sys_term.c

经典的unix下telnetd代码

tty_setlitecho(int on)
{
# ifdef	ECHOCTL
    if (on)
	termbuf.c_lflag &= ~ECHOCTL;
    else
	termbuf.c_lflag |= ECHOCTL;
# endif
# ifdef	TCTLECH
    if (on)
	termbuf.c_lflag &= ~TCTLECH;
    else
	termbuf.c_lflag |= TCTLECH;
# endif
}

int
tty_iscrnl(void)
{
    return (termbuf.c_iflag & ICRNL);
}

/*
 * Try to guess whether speeds are "encoded" (4.2BSD) or just numeric (4.4BSD).
 */
#if B4800 != 4800
#define	DECODE_BAUD
#endif

#ifdef	DECODE_BAUD

/*
 * A table of available terminal speeds
 */
struct termspeeds {
    int	speed;
    int	value;
} termspeeds[] = {
    { 0,      B0 },      { 50,    B50 },    { 75,     B75 },
    { 110,    B110 },    { 134,   B134 },   { 150,    B150 },
    { 200,    B200 },    { 300,   B300 },   { 600,    B600 },
    { 1200,   B1200 },   { 1800,  B1800 },  { 2400,   B2400 },
    { 4800,   B4800 },
#ifdef	B7200
    { 7200,  B7200 },
#endif
    { 9600,   B9600 },
#ifdef	B14400
    { 14400,  B14400 },
#endif
#ifdef	B19200
    { 19200,  B19200 },
#endif
#ifdef	B28800
    { 28800,  B28800 },
#endif
#ifdef	B38400
    { 38400,  B38400 },
#endif
#ifdef	B57600
    { 57600,  B57600 },
#endif
#ifdef	B115200
    { 115200, B115200 },
#endif
#ifdef	B230400
    { 230400, B230400 },
#endif
    { -1,     0 }
};
#endif	/* DECODE_BUAD */

void
tty_tspeed(int val)
{
#ifdef	DECODE_BAUD
    struct termspeeds *tp;

    for (tp = termspeeds; (tp->speed != -1) && (val > tp->speed); tp++)
	;
    if (tp->speed == -1)	/* back up to last valid value */
	--tp;
    cfsetospeed(&termbuf, tp->value);
#else	/* DECODE_BUAD */
    cfsetospeed(&termbuf, val);
#endif	/* DECODE_BUAD */
}

void
tty_rspeed(int val)
{
#ifdef	DECODE_BAUD
    struct termspeeds *tp;

    for (tp = termspeeds; (tp->speed != -1) && (val > tp->speed); tp++)
	;
    if (tp->speed == -1)	/* back up to last valid value */
	--tp;
    cfsetispeed(&termbuf, tp->value);
#else	/* DECODE_BAUD */
    cfsetispeed(&termbuf, val);
#endif	/* DECODE_BAUD */
}

#ifdef PARENT_DOES_UTMP
extern	struct utmp wtmp;
extern char wtmpf[];

extern void utmp_sig_init (void);
extern void utmp_sig_reset (void);
extern void utmp_sig_wait (void);
extern void utmp_sig_notify (int);
# endif /* PARENT_DOES_UTMP */

#ifdef STREAMSPTY

/* I_FIND seems to live a life of its own */
static int my_find(int fd, char *module)
{
#if defined(I_FIND) && defined(I_LIST)
    static int flag;
    static struct str_list sl;
    int n;
    int i;
  
    if(!flag){
	n = ioctl(fd, I_LIST, 0);
	if(n < 0){
	    perror("ioctl(fd, I_LIST, 0)");
	    return -1;
	}
	sl.sl_modlist=(struct str_mlist*)malloc(n * sizeof(struct str_mlist));
	sl.sl_nmods = n;
	n = ioctl(fd, I_LIST, &sl);
	if(n < 0){
	    perror("ioctl(fd, I_LIST, n)");
	    return -1;
	}
	flag = 1;
    }
  
    for(i=0; i<sl.sl_nmods; i++)
	if(!strcmp(sl.sl_modlist[i].l_name, module))
	    return 1;
#endif
    return 0;
}

static void maybe_push_modules(int fd, char **modules)
{
    char **p;
    int err;

    for(p=modules; *p; p++){
	err = my_find(fd, *p);
	if(err == 1)
	    break;
	if(err < 0 && errno != EINVAL)
	    fatalperror(net, "my_find()");
	/* module not pushed or does not exist */
    }
    /* p points to null or to an already pushed module, now push all
       modules before this one */
  
    for(p--; p >= modules; p--){
	err = ioctl(fd, I_PUSH, *p);
	if(err < 0 && errno != EINVAL)
	    fatalperror(net, "I_PUSH");
    }
}
#endif

/*
 * getptyslave()
 *
 * Open the slave side of the pty, and do any initialization
 * that is necessary.  The return value is a file descriptor
 * for the slave side.
 */
void getptyslave(void)
{
    int t = -1;

    struct winsize ws;
    extern int def_row, def_col;
    extern int def_tspeed, def_rspeed;
    /*
     * Opening the slave side may cause initilization of the
     * kernel tty structure.  We need remember the state of
     * 	if linemode was turned on
     *	terminal window size
     *	terminal speed
     * so that we can re-set them if we need to.
     */

    if (slavefd != -1) {
	t = slavefd;
	goto gottty;
    }

    /*
     * Make sure that we don't have a controlling tty, and
     * that we are the session (process group) leader.
     */

#ifdef HAVE_SETSID
    if(setsid()<0)
	fatalperror(net, "setsid()");
#else
# ifdef	TIOCNOTTY
    t = open(_PATH_TTY, O_RDWR);
    if (t >= 0) {
	ioctl(t, TIOCNOTTY, (char *)0);
	close(t);
    }
# endif
#endif

# ifdef PARENT_DOES_UTMP
    /*
     * Wait for our parent to get the utmp stuff to get done.
     */
    utmp_sig_wait();
# endif

    t = cleanopen(line);
gottty:
    if (t < 0)
	fatalperror(net, line);

#ifdef  STREAMSPTY
    ttyfd = t;
	  

    /*
     * Not all systems have (or need) modules ttcompat and pckt so
     * don't flag it as a fatal error if they don't exist.
     */

    if (really_stream)
	{
	    /* these are the streams modules that we want pushed. note
	       that they are in reverse order, ptem will be pushed
	       first. maybe_push_modules() will try to push all modules
	       before the first one that isn't already pushed. i.e if
	       ldterm is pushed, only ttcompat will be attempted.

	       all this is because we don't know which modules are
	       available, and we don't know which modules are already
	       pushed (via autopush, for instance).

	       */
	     
	    char *ttymodules[] = { "ttcompat", "ldterm", "ptem", NULL };
	    char *ptymodules[] = { "pckt", NULL };

	    maybe_push_modules(t, ttymodules);
	    maybe_push_modules(ourpty, ptymodules);
	}
#endif
    /*
     * set up the tty modes as we like them to be.
     */
    init_termbuf();
# ifdef	TIOCSWINSZ
    if (def_row || def_col) {
	memset(&ws, 0, sizeof(ws));
	ws.ws_col = def_col;
	ws.ws_row = def_row;
	ioctl(t, TIOCSWINSZ, (char *)&ws);
    }
# endif

    /*
     * Settings for sgtty based systems
     */

    /*
     * Settings for UNICOS (and HPUX)
     */
# if defined(_CRAY) || defined(__hpux)
    termbuf.c_oflag = OPOST|ONLCR|TAB3;
    termbuf.c_iflag = IGNPAR|ISTRIP|ICRNL|IXON;
    termbuf.c_lflag = ISIG|ICANON|ECHO|ECHOE|ECHOK;
    termbuf.c_cflag = EXTB|HUPCL|CS8;
# endif

    /*
     * Settings for all other termios/termio based
     * systems, other than 4.4BSD.  In 4.4BSD the
     * kernel does the initial terminal setup.
     */
# if !(defined(_CRAY) || defined(__hpux)) && (BSD <= 43)
#  ifndef	OXTABS
#   define OXTABS	0
#  endif
    termbuf.c_lflag |= ECHO;
    termbuf.c_oflag |= ONLCR|OXTABS;
    termbuf.c_iflag |= ICRNL;
    termbuf.c_iflag &= ~IXOFF;
# endif
    tty_rspeed((def_rspeed > 0) ? def_rspeed : 9600);
    tty_tspeed((def_tspeed > 0) ? def_tspeed : 9600);

    /*
     * Set the tty modes, and make this our controlling tty.
     */
    set_termbuf();
    if (login_tty(t) == -1)
	fatalperror(net, "login_tty");
    if (net > 2)
	close(net);
    if (ourpty > 2) {
	close(ourpty);
	ourpty = -1;
    }
}

#ifndef	O_NOCTTY
#define	O_NOCTTY	0
#endif
/*
 * Open the specified slave side of the pty,
 * making sure that we have a clean tty.
 */

int cleanopen(char *line)
{
    int t;

#ifdef STREAMSPTY
    if (!really_stream)
#endif
	{
	    /*
	     * Make sure that other people can't open the
	     * slave side of the connection.
	     */
	    chown(line, 0, 0);
	    chmod(line, 0600);
	}

#ifdef HAVE_REVOKE
    revoke(line);
#endif

    t = open(line, O_RDWR|O_NOCTTY);

    if (t < 0)
	return(-1);

    /*
     * Hangup anybody else using this ttyp, then reopen it for
     * ourselves.
     */
# if !(defined(_CRAY) || defined(__hpux)) && (BSD <= 43) && !defined(STREAMSPTY)
    signal(SIGHUP, SIG_IGN);
#ifdef HAVE_VHANGUP
    vhangup();
#else
#endif
    signal(SIGHUP, SIG_DFL);
    t = open(line, O_RDWR|O_NOCTTY);
    if (t < 0)
	return(-1);
# endif
# if	defined(_CRAY) && defined(TCVHUP)
    {
	int i;
	signal(SIGHUP, SIG_IGN);
	ioctl(t, TCVHUP, (char *)0);
	signal(SIGHUP, SIG_DFL);

	i = open(line, O_RDWR);

	if (i < 0)
	    return(-1);
	close(t);
	t = i;
    }
# endif	/* defined(CRAY) && defined(TCVHUP) */
    return(t);
}

#if !defined(BSD4_4)

int login_tty(int t)
{
# if defined(TIOCSCTTY) && !defined(__hpux)
    if (ioctl(t, TIOCSCTTY, (char *)0) < 0)
	fatalperror(net, "ioctl(sctty)");
#  ifdef _CRAY
    /*
     * Close the hard fd to /dev/ttypXXX, and re-open through
     * the indirect /dev/tty interface.
     */
    close(t);
    if ((t = open("/dev/tty", O_RDWR)) < 0)
	fatalperror(net, "open(/dev/tty)");
#  endif
# else
    /*
     * We get our controlling tty assigned as a side-effect
     * of opening up a tty device.  But on BSD based systems,
     * this only happens if our process group is zero.  The
     * setsid() call above may have set our pgrp, so clear
     * it out before opening the tty...
     */
#ifdef HAVE_SETPGID
    setpgid(0, 0);
#else
    setpgrp(0, 0); /* if setpgid isn't available, setpgrp
		      probably takes arguments */
#endif
    close(open(line, O_RDWR));
# endif
    if (t != 0)
	dup2(t, 0);
    if (t != 1)
	dup2(t, 1);
    if (t != 2)
	dup2(t, 2);
    if (t > 2)
	close(t);
    return(0);
}
#endif	/* BSD <= 43 */

/*
 * This comes from ../../bsd/tty.c and should not really be here.
 */

/*
 * Clean the tty name.  Return a pointer to the cleaned version.
 */

static char *
clean_ttyname (char *tty)
{
  char *res = tty;

  if (strncmp (res, _PATH_DEV, sizeof(_PATH_DEV) - 1) == 0)
    res += sizeof(_PATH_DEV) - 1;
  if (strncmp (res, "pty/", 4) == 0)
    res += 4;
  if (strncmp (res, "ptym/", 5) == 0)
    res += 5;
  return res;
}

/*
 * Generate a name usable as an `ut_id', typically without `tty'.
 */

#ifdef HAVE_STRUCT_UTMP_UT_ID
static char *
make_id (char *tty)
{
  char *res = tty;
  
  if (strncmp (res, "pts/", 4) == 0)
    res += 4;
  if (strncmp (res, "tty", 3) == 0)
    res += 3;
  return res;
}
#endif

/*
 * startslave(host)
 *
 * Given a hostname, do whatever
 * is necessary to startup the login process on the slave side of the pty.
 */

/* ARGSUSED */
void
startslave(const char *host, const char *utmp_host,
	   int autologin, char *autoname)
{
    int i;

#ifdef AUTHENTICATION
    if (!autoname || !autoname[0])
	autologin = 0;

    if (autologin < auth_level) {
	fatal(net, "Authorization failed");
	exit(1);
    }
#endif

# ifdef	PARENT_DOES_UTMP
    utmp_sig_init();
# endif	/* PARENT_DOES_UTMP */

    if ((i = fork()) < 0)
	fatalperror(net, "fork");
    if (i) {
# ifdef PARENT_DOES_UTMP
	/*
	 * Cray parent will create utmp entry for child and send
	 * signal to child to tell when done.  Child waits for signal
	 * before doing anything important.
	 */
	int pid = i;
	void sigjob (int);

	setpgrp();
	utmp_sig_reset();		/* reset handler to default */
	/*
	 * Create utmp entry for child
	 */
	wtmp.ut_time = time(NULL);
	wtmp.ut_type = LOGIN_PROCESS;
	wtmp.ut_pid = pid;
	strncpy(wtmp.ut_user,  "LOGIN", sizeof(wtmp.ut_user));
	strncpy(wtmp.ut_host,  utmp_host, sizeof(wtmp.ut_host));
	strncpy(wtmp.ut_line,  clean_ttyname(line), sizeof(wtmp.ut_line));
#ifdef HAVE_STRUCT_UTMP_UT_ID
	strncpy(wtmp.ut_id, wtmp.ut_line + 3, sizeof(wtmp.ut_id));
#endif

	pututline(&wtmp);
	endutent();
	if ((i = open(wtmpf, O_WRONLY|O_APPEND)) >= 0) {
	    write(i, &wtmp, sizeof(struct utmp));
	    close(i);
	}
#ifdef	_CRAY
	signal(WJSIGNAL, sigjob);
#endif
	utmp_sig_notify(pid);
# endif	/* PARENT_DOES_UTMP */
    } else {
	getptyslave();
#if defined(DCE)
	/* if we authenticated via K5, try and join the PAG */
	kerberos5_dfspag();
#endif
	start_login(host, autologin, autoname);
	/*NOTREACHED*/
    }
}

char	*envinit[3];
extern char **environ;

void
init_env(void)
{
    char **envp;

    envp = envinit;
    if ((*envp = getenv("TZ")))
	*envp++ -= 3;
#if defined(_CRAY) || defined(__hpux)
    else
	*envp++ = "TZ=GMT0";
#endif
    *envp = 0;
    environ = envinit;
}

/* We won't agree with the Heimdal people about the right way to check for
 * bad environment variables, so we don't use this code.
 * See envvarok() in state.c instead.
 */
#if 0
/*
 * scrub_env()
 *
 * We only accept the environment variables listed below.
 */

static void
scrub_env(void)
{
    static const char *reject[] = {
	"TERMCAP=/",
	NULL
    };

    static const char *accept[] = {
	"XAUTH=", "XAUTHORITY=", "DISPLAY=",
	"TERM=",
	"EDITOR=",
	"PAGER=",
	"PRINTER=",
	"LOGNAME=",
	"POSIXLY_CORRECT=",
	"TERMCAP=",
	NULL
    };

    char **cpp, **cpp2;
    const char **p;
  
    for (cpp2 = cpp = environ; *cpp; cpp++) {
	int reject_it = 0;

	for(p = reject; *p; p++)
	    if(strncmp(*cpp, *p, strlen(*p)) == 0) {
		reject_it = 1;
		break;
	    }
	if (reject_it)
	    continue;

	for(p = accept; *p; p++)
	    if(strncmp(*cpp, *p, strlen(*p)) == 0)
		break;
	if(*p != NULL)
	    *cpp2++ = *cpp;
    }
    *cpp2 = NULL;
}
#endif

struct arg_val {
    int size;
    int argc;
    const char **argv;
};

static void addarg(struct arg_val*, const char*);

/*
 * start_login(host)
 *
 * Assuming that we are now running as a child processes, this
 * function will turn us into the login process.
 */

void
start_login(const char *host, int autologin, char *name)
{
    struct arg_val argv;