sys_term.c

经典的unix下telnetd代码

    char *user;
    int save_errno;
    char *buf;
    extern char *gettytab[2], *gettyent;

#ifdef HAVE_UTMPX_H
    int pid = getpid();
    struct utmpx utmpx;
    char *clean_tty;

    /*
     * Create utmp entry for child
     */

    clean_tty = clean_ttyname(line);
    memset(&utmpx, 0, sizeof(utmpx));
    strncpy(utmpx.ut_user,  ".telnet", sizeof(utmpx.ut_user));
    strncpy(utmpx.ut_line,  clean_tty, sizeof(utmpx.ut_line));
#ifdef HAVE_STRUCT_UTMP_UT_ID
    strncpy(utmpx.ut_id, make_id(clean_tty), sizeof(utmpx.ut_id));
#endif
    utmpx.ut_pid = pid;
	
    utmpx.ut_type = LOGIN_PROCESS;

    gettimeofday (&utmpx.ut_tv, NULL);
    if (pututxline(&utmpx) == NULL)
	fatal(net, "pututxline failed");
#endif

#if 0
    scrub_env();
#endif
    /*
     * -h : pass on name of host.
     *		WARNING:  -h is accepted by login if and only if
     *			getuid() == 0.
     * -p : don't clobber the environment (so terminal type stays set).
     *
     * -f : force this login, he has already been authenticated
     */

    /* init argv structure */ 
    argv.size=0;
    argv.argc=0;
    argv.argv=malloc(0); /*so we can call realloc later */
    addarg(&argv, "login");
    addarg(&argv, "-h");
    addarg(&argv, host);
    addarg(&argv, "-p");
    if(name[0])
	user = name;
    else
	user = getenv("USER");
#ifdef AUTHENTICATION
    if (auth_level < 0 || autologin != AUTH_VALID) {
	if(!no_warn) {
	    printf("User not authenticated. "
		"Using plaintext username and password\r\n");
	}
	if(log_unauth) 
	    syslog(LOG_INFO, "unauthenticated access from %s (%s)", 
		   host, user ? user : "unknown user");
    }
    if (auth_level >= 0 && autologin == AUTH_VALID)
	addarg(&argv, "-f");
#endif
    if(user){
	addarg(&argv, "--");
	addarg(&argv, strdup(user));
    }
    if (new_login == NULL && cgetent(&buf, gettytab, gettyent) >= 0) {
	cgetstr(buf, "lo", &new_login);
	cgetclose();
    }
    if (new_login == NULL)
	new_login = _PATH_LOGIN;

    if (getenv("USER")) {
	/*
	 * Assume that login will set the USER variable
	 * correctly.  For SysV systems, this means that
	 * USER will no longer be set, just LOGNAME by
	 * login.  (The problem is that if the auto-login
	 * fails, and the user then specifies a different
	 * account name, he can get logged in with both
	 * LOGNAME and USER in his environment, but the
	 * USER value will be wrong.
	 */
	unsetenv("USER");
    }
    closelog();
    /*
     * This sleep(1) is in here so that telnetd can
     * finish up with the tty.  There's a race condition
     * the login banner message gets lost...
     */
    sleep(1);

    execv(new_login, (char *const*)argv.argv);
    save_errno = errno;
    syslog(LOG_ERR, "%s: %m", new_login);
    fatalperror_errno(net, new_login, save_errno);
    /*NOTREACHED*/
}

static void
addarg(struct arg_val *argv, const char *val)
{
    const char **tmp;

    if (argv->size <= argv->argc+1) {
	tmp = realloc(argv->argv, sizeof(char*) * (argv->size + 10));
	if (tmp == NULL) {
	    if (argv->argv)
		    free(argv->argv);
	    argv->argv = NULL;
	    argv->size = 0;
	    fatal (net, "realloc: out of memory");
	}
	argv->argv = tmp;
	argv->size+=10;
    }
    argv->argv[argv->argc++] = val;
    argv->argv[argv->argc]   = NULL;
}


/*
 * rmut()
 *
 * This is the function called by cleanup() to
 * remove the utmp entry for this person.
 */

#ifdef HAVE_UTMPX_H
static void
rmut(void)
{
    struct utmpx utmpx, *non_save_utxp;
    char *clean_tty = clean_ttyname(line);

    /*
     * This updates the utmpx and utmp entries and make a wtmp/x entry
     */

    setutxent();
    memset(&utmpx, 0, sizeof(utmpx));
    strncpy(utmpx.ut_line, clean_tty, sizeof(utmpx.ut_line));
    utmpx.ut_type = LOGIN_PROCESS;
    non_save_utxp = getutxline(&utmpx);
    if (non_save_utxp) {
	struct utmpx *utxp;
	char user0;

	utxp = malloc(sizeof(struct utmpx));
	*utxp = *non_save_utxp;
	user0 = utxp->ut_user[0];
	utxp->ut_user[0] = '\0';
	utxp->ut_type = DEAD_PROCESS;
#ifdef HAVE_STRUCT_UTMPX_UT_EXIT
#ifdef _STRUCT___EXIT_STATUS
	utxp->ut_exit.__e_termination = 0;
	utxp->ut_exit.__e_exit = 0;
#elif defined(__osf__) /* XXX */
	utxp->ut_exit.ut_termination = 0;
	utxp->ut_exit.ut_exit = 0;
#else	
	utxp->ut_exit.e_termination = 0;
	utxp->ut_exit.e_exit = 0;
#endif
#endif
	gettimeofday(&utxp->ut_tv, NULL);
	pututxline(utxp);
#ifdef WTMPX_FILE
	utxp->ut_user[0] = user0;
	updwtmpx(WTMPX_FILE, utxp);
#elif defined(WTMP_FILE)
	/* This is a strange system with a utmpx and a wtmp! */
	{
	  int f = open(wtmpf, O_WRONLY|O_APPEND);
	  struct utmp wtmp;
	  if (f >= 0) {
	    strncpy(wtmp.ut_line,  clean_tty, sizeof(wtmp.ut_line));
	    strncpy(wtmp.ut_name,  "", sizeof(wtmp.ut_name));
#ifdef HAVE_STRUCT_UTMP_UT_HOST
	    strncpy(wtmp.ut_host,  "", sizeof(wtmp.ut_host));
#endif
	    wtmp.ut_time = time(NULL);
	    write(f, &wtmp, sizeof(wtmp));
	    close(f);
	  }
	}
#endif
	free (utxp);
    }
    endutxent();
}  /* end of rmut */
#endif

#if !defined(HAVE_UTMPX_H) && !(defined(_CRAY) || defined(__hpux))
static void
rmut(void)
{
    int f;
    int found = 0;
    struct utmp *u, *utmp;
    int nutmp;
    struct stat statbf;
    char *clean_tty = clean_ttyname(line);

    f = open(utmpf, O_RDWR);
    if (f >= 0) {
	fstat(f, &statbf);
	utmp = (struct utmp *)malloc((unsigned)statbf.st_size);
	if (!utmp)
	    syslog(LOG_ERR, "utmp malloc failed");
	if (statbf.st_size && utmp) {
	    nutmp = read(f, utmp, (int)statbf.st_size);
	    nutmp /= sizeof(struct utmp);

	    for (u = utmp ; u < &utmp[nutmp] ; u++) {
		if (strncmp(u->ut_line,
			    clean_tty,
			    sizeof(u->ut_line)) ||
		    u->ut_name[0]==0)
		    continue;
		lseek(f, ((long)u)-((long)utmp), L_SET);
		strncpy(u->ut_name,  "", sizeof(u->ut_name));
#ifdef HAVE_STRUCT_UTMP_UT_HOST
		strncpy(u->ut_host,  "", sizeof(u->ut_host));
#endif
		u->ut_time = time(NULL);
		write(f, u, sizeof(wtmp));
		found++;
	    }
	}
	close(f);
    }
    if (found) {
	f = open(wtmpf, O_WRONLY|O_APPEND);
	if (f >= 0) {
	    strncpy(wtmp.ut_line,  clean_tty, sizeof(wtmp.ut_line));
	    strncpy(wtmp.ut_name,  "", sizeof(wtmp.ut_name));
#ifdef HAVE_STRUCT_UTMP_UT_HOST
	    strncpy(wtmp.ut_host,  "", sizeof(wtmp.ut_host));
#endif
	    wtmp.ut_time = time(NULL);
	    write(f, &wtmp, sizeof(wtmp));
	    close(f);
	}
    }
    chmod(line, 0666);
    chown(line, 0, 0);
    line[strlen("/dev/")] = 'p';
    chmod(line, 0666);
    chown(line, 0, 0);
}  /* end of rmut */
#endif	/* CRAY */

#if defined(__hpux) && !defined(HAVE_UTMPX_H)
static void
rmut (char *line)
{
    struct utmp utmp;
    struct utmp *utptr;
    int fd;			/* for /etc/wtmp */

    utmp.ut_type = USER_PROCESS;
    strncpy(utmp.ut_line, clean_ttyname(line), sizeof(utmp.ut_line));
    setutent();
    utptr = getutline(&utmp);
    /* write it out only if it exists */
    if (utptr) {
	utptr->ut_type = DEAD_PROCESS;
	utptr->ut_time = time(NULL);
	pututline(utptr);
	/* set wtmp entry if wtmp file exists */
	if ((fd = open(wtmpf, O_WRONLY | O_APPEND)) >= 0) {
	    write(fd, utptr, sizeof(utmp));
	    close(fd);
	}
    }
    endutent();

    chmod(line, 0666);
    chown(line, 0, 0);
    line[14] = line[13];
    line[13] = line[12];
    line[8] = 'm';
    line[9] = '/';
    line[10] = 'p';
    line[11] = 't';
    line[12] = 'y';
    chmod(line, 0666);
    chown(line, 0, 0);
}
#endif

/*
 * cleanup()
 *
 * This is the routine to call when we are all through, to
 * clean up anything that needs to be cleaned up.
 */

#ifdef PARENT_DOES_UTMP

void
cleanup(int sig)
{
#ifdef _CRAY
    static int incleanup = 0;
    int t;
    int child_status; /* status of child process as returned by waitpid */
    int flags = WNOHANG|WUNTRACED;
    
    /*
     * 1: Pick up the zombie, if we are being called
     *    as the signal handler.
     * 2: If we are a nested cleanup(), return.
     * 3: Try to clean up TMPDIR.
     * 4: Fill in utmp with shutdown of process.
     * 5: Close down the network and pty connections.
     * 6: Finish up the TMPDIR cleanup, if needed.
     */
    if (sig == SIGCHLD) {
	while (waitpid(-1, &child_status, flags) > 0)
	    ;	/* VOID */
	/* Check if the child process was stopped
	 * rather than exited.  We want cleanup only if
	 * the child has died.
	 */
	if (WIFSTOPPED(child_status)) {
	    return;
	}
    }
    t = sigblock(sigmask(SIGCHLD));
    if (incleanup) {
	sigsetmask(t);
	return;
    }
    incleanup = 1;
    sigsetmask(t);
    
    t = cleantmp(&wtmp);
    setutent();	/* just to make sure */
#endif /* CRAY */
    rmut(line);
    close(ourpty);
    shutdown(net, 2);
#ifdef _CRAY
    if (t == 0)
	cleantmp(&wtmp);
#endif /* CRAY */
    exit(1);
}

#else /* PARENT_DOES_UTMP */

void
cleanup(int sig)
{
#if defined(HAVE_UTMPX_H) || !defined(HAVE_LOGWTMP)
    rmut();
#ifdef HAVE_VHANGUP
#ifndef __sgi
    vhangup(); /* XXX */
#endif
#endif
#else
    char *p;
    
    p = line + sizeof("/dev/") - 1;
    if (logout(p))
	logwtmp(p, "", "");
    chmod(line, 0666);
    chown(line, 0, 0);
    *p = 'p';
    chmod(line, 0666);
    chown(line, 0, 0);
#endif
    shutdown(net, 2);
    _exit(1);
}

#endif /* PARENT_DOES_UTMP */

#ifdef PARENT_DOES_UTMP
/*
 * _utmp_sig_rcv
 * utmp_sig_init
 * utmp_sig_wait
 *	These three functions are used to coordinate the handling of
 *	the utmp file between the server and the soon-to-be-login shell.
 *	The server actually creates the utmp structure, the child calls
 *	utmp_sig_wait(), until the server calls utmp_sig_notify() and
 *	signals the future-login shell to proceed.
 */
static int caught=0;		/* NZ when signal intercepted */
static void (*func)();		/* address of previous handler */

void
_utmp_sig_rcv(sig)
     int sig;
{
    caught = 1;
    signal(SIGUSR1, func);
}

void
utmp_sig_init()
{
    /*
     * register signal handler for UTMP creation
     */
    if ((int)(func = signal(SIGUSR1, _utmp_sig_rcv)) == -1)
	fatalperror(net, "telnetd/signal");
}

void
utmp_sig_reset()
{
    signal(SIGUSR1, func);	/* reset handler to default */
}

# ifdef __hpux
# define sigoff() /* do nothing */
# define sigon() /* do nothing */
# endif

void
utmp_sig_wait()
{
    /*
     * Wait for parent to write our utmp entry.
	 */
    sigoff();
    while (caught == 0) {
	pause();	/* wait until we get a signal (sigon) */
	sigoff();	/* turn off signals while we check caught */
    }
    sigon();		/* turn on signals again */
}

void
utmp_sig_notify(pid)
{
    kill(pid, SIGUSR1);
}

#ifdef _CRAY
static int gotsigjob = 0;

	/*ARGSUSED*/
void
sigjob(sig)
     int sig;
{
    int jid;
    struct jobtemp *jp;

    while ((jid = waitjob(NULL)) != -1) {
	if (jid == 0) {
	    return;
	}
	gotsigjob++;
	jobend(jid, NULL, NULL);
    }
}

/*
 *	jid_getutid:
 *		called by jobend() before calling cleantmp()
 *		to find the correct $TMPDIR to cleanup.
 */

struct utmp *
jid_getutid(jid)
     int jid;
{
    struct utmp *cur = NULL;

    setutent();	/* just to make sure */
    while (cur = getutent()) {
	if ( (cur->ut_type != NULL) && (jid == cur->ut_jid) ) {
	    return(cur);
	}
    }

    return(0);
}

/*
 * Clean up the TMPDIR that login created.
 * The first time this is called we pick up the info
 * from the utmp.  If the job has already gone away,
 * then we'll clean up and be done.  If not, then
 * when this is called the second time it will wait
 * for the signal that the job is done.
 */
int
cleantmp(wtp)
     struct utmp *wtp;
{
    struct utmp *utp;
    static int first = 1;
    int mask, omask, ret;
    extern struct utmp *getutid (const struct utmp *_Id);


    mask = sigmask(WJSIGNAL);

    if (first == 0) {
	omask = sigblock(mask);
	while (gotsigjob == 0)
	    sigpause(omask);
	return(1);
    }
    first = 0;
    setutent();	/* just to make sure */

    utp = getutid(wtp);
    if (utp == 0) {
	syslog(LOG_ERR, "Can't get /etc/utmp entry to clean TMPDIR");
	return(-1);
    }
    /*
     * Nothing to clean up if the user shell was never started.
     */
    if (utp->ut_type != USER_PROCESS || utp->ut_jid == 0)
	return(1);

    /*
     * Block the WJSIGNAL while we are in jobend().
     */
    omask = sigblock(mask);
    ret = jobend(utp->ut_jid, utp->ut_tpath, utp->ut_user);
    sigsetmask(omask);
    return(ret);
}

/*
 *	jobend
 *		Assumes that if path is not NULL, then user is also
 * 		not NULL.
 */
int
jobend(jid, path, user)
     int jid;
     char *path;
     char *user;
{
    static int saved_jid = 0;
    static int pty_saved_jid = 0;
    static char saved_path[sizeof(wtmp.ut_tpath)+1];
    static char saved_user[sizeof(wtmp.ut_user)+1];

    /*
     * this little piece of code comes into play
     * only when ptyreconnect is used to reconnect
     * to an previous session.
     *
     * this is the only time when the
     * "saved_jid != jid" code is executed.
     */

    if ( saved_jid && saved_jid != jid ) {
	if (!path) {	/* called from signal handler */
	    pty_saved_jid = jid;
	} else {
	    pty_saved_jid = saved_jid;
	}
    }

    if (path) {
	strncpy(saved_path, path, sizeof(saved_path) - 1);
	strncpy(saved_user, path, sizeof(saved_user) - 1);
	saved_path[sizeof(saved_path) - 1] = '\0';
	saved_user[sizeof(saved_user) - 1] = '\0';
    }
    if (saved_jid == 0) {
	saved_jid = jid;
	return(0);
    }

    /* if the jid has changed, get the correct entry from the utmp file */

    if ( saved_jid != jid ) {
	struct utmp *utp = NULL;
	struct utmp *jid_getutid();

	utp = jid_getutid(pty_saved_jid);

	if (utp == 0) {
	    syslog(LOG_ERR, "Can't get /etc/utmp entry to clean TMPDIR");
	    return(-1);
	}

	cleantmpdir(jid, utp->ut_tpath, utp->ut_user);
	return(1);
    }

    cleantmpdir(jid, saved_path, saved_user);
    return(1);
}

/*
 * Fork a child process to clean up the TMPDIR
 */
cleantmpdir(jid, tpath, user)
     int jid;
     char *tpath;
     char *user;
{
    switch(fork()) {
    case -1:
	syslog(LOG_ERR, "TMPDIR cleanup(%s): fork() failed: %m",
	       tpath);
	break;
    case 0:
	execl(CLEANTMPCMD, CLEANTMPCMD, user, tpath, (char *)NULL);
	syslog(LOG_ERR, "TMPDIR cleanup(%s): execl(%s) failed: %m",
	       tpath, CLEANTMPCMD);
	exit(1);
    default:
	/*
	 * Forget about child.  We will exit, and
	 * /etc/init will pick it up.
	 */
	break;
    }
}
#endif /* CRAY */
#endif	/* defined(PARENT_DOES_UTMP) */