_CREAT | O_RDWR, 0644)) < 0) {
  	if (errno == EEXIST
  	    && (fd = open(lock_file, O_RDONLY, 0)) >= 0) {
  	    /* Read the lock file to find out who has the device locked */
  	    n = read(fd, &pid, sizeof(pid));
  	    if (n <= 0) {
  		error("Can't read pid from lock file %s", lock_file);
  		close(fd);
  	    } else {
  		if (kill(pid, 0) == -1 && errno == ESRCH) {
  		    /* pid no longer exists - remove the lock file */
  		    if (unlink(lock_file) == 0) {
  			close(fd);
  			notice("Removed stale lock on %s (pid %d)",
  			       dev, pid);
  			continue;
  		    } else
  			warn("Couldn't remove stale lock on %s", dev);
  		} else
  		    notice("Device %s is locked by pid %d",
  			   dev, pid);
  	    }
  	    close(fd);
  	} else
  	    error("Can't create lock file %s: %m", lock_file);
  	free(lock_file);
  	lock_file = NULL;
  	return -1;
      }
  
      pid = getpid();
      write(fd, &pid, sizeof pid);
  
      close(fd);
      return 0;
  }
  
  /*
   * unlock - remove our lockfile
   */
  void
  unlock()
  {
      if (lock_file) {
  	unlink(lock_file);
  	free(lock_file);
  	lock_file = NULL;
      }
  }
  #endif
  
  #if defined(i386) && defined(HAS_BROKEN_IOCTL)
  int
  ioctl(fd, cmd, c)
      int fd, cmd;
      caddr_t c;
  {
  #undef	ioctl
      int ret;
  
  #ifdef DEBUGIOCTL
      int serrno;
      u_char let, code, size;
  
      size = (cmd >> 16) & IOCPARM_MASK;
      let = (cmd >> 8);
      code = cmd;
  
      if (let == 't' && (75 <= code && code <= 90))
      info("ioctl(%d, 0x%x ('%c', %d, %d), 0x%x)\n", fd, cmd,
  	   let, code, size, c);
  #endif
  
      ret = ioctl(fd, cmd, c);
  
  #ifdef DEBUGIOCTL
      serrno = errno;
      if (ret == -1)
  	info("ioctl('%c', %d, %d) errno = %d (%m)\n",
  		let, code, size, errno);
      if (let == 't' && (75 <= code && code <= 90) && (cmd & IOC_OUT)) {
  	int i, len = ((cmd >> 16) & IOCPARM_MASK);
  	for (i = 0; i < len / 4; ++i)
  		info("word[%d] @ 0x%06x = 0x%x\n",
  		       i, &((int *) c)[i],((int *)c)[i]);
      }
      errno = serrno;
  #endif
  
      if (ret == -1 && errno == EPERM)
  	errno = ret = 0;
      return ret;
  }
  #endif	/* HAS_BROKEN_IOCTL */
  
  
  #if defined(FIXSIGS) && (defined (hppa) || defined(sparc))
  
  /*
   * These redefinitions of Posix functions are necessary
   * because HPPA systems have an OS bug that causes 
   * sigaction to core dump:
   *
   * AlainF 9-Nov-1994	HACK FOR HP-PA/NEXTSTEP
   *			sigaction(3) seems broken in the HP-PA NeXTSTEP 3.2
   *			Posix lib. This causes pppd to SIGBUS at the expiration
   *			of the first timeout (_sigtramp seems to invoke
   *			the SIGALRM handler at an unreasonably low address).
   *			All calls so sigaction(3) have been changed to calls
   *			to sigvec(2) and sigprocmask(SIG_BLOCK,...) to
   *			sigblock(2).
   *			This is kind of a hack, especially since there are
   *			other routines of the Posix lib still used, but
   *			it worked for me.
   *
   * Dave Hess <David-Hess@net.tamu.edu> noted that 3.3 Sparc seems to
   * have the same bug.  Thus this fix has been enabled for SPARC also.
   *
   *
   */
  
  int sigemptyset(sigset_t *mask)
  {
    *mask = 0;
  }
  
  sigaddset(sigset_t *mask, int which_sig)
  {
    *mask |= sigmask(which_sig);
  }
  
  
  int sigaction(int sig, const struct sigaction *act, struct sigaction *oact)
  {
     struct sigvec sv;
     static int in = 0;
  
     sv.sv_handler = act->sa_handler;
     sv.sv_mask = act->sa_mask;
     sv.sv_flags = 0;
  
     if (!in)
       {
         in = 1;
         warn("PPPD: Inside modified HP and SPARC sigaction\n");
       }
  
     return sigvec(sig, &sv, NULL);
  }
  
  #endif
  
  
  /*
   * Code following is added for 2.3 compatibility
   */
  
  /*
   * get_idle_time - return how long the link has been idle.
   */
  int
  get_idle_time(u, ip)
      int u;
      struct ppp_idle *ip;
  {
    return (ioctl(ttyfd, PPPIOCGIDLE, ip) >= 0); 
  }
  
  /*
   * get_ppp_stats - return statistics for the link.
   */
  int
  get_ppp_stats(u, stats)
      int u;
      struct pppd_stats *stats;
  {
      struct ifpppstatsreq req;
  
      memset (&req, 0, sizeof (req));
      strlcpy(req.ifr_name, interface, sizeof(req.ifr_name));
      if (ioctl(sockfd, SIOCGPPPSTATS, &req) < 0) {
  	error("Couldn't get PPP statistics: %m");
  	return 0;
      }
      stats->bytes_in = req.stats.p.ppp_ibytes;
      stats->bytes_out = req.stats.p.ppp_obytes;
      return 1;
  }
  
  
  /*
   * get_loop_output - read characters from the loopback, form them
   * into frames, and detect when we want to bring the real link up.
   * Return value is 1 if we need to bring up the link, 0 otherwise.
   */
  int
  get_loop_output()
  {
  
  #if 0
      int rv = 0;
      int n;
  
      while ((n = read(loop_master, inbuf, sizeof(inbuf))) >= 0) {
  	if (loop_chars(inbuf, n))
  	    rv = 1;
      }
  
      if (n == 0)
  	fatal("eof on loopback");
      if (errno != EWOULDBLOCK)
  	fatal("read from loopback: %m");
  
      return rv;
  #endif
  
      return 0;
  }
  
  /*
   * sifnpmode - Set the mode for handling packets for a given NP.
   */
  int
  sifnpmode(u, proto, mode)
      int u;
      int proto;
      enum NPmode mode;
  {
      struct npioctl npi;
  
      npi.protocol = proto;
      npi.mode = mode;
      if (ioctl(ttyfd, PPPIOCSNPMODE, &npi) < 0) {
  	error("ioctl(set NP %d mode to %d): %m", proto, mode);
  	return 0;
      }
      return 1;
  }
  
  
  /*
   * open_ppp_loopback - open the device we use for getting
   * packets in demand mode, and connect it to a ppp interface.
   * Here we use a pty.
   */
  int
  open_ppp_loopback()
  {
  
  #if 0
      int flags;
      struct termios tios;
      int pppdisc = PPPDISC;
  
      fatal("open_ppp_loopback called!");
  
      if (openpty(&loop_master, &loop_slave, loop_name, NULL, NULL) < 0)
  	fatal("No free pty for loopback");
      SYSDEBUG(("using %s for loopback", loop_name));
  
      if (tcgetattr(loop_slave, &tios) == 0) {
  	tios.c_cflag &= ~(CSIZE | CSTOPB | PARENB);
  	tios.c_cflag |= CS8 | CREAD;
  	tios.c_iflag = IGNPAR;
  	tios.c_oflag = 0;
  	tios.c_lflag = 0;
  	if (tcsetattr(loop_slave, TCSAFLUSH, &tios) < 0)
  	    warn("couldn't set attributes on loopback: %m");
      }
  
      if ((flags = fcntl(loop_master, F_GETFL)) != -1) 
  	if (fcntl(loop_master, F_SETFL, flags | O_NONBLOCK) == -1)
  	    warn("couldn't set loopback to nonblock: %m");
  
      ttyfd = loop_slave;
      if (ioctl(ttyfd, TIOCSETD, &pppdisc) < 0)
  	fatal("ioctl(TIOCSETD): %m");
  
      /*
       * Find out which interface we were given.
       */
      if (ioctl(ttyfd, PPPIOCGUNIT, &ifunit) < 0)
  	fatal("ioctl(PPPIOCGUNIT): %m");
  
      /*
       * Enable debug in the driver if requested.
       */
      if (kdebugflag) {
  	if (ioctl(ttyfd, PPPIOCGFLAGS, (caddr_t) &flags) < 0) {
  	    warn("ioctl (PPPIOCGFLAGS): %m");
  	} else {
  	    flags |= (kdebugflag & 0xFF) * SC_DEBUG;
  	    if (ioctl(ttyfd, PPPIOCSFLAGS, (caddr_t) &flags) < 0)
  		warn("ioctl(PPPIOCSFLAGS): %m");
  	}
      }
  
      return loop_master;
  #endif
  
  }
  
  /*
   * restore_loop - reattach the ppp unit to the loopback.
   */
  void
  restore_loop()
  {
      int x;
  
      /*
       * Transfer the ppp interface back to the loopback.
       */
      if (ioctl(ttyfd, PPPIOCXFERUNIT, 0) < 0)
  	fatal("ioctl(transfer ppp unit): %m");
      x = PPPDISC;
      if (ioctl(loop_slave, TIOCSETD, &x) < 0)
  	fatal("ioctl(TIOCSETD): %m");
  
      /*
       * Check that we got the same unit again.
       */
      if (ioctl(loop_slave, PPPIOCGUNIT, &x) < 0)
  	fatal("ioctl(PPPIOCGUNIT): %m");
      if (x != ifunit)
  	fatal("transfer_ppp failed: wanted unit %d, got %d",
  	      ifunit, x);
      ttyfd = loop_slave;
  }
  
  
  /*
   * Use the hostid as part of the random number seed.
   */
  int
  get_host_seed()
  {
      return gethostid();
  }
  
  
  /*
   * sys_check_options - check the options that the user specified
   */
  int
  sys_check_options()
  {
    /*
     * We don't support demand dialing yet.
     */
    if (demand)
      {
        option_error("PPP-2.3 for NeXTSTEP does not yet support demand dialing");
        return 0;
      }
    return 1;
  }
  
  
  /*
   * sys_close - Clean up in a child process before execing.
   */
  void
  sys_close()
  {
      close(sockfd);
      if (loop_slave >= 0) {
  	close(loop_slave);
  	close(loop_master);
      }
      closelog();
  }
  
  #if 0
  /*
   * wait_loop_output - wait until there is data available on the
   * loopback, for the length of time specified by *timo (indefinite
   * if timo is NULL).
   */
  void wait_loop_output(timo)
      struct timeval *timo;
  {
      fd_set ready;
      int n;
  
      FD_ZERO(&ready);
      FD_SET(loop_master, &ready);
      n = select(loop_master + 1, &ready, NULL, &ready, timo);
      if (n < 0 && errno != EINTR)
  	fatal("select: %m");
  }
  
  /*
   * wait_time - wait for a given length of time or until a
   * signal is received.
   */
  void wait_time(timo)
      struct timeval *timo;
  {
      int n;
  
      n = select(0, NULL, NULL, NULL, timo);
      if (n < 0 && errno != EINTR)
  	fatal("select: %m");
  }
  #endif
  