fix the bug in non-demand mode that I inadvertently introduced

[mpls-ppp.git] / pppd / sys-linux.c

/*
 * sys-linux.c - System-dependent procedures for setting up
 * PPP interfaces on Linux systems
 *
 * 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.
 */

#include <sys/ioctl.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/time.h>
#include <sys/errno.h>
#include <sys/file.h>
#include <sys/stat.h>
#include <sys/utsname.h>
#include <sys/sysmacros.h>

#include <stdio.h>
#include <stdlib.h>
#include <syslog.h>
#include <string.h>
#include <time.h>
#include <memory.h>
#include <utmp.h>
#include <mntent.h>
#include <signal.h>
#include <fcntl.h>
#include <ctype.h>
#include <termios.h>
#include <unistd.h>

/* This is in netdevice.h. However, this compile will fail miserably if
   you attempt to include netdevice.h because it has so many references
   to __memcpy functions which it should not attempt to do. So, since I
   really don't use it, but it must be defined, define it now. */

#ifndef MAX_ADDR_LEN
#define MAX_ADDR_LEN 7
#endif

#if __GLIBC__ >= 2
#include <asm/types.h>          /* glibc 2 conflicts with linux/types.h */
#include <net/if.h>
#include <net/if_arp.h>
#include <net/route.h>
#include <netinet/if_ether.h>
#else
#include <linux/types.h>
#include <linux/if.h>
#include <linux/if_arp.h>
#include <linux/route.h>
#include <linux/if_ether.h>
#endif
#include <netinet/in.h>
#include <arpa/inet.h>

#include <linux/ppp_defs.h>
#include <linux/if_ppp.h>

#include "pppd.h"
#include "fsm.h"
#include "ipcp.h"
#include "patchlevel.h"

#ifdef IPX_CHANGE
#include "ipxcp.h"
#if __GLIBC__ >= 2 && \
    !(defined(__powerpc__) && __GLIBC__ == 2 && __GLIBC_MINOR__ == 0)
#include <netipx/ipx.h>
#else
#include <linux/ipx.h>
#endif
#endif /* IPX_CHANGE */

#ifdef LOCKLIB
#include <sys/locks.h>
#endif

#ifdef INET6
#ifndef _LINUX_IN6_H
/*
 *    This is in linux/include/net/ipv6.h.
 */

struct in6_ifreq {
    struct in6_addr ifr6_addr;
    __u32 ifr6_prefixlen;
    unsigned int ifr6_ifindex;
};
#endif

#define IN6_LLADDR_FROM_EUI64(sin6, eui64) do {                 \
        memset(&sin6.s6_addr, 0, sizeof(struct in6_addr));      \
        sin6.s6_addr16[0] = htons(0xfe80);                      \
        eui64_copy(eui64, sin6.s6_addr32[2]);                   \
        } while (0)

#endif /* INET6 */

/* We can get an EIO error on an ioctl if the modem has hung up */
#define ok_error(num) ((num)==EIO)

static int tty_disc = N_TTY;    /* The TTY discipline */
static int ppp_disc = N_PPP;    /* The PPP discpline */
static int initfdflags = -1;    /* Initial file descriptor flags for fd */
static int ppp_fd = -1;         /* fd which is set to PPP discipline */
static int sock_fd = -1;        /* socket for doing interface ioctls */
static int slave_fd = -1;
static int master_fd = -1;
#ifdef INET6
static int sock6_fd = -1;
#endif /* INET6 */
static int ppp_dev_fd = -1;     /* fd for /dev/ppp (new style driver) */
static int chindex;             /* channel index (new style driver) */

static fd_set in_fds;           /* set of fds that wait_input waits for */
static int max_in_fd;           /* highest fd set in in_fds */

static int has_proxy_arp       = 0;
static int driver_version      = 0;
static int driver_modification = 0;
static int driver_patch        = 0;
static int driver_is_old       = 0;
static int restore_term        = 0;     /* 1 => we've munged the terminal */
static struct termios inittermios;      /* Initial TTY termios */

static int new_style_driver = 0;

static char loop_name[20];
static unsigned char inbuf[512]; /* buffer for chars read from loopback */

static int      if_is_up;       /* Interface has been marked up */
static u_int32_t default_route_gateway; /* Gateway for default route added */
static u_int32_t proxy_arp_addr;        /* Addr for proxy arp entry added */
static char proxy_arp_dev[16];          /* Device for proxy arp entry */
static u_int32_t our_old_addr;          /* for detecting address changes */
static int      dynaddr_set;            /* 1 if ip_dynaddr set */
static int      looped;                 /* 1 if using loop */
static int      link_mtu;               /* mtu for the link (not bundle) */

static struct utsname utsname;  /* for the kernel version */
static int kernel_version;
#define KVERSION(j,n,p) ((j)*1000000 + (n)*1000 + (p))

#define MAX_IFS         100

#define FLAGS_GOOD (IFF_UP          | IFF_BROADCAST)
#define FLAGS_MASK (IFF_UP          | IFF_BROADCAST | \
                    IFF_POINTOPOINT | IFF_LOOPBACK  | IFF_NOARP)

#define SIN_ADDR(x)     (((struct sockaddr_in *) (&(x)))->sin_addr.s_addr)

/* Prototypes for procedures local to this file. */
static int get_flags (int fd);
static void set_flags (int fd, int flags);
static int translate_speed (int bps);
static int baud_rate_of (int speed);
static void close_route_table (void);
static int open_route_table (void);
static int read_route_table (struct rtentry *rt);
static int defaultroute_exists (struct rtentry *rt);
static int get_ether_addr (u_int32_t ipaddr, struct sockaddr *hwaddr,
                           char *name, int namelen);
static void decode_version (char *buf, int *version, int *mod, int *patch);
static int set_kdebugflag(int level);
static int ppp_registered(void);
static int make_ppp_unit(void);

extern u_char   inpacket_buf[]; /* borrowed from main.c */

/*
 * SET_SA_FAMILY - set the sa_family field of a struct sockaddr,
 * if it exists.
 */

#define SET_SA_FAMILY(addr, family)                     \
    memset ((char *) &(addr), '\0', sizeof(addr));      \
    addr.sa_family = (family);

/*
 * Determine if the PPP connection should still be present.
 */

extern int hungup;

/* new_fd is the fd of a tty */
static void set_ppp_fd (int new_fd)
{
        SYSDEBUG ((LOG_DEBUG, "setting ppp_fd to %d\n", new_fd));
        ppp_fd = new_fd;
        if (!new_style_driver)
                ppp_dev_fd = new_fd;
}

static int still_ppp(void)
{
        if (new_style_driver)
                return !hungup && ppp_fd >= 0;
        if (!hungup || ppp_fd == slave_fd)
                return 1;
        if (slave_fd >= 0) {
                set_ppp_fd(slave_fd);
                return 1;
        }
        return 0;
}

/********************************************************************
 *
 * Functions to read and set the flags value in the device driver
 */

static int get_flags (int fd)
{    
    int flags;

    if (ioctl(fd, PPPIOCGFLAGS, (caddr_t) &flags) < 0) {
        if ( ok_error (errno) )
            flags = 0;
        else
            fatal("ioctl(PPPIOCGFLAGS): %m");
    }

    SYSDEBUG ((LOG_DEBUG, "get flags = %x\n", flags));
    return flags;
}

/********************************************************************/

static void set_flags (int fd, int flags)
{    
    SYSDEBUG ((LOG_DEBUG, "set flags = %x\n", flags));

    if (ioctl(fd, PPPIOCSFLAGS, (caddr_t) &flags) < 0) {
        if (! ok_error (errno) )
            fatal("ioctl(PPPIOCSFLAGS, %x): %m", flags, errno);
    }
}

/********************************************************************
 *
 * sys_init - System-dependent initialization.
 */

void sys_init(void)
{
    int flags;

    openlog("pppd", LOG_PID | LOG_NDELAY, LOG_PPP);
    setlogmask(LOG_UPTO(LOG_INFO));
    if (debug)
        setlogmask(LOG_UPTO(LOG_DEBUG));

    if (new_style_driver) {
        ppp_dev_fd = open("/dev/ppp", O_RDWR);
        if (ppp_dev_fd < 0)
            fatal("Couldn't open /dev/ppp: %m");
        flags = fcntl(ppp_dev_fd, F_GETFL);
        if (flags == -1
            || fcntl(ppp_dev_fd, F_SETFL, flags | O_NONBLOCK) == -1)
            warn("Couldn't set /dev/ppp to nonblock: %m");
    }

    /* Get an internet socket for doing socket ioctls. */
    sock_fd = socket(AF_INET, SOCK_DGRAM, 0);
    if (sock_fd < 0)
        fatal("Couldn't create IP socket: %m(%d)", errno);

#ifdef INET6
    sock6_fd = socket(AF_INET6, SOCK_DGRAM, 0);
    if (sock6_fd < 0)
        fatal("Couldn't create IPv6 socket: %m(%d)", errno);
#endif

    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 shouldn't call die() because it's called from die().
 */

void sys_cleanup(void)
{
/*
 * Take down the device
 */
    if (if_is_up) {
        if_is_up = 0;
        sifdown(0);
    }
/*
 * Delete any routes through the device.
 */
    if (default_route_gateway != 0)
        cifdefaultroute(0, 0, default_route_gateway);

    if (has_proxy_arp)
        cifproxyarp(0, proxy_arp_addr);
}

/********************************************************************
 *
 * sys_close - Clean up in a child process before execing.
 */
void
sys_close(void)
{
    if (new_style_driver)
        close(ppp_dev_fd);
    if (sock_fd >= 0)
        close(sock_fd);
    if (slave_fd >= 0)
        close(slave_fd);
    if (master_fd >= 0)
        close(master_fd);
    closelog();
}

/********************************************************************
 *
 * set_kdebugflag - Define the debugging level for the kernel
 */

static int set_kdebugflag (int requested_level)
{
    if (new_style_driver && ifunit < 0)
        return 1;
    if (ioctl(ppp_dev_fd, PPPIOCSDEBUG, &requested_level) < 0) {
        if ( ! ok_error (errno) )
            error("ioctl(PPPIOCSDEBUG): %m");
        return (0);
    }
    SYSDEBUG ((LOG_INFO, "set kernel debugging level to %d",
                requested_level));
    return (1);
}

/********************************************************************
 *
 * establish_ppp - Turn the serial port into a ppp interface.
 */

int establish_ppp (int tty_fd)
{
    int x;
    int fd = -1;

/*
 * Ensure that the tty device is in exclusive mode.
 */
    if (ioctl(tty_fd, TIOCEXCL, 0) < 0) {
        if ( ! ok_error ( errno ))
            warn("Couldn't make tty exclusive: %m");
    }
/*
 * Demand mode - prime the old ppp device to relinquish the unit.
 */
    if (!new_style_driver && looped
        && ioctl(slave_fd, PPPIOCXFERUNIT, 0) < 0) {
        error("ioctl(transfer ppp unit): %m");
        return -1;
    }
/*
 * Set the current tty to the PPP discpline
 */

#ifndef N_SYNC_PPP
#define N_SYNC_PPP 14
#endif
    ppp_disc = (new_style_driver && sync_serial)? N_SYNC_PPP: N_PPP;
    if (ioctl(tty_fd, TIOCSETD, &ppp_disc) < 0) {
        if ( ! ok_error (errno) ) {
            error("Couldn't set tty to PPP discipline: %m");
            return -1;
        }
    }

    if (new_style_driver) {
        /* Open another instance of /dev/ppp and connect the channel to it */
        int flags;

        if (ioctl(tty_fd, PPPIOCGCHAN, &chindex) == -1) {
            error("Couldn't get channel number: %m");
            goto err;
        }
        dbglog("using channel %d", chindex);
        fd = open("/dev/ppp", O_RDWR);
        if (fd < 0) {
            error("Couldn't reopen /dev/ppp: %m");
            goto err;
        }
        if (ioctl(fd, PPPIOCATTCHAN, &chindex) < 0) {
            error("Couldn't attach to channel %d: %m", chindex);
            goto err_close;
        }
        flags = fcntl(fd, F_GETFL);
        if (flags == -1 || fcntl(fd, F_SETFL, flags | O_NONBLOCK) == -1)
            warn("Couldn't set /dev/ppp (channel) to nonblock: %m");
        set_ppp_fd(fd);

        if (!looped)
            ifunit = -1;
        if (!looped && !multilink) {
            /*
             * Create a new PPP unit.
             */
            if (make_ppp_unit() < 0)
                goto err_close;
        }

        if (looped)
            set_flags(ppp_dev_fd, get_flags(ppp_dev_fd) & ~SC_LOOP_TRAFFIC);

        if (!multilink) {
            add_fd(ppp_dev_fd);
            if (ioctl(fd, PPPIOCCONNECT, &ifunit) < 0) {
                error("Couldn't attach to PPP unit %d: %m", ifunit);
                goto err_close;
            }
        }

    } else {
        /*
         * Old-style driver: find out which interface we were given.
         */
        set_ppp_fd (tty_fd);
        if (ioctl(tty_fd, PPPIOCGUNIT, &x) < 0) {       
            if ( ! ok_error (errno))
                fatal("ioctl(PPPIOCGUNIT): %m(%d)", errno);
        }
        /* Check that we got the same unit again. */
        if (looped && x != ifunit)
            fatal("transfer_ppp failed: wanted unit %d, got %d", ifunit, x);
        ifunit = x;

        /*
         * Fetch the initial file flags and reset blocking mode on the file.
         */
        initfdflags = fcntl(tty_fd, F_GETFL);
        if (initfdflags == -1 ||
            fcntl(tty_fd, F_SETFL, initfdflags | O_NONBLOCK) == -1) {
            if ( ! ok_error (errno))
                warn("Couldn't set device to non-blocking mode: %m");
        }
    }

    looped = 0;

    /*
     * Enable debug in the driver if requested.
     */
    if (!looped)
        set_kdebugflag (kdebugflag);

    set_flags(ppp_fd, get_flags(ppp_fd) & ~(SC_RCV_B7_0 | SC_RCV_B7_1 |
                                            SC_RCV_EVNP | SC_RCV_ODDP));

    SYSDEBUG ((LOG_NOTICE, "Using version %d.%d.%d of PPP driver",
            driver_version, driver_modification, driver_patch));

    return ppp_fd;

 err_close:
    close(fd);
 err:
    if (ioctl(tty_fd, TIOCSETD, &tty_disc) < 0 && !ok_error(errno))
        warn("Couldn't reset tty to normal line discipline: %m");
    return -1;
}

/********************************************************************
 *
 * disestablish_ppp - Restore the serial port to normal operation.
 * This shouldn't call die() because it's called from die().
 */

void disestablish_ppp(int tty_fd)
{
    if (!hungup) {
/*
 * Flush the tty output buffer so that the TIOCSETD doesn't hang.
 */
        if (tcflush(tty_fd, TCIOFLUSH) < 0)
            warn("tcflush failed: %m");
/*
 * Restore the previous line discipline
 */
        if (ioctl(tty_fd, TIOCSETD, &tty_disc) < 0) {
            if ( ! ok_error (errno))
                error("ioctl(TIOCSETD, N_TTY): %m");
        }
        
        if (ioctl(tty_fd, TIOCNXCL, 0) < 0) {
            if ( ! ok_error (errno))
                warn("ioctl(TIOCNXCL): %m(%d)", errno);
        }

        /* Reset non-blocking mode on fd. */
        if (initfdflags != -1 && fcntl(tty_fd, F_SETFL, initfdflags) < 0) {
            if ( ! ok_error (errno))
                warn("Couldn't restore device fd flags: %m");
        }
    }
    initfdflags = -1;

    if (new_style_driver) {
        close(ppp_fd);
        ppp_fd = -1;
        if (!looped && ifunit >= 0 && ioctl(ppp_dev_fd, PPPIOCDETACH) < 0)
            error("Couldn't release PPP unit: %m");
        if (!multilink)
            remove_fd(ppp_dev_fd);
    }
}

/*
 * make_ppp_unit - make a new ppp unit for ppp_dev_fd.
 * Assumes new_style_driver.
 */
static int make_ppp_unit()
{
        int x;

        ifunit = req_unit;
        x = ioctl(ppp_dev_fd, PPPIOCNEWUNIT, &ifunit);
        if (x < 0 && req_unit >= 0 && errno == EEXIST) {
                warn("Couldn't allocate PPP unit %d as it is already in use");
                ifunit = -1;
                x = ioctl(ppp_dev_fd, PPPIOCNEWUNIT, &ifunit);
        }
        if (x < 0)
                error("Couldn't create new ppp unit: %m");
        return x;
}

/*
 * cfg_bundle - configure the existing bundle.
 * Used in demand mode.
 */
void cfg_bundle(int mrru, int mtru, int rssn, int tssn)
{
        int flags;
        struct ifreq ifr;

        if (!new_style_driver)
                return;

        /* set the mrru, mtu and flags */
        if (ioctl(ppp_dev_fd, PPPIOCSMRRU, &mrru) < 0)
                error("Couldn't set MRRU: %m");
        flags = get_flags(ppp_dev_fd);
        flags &= ~(SC_MP_SHORTSEQ | SC_MP_XSHORTSEQ);
        flags |= (rssn? SC_MP_SHORTSEQ: 0) | (tssn? SC_MP_XSHORTSEQ: 0);

        if (mtru > 0 && mtru != link_mtu) {
                memset(&ifr, 0, sizeof(ifr));
                slprintf(ifr.ifr_name, sizeof(ifr.ifr_name), "ppp%d", ifunit);
                ifr.ifr_mtu = mtru;
                if (ioctl(sock_fd, SIOCSIFMTU, &ifr) < 0)
                        error("Couldn't set interface MTU: %m");
                flags |= SC_MULTILINK;
        }

        set_flags(ppp_dev_fd, flags);

        /* connect up the channel */
        if (ioctl(ppp_fd, PPPIOCCONNECT, &ifunit) < 0)
                fatal("Couldn't attach to PPP unit %d: %m", ifunit);
        add_fd(ppp_dev_fd);
}

/*
 * make_new_bundle - create a new PPP unit (i.e. a bundle)
 * and connect our channel to it.  This should only get called
 * if `multilink' was set at the time establish_ppp was called.
 * In demand mode this uses our existing bundle instead of making
 * a new one.
 */
void make_new_bundle(int mrru, int mtru, int rssn, int tssn)
{
        if (!new_style_driver)
                return;

        /* make us a ppp unit */
        if (make_ppp_unit() < 0)
                die(1);

        /* set the mrru, mtu and flags */
        cfg_bundle(mrru, mtru, rssn, tssn);
}

/*
 * bundle_attach - attach our link to a given PPP unit.
 * We assume the unit is controlled by another pppd.
 */
int bundle_attach(int ifnum)
{
        if (!new_style_driver)
                return -1;

        if (ioctl(ppp_dev_fd, PPPIOCATTACH, &ifnum) < 0) {
                if (errno == ENXIO)
                        return 0;       /* doesn't still exist */
                fatal("Couldn't attach to interface unit %d: %m\n", ifnum);
        }
        if (ioctl(ppp_fd, PPPIOCCONNECT, &ifnum) < 0)
                fatal("Couldn't connect to interface unit %d: %m", ifnum);
        set_flags(ppp_dev_fd, get_flags(ppp_dev_fd) | SC_MULTILINK);

        ifunit = ifnum;
        return 1;
}

/********************************************************************
 *
 * clean_check - Fetch the flags for the device and generate
 * appropriate error messages.
 */
void clean_check(void)
{
    int x;
    char *s;

    if (still_ppp()) {
        if (ioctl(ppp_fd, 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 = "all had bit 7 set to 1";
                break;
                
            case SC_RCV_B7_1:
                s = "all had bit 7 set to 0";
                break;
                
            case SC_RCV_EVNP:
                s = "all had odd parity";
                break;
                
            case SC_RCV_ODDP:
                s = "all had even parity";
                break;
            }
            
            if (s != NULL) {
                warn("Receive serial link is not 8-bit clean:");
                warn("Problem: %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 B57600
    { 57600, B57600 },
#endif
#ifdef B115200
    { 115200, B115200 },
#endif
#ifdef EXTA
    { 19200, EXTA },
#endif
#ifdef EXTB
    { 38400, EXTB },
#endif
#ifdef B230400
    { 230400, B230400 },
#endif
#ifdef B460800
    { 460800, B460800 },
#endif
    { 0, 0 }
};

/********************************************************************
 *
 * Translate from bits/second to a speed_t.
 */

static int translate_speed (int bps)
{
    struct speed *speedp;

    if (bps != 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 (int speed)
{
    struct speed *speedp;
    
    if (speed != 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(int tty_fd, int local)
{
    int speed;
    struct termios tios;

    setdtr(tty_fd, 1);
    if (tcgetattr(tty_fd, &tios) < 0) {
        if (!ok_error(errno))
            fatal("tcgetattr: %m(%d)", errno);
        return;
    }
    
    if (!restore_term)
        inittermios = tios;
    
    tios.c_cflag     &= ~(CSIZE | CSTOPB | PARENB | CLOCAL);
    tios.c_cflag     |= CS8 | CREAD | HUPCL;

    tios.c_iflag      = IGNBRK | IGNPAR;
    tios.c_oflag      = 0;
    tios.c_lflag      = 0;
    tios.c_cc[VMIN]   = 1;
    tios.c_cc[VTIME]  = 0;
    
    if (local || !modem)
        tios.c_cflag ^= (CLOCAL | HUPCL);

    switch (crtscts) {
    case 1:
        tios.c_cflag |= CRTSCTS;
        break;

    case -2:
        tios.c_iflag     |= IXON | IXOFF;
        tios.c_cc[VSTOP]  = 0x13;       /* DC3 = XOFF = ^S */
        tios.c_cc[VSTART] = 0x11;       /* DC1 = XON  = ^Q */
        break;

    case -1:
        tios.c_cflag &= ~CRTSCTS;
        break;

    default:
        break;
    }
    
    speed = translate_speed(inspeed);
    if (speed) {
        cfsetospeed (&tios, speed);
        cfsetispeed (&tios, speed);
    }
/*
 * We can't proceed if the serial port speed is B0,
 * since that implies that the serial port is disabled.
 */
    else {
        speed = cfgetospeed(&tios);
        if (speed == B0)
            fatal("Baud rate for %s is 0; need explicit baud rate", devnam);
    }

    if (tcsetattr(tty_fd, TCSAFLUSH, &tios) < 0)
        if (!ok_error(errno))
            fatal("tcsetattr: %m");
    
    baud_rate    = baud_rate_of(speed);
    restore_term = 1;
}

/********************************************************************
 *
 * setdtr - control the DTR line on the serial port.
 * This is called from die(), so it shouldn't call die().
 */

void setdtr (int tty_fd, int on)
{
    int modembits = TIOCM_DTR;

    ioctl(tty_fd, (on ? TIOCMBIS : TIOCMBIC), &modembits);
}

/********************************************************************
 *
 * restore_tty - restore the terminal to the saved settings.
 */

void restore_tty (int tty_fd)
{
    if (restore_term) {
        restore_term = 0;
/*
 * Turn off echoing, because otherwise we can get into
 * a loop with the tty and the modem echoing to each other.
 * We presume we are the sole user of this tty device, so
 * when we close it, it will revert to its defaults anyway.
 */
        if (!default_device)
            inittermios.c_lflag &= ~(ECHO | ECHONL);
        
        if (tcsetattr(tty_fd, TCSAFLUSH, &inittermios) < 0) {
            if (! ok_error (errno))
                warn("tcsetattr: %m");
        }
    }
}

/********************************************************************
 *
 * output - Output PPP packet.
 */

void output (int unit, unsigned char *p, int len)
{
    int fd = ppp_fd;
    int proto;

    if (debug)
        dbglog("sent %P", p, len);

    if (len < PPP_HDRLEN)
        return;
    if (new_style_driver) {
        p += 2;
        len -= 2;
        proto = (p[0] << 8) + p[1];
        if (ifunit >= 0 && !(proto >= 0xc000 || proto == PPP_CCPFRAG))
            fd = ppp_dev_fd;
    }
    if (write(fd, p, len) < 0) {
        if (errno == EWOULDBLOCK || errno == ENOBUFS
            || errno == ENXIO || errno == EIO || errno == EINTR)
            warn("write: warning: %m (%d)", errno);
        else
            error("write: %m (%d)", errno);
    }
}

/********************************************************************
 *
 * wait_input - wait until there is data available,
 * for the length of time specified by *timo (indefinite
 * if timo is NULL).
 */

void wait_input(struct timeval *timo)
{
    fd_set ready, exc;
    int n;

    ready = in_fds;
    exc = in_fds;
    n = select(max_in_fd + 1, &ready, NULL, &exc, timo);
    if (n < 0 && errno != EINTR)
        fatal("select: %m(%d)", errno);
}

/*
 * add_fd - add an fd to the set that wait_input waits for.
 */
void add_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(int fd)
{
    FD_CLR(fd, &in_fds);
}


/********************************************************************
 *
 * read_packet - get a PPP packet from the serial device.
 */

int read_packet (unsigned char *buf)
{
    int len, nr;

    len = PPP_MRU + PPP_HDRLEN;
    if (new_style_driver) {
        *buf++ = PPP_ALLSTATIONS;
        *buf++ = PPP_UI;
        len -= 2;
    }
    nr = -1;
    if (ppp_fd >= 0) {
        nr = read(ppp_fd, buf, len);
        if (nr < 0 && errno != EWOULDBLOCK && errno != EIO)
            error("read: %m");
    }
    if (nr < 0 && new_style_driver && ifunit >= 0) {
        /* N.B. we read ppp_fd first since LCP packets come in there. */
        nr = read(ppp_dev_fd, buf, len);
        if (nr < 0 && errno != EWOULDBLOCK && errno != EIO)
            error("read /dev/ppp: %m");
    }
    return (new_style_driver && nr > 0)? nr+2: nr;
}

/********************************************************************
 *
 * get_loop_output - get outgoing packets from the ppp device,
 * 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(void)
{
    int rv = 0;
    int n;

    if (new_style_driver) {
        while ((n = read_packet(inpacket_buf)) > 0)
            if (loop_frame(inpacket_buf, n))
                rv = 1;
        return rv;
    }

    while ((n = read(master_fd, 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(%d)", errno);

    return rv;
}

/********************************************************************
 *
 * ppp_send_config - configure the transmit characteristics of
 * the ppp interface.
 */

void ppp_send_config (int unit,int mtu,u_int32_t asyncmap,int pcomp,int accomp)
{
    u_int x;
    struct ifreq ifr;
  
    SYSDEBUG ((LOG_DEBUG, "send_config: mtu = %d\n", mtu));
/*
 * Set the MTU and other parameters for the ppp device
 */
    memset (&ifr, '\0', sizeof (ifr));
    strlcpy(ifr.ifr_name, ifname, sizeof (ifr.ifr_name));
    ifr.ifr_mtu = mtu;
        
    if (ifunit >= 0 && ioctl(sock_fd, SIOCSIFMTU, (caddr_t) &ifr) < 0)
        fatal("ioctl(SIOCSIFMTU): %m(%d)", errno);
    link_mtu = mtu;

    if (!still_ppp())
        return;
    SYSDEBUG ((LOG_DEBUG, "send_config: asyncmap = %lx\n", asyncmap));
    if (ioctl(ppp_fd, PPPIOCSASYNCMAP, (caddr_t) &asyncmap) < 0) {
        if (!ok_error(errno))
            fatal("ioctl(PPPIOCSASYNCMAP): %m(%d)", errno);
        return;
    }
    
    x = get_flags(ppp_fd);
    x = pcomp  ? x | SC_COMP_PROT : x & ~SC_COMP_PROT;
    x = accomp ? x | SC_COMP_AC   : x & ~SC_COMP_AC;
    x = sync_serial ? x | SC_SYNC : x & ~SC_SYNC;
    set_flags(ppp_fd, x);
}

/********************************************************************
 *
 * ppp_set_xaccm - set the extended transmit ACCM for the interface.
 */

void ppp_set_xaccm (int unit, ext_accm accm)
{
    SYSDEBUG ((LOG_DEBUG, "set_xaccm: %08lx %08lx %08lx %08lx\n",
                accm[0], accm[1], accm[2], accm[3]));

    if (!still_ppp())
        return;
    if (ioctl(ppp_fd, PPPIOCSXASYNCMAP, accm) < 0 && errno != ENOTTY) {
        if ( ! ok_error (errno))
            warn("ioctl(set extended ACCM): %m(%d)", errno);
    }
}

/********************************************************************
 *
 * ppp_recv_config - configure the receive-side characteristics of
 * the ppp interface.
 */

void ppp_recv_config (int unit,int mru,u_int32_t asyncmap,int pcomp,int accomp)
{
    SYSDEBUG ((LOG_DEBUG, "recv_config: mru = %d\n", mru));
/*
 * If we were called because the link has gone down then there is nothing
 * which may be done. Just return without incident.
 */
    if (!still_ppp())
        return;
/*
 * Set the receiver parameters
 */
    if (ioctl(ppp_fd, PPPIOCSMRU, (caddr_t) &mru) < 0) {
        if ( ! ok_error (errno))
            error("ioctl(PPPIOCSMRU): %m(%d)", errno);
    }
    if (new_style_driver && ifunit >= 0
        && ioctl(ppp_dev_fd, PPPIOCSMRU, (caddr_t) &mru) < 0)
        error("Couldn't set MRU in generic PPP layer: %m");

    SYSDEBUG ((LOG_DEBUG, "recv_config: asyncmap = %lx\n", asyncmap));
    if (ioctl(ppp_fd, PPPIOCSRASYNCMAP, (caddr_t) &asyncmap) < 0) {
        if (!ok_error(errno))
            error("ioctl(PPPIOCSRASYNCMAP): %m(%d)", errno);
    }
}

/********************************************************************
 *
 * ccp_test - ask kernel whether a given compression method
 * is acceptable for use.
 */

int ccp_test (int unit, u_char *opt_ptr, int opt_len, int for_transmit)
{
    struct ppp_option_data data;

    memset (&data, '\0', sizeof (data));
    data.ptr      = opt_ptr;
    data.length   = opt_len;
    data.transmit = for_transmit;

    if (ioctl(ppp_dev_fd, 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 (int unit, int isopen, int isup)
{
    if (still_ppp()) {
        int x = get_flags(ppp_dev_fd);
        x = isopen? x | SC_CCP_OPEN : x &~ SC_CCP_OPEN;
        x = isup?   x | SC_CCP_UP   : x &~ SC_CCP_UP;
        set_flags (ppp_dev_fd, x);
    }
}

/********************************************************************
 *
 * 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(ppp_dev_fd, 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));

    req.stats_ptr = (caddr_t) &req.stats;
    strlcpy(req.ifr__name, ifname, sizeof(req.ifr__name));
    if (ioctl(sock_fd, 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;
}

/********************************************************************
 *
 * 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 (int unit)
{
    int x = get_flags(ppp_dev_fd);

    return x & SC_DC_FERROR;
}

/********************************************************************
 *
 * path_to_procfs - find the path to the proc file system mount point
 */
static char proc_path[MAXPATHLEN];
static int proc_path_len;

static char *path_to_procfs(const char *tail)
{
    struct mntent *mntent;
    FILE *fp;

    if (proc_path_len == 0) {
        /* Default the mount location of /proc */
        strlcpy (proc_path, "/proc", sizeof(proc_path));
        proc_path_len = 5;
        fp = fopen(MOUNTED, "r");
        if (fp != NULL) {
            while ((mntent = getmntent(fp)) != NULL) {
                if (strcmp(mntent->mnt_type, MNTTYPE_IGNORE) == 0)
                    continue;
                if (strcmp(mntent->mnt_type, "proc") == 0) {
                    strlcpy(proc_path, mntent->mnt_dir, sizeof(proc_path));
                    proc_path_len = strlen(proc_path);
                    break;
                }
            }
            fclose (fp);
        }
    }

    strlcpy(proc_path + proc_path_len, tail,
            sizeof(proc_path) - proc_path_len);
    return proc_path;
}

/*
 * /proc/net/route parsing stuff.
 */
#define ROUTE_MAX_COLS  12
FILE *route_fd = (FILE *) 0;
static char route_buffer[512];
static int route_dev_col, route_dest_col, route_gw_col;
static int route_flags_col, route_mask_col;
static int route_num_cols;

static int open_route_table (void);
static void close_route_table (void);
static int read_route_table (struct rtentry *rt);

/********************************************************************
 *
 * close_route_table - close the interface to the route table
 */

static void close_route_table (void)
{
    if (route_fd != (FILE *) 0) {
        fclose (route_fd);
        route_fd = (FILE *) 0;
    }
}

/********************************************************************
 *
 * open_route_table - open the interface to the route table
 */
static char route_delims[] = " \t\n";

static int open_route_table (void)
{
    char *path;

    close_route_table();

    path = path_to_procfs("/net/route");
    route_fd = fopen (path, "r");
    if (route_fd == NULL) {
        error("can't open routing table %s: %m", path);
        return 0;
    }

    route_dev_col = 0;          /* default to usual columns */
    route_dest_col = 1;
    route_gw_col = 2;
    route_flags_col = 3;
    route_mask_col = 7;
    route_num_cols = 8;

    /* parse header line */
    if (fgets(route_buffer, sizeof(route_buffer), route_fd) != 0) {
        char *p = route_buffer, *q;
        int col;
        for (col = 0; col < ROUTE_MAX_COLS; ++col) {
            int used = 1;
            if ((q = strtok(p, route_delims)) == 0)
                break;
            if (strcasecmp(q, "iface") == 0)
                route_dev_col = col;
            else if (strcasecmp(q, "destination") == 0)
                route_dest_col = col;
            else if (strcasecmp(q, "gateway") == 0)
                route_gw_col = col;
            else if (strcasecmp(q, "flags") == 0)
                route_flags_col = col;
            else if (strcasecmp(q, "mask") == 0)
                route_mask_col = col;
            else
                used = 0;
            if (used && col >= route_num_cols)
                route_num_cols = col + 1;
            p = NULL;
        }
    }

    return 1;
}

/********************************************************************
 *
 * read_route_table - read the next entry from the route table
 */

static int read_route_table(struct rtentry *rt)
{
    char *cols[ROUTE_MAX_COLS], *p;
    int col;
        
    memset (rt, '\0', sizeof (struct rtentry));

    if (fgets (route_buffer, sizeof (route_buffer), route_fd) == (char *) 0)
        return 0;

    p = route_buffer;
    for (col = 0; col < route_num_cols; ++col) {
        cols[col] = strtok(p, route_delims);
        if (cols[col] == NULL)
            return 0;           /* didn't get enough columns */
        p = NULL;
    }

    SIN_ADDR(rt->rt_dst) = strtoul(cols[route_dest_col], NULL, 16);
    SIN_ADDR(rt->rt_gateway) = strtoul(cols[route_gw_col], NULL, 16);
    SIN_ADDR(rt->rt_genmask) = strtoul(cols[route_mask_col], NULL, 16);

    rt->rt_flags = (short) strtoul(cols[route_flags_col], NULL, 16);
    rt->rt_dev   = cols[route_dev_col];

    return 1;
}

/********************************************************************
 *
 * defaultroute_exists - determine if there is a default route
 */

static int defaultroute_exists (struct rtentry *rt)
{
    int result = 0;

    if (!open_route_table())
        return 0;

    while (read_route_table(rt) != 0) {
        if ((rt->rt_flags & RTF_UP) == 0)
            continue;

        if (kernel_version > KVERSION(2,1,0) && SIN_ADDR(rt->rt_genmask) != 0)
            continue;
        if (SIN_ADDR(rt->rt_dst) == 0L) {
            result = 1;
            break;
        }
    }

    close_route_table();
    return result;
}

/*
 * have_route_to - determine if the system has any route to
 * a given IP address.  `addr' is in network byte order.
 * Return value is 1 if yes, 0 if no, -1 if don't know.
 * For demand mode to work properly, we have to ignore routes
 * through our own interface.
 */
int have_route_to(u_int32_t addr)
{
    struct rtentry rt;
    int result = 0;

    if (!open_route_table())
        return -1;              /* don't know */

    while (read_route_table(&rt)) {
        if ((rt.rt_flags & RTF_UP) == 0 || strcmp(rt.rt_dev, ifname) == 0)
            continue;
        if ((addr & SIN_ADDR(rt.rt_genmask)) == SIN_ADDR(rt.rt_dst)) {
            result = 1;
            break;
        }
    }

    close_route_table();
    return result;
}

/********************************************************************
 *
 * sifdefaultroute - assign a default route through the address given.
 */

int sifdefaultroute (int unit, u_int32_t ouraddr, u_int32_t gateway)
{
    struct rtentry rt;

    if (defaultroute_exists(&rt) && strcmp(rt.rt_dev, ifname) != 0) {
        u_int32_t old_gateway = SIN_ADDR(rt.rt_gateway);

        if (old_gateway != gateway)
            error("not replacing existing default route to %s [%I]",
                  rt.rt_dev, old_gateway);
        return 0;
    }

    memset (&rt, '\0', sizeof (rt));
    SET_SA_FAMILY (rt.rt_dst,     AF_INET);
    SET_SA_FAMILY (rt.rt_gateway, AF_INET);

    if (kernel_version > KVERSION(2,1,0)) {
        SET_SA_FAMILY (rt.rt_genmask, AF_INET);
        SIN_ADDR(rt.rt_genmask) = 0L;
    }

    SIN_ADDR(rt.rt_gateway) = gateway;
    
    rt.rt_flags = RTF_UP | RTF_GATEWAY;
    if (ioctl(sock_fd, SIOCADDRT, &rt) < 0) {
        if ( ! ok_error ( errno ))
            error("default route ioctl(SIOCADDRT): %m(%d)", errno);
        return 0;
    }

    default_route_gateway = gateway;
    return 1;
}

/********************************************************************
 *
 * cifdefaultroute - delete a default route through the address given.
 */

int cifdefaultroute (int unit, u_int32_t ouraddr, u_int32_t gateway)
{
    struct rtentry rt;

    default_route_gateway = 0;

    memset (&rt, '\0', sizeof (rt));
    SET_SA_FAMILY (rt.rt_dst,     AF_INET);
    SET_SA_FAMILY (rt.rt_gateway, AF_INET);

    if (kernel_version > KVERSION(2,1,0)) {
        SET_SA_FAMILY (rt.rt_genmask, AF_INET);
        SIN_ADDR(rt.rt_genmask) = 0L;
    }

    SIN_ADDR(rt.rt_gateway) = gateway;
    
    rt.rt_flags = RTF_UP | RTF_GATEWAY;
    if (ioctl(sock_fd, SIOCDELRT, &rt) < 0 && errno != ESRCH) {
        if (still_ppp()) {
            if ( ! ok_error ( errno ))
                error("default route ioctl(SIOCDELRT): %m (%d)", errno);
            return 0;
        }
    }

    return 1;
}

/********************************************************************
 *
 * sifproxyarp - Make a proxy ARP entry for the peer.
 */

int sifproxyarp (int unit, u_int32_t his_adr)
{
    struct arpreq arpreq;
    char *forw_path;

    if (has_proxy_arp == 0) {
        memset (&arpreq, '\0', sizeof(arpreq));
    
        SET_SA_FAMILY(arpreq.arp_pa, AF_INET);
        SIN_ADDR(arpreq.arp_pa) = his_adr;
        arpreq.arp_flags = ATF_PERM | ATF_PUBL;
/*
 * Get the hardware address of an interface on the same subnet
 * as our local address.
 */
        if (!get_ether_addr(his_adr, &arpreq.arp_ha, proxy_arp_dev,
                            sizeof(proxy_arp_dev))) {
            error("Cannot determine ethernet address for proxy ARP");
            return 0;
        }
        strlcpy(arpreq.arp_dev, proxy_arp_dev, sizeof(arpreq.arp_dev));

        if (ioctl(sock_fd, SIOCSARP, (caddr_t)&arpreq) < 0) {
            if ( ! ok_error ( errno ))
                error("ioctl(SIOCSARP): %m(%d)", errno);
            return 0;
        }
        proxy_arp_addr = his_adr;
        has_proxy_arp = 1;

        if (tune_kernel) {
            forw_path = path_to_procfs("/sys/net/ipv4/ip_forward");
            if (forw_path != 0) {
                int fd = open(forw_path, O_WRONLY);
                if (fd >= 0) {
                    if (write(fd, "1", 1) != 1)
                        error("Couldn't enable IP forwarding: %m");
                    close(fd);
                }
            }
        }
    }

    return 1;
}

/********************************************************************
 *
 * cifproxyarp - Delete the proxy ARP entry for the peer.
 */

int cifproxyarp (int unit, u_int32_t his_adr)
{
    struct arpreq arpreq;

    if (has_proxy_arp) {
        has_proxy_arp = 0;
        memset (&arpreq, '\0', sizeof(arpreq));
        SET_SA_FAMILY(arpreq.arp_pa, AF_INET);
        SIN_ADDR(arpreq.arp_pa) = his_adr;
        arpreq.arp_flags = ATF_PERM | ATF_PUBL;
        strlcpy(arpreq.arp_dev, proxy_arp_dev, sizeof(arpreq.arp_dev));

        if (ioctl(sock_fd, SIOCDARP, (caddr_t)&arpreq) < 0) {
            if ( ! ok_error ( errno ))
                warn("ioctl(SIOCDARP): %m(%d)", errno);
            return 0;
        }
    }
    return 1;
}
     
/********************************************************************
 *
 * get_ether_addr - get the hardware address of an interface on the
 * the same subnet as ipaddr.
 */

static int get_ether_addr (u_int32_t ipaddr,
                           struct sockaddr *hwaddr,
                           char *name, int namelen)
{
    struct ifreq *ifr, *ifend;
    u_int32_t ina, mask;
    char *aliasp;
    struct ifreq ifreq;
    struct ifconf ifc;
    struct ifreq ifs[MAX_IFS];
    
    ifc.ifc_len = sizeof(ifs);
    ifc.ifc_req = ifs;
    if (ioctl(sock_fd, SIOCGIFCONF, &ifc) < 0) {
        if ( ! ok_error ( errno ))
            error("ioctl(SIOCGIFCONF): %m(%d)", errno);
        return 0;
    }

    SYSDEBUG ((LOG_DEBUG, "proxy arp: scanning %d interfaces for IP %s",
                ifc.ifc_len / sizeof(struct ifreq), ip_ntoa(ipaddr)));
/*
 * Scan through looking for an interface with an Internet
 * address on the same subnet as `ipaddr'.
 */
    ifend = ifs + (ifc.ifc_len / sizeof(struct ifreq));
    for (ifr = ifc.ifc_req; ifr < ifend; ifr++) {
        if (ifr->ifr_addr.sa_family == AF_INET) {
            ina = SIN_ADDR(ifr->ifr_addr);
            strlcpy(ifreq.ifr_name, ifr->ifr_name, sizeof(ifreq.ifr_name));
            SYSDEBUG ((LOG_DEBUG, "proxy arp: examining interface %s",
                        ifreq.ifr_name));
/*
 * Check that the interface is up, and not point-to-point
 * nor loopback.
 */
            if (ioctl(sock_fd, SIOCGIFFLAGS, &ifreq) < 0)
                continue;

            if (((ifreq.ifr_flags ^ FLAGS_GOOD) & FLAGS_MASK) != 0)
                continue;
/*
 * Get its netmask and check that it's on the right subnet.
 */
            if (ioctl(sock_fd, SIOCGIFNETMASK, &ifreq) < 0)
                continue;

            mask = SIN_ADDR(ifreq.ifr_addr);
            SYSDEBUG ((LOG_DEBUG, "proxy arp: interface addr %s mask %lx",
                        ip_ntoa(ina), ntohl(mask)));

            if (((ipaddr ^ ina) & mask) != 0)
                continue;
            break;
        }
    }
    
    if (ifr >= ifend)
        return 0;

    strlcpy(name, ifreq.ifr_name, namelen);

    /* trim off the :1 in eth0:1 */
    aliasp = strchr(name, ':');
    if (aliasp != 0)
        *aliasp = 0;

    info("found interface %s for proxy arp", name);
/*
 * Now get the hardware address.
 */
    memset (&ifreq.ifr_hwaddr, 0, sizeof (struct sockaddr));
    if (ioctl (sock_fd, SIOCGIFHWADDR, &ifreq) < 0) {
        error("SIOCGIFHWADDR(%s): %m(%d)", ifreq.ifr_name, errno);
        return 0;
    }

    memcpy (hwaddr,
            &ifreq.ifr_hwaddr,
            sizeof (struct sockaddr));

    SYSDEBUG ((LOG_DEBUG,
           "proxy arp: found hwaddr %02x:%02x:%02x:%02x:%02x:%02x:%02x:%02x",
                (int) ((unsigned char *) &hwaddr->sa_data)[0],
                (int) ((unsigned char *) &hwaddr->sa_data)[1],
                (int) ((unsigned char *) &hwaddr->sa_data)[2],
                (int) ((unsigned char *) &hwaddr->sa_data)[3],
                (int) ((unsigned char *) &hwaddr->sa_data)[4],
                (int) ((unsigned char *) &hwaddr->sa_data)[5],
                (int) ((unsigned char *) &hwaddr->sa_data)[6],
                (int) ((unsigned char *) &hwaddr->sa_data)[7]));
    return 1;
}

/*
 * get_if_hwaddr - get the hardware address for the specified
 * network interface device.
 */
int
get_if_hwaddr(u_char *addr, char *name)
{
        struct ifreq ifreq;
        int ret, sock_fd;

        sock_fd = socket(AF_INET, SOCK_DGRAM, 0);
        if (sock_fd < 0)
                return 0;
        memset(&ifreq.ifr_hwaddr, 0, sizeof(struct sockaddr));
        strlcpy(ifreq.ifr_name, name, sizeof(ifreq.ifr_name));
        ret = ioctl(sock_fd, SIOCGIFHWADDR, &ifreq);
        close(sock_fd);
        if (ret >= 0)
                memcpy(addr, ifreq.ifr_hwaddr.sa_data, 6);
        return ret;
}

/*
 * get_first_ethernet - return the name of the first ethernet-style
 * interface on this system.
 */
char *
get_first_ethernet()
{
        return "eth0";
}

/********************************************************************
 *
 * 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 (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(sock_fd, SIOCGIFCONF, &ifc) < 0) {
        if ( ! ok_error ( errno ))
            warn("ioctl(SIOCGIFCONF): %m(%d)", errno);
        return mask;
    }
    
    ifend = (struct ifreq *) (ifc.ifc_buf + ifc.ifc_len);
    for (ifr = ifc.ifc_req; ifr < ifend; ifr++) {
/*
 * Check the interface's internet address.
 */
        if (ifr->ifr_addr.sa_family != AF_INET)
            continue;
        ina = SIN_ADDR(ifr->ifr_addr);
        if (((ntohl(ina) ^ addr) & nmask) != 0)
            continue;
/*
 * Check that the interface is up, and not point-to-point nor loopback.
 */
        strlcpy(ifreq.ifr_name, ifr->ifr_name, sizeof(ifreq.ifr_name));
        if (ioctl(sock_fd, SIOCGIFFLAGS, &ifreq) < 0)
            continue;
        
        if (((ifreq.ifr_flags ^ FLAGS_GOOD) & FLAGS_MASK) != 0)
            continue;
/*
 * Get its netmask and OR it into our mask.
 */
        if (ioctl(sock_fd, SIOCGIFNETMASK, &ifreq) < 0)
            continue;
        mask |= SIN_ADDR(ifreq.ifr_addr);
        break;
    }
    return mask;
}

/********************************************************************
 *
 * Internal routine to decode the version.modification.patch level
 */

static void decode_version (char *buf, int *version,
                            int *modification, int *patch)
{
    *version      = (int) strtoul (buf, &buf, 10);
    *modification = 0;
    *patch        = 0;
    
    if (*buf == '.') {
        ++buf;
        *modification = (int) strtoul (buf, &buf, 10);
        if (*buf == '.') {
            ++buf;
            *patch = (int) strtoul (buf, &buf, 10);
        }
    }
    
    if (*buf != '\0') {
        *version      =
        *modification =
        *patch        = 0;
    }
}

/********************************************************************
 *
 * Procedure to determine if the PPP line discipline is registered.
 */

static int
ppp_registered(void)
{
    int local_fd;
    int mfd = -1;
    int ret = 0;
    char slave[16];

    /*
     * We used to open the serial device and set it to the ppp line
     * discipline here, in order to create a ppp unit.  But that is
     * not a good idea - the user might have specified a device that
     * they can't open (permission, or maybe it doesn't really exist).
     * So we grab a pty master/slave pair and use that.
     */
    if (!get_pty(&mfd, &local_fd, slave, 0)) {
        no_ppp_msg = "Couldn't determine if PPP is supported (no free ptys)";
        return 0;
    }

    /*
     * Try to put the device into the PPP discipline.
     */
    if (ioctl(local_fd, TIOCSETD, &ppp_disc) < 0) {
        error("ioctl(TIOCSETD(PPP)): %m(%d)", errno);
    } else
        ret = 1;
    
    close(local_fd);
    close(mfd);
    return ret;
}

/********************************************************************
 *
 * 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(void)
{
    int s, ok, fd;
    struct ifreq ifr;
    int    size;
    int    my_version, my_modification, my_patch;
    int osmaj, osmin, ospatch;

    no_ppp_msg = 
        "This system lacks kernel support for PPP.  This could be because\n"
        "the PPP kernel module could not be loaded, or because PPP was not\n"
        "included in the kernel configuration.  If PPP was included as a\n"
        "module, try `/sbin/modprobe -v ppp'.  If that fails, check that\n"
        "ppp.o exists in /lib/modules/`uname -r`/net.\n"
        "See README.linux file in the ppp distribution for more details.\n";

    /* get the kernel version now, since we are called before sys_init */
    uname(&utsname);
    osmaj = osmin = ospatch = 0;
    sscanf(utsname.release, "%d.%d.%d", &osmaj, &osmin, &ospatch);
    kernel_version = KVERSION(osmaj, osmin, ospatch);

    fd = open("/dev/ppp", O_RDWR);
#if 0
    if (fd < 0 && errno == ENOENT) {
        /* try making it and see if that helps. */
        if (mknod("/dev/ppp", S_IFCHR | S_IRUSR | S_IWUSR,
                  makedev(108, 0)) >= 0) {
            fd = open("/dev/ppp", O_RDWR);
            if (fd >= 0)
                info("Created /dev/ppp device node");
            else
                unlink("/dev/ppp");     /* didn't work, undo the mknod */
        } else if (errno == EEXIST) {
            fd = open("/dev/ppp", O_RDWR);
        }
    }
#endif /* 0 */
    if (fd >= 0) {
        new_style_driver = 1;

        /* XXX should get from driver */
        driver_version = 2;
        driver_modification = 4;
        driver_patch = 0;
        close(fd);
        return 1;
    }
    if (kernel_version >= KVERSION(2,3,13))
        return 0;

/*
 * Open a socket for doing the ioctl operations.
 */    
    s = socket(AF_INET, SOCK_DGRAM, 0);
    if (s < 0)
        return 0;
    
    strlcpy (ifr.ifr_name, "ppp0", sizeof (ifr.ifr_name));
    ok = ioctl(s, SIOCGIFFLAGS, (caddr_t) &ifr) >= 0;
/*
 * If the device did not exist then attempt to create one by putting the
 * current tty into the PPP discipline. If this works then obtain the
 * flags for the device again.
 */
    if (!ok) {
        if (ppp_registered()) {
            strlcpy (ifr.ifr_name, "ppp0", sizeof (ifr.ifr_name));
            ok = ioctl(s, SIOCGIFFLAGS, (caddr_t) &ifr) >= 0;
        }
    }
/*
 * Ensure that the hardware address is for PPP and not something else
 */
    if (ok)
        ok = ioctl (s, SIOCGIFHWADDR, (caddr_t) &ifr) >= 0;

    if (ok && ((ifr.ifr_hwaddr.sa_family & ~0xFF) != ARPHRD_PPP))
        ok = 0;

/*
 *  This is the PPP device. Validate the version of the driver at this
 *  point to ensure that this program will work with the driver.
 */
    if (ok) {
        char   abBuffer [1024];

        ifr.ifr_data = abBuffer;
        size = ioctl (s, SIOCGPPPVER, (caddr_t) &ifr);
        if (size < 0) {
            error("Couldn't read driver version: %m");
            ok = 0;
            no_ppp_msg = "Sorry, couldn't verify kernel driver version\n";

        } else {
            decode_version(abBuffer,
                           &driver_version,
                           &driver_modification,
                           &driver_patch);
/*
 * Validate the version of the driver against the version that we used.
 */
            decode_version(VERSION,
                           &my_version,
                           &my_modification,
                           &my_patch);

            /* The version numbers must match */
            if (driver_version != my_version)
                ok = 0;
      
            /* The modification levels must be legal */
            if (driver_modification < 3) {
                if (driver_modification >= 2) {
                    /* we can cope with 2.2.0 and above */
                    driver_is_old = 1;
                } else {
                    ok = 0;
                }
            }

            close (s);
            if (!ok) {
                slprintf(route_buffer, sizeof(route_buffer),
                         "Sorry - PPP driver version %d.%d.%d is out of date\n",
                         driver_version, driver_modification, driver_patch);

                no_ppp_msg = route_buffer;
            }
        }
    }
    return ok;
}

/********************************************************************
 *
 * Update the wtmp file with the appropriate user name and tty device.
 */

void logwtmp (const char *line, const char *name, const char *host)
{
    struct utmp ut, *utp;
    pid_t  mypid = getpid();
#if __GLIBC__ < 2
    int    wtmp;
#endif

/*
 * Update the signon database for users.
 * Christoph Lameter: Copied from poeigl-1.36 Jan 3, 1996
 */
    utmpname(_PATH_UTMP);
    setutent();
    while ((utp = getutent()) && (utp->ut_pid != mypid))
        /* nothing */;

    /* Is this call really necessary? There is another one after the 'put' */
    endutent();
    
    if (utp)
        memcpy(&ut, utp, sizeof(ut));
    else
        /* some gettys/telnetds don't initialize utmp... */
        memset(&ut, 0, sizeof(ut));

    if (ut.ut_id[0] == 0)
        strncpy(ut.ut_id, line + 3, sizeof(ut.ut_id));
        
    strncpy(ut.ut_user, name, sizeof(ut.ut_user));
    strncpy(ut.ut_line, line, sizeof(ut.ut_line));

    time(&ut.ut_time);

    ut.ut_type = USER_PROCESS;
    ut.ut_pid  = mypid;

    /* Insert the host name if one is supplied */
    if (*host)
        strncpy (ut.ut_host, host, sizeof(ut.ut_host));

    /* Insert the IP address of the remote system if IP is enabled */
    if (ipcp_protent.enabled_flag && ipcp_hisoptions[0].neg_addr)
        memcpy(&ut.ut_addr, (char *) &ipcp_hisoptions[0].hisaddr,
                 sizeof(ut.ut_addr));
        
    /* CL: Makes sure that the logout works */
    if (*host == 0 && *name==0)
        ut.ut_host[0]=0;

    pututline(&ut);
    endutent();
/*
 * Update the wtmp file.
 */
#if __GLIBC__ >= 2
    updwtmp(_PATH_WTMP, &ut);
#else
    wtmp = open(_PATH_WTMP, O_APPEND|O_WRONLY);
    if (wtmp >= 0) {
        flock(wtmp, LOCK_EX);

        if (write (wtmp, (char *)&ut, sizeof(ut)) != sizeof(ut))
            warn("error writing %s: %m", _PATH_WTMP);

        flock(wtmp, LOCK_UN);

        close (wtmp);
    }
#endif
}


/********************************************************************
 *
 * sifvjcomp - config tcp header compression
 */

int sifvjcomp (int u, int vjcomp, int cidcomp, int maxcid)
{
    u_int x = get_flags(ppp_dev_fd);

    if (vjcomp) {
        if (ioctl (ppp_dev_fd, PPPIOCSMAXCID, (caddr_t) &maxcid) < 0) {
            if (! ok_error (errno))
                error("ioctl(PPPIOCSMAXCID): %m(%d)", errno);
            vjcomp = 0;
        }
    }

    x = vjcomp  ? x | SC_COMP_TCP     : x &~ SC_COMP_TCP;
    x = cidcomp ? x & ~SC_NO_TCP_CCID : x | SC_NO_TCP_CCID;
    set_flags (ppp_dev_fd, x);

    return 1;
}

/********************************************************************
 *
 * sifup - Config the interface up and enable IP packets to pass.
 */

int sifup(int u)
{
    struct ifreq ifr;

    memset (&ifr, '\0', sizeof (ifr));
    strlcpy(ifr.ifr_name, ifname, sizeof (ifr.ifr_name));
    if (ioctl(sock_fd, SIOCGIFFLAGS, (caddr_t) &ifr) < 0) {
        if (! ok_error (errno))
            error("ioctl (SIOCGIFFLAGS): %m(%d)", errno);
        return 0;
    }

    ifr.ifr_flags |= (IFF_UP | IFF_POINTOPOINT);
    if (ioctl(sock_fd, SIOCSIFFLAGS, (caddr_t) &ifr) < 0) {
        if (! ok_error (errno))
            error("ioctl(SIOCSIFFLAGS): %m(%d)", errno);
        return 0;
    }
    if_is_up++;

    return 1;
}

/********************************************************************
 *
 * sifdown - Disable the indicated protocol and config the interface
 *           down if there are no remaining protocols.
 */

int sifdown (int u)
{
    struct ifreq ifr;

    if (if_is_up && --if_is_up > 0)
        return 1;

    memset (&ifr, '\0', sizeof (ifr));
    strlcpy(ifr.ifr_name, ifname, sizeof (ifr.ifr_name));
    if (ioctl(sock_fd, SIOCGIFFLAGS, (caddr_t) &ifr) < 0) {
        if (! ok_error (errno))
            error("ioctl (SIOCGIFFLAGS): %m(%d)", errno);
        return 0;
    }

    ifr.ifr_flags &= ~IFF_UP;
    ifr.ifr_flags |= IFF_POINTOPOINT;
    if (ioctl(sock_fd, SIOCSIFFLAGS, (caddr_t) &ifr) < 0) {
        if (! ok_error (errno))
            error("ioctl(SIOCSIFFLAGS): %m(%d)", errno);
        return 0;
    }
    return 1;
}

/********************************************************************
 *
 * sifaddr - Config the interface IP addresses and netmask.
 */

int sifaddr (int unit, u_int32_t our_adr, u_int32_t his_adr,
             u_int32_t net_mask)
{
    struct ifreq   ifr; 
    struct rtentry rt;
    
    memset (&ifr, '\0', sizeof (ifr));
    memset (&rt,  '\0', sizeof (rt));
    
    SET_SA_FAMILY (ifr.ifr_addr,    AF_INET); 
    SET_SA_FAMILY (ifr.ifr_dstaddr, AF_INET); 
    SET_SA_FAMILY (ifr.ifr_netmask, AF_INET); 

    strlcpy (ifr.ifr_name, ifname, sizeof (ifr.ifr_name));
/*
 *  Set our IP address
 */
    SIN_ADDR(ifr.ifr_addr) = our_adr;
    if (ioctl(sock_fd, SIOCSIFADDR, (caddr_t) &ifr) < 0) {
        if (errno != EEXIST) {
            if (! ok_error (errno))
                error("ioctl(SIOCSIFADDR): %m(%d)", errno);
        }
        else {
            warn("ioctl(SIOCSIFADDR): Address already exists");
        }
        return (0);
    }
/*
 *  Set the gateway address
 */
    SIN_ADDR(ifr.ifr_dstaddr) = his_adr;
    if (ioctl(sock_fd, SIOCSIFDSTADDR, (caddr_t) &ifr) < 0) {
        if (! ok_error (errno))
            error("ioctl(SIOCSIFDSTADDR): %m(%d)", errno); 
        return (0);
    } 
/*
 *  Set the netmask.
 *  For recent kernels, force the netmask to 255.255.255.255.
 */
    if (kernel_version >= KVERSION(2,1,16))
        net_mask = ~0L;
    if (net_mask != 0) {
        SIN_ADDR(ifr.ifr_netmask) = net_mask;
        if (ioctl(sock_fd, SIOCSIFNETMASK, (caddr_t) &ifr) < 0) {
            if (! ok_error (errno))
                error("ioctl(SIOCSIFNETMASK): %m(%d)", errno); 
            return (0);
        } 
    }
/*
 *  Add the device route
 */
    if (kernel_version < KVERSION(2,1,16)) {
        SET_SA_FAMILY (rt.rt_dst,     AF_INET);
        SET_SA_FAMILY (rt.rt_gateway, AF_INET);
        rt.rt_dev = ifname;

        SIN_ADDR(rt.rt_gateway) = 0L;
        SIN_ADDR(rt.rt_dst)     = his_adr;
        rt.rt_flags = RTF_UP | RTF_HOST;

        if (kernel_version > KVERSION(2,1,0)) {
            SET_SA_FAMILY (rt.rt_genmask, AF_INET);
            SIN_ADDR(rt.rt_genmask) = -1L;
        }

        if (ioctl(sock_fd, SIOCADDRT, &rt) < 0) {
            if (! ok_error (errno))
                error("ioctl(SIOCADDRT) device route: %m(%d)", errno);
            return (0);
        }
    }

    /* set ip_dynaddr in demand mode if address changes */
    if (demand && tune_kernel && !dynaddr_set
        && our_old_addr && our_old_addr != our_adr) {
        /* set ip_dynaddr if possible */
        char *path;
        int fd;

        path = path_to_procfs("/sys/net/ipv4/ip_dynaddr");
        if (path != 0 && (fd = open(path, O_WRONLY)) >= 0) {
            if (write(fd, "1", 1) != 1)
                error("Couldn't enable dynamic IP addressing: %m");
            close(fd);
        }
        dynaddr_set = 1;        /* only 1 attempt */
    }
    our_old_addr = 0;

    return 1;
}

/********************************************************************
 *
 * cifaddr - Clear the interface IP addresses, and delete routes
 * through the interface if possible.
 */

int cifaddr (int unit, u_int32_t our_adr, u_int32_t his_adr)
{
    struct ifreq ifr;

    if (kernel_version < KVERSION(2,1,16)) {
/*
 *  Delete the route through the device
 */
        struct rtentry rt;
        memset (&rt, '\0', sizeof (rt));

        SET_SA_FAMILY (rt.rt_dst,     AF_INET);
        SET_SA_FAMILY (rt.rt_gateway, AF_INET);
        rt.rt_dev = ifname;

        SIN_ADDR(rt.rt_gateway) = 0;
        SIN_ADDR(rt.rt_dst)     = his_adr;
        rt.rt_flags = RTF_UP | RTF_HOST;

        if (kernel_version > KVERSION(2,1,0)) {
            SET_SA_FAMILY (rt.rt_genmask, AF_INET);
            SIN_ADDR(rt.rt_genmask) = -1L;
        }

        if (ioctl(sock_fd, SIOCDELRT, &rt) < 0 && errno != ESRCH) {
            if (still_ppp() && ! ok_error (errno))
                error("ioctl(SIOCDELRT) device route: %m(%d)", errno);
            return (0);
        }
    }

    /* This way it is possible to have an IPX-only or IPv6-only interface */
    memset(&ifr, 0, sizeof(ifr));
    SET_SA_FAMILY(ifr.ifr_addr, AF_INET);
    strlcpy(ifr.ifr_name, ifname, sizeof(ifr.ifr_name));
    
    if (ioctl(sock_fd, SIOCSIFADDR, (caddr_t) &ifr) < 0) {
        if (! ok_error (errno)) {
            error("ioctl(SIOCSIFADDR): %m(%d)", errno);
            return 0;
        }
    }

    our_old_addr = our_adr;

    return 1;
}

#ifdef INET6
/********************************************************************
 * 
 * sif6addr - Config the interface with an IPv6 link-local address
 */
int sif6addr (int unit, eui64_t our_eui64, eui64_t his_eui64)
{
    struct in6_ifreq ifr6;
    struct ifreq ifr;
    struct in6_rtmsg rt6;

    memset(&ifr, 0, sizeof (ifr));
    strlcpy(ifr.ifr_name, ifname, sizeof(ifr.ifr_name));
    if (ioctl(sock6_fd, SIOCGIFINDEX, (caddr_t) &ifr) < 0) {
        error("sif6addr: ioctl(SIOCGIFINDEX): %m (%d)", errno);
        return 0;
    }
    
    /* Local interface */
    memset(&ifr6, 0, sizeof(ifr6));
    IN6_LLADDR_FROM_EUI64(ifr6.ifr6_addr, our_eui64);
    ifr6.ifr6_ifindex = ifr.ifr_ifindex;
    ifr6.ifr6_prefixlen = 10;

    if (ioctl(sock6_fd, SIOCSIFADDR, &ifr6) < 0) {
        error("sif6addr: ioctl(SIOCSIFADDR): %m (%d)", errno);
        return 0;
    }
    
    /* Route to remote host */
    memset(&rt6, 0, sizeof(rt6));
    IN6_LLADDR_FROM_EUI64(rt6.rtmsg_dst, his_eui64);
    rt6.rtmsg_flags = RTF_UP;
    rt6.rtmsg_dst_len = 10;
    rt6.rtmsg_ifindex = ifr.ifr_ifindex;
    rt6.rtmsg_metric = 1;
    
    if (ioctl(sock6_fd, SIOCADDRT, &rt6) < 0) {
        error("sif6addr: ioctl(SIOCADDRT): %m (%d)", errno);
        return 0;
    }

    return 1;
}


/********************************************************************
 *
 * cif6addr - Remove IPv6 address from interface
 */
int cif6addr (int unit, eui64_t our_eui64, eui64_t his_eui64)
{
    struct ifreq ifr;
    struct in6_ifreq ifr6;

    memset(&ifr, 0, sizeof(ifr));
    strlcpy(ifr.ifr_name, ifname, sizeof(ifr.ifr_name));
    if (ioctl(sock6_fd, SIOCGIFINDEX, (caddr_t) &ifr) < 0) {
        error("cif6addr: ioctl(SIOCGIFINDEX): %m (%d)", errno);
        return 0;
    }
    
    memset(&ifr6, 0, sizeof(ifr6));
    IN6_LLADDR_FROM_EUI64(ifr6.ifr6_addr, our_eui64);
    ifr6.ifr6_ifindex = ifr.ifr_ifindex;
    ifr6.ifr6_prefixlen = 10;

    if (ioctl(sock6_fd, SIOCDIFADDR, &ifr6) < 0) {
        if (errno != EADDRNOTAVAIL) {
            if (! ok_error (errno))
                error("cif6addr: ioctl(SIOCDIFADDR): %m (%d)", errno);
        }
        else {
            warn("cif6addr: ioctl(SIOCDIFADDR): No such address");
        }
        return (0);
    }
    return 1;
}
#endif /* INET6 */

/*
 * get_pty - get a pty master/slave pair and chown the slave side
 * to the uid given.  Assumes slave_name points to >= 16 bytes of space.
 */
int
get_pty(master_fdp, slave_fdp, slave_name, uid)
    int *master_fdp;
    int *slave_fdp;
    char *slave_name;
    int uid;
{
    int i, mfd, sfd = -1;
    char pty_name[16];
    struct termios tios;

#ifdef TIOCGPTN
    /*
     * Try the unix98 way first.
     */
    mfd = open("/dev/ptmx", O_RDWR);
    if (mfd >= 0) {
        int ptn;
        if (ioctl(mfd, TIOCGPTN, &ptn) >= 0) {
            slprintf(pty_name, sizeof(pty_name), "/dev/pts/%d", ptn);
            chmod(pty_name, S_IRUSR | S_IWUSR);
#ifdef TIOCSPTLCK
            ptn = 0;
            if (ioctl(mfd, TIOCSPTLCK, &ptn) < 0)
                warn("Couldn't unlock pty slave %s: %m", pty_name);
#endif
            if ((sfd = open(pty_name, O_RDWR | O_NOCTTY)) < 0)
                warn("Couldn't open pty slave %s: %m", pty_name);
        }
    }
#endif /* TIOCGPTN */

    if (sfd < 0) {
        /* the old way - scan through the pty name space */
        for (i = 0; i < 64; ++i) {
            slprintf(pty_name, sizeof(pty_name), "/dev/pty%c%x",
                     'p' + i / 16, i % 16);
            mfd = open(pty_name, O_RDWR, 0);
            if (mfd >= 0) {
                pty_name[5] = 't';
                sfd = open(pty_name, O_RDWR | O_NOCTTY, 0);
                if (sfd >= 0) {
                    fchown(sfd, uid, -1);
                    fchmod(sfd, S_IRUSR | S_IWUSR);
                    break;
                }
                close(mfd);
            }
        }
    }

    if (sfd < 0)
        return 0;

    strlcpy(slave_name, pty_name, 16);
    *master_fdp = mfd;
    *slave_fdp = sfd;
    if (tcgetattr(sfd, &tios) == 0) {
        tios.c_cflag &= ~(CSIZE | CSTOPB | PARENB);
        tios.c_cflag |= CS8 | CREAD;
        tios.c_iflag  = IGNPAR | CLOCAL;
        tios.c_oflag  = 0;
        tios.c_lflag  = 0;
        if (tcsetattr(sfd, TCSAFLUSH, &tios) < 0)
            warn("couldn't set attributes on pty: %m");
    } else
        warn("couldn't get attributes on pty: %m");

    return 1;
}

/********************************************************************
 *
 * open_loopback - open the device we use for getting packets
 * in demand mode.  Under Linux, we use a pty master/slave pair.
 */
int
open_ppp_loopback(void)
{
    int flags;

    looped = 1;
    if (new_style_driver) {
        /* allocate ourselves a ppp unit */
        if (make_ppp_unit() < 0)
            die(1);
        set_flags(ppp_dev_fd, SC_LOOP_TRAFFIC);
        set_kdebugflag(kdebugflag);
        ppp_fd = -1;
        return ppp_dev_fd;
    }

    if (!get_pty(&master_fd, &slave_fd, loop_name, 0))
        fatal("No free pty for loopback");
    SYSDEBUG(("using %s for loopback", loop_name));

    set_ppp_fd(slave_fd);

    flags = fcntl(master_fd, F_GETFL);
    if (flags == -1 ||
        fcntl(master_fd, F_SETFL, flags | O_NONBLOCK) == -1)
        warn("couldn't set master loopback to nonblock: %m(%d)", errno);

    flags = fcntl(ppp_fd, F_GETFL);
    if (flags == -1 ||
        fcntl(ppp_fd, F_SETFL, flags | O_NONBLOCK) == -1)
        warn("couldn't set slave loopback to nonblock: %m(%d)", errno);

    if (ioctl(ppp_fd, TIOCSETD, &ppp_disc) < 0)
        fatal("ioctl(TIOCSETD): %m(%d)", errno);
/*
 * Find out which interface we were given.
 */
    if (ioctl(ppp_fd, PPPIOCGUNIT, &ifunit) < 0)
        fatal("ioctl(PPPIOCGUNIT): %m(%d)", errno);
/*
 * Enable debug in the driver if requested.
 */
    set_kdebugflag (kdebugflag);

    return master_fd;
}

/********************************************************************
 *
 * restore_loop - reattach the ppp unit to the loopback.
 *
 * The kernel ppp driver automatically reattaches the ppp unit to
 * the loopback if the serial port is set to a line discipline other
 * than ppp, or if it detects a modem hangup.  The former will happen
 * in disestablish_ppp if the latter hasn't already happened, so we
 * shouldn't need to do anything.
 *
 * Just to be sure, set the real serial port to the normal discipline.
 */

void
restore_loop(void)
{
    looped = 1;
    if (new_style_driver) {
        set_flags(ppp_dev_fd, get_flags(ppp_dev_fd) | SC_LOOP_TRAFFIC);
        return;
    }
    if (ppp_fd != slave_fd) {
        (void) ioctl(ppp_fd, TIOCSETD, &tty_disc);
        set_ppp_fd(slave_fd);
    }
}

/********************************************************************
 *
 * 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(ppp_dev_fd, PPPIOCSNPMODE, (caddr_t) &npi) < 0) {
        if (! ok_error (errno))
            error("ioctl(PPPIOCSNPMODE, %d, %d): %m (%d)",
                   proto, mode, errno);
        return 0;
    }
    return 1;
}

\f
/********************************************************************
 *
 * sipxfaddr - Config the interface IPX networknumber
 */

int sipxfaddr (int unit, unsigned long int network, unsigned char * node )
{
    int    result = 1;

#ifdef IPX_CHANGE
    int    skfd; 
    struct ifreq         ifr;
    struct sockaddr_ipx *sipx = (struct sockaddr_ipx *) &ifr.ifr_addr;

    skfd = socket (AF_IPX, SOCK_DGRAM, 0);
    if (skfd < 0) { 
        if (! ok_error (errno))
            dbglog("socket(AF_IPX): %m (%d)", errno);
        result = 0;
    }
    else {
        memset (&ifr, '\0', sizeof (ifr));
        strlcpy (ifr.ifr_name, ifname, sizeof(ifr.ifr_name));

        memcpy (sipx->sipx_node, node, IPX_NODE_LEN);
        sipx->sipx_family  = AF_IPX;
        sipx->sipx_port    = 0;
        sipx->sipx_network = htonl (network);
        sipx->sipx_type    = IPX_FRAME_ETHERII;
        sipx->sipx_action  = IPX_CRTITF;
/*
 *  Set the IPX device
 */
        if (ioctl(skfd, SIOCSIFADDR, (caddr_t) &ifr) < 0) {
            result = 0;
            if (errno != EEXIST) {
                if (! ok_error (errno))
                    dbglog("ioctl(SIOCSIFADDR, CRTITF): %m (%d)", errno);
            }
            else {
                warn("ioctl(SIOCSIFADDR, CRTITF): Address already exists");
            }
        }
        close (skfd);
    }
#endif
    return result;
}

/********************************************************************
 *
 * cipxfaddr - Clear the information for the IPX network. The IPX routes
 *             are removed and the device is no longer able to pass IPX
 *             frames.
 */

int cipxfaddr (int unit)
{
    int    result = 1;

#ifdef IPX_CHANGE
    int    skfd; 
    struct ifreq         ifr;
    struct sockaddr_ipx *sipx = (struct sockaddr_ipx *) &ifr.ifr_addr;

    skfd = socket (AF_IPX, SOCK_DGRAM, 0);
    if (skfd < 0) { 
        if (! ok_error (errno))
            dbglog("socket(AF_IPX): %m (%d)", errno);
        result = 0;
    }
    else {
        memset (&ifr, '\0', sizeof (ifr));
        strlcpy (ifr.ifr_name, ifname, sizeof(ifr.ifr_name));

        sipx->sipx_type    = IPX_FRAME_ETHERII;
        sipx->sipx_action  = IPX_DLTITF;
        sipx->sipx_family  = AF_IPX;
/*
 *  Set the IPX device
 */
        if (ioctl(skfd, SIOCSIFADDR, (caddr_t) &ifr) < 0) {
            if (! ok_error (errno))
                info("ioctl(SIOCSIFADDR, IPX_DLTITF): %m (%d)", errno);
            result = 0;
        }
        close (skfd);
    }
#endif
    return result;
}

/*
 * Use the hostname as part of the random number seed.
 */
int
get_host_seed()
{
    int h;
    char *p = hostname;

    h = 407;
    for (p = hostname; *p != 0; ++p)
        h = h * 37 + *p;
    return h;
}

/********************************************************************
 *
 * sys_check_options - check the options that the user specified
 */

int
sys_check_options(void)
{
#ifdef IPX_CHANGE
/*
 * Disable the IPX protocol if the support is not present in the kernel.
 */
    char *path;

    if (ipxcp_protent.enabled_flag) {
        struct stat stat_buf;
        if ((path = path_to_procfs("/net/ipx_interface")) == 0
            || lstat(path, &stat_buf) < 0) {
            error("IPX support is not present in the kernel\n");
            ipxcp_protent.enabled_flag = 0;
        }
    }
#endif
    if (demand && driver_is_old) {
        option_error("demand dialling is not supported by kernel driver "
                     "version %d.%d.%d", driver_version, driver_modification,
                     driver_patch);
        return 0;
    }
    if (multilink && !new_style_driver) {
        warn("Warning: multilink is not supported by the kernel driver");
        multilink = 0;
    }
    return 1;
}