tty.c

经典的ppp程序

		if (!start_charshunt(fd, fd))
			return -1;
	} else if (notty) {
		if (!start_charshunt(0, 1))
			return -1;
	} else if (record_file != NULL) {
		if (!start_charshunt(ttyfd, ttyfd))
			return -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;
				return -1;
			}
			if (kill_link) {
				disconnect_tty();
				return -1;
			}
			info("Serial port initialized.");
		}
		error("connector=%s",connector);
		if (connector && connector[0]) {
			if (device_script(connector, ttyfd, ttyfd, 0) < 0) {
				error("Connect script failed");
				status = EXIT_CONNECT_FAILED;
				return -1;
			}
			if (kill_link) {
				disconnect_tty();
				return -1;
			}
			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 || kill_link)
				return -1;
		}
		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)
		listen_time = connect_delay;

	return ttyfd;
}


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.");
	}
}

void tty_close_fds()
{
	if (pty_master >= 0)
		close(pty_master);
	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);

	if (tty_mode != (mode_t) -1) {
		if (fchmod(real_ttyfd, tty_mode) != 0) {
			/* XXX if devnam is a symlink, this will change the link */
			chmod(devnam, tty_mode);
		}
	}

	close(real_ttyfd);
	real_ttyfd = -1;
}

/*
 * maybe_relock - our PID has changed, maybe update the lock file.
 */
static void
maybe_relock(arg, pid)
    void *arg;
    int pid;
{
    if (locked)
	relock(pid);
}

/*
 * open_socket - establish a stream socket connection to the nominated
 * host and port.
 */
static int
open_socket(dest)
    char *dest;
{
    char *sep, *endp = NULL;
    int sock, port = -1;
    u_int32_t host;
    struct hostent *hent;
    struct sockaddr_in sad;

    /* parse host:port and resolve host to an IP address */
    sep = strchr(dest, ':');
    if (sep != NULL)
	port = strtol(sep+1, &endp, 10);
    if (port < 0 || endp == sep+1 || sep == dest) {
	error("Can't parse host:port for socket destination");
	return -1;
    }
    *sep = 0;
    host = inet_addr(dest);
    if (host == (u_int32_t) -1) {
	hent = gethostbyname(dest);
	if (hent == NULL) {
	    error("%s: unknown host in socket option", dest);
	    *sep = ':';
	    return -1;
	}
	host = *(u_int32_t *)(hent->h_addr_list[0]);
    }
    *sep = ':';

    /* get a socket and connect it to the other end */
    sock = socket(PF_INET, SOCK_STREAM, 0);
    if (sock < 0) {
	error("Can't create socket: %m");
	return -1;
    }
    memset(&sad, 0, sizeof(sad));
    sad.sin_family = AF_INET;
    sad.sin_port = htons(port);
    sad.sin_addr.s_addr = host;
    if (connect(sock, (struct sockaddr *)&sad, sizeof(sad)) < 0) {
	error("Can't connect to %s: %m", dest);
	close(sock);
	return -1;
    }

    return sock;
}


/*
 * start_charshunt - create a child process to run the character shunt.
 */
static int
start_charshunt(ifd, ofd)
    int ifd, ofd;
{
    int cpid;

    cpid = fork();
    if (cpid == -1) {
	error("Can't fork process for character shunt: %m");
	return 0;
    }
    if (cpid == 0) {
	/* child */
	close(pty_slave);
	setuid(uid);
	if (getuid() != uid)
	    fatal("setuid failed");
	setgid(getgid());
	if (!nodetach)
	    log_to_fd = -1;
	charshunt(ifd, ofd, record_file);
	exit(0);
    }
    charshunt_pid = cpid;
    add_notifier(&sigreceived, stop_charshunt, 0);
    close(pty_master);
    pty_master = -1;
    ttyfd = pty_slave;
    record_child(cpid, "pppd (charshunt)", charshunt_done, NULL);
    return 1;
}

static void
charshunt_done(arg)
    void *arg;
{
	charshunt_pid = 0;
}

static void
stop_charshunt(arg, sig)
    void *arg;
    int sig;
{
	if (charshunt_pid)
		kill(charshunt_pid, (sig == SIGINT? sig: SIGTERM));
}

/*
 * charshunt - the character shunt, which passes characters between
 * the pty master side and the serial port (or stdin/stdout).
 * This runs as the user (not as root).
 * (We assume ofd >= ifd which is true the way this gets called. :-).
 */
static void
charshunt(ifd, ofd, record_file)
    int ifd, ofd;
    char *record_file;
{
    int n, nfds;
    fd_set ready, writey;
    u_char *ibufp, *obufp;
    int nibuf, nobuf;
    int flags;
    int pty_readable, stdin_readable;
    struct timeval lasttime;
    FILE *recordf = NULL;
    int ilevel, olevel, max_level;
    struct timeval levelt, tout, *top;
    extern u_char inpacket_buf[];

    /*
     * Reset signal handlers.
     */
    signal(SIGHUP, SIG_IGN);		/* Hangup */
    signal(SIGINT, SIG_DFL);		/* Interrupt */
    signal(SIGTERM, SIG_DFL);		/* Terminate */
    signal(SIGCHLD, SIG_DFL);
    signal(SIGUSR1, SIG_DFL);
    signal(SIGUSR2, SIG_DFL);
    signal(SIGABRT, SIG_DFL);
    signal(SIGALRM, SIG_DFL);
    signal(SIGFPE, SIG_DFL);
    signal(SIGILL, SIG_DFL);
    signal(SIGPIPE, SIG_DFL);
    signal(SIGQUIT, SIG_DFL);
    signal(SIGSEGV, SIG_DFL);
#ifdef SIGBUS
    signal(SIGBUS, SIG_DFL);
#endif
#ifdef SIGEMT
    signal(SIGEMT, SIG_DFL);
#endif
#ifdef SIGPOLL
    signal(SIGPOLL, SIG_DFL);
#endif
#ifdef SIGPROF
    signal(SIGPROF, SIG_DFL);
#endif
#ifdef SIGSYS
    signal(SIGSYS, SIG_DFL);
#endif
#ifdef SIGTRAP
    signal(SIGTRAP, SIG_DFL);
#endif
#ifdef SIGVTALRM
    signal(SIGVTALRM, SIG_DFL);
#endif
#ifdef SIGXCPU
    signal(SIGXCPU, SIG_DFL);
#endif
#ifdef SIGXFSZ
    signal(SIGXFSZ, SIG_DFL);
#endif

    /*
     * Open the record file if required.
     */
    if (record_file != NULL) {
	recordf = fopen(record_file, "a");
	if (recordf == NULL)
	    error("Couldn't create record file %s: %m", record_file);
    }

    /* set all the fds to non-blocking mode */
    flags = fcntl(pty_master, F_GETFL);
    if (flags == -1
	|| fcntl(pty_master, F_SETFL, flags | O_NONBLOCK) == -1)
	warn("couldn't set pty master to nonblock: %m");
    flags = fcntl(ifd, F_GETFL);
    if (flags == -1
	|| fcntl(ifd, F_SETFL, flags | O_NONBLOCK) == -1)
	warn("couldn't set %s to nonblock: %m", (ifd==0? "stdin": "tty"));
    if (ofd != ifd) {
	flags = fcntl(ofd, F_GETFL);
	if (flags == -1
	    || fcntl(ofd, F_SETFL, flags | O_NONBLOCK) == -1)
	    warn("couldn't set stdout to nonblock: %m");
    }

    nibuf = nobuf = 0;
    ibufp = obufp = NULL;
    pty_readable = stdin_readable = 1;

    ilevel = olevel = 0;
    gettimeofday(&levelt, NULL);
    if (max_data_rate) {
	max_level = max_data_rate / 10;
	if (max_level < 100)
	    max_level = 100;
    } else
	max_level = PPP_MRU + PPP_HDRLEN + 1;

    nfds = (ofd > pty_master? ofd: pty_master) + 1;
    if (recordf != NULL) {
	gettimeofday(&lasttime, NULL);
	putc(7, recordf);	/* put start marker */
	putc(lasttime.tv_sec >> 24, recordf);
	putc(lasttime.tv_sec >> 16, recordf);
	putc(lasttime.tv_sec >> 8, recordf);
	putc(lasttime.tv_sec, recordf);
	lasttime.tv_usec = 0;
    }

    while (nibuf != 0 || nobuf != 0 || pty_readable || stdin_readable) {
	top = 0;
	tout.tv_sec = 0;
	tout.tv_usec = 10000;
	FD_ZERO(&ready);
	FD_ZERO(&writey);
	if (nibuf != 0) {
	    if (ilevel >= max_level)
		top = &tout;
	    else
		FD_SET(pty_master, &writey);
	} else if (stdin_readable)
	    FD_SET(ifd, &ready);
	if (nobuf != 0) {
	    if (olevel >= max_level)
		top = &tout;
	    else
		FD_SET(ofd, &writey);
	} else if (pty_readable)
	    FD_SET(pty_master, &ready);
	if (select(nfds, &ready, &writey, NULL, top) < 0) {
	    if (errno != EINTR)
		fatal("select");
	    continue;
	}
	if (max_data_rate) {
	    double dt;
	    int nbt;
	    struct timeval now;

	    gettimeofday(&now, NULL);
	    dt = (now.tv_sec - levelt.tv_sec
		  + (now.tv_usec - levelt.tv_usec) / 1e6);
	    nbt = (int)(dt * max_data_rate);
	    ilevel = (nbt < 0 || nbt > ilevel)? 0: ilevel - nbt;
	    olevel = (nbt < 0 || nbt > olevel)? 0: olevel - nbt;
	    levelt = now;
	} else
	    ilevel = olevel = 0;
	if (FD_ISSET(ifd, &ready)) {
	    ibufp = inpacket_buf;
	    nibuf = read(ifd, ibufp, PPP_MRU + PPP_HDRLEN);
	    if (nibuf < 0 && errno == EIO)
		nibuf = 0;
	    if (nibuf < 0) {
		if (!(errno == EINTR || errno == EAGAIN)) {
		    error("Error reading standard input: %m");
		    break;
		}
		nibuf = 0;
	    } else if (nibuf == 0) {
		/* end of file from stdin */
		stdin_readable = 0;
		/* do a 0-length write, hopefully this will generate
		   an EOF (hangup) on the slave side. */
		write(pty_master, inpacket_buf, 0);
		if (recordf)
		    if (!record_write(recordf, 4, NULL, 0, &lasttime))
			recordf = NULL;
	    } else {
		FD_SET(pty_master, &writey);
		if (recordf)
		    if (!record_write(recordf, 2, ibufp, nibuf, &lasttime))
			recordf = NULL;
	    }
	}
	if (FD_ISSET(pty_master, &ready)) {
	    obufp = outpacket_buf;
	    nobuf = read(pty_master, obufp, PPP_MRU + PPP_HDRLEN);
	    if (nobuf < 0 && errno == EIO)
		nobuf = 0;
	    if (nobuf < 0) {
		if (!(errno == EINTR || errno == EAGAIN)) {
		    error("Error reading pseudo-tty master: %m");
		    break;
		}
		nobuf = 0;
	    } else if (nobuf == 0) {
		/* end of file from the pty - slave side has closed */
		pty_readable = 0;
		stdin_readable = 0;	/* pty is not writable now */
		nibuf = 0;
		close(ofd);
		if (recordf)
		    if (!record_write(recordf, 3, NULL, 0, &lasttime))
			recordf = NULL;
	    } else {
		FD_SET(ofd, &writey);
		if (recordf)
		    if (!record_write(recordf, 1, obufp, nobuf, &lasttime))
			recordf = NULL;
	    }
	}
	if (FD_ISSET(ofd, &writey)) {
	    n = nobuf;
	    if (olevel + n > max_level)
		n = max_level - olevel;
	    n = write(ofd, obufp, n);
	    if (n < 0) {
		if (errno == EIO) {
		    pty_readable = 0;
		    nobuf = 0;
		} else if (errno != EAGAIN && errno != EINTR) {
		    error("Error writing standard output: %m");
		    break;
		}
	    } else {
		obufp += n;
		nobuf -= n;
		olevel += n;
	    }
	}
	if (FD_ISSET(pty_master, &writey)) {
	    n = nibuf;
	    if (ilevel + n > max_level)
		n = max_level - ilevel;
	    n = write(pty_master, ibufp, n);
	    if (n < 0) {
		if (errno == EIO) {
		    stdin_readable = 0;
		    nibuf = 0;
		} else if (errno != EAGAIN && errno != EINTR) {
		    error("Error writing pseudo-tty master: %m");
		    break;
		}
	    } else {
		ibufp += n;
		nibuf -= n;
		ilevel += n;
	    }
	}
    }
    exit(0);
}

static int
record_write(f, code, buf, nb, tp)
    FILE *f;
    int code;
    u_char *buf;
    int nb;
    struct timeval *tp;
{
    struct timeval now;
    int diff;

    gettimeofday(&now, NULL);
    now.tv_usec /= 100000;	/* actually 1/10 s, not usec now */
    diff = (now.tv_sec - tp->tv_sec) * 10 + (now.tv_usec - tp->tv_usec);
    if (diff > 0) {
	if (diff > 255) {
	    putc(5, f);
	    putc(diff >> 24, f);
	    putc(diff >> 16, f);
	    putc(diff >> 8, f);
	    putc(diff, f);
	} else {
	    putc(6, f);
	    putc(diff, f);
	}
	*tp = now;
    }
    putc(code, f);
    if (buf != NULL) {
	putc(nb >> 8, f);
	putc(nb, f);
	fwrite(buf, nb, 1, f);
    }
    fflush(f);
    if (ferror(f)) {
	error("Error writing record file: %m");
	return 0;
    }
    return 1;
}