xref: /illumos-gate/usr/src/cmd/cmd-inet/usr.bin/pppd/main.c (revision 4f62a657)

/*
 * main.c - Point-to-Point Protocol main module
 *
 * Copyright 2009 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 *
 * Permission to use, copy, modify, and distribute this software and its
 * documentation is hereby granted, provided that the above copyright
 * notice appears in all copies.
 *
 * SUN MAKES NO REPRESENTATION OR WARRANTIES ABOUT THE SUITABILITY OF
 * THE SOFTWARE, EITHER EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED
 * TO THE IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
 * PARTICULAR PURPOSE, OR NON-INFRINGEMENT.  SUN SHALL NOT BE LIABLE FOR
 * ANY DAMAGES SUFFERED BY LICENSEE AS A RESULT OF USING, MODIFYING OR
 * DISTRIBUTING THIS SOFTWARE OR ITS DERIVATIVES
 *
 * 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.
 */
/*
 * Copyright (c) 2016 by Delphix. All rights reserved.
 */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <signal.h>
#include <errno.h>
#include <fcntl.h>
#include <syslog.h>
#include <netdb.h>
#include <pwd.h>
#include <setjmp.h>
#include <sys/param.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <sys/time.h>
#include <sys/resource.h>
#include <sys/stat.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>

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

#ifdef HAVE_MULTILINK
#include "tdb.h"
#endif

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

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

/* interface vars */
char ifname[32];		/* Interface name */
int ifunit = -1;		/* Interface unit number */

char *progname;			/* Name of this program */
char hostname[MAXHOSTNAMELEN+1]; /* Our hostname */
static char pidfilename[MAXPATHLEN]; /* name of pid file */
static char linkpidfile[MAXPATHLEN]; /* name of linkname pid file */
char ppp_devnam[MAXPATHLEN];	/* name of PPP tty (maybe ttypx) */
static uid_t uid;		/* Our real user-id */
static int conn_running;	/* we have a [dis]connector running */

int ttyfd;			/* Serial port file descriptor */
mode_t tty_mode = (mode_t)-1;	/* Original access permissions to tty */
int baud_rate;			/* Actual bits/second for serial device */
bool hungup;			/* terminal has been hung up */
bool privileged;		/* we're running as real uid root */
bool need_holdoff;		/* need holdoff period before restarting */
bool detached;			/* have detached from terminal */
struct stat devstat;		/* result of stat() on devnam */
bool prepass = 0;		/* doing prepass to find device name */
int devnam_fixed;		/* set while in options.ttyxx file */
volatile int status;		/* exit status for pppd */
int unsuccess;			/* # unsuccessful connection attempts */
int do_callback;		/* != 0 if we should do callback next */
int doing_callback;		/* != 0 if we are doing callback */
char *callback_script;		/* script for doing callback */
#ifdef HAVE_MULTILINK
TDB_CONTEXT *pppdb;		/* database for storing status etc. */
char db_key[32];
#endif

/*
 * For plug-in usage:
 *
 *	holdoff_hook - Can be used to change the demand-dial hold-off
 *		time dynamically.  This is normally set by the
 *		"holdoff" option, and is 30 seconds by default.
 *
 *	new_phase_hook - This is called for each change in the PPP
 *		phase (per RFC 1661).  This can be used to log
 *		progress.
 *
 *	check_options_hook - This is called before doing sys_init()
 *		and allows the plugin to verify the selected options.
 *
 *	updown_script_hook - This is called with the proposed
 *		command-line arguments for any of the
 *		/etc/ppp/{ip,ipv6,ipx,auth}-{up,down} scripts before
 *		fork/exec.  It can be used to add or change arguments.
 *
 *	device_pipe_hook - If this is set, then an extra fd (3) is
 *		passed to the connect/disconnect script.  This extra
 *		fd is the write side of a pipe, and the read side is
 *		passed to this routine.  This can be used to pass
 *		arbitrary data from the script back to pppd.
 */
int (*holdoff_hook) __P((void)) = NULL;
int (*new_phase_hook) __P((int new, int old)) = NULL;
int (*check_options_hook) __P((uid_t uid)) = NULL;
int (*updown_script_hook) __P((const char ***argsp)) = NULL;
void (*device_pipe_hook) __P((int pipefd)) = NULL;

static int fd_ppp = -1;		/* fd for talking PPP */
static int fd_loop;		/* fd for getting demand-dial packets */
static int pty_master;		/* fd for master side of pty */
int pty_slave = -1;		/* fd for slave side of pty */
static int real_ttyfd;		/* fd for actual serial port (not pty) */

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

static int waiting;		/* for input from peer or timer expiration */
static sigjmp_buf sigjmp;

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

u_char outpacket_buf[PPP_MRU+PPP_HDRLEN]; /* buffer for outgoing packet */
u_char inpacket_buf[PPP_MRU+PPP_HDRLEN]; /* buffer for incoming packet */
u_char nak_buffer[PPP_MRU];	/* where we construct a nak packet */

static int n_children;		/* # child processes still running */
static bool got_sigchld;	/* set if we have received a SIGCHLD */
static sigset_t main_sigmask;	/* signals blocked while dispatching */

static bool locked;		/* lock() has succeeded */
static bool privopen;		/* don't lock, open device as root */

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

GIDSET_TYPE groups[NGROUPS_MAX];/* groups the user is in */
int ngroups;			/* How many groups valid in groups */

static struct timeval start_time; /* Time when link was started. */

struct pppd_stats link_stats;
int link_connect_time;
bool link_stats_valid;

static pid_t charshunt_pid;	/* Process ID for charshunt */

extern option_t general_options[];
extern option_t auth_options[];

/*
 * We maintain a list of child process pids and
 * functions to call when they exit.
 */
struct subprocess {
    pid_t	pid;
    char	*prog;
    void	(*done) __P((void *, int));
    void	*arg;
    struct subprocess *next;
};

static struct subprocess *children;

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

static void setup_signals __P((void));
static void create_pidfile __P((void));
static void create_linkpidfile __P((void));
static void cleanup __P((void));
static void close_tty __P((void));
static void get_input __P((void));
static void calltimeout __P((void));
static struct timeval *timeleft __P((struct timeval *));
static void kill_my_pg __P((int));
static void hup __P((int));
static void term __P((int));
static void chld __P((int));
static void toggle_debug __P((int));
static void open_ccp __P((int));
static void bad_signal __P((int));
static void holdoff_end __P((void *));
static int device_script __P((char *, int, int, int, char *));
static int reap_kids __P((int waitfor));
static void record_child __P((pid_t, char *, void (*) (void *, int), void *));
static int open_socket __P((char *));
static int start_charshunt __P((int, int));
static void charshunt_done __P((void *, int));
static void charshunt __P((int, int, char *));
static int record_write __P((FILE *, int code, u_char *buf, int nb,
    struct timeval *));
static void final_reap __P((void));

#ifdef HAVE_MULTILINK
static void update_db_entry __P((void));
static void add_db_key __P((const char *));
static void delete_db_key __P((const char *));
static void cleanup_db __P((void));
#endif

int main __P((int, char *[]));

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

#ifdef ULTRIX
#define setlogmask(x)	0
#endif

/* Backward compatibility for Linux */
#ifndef RECMARK_TIMESTART
#define	RECMARK_STARTSEND	1
#define	RECMARK_STARTRECV	2
#define	RECMARK_ENDSEND		3
#define	RECMARK_ENDRECV		4
#define	RECMARK_TIMEDELTA32	5
#define	RECMARK_TIMEDELTA8	6
#define	RECMARK_TIMESTART	7
#endif

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

int
main(argc, argv)
    int argc;
    char *argv[];
{
    int i, fdflags, t;
    char *p, *connector;
    struct passwd *pw;
    struct timeval timo;
    struct protent *protp;
    struct stat statbuf;
    char numbuf[16];

    ifname[0] = '\0';
    new_phase(PHASE_INITIALIZE);

    /*
     * Ensure that fds 0, 1, 2 are open, to /dev/null if nowhere else.
     * This way we can close 0, 1, 2 in detach() without clobbering
     * a fd that we are using.
     */
    if ((i = open(_PATH_DEVNULL, O_RDWR)) >= 0) {
	while (0 <= i && i <= 2)
	    i = dup(i);
	if (i >= 0)
	    (void) close(i);
    }

    script_env = NULL;

    /* Initialize syslog facilities */
    reopen_log();

    if (gethostname(hostname, MAXHOSTNAMELEN+1) < 0 ) {
	option_error("Couldn't get hostname: %m");
	exit(1);
    }
    hostname[MAXHOSTNAMELEN] = '\0';

    /* make sure we don't create world or group writable files. */
    (void) umask(umask(0777) | 022);

    uid = getuid();
    privileged = (uid == 0);
    (void) slprintf(numbuf, sizeof(numbuf), "%d", uid);
    script_setenv("ORIG_UID", numbuf, 0);

    ngroups = getgroups(NGROUPS_MAX, groups);

    /*
     * Initialize magic number generator now so that protocols may
     * use magic numbers in initialization.
     */
    magic_init();

    progname = *argv;
    prepass = 0;
    /*
     * Initialize to the standard option set, then parse, in order, the
     * system options file, the user's options file, the tty's options file,
     * and the command line arguments.  At last, install the options declared
     * by each protocol into the extra_option list.
     */
    for (i = 0; (protp = protocols[i]) != NULL; ++i) {
        (*protp->init)(0);
	if (protp->options != NULL) {
	    add_options(protp->options);
	}
    }

    /*
     * Install "generic" options into the extra_options list.
     */
    add_options(auth_options);
    add_options(general_options);

    /* Install any system-specific options (or remove unusable ones) */
    sys_options();

    if (!options_from_file(_PATH_SYSOPTIONS, !privileged, 0, 1)
	|| !options_from_user())
	exit(EXIT_OPTION_ERROR);

    /* scan command line and options files to find device name */
    prepass = 1;
    (void) parse_args(argc-1, argv+1);
    prepass = 0;

    /*
     * Work out the device name, if it hasn't already been specified.
     */
    using_pty = notty || ptycommand != NULL || pty_socket != NULL;
    if (!using_pty && default_device && !direct_tty) {
	char *p;

	if (!isatty(0) || (p = ttyname(0)) == NULL) {
	    option_error("no device specified and stdin is not a tty");
	    exit(EXIT_OPTION_ERROR);
	}
	(void) strlcpy(devnam, p, sizeof(devnam));
	if (stat(devnam, &devstat) < 0)
	    fatal("Couldn't stat default device %s: %m", devnam);
    }

    /*
     * Parse the tty options file and the command line.
     * The per-tty options file should not change
     * ptycommand, pty_socket, notty or devnam.
     */
    devnam_fixed = 1;
    if (!using_pty && !direct_tty) {
	if (!options_for_tty())
	    exit(EXIT_OPTION_ERROR);
    }

    devnam_fixed = 0;
    if (!parse_args(argc-1, argv+1))
	exit(EXIT_OPTION_ERROR);

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

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

    /*
     * Check that the options given are valid and consistent.
     */
    if (!sys_check_options())
	exit(EXIT_OPTION_ERROR);
    auth_check_options();
#ifdef HAVE_MULTILINK
    mp_check_options();
#endif
    for (i = 0; (protp = protocols[i]) != NULL; ++i)
	if (protp->enabled_flag && protp->check_options != NULL)
	    (*protp->check_options)();
    if (demand && (connect_script == NULL)) {
	option_error("connect script is required for demand-dialling\n");
	exit(EXIT_OPTION_ERROR);
    }
    if (updetach && (nodetach || demand)) {
	option_error("updetach cannot be used with %s",
	    nodetach ? "nodetach" : "demand");
	exit(EXIT_OPTION_ERROR);
    }
    /* default holdoff to 0 if no connect script has been given */
    if ((connect_script == NULL) && !holdoff_specified)
	holdoff = 0;

    if (using_pty || direct_tty) {
	if (!default_device) {
	    option_error("%s option precludes specifying device name",
			 notty? "notty": "pty");
	    exit(EXIT_OPTION_ERROR);
	}
	if (ptycommand != NULL && (notty || direct_tty)) {
	    option_error("pty option is incompatible with notty option");
	    exit(EXIT_OPTION_ERROR);
	}
	if (pty_socket != NULL && (ptycommand != NULL || notty ||
	    direct_tty)) {
	    option_error("socket option is incompatible with pty and notty");
	    exit(EXIT_OPTION_ERROR);
	}
	default_device = notty || direct_tty;
	lockflag = 0;
	modem = 0;
	if (default_device && log_to_fd <= 1)
	    log_to_fd = -1;
    } else {
	/*
	 * If the user has specified a device which is the same as
	 * the one on stdin, pretend they didn't specify any.
	 * If the device is already open read/write on stdin,
	 * we assume we don't need to lock it, and we can open it as root.
	 */
	if (fstat(0, &statbuf) >= 0 && S_ISCHR(statbuf.st_mode)
	    && statbuf.st_rdev == devstat.st_rdev) {
	    default_device = 1;
	    fdflags = fcntl(0, F_GETFL);
	    if (fdflags != -1 && (fdflags & O_ACCMODE) == O_RDWR)
		privopen = 1;
	}
    }
    if (default_device)
	nodetach = 1;

    /*
     * Don't send log messages to the serial port, it tends to
     * confuse the peer. :-)
     */
    if (log_to_fd >= 0 && fstat(log_to_fd, &statbuf) >= 0
	&& S_ISCHR(statbuf.st_mode) && statbuf.st_rdev == devstat.st_rdev)
	log_to_fd = -1;
    early_log = 0;

    if (debug)
	(void) setlogmask(LOG_UPTO(LOG_DEBUG));

    /*
     * Initialize system-dependent stuff.
     */
    if (check_options_hook != NULL &&
	(*check_options_hook)(uid) == -1) {
	exit(EXIT_OPTION_ERROR);
    }
    sys_init(!devnam_info.priv && !privopen);

#ifdef HAVE_MULTILINK
    pppdb = tdb_open(_PATH_PPPDB, 0, 0, O_RDWR|O_CREAT, 0644);
    if (pppdb != NULL) {
	(void) slprintf(db_key, sizeof(db_key), "pppd%d", getpid());
	update_db_entry();
    } else {
	warn("Warning: couldn't open ppp database %s", _PATH_PPPDB);
	if (multilink) {
	    warn("Warning: disabling multilink");
	    multilink = 0;
	}
    }
#endif

    /*
     * Detach ourselves from the terminal, if required, and identify
     * who is running us.  Printing to stderr stops here unless
     * nodetach or updetach is set.
     */
    if (!nodetach && !updetach)
	detach();
    p = getlogin();
    if (p == NULL) {
	pw = getpwuid(uid);
	if (pw != NULL && pw->pw_name != NULL)
	    p = pw->pw_name;
	else
	    p = "(unknown)";
    }
    syslog(LOG_NOTICE, "pppd %s.%d%s started by %s, uid %d",
	   VERSION, PATCHLEVEL, IMPLEMENTATION, p, uid);
    script_setenv("PPPLOGNAME", p, 0);

    if (devnam[0] != '\0')
	script_setenv("DEVICE", devnam, 1);
    (void) slprintf(numbuf, sizeof(numbuf), "%d", getpid());
    script_setenv("PPPD_PID", numbuf, 1);

    setup_signals();

    waiting = 0;

    create_linkpidfile();

    /*
     * If we're doing dial-on-demand, set up the interface now.
     */
    if (demand) {
	/*
	 * Open the loopback channel and set it up to be the ppp interface.
	 */
#ifdef HAVE_MULTILINK
	(void) tdb_writelock(pppdb);
#endif
	set_ifunit(1);
	fd_loop = open_ppp_loopback();
#ifdef HAVE_MULTILINK
	(void) tdb_writeunlock(pppdb);
#endif

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

    new_phase(PHASE_INITIALIZED);
    do_callback = 0;
    for (;;) {

	need_holdoff = 1;
	ttyfd = -1;
	real_ttyfd = -1;
	status = EXIT_OK;
	++unsuccess;
	doing_callback = do_callback;
	do_callback = 0;

	if (demand && !doing_callback) {
	    /*
	     * Don't do anything until we see some activity.
	     */
	    kill_link = 0;
	    new_phase(PHASE_DORMANT);
	    demand_unblock();
	    add_fd(fd_loop);
	    for (;;) {
		if (sigsetjmp(sigjmp, 1) == 0) {
		    (void) sigprocmask(SIG_BLOCK, &main_sigmask, NULL);
		    if (kill_link || got_sigchld) {
			(void) sigprocmask(SIG_UNBLOCK, &main_sigmask, NULL);
		    } else {
			waiting = 1;
			(void) sigprocmask(SIG_UNBLOCK, &main_sigmask, NULL);
			wait_input(timeleft(&timo));
		    }
		}
		waiting = 0;
		calltimeout();
		if (kill_link) {
		    if (!persist)
			break;
		    kill_link = 0;
		}
		if (get_loop_output())
		    break;
		if (got_sigchld)
		    (void) reap_kids(0);
	    }
	    remove_fd(fd_loop);
	    if (kill_link && !persist)
		break;

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

	new_phase(doing_callback ? PHASE_CALLINGBACK : PHASE_SERIALCONN);

	/*
	 * Get a pty master/slave pair if the pty, notty, socket,
	 * or record options were specified.
	 */
	(void) strlcpy(ppp_devnam, devnam, sizeof(ppp_devnam));
	pty_master = -1;
	pty_slave = -1;
	if (using_pty || record_file != NULL) {
	    if (!get_pty(&pty_master, &pty_slave, ppp_devnam, uid)) {
		error("Couldn't allocate pseudo-tty");
		status = EXIT_FATAL_ERROR;
		goto fail;
	    }
	    set_up_tty(pty_slave, 1);
	}

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

	/*
	 * Open the serial device and set it up to be the ppp interface.
	 * First we open it in non-blocking mode so we can set the
	 * various termios flags appropriately.  If we aren't dialling
	 * out and we want to use the modem lines, we reopen it later
	 * in order to wait for the carrier detect signal from the modem.
	 */
	hungup = 0;
	kill_link = 0;
	connector = doing_callback? callback_script: connect_script;
	if (direct_tty) {
	    ttyfd = 0;
	} else if (devnam[0] != '\0') {
	    for (;;) {
		/* If the user specified the device name, become the
		   user before opening it. */
		int err;
		if (!devnam_info.priv && !privopen)
		    (void) seteuid(uid);
		if ((ttyfd = sys_extra_fd()) < 0)
		    ttyfd = open(devnam, O_NONBLOCK | O_RDWR);
		err = errno;
		if (!devnam_info.priv && !privopen)
		    (void) seteuid(0);
		if (ttyfd >= 0)
		    break;
		errno = err;
		if (err != EINTR) {
		    error("Failed to open %s: %m", devnam);
		    status = EXIT_OPEN_FAILED;
		}
		if (!persist || err != EINTR)
		    goto fail;
	    }
	    if ((fdflags = fcntl(ttyfd, F_GETFL)) == -1
		|| fcntl(ttyfd, F_SETFL, fdflags & ~O_NONBLOCK) < 0)
		warn("Couldn't reset non-blocking mode on device: %m");

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

	    /*
	     * Set line speed, flow control, etc.
	     * If we have a non-null connection or initializer script,
	     * on most systems we set CLOCAL for now so that we can talk
	     * to the modem before carrier comes up.  But this has the
	     * side effect that we might miss it if CD drops before we
	     * get to clear CLOCAL below.  On systems where we can talk
	     * successfully to the modem with CLOCAL clear and CD down,
	     * we could clear CLOCAL at this point.
	     */
	    set_up_tty(ttyfd, ((connector != NULL && connector[0] != '\0')
			       || initializer != NULL));
	    real_ttyfd = ttyfd;
	}

	/*
	 * If the pty, socket, notty and/or record option was specified,
	 * start up the character shunt now.
	 */
	status = EXIT_PTYCMD_FAILED;
	if (ptycommand != NULL) {
	    if (record_file != NULL) {
		int ipipe[2], opipe[2], ok;

		if (pipe(ipipe) < 0 || pipe(opipe) < 0)
		    fatal("Couldn't create pipes for record option: %m");
		dbglog("starting charshunt for pty option");
		ok = device_script(ptycommand, opipe[0], ipipe[1], 1,
		    "record") == 0 && start_charshunt(ipipe[0], opipe[1]);
		(void) close(ipipe[0]);
		(void) close(ipipe[1]);
		(void) close(opipe[0]);
		(void) close(opipe[1]);
		if (!ok)
		    goto fail;
	    } else {
		if (device_script(ptycommand, pty_master, pty_master, 1,
		    "pty") < 0)
		    goto fail;
		ttyfd = pty_slave;
		(void) close(pty_master);
		pty_master = -1;
	    }
	} else if (pty_socket != NULL) {
	    int fd = open_socket(pty_socket);
	    if (fd < 0)
		goto fail;
	    dbglog("starting charshunt for socket option");
	    if (!start_charshunt(fd, fd))
		goto fail;
	} else if (notty) {
	    dbglog("starting charshunt for notty option");
	    if (!start_charshunt(0, 1))
		goto fail;
	} else if (record_file != NULL) {
	    dbglog("starting charshunt for record option");
	    if (!start_charshunt(ttyfd, ttyfd))
		goto fail;
	}

	/* run connection script */
	if (((connector != NULL) && (connector[0] != '\0')) || initializer) {
	    if (real_ttyfd != -1) {
		/* XXX do this if doing_callback == CALLBACK_DIALIN? */
		if (!default_device && modem && !direct_tty) {
		    setdtr(real_ttyfd, 0);	/* in case modem is off hook */
		    (void) sleep(1);
		    setdtr(real_ttyfd, 1);
		}
	    }

	    if ((initializer != NULL) && (initializer[0] != '\0')) {
		if (device_script(initializer, ttyfd, ttyfd, 0, "init") < 0) {
		    error("Initializer script failed");
		    status = EXIT_INIT_FAILED;
		    goto fail;
		}
		if (kill_link)
		    goto disconnect;

		info("Serial port initialized.");
	    }

	    if ((connector != NULL) && (connector[0] != '\0')) {
		if (device_script(connector, ttyfd, ttyfd, 0, "connect") < 0) {
		    error("Connect script failed");
		    status = EXIT_CONNECT_FAILED;
		    goto fail;
		}
		if (kill_link)
		    goto disconnect;

		info("Serial connection established.");
	    }

	    /*
	     * Clear CLOCAL if modem option -- we now have carrier
	     * established, and we should respect loss of carrier.
	     */
	    if (real_ttyfd != -1)
		set_up_tty(real_ttyfd, 0);

	    if (doing_callback == CALLBACK_DIALIN)
		connector = NULL;
	}

	/* reopen tty if necessary to wait for carrier */
	if (connector == NULL && modem && devnam[0] != '\0' && !direct_tty) {
	    for (;;) {
		if ((i = open(devnam, O_RDWR)) >= 0)
		    break;
		if (errno != EINTR) {
		    error("Failed to reopen %s: %m", devnam);
		    status = EXIT_OPEN_FAILED;
		}
		if (!persist || errno != EINTR || hungup || kill_link)
		    goto fail;
	    }
	    (void) close(i);
	}

	(void) slprintf(numbuf, sizeof(numbuf), "%d", baud_rate);
	script_setenv("SPEED", numbuf, 0);

	/* run welcome script, if any */
	if ((welcomer != NULL) && (welcomer[0] != '\0')) {
	    if (device_script(welcomer, ttyfd, ttyfd, 0, "welcome") < 0)
		warn("Welcome script failed");
	}

	/* set up the serial device as a ppp interface */
#ifdef HAVE_MULTILINK
	(void) tdb_writelock(pppdb);
#endif
	fd_ppp = establish_ppp(ttyfd);
	if (fd_ppp < 0) {
#ifdef HAVE_MULTILINK
	    (void) tdb_writeunlock(pppdb);
#endif
	    status = EXIT_FATAL_ERROR;
	    goto disconnect;
	}

	if (!demand && ifunit >= 0)
	    set_ifunit(1);
#ifdef HAVE_MULTILINK
	(void) tdb_writeunlock(pppdb);
#endif

	/*
	 * Start opening the connection and wait for
	 * incoming events (reply, timeout, etc.).
	 */
	notice("Connect: %s <--> %s", ifname, ppp_devnam);
	(void) gettimeofday(&start_time, NULL);
	link_stats_valid = 0;
	script_unsetenv("CONNECT_TIME");
	script_unsetenv("BYTES_SENT");
	script_unsetenv("BYTES_RCVD");
	lcp_lowerup(0);

	/* Mostly for accounting purposes */
	new_phase(PHASE_CONNECTED);

	/*
	 * If we are initiating this connection, wait for a short
	 * time for something from the peer.  This can avoid bouncing
	 * our packets off its tty before it has set up the tty.
	 */
	add_fd(fd_ppp);
	if (connect_delay != 0 && (connector != NULL || ptycommand != NULL)) {
	    struct timeval t;
	    t.tv_sec = connect_delay / 1000;
	    t.tv_usec = connect_delay % 1000;
	    wait_input(&t);
	}

	lcp_open(0);		/* Start protocol */
	open_ccp_flag = 0;
	status = EXIT_NEGOTIATION_FAILED;
	new_phase(PHASE_ESTABLISH);
	while (phase != PHASE_DEAD) {
	    if (sigsetjmp(sigjmp, 1) == 0) {
		(void) sigprocmask(SIG_BLOCK, &main_sigmask, NULL);
		if (kill_link || open_ccp_flag || got_sigchld) {
		    (void) sigprocmask(SIG_UNBLOCK, &main_sigmask, NULL);
		} else {
		    waiting = 1;
		    (void) sigprocmask(SIG_UNBLOCK, &main_sigmask, NULL);
		    wait_input(timeleft(&timo));
		}
	    }
	    waiting = 0;
	    calltimeout();
	    get_input();
	    if (kill_link) {
		lcp_close(0, "User request");
		kill_link = 0;
	    }
	    if (open_ccp_flag) {
		if (phase == PHASE_NETWORK || phase == PHASE_RUNNING) {
		    /* Uncloak ourselves. */
		    ccp_fsm[0].flags &= ~OPT_SILENT;
		    (*ccp_protent.open)(0);
		}
		open_ccp_flag = 0;
	    }
	    if (got_sigchld)
		(void) reap_kids(0);	/* Don't leave dead kids lying around */
	}

	/*
	 * Print connect time and statistics.
	 */
	if (link_stats_valid) {
	    int t = (link_connect_time + 5) / 6;    /* 1/10ths of minutes */
	    info("Connect time %d.%d minutes.", t/10, t%10);
	    info("Sent %" PPP_COUNTER_F " bytes (%" PPP_COUNTER_F
		" packets), received %" PPP_COUNTER_F " bytes (%" PPP_COUNTER_F
		" packets).",
		 link_stats.bytes_out, link_stats.pkts_out,
		 link_stats.bytes_in, link_stats.pkts_in);
	}

	/*
	 * Delete pid file before disestablishing ppp.  Otherwise it
	 * can happen that another pppd gets the same unit and then
	 * we delete its pid file.
	 */
	if (!demand) {
	    if (pidfilename[0] != '\0'
		&& unlink(pidfilename) < 0 && errno != ENOENT)
		warn("unable to delete pid file %s: %m", pidfilename);
	    pidfilename[0] = '\0';
	}

	/*
	 * If we may want to bring the link up again, transfer
	 * the ppp unit back to the loopback.  Set the
	 * real serial device back to its normal mode of operation.
	 */
	remove_fd(fd_ppp);
	clean_check();
	if (demand)
	    restore_loop();
	disestablish_ppp(ttyfd);
	fd_ppp = -1;
	if (!hungup)
	    lcp_lowerdown(0);
	if (!demand)
	    script_unsetenv("IFNAME");

	/*
	 * Run disconnector script, if requested.
	 * XXX we may not be able to do this if the line has hung up!
	 */
    disconnect:
	if ((disconnect_script != NULL) && (disconnect_script[0] != '\0') &&
	    !hungup) {
	    new_phase(PHASE_DISCONNECT);
	    if (real_ttyfd >= 0)
		set_up_tty(real_ttyfd, 1);
	    if (device_script(disconnect_script, ttyfd, ttyfd, 0,
		"disconnect") < 0) {
		warn("disconnect script failed");
	    } else {
		info("Serial link disconnected.");
	    }
	}

    fail:
	if (pty_master >= 0)
	    (void) close(pty_master);
	if (pty_slave >= 0) {
	    (void) close(pty_slave);
	    pty_slave = -1;
	}
	if (real_ttyfd >= 0)
	    close_tty();
	if (locked) {
	    locked = 0;
	    unlock();
	}

	if (!demand) {
	    if (pidfilename[0] != '\0'
		&& unlink(pidfilename) < 0 && errno != ENOENT)
		warn("unable to delete pid file %s: %m", pidfilename);
	    pidfilename[0] = '\0';
	}

	if (!persist || (maxfail > 0 && unsuccess >= maxfail))
	    break;

	kill_link = 0;
	if (demand)
	    demand_discard();
	t = need_holdoff? holdoff: 0;
	if (holdoff_hook != NULL)
	    t = (*holdoff_hook)();
	if (t > 0) {
	    new_phase(PHASE_HOLDOFF);
	    TIMEOUT(holdoff_end, NULL, t);
	    do {
		if (sigsetjmp(sigjmp, 1) == 0) {
		    (void) sigprocmask(SIG_BLOCK, &main_sigmask, NULL);
		    if (kill_link || got_sigchld) {
			(void) sigprocmask(SIG_UNBLOCK, &main_sigmask, NULL);
		    } else {
			waiting = 1;
			(void) sigprocmask(SIG_UNBLOCK, &main_sigmask, NULL);
			wait_input(timeleft(&timo));
		    }
		}
		waiting = 0;
		calltimeout();
		if (kill_link) {
		    kill_link = 0;
		    new_phase(PHASE_DORMANT); /* allow signal to end holdoff */
		}
		if (got_sigchld)
		    (void) reap_kids(0);
	    } while (phase == PHASE_HOLDOFF);
	    if (!persist)
		break;
	}
    }

    /* Wait for scripts to finish */
    final_reap();

    die(status);
    return (0);
}

/*
 * setup_signals - initialize signal handling.
 */
static void
setup_signals()
{
    struct sigaction sa;

    /*
     * Compute mask of all interesting signals and install signal handlers
     * for each.  Only one signal handler may be active at a time.  Therefore,
     * all other signals should be masked when any handler is executing.
     */
    (void) sigemptyset(&main_sigmask);
    (void) sigaddset(&main_sigmask, SIGHUP);
    (void) sigaddset(&main_sigmask, SIGINT);
    (void) sigaddset(&main_sigmask, SIGTERM);
    (void) sigaddset(&main_sigmask, SIGCHLD);
    (void) sigaddset(&main_sigmask, SIGUSR2);

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

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

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

    /*
     * Install a handler for other signals which would otherwise
     * cause pppd to exit without cleaning up.
     */
/*CONSTANTCONDITION*/ SIGNAL(SIGALRM, bad_signal);
/*CONSTANTCONDITION*/ SIGNAL(SIGQUIT, bad_signal);

/* Do not hook any of these signals on Solaris; allow core dump instead */
#ifndef SOL2
/*CONSTANTCONDITION*/ SIGNAL(SIGABRT, bad_signal);
/*CONSTANTCONDITION*/ SIGNAL(SIGFPE, bad_signal);
/*CONSTANTCONDITION*/ SIGNAL(SIGILL, bad_signal);
#ifndef DEBUG
/*CONSTANTCONDITION*/ SIGNAL(SIGSEGV, bad_signal);
#endif
#ifdef SIGBUS
/*CONSTANTCONDITION*/ SIGNAL(SIGBUS, bad_signal);
#endif
#ifdef SIGEMT
/*CONSTANTCONDITION*/ SIGNAL(SIGEMT, bad_signal);
#endif
#ifdef SIGPOLL
/*CONSTANTCONDITION*/ SIGNAL(SIGPOLL, bad_signal);
#endif
#ifdef SIGPROF
/*CONSTANTCONDITION*/ SIGNAL(SIGPROF, bad_signal);
#endif
#ifdef SIGSYS
/*CONSTANTCONDITION*/ SIGNAL(SIGSYS, bad_signal);
#endif
#ifdef SIGTRAP
/*CONSTANTCONDITION*/ SIGNAL(SIGTRAP, bad_signal);
#endif
#ifdef SIGVTALRM
/*CONSTANTCONDITION*/ SIGNAL(SIGVTALRM, bad_signal);
#endif
#ifdef SIGXCPU
/*CONSTANTCONDITION*/ SIGNAL(SIGXCPU, bad_signal);
#endif
#ifdef SIGXFSZ
/*CONSTANTCONDITION*/ SIGNAL(SIGXFSZ, bad_signal);
#endif
#endif

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

/*
 * set_ifunit - do things we need to do once we know which ppp
 * unit we are using.
 */
void
set_ifunit(iskey)
    int iskey;
{
    sys_ifname();
    info("Using interface %s", ifname);
    script_setenv("IFNAME", ifname, iskey);
    if (iskey) {
	create_pidfile();	/* write pid to file */
	create_linkpidfile();
    }
}

/*
 * detach - detach us from the controlling terminal.
 */
void
detach()
{
    pid_t pid;
    char numbuf[16];

    if (detached)
	return;
    if ((pid = fork()) == (pid_t)-1) {
	error("Couldn't detach (fork failed: %m)");
	die(1);			/* or just return? */
    }
    if (pid != (pid_t)0) {
	/* parent */
	if (locked)
	    (void) relock(pid);
	exit(0);		/* parent dies */
    }
    (void) setsid();
	/*
	 * Fork again to relinquish session leadership. This is needed
	 * to prevent the daemon from acquiring controlling terminal.
	 */
    if ((pid = fork()) == (pid_t)-1) {
	error("Couldn't detach (second fork failed: %m)");
	die(1);			/* or just return? */
    }
    if (pid != (pid_t)0) {
	/* parent */
	if (locked)
	    (void) relock(pid);
	exit(0);		/* parent dies */
    }
    (void) chdir("/");
    (void) close(0);
    (void) close(1);
    (void) close(2);
    detached = 1;
    if (!log_to_file && !log_to_specific_fd)
	log_to_fd = -1;
    /* update pid files if they have been written already */
    if (pidfilename[0] != '\0')
	create_pidfile();
    if (linkpidfile[0] != '\0')
	create_linkpidfile();
    (void) slprintf(numbuf, sizeof(numbuf), "%d", getpid());
    script_setenv("PPPD_PID", numbuf, 1);
}

/*
 * reopen_log - (re)open our connection to syslog.
 */
void
reopen_log()
{
#ifdef ULTRIX
    openlog("pppd", LOG_PID);
#else
    openlog("pppd", LOG_PID | LOG_NDELAY, LOG_PPP);
    (void) setlogmask(LOG_UPTO(LOG_INFO));
#endif
}