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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) 1989 Carnegie Mellon University.
 * Copyright (c) 1995 The Australian National 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 and The Australian National University.
 * The names of the Universities may not be used to endorse or promote
 * products derived from this software without specific prior written
 * permission.
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
 * WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
 */

#ifndef lint
static char rcsid[] = "$FreeBSD: src/usr.sbin/pppd/sys-bsd.c,v 1.21.6.1 2008/11/25 02:59:29 kensmith Exp $";
#endif
/*    $NetBSD: sys-bsd.c,v 1.1.1.3 1997/09/26 18:53:04 christos Exp $   */

/*
 * TODO:
 */

#include <stdio.h>
#include <syslog.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>
#include <sys/module.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>
#include <net/if_var.h>
#include <netinet6/in6_var.h>
#include <netinet6/nd6.h>
#include <ifaddrs.h>

#ifdef IPX_CHANGE
#include <netipx/ipx.h>
#endif

#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 <ifaddrs.h>

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

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

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 */
#ifdef INET6
static int sock6_fd = -1;     /* socket for doing ipv6 interface ioctls */
#endif /* INET6 */

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) {
      syslog(LOG_ERR, "Couldn't create IP socket: %m");
      die(1);
    }

#ifdef INET6
    if ((sock6_fd = socket(AF_INET6, SOCK_DGRAM, 0)) < 0) {
      /* check it at runtime */
      sock6_fd = -1;
    }
#endif
}

/*
 * 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) {
      strncpy(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()
{
    if (sockfd >= 0)
      close(sockfd);
#ifdef INET6
    if (sock6_fd >= 0)
      close(sock6_fd);
#endif
    if (loop_slave >= 0) {
      close(loop_slave);
      close(loop_master);
    }
}

/*
 * sys_check_options - check the options that the user specified
 */
void
sys_check_options()
{
}

/*
 * ppp_available - check whether the system has the ppp module loaded
 * or compiled in. If it doesn't, and we're actually root (not just SUID
 * root) try loading it before giving up.
 */
int
ppp_available()
{
    const char *modname = "if_ppp";
    extern char *no_ppp_msg;

    if (modfind(modname) != -1) {
      return 1;
    }

    if (getuid() == 0 && kldload(modname) != -1)
      return 1;

    no_ppp_msg = "\
This system lacks kernel support for PPP.  To include PPP support\n\
in the kernel, please add \"device ppp\" to your kernel config or \n\
load the if_ppp module.\n";

    return 0;
}

/*
 * establish_ppp - Turn the serial port into a ppp interface.
 */
void
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) {
          syslog(LOG_ERR, "ioctl(transfer ppp unit): %m");
          die(1);
      }
    }

    /*
     * Save the old line discipline of fd, and set it to PPP.
     */
    if (ioctl(fd, TIOCGETD, &initdisc) < 0) {
      syslog(LOG_ERR, "ioctl(TIOCGETD): %m");
      die(1);
    }
    if (ioctl(fd, TIOCSETD, &pppdisc) < 0) {
      syslog(LOG_ERR, "ioctl(TIOCSETD): %m");
      die(1);
    }

    if (!demand) {
      /*
       * Find out which interface we were given.
       */
      if (ioctl(fd, PPPIOCGUNIT, &ifunit) < 0) {      
          syslog(LOG_ERR, "ioctl(PPPIOCGUNIT): %m");
          die(1);
      }
    } else {
      /*
       * Check that we got the same unit again.
       */
      if (ioctl(fd, PPPIOCGUNIT, &x) < 0) {     
          syslog(LOG_ERR, "ioctl(PPPIOCGUNIT): %m");
          die(1);
      }
      if (x != ifunit) {
          syslog(LOG_ERR, "transfer_ppp failed: wanted unit %d, got %d",
               ifunit, x);
          die(1);
      }
      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) {
          syslog(LOG_WARNING, "ioctl (PPPIOCGFLAGS): %m");
      } else {
          x |= (kdebugflag & 0xFF) * SC_DEBUG;
          if (ioctl(fd, PPPIOCSFLAGS, (caddr_t) &x) < 0)
            syslog(LOG_WARNING, "ioctl(PPPIOCSFLAGS): %m");
      }
    }

    /*
     * Set device for non-blocking reads.
     */
    if ((initfdflags = fcntl(fd, F_GETFL)) == -1
      || fcntl(fd, F_SETFL, initfdflags | O_NONBLOCK) == -1) {
      syslog(LOG_WARNING, "Couldn't set device to non-blocking mode: %m");
    }
}

/*
 * 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) {
      syslog(LOG_ERR, "ioctl(transfer ppp unit): %m");
      die(1);
    }
    x = PPPDISC;
    if (ioctl(loop_slave, TIOCSETD, &x) < 0) {
      syslog(LOG_ERR, "ioctl(TIOCSETD): %m");
      die(1);
    }

    /*
     * Check that we got the same unit again.
     */
    if (ioctl(loop_slave, PPPIOCGUNIT, &x) < 0) {     
      syslog(LOG_ERR, "ioctl(PPPIOCGUNIT): %m");
      die(1);
    }
    if (x != ifunit) {
      syslog(LOG_ERR, "transfer_ppp failed: wanted unit %d, got %d",
             ifunit, x);
      die(1);
    }
    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)
      syslog(LOG_WARNING, "Couldn't restore device fd flags: %m");
    initfdflags = -1;

    /* Restore old line discipline. */
    if (initdisc >= 0 && ioctl(fd, TIOCSETD, &initdisc) < 0)
      syslog(LOG_ERR, "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) {
          syslog(LOG_WARNING, "Serial link is not 8-bit clean:");
          syslog(LOG_WARNING, "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) {
      syslog(LOG_ERR, "tcgetattr: %m");
      die(1);
    }

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

    tios.c_cflag &= ~(CSIZE | CSTOPB | PARENB | CLOCAL);
    if (crtscts > 0 && !local)
      tios.c_cflag |= CRTSCTS;
    else if (crtscts < 0)
      tios.c_cflag &= ~CRTSCTS;

    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) {
          syslog(LOG_ERR, "Baud rate for %s is 0; need explicit baud rate",
               devnam);
          die(1);
      }
    }
    baud_rate = inspeed;

    if (tcsetattr(fd, TCSAFLUSH, &tios) < 0) {
      syslog(LOG_ERR, "tcsetattr: %m");
      die(1);
    }

    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)
            syslog(LOG_WARNING, "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);
}

#ifdef INET6
/*
 * sif6addr - Config the interface with an IPv6 link-local address
 */
int
sif6addr(int unit, eui64_t our_eui64, eui64_t his_eui64)
{
    int ifindex;
    struct in6_aliasreq addreq6;

    if (sock6_fd < 0) {
      syslog(LOG_ERR, "No IPv6 socket available");
      die(1);
      /*NOTREACHED*/
    }

    /* actually, this part is not kame local - RFC2553 conformant */
    ifindex = if_nametoindex(ifname);
    if (ifindex == 0) {
      syslog(LOG_ERR, "sifaddr6: no interface %s", ifname);
      return 0;
    }

    memset(&addreq6, 0, sizeof(addreq6));
    strlcpy(addreq6.ifra_name, ifname, sizeof(addreq6.ifra_name));

    /* my addr */
    addreq6.ifra_addr.sin6_family = AF_INET6;
    addreq6.ifra_addr.sin6_len = sizeof(struct sockaddr_in6);
    addreq6.ifra_addr.sin6_addr.s6_addr[0] = 0xfe;
    addreq6.ifra_addr.sin6_addr.s6_addr[1] = 0x80;
    memcpy(&addreq6.ifra_addr.sin6_addr.s6_addr[8], &our_eui64,
      sizeof(our_eui64));
    /* KAME ifindex hack */
    *(u_int16_t *)&addreq6.ifra_addr.sin6_addr.s6_addr[2] = htons(ifindex);

    /* his addr */
    addreq6.ifra_dstaddr.sin6_family = AF_INET6;
    addreq6.ifra_dstaddr.sin6_len = sizeof(struct sockaddr_in6);
    addreq6.ifra_dstaddr.sin6_addr.s6_addr[0] = 0xfe;
    addreq6.ifra_dstaddr.sin6_addr.s6_addr[1] = 0x80;
    memcpy(&addreq6.ifra_dstaddr.sin6_addr.s6_addr[8], &his_eui64,
      sizeof(our_eui64));
    /* KAME ifindex hack */
    *(u_int16_t *)&addreq6.ifra_dstaddr.sin6_addr.s6_addr[2] = htons(ifindex);

    /* prefix mask: 128bit */
    addreq6.ifra_prefixmask.sin6_family = AF_INET6;
    addreq6.ifra_prefixmask.sin6_len = sizeof(struct sockaddr_in6);
    memset(&addreq6.ifra_prefixmask.sin6_addr, 0xff,
      sizeof(addreq6.ifra_prefixmask.sin6_addr));

    /* address lifetime (infty) */
    addreq6.ifra_lifetime.ia6t_pltime = ND6_INFINITE_LIFETIME;
    addreq6.ifra_lifetime.ia6t_vltime = ND6_INFINITE_LIFETIME;

    if (ioctl(sock6_fd, SIOCAIFADDR_IN6, &addreq6) < 0) {
      syslog(LOG_ERR, "sif6addr: ioctl(SIOCAIFADDR_IN6): %m");
      return 0;
    }

    return 1;
}


/*
 * cif6addr - Remove IPv6 address from interface
 */
int
cif6addr(int unit, eui64_t our_eui64, eui64_t his_eui64)
{
    int ifindex;
    struct in6_ifreq delreq6;

    if (sock6_fd < 0) {
      syslog(LOG_ERR, "No IPv6 socket available");
      die(1);
      /*NOTREACHED*/
    }

    /* actually, this part is not kame local - RFC2553 conformant */
    ifindex = if_nametoindex(ifname);
    if (ifindex == 0) {
      syslog(LOG_ERR, "cifaddr6: no interface %s", ifname);
      return 0;
    }

    memset(&delreq6, 0, sizeof(delreq6));
    strlcpy(delreq6.ifr_name, ifname, sizeof(delreq6.ifr_name));

    /* my addr */
    delreq6.ifr_ifru.ifru_addr.sin6_family = AF_INET6;
    delreq6.ifr_ifru.ifru_addr.sin6_len = sizeof(struct sockaddr_in6);
    delreq6.ifr_ifru.ifru_addr.sin6_addr.s6_addr[0] = 0xfe;
    delreq6.ifr_ifru.ifru_addr.sin6_addr.s6_addr[1] = 0x80;
    memcpy(&delreq6.ifr_ifru.ifru_addr.sin6_addr.s6_addr[8], &our_eui64,
      sizeof(our_eui64));
    /* KAME ifindex hack */
    *(u_int16_t *)&delreq6.ifr_ifru.ifru_addr.sin6_addr.s6_addr[2] =
      htons(ifindex);

    if (ioctl(sock6_fd, SIOCDIFADDR_IN6, &delreq6) < 0) {
      syslog(LOG_ERR, "cif6addr: ioctl(SIOCDIFADDR_IN6): %m");
      return 0;
    }

    return 1;
}
#endif /* INET6 */

/*
 * 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.
 */
void
open_ppp_loopback()
{
    int flags;
    struct termios tios;
    int pppdisc = PPPDISC;

    if (openpty(&loop_master, &loop_slave, loop_name, NULL, NULL) < 0) {
      syslog(LOG_ERR, "No free pty for loopback");
      die(1);
    }
    SYSDEBUG((LOG_DEBUG, "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)
          syslog(LOG_WARNING, "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)
          syslog(LOG_WARNING, "couldn't set loopback to nonblock: %m");

    ppp_fd = loop_slave;
    if (ioctl(ppp_fd, TIOCSETD, &pppdisc) < 0) {
      syslog(LOG_ERR, "ioctl(TIOCSETD): %m");
      die(1);
    }

    /*
     * Find out which interface we were given.
     */
    if (ioctl(ppp_fd, PPPIOCGUNIT, &ifunit) < 0) {    
      syslog(LOG_ERR, "ioctl(PPPIOCGUNIT): %m");
      die(1);
    }

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

}


/*
 * output - Output PPP packet.
 */
void
output(unit, p, len)
    int unit;
    u_char *p;
    int len;
{
    if (debug)
      log_packet(p, len, "sent ", LOG_DEBUG);

    if (write(ttyfd, p, len) < 0) {
      if (errno != EIO)
          syslog(LOG_ERR, "write: %m");
    }
}


/*
 * wait_input - wait until there is data available on ttyfd,
 * 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;

    if (ttyfd >= FD_SETSIZE) {
          syslog(LOG_ERR, "descriptor too big");
          die(1);
    }
    FD_ZERO(&ready);
    FD_SET(ttyfd, &ready);
    n = select(ttyfd+1, &ready, NULL, &ready, timo);
    if (n < 0 && errno != EINTR) {
      syslog(LOG_ERR, "select: %m");
      die(1);
    }
}


/*
 * 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;

    if (loop_master >= FD_SETSIZE) {
          syslog(LOG_ERR, "descriptor too big");
          die(1);
    }
    FD_ZERO(&ready);
    FD_SET(loop_master, &ready);
    n = select(loop_master + 1, &ready, NULL, &ready, timo);
    if (n < 0 && errno != EINTR) {
      syslog(LOG_ERR, "select: %m");
      die(1);
    }
}


/*
 * 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) {
      syslog(LOG_ERR, "select: %m");
      die(1);
    }
}


/*
 * 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;
      syslog(LOG_ERR, "read: %m");
      die(1);
    }
    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) {
      syslog(LOG_ERR, "eof on loopback");
      die(1);
    } else if (errno != EWOULDBLOCK){
      syslog(LOG_ERR, "read from loopback: %m");
      die(1);
    }

    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;

    strncpy(ifr.ifr_name, ifname, sizeof (ifr.ifr_name));
    ifr.ifr_mtu = mtu;
    if (ioctl(sockfd, SIOCSIFMTU, (caddr_t) &ifr) < 0) {
      syslog(LOG_ERR, "ioctl(SIOCSIFMTU): %m");
      quit();
    }

    if (ioctl(ppp_fd, PPPIOCSASYNCMAP, (caddr_t) &asyncmap) < 0) {
      syslog(LOG_ERR, "ioctl(PPPIOCSASYNCMAP): %m");
      quit();
    }

    if (ioctl(ppp_fd, PPPIOCGFLAGS, (caddr_t) &x) < 0) {
      syslog(LOG_ERR, "ioctl (PPPIOCGFLAGS): %m");
      quit();
    }
    x = pcomp? x | SC_COMP_PROT: x &~ SC_COMP_PROT;
    x = accomp? x | SC_COMP_AC: x &~ SC_COMP_AC;
    if (ioctl(ppp_fd, PPPIOCSFLAGS, (caddr_t) &x) < 0) {
      syslog(LOG_ERR, "ioctl(PPPIOCSFLAGS): %m");
      quit();
    }
}


/*
 * 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)
      syslog(LOG_WARNING, "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) {
      syslog(LOG_ERR, "ioctl(PPPIOCSMRU): %m");
      quit();
    }
    if (ioctl(ppp_fd, PPPIOCSRASYNCMAP, (caddr_t) &asyncmap) < 0) {
      syslog(LOG_ERR, "ioctl(PPPIOCSRASYNCMAP): %m");
      quit();
    }
    if (ioctl(ppp_fd, PPPIOCGFLAGS, (caddr_t) &x) < 0) {
      syslog(LOG_ERR, "ioctl (PPPIOCGFLAGS): %m");
      quit();
    }
    x = !accomp? x | SC_REJ_COMP_AC: x &~ SC_REJ_COMP_AC;
    if (ioctl(ppp_fd, PPPIOCSFLAGS, (caddr_t) &x) < 0) {
      syslog(LOG_ERR, "ioctl(PPPIOCSFLAGS): %m");
      quit();
    }
}

/*
 * 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) {
      syslog(LOG_ERR, "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)
      syslog(LOG_ERR, "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) {
      syslog(LOG_ERR, "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;
}


#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) {
          syslog(LOG_ERR, "Couldn't set pass-filter in kernel: %m");
          ret = 0;
      }
    }
    if (active->bf_len > 0) {
      if (ioctl(ppp_fd, PPPIOCSACTIVE, active) < 0) {
          syslog(LOG_ERR, "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) {
      syslog(LOG_ERR, "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) {
      syslog(LOG_ERR, "ioctl(PPPIOCSFLAGS): %m");
      return 0;
    }
    if (vjcomp && ioctl(ppp_fd, PPPIOCSMAXCID, (caddr_t) &maxcid) < 0) {
      syslog(LOG_ERR, "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;

    strncpy(ifr.ifr_name, ifname, sizeof (ifr.ifr_name));
    if (ioctl(sockfd, SIOCGIFFLAGS, (caddr_t) &ifr) < 0) {
      syslog(LOG_ERR, "ioctl (SIOCGIFFLAGS): %m");
      return 0;
    }
    ifr.ifr_flags |= IFF_UP;
    if (ioctl(sockfd, SIOCSIFFLAGS, (caddr_t) &ifr) < 0) {
      syslog(LOG_ERR, "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) {
      syslog(LOG_ERR, "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. */

    strncpy(ifr.ifr_name, ifname, sizeof (ifr.ifr_name));
    if (ioctl(sockfd, SIOCGIFFLAGS, (caddr_t) &ifr) < 0) {
      syslog(LOG_ERR, "ioctl (SIOCGIFFLAGS): %m");
      rv = 0;
    } else {
      ifr.ifr_flags &= ~IFF_UP;
      if (ioctl(sockfd, SIOCSIFFLAGS, (caddr_t) &ifr) < 0) {
          syslog(LOG_ERR, "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;

    strncpy(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));
    strncpy(ifr.ifr_name, ifname, sizeof(ifr.ifr_name));
    if (ioctl(sockfd, SIOCDIFADDR, (caddr_t) &ifr) < 0) {
      if (errno != EADDRNOTAVAIL)
          syslog(LOG_WARNING, "Couldn't remove interface address: %m");
    }
    if (ioctl(sockfd, SIOCAIFADDR, (caddr_t) &ifra) < 0) {
      if (errno != EEXIST) {
          syslog(LOG_ERR, "Couldn't set interface address: %m");
          return 0;
      }
      syslog(LOG_WARNING,
             "Couldn't set interface address: Address %s already exists",
            ip_ntoa(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;
    strncpy(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)
          syslog(LOG_WARNING, "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) {
      syslog(LOG_ERR, "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) {
      syslog(LOG_ERR, "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)) {
      syslog(LOG_ERR, "Cannot determine ethernet address for proxy ARP");
      return 0;
    }

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

    if (write(routes, &arpmsg, arpmsg.hdr.rtm_msglen) < 0) {
      syslog(LOG_ERR, "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)) {
      syslog(LOG_ERR, "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) {
      syslog(LOG_ERR, "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) {
      syslog(LOG_WARNING, "Couldn't delete proxy arp entry: %m");
      return 0;
    }
    proxy_arp_addr = 0;
    return 1;
}
#endif      /* RTM_VERSION */

#ifdef IPX_CHANGE
/********************************************************************
 *
 * sipxfaddr - Config the interface IPX networknumber
 */

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

    int    skfd; 
    struct sockaddr_ipx  ipx_addr;
    struct ifreq         ifr;
    struct sockaddr_ipx *sipx = (struct sockaddr_ipx *) &ifr.ifr_addr;
    union ipx_net_u net;

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

      memcpy (sipx->sipx_addr.x_host.c_host, node, 6);
      sipx->sipx_len     = sizeof(sipx);
      sipx->sipx_family  = AF_IPX;
      sipx->sipx_port    = 0;
      memset(&net, 0, sizeof(net));
      net.long_e = htonl (network);
      sipx->sipx_addr.x_net = net.net_e;
/*
 *  Set the IPX device
 */
      if (ioctl(skfd, SIOCSIFADDR, (caddr_t) &ifr) < 0)
        {
          result = 0;
          if (errno != EEXIST)
            {
            syslog (LOG_DEBUG,
                      "ioctl(SIOCAIFADDR, CRTITF): %m(%d)", errno);
            }
          else
            {
            syslog (LOG_WARNING,
                  "ioctl(SIOCAIFADDR, CRTITF): Address already exists");
            }
        }
      close (skfd);
      }
    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;

    int    skfd; 
    struct sockaddr_ipx  ipx_addr;
    struct ifreq         ifr;
    struct sockaddr_ipx *sipx = (struct sockaddr_ipx *) &ifr.ifr_addr;

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

      sipx->sipx_len     = sizeof(sipx);
      sipx->sipx_family  = AF_IPX;
/*
 *  Set the IPX device
 */
      if (ioctl(skfd, SIOCSIFADDR, (caddr_t) &ifr) < 0)
        {
          syslog (LOG_INFO,
                  "ioctl(SIOCAIFADDR, IPX_DLTITF): %m(%d)", errno);
          result = 0;
        }
      close (skfd);
      }
    return result;
  }
#endif

/*
 * get_ether_addr - get the hardware address of an interface on the
 * the same subnet as ipaddr.
 */
static int
get_ether_addr(ipaddr, hwaddr)
    u_int32_t ipaddr;
    struct sockaddr_dl *hwaddr;
{
    u_int32_t ina, mask;
    struct sockaddr_dl *dla;
    struct ifaddrs *ifap, *ifa, *ifp;

    /*
     * Scan through looking for an interface with an Internet
     * address on the same subnet as `ipaddr'.
     */
    if (getifaddrs(&ifap) != 0) {
      syslog(LOG_ERR, "getifaddrs: %m");
      return 0;
    }
    for (ifa = ifap; ifa; ifa = ifa->ifa_next) {
      if (ifa->ifa_addr->sa_family != AF_INET)
          continue;
      ina = ((struct sockaddr_in *) ifa->ifa_addr)->sin_addr.s_addr;
      /*
       * Check that the interface is up, and not point-to-point
       * or loopback.
       */
      if ((ifa->ifa_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.
       */
      mask = ((struct sockaddr_in *) ifa->ifa_netmask)->sin_addr.s_addr;
      if ((ipaddr & mask) != (ina & mask))
            continue;
      break;
    }
    if (!ifa) {
      freeifaddrs(ifap);
      return 0;
    }
    syslog(LOG_INFO, "found interface %s for proxy arp", ifa->ifa_name);

    /*
     * Now scan through again looking for a link-level address
     * for this interface.
     */
    ifp = ifa;
    for (ifa = ifap; ifa; ifa = ifa->ifa_next) {
      if (strcmp(ifp->ifa_name, ifa->ifa_name) != 0)
          continue;
      if (ifa->ifa_addr->sa_family != AF_LINK)
          continue;
      /*
       * Found the link-level address - copy it out
       */
      dla = (struct sockaddr_dl *) ifa->ifa_addr;
      BCOPY(dla, hwaddr, dla->sdl_len);
      freeifaddrs(ifap);
      return 1;
    }

    freeifaddrs(ifap);
    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 ifaddrs *ifap, *ifa;

    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.
     */
    if (getifaddrs(&ifap) != 0) {
      syslog(LOG_WARNING, "getifaddrs: %m");
      return mask;
    }
    for (ifa = ifap; ifa; ifa = ifa->ifa_next) {
      /*
       * Check the interface's internet address.
       */
      if (ifa->ifa_addr->sa_family != AF_INET)
          continue;
      ina = ((struct sockaddr_in *)&ifa->ifa_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.
       */
      if ((ifa->ifa_flags & (IFF_UP|IFF_POINTOPOINT|IFF_LOOPBACK)) != IFF_UP)
          continue;
      /*
       * Get its netmask and OR it into our mask.
       */
      mask |= ((struct sockaddr_in *)&ifa->ifa_netmask)->sin_addr.s_addr;
    }

    freeifaddrs(ifap);
    return mask;
}

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

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

int
lock(dev)
    char *dev;
{
    char hdb_lock_buffer[12];
    int fd, pid, n;
    char *p;

    if ((p = strrchr(dev, '/')) != NULL)
      dev = p + 1;
    lock_file = malloc(strlen(LOCK_PREFIX) + strlen(dev) + 1);
    if (lock_file == NULL)
      novm("lock file name");
    strcat(strcpy(lock_file, 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) {
            syslog(LOG_ERR, "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);
                  syslog(LOG_NOTICE, "Removed stale lock on %s (pid %d)",
                         dev, pid);
                  continue;
                } else
                  syslog(LOG_WARNING, "Couldn't remove stale lock on %s",
                         dev);
            } else
                syslog(LOG_NOTICE, "Device %s is locked by pid %d",
                     dev, pid);
          }
          close(fd);
      } else
          syslog(LOG_ERR, "Can't create lock file %s: %m", lock_file);
      free(lock_file);
      lock_file = NULL;
      return -1;
    }

    sprintf(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;
    }
}

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