--- loncom/clusteradmin	2009/02/02 11:58:59	1.1
+++ loncom/clusteradmin	2009/03/16 09:43:00	1.2
@@ -16,7 +16,7 @@ Furthermore, lonc must be running on thi
 The action is specified by the 'command' parameter which may have additional arguments.
 
 All communications with remote clients are made critical so that
-they will eventually happen even if the host we want to talk with
+they will eventually happen even if the147 host we want to talk with
 is dead.
 
 
@@ -37,11 +37,24 @@ on this system.  'file' is the name of t
 
 =back
 
+=head1 ASSUMPTIONS
+
+Assume that loncapa is installedin /home/httpd/lib/perl so that we can use
+it's modules.  If this is not the case, you mus modify the
+use lib line in the program before you can use it.
+
 
 =cut
 
 use strict;
 
+# I'm not sure if there's a better way to establish the location of the libs:
+
+use lib ('/home/httpd/lib/perl');
+
+use LONCAPA::Configuration;
+use File::Basename;
+use Apache::lonnet;
 
 #----------------------------------------------------------------------------------
 #
@@ -103,3 +116,168 @@ sub dispatch_command {
     }
 }
 #-----------------------------------------------------------------------------------
+
+#
+#  Provide usage/help string:
+#
+
+sub usage {
+    print STDERR "Usage:\n";
+    print STDERR "   clusteradmin subcommand [args]\n";
+    print STDERR "Where:\n";
+    print STDERR "   subcommand describes what to actually do:\n";
+    print STDERR "    help    - Prints this message (args ignored)\n";
+    print STDERR "    update  - Updates an administrative file\n";
+    print STDERR "              args is one of dns_hosts.tab or dns_domain.tab\n";
+
+}
+
+&define_command("help", \&usage);
+
+
+#--------------------------------------------------------------------------------
+#
+#  File update subsystem:
+
+
+# Given the basename of an administrative file, return the 
+# full path to that file.
+# Pre-requisistes:
+#   Requires that LONCAPA::Configuration is in the use lib path.
+# Parameters:
+#   $basename   - Base name of the file to locate.
+# Returns:
+#   Full path to that file.
+#
+
+my $config_vars = LONCAPA::Configuration::read_conf('loncapa.conf');
+my %config = %{$config_vars};
+
+
+sub construct_table_path {
+    my ($basename) = @_;
+    my $directory = $config{'lonTabDir'};
+
+    return $directory . '/' . $basename;
+}
+
+#  Returns the set of hosts that are specified as DNS hosts in the hosts.tab file.
+#  Those are the ones with a ^ in column one.
+#
+#  Returns:
+#    The list of host that are DNS hosts.
+#
+sub get_dns_hosts()
+{
+    my @result;
+    my $hosts_tab = &construct_table_path('hosts.tab');
+    open(HOSTS, "<$hosts_tab");
+    while (my $line = <HOSTS>) {
+	chomp($line);
+	if ($line =~ /^\^/) {
+	    $line =~ s/^\^//;           # Get rid of leading ^
+	    $line =~ s/\s*$//;          # and any trailing whitespace.
+	    push(@result, $line);
+	}
+    }
+    return (@result);
+}
+
+# Actually push the new files to the systems to update.  This is done as a critical
+# transaction so that the files eventually get pushed, even if the target hosts
+# are down about now.
+#
+# Parameters: 
+#   specifier     - The specifier to hand in the push transaction. This
+#                   identifies the target file in the remote lond process.
+#   pushfile     - Full path to the file to push.
+#   hosts         - Reference to an array of hosts into which the file should be pushed.
+#
+# Returns:
+#    1     - Success.
+#    0     - Failure with appropriate output to stderr.
+#
+sub push_file {
+    my ($specifier, $pushfile, $hosts) = @_;
+
+    # Read in the entire file:
+
+    my $contents;
+    my $line;
+    open(FILE, "<$pushfile");
+    while ($line = <FILE>) {
+	$contents .= $line;
+    }
+
+
+    # Construct the transaction for safety we encrypt the transaction
+    #
+    my $cmd = "encrypt:pushfile:$specifier:$contents";
+
+    # Iterate over the hosts and run cmd as a critical 
+    # operation:
+
+    foreach my $host (@$hosts) {
+	my $loncapa_name = &Apache::lonnet::host_from_dns($host);
+	my $reply  = &Apache::lonnet::critical($cmd, $loncapa_name);
+	if ($reply ne 'ok') {
+	    print STDERR "Reply from $host ($loncapa_name)  not 'ok' was: $reply\n";
+	}
+    }
+    
+}
+
+#
+#   Controls the push of a file to the servers that deserve to get it.
+# Parameters:
+#    args   - Tail of the command line (array reference).
+# Returns:
+#    1      - Success.
+#    0      - Failure (printing messages to stderr.
+#
+sub update_file {
+    my ($args) = @_;
+
+    if (scalar(@$args) != 1) {
+	print STDERR "Incorrect number of command arguments\n";
+	&usage();
+	return 0;
+    } else {
+	my $filename = shift(@$args);
+	
+	# Validate the filename:
+
+	if ($filename eq 'dns_hosts.tab' || $filename eq 'dns_domain.tab') {
+	    my $pushfile   = &construct_table_path($filename);
+	    my $specifier  = basename($filename, ('.tab'));
+	    my @hosts         = (&get_dns_hosts());
+	    return &push_file($specifier, $pushfile,  \@hosts);
+	} else {
+	    print STDERR "Only dns_hosts.tab or dns_domain.tab can be updated\n";
+	    &usage();
+	    return 0;
+	}
+    }
+}
+&define_command("update", \&update_file);
+#---------------------------------------------------------------------------------
+#
+#  Program entry point.  Decode the subcommand from the args array and
+#  dispatch to the appropriate command processor.
+#
+
+my $argc = scalar(@ARGV);
+if ($argc == 0) {
+    print STDERR "Missing subcommand\n";
+    &usage();
+    exit(-1);
+}
+
+my $subcommand = shift(@ARGV);     # argv now the tail.
+
+if (!&dispatch_command($subcommand, \@ARGV)) {
+    exit(0);
+} else {
+    exit(-1);
+}
+