Fix bug in CHAP MS v2 handling where we didn't zero enough.

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

/*
 * sys-bsd.c - System-dependent procedures for setting up
 * PPP interfaces on bsd-4.4-ish systems (including 386BSD, NetBSD, etc.)
 *
 * Copyright (c) 1993-2002 Paul Mackerras. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. The name(s) of the authors of this software must not be used to
 *    endorse or promote products derived from this software without
 *    prior written permission.
 *
 * 3. Redistributions of any form whatsoever must retain the following
 *    acknowledgment:
 *    "This product includes software developed by Paul Mackerras
 *     <paulus@samba.org>".
 *
 * THE AUTHORS OF THIS SOFTWARE DISCLAIM ALL WARRANTIES WITH REGARD TO
 * THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
 * AND FITNESS, IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY
 * SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN
 * AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING
 * OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 *
 * Derived from main.c and pppd.h, which are:
 *
 * Copyright (c) 1984-2000 Carnegie Mellon University. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * 3. The name "Carnegie Mellon University" must not be used to
 *    endorse or promote products derived from this software without
 *    prior written permission. For permission or any legal
 *    details, please contact
 *      Office of Technology Transfer
 *      Carnegie Mellon University
 *      5000 Forbes Avenue
 *      Pittsburgh, PA  15213-3890
 *      (412) 268-4387, fax: (412) 268-7395
 *      tech-transfer@andrew.cmu.edu
 *
 * 4. Redistributions of any form whatsoever must retain the following
 *    acknowledgment:
 *    "This product includes software developed by Computing Services
 *     at Carnegie Mellon University (http://www.cmu.edu/computing/)."
 *
 * CARNEGIE MELLON UNIVERSITY DISCLAIMS ALL WARRANTIES WITH REGARD TO
 * THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
 * AND FITNESS, IN NO EVENT SHALL CARNEGIE MELLON UNIVERSITY BE LIABLE
 * FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN
 * AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING
 * OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

#define RCSID   "$Id: sys-bsd.c,v 1.50 2004/11/04 10:02:26 paulus Exp $"
/*      $NetBSD: sys-bsd.c,v 1.1.1.3 1997/09/26 18:53:04 christos Exp $ */

/*
 * TODO:
 */

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <fcntl.h>
#include <termios.h>
#include <signal.h>
#include <sys/ioctl.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/time.h>
#include <sys/stat.h>
#include <sys/param.h>
#ifdef NetBSD1_2
#include <util.h>
#endif
#ifdef PPP_FILTER
#include <net/bpf.h>
#endif

#include <net/if.h>
#include <net/ppp_defs.h>
#include <net/if_ppp.h>
#include <net/route.h>
#include <net/if_dl.h>
#include <netinet/in.h>

#if RTM_VERSION >= 3
#include <sys/param.h>
#if defined(NetBSD) && (NetBSD >= 199703)
#include <netinet/if_inarp.h>
#else   /* NetBSD 1.2D or later */
#ifdef __FreeBSD__
#include <netinet/if_ether.h>
#else
#include <net/if_ether.h>
#endif
#endif
#endif

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

static const char rcsid[] = RCSID;

static int initdisc = -1;       /* Initial TTY discipline for ppp_fd */
static int initfdflags = -1;    /* Initial file descriptor flags for ppp_fd */
static int ppp_fd = -1;         /* fd which is set to PPP discipline */
static int rtm_seq;

static int restore_term;        /* 1 => we've munged the terminal */
static struct termios inittermios; /* Initial TTY termios */
static struct winsize wsinfo;   /* Initial window size info */

static int loop_slave = -1;
static int loop_master;
static char loop_name[20];

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

static int sockfd;              /* socket for doing interface ioctls */

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 if_is_up;            /* the interface is currently up */
static u_int32_t ifaddrs[2];    /* local and remote addresses we set */
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 dodefaultroute __P((u_int32_t, int));
static int get_ether_addr __P((u_int32_t, struct sockaddr_dl *));


/*
 * sys_init - System-dependent initialization.
 */
void
sys_init()
{
    /* 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");

    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 (ifaddrs[0] != 0)
        cifaddr(0, ifaddrs[0], ifaddrs[1]);
    if (default_route_gateway)
        cifdefaultroute(0, 0, default_route_gateway);
    if (proxy_arp_addr)
        cifproxyarp(0, proxy_arp_addr);
}

/*
 * 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);
    }
}

/*
 * sys_check_options - check the options that the user specified
 */
int
sys_check_options()
{
#ifndef CDTRCTS
    if (crtscts == 2) {
        warn("DTR/CTS flow control is not supported on this system");
        return 0;
    }
#endif
    return 1;
}

/*
 * 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 */

    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.bsd\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 (demand) {
        /*
         * Demand mode - prime the old ppp device to relinquish the unit.
         */
        if (ioctl(ppp_fd, PPPIOCXFERUNIT, 0) < 0)
            fatal("ioctl(transfer ppp unit): %m");
    }

    /*
     * Save the old line discipline of fd, and set it to PPP.
     */
    if (ioctl(fd, TIOCGETD, &initdisc) < 0)
        fatal("ioctl(TIOCGETD): %m");
    if (ioctl(fd, TIOCSETD, &pppdisc) < 0)
        fatal("ioctl(TIOCSETD): %m");

    if (!demand) {
        /*
         * Find out which interface we were given.
         */
        if (ioctl(fd, PPPIOCGUNIT, &ifunit) < 0)
            fatal("ioctl(PPPIOCGUNIT): %m");
    } else {
        /*
         * Check that we got the same unit again.
         */
        if (ioctl(fd, PPPIOCGUNIT, &x) < 0)
            fatal("ioctl(PPPIOCGUNIT): %m");
        if (x != ifunit)
            fatal("transfer_ppp failed: wanted unit %d, got %d", ifunit, x);
        x = TTYDISC;
        ioctl(loop_slave, TIOCSETD, &x);
    }

    ppp_fd = fd;

    /*
     * 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.
     */
    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;
}

/*
 * restore_loop - reattach the ppp unit to the loopback.
 */
void
restore_loop()
{
    int x;

    /*
     * Transfer the ppp interface back to the loopback.
     */
    if (ioctl(ppp_fd, 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);
    ppp_fd = loop_slave;
}


/*
 * 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;

    if (fd == ppp_fd)
        ppp_fd = -1;
}

/*
 * Check whether the link seems not to be 8-bit clean.
 */
void
clean_check()
{
    int x;
    char *s;

    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 = "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);
        }
    }
}

/*
 * 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.
 *
 * For *BSD, we assume that speed_t values numerically equal bits/second.
 */
void
set_up_tty(fd, local)
    int fd, local;
{
    struct termios tios;

    if (tcgetattr(fd, &tios) < 0)
        fatal("tcgetattr: %m");

    if (!restore_term) {
        inittermios = tios;
        ioctl(fd, TIOCGWINSZ, &wsinfo);
    }

    tios.c_cflag &= ~(CSIZE | CSTOPB | PARENB | CLOCAL);
    if (crtscts > 0 && !local) {
        if (crtscts == 2) {
#ifdef CDTRCTS
            tios.c_cflag |= CDTRCTS;
#endif
        } else
            tios.c_cflag |= CRTSCTS;
    } else if (crtscts < 0) {
        tios.c_cflag &= ~CRTSCTS;
#ifdef CDTRCTS
        tios.c_cflag &= ~CDTRCTS;
#endif
    }

    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 */
    }

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

    if (tcsetattr(fd, TCSAFLUSH, &tios) < 0)
        fatal("tcsetattr: %m");

    restore_term = 1;
}

/*
 * restore_tty - restore the terminal to the saved settings.
 */
void
restore_tty(fd)
    int fd;
{
    if (restore_term) {
        if (!default_device) {
            /*
             * 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.
             */
            inittermios.c_lflag &= ~(ECHO | ECHONL);
        }
        if (tcsetattr(fd, TCSAFLUSH, &inittermios) < 0)
            if (errno != ENXIO)
                warn("tcsetattr: %m");
        ioctl(fd, TIOCSWINSZ, &wsinfo);
        restore_term = 0;
    }
}

/*
 * setdtr - control the DTR line on the serial port.
 * This is called from die(), so it shouldn't call die().
 */
void
setdtr(fd, on)
int fd, on;
{
    int modembits = TIOCM_DTR;

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

/*
 * get_pty - get a pty master/slave pair and chown the slave side
 * to the uid given.  Assumes slave_name points to >= 12 bytes of space.
 */
int
get_pty(master_fdp, slave_fdp, slave_name, uid)
    int *master_fdp;
    int *slave_fdp;
    char *slave_name;
    int uid;
{
    struct termios tios;

    if (openpty(master_fdp, slave_fdp, slave_name, NULL, NULL) < 0)
        return 0;

    fchown(*slave_fdp, uid, -1);
    fchmod(*slave_fdp, S_IRUSR | S_IWUSR);
    if (tcgetattr(*slave_fdp, &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(*slave_fdp, TCSAFLUSH, &tios) < 0)
            warn("couldn't set attributes on pty: %m");
    } else
        warn("couldn't get attributes on pty: %m");

    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()
{
    int flags;
    struct termios tios;
    int pppdisc = PPPDISC;

    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");

    ppp_fd = loop_slave;
    if (ioctl(ppp_fd, TIOCSETD, &pppdisc) < 0)
        fatal("ioctl(TIOCSETD): %m");

    /*
     * Find out which interface we were given.
     */
    if (ioctl(ppp_fd, PPPIOCGUNIT, &ifunit) < 0)
        fatal("ioctl(PPPIOCGUNIT): %m");

    /*
     * Enable debug in the driver if requested.
     */
    if (kdebugflag) {
        if (ioctl(ppp_fd, PPPIOCGFLAGS, (caddr_t) &flags) < 0) {
            warn("ioctl (PPPIOCGFLAGS): %m");
        } else {
            flags |= (kdebugflag & 0xFF) * SC_DEBUG;
            if (ioctl(ppp_fd, PPPIOCSFLAGS, (caddr_t) &flags) < 0)
                warn("ioctl(PPPIOCSFLAGS): %m");
        }
    }

    return loop_master;
}


/*
 * 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 != EIO)
            error("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;
{
    if (fd >= FD_SETSIZE)
        fatal("internal error: file descriptor too large (%d)", 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);
}

#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);
    if (loop_master >= FD_SETSIZE)
        fatal("internal error: file descriptor too large (%d)", loop_master);
    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


/*
 * 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)
            return -1;
        fatal("read: %m");
    }
    return len;
}


/*
 * 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()
{
    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;
}


/*
 * 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(ppp_fd, PPPIOCSASYNCMAP, (caddr_t) &asyncmap) < 0)
        fatal("ioctl(PPPIOCSASYNCMAP): %m");

    if (ioctl(ppp_fd, 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;
    x = sync_serial ? x | SC_SYNC : x & ~SC_SYNC;
    if (ioctl(ppp_fd, 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(ppp_fd, PPPIOCSXASYNCMAP, accm) < 0 && errno != ENOTTY)
        warn("ioctl(set extended ACCM): %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(ppp_fd, PPPIOCSMRU, (caddr_t) &mru) < 0)
        fatal("ioctl(PPPIOCSMRU): %m");
    if (ioctl(ppp_fd, PPPIOCSRASYNCMAP, (caddr_t) &asyncmap) < 0)
        fatal("ioctl(PPPIOCSRASYNCMAP): %m");
    if (ioctl(ppp_fd, PPPIOCGFLAGS, (caddr_t) &x) < 0)
        fatal("ioctl (PPPIOCGFLAGS): %m");
    x = !accomp? x | SC_REJ_COMP_AC: x &~ SC_REJ_COMP_AC;
    if (ioctl(ppp_fd, PPPIOCSFLAGS, (caddr_t) &x) < 0)
        fatal("ioctl(PPPIOCSFLAGS): %m");
}

/*
 * ccp_test - ask kernel whether a given compression method
 * is acceptable for use.  Returns 1 if the method and parameters
 * are OK, 0 if the method is known but the parameters are not OK
 * (e.g. code size should be reduced), or -1 if the method is unknown.
 */
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(ppp_fd, 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(ppp_fd, 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(ppp_fd, PPPIOCGFLAGS, (caddr_t) &x) < 0) {
        error("ioctl(PPPIOCGFLAGS): %m");
        return 0;
    }
    return x & SC_DC_FERROR;
}

/*
 * 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_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));
    strlcpy(req.ifr_name, ifname, 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;
}


#ifdef PPP_FILTER
/*
 * set_filters - transfer the pass and active filters to the kernel.
 */
int
set_filters(pass, active)
    struct bpf_program *pass, *active;
{
    int ret = 1;

    if (pass->bf_len > 0) {
        if (ioctl(ppp_fd, PPPIOCSPASS, pass) < 0) {
            error("Couldn't set pass-filter in kernel: %m");
            ret = 0;
        }
    }
    if (active->bf_len > 0) {
        if (ioctl(ppp_fd, PPPIOCSACTIVE, active) < 0) {
            error("Couldn't set active-filter in kernel: %m");
            ret = 0;
        }
    }
    return ret;
}
#endif

/*
 * sifvjcomp - config tcp header compression
 */
int
sifvjcomp(u, vjcomp, cidcomp, maxcid)
    int u, vjcomp, cidcomp, maxcid;
{
    u_int x;

    if (ioctl(ppp_fd, PPPIOCGFLAGS, (caddr_t) &x) < 0) {
        error("ioctl (PPPIOCGFLAGS): %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(ppp_fd, PPPIOCSFLAGS, (caddr_t) &x) < 0) {
        error("ioctl(PPPIOCSFLAGS): %m");
        return 0;
    }
    if (vjcomp && ioctl(ppp_fd, PPPIOCSMAXCID, (caddr_t) &maxcid) < 0) {
        error("ioctl(PPPIOCSFLAGS): %m");
        return 0;
    }
    return 1;
}

/*
 * sifup - Config the interface up and enable IP packets to pass.
 */
int
sifup(u)
    int u;
{
    struct ifreq ifr;

    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;
    return 1;
}

/*
 * 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_fd, PPPIOCSNPMODE, &npi) < 0) {
        error("ioctl(set NP %d mode to %d): %m", proto, mode);
        return 0;
    }
    return 1;
}

/*
 * sifdown - Config the interface down and disable IP.
 */
int
sifdown(u)
    int u;
{
    struct ifreq ifr;
    int rv;
    struct npioctl npi;

    rv = 1;
    npi.protocol = PPP_IP;
    npi.mode = NPMODE_ERROR;
    ioctl(ppp_fd, PPPIOCSNPMODE, (caddr_t) &npi);
    /* ignore errors, because ppp_fd 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);                  \
    addr.sa_len = sizeof(addr);

/*
 * sifaddr - Config the interface IP addresses and netmask.
 */
int
sifaddr(u, o, h, m)
    int u;
    u_int32_t o, h, m;
{
    struct ifaliasreq ifra;
    struct ifreq ifr;

    strlcpy(ifra.ifra_name, ifname, sizeof(ifra.ifra_name));
    SET_SA_FAMILY(ifra.ifra_addr, AF_INET);
    ((struct sockaddr_in *) &ifra.ifra_addr)->sin_addr.s_addr = o;
    SET_SA_FAMILY(ifra.ifra_broadaddr, AF_INET);
    ((struct sockaddr_in *) &ifra.ifra_broadaddr)->sin_addr.s_addr = h;
    if (m != 0) {
        SET_SA_FAMILY(ifra.ifra_mask, AF_INET);
        ((struct sockaddr_in *) &ifra.ifra_mask)->sin_addr.s_addr = m;
    } else
        BZERO(&ifra.ifra_mask, sizeof(ifra.ifra_mask));
    BZERO(&ifr, sizeof(ifr));
    strlcpy(ifr.ifr_name, ifname, sizeof(ifr.ifr_name));
    if (ioctl(sockfd, SIOCDIFADDR, (caddr_t) &ifr) < 0) {
        if (errno != EADDRNOTAVAIL)
            warn("Couldn't remove interface address: %m");
    }
    if (ioctl(sockfd, SIOCAIFADDR, (caddr_t) &ifra) < 0) {
        if (errno != EEXIST) {
            error("Couldn't set interface address: %m");
            return 0;
        }
        warn("Couldn't set interface address: Address %I already exists", o);
    }
    ifaddrs[0] = o;
    ifaddrs[1] = h;
    return 1;
}

/*
 * cifaddr - Clear the interface IP addresses, and delete routes
 * through the interface if possible.
 */
int
cifaddr(u, o, h)
    int u;
    u_int32_t o, h;
{
    struct ifaliasreq ifra;

    ifaddrs[0] = 0;
    strlcpy(ifra.ifra_name, ifname, sizeof(ifra.ifra_name));
    SET_SA_FAMILY(ifra.ifra_addr, AF_INET);
    ((struct sockaddr_in *) &ifra.ifra_addr)->sin_addr.s_addr = o;
    SET_SA_FAMILY(ifra.ifra_broadaddr, AF_INET);
    ((struct sockaddr_in *) &ifra.ifra_broadaddr)->sin_addr.s_addr = h;
    BZERO(&ifra.ifra_mask, sizeof(ifra.ifra_mask));
    if (ioctl(sockfd, SIOCDIFADDR, (caddr_t) &ifra) < 0) {
        if (errno != EADDRNOTAVAIL)
            warn("Couldn't delete interface address: %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.
 */
static int
dodefaultroute(g, cmd)
    u_int32_t g;
    int cmd;
{
    int routes;
    struct {
        struct rt_msghdr        hdr;
        struct sockaddr_in      dst;
        struct sockaddr_in      gway;
        struct sockaddr_in      mask;
    } rtmsg;

    if ((routes = socket(PF_ROUTE, SOCK_RAW, AF_INET)) < 0) {
        error("Couldn't %s default route: socket: %m",
               cmd=='s'? "add": "delete");
        return 0;
    }

    memset(&rtmsg, 0, sizeof(rtmsg));
    rtmsg.hdr.rtm_type = cmd == 's'? RTM_ADD: RTM_DELETE;
    rtmsg.hdr.rtm_flags = RTF_UP | RTF_GATEWAY | RTF_STATIC;
    rtmsg.hdr.rtm_version = RTM_VERSION;
    rtmsg.hdr.rtm_seq = ++rtm_seq;
    rtmsg.hdr.rtm_addrs = RTA_DST | RTA_GATEWAY | RTA_NETMASK;
    rtmsg.dst.sin_len = sizeof(rtmsg.dst);
    rtmsg.dst.sin_family = AF_INET;
    rtmsg.gway.sin_len = sizeof(rtmsg.gway);
    rtmsg.gway.sin_family = AF_INET;
    rtmsg.gway.sin_addr.s_addr = g;
    rtmsg.mask.sin_len = sizeof(rtmsg.dst);
    rtmsg.mask.sin_family = AF_INET;

    rtmsg.hdr.rtm_msglen = sizeof(rtmsg);
    if (write(routes, &rtmsg, sizeof(rtmsg)) < 0) {
        error("Couldn't %s default route: %m",
               cmd=='s'? "add": "delete");
        close(routes);
        return 0;
    }

    close(routes);
    default_route_gateway = (cmd == 's')? g: 0;
    return 1;
}

#if RTM_VERSION >= 3

/*
 * sifproxyarp - Make a proxy ARP entry for the peer.
 */
static struct {
    struct rt_msghdr            hdr;
    struct sockaddr_inarp       dst;
    struct sockaddr_dl          hwa;
    char                        extra[128];
} arpmsg;

static int arpmsg_valid;

int
sifproxyarp(unit, hisaddr)
    int unit;
    u_int32_t hisaddr;
{
    int routes;

    /*
     * Get the hardware address of an interface on the same subnet
     * as our local address.
     */
    memset(&arpmsg, 0, sizeof(arpmsg));
    if (!get_ether_addr(hisaddr, &arpmsg.hwa)) {
        error("Cannot determine ethernet address for proxy ARP");
        return 0;
    }

    if ((routes = socket(PF_ROUTE, SOCK_RAW, AF_INET)) < 0) {
        error("Couldn't add proxy arp entry: socket: %m");
        return 0;
    }

    arpmsg.hdr.rtm_type = RTM_ADD;
    arpmsg.hdr.rtm_flags = RTF_ANNOUNCE | RTF_HOST | RTF_STATIC;
    arpmsg.hdr.rtm_version = RTM_VERSION;
    arpmsg.hdr.rtm_seq = ++rtm_seq;
    arpmsg.hdr.rtm_addrs = RTA_DST | RTA_GATEWAY;
    arpmsg.hdr.rtm_inits = RTV_EXPIRE;
    arpmsg.dst.sin_len = sizeof(struct sockaddr_inarp);
    arpmsg.dst.sin_family = AF_INET;
    arpmsg.dst.sin_addr.s_addr = hisaddr;
    arpmsg.dst.sin_other = SIN_PROXY;

    arpmsg.hdr.rtm_msglen = (char *) &arpmsg.hwa - (char *) &arpmsg
        + arpmsg.hwa.sdl_len;
    if (write(routes, &arpmsg, arpmsg.hdr.rtm_msglen) < 0) {
        error("Couldn't add proxy arp entry: %m");
        close(routes);
        return 0;
    }

    close(routes);
    arpmsg_valid = 1;
    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;
{
    int routes;

    if (!arpmsg_valid)
        return 0;
    arpmsg_valid = 0;

    arpmsg.hdr.rtm_type = RTM_DELETE;
    arpmsg.hdr.rtm_seq = ++rtm_seq;

    if ((routes = socket(PF_ROUTE, SOCK_RAW, AF_INET)) < 0) {
        error("Couldn't delete proxy arp entry: socket: %m");
        return 0;
    }

    if (write(routes, &arpmsg, arpmsg.hdr.rtm_msglen) < 0) {
        error("Couldn't delete proxy arp entry: %m");
        close(routes);
        return 0;
    }

    close(routes);
    proxy_arp_addr = 0;
    return 1;
}

#else   /* RTM_VERSION */

/*
 * sifproxyarp - Make a proxy ARP entry for the peer.
 */
int
sifproxyarp(unit, hisaddr)
    int unit;
    u_int32_t hisaddr;
{
    struct arpreq arpreq;
    struct {
        struct sockaddr_dl      sdl;
        char                    space[128];
    } dls;

    BZERO(&arpreq, sizeof(arpreq));

    /*
     * Get the hardware address of an interface on the same subnet
     * as our local address.
     */
    if (!get_ether_addr(hisaddr, &dls.sdl)) {
        error("Cannot determine ethernet address for proxy ARP");
        return 0;
    }

    arpreq.arp_ha.sa_len = sizeof(struct sockaddr);
    arpreq.arp_ha.sa_family = AF_UNSPEC;
    BCOPY(LLADDR(&dls.sdl), arpreq.arp_ha.sa_data, dls.sdl.sdl_alen);
    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("Couldn't add proxy arp entry: %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("Couldn't delete proxy arp entry: %m");
        return 0;
    }
    proxy_arp_addr = 0;
    return 1;
}
#endif  /* RTM_VERSION */


/*
 * get_ether_addr - get the hardware address of an interface on the
 * the same subnet as ipaddr.
 */
#define MAX_IFS         32

static int
get_ether_addr(ipaddr, hwaddr)
    u_int32_t ipaddr;
    struct sockaddr_dl *hwaddr;
{
    struct ifreq *ifr, *ifend, *ifp;
    u_int32_t ina, mask;
    struct sockaddr_dl *dla;
    struct ifreq ifreq;
    struct ifconf ifc;
    struct ifreq ifs[MAX_IFS];

    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 + ifr->ifr_addr.sa_len)) {
        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);

    /*
     * Now scan through again looking for a link-level address
     * for this interface.
     */
    ifp = ifr;
    for (ifr = ifc.ifc_req; ifr < ifend; ) {
        if (strcmp(ifp->ifr_name, ifr->ifr_name) == 0
            && ifr->ifr_addr.sa_family == AF_LINK) {
            /*
             * Found the link-level address - copy it out
             */
            dla = (struct sockaddr_dl *) &ifr->ifr_addr;
            BCOPY(dla, hwaddr, dla->sdl_len);
            return 1;
        }
        ifr = (struct ifreq *) ((char *)&ifr->ifr_addr + ifr->ifr_addr.sa_len);
    }

    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 + ifr->ifr_addr.sa_len)) {
        /*
         * 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;
}

/*
 * Use the hostid as part of the random number seed.
 */
int
get_host_seed()
{
    return gethostid();
}

#if 0
/*
 * lock - create a lock file for the named lock device
 */
#define LOCK_PREFIX     "/var/spool/lock/LCK.."

static char *lock_file;         /* name of lock file created */

int
lock(dev)
    char *dev;
{
    char hdb_lock_buffer[12];
    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, hdb_lock_buffer, 11);
            if (n <= 0) {
                error("Can't read pid from lock file %s", lock_file);
                close(fd);
            } else {
                hdb_lock_buffer[n] = 0;
                pid = atoi(hdb_lock_buffer);
                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;
    }

    slprintf(hdb_lock_buffer, sizeof(hdb_lock_buffer), "%10d\n", getpid());
    write(fd, hdb_lock_buffer, 11);

    close(fd);
    return 0;
}

/*
 * unlock - remove our lockfile
 */
void
unlock()
{
    if (lock_file) {
        unlink(lock_file);
        free(lock_file);
        lock_file = NULL;
    }
}
#endif