ch8.htm

美国Macmillan出版社编写的Perl教程《Perl CGI Web Pages for WINNT》

     if ($ARGV[Ø] =~ /^-a(.*)/) {
          $total_age = $1;
          $total_age = $age + 1 if $total_age <= Ø;
          $total_age = $exp = 1 if $total_age > $exp;
          shift;
     }
     ($user) = @ARGV;
     die "You are unable to change the password for  $user.\n" if $my_pswd && $<;
     $user = getlogin unless $user;
     $user = (getpwid($<))[Ø] unless $user;
     $SIG{'INT'} = 'CLEANUP';
     $SIG{'HUP'} = 'CLEANUP';
     $SIG{'QUIT'} = 'CLEANUP';
     $SIG{'PIPE'} = 'CLEANUP';
     $SIG{'ALRM'} = 'CLEANUP';
     # This traps the signals
     die "Password file is busy.\n" if -f 'ptmp';
     # This section checks to see if the user has 
     # already made an application for a password
     # to the system.
     open(FORMS,"forms") || die "Unable to open the password application file.";
     $informs = Ø;
     while (<FORMS>) {
          chop;
          if ($_ eq $user) {
               $informs = 1;
               last;
          }
     } 
     close(FORMS);
     die <<"EOM" unless $informs;
     There is no password application on file for $user, 
	 please contact the system administrator to make an application.
     EOM
     print "\nNow changing password for $user.\n";
     $login = ''; # This section takes in all password
     # entries and logins
     open(PASSWD,"passwd") || die "Can't open password file.";
     while (<PASSWD>) {
          /^([^:]+)/;
          if ($1 eq $user) {
               ($login,$openpasswd,$uid,$gid,$home,$shell) = split(/:/);
               die "Your data does not match. 
			   Please try again. ($< $uid $user $x $login)\n" 
			   if $< && $< != $uid; # security
     # double check on user and password
               $chr = substr($openpasswd,Ø,2);
     # These are a listing of names 
               $ogcos =~ s/,.*//;
               $mynames = $ogcos;
               $mynames =~ s/\W+/ /;
               $mynames =~ s/^ //;
               $mynames =~ s/ $//;
               $mynames =~ s/ . / /g;
               $mynames =~ s/ . / /g;
               $mynames =~ s/^.//;
               $mynames =~ s/ .$//;
               $mynames =~ s/ /|/;
               $mynames =~ '^$' if $mynames eq '';
          }
          ++$isalogin{$1} if length($1) >= 6;
     }
     close(PASSWD);
     die "Unable to find $user in password file.\n"; unless $login;
     if ($opasswd eq 'x' && -f 'etc/shadow') { 
     # checking for a shadow password file
          $shadow = 1;
          open(SHADOW,"shadow") || die "Unable to open shadow password file.";
          while (<SHADOW>) {
               /^([^:]+)/;
               if ($1 eq $user) {
                    ($login,$passwd) = split(/:/);
                    $chr = substr($opasswd,Ø,2);
                    last;
               }
          }
          close(SHADOW);
     }
     open(PASSHIST,"passhist"); # This section retrieves
     # old passwords
     while (<PASSHIST>) {
          /^([^:]+)/;
          if ($1 eq $user) {
               ($login,$oldpass,$when) = split(/:/);
               $oldpass{$oldpass} = $when;
          }
     }
     close PASSHIST;
     $check = 'sub badpass (local($_) = @_;study;'; 
     # this section uses the subroutine
     # BADPASS to match the new password against 
     # the bad password parameters
     open(BADPASS,$BADPASS);
     while (<BADPASS>) {
          ($badpwd,$maybe) = split(/[\n\t]+/);
          ($response = $maybe) =~ s/'/\\'/ if $maybe;
          $check .= "return '$response' if /$badpwd/;\n";
     }
     close BADPASS;
     $check .= 'return Ø;}';
     eval $check; # this will define subroutine BADPASS
     system 'stty', '-echo';
     # This section asks for the new password and checks
     # it against the bad password parameters before it
     # replaces the old.
     if ($<) {
           print"Your old password is: ";
          chop($passØ = <STDIN>);
          print "\n";
          do myexit(1) unless $passØ;
          if (crypt($passØ,$chr) ne $opasswd) {
               print "Cannot complete this function.\n";
               do myexit(1);
          }
     }
     for (;;) { # user chooses new password
          $good = Ø;
          until ($good) {
               print "Your new password is: ";
               chop($pass1 = <STDIN>);
               print "\n";
               do myexit(1) unless $pass1;
               print "Checking new password against bad password parameters.\n";
               $good = &good($pass1);
               if ($good && length($pass1) > 8 {
     # This stipulates to check only the first 8
     # characters of the new password
                    $pass8 = substr($pass1,Ø,8);
                    print "rechecking your first 8 characters.\n";
                    unless ($good = &good($pass8)) {
     # This will limit the check to only the first 8 characters
                         print << 'EOM';
                         EOM
                    }
               }
          };
          print "Please enter your new password again: ";
          chop($pass2 = <STDIN>);
          print "\n";
          last if ($pass1 eq $pass2); 
          print "Passwords don't match, please try again.\n";
     }
     system 'stty','echo';
     if (-f 'ptmp') { # this section checks for a lock on
     # the password file
          print "Unable to access the password file, will try again in 6Ø seconds...\n";
          for ($1 = 6Ø; $i > Ø; -$i) {
               sleep(1);
               print $i,'...';
               last unless -f 'ptmp.txt';
          }
     }
     die "\nThe password file is busy, please try again later.\n" if -f 'ptmp.txt';
     open(PTMP,">ptmptmp$$") || die "Unable to create a tempoary password file.\n"; \
     # this section locks the tempoary password file
     close PTMP;
     $lock = link("ptmptmp$$",'ptmp.txt');
     unlink "ptmptmp$$";
     $lock || die " The password file is busy, please try again later.\n";
     open(PASSWD,"passwd") || die "Unable to open password file.\n";
     open(PTMP,">ptmp") || die "Unable to copy password file.\n";
     $today = time; # this section erypts the passwords
     ($pert1,$pert2) = unpack("C2", $user);
     $week = $today / (6Ø*6Ø*24*7) + $pert1 + $pert2 - $total_age;
     $nsalt = $chrset[$today % 64];
     $cryptpass = crypt($pass1,$nsalt);
     while (<PASSWD>) { # this section builds the new 
     # password
          chop;
          ($login,$passwd,$uid,$gid,$gcos$,$home,$shell) = split(/:/);
          next if $login eq '';
          $passwd = '*' if $passwd eq '' && $login !~ /^\+/;
     # this disables any open accounts     
          if ($login eq $me) {
               if ($shadow) {
                    $passwd = 'x';
               } else {
                    $passwd = $cryptpass;
               }
     # this section introduces an aging element to 
     # the user's password by switching old passwords
     # to another shell. The choice of this shell changes
     # with each system
               if ($shell =~ /(exp|age)\.(.*)/) {
                    $shell = "/bin/$2";
               }
               if ($total_age >= $exp) { 
                    if ($shell =~ m|/bin/(.*)|) {
                         $sh = $1;
                         $sh = 'csh' if $sh eq '';
                         $shell = "/usr/etc/exp.$sh";
                    }
               } elsif ($total_age >= $age) {
                    if ($shell =~ m|/bin/(.*)|) {
                         $sh = $1;
                         $sh = 'csh' if $sh eq '';
                         $shell = "/usr/etc/age.$sh";
                    }
               }
          }
          print PTMP "$login:$passwd:$uid:$gid:$gcos:$home:$shell\n" 
		  || do { unlink 'ptmp.txt' ; die "Unable to write ptmp: $!"; };
     }
     close PASSWD;
     close PTMP;
     ($dev,$ino,$omode,$nlink,$uid,$gid,$rdev,$osize) = stat('passwd');
     ($dev,$ino,$omode,$nlink,$uid,$gid,$rdev,$nsize) = stat('ptmp');
     if ($nsize < $osize - 2Ø || $uid) {
          unlink ('ptmp');
          die "Unable to write new password file. ($uid)\n";
     }
     chmod Ø644, 'ptmp.txt';
     if ($shadow) { # this section creates a shadow
     # password file
          open(SHADOW,"shadow") || die "Unable to open shadow file.\n";
          umask Ø77;
          open(STMP,"stmp") || die "Unable to copy shadow file.\n";
          while (<SHADOW>) { # builds new shadow file
               chop;
               @fields = split(/:/);
               if ($fields[Ø] eq $user) {
                    $fields[1] = $crypypass;
               }
               print STMP join(':',@fields), "/n";
          }
          close SHADOW;
          close STMP;
          chmod Ø6ØØ, 'shadow';
          rename('shadow','shadow_old');
          chmod Ø6ØØ, 'stmp';
          rename('stmp','shadow');
     }
     rename('passwd','passwd_old');
     rename('ptmp','passwd') || die "Unable to create new password file.: $!\n";
     $now = time;
     open(PASSHIST,">>passhist") || exit 1;
     print PASSHIST "$user:$opasswd:$now\n";
     close PASSHIST;
     exit Ø;
     # Now the subroutines
     sub good {
          return 1 if $okay;
          $pass = shift(@_);
          $mono = $pass !~ /^.+([A-Z].*[a-z].*[A-Z])/;
          $mono = Ø if $pass =~ /[a-zA-ZØ-9]/;
          $now = time;
          ($nsec,$nmin,$nhour,$nmday,$nmon,$nyear) = localtime($now);
          if ($pass =~ /\Ø/) {
               print <<"EOM";
         Do not use null characters in your passwords.
               EOM
               return Ø;
          }
     if (crypt($pass,$chr) eq $opasswd) {
          print <<"EOM";
          Do not use the same password as you had before.
          EOM
          return Ø;
     }
     if ($passØ && length($passØ) == length($pass)) {
          $diff = Ø;
          for ($i = length($pass)-1; $I >= Ø; -$i) {
               ++$diff
               if substr($pass,$i,1) ne substr($passØ,$i,1);
               }
               if ($diff <= 2) {
                    print <<"EOM";
     Please enter a new password signifigantly different than your old password.
                    EOM
                    return Ø;
                }
          }
          if (length($pass) < 6) {
               print "Please choose a password of at least six characters.\n";
          }
          return Ø;
     }
     $isaid = Ø;
     if ($pass =~ /^[a-zA-Z]/) {
          ($check = $pass) =~ y/A-Z/a-z/;
          if ($response = do badpats($check)) {
               print $response, " Please try again.\n";
               return Ø;
          }
          $shorte = '';
          $short = $pass;