#!/usr/bin/perl
# The LearningOnline Network with CAPA
#
#  lonManage supports remote management of nodes in a LonCAPA cluster.
#
#  $Id: lonManage,v 1.11 2003/08/18 10:45:32 foxr Exp $
#
# $Id: lonManage,v 1.11 2003/08/18 10:45:32 foxr Exp $
#
# Copyright Michigan State University Board of Trustees
#
# This file is part of the LearningOnline Network with CAPA (LON-CAPA).
## LON-CAPA is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# LON-CAPA is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with LON-CAPA; if not, write to the Free Software
# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
#
# /home/httpd/html/adm/gpl.txt
#
# http://www.lon-capa.org/
#
#
#   lonManage supports management of remot nodes in a lonCAPA cluster.
#   it is a command line tool.  The following command line syntax (usage)
#   is supported:
#
#    lonManage  -push   <tablename>  newfile  host
#        Push <tablename> to the lonTabs directory.  Note that
#        <tablename> must be one of:
#           hosts  (hosts.tab)
#           domain (domain.tab)
#
#    lonManage  -reinit lonc host
#           Sends a HUP signal to the remote systems's lond.
#
#    lonmanage  -reinit lond host
#          Requests the remote system's lond perform the same action as if
#          it had received a HUP signal.
#
#    In the above syntax, the host above is the hosts.tab name of a host,
#    not the IP address of the host.
#
#  $Log: lonManage,v $
#  Revision 1.11  2003/08/18 10:45:32  foxr
#  Felt strongly enough about hoisting ReadConfiguration into a separate sub
#  that I did it now before I forgot.
#
#  Revision 1.10  2003/08/18 10:43:31  foxr
#  Code/test ValidHost.  The hosts.tab and the perl variables are read in as
#  global hashes as a side effect.  May later want to clean this up by making
#  a separate getconfig function and hoisting the config reads into that.
#
#  Revision 1.9  2003/08/18 10:25:46  foxr
#  Write ReinitProcess function in terms of ValidHost and Transact.
#
#  Revision 1.8  2003/08/18 10:18:21  foxr
#  Completed PushFile function in terms of
#  - ValidHost - Determines if target host is valid.
#  - Transact  - Performs one of the valid transactions with the
#                appropriate lonc<-->lond client/server pairs.
#
#  Revision 1.7  2003/08/18 09:56:01  foxr
#  1. Require to be run as root.
#  2. Catch case where no operation switch is supplied and put out usage.
#  3. skeleton/comments for PushFile function.
#
#  Revision 1.6  2003/08/12 11:02:59  foxr
#  Implement command switch dispatching.
#
#  Revision 1.5  2003/08/12 10:55:42  foxr
#  Complete command line parsing (tested)
#
#  Revision 1.4  2003/08/12 10:40:44  foxr
#  Get switch parsing right.
#
#  Revision 1.3  2003/08/12 10:22:35  foxr
#  Put in parameter parsing infrastructure
#
#  Revision 1.2  2003/08/12 09:58:49  foxr
#  Add usage and skeleton documentation.
#
#

# Modules required:

use strict;			# Because it's good practice.
use English;			# Cause I like meaningful names.
use Getopt::Long;
use LONCAPA::Configuration;	# To handle configuration I/O.

# File scoped variables:

my %perlvar;			# Perl variable defs from apache config.
my %hostshash;			# Host table as a host indexed hash.

sub Usage  {
    print "Usage:";
    print <<USAGE;
    lonManage  --push=<tablename>  newfile  host
        Push <tablename> to the lonTabs directory.  Note that
        <tablename> must be one of:
           hosts  (hosts.tab)
           domain (domain.tab)

    lonManage  --reinit=lonc host
           Sends a HUP signal to the remote systems's lond.

    lonManage  --reinit=lond host
          Requests the remote system's lond perform the same action as if
          it had received a HUP signal.

    In the above syntax, the host above is the hosts.tab name of a host,
    not the IP address of the host.
USAGE


}

#
#  Use Getopt::Long to parse the parameters of the program.
#
#  Return value is a list consisting of:
#    A 'command' which is one of:
#       push   - table push requested.
#       reinit - reinit requested.
#   Additional parameters as follows:
#       for push: Tablename, hostname
#       for reinit: Appname  hostname
#
#   This function does not validation of the parameters of push and
#   reinit.
#
#   returns a list.  The first element of the list is the operation name
#   (e.g. reinit or push).  The second element is the switch parameter.
#   for push, this is the table name, for reinit, this is the process name.
#   Additional elements of the list are the command argument.  The count of
#   command arguments is validated, but not their semantics.
#
#   returns an empty list if the parse fails.
#

sub ParseArgs {
    my $pushing   = '';
    my $reinitting = '';

    if(!GetOptions('push=s'    => \$pushing,
	           'reinit=s'  => \$reinitting)) {
	return ();
    }

    #  Require exactly   one of --push and --reinit

    my $command    = '';
    my $commandarg = '';
    my $paramcount = @ARGV; 	# Number of additional arguments.
    

    if($pushing ne '') {

        # --push takes in addition a table, and a host:
        #
	if($paramcount != 2) {
	    return ();		# Invalid parameter count.
	}
	if($command ne '') {
	    return ();
	} else {
	    
	    $command    = 'push';
	    $commandarg = $pushing;
	}
    }

    if ($reinitting ne '') {

	# --reinit takes in addition just a host name

	if($paramcount != 1) {
	    return ();
	}
	if($command ne '') {
	    return ();
	} else {
	    $command    = 'reinit';
	    $commandarg = $reinitting; 
	}
    }

    #  Build the result list:

    my @result = ($command, $commandarg);
    my $i;
    for($i = 0; $i < $paramcount; $i++) {
	push(@result, $ARGV[$i]);
    }
    
    return @result;
}
#
#  Read the loncapa configuration stuff.
#
sub ReadConfig {
    my $perlvarref = LONCAPA::Configuration::read_conf('loncapa.conf');
    %perlvar       = %{$perlvarref};
    my $hoststab   = LONCAPA::Configuration::read_hosts(
					"$perlvar{'lonTabDir'}/hosts.tab");
    %hostshash     = %{$hoststab};

}
#
#  Determine if the target host is valid.
#  This is done by reading the current hosts.tab file.
#  For the host to be valid, it must be inthe file.
#
#  Parameters:
#     host   - Name of host to check on.
#  Returns:
#     true   if host is valid.
#     false  if host is invalid.
#
sub ValidHost {
    my $host       = shift;
   
    ReadConfig;

    return defined $hostshash{$host};

}
sub Transact {

}
#
#   Called to push a file to the remote system.
#   The only legal files to push are hosts.tab and domain.tab.
#   Security is somewhat improved by
#   
#   - Requiring the user run as root.
#   - Connecting with lonc rather than lond directly ensuring this is a loncapa
#     host
#   - We must appear in the remote host's hosts.tab file.
#   - The host must appear in our hosts.tab file.
#
#  Parameters:
#     tablename - must be one of hosts or domain.
#     tablefile - name of the file containing the table to push.
#     host      - name of the host to push this file to.     
#
sub PushFile {
    my $tablename = shift;
    my $tablefile = shift;
    my $host      = shift;
    
    # Open the table file:

    if(!open(TABLEFILE, "<$tablefile")) {
	die "ENOENT - No such file or directory $tablefile";
    }
  
    # Require that the host be valid:

    if(!ValidHost($host)) {
	die "EHOSTINVAL - Invalid host $host"; # Ok so I invented this 'errno'.
    }
    # Read in the file.  If the table name is valid, push it.

    my @table = <TABLEFILE>;	#  These files are pretty small.
    close TABLEFILE;

    if( ($tablename eq "host")    ||
	($tablename eq "domain")) {
	Transact($host, "pushfile:$tablename:",\@table);
    } else {
	die "EINVAL - Invalid parameter. tablename: $tablename must be host or domain";
    }
}
#
#   This function is called to reinitialize a server in a remote host.
#   The servers that can be reinitialized are:
#   - lonc   - The lonc client process.
#   - lond   - The lond daemon.
#  NOTE:
#    Reinitialization in this case means re-scanning the hosts table,
#    starting new lond/lonc's as approprate and stopping existing lonc/lond's.
#
#  Parameters:
#     process - The name of the process to reinit (lonc or lond).
#     host    - The host in which this reinit will happen.
#
sub ReinitProcess {
    my $process = shift;
    my $host    = shift;

    #  Ensure the host is valid:
    
    if(!ValidHost($host)) {
	die "EHOSTINVAL - Invalid host $host";
    }
    # Ensure target process selector is valid:

    if(($process eq "lonc") ||
       ($process eq "lond")) {
	Transact($host, "reinit:$process");
    } else {
	die "EINVAL -Invalid parameter. Process $process must be lonc or lond";
    }
}
#--------------------------- Entry point: --------------------------

#  Parse the parameters
#  If command parsing failed, then print usage:

my @params   = ParseArgs;
my $nparam   = @params;

if($nparam == 0) {
    Usage;
    exit -1;
}
#
#   Next, ensure we are running as EID root.
#
if ($EUID != 0) {
    die "ENOPRIV - No privilege for requested operation"
}


#   Based on the operation requested invoke the appropriate function:

my $operation = shift @params;

if($operation eq "push") {  # push tablename filename host
    my $tablename = shift @params;
    my $tablefile = shift @params;
    my $host      = shift @params;
    PushFile($tablename, $tablefile, $host);

} elsif($operation eq "reinit") {	# reinit processname host.
    my $process   = shift @params;
    my $host      = shift @params;
    ReinitProcess($process, $host);
}
else {
    Usage;
}
exit 0;

=head1 NAME
    lonManage - Command line utility for remote management of lonCAPA
    cluster nodes.

=head1 SYNOPSIS

Usage:
    B<lonManage  --push=<tablename>  newfile  host>
        Push <tablename> to the lonTabs directory.  Note that
        <tablename> must be one of:
           hosts  (hosts.tab)
           domain (domain.tab)

    B<lonManage  --reinit=lonc host>
           Sends a HUP signal to the remote systems's lond.

    B<lonmanage  --reinit=lond host>
          Requests the remote system's lond perform the same action as if
          it had received a HUP signal.

    In the above syntax, the host above is the hosts.tab name of a host,
    not the IP address of the host.


=head1 DESCRIPTION

=head1 PREREQUISITES

=item strict
=item Getopt::Long
=item English

=head1  CATEGORIES
    Command line utility

=cut
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