tty.c

自己精简过的PPPD代码。在嵌入中应用可以更好的发挥。比原先的小了很多

		}
		strlcpy(devnam, p, sizeof(devnam));
		if (stat(devnam, &devstat) < 0)
			fatal("Couldn't stat default device %s: %m", devnam);
	}


	/*
	 * Parse the tty options file.
	 * The per-tty options file should not change
	 * ptycommand, pty_socket, notty or devnam.
	 * options_for_tty doesn't override options set on the command line,
	 * except for some privileged options.
	 */
	/*/if (!options_for_tty())
		exit(EXIT_OPTION_ERROR);*/
}

/*
 * tty_check_options - do consistency checks on the options we were given.
 */
void
tty_check_options()
{
	struct stat statbuf;
	int fdflags;

	if (demand && notty) {
		option_error("demand-dialling is incompatible with notty");
		exit(EXIT_OPTION_ERROR);
	}
	if (demand && connect_script == 0 && ptycommand == NULL
	    && pty_socket == NULL) {
		option_error("connect script is required for demand-dialling\n");
		exit(EXIT_OPTION_ERROR);
	}
	/* default holdoff to 0 if no connect script has been given */
	if (connect_script == 0 && !holdoff_specified)
		holdoff = 0;

	if (using_pty) {
		if (!default_device) {
			option_error("%s option precludes specifying device name",
				     pty_socket? "socket": notty? "notty": "pty");
			exit(EXIT_OPTION_ERROR);
		}
		if (ptycommand != NULL && notty) {
			option_error("pty option is incompatible with notty option");
			exit(EXIT_OPTION_ERROR);
		}
		if (pty_socket != NULL && (ptycommand != NULL || notty)) {
			option_error("socket option is incompatible with pty and notty");
			exit(EXIT_OPTION_ERROR);
		}
		default_device = notty;
		lockflag = 0;
		modem = 0;
		if (notty && 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;
}

/*
 * connect_tty - get the serial port ready to start doing PPP.
 * That is, open the serial port, set its speed and mode, and run
 * the connector and/or welcomer.
 */
int connect_tty()
{
	char *connector;
	int fdflags;
#ifndef __linux__
	struct stat statbuf;
#endif
	char numbuf[16];

	/*
	 * Get a pty master/slave pair if the pty, notty, socket,
	 * or record options were specified.
	 */
	strlcpy(ppp_devnam, devnam, sizeof(ppp_devnam));
	pty_master = -1;
	pty_slave = -1;
	real_ttyfd = -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;
			return -1;
		}
		set_up_tty(pty_slave, 1);
	}

	/*
	 * Lock the device if we've been asked to.
	 */
	status = EXIT_LOCK_FAILED;
	if (lockflag && !privopen) {
		if (lock(devnam) < 0)
			goto errret;
		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;
	got_sigterm = 0;
	connector = doing_callback? callback_script: connect_script;
	if (devnam[0] != 0) {
		for (;;) {
			/* If the user specified the device name, become the
			   user before opening it. */
			int err, prio;

			prio = privopen? OPRIO_ROOT: tty_options[0].priority;
			if (prio < OPRIO_ROOT && seteuid(uid) == -1) {
				error("Unable to drop privileges before opening %s: %m\n",
				      devnam);
				status = EXIT_OPEN_FAILED;
				goto errret;
			}
			real_ttyfd = open(devnam, O_NONBLOCK | O_RDWR, 0);
			err = errno;
			if (prio < OPRIO_ROOT && seteuid(0) == -1)
				fatal("Unable to regain privileges");
			if (real_ttyfd >= 0)
				break;
			errno = err;
			if (err != EINTR) {
				error("Failed to open %s: %m", devnam);
				status = EXIT_OPEN_FAILED;
			}
			if (!persist || err != EINTR)
				goto errret;
		}
		ttyfd = real_ttyfd;
		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");

#ifndef __linux__
		/*
		 * Linux 2.4 and above blocks normal writes to the tty
		 * when it is in PPP line discipline, so this isn't needed.
		 */
		/*
		 * 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;
#endif /* __linux__ */

		/*
		 * 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));
	}

	/*
	 * 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");

			/* don't leak these to the ptycommand */
			(void) fcntl(ipipe[0], F_SETFD, FD_CLOEXEC);
			(void) fcntl(opipe[1], F_SETFD, FD_CLOEXEC);

			ok = device_script(ptycommand, opipe[0], ipipe[1], 1) == 0
				&& start_charshunt(ipipe[0], opipe[1]);
			close(ipipe[0]);
			close(ipipe[1]);
			close(opipe[0]);
			close(opipe[1]);
			if (!ok)
				goto errret;
		} else {
			if (device_script(ptycommand, pty_master, pty_master, 1) < 0)
				goto errret;
		}
	} else if (pty_socket != NULL) {
		int fd = open_socket(pty_socket);
		if (fd < 0)
			goto errret;
		if (!start_charshunt(fd, fd))
			goto errret;
		close(fd);
	} else if (notty) {
		if (!start_charshunt(0, 1))
			goto errret;
		dup2(fd_devnull, 0);
		dup2(fd_devnull, 1);
		if (log_to_fd == 1)
			log_to_fd = -1;
		if (log_to_fd != 2)
			dup2(fd_devnull, 2);
	} else if (record_file != NULL) {
		int fd = dup(ttyfd);
		if (!start_charshunt(fd, fd))
			goto errret;
	}

	if (using_pty || record_file != NULL) {
		ttyfd = pty_slave;
		close(pty_master);
		pty_master = -1;
	}

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

		if (initializer && initializer[0]) {
			if (device_script(initializer, ttyfd, ttyfd, 0) < 0) {
				error("Initializer script failed");
				status = EXIT_INIT_FAILED;
				goto errret;
			}
			if (got_sigterm) {
				disconnect_tty();
				goto errret;
			}
			info("Serial port initialized.");
		}

		if (connector && connector[0]) {
			if (device_script(connector, ttyfd, ttyfd, 0) < 0) {
				error("Connect script failed");
				status = EXIT_CONNECT_FAILED;
				goto errret;
			}
			if (got_sigterm) {
				disconnect_tty();
				goto errret;
			}
			info("Serial connection established.");
		}

		/* set line speed, flow control, etc.;
		   clear CLOCAL if modem option */
		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) {
		int i;
		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 || got_sigterm)
				goto errret;
		}
		close(i);
	}

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

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

	/*
	 * If we are initiating this connection, wait for a short
	 * time for something from the peer.  This can avoid bouncing
	 * our packets off his tty before he has it set up.
	 */
	if (connector != NULL || ptycommand != NULL || pty_socket != NULL)
		listen_time = connect_delay;

	return ttyfd;

 errret:
	if (pty_master >= 0) {
		close(pty_master);
		pty_master = -1;
	}
	ttyfd = -1;
	if (got_sigterm)
		asked_to_quit = 1;
	return -1;
}


void disconnect_tty()
{
	if (disconnect_script == NULL || hungup)
		return;
	if (real_ttyfd >= 0)
		set_up_tty(real_ttyfd, 1);
	if (device_script(disconnect_script, ttyfd, ttyfd, 0) < 0) {
		warn("disconnect script failed");
	} else {
		info("Serial link disconnected.");
	}
	stop_charshunt(NULL, 0);
}

void tty_close_fds()
{
	if (pty_slave >= 0)
		close(pty_slave);
	if (real_ttyfd >= 0) {
		close(real_ttyfd);
		real_ttyfd = -1;
	}
	/* N.B. ttyfd will == either pty_slave or real_ttyfd */
}

void cleanup_tty()
{
	if (real_ttyfd >= 0)
		finish_tty();
	tty_close_fds();
	if (locked) {
		unlock();
		locked = 0;
	}
}

/*
 * tty_do_send_config - set transmit-side PPP configuration.
 * We set the extended transmit ACCM here as well.
 */
void
tty_do_send_config(mtu, accm, pcomp, accomp)
    int mtu;
    u_int32_t accm;
    int pcomp, accomp;
{
	tty_set_xaccm(xmit_accm);
	tty_send_config(mtu, accm, pcomp, accomp);
}

/*
 * finish_tty - restore the terminal device to its original settings
 */
static void
finish_tty()
{
	/* drop dtr to hang up */
	if (!default_device && modem) {
		setdtr(real_ttyfd, 0);
		/*
		 * This sleep is in case the serial port has CLOCAL set by default,
		 * and consequently will reassert DTR when we close the device.
		 */
		sleep(1);
	}

	restore_tty(real_ttyfd);

#ifndef __linux__
	if (tty_mode != (mode_t) -1) {
		if (fchmod(real_ttyfd, tty_mode) != 0)
			error("Couldn't restore tty permissions");