/*
 * Copyright (c) 1988 Regents of the University of California.
 * All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * Rick Adams.
 *
 * 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. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *	This product includes software developed by the University of
 *	California, Berkeley and its contributors.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

/*
 * Hacks to support "-a|c|n" flags on the command line which enable VJ
 * header compresion and disable ICMP.
 * If this is good all rights go to B & L Jolitz, otherwise send your
 * comments to Reagan (/dev/null).
 *
 * nerd@percival.rain.com (Michael Galassi) 92.09.03
 *
 * Hacked to change from sgtty to POSIX termio style serial line control
 * and added flag to enable cts/rts style flow control.
 *
 * blymn@awadi.com.au (Brett Lymn) 93.04.04
 *
 * Put slattach in it's own process group so it can't be killed
 * accidentally. Close the connection on SIGHUP and SIGINT. Write a
 * syslog entry upon opening and closing the connection.  Rich Murphey
 * and Brad Huntting.
 *
 * Add '-r command' option: runs 'command' upon recieving SIGHUP
 * resulting from loss of carrier.  Log any errors after forking.
 * Rich 8/13/93
 *
 * This version of slattach includes many changes by David Greenman, Brian
 * Smith, Chris Bradley, and me (Michael Galassi).  None of them are
 * represented as functional anywhere outside of RAINet though they do work
 * for us.  Documentation is limited to the usage message for now.  If you
 * make improovments please pass them back.
 *
 * Added '-u UCMD' which runs 'UCMD <old> <new>' whenever the slip
 * unit number changes where <old> and <new> are the old and new unit
 * numbers, respectively.  Also added the '-z' option which forces
 * invocation of the redial command (-r CMD) upon startup regardless
 * of whether the com driver claims (sometimes mistakenly) that
 * carrier is present. Also added '-e ECMD' which runs ECMD before
 * exiting.
 *
 * marc@escargot.rain.com (Marc Frajola) 93/09/10
 *
 * Minor fixes to allow passive SLIP links to work (connections with
 * modem control that do not have an associated dial command). Added
 * code to re-check for carrier after dial command has been executed.
 * Added SIGTERM handler to properly handle normal kill signals. Fixed
 * bug in logic that caused message about no -u command to be logged
 * even when -u was specified and the sl number changes. Tried to get
 * rid of redundant syslog()'s to minimize console log output. Improved
 * logging of improper command line options or number of command
 * arguments. Removed spurious newline characters from syslog() calls.
 *
 * gjung@gjbsd.franken.de
 *
 * sighup_handler changed to set CLOCAL before running redial_cmd.
 * added flag exiting, so exit_handler is not run twice.
 *
 */

#ifndef lint
char copyright[] =
"@(#) Copyright (c) 1988 Regents of the University of California.\n\
 All rights reserved.\n";
#endif /* not lint */

#ifndef lint
/*static char sccsid[] = "from: @(#)slattach.c	4.6 (Berkeley) 6/1/90";*/
static char rcsid[] = "$Id";
#endif /* not lint */

#include <sys/param.h>
#include <sys/ioctl.h>
#include <termios.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <net/if.h>
#include <net/if_slvar.h>
#include <netdb.h>
#include <fcntl.h>
#include <stdlib.h>
#include <stdio.h>
#include <unistd.h>
#include <paths.h>
#include <syslog.h>
#include <signal.h>
#include <strings.h>

extern int errno;
extern char *sys_errlist[];

#define DEFAULT_BAUD	9600

void	sighup_handler();	/* SIGHUP handler */
void	sigint_handler();	/* SIGINT handler */
void	sigterm_handler();	/* SIGTERM handler */
void	exit_handler(int ret);	/* run exit_cmd iff specified upon exit. */
void	setup_line();		/* configure slip line */
void	attach_line();		/* switch to slip line discipline */

int	fd = -1;
char	*dev = (char *)0;
int	slipdisc = SLIPDISC;
int	ttydisc = TTYDISC;
int	flow_control = 0;	/* non-zero to enable hardware flow control. */
int	modem_control = 0;	/* non-zero iff we watch carrier. */
int	comstate;		/* TIOCMGET current state of serial driver */
int	redial_on_startup = 0;	/* iff non-zero execute redial_cmd on startup */
int	speed = DEFAULT_BAUD;
int	slflags = 0;		/* compression flags */
int	unit = -1;		/* slip device unit number */
int	foreground = 0;
int	exiting = 0;		/* allready running exit_handler */
FILE	*console;

struct	termios tty;
struct	termios tty_orig;	/* For saving original tty state */

char	devname[32];
char	hostname[MAXHOSTNAMELEN];
char	*redial_cmd = 0;	/* command to exec upon shutdown. */
char	*config_cmd = 0;	/* command to exec if slip unit changes. */
char	*exit_cmd = 0;		/* command to exec before exiting. */
char	string[100];

static char usage_str[] = "\
usage: %s [-acfhlnz] [-e command] [-r command] [-s speed] [-u command] device\n\
  -a      -- autoenable VJ compression\n\
  -c      -- enable VJ compression\n\
  -e ECMD -- run ECMD before exiting\n\
  -f      -- run in foreground (don't detach from controlling tty)\n\
  -h      -- turn on cts/rts style flow control\n\
  -l      -- disable modem control (CLOCAL) and ignore carrier detect\n\
  -n      -- throw out ICMP packets\n\
  -r RCMD -- run RCMD upon loss of carrier\n\
  -s #    -- set baud rate (default 9600)\n\
  -u UCMD -- run 'UCMD <old sl#> <new sl#>' before switch to slip discipline\n\
  -z      -- run RCMD upon startup irrespective of carrier\n";

int main(int argc, char **argv)
{
	int option;
	char name[32];
	extern char *optarg;
	extern int optind;

	while ((option = getopt(argc, argv, "ace:fhlnr:s:u:z")) != EOF) {
		switch (option) {
		case 'a':
			slflags |= SC_AUTOCOMP;
			slflags &= ~SC_COMPRESS;
			break;
		case 'c':
			slflags |= SC_COMPRESS;
			slflags &= ~SC_AUTOCOMP;
			break;
		case 'e':
			exit_cmd = (char*) strdup (optarg);
			break;
		case 'f':
			foreground = 1;
			break;
		case 'h':
			flow_control |= CRTSCTS;
			break;
		case 'l':
			modem_control |= CLOCAL;
			break;
		case 'n':
			slflags |= SC_NOICMP;
			break;
		case 'r':
			redial_cmd = (char*) strdup (optarg);
			break;
		case 's':
			speed = atoi(optarg);
			break;
		case 'u':
			config_cmd = (char*) strdup (optarg);
			break;
		case 'z':
			redial_on_startup = 1;
			break;
		default:
			fprintf(stderr, "%s: Invalid option -- '%c'\n",
			  option);
		case '?':
			fprintf(stderr, usage_str, argv[0]);
			exit_handler(1);
		}
	}

	if (optind == argc - 1)
		dev = argv[optind];

	if (optind < (argc - 1)) {
	    fprintf(stderr, "%s: Too many args, first='%s'\n",
	      argv[0], argv[optind]);
	}
	if (optind > (argc - 1)) {
	    fprintf(stderr, "%s: Not enough args\n", argv[0]);
	}
	if (dev == (char *)0) {
		fprintf(stderr, usage_str, argv[0]);
		exit_handler(2);
	}
	if (strncmp(_PATH_DEV, dev, sizeof(_PATH_DEV) - 1)) {
		strcpy(devname, _PATH_DEV);
		strcat(devname, "/");
		strncat(devname, dev, 10);
		dev = devname;
	}

	if (!foreground)
		daemon(0,0);	/* fork, setsid, chdir /, and close std*. */

	/* Note: daemon() closes stderr, so log errors from here on. */
	(void)sprintf(name,"slattach[%d]", getpid());
	openlog(name,LOG_CONS,LOG_DAEMON);

	if ((fd = open(dev, O_RDWR | O_NONBLOCK)) < 0) {
                syslog(LOG_ERR, "open(%s): %m", dev);
		exit_handler(1);
	}
	/* acquire the serial line as a controling terminal. */
	if (ioctl(fd, TIOCSCTTY, 0) < 0)
		syslog(LOG_NOTICE,"ioctl(TIOCSCTTY) failed: %s: %m");
	/* Make us the foreground process group associated with the
	   slip line which is our controlling terminal. */
	if (tcsetpgrp(fd, getpid()) < 0)
		syslog(LOG_NOTICE,"tcsetpgrp failed: %s: %m");
	/* upon INT log a timestamp and exit.  */
	if ((int)signal(SIGINT,sigint_handler) < 0)
		syslog(LOG_NOTICE,"cannot install SIGINT handler: %s: %m");
	/* upon TERM log a timestamp and exit.  */
	if ((int)signal(SIGTERM,sigterm_handler) < 0)
		syslog(LOG_NOTICE,"cannot install SIGTERM handler: %s: %m");
	/* upon HUP redial and reconnect.  */
	if ((int)signal(SIGHUP,sighup_handler) < 0)
		syslog(LOG_NOTICE,"cannot install SIGHUP handler: %s: %m");
	/* Keep track of our original terminal values for redialing */
	if (tcgetattr(fd, &tty_orig) < 0) {           
		syslog(LOG_ERR, "tcgetattr: %m");
		exit_handler(1);
         }


	setup_line();

	if (redial_on_startup)
		sighup_handler();
	else
		attach_line();
	if (!(modem_control & CLOCAL)) {
		ioctl(fd, TIOCMGET, &comstate);
		if (!(comstate & TIOCM_CD)) { /* check for carrier */
			/* force a redial if no carrier */
			kill (getpid(), SIGHUP);
		}
	}
	for (;;) {
		sigset_t mask = 0;
		sigsuspend(&mask);
	}
}

void setup_line()
{
	tty.c_lflag = tty.c_iflag = tty.c_oflag = 0;
	tty.c_cflag = CREAD | CS8 | flow_control | modem_control;
	tty.c_ispeed = tty.c_ospeed = speed;
	/* set the line speed and flow control */
	if (tcsetattr(fd, TCSAFLUSH, &tty) < 0) {
                syslog(LOG_ERR, "tcsetattr(TCSAFLUSH): %m");
		exit_handler(1);
	}
	/* set data terminal ready */
	if (ioctl(fd, TIOCSDTR) < 0) {
                syslog(LOG_ERR, "ioctl(TIOCSDTR): %m");
                exit_handler(1);
        }
	/* Switch to slip line discipline. */
	if (ioctl(fd, TIOCSETD, &slipdisc) < 0) {
                syslog(LOG_ERR, "ioctl(TIOCSETD): %m");
		exit_handler(1);
	}
	/* Assert any compression or no-icmp flags. */
	if (ioctl(fd, SLIOCSFLAGS, &slflags) < 0) {
                syslog(LOG_ERR, "ioctl(SLIOCSFLAGS): %m");
		exit_handler(1);
	}
}

/* switch to slip line discipline and configure the network. */
void attach_line()
{
	int new_unit;

	/* find out what unit number we were assigned */
        if (ioctl(fd, SLIOCGUNIT, (caddr_t)&new_unit) < 0) {
                syslog(LOG_ERR, "ioctl(SLIOCGUNIT): %m");
                exit_handler(1);
        }
	/* don't compare unit numbers if this is the first time to attach. */
	if (unit < 0)
		unit = new_unit;
	/* iff the unit number changes either invoke config_cmd or punt. */
	if (config_cmd) {
		char *s;
		s = (char*) malloc(strlen(config_cmd) + 32);
		sprintf (s, "%s %d %d", config_cmd, unit, new_unit);
		syslog(LOG_NOTICE, "Configuring %s (sl%d):", dev, unit);
		syslog(LOG_NOTICE, "  '%s'", s);
		system(s);
		free (s);
		unit = new_unit;
	} else {
		if (new_unit != unit) {
			syslog(LOG_ERR, "slip unit changed from sl%d to sl%d, but no -u CMD was specified!");
			exit_handler(1);
		}
		syslog(LOG_NOTICE,"sl%d connected to %s at %d baud",unit,dev,speed);
	}
}

/* Signal handler for SIGHUP when carrier is dropped. */
void sighup_handler()
{
	if(exiting) return;
again:
	/* reset discipline */
	if (ioctl(fd, TIOCSETD, &ttydisc) < 0) {
		syslog(LOG_ERR, "ioctl(TIOCSETD): %m");
		exit_handler(1);
	}
	/* invoke a shell for redial_cmd or punt. */
	if (redial_cmd) {
		syslog(LOG_NOTICE,"SIGHUP on %s (sl%d); running %s",
		       dev,unit,redial_cmd);
		if (!(modem_control & CLOCAL)) {
			tty_orig.c_cflag |= CLOCAL;
			if (tcsetattr(fd, TCSAFLUSH, &tty_orig) < 0) {
				syslog(LOG_ERR, "tcsetattr(TCSAFLUSH): %m");
				exit_handler(1);
			}
		}
		system(redial_cmd);
		/* Now check again for carrier (dial command is done): */
		if (!(modem_control & CLOCAL)) {
			tty.c_cflag &= ~CLOCAL;
			if (tcsetattr(fd, TCSAFLUSH, &tty) < 0) {
				syslog(LOG_ERR, "tcsetattr(TCSAFLUSH): %m");
				exit_handler(1);
			}
			ioctl(fd, TIOCMGET, &comstate);
			if (!(comstate & TIOCM_CD)) { /* check for carrier */
				/* force a redial if no carrier */
				goto again;
			}
		}
	} else {
		/*
		 * No redial command.
		 *
		 * If modem control, just wait for carrier before
		 * falling through to setup_line() and attach_line().
		 * If no modem control, just fall through immediately.
		 */
		if (!(modem_control & CLOCAL)) {
		    int carrier = 0;

		    syslog(LOG_NOTICE, "Waiting for carrier on %s (sl%d)",
		      dev, unit);

		    /* Now wait for carrier before attaching line: */
		    while (! carrier) {
			/*
			 * Don't burn the CPU checking for carrier;
			 * carrier must be polled since there is no
			 * way to have a signal sent when carrier
			 * goes high (SIGHUP can only be sent when
			 * carrier is dropped); so add space between
			 * checks for carrier:
			 */
			sleep(2);

			/* Check for carrier present on tty port: */
			ioctl(fd, TIOCMGET, &comstate);
			if (comstate & TIOCM_CD) {
			    carrier = 1;
			}
		    }

		    syslog(LOG_NOTICE, "Carrier now present on %s (sl%d)",
		      dev, unit);
		}
	}
	setup_line();
	attach_line();
}
/* Signal handler for SIGINT.  We just log and exit. */
void sigint_handler()
{
	if(exiting) return;
	syslog(LOG_NOTICE,"sl%d on %s caught SIGINT, exiting.",unit,dev);
	exit_handler(0);
}
/* Signal handler for SIGTERM.  We just log and exit. */
void sigterm_handler()
{
	if(exiting) return;
	syslog(LOG_NOTICE,"SIGTERM on %s (sl%d); exiting",dev,unit);
	exit_handler(0);
}
/* Run config_cmd if specified before exiting. */
void exit_handler(int ret)
{
	if(exiting) return;
	exiting = 1;
	/*
	 * First close the slip line in case exit_cmd wants it (like to hang
	 * up a modem or something).
	 */
	if (fd != -1)
		close(fd);
	/* invoke a shell for exit_cmd. */
	if (exit_cmd) {
		syslog(LOG_NOTICE,"exiting after running %s", exit_cmd);
		system(exit_cmd);
	}
	exit(ret);
}

/* local variables: */
/* c-indent-level: 8 */
/* c-argdecl-indent: 0 */
/* c-label-offset: -8 */
/* c-continued-statement-offset: 8 */
/* c-brace-offset: 0 */
/* comment-column: 32 */
/* end: */