Re: [cobalt-developers] REMOTE_USER variable

[Martin Sojka <msojka-cobalt@xxxxxx>]

Hello,

> I am using a .htaccess file to protect a directory/site .  Using
> perl/cgi I can obtain the REMOTE_USER variable and store or display this
> information.  What I would like to do is display all users that are
> currently authenticated to this resource. So in effect I want to display
> not only the logged in users REMOTE_USER variable but all REMOTE_USER
> variables that are currently logged in. Is this possible? Is anyone
> doing something similar?

Well, http doesn't support permanent connections like telnet or ssh do... 
anyway, you could log all authenticated requests, together with a 
timestamp, and drop any lines older then 5 minutes (or so). A simple perl 
script would look like this (usage: "@logged_in_users = 
get_users($ENV{'REMOTE_USER'});" or simply "... = get_users();").

my $lock_file = "users.lock";
my $users_file = "users";

sub get_users(;$)
{
  my ($new_user) = @_;
  my @new_udata = ();
  my @authenticated = ();

  lock_users();
  if( open(USERS, "<${users_file}") )
  {
    my @udata = <USERS>;
    close(USERS);

    foreach my $user_data (@udata)
    {
      chop $user_data;
      if( $user_data =~ /^([a-zA-Z0-9]+):([0-9]+)$/ )
      {
        my $user_name = $1; my $time_stamp = $2;
        if( $time_stamp >= time() && $user_name ne $new_user )
        {
          push(@new_udata, "${user_name}:${time_stamp}\n");
          push(@authenticated, $user_name);
        }
      }
    }
    if( defined($new_user) )
    {
      # Add this user
      push(@new_data, sprintf("%s:%d\n", $new_user, time() + 5*60));
      push(@authenticated, $new_user);
    }
    if( open(USERS, ">${users_file}") )
    {
      print(USERS @new_udata);
      close(USERS);
    }
    else
    {
      error("Couldn't write to ${users_file}: $!\n"); # error() defined 
elsewhere
    }
  }
  else
  {
    error("Couldn't open ${users_file}: $!\n"); # error() defined elsewhere
  }
  unlock_users();
  return(@authenticated);
}

sub lock_users()
{
  while(-e($lock_file))
  {
    select(undef, undef, undef, 0.1); # wait 0.1s
  }
  if(open(LOCK, ">${lock_file}"))
  {
    print(LOCK "$$\n");
    close(LOCK);
  }
  else
  {
    die("Couldn't open ${lock_file}: $!\n");
  }
}

sub unlock_users()
{
  if(-e($lock_file))
  {
    unlink($lock_file);
  }
}

Ok, so it's not perfect. I would recommend to at least define $SIG{'PIPE'} 
to something meaningful, and to define error(), of course. Maybe there 
should be a timeout in lock_users() (it can wait forever...), and some way 
to deal with a lock file from a killed/aborted process - for example, you 
could check if the process with the pid from $lock_file is actually still 
running.

Read you...
       Martin Sojka.