deslogind.c

一个使用des加密传输的unix下的login程序的服务器端和客户端

      cpuUsed   = cpuTime();
      loginTime = time((time_t *) 0) - loginTime;

      if (res != 0) {
	 log(
	    "%s: Logout %s on %u(%ld%c%ld) sec(CPU), %lu/%lu bytes in/out\n",
	    progName, userName, loginTime, cpuUsed / 10, '.', cpuUsed % 10, 
	    inBytes, outBytes);
      } else {
	 log(
"%s: Logout %s on %u(%ld%c%ld) sec(CPU), %lu/%lu bytes in/out (idle %u sec)\n",
	    progName, userName, loginTime, cpuUsed / 10, '.', cpuUsed % 10, 
	    inBytes, outBytes, connTimeout / 1000);
      }
      exit(0);
   }

   /* child */
   setProgName();

   if (generic) {
      cargv[1] = loginArg1;
      cargv[2] = rhostName;
   } else {
      tz = getenv("TZ");	/* may fail by returning NULL; OK though */
      if (uid == 0) {		/* root user gets special path */
	 path = SYSTEMPATH;
      }
      cenv = setupEnv(userName, shell, cwd, path, tz, rhostName);

      res = chdir(cwd);
      if (res != 0) {
	 log("%s: chdir to %s failed \"%s\"--%s\n", progName, cwd, ERRMSG);
	 return 1;
      }
      oldmask = umask(newmask);	/* documentation says umask cannot fail! */

      /*
       * This code must be placed only in the child because of the atexit call
       * in the parent for updating utmp.  This changes the uid, and gid now.
       */
      setupUser(uid, gid, userName);	/* exits if failure */
   }

   if ((chp = strrchr(shell, '/')) == (char *) 0) chp = shell-1;
   chp++;
   arg0	= (char *) malloc(strlen(chp)+2);
   if (arg0 == (char *) 0) {
      log("%s: couldn't allocate %d bytes for arg0\n", 
	 progName, strlen(chp)+2);
      exit(1);
   }
   arg0[0] = '-';				/* make this a login shell */
   memcpy(&arg0[1], chp, strlen(chp)+1);
   cargv[0] = arg0;

   /*
    * Sect4.3.2:157-177:
    * If the calling process is not a process group leader, the setsid()
    * function shall create a new session. The calling process shall be
    * the session leader of this new session, shall be be the process
    * group leader of a new process group, and shall have no controlling
    * terminal. The process group ID of the calling process shall be
    * set equal to  the process ID of the calling process.  The calling
    * process shall be the only process in the new proccess group and the
    * only process in the new session.
    *    Upon successful completion, the setsid() function returns the value
    * of the process group ID of the calling process.  Otherwise, a value of
    * -1 is returned and errno is set to indicate the error.
    * 
    * EPERM - The calling process is already a process group leader, or
    *         the process group ID of a process other than the calling process
    *         matches the process id of the calling process
    *
    * D.A.B.: the fork() made sure that pgid != pid, and
    *         we're not a pg leader because we didn't call setpgid.
    *
    * NOTE: getpgrp() expects an argument on BSD, but not POSIX.  If
    *       if you have BSD, (DEC MIPS, SunOS4.1), you should pass it 0.
    */
   if (debug > 1) {
      log("%s: getpid:  %ld\n", progName, (long) getpid());
      log("%s: getpgrp: %ld\n", progName, (long) getpgrp());
   }
   pid = setsid();	      /* break control terminal affiliation; get sid */
   /* 
    * Any open of a terminal device after setsid without O_NOCCTY will likely
    * become the controlling terminal.  
    */
   if (pid == -1) {
      log("%s: setsid failed--%s\n", progName, ERRMSG);
      return 1;
   }
   if (debug > 1) {
      log("%s: setsid:  %ld\n", progName, (long) pid);
      log("%s: getpid:  %ld\n", progName, (long) getpid());
      log("%s: getpgrp: %ld\n", progName, (long) getpgrp());
   }

   close(0);		/* actually, we should close ALL fd's here */
   close(1);		/* this should be all of them */
   close(2);		/* we made sure none of these are needed below */
   close(nfd);		/* they must be free for dup's to work */
   if (pty) {
      close(masterpty);
   /* 
    * This was designed to prevent someone from hooking upto the slave before
    * the child could.  It doesn't.  I've moved the close before the fork.
    */
#if 0
      /* must be as close as possible to the open 
       * to reduce the race condition for someone hijacking the slave pty
       * before this process can get it.  There needs to be a better way.
       *
       * There was a bug here if the parent still opened the slave as
       * a controlling terminal, and it hasn't closed slavepty before we do
       * here.  That's why O_NOCTTY is specified to openPty above.
       */
      close(slavepty);	
#endif
      /*
       * Sect7.2.3:753-765:
       * Upon successful completion, tcgetpgrp() returns the process group ID 
       * of the foreground process group associated with the terminal.  If 
       * there is no foreground process group, tcgetpgrp() shall return a value
       * greater than 1 that does not match the process group ID of any 
       * existing process group.  Otherwise, a value of -1 is returned and 
       * errno is set to indicate the error.
       *
       * EBADF  - The filedes argument is not a valid file descriptor
       * ENOSYS - The tcgetprgp() function is not supported in this 
       *          implementation
       * ENOTTY - The calling process does not have a controlling terminal,
       *          or the file is not the controlling terminal.
       */
      /*
       * Establish a new control terminal by being the first process without
       * a controlling terminal to open a tty device.  Non-POSIX, but
       * very common.
       *
       * The close must happen as close as possible with the open to prevent
       * hijacking of the slave side of the pty.  Note that on some systems
       * this may cause the master to get notified and abort prematurely.  I
       * don't think this exists now because of SIGCHLD being used instead.
       *
       * AnnexB:3884-3887:
       * POSIX.1 does not specify a mechanism by which to allocate a 
       * controlling terminal...Historical implementations allocate controlling
       * terminals on certain open() calls...Some historical implementations 
       * deallocate a controlling terminal on its last systemwide close.
       * This behavior is neither required nor prohibited.  Even on 
       * implementations that do provide this behavior, applications cannot
       * depend on it due to its systemwide nature.  
       *
       * Sect5:204-206: O_NOCTTY if set, and path identifies a terminal device,
       * the open() function shall not cause the terminal device to become the
       * controlling terminal for the process (see 7.1.1.3)
       *
       * Sect7.1.1.3:42-68:
       * ...The controlling terminal for a session is allocated by the session
       * leader in an implementation-defined manner.  If a session leader has
       * no controlling terminal and opens a terminal device file that is not
       * already associated with a session without using the O_NOCTTY option
       * (see 5.3.1), it is implementation defined whethere the terminal
       * becomes the controlling terminal of the session leader.  If a process
       * that is not a session leader opens a terminal file, or the O_NOCTTY
       * option is used on open(), that terminal shall not become the the 
       * controlling terminal of the calling process.  When a controlling
       * terminal becomes associated with a session, its foreground process
       * group shall be set to the process group of the session leader.
       *    The controlling terminal is inherited by the child process during a
       * fork() function call.  A process relinquishes its controlling terminal
       * when it creates a new session with the setsid() function; other 
       * processes remaining in the old session that had this terminal as
       * their controlling terminal continue to have it.  Upon the close of
       * the last file descriptor in the system (whether or not it is in the
       * current session) associated with the cntrolling terminal, it is 
       * unspecified whether all process that had the terminal cease to have
       * any controlling terminal.  Whether and how a session leader can
       * reacquire a controlling terminal after the controlling terminal has
       * been relinquished in this fashion is unspecified. A process does not
       * relinquish its controlling terminal simply by closing all of its
       * file descriptiors associated with the controlling terminal if other
       * processes continue to have it open.
       *    When a controlling process terminates, the controlling terminal
       * is disassociated from the current session, allowing it to be acquired
       * by a new session leader.  Subsequent access to the terminal by other
       * processes in the earlier session may be denied, with attempts to
       * access the terminal treated as if a modem disconnect had been sensed.
       * 
       * Sect7.2.4:775-800
       * If the process has a controlling terminal, the tcsetpgrp() function
       * shall set the foreground process group ID associated with the 
       * terminal to pgrp_id.  The file associated with filedes must be the 
       * controlling terminal of the calling process, and the controlling 
       * terminal must be currently associated with the session of the 
       * calling process.  The value of pgrp_id must match a process 
       * group ID of a process in the same session as the calling process.
       *     Upon successful completion, tcsetpgrp() returns a value of zero.
       * Othewise, a value of -1 is returned, and errno is set to indicate the
       * error.
       * EBADF  - The filedes argument is not a valid file descriptor.
       * EINVAL - The value of pgrp_id argument is not supported by the
       *	  implementation.
       * ENOSYS - The tcsetpgrp() function is not supported in this
       *	  implementation.
       * ENOTTY - The calling process does not have a controlling terminal, or
       *	  the file is not the controlling terminal, or the controlling
       *	  terminal is no longer associated with the session of the
       *	  calling process.
       * EPERM  - The value of pgrp_id is a value supported by the
       *	  implementation, but does not mmatch the process group ID of a
       *	  process in the same session as the calling process.
       *
       * HP-UX_9.0:termio(7) man page states:
       * A terminal can belong to a process as its controlling terminal.  Each
       * process of a session that has a controlling terminal has the same
       * controlling terminal.  A terminal can be the controlling terminal for
       * at most one session.  The controlling terminal for a session is
       * allocated by the session leader.	If a session leader has no
       * controlling terminal and opens a terminal device file that is not
       * already associated with a session without using the O_NOCTTY option
       * (see open(2), the terminal becomes the controlling terminal of the
       * session and the controlling terminal's foreground process group is set
       * to the process group of the session leader.  While a controlling
       * terminal is associated with a session, the session leader is said to
       * be the controlling process of the controlling terminal.
       *    The controlling terminal is inherited by a child process during a
       * fork() (see fork(2)).  A process relinquishes its controlling terminal
       * if it creates a new session with setsid() or setpgrp() (see setsid(2)
       * and setpgrp(2)), or when all file descriptors associated with the
       * controlling terminal have been closed.
       *    When the controlling process terminates, the controlling terminal is
       * disassociated from the current session, allowing it to be acquired by
       * a new session leader.  A SIGHUP signal is sent to all processes in the
       * foreground process group of the controlling terminal.  Subsequent
       * access to the terminal by other processes in the earlier session can
       * be denied (see Terminal Access Control) with attempts to access the
       * terminal treated as if a modem disconnect had been sensed.
       *
       * Ultrix4.3pty(4): The slave device can be opened multiple times, while
       * the master half can be opened only once.  [EIO] An attempt to open
       * the slave side of the pty was made before opening the master side of 
       * the pty.
       */
      sin = openSlavePty(sname, O_RDWR);
      if (sin < 0) {
	 log("%s: open slave pty \"%s\" for read-write failed--%s\n", 
	    progName, sname, ERRMSG);
	 exit(1);		/* sends SIGCHLD to parent */
      }
      res = mkCtrlTty(sin, 1);
      if (debug > 1) {
	 log("%s: mkCtrlTty(%d, %d) returned %d\n", 
	    progName, sin, 1, res);
      }
      if (res < 0) {
         log(
	    "%s: mkCtrlTty(%d) didn't acquire %s as contrlling terminal--%s\n",
	    progName, sin, sname, ERRMSG);
	 exit(1);
      }
      res  = tcsetpgrp(sin, pid);
      if (debug > 1) {
	 log("%s: tcsetpgrp(%d, %d) returned %d\n", 
	    progName, sin, pid, res);
      }
      if (res < 0) {
	 log("%s: could not acquire fd %d (%s) as controlling terminal--%s\n",
	    progName, sin, sname, ERRMSG);
	 exit(1);
      }
      res = setTtyAscii(sin);		/* initialize modes for ASCII I/O */
      res = mkReady(sin, buf, 1, SETUP_TIMEOUT);
      if (debug > 1) {
	 log("%s: mkReady(%d,%d)=%d\n", 
	    progName, sin, SETUP_TIMEOUT, res);
      }
      if (res < 0) {
	 log("%s: slave pty handshake failed--%s\n", progName, ERRMSG);
	 exit(1);
      }
      if (res == 0) {
	 log("%s: slave pty handshake failed.\n", progName);
	 exit(1);
      }

      sout = dupFd(sin, sname, O_WRONLY);
      serr = dupFd(sin, sname, O_RDWR);
      res  = fcntl(sin, F_SETFL, O_RDONLY);
      if (res < 0) {
	 log("%s: fcntl of \"%s\" for read-only failed--%s\n", 
	    progName, sname, ERRMSG);
	 exit(1);
      }
      if (debug > 1) {
         log("%s: STDIN = %d, STDOUT = %d, STDERR = %d\n", 
	    progName, sin, sout, serr);
      }
      /*
       * Make sure open(ctermid(NULL)) works.
       *
       * If you get a compile time error here on linux, it's because linux 
       * forgot to add an extern for ctermid in unistd.h.  Fix your include 
       * file or add "extern char *ctermid();" above.  Hopefully, linux will 
       * fix this error in the next release.  
       */
      chp = ctermid((char *) 0);	/* In POSIX <unistd.h> */
      if (chp == (char *) 0 || *chp == (char) 0) {
	 log("%s: WARNING--ctermid(0) failed --%s\n", progName, ERRMSG);
      } else {
	 ttyfd = open(chp, O_RDWR);
	 if (ttyfd == -1) {
	    log("%s: WARNING--open(\"%s\", O_RDWR) failed --%s\n", 
	       progName, chp, ERRMSG);
	 }
	 close(ttyfd);
      }
      /* 
       * Make sure getlogin works.  If not, setlogin didn't work.  You will
       * need to repair setlogin.c.  This call can still fail if the parent
       * still hasn't called setlogin by now.
       */
      chp = (char *) getlogin();
      if (chp == (char *) 0) {
	 log("%s: WARNING--getlogin returned NULL\n", progName);
      } else {
	 if (debug > 1) {
	    log("%s: getlogin returned \"%s\"\n", progName, chp);
	 }
      }
   } else {		/* pipe */
      close(pipe0[0]);
      close(pipe1[1]);

      sin  = dupFd(pipe1[0], "pipe1[0]", O_RDONLY);
      close(pipe1[0]);

      sout = dupFd(pipe0[1], "pipe0[1]", O_WRONLY);
      close(pipe0[1]);

      serr = dupFd(sin, "serr", O_RDWR);
   }

   /*
    * Effect of exec:
    *
    * Unchanged:
    *    POSIX State:
    *       open files and state (including locks)
    *       pid, pgid, ppid, sid, ruid, rgid,
    *
    *       chroot(), chdir(), umask(), getlogin(), ctermid()
    *       getgroups()
    *       times()
    *       alarm(), sigpending(), sigprocmask(), 
    *
    * Note that fork() updates:
    *       pid, ppid, times(), alarm(), sigpending(), file locks,
    *       own copy of fd's, directory streams; alarm cleared.
    *
    *    Non-posix state:
    *       ptrace(), semop().
    *       ulimit() nice() rtprio()
    *       semop() 
    *       ptrace() 
    *       setitimer()
    *
    * Changed:
    *    euid, egid, suid, sgid - changed if exec file has setuid/gid
    *    caught signals are set to SIG_DFL
    *
    *    shmop(2)  - none attached
    *    profil(2) - profiling disabled
    */
   if (debug) {
      if (generic) {
	 log("%s: exec \"%s\" as \"%s %s %s\"\n", progName, shell, 
	    cargv[0], cargv[1], cargv[2]);
      } else {
	 log("%s: exec \"%s\" as \"%s\"\n", progName, shell, cargv[0]);
      }
      if (debug > 1) {
	 log("%s: env:\n", progName);
	 showEnv("   ", cenv);
      }
   }
   closeLog();
   
   res  = execve(shell, cargv, cenv);
   if (res < 0) {
      return 1;
   }

   return 0;
}