--- loncom/Attic/lonc	2001/08/30 20:02:28	1.17
+++ loncom/Attic/lonc	2003/03/27 23:00:28	1.49
@@ -5,6 +5,30 @@
 # provides persistent TCP connections to the other servers in the network
 # through multiplexed domain sockets
 #
+# $Id: lonc,v 1.49 2003/03/27 23:00:28 albertel 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/
+#
 # PID in subdir logs/lonc.pid
 # kill kills
 # HUP restarts
@@ -13,14 +37,18 @@
 # 6/4/99,6/5,6/7,6/8,6/9,6/10,6/11,6/12,7/14,7/19,
 # 10/8,10/9,10/15,11/18,12/22,
 # 2/8,7/25 Gerd Kortemeyer
-# 12/05 Scott Harrison
 # 12/05 Gerd Kortemeyer
-# 01/10/01 Scott Harrison
-# 03/14/01,03/15,06/12 Gerd Kortemeyer
-# 
+# YEAR=2001
+# 03/14/01,03/15,06/12,11/26,11/27,11/28 Gerd Kortemeyer
+# YEAR=2002
+# 2/19/02,02/22/02,02/25/02 Gerd Kortemeyer
+# 3/07/02 Ron Fox 
 # based on nonforker from Perl Cookbook
 # - server who multiplexes without forking
 
+use lib '/home/httpd/lib/perl/';
+use LONCAPA::Configuration;
+
 use POSIX;
 use IO::Socket;
 use IO::Select;
@@ -29,39 +57,29 @@ use Socket;
 use Fcntl;
 use Tie::RefHash;
 use Crypt::IDEA;
+#use Net::Ping;
+use LWP::UserAgent();
 
-# grabs exception and records it to log before exiting
-sub catchexception {
-    my ($signal)=@_;
-    $SIG{'QUIT'}='DEFAULT';
-    $SIG{__DIE__}='DEFAULT';
-    &logthis("<font color=red>CRITICAL: "
-     ."ABNORMAL EXIT. Child $$ for server $wasserver died through "
-     ."\"$signal\" with this parameter->[$@]</font>");
-    die($@);
-}
-
-$childmaxattempts=5;
-
+$status='';
+$lastlog='';
+$conserver='SHELL';
+$DEBUG = 0;			# Set to 1 for annoyingly complete logs.
+$VERSION='$Revison$'; #' stupid emacs
+$remoteVERSION;
 # -------------------------------- Set signal handlers to record abnormal exits
 
-$SIG{'QUIT'}=\&catchexception;
+&status("Init exception handlers");
+$SIG{QUIT}=\&catchexception;
 $SIG{__DIE__}=\&catchexception;
 
-# ------------------------------------ Read httpd access.conf and get variables
-
-open (CONFIG,"/etc/httpd/conf/access.conf") || die "Can't read access.conf";
-
-while ($configline=<CONFIG>) {
-    if ($configline =~ /PerlSetVar/) {
-	my ($dummy,$varname,$varvalue)=split(/\s+/,$configline);
-        chomp($varvalue);
-        $perlvar{$varname}=$varvalue;
-    }
-}
-close(CONFIG);
+# ---------------------------------- Read loncapa_apache.conf and loncapa.conf
+&status("Read loncapa.conf and loncapa_apache.conf");
+my $perlvarref=LONCAPA::Configuration::read_conf('loncapa.conf');
+my %perlvar=%{$perlvarref};
+undef $perlvarref;
 
 # ----------------------------- Make sure this process is running from user=www
+&status("Check user ID");
 my $wwwid=getpwnam('www');
 if ($wwwid!=$<) {
    $emailto="$perlvar{'lonAdmEMail'},$perlvar{'lonSysEMail'}";
@@ -89,8 +107,12 @@ open (CONFIG,"$perlvar{'lonTabDir'}/host
 while ($configline=<CONFIG>) {
     my ($id,$domain,$role,$name,$ip)=split(/:/,$configline);
     chomp($ip);
-    $hostip{$id}=$ip;
+    if ($ip) {
+     $hostip{$id}=$ip;
+     $hostname{$id}=$name;
+    }
 }
+
 close(CONFIG);
 
 # -------------------------------------------------------- Routines for forking
@@ -102,104 +124,20 @@ close(CONFIG);
 %childatt               = ();       # number of attempts to start server
                                     # for ID
 
-sub REAPER {                        # takes care of dead children
-    $SIG{CHLD} = \&REAPER;
-    my $pid = wait;
-    my $wasserver=$children{$pid};
-    &logthis("<font color=red>CRITICAL: "
-     ."Child $pid for server $wasserver died ($childatt{$wasserver})</font>");
-    delete $children{$pid};
-    delete $childpid{$wasserver};
-    my $port = "$perlvar{'lonSockDir'}/$wasserver";
-    unlink($port);
-}
-
-sub HUNTSMAN {                      # signal handler for SIGINT
-    local($SIG{CHLD}) = 'IGNORE';   # we're going to kill our children
-    map {
-        $wasserver=$children{$_};
-        &logthis('Closing '.$wasserver.': '.&subreply('exit',$wasserver));
-	kill ('INT',$_);
-    } keys %children;
-    my $execdir=$perlvar{'lonDaemons'};
-    unlink("$execdir/logs/lonc.pid");
-    &logthis("<font color=red>CRITICAL: Shutting down</font>");
-    exit;                           # clean up with dignity
-}
-
-sub HUPSMAN {                      # signal handler for SIGHUP
-    local($SIG{CHLD}) = 'IGNORE';  # we're going to kill our children
-    map {
-        $wasserver=$children{$_};
-        &logthis('Closing '.$wasserver.': '.&subreply('exit',$wasserver));
-	kill ('INT',$_);
-    } keys %children;
-    &logthis("<font color=red>CRITICAL: Restarting</font>");
-    unlink("$execdir/logs/lonc.pid");
-    my $execdir=$perlvar{'lonDaemons'};
-    exec("$execdir/lonc");         # here we go again
-}
-
-sub USRMAN {
-    &logthis("USR1: Trying to establish connections again");
-    foreach $thisserver (keys %hostip) {
-	$answer=subreply("ping",$thisserver);
-        &logthis("USR1: Ping $thisserver "
-        ."(pid >$childpid{$thisserver}<, $childatt{thisserver} attempts): "
-        ." >$answer<");
-    }
-    %childatt=();
-}
-
-# -------------------------------------------------- Non-critical communication
-sub subreply { 
- my ($cmd,$server)=@_;
- my $answer='';
- if ($server ne $perlvar{'lonHostID'}) { 
-    my $peerfile="$perlvar{'lonSockDir'}/$server";
-    my $sclient=IO::Socket::UNIX->new(Peer    =>"$peerfile",
-                                      Type    => SOCK_STREAM,
-                                      Timeout => 10)
-       or return "con_lost";
-    print $sclient "$cmd\n";
-    my $answer=<$sclient>;
-    chomp($answer);
-    if (!$answer) { $answer="con_lost"; }
- } else { $answer='self_reply'; }
- return $answer;
-}
-
-# --------------------------------------------------------------------- Logging
-
-sub logthis {
-    my $message=shift;
-    my $execdir=$perlvar{'lonDaemons'};
-    my $fh=IO::File->new(">>$execdir/logs/lonc.log");
-    my $now=time;
-    my $local=localtime($now);
-    print $fh "$local ($$): $message\n";
-}
-
-
-sub logperm {
-    my $message=shift;
-    my $execdir=$perlvar{'lonDaemons'};
-    my $now=time;
-    my $local=localtime($now);
-    my $fh=IO::File->new(">>$execdir/logs/lonnet.perm.log");
-    print $fh "$now:$message:$local\n";
-}
+$childmaxattempts=5;
 
 # ---------------------------------------------------- Fork once and dissociate
-
+&status("Fork and dissociate");
 $fpid=fork;
 exit if $fpid;
 die "Couldn't fork: $!" unless defined ($fpid);
 
 POSIX::setsid() or die "Can't start new session: $!";
 
-# ------------------------------------------------------- Write our PID on disk
+$conserver='PARENT';
 
+# ------------------------------------------------------- Write our PID on disk
+&status("Write PID");
 $execdir=$perlvar{'lonDaemons'};
 open (PIDSAVE,">$execdir/logs/lonc.pid");
 print PIDSAVE "$$\n";
@@ -212,42 +150,69 @@ $SIG{HUP}=$SIG{USR1}='IGNORE';
     
 # Fork off our children, one for every server
 
+&status("Forking ...");
+
 foreach $thisserver (keys %hostip) {
-    make_new_child($thisserver);
+    #if (&online($hostname{$thisserver})) {
+       make_new_child($thisserver);
+    #}
 }
 
 &logthis("Done starting initial servers");
 # ----------------------------------------------------- Install signal handlers
 
-$SIG{CHLD} = \&REAPER;
+
 $SIG{INT}  = $SIG{TERM} = \&HUNTSMAN;
 $SIG{HUP}  = \&HUPSMAN;
 $SIG{USR1} = \&USRMAN;
 
 # And maintain the population.
 while (1) {
-    sleep;                          # wait for a signal (i.e., child's death)
-                                    # See who died and start new one
-    foreach $thisserver (keys %hostip) {
-        if (!$childpid{$thisserver}) {
-	    if ($childatt{$thisserver}<$childmaxattempts) {
-	       $childatt{$thisserver}++;
-               &logthis(
-   "<font color=yellow>INFO: Trying to reconnect for $thisserver "
-  ."($childatt{$thisserver} of $childmaxattempts attempts)</font>"); 
-               make_new_child($thisserver);
-	    }
-        }       
+    my $deadpid = wait;		# Wait for the next child to die.
+                                # See who died and start new one
+                                # or a signal (e.g. USR1 for restart).
+                                # if a signal, the wait will fail
+                                # This is ordinarily detected by
+                                # checking for the existence of the
+                                # pid index inthe children hash since
+                                # the return value from a failed wait is -1
+                                # which is an impossible PID.
+    &status("Woke up");
+    my $skipping='';
+
+    if(exists($children{$deadpid})) {
+
+	$thisserver = $children{$deadpid}; # Look name of dead guy's peer.
+
+	delete($children{$deadpid}); # Get rid of dead hash entry.
+
+	if($childatt{$thisserver} < $childmaxattempts) {
+	    $childatt{$thisserver}++;
+	    &logthis(
+	       "<font color=yellow>INFO: Trying to reconnect for $thisserver "
+            ."($childatt{$thisserver} of $childmaxattempts attempts)</font>"); 
+	    make_new_child($thisserver);
+	
+	}
+	else {
+	    $skipping .= $thisserver.' ';
+	}
+	if($skipping) {
+	    &logthis("<font color=blue>WARNING: Skipped $skipping</font>");
+  
+	}
     }
+
 }
 
 
+
 sub make_new_child {
    
-    my $conserver=shift;
+    $newserver=shift;
     my $pid;
     my $sigset;
-    &logthis("Attempting to start child for server $conserver");
+    &logthis("Attempting to start child for server $newserver");
     # block signal for fork
     $sigset = POSIX::SigSet->new(SIGINT);
     sigprocmask(SIG_BLOCK, $sigset)
@@ -259,13 +224,15 @@ sub make_new_child {
         # Parent records the child's birth and returns.
         sigprocmask(SIG_UNBLOCK, $sigset)
             or die "Can't unblock SIGINT for fork: $!\n";
-        $children{$pid} = $conserver;
-        $childpid{$conserver} = $pid;
+        $children{$pid} = $newserver;
+        $childpid{$newserver} = $pid;
         return;
     } else {
+        $conserver=$newserver;
         # Child can *not* return from this subroutine.
         $SIG{INT} = 'DEFAULT';      # make SIGINT kill us as it did before
-    
+        $SIG{USR1}= \&logstatus;
+   
         # unblock signals
         sigprocmask(SIG_UNBLOCK, $sigset)
             or die "Can't unblock SIGINT for fork: $!\n";
@@ -275,61 +242,13 @@ sub make_new_child {
 $port = "$perlvar{'lonSockDir'}/$conserver";
 
 unlink($port);
-# ---------------------------------------------------- Client to network server
-unless (
-  $remotesock = IO::Socket::INET->new(PeerAddr => $hostip{$conserver},
-                                      PeerPort => $perlvar{'londPort'},
-                                      Proto    => "tcp",
-                                      Type     => SOCK_STREAM)
-   ) { 
-       my $st=120+int(rand(240));
-       &logthis(
-"<font color=blue>WARNING: Couldn't connect $conserver ($st secs): $@</font>");
-       sleep($st);
-       exit; 
-     };
-# --------------------------------------- Send a ping to make other end do USR1
-print $remotesock "init\n";
-$answer=<$remotesock>;
-print $remotesock "$answer";
-$answer=<$remotesock>;
-chomp($answer);
-&logthis("Init reply for $conserver: >$answer<");
-if ($answer ne 'ok') {
-       my $st=120+int(rand(240));
-       &logthis(
-"<font color=blue>WARNING: Init failed $conserver ($st secs)</font>");
-       sleep($st);
-       exit; 
-}
-sleep 5;
-print $remotesock "pong\n";
-$answer=<$remotesock>;
-chomp($answer);
-&logthis("Pong reply for $conserver: >$answer<");
-# ----------------------------------------------------------- Initialize cipher
 
-print $remotesock "ekey\n";
-my $buildkey=<$remotesock>;
-my $key=$conserver.$perlvar{'lonHostID'};
-$key=~tr/a-z/A-Z/;
-$key=~tr/G-P/0-9/;
-$key=~tr/Q-Z/0-9/;
-$key=$key.$buildkey.$key.$buildkey.$key.$buildkey;
-$key=substr($key,0,32);
-my $cipherkey=pack("H32",$key);
-if ($cipher=new IDEA $cipherkey) {
-   &logthis("Secure connection initialized: $conserver");
-} else {
-   my $st=120+int(rand(240));
-   &logthis(
-     "<font color=blue>WARNING: ".
-     "Could not establish secure connection, $conserver ($st secs)!</font>");
-   sleep($st);
-   exit;
-}
+# -------------------------------------------------------------- Open other end
 
+&openremote($conserver);
+	&logthis("<font color=green> Connection to $conserver open </font>");
 # ----------------------------------------- We're online, send delayed messages
+    &status("Checking for delayed messages");
 
     my @allbuffered;
     my $path="$perlvar{'lonSockDir'}/delayed";
@@ -337,9 +256,10 @@ if ($cipher=new IDEA $cipherkey) {
     @allbuffered=grep /\.$conserver$/, readdir DIRHANDLE;
     closedir(DIRHANDLE);
     my $dfname;
-    map {
+    foreach (sort @allbuffered) {
+        &status("Sending delayed: $_");
         $dfname="$path/$_";
-        &logthis($dfname);
+        if($DEBUG) { &logthis('Sending '.$dfname); }
         my $wcmd;
         {
          my $dfh=IO::File->new($dfname);
@@ -360,18 +280,19 @@ if ($cipher=new IDEA $cipherkey) {
             }
             $cmd="enc:$cmdlength:$encrequest\n";
         }
-
-        print $remotesock "$cmd\n";
-        $answer=<$remotesock>;
+	$answer = londtransaction($remotesock, $cmd, 60);
 	chomp($answer);
-        if ($answer ne '') {
+
+        if (($answer ne '') && ($@!~/timeout/)) {
 	    unlink("$dfname");
-            &logthis("Delayed $cmd to $conserver: >$answer<");
+            &logthis("Delayed $cmd: >$answer<");
             &logperm("S:$conserver:$bcmd");
         }        
-    } @allbuffered;
+    }
+	if($DEBUG) { &logthis("<font color=green> Delayed transactions sent"); }
 
 # ------------------------------------------------------- Listen to UNIX socket
+&status("Opening socket");
 unless (
   $server = IO::Socket::UNIX->new(Local  => $port,
                                   Type   => SOCK_STREAM,
@@ -380,11 +301,11 @@ unless (
        my $st=120+int(rand(240));
        &logthis(
          "<font color=blue>WARNING: ".
-         "Can't make server socket $conserver ($st secs): $@</font>");
+         "Can't make server socket ($st secs):  .. exiting</font>");
        sleep($st);
        exit; 
      };
-
+   
 # -----------------------------------------------------------------------------
 
 &logthis("<font color=green>$conserver online</font>");
@@ -394,110 +315,314 @@ unless (
 %inbuffer  = ();
 %outbuffer = ();
 %ready     = ();
+%servers   = ();	# To be compatible with make filevector.  indexed by
+			# File ids, values are sockets.
+			# note that the accept socket is omitted.
 
 tie %ready, 'Tie::RefHash';
 
-nonblock($server);
-$select = IO::Select->new($server);
+# nonblock($server);
+# $select = IO::Select->new($server);
 
 # Main loop: check reads/accepts, check writes, check ready to process
+
+status("Main loop $conserver");
 while (1) {
     my $client;
     my $rv;
     my $data;
 
-    # check for new information on the connections we have
+    my $infdset;		# bit vec of fd's to select on input.
 
-    # anything to read or accept?
-    foreach $client ($select->can_read(0.1)) {
+    my $outfdset;		# Bit vec of fd's to select on output.
 
-        if ($client == $server) {
-            # accept a new connection
 
-            $client = $server->accept();
-            $select->add($client);
-            nonblock($client);
-        } else {
-            # read data
-            $data = '';
-            $rv   = $client->recv($data, POSIX::BUFSIZ, 0);
-
-            unless (defined($rv) && length $data) {
-                # This would be the end of file, so close the client
-                delete $inbuffer{$client};
-                delete $outbuffer{$client};
-                delete $ready{$client};
-
-                $select->remove($client);
-                close $client;
-                next;
-            }
+    $infdset = MakeFileVector(\%servers);
+    $outfdset= MakeFileVector(\%outbuffer);
+    vec($infdset, $server->fileno, 1) = 1;
+    if($DEBUG) {
+	&logthis("Adding ".$server->fileno.
+		 " to input select vector (listner)".
+		 unpack("b*",$infdset)."\n");
+    }
+    DoSelect(\$infdset, \$outfdset); # Wait for input.
+    if($DEBUG) {
+	&logthis("Doselect completed!");
+	&logthis("ins = ".unpack("b*",$infdset)."\n");
+	&logthis("outs= ".unpack("b*",$outfdset)."\n");
+		 
+    }
 
-            $inbuffer{$client} .= $data;
+    # Checkfor new connections:
+    if (vec($infdset, $server->fileno, 1)) {
+	if($DEBUG) {
+	    &logthis("New connection established");
+	}
+	# accept a new connection
+	&status("Accept new connection: $conserver");
+	$client = $server->accept();
+	if($DEBUG) {
+	    &logthis("New client fd = ".$client->fileno."\n");
+	}
+	$servers{$client->fileno} = $client;
+	nonblock($client);
+	$client->sockopt(SO_KEEPALIVE, 1);# Enable monitoring of
+	                                  # connection liveness.
+    }
+    HandleInput($infdset, \%servers, \%inbuffer, \%outbuffer, \%ready);
+    HandleOutput($outfdset, \%servers, \%outbuffer, \%inbuffer,
+		 \%ready);
+# -------------------------------------------------------- Wow, connection lost
 
-            # test whether the data in the buffer or the data we
-            # just read means there is a complete request waiting
-            # to be fulfilled.  If there is, set $ready{$client}
-            # to the requests waiting to be fulfilled.
-            while ($inbuffer{$client} =~ s/(.*\n)//) {
-                push( @{$ready{$client}}, $1 );
-            }
-        }
+}
+   
     }
+}
 
-    # Any complete requests to process?
-    foreach $client (keys %ready) {
-        handle($client);
+# ------------------------------------------------------- End of make_new_child
+
+
+#
+#  Make a vector of file descriptors to wait for in a select.
+#  parameters:
+#     \%fdhash  -reference to a hash which has IO::Socket's as indices.  
+#                We only care about the indices, not the values.
+#  A select vector is created from all indices of the hash.
+
+sub MakeFileVector
+{
+    my $fdhash = shift;
+    my $selvar = "";
+
+    foreach $socket (keys %$fdhash) {
+	if($DEBUG) {
+	    &logthis("Adding  ".$socket.
+		     "to select vector. (client)\n");
+	}
+	vec($selvar, $socket, 1) = 1;
     }
+    return $selvar;
+}
 
-    # Buffers to flush?
-    foreach $client ($select->can_write(1)) {
-        # Skip this client if we have nothing to say
-        next unless exists $outbuffer{$client};
-
-        $rv = $client->send($outbuffer{$client}, 0);
-        unless (defined $rv) {
-            # Whine, but move on.
-            &logthis("I was told I could write, but I can't.\n");
-            next;
-        }
-        $errno=$!;
-        if (($rv == length $outbuffer{$client}) ||
-            ($errno == POSIX::EWOULDBLOCK) || ($errno == 0)) {
-            substr($outbuffer{$client}, 0, $rv) = '';
-            delete $outbuffer{$client} unless length $outbuffer{$client};
-        } else {
-            # Couldn't write all the data, and it wasn't because
-            # it would have blocked.  Shutdown and move on.
 
-	    &logthis("Dropping data with ".$errno.": ".
-                     length($outbuffer{$client}).", $rv");
+#
+#  HandleOutput:
+#    Processes output on a buffered set of file descriptors which are
+#    ready to be read.
+#  Parameters:
+#    $selvector - Vector of file descriptors which are writable.
+#    \%sockets  - Vector of socket references indexed by socket.
+#    \%buffers  - Reference to a hash containing output buffers.
+#                 Hashes are indexed by sockets.  The file descriptors of some
+#                 of those sockets will be present in $selvector.
+#                 For each one of those, we will attempt to write the output
+#                 buffer to the socket.  Note that we will assume that
+#                 the sockets are being run in non blocking mode.
+#   \%inbufs    - Reference to hash containing input buffers.
+#   \%readys    - Reference to hash containing flags for items with complete
+#                 requests.
+#
+sub HandleOutput
+{
+    my $selvector = shift;
+    my $sockets   = shift;
+    my $buffers   = shift;
+    my $inbufs    = shift;
+    my $readys    = shift;
+    my $sock;
 
-            delete $inbuffer{$client};
-            delete $outbuffer{$client};
-            delete $ready{$client};
-
-            $select->remove($client);
-            close($client);
-            next;
-        }
+    if($DEBUG) {
+	&logthis("HandleOutput entered\n");
     }
+
+    foreach $sock (keys %$sockets) {
+	my $socket = $sockets->{$sock};
+	if(vec($selvector, $sock, 1)) { # $socket is writable.
+	    if($DEBUG) {
+		&logthis("Sending $buffers->{$sock} \n");
+	    }
+	    my $rv = $socket->send($buffers->{$sock}, 0);
+	    $errno = $!;
+	    unless ($buffers->{$sock} eq "con_lost\n") {
+		unless (defined $rv) { # Write failed... could be EINTR
+		    unless ($errno == POSIX::EINTR) {
+			&logthis("Write failed on writable socket");
+		    }		# EINTR is not an error .. just retry.
+		    next;
+		}
+		if( ($rv == length $buffers->{$sock})    ||
+		    ($errno == POSIX::EWOULDBLOCK)       ||
+		    ($errno == POSIX::EAGAIN)            || # same as above.
+		    ($errno == POSIX::EINTR)             || # signal during IO
+		    ($errno == 0)) {
+		    substr($buffers->{$sock}, 0, $rv)=""; # delete written part
+		    delete $buffers->{$sock} unless length $buffers->{$sock};
+		} else {
+		    # For some reason the write failed with an error code
+		    # we didn't look for.  Shutdown the socket.
+		    &logthis("Unable to write data with ".$errno.": ".
+			     "Dropping data: ".length($buffers->{$sock}).
+			     ", $rv");
+		    #
+		    # kill off the buffers in the hash:
+
+		    delete $buffers->{$sock};
+		    delete $inbufs->{$sock};
+		    delete $readys->{$sock};
+
+		    close($socket); # Close the client socket.
+		    next;
+		}
+	    } else {		# Kludgy way to mark lond connection lost.
+		&logthis(
+		 "<font color=red>CRITICAL lond connection lost</font>");
+		status("Connection lost");
+		$remotesock->shutdown(2);
+		&logthis("Attempting to open a new connection");
+		&openremote($conserver);
+	    }
+		   
+	}
+    }
+
 }
+#
+#   HandleInput - Deals with input on client sockets.
+#                 Each socket has an associated input buffer.
+#                 For each readable socket, the currently available
+#                 data is appended to this buffer.
+#                 If necessary, the buffer is created.
+#                 On various failures, we may shutdown the client.
+#  Parameters:
+#     $selvec   - Vector of readable sockets.
+#     \%sockets - Refers to the  Hash of sockets indexed by sockets.  
+#                 Each of these may or may not have it's fd bit set 
+#                 in the $selvec.
+#     \%ibufs   - Refers to the hash of input buffers indexed by socket.
+#     \%obufs   - Hash of output buffers indexed by socket. 
+#     \%ready   - Hash of ready flags indicating the existence of a completed
+#                 Request.
+sub HandleInput 
+{
+
+    # Marshall the parameters.   Note that the hashes are actually
+    # references not values.
+
+    my $selvec  = shift;
+    my $sockets = shift;
+    my $ibufs   = shift;
+    my $obufs   = shift;
+    my $ready   = shift;
+    my $sock;
+
+    if($DEBUG) {
+	&logthis("Entered HandleInput\n");
+    }
+    foreach $sock (keys %$sockets) {
+	my $socket = $sockets->{$sock};
+	if(vec($selvec, $sock, 1)) { # Socket which is readable.
+
+	    #  Attempt to read the data and do error management.
+	    my $data = '';
+	    my $rv = $socket->recv($data, POSIX::BUFSIZ, 0);
+	    if($DEBUG) {
+		&logthis("Received $data from socket");
+	    }
+	    unless (defined($rv) && length $data) {
+
+		# Read an end of file.. this is a disconnect from the peer.
+
+		delete $sockets->{$sock};
+		delete $ibufs->{$sock};
+		delete $obufs->{$sock};
+		delete $ready->{$sock};
+
+		status("Idle");
+		close $socket;
+		next;
+	    }
+	    #  Append the read data to the input buffer. If the buffer
+	    # now contains a \n the request is complete and we can 
+	    # mark this in the $ready hash (one request for each \n.)
+
+	    $ibufs->{$sock} .= $data;
+	    while($ibufs->{$sock} =~ s/(.*\n)//) {
+		push(@{$ready->{$sock}}, $1);
+	    }
+	    
+	}
+    }
+    #  Now handle any requests which are ready:
+
+    foreach $client (keys %ready) {
+	handle($client);
+    }
 }
 
-# ------------------------------------------------------- End of make_new_child
+# DoSelect:  does a select with no timeout.  On signal (errno == EINTR), 
+#            the select is retried until there are items in the returned
+#            vectors.  
+#
+# Parameters:
+#   \$readvec   - Reference to a vector of file descriptors to 
+#                 check for readability.
+#   \$writevec  - Reference to a vector of file descriptors to check for
+#                 writability.
+#  On exit, the referents are modified with vectors indicating which 
+#  file handles are readable/writable.
+#
+sub DoSelect {
+    my $readvec = shift;
+    my $writevec= shift;
+    my $outs;
+    my $ins;
+
+    while (1) {
+	my $nfds = select( $ins = $$readvec, $outs = $$writevec, undef, undef);
+	if($nfds) {
+	    if($DEBUG) {
+		&logthis("select exited with ".$nfds." fds\n");
+		&logthis("ins = ".unpack("b*",$ins).
+			 " readvec = ".unpack("b*",$$readvec)."\n");
+		&logthis("outs = ".unpack("b*",$outs).
+			 " writevec = ".unpack("b*",$$writevec)."\n");
+	    }
+	    $$readvec  = $ins;
+	    $$writevec = $outs;
+	    return;
+	} else {
+	    if($DEBUG) {
+		&logthis("Select exited with no bits set in mask\n");
+	    }
+	    die "Select failed" unless $! == EINTR;
+	}
+    }
+}
 
 # handle($socket) deals with all pending requests for $client
+#
 sub handle {
     # requests are in $ready{$client}
     # send output to $outbuffer{$client}
     my $client = shift;
     my $request;
-
     foreach $request (@{$ready{$client}}) {
 # ============================================================= Process request
         # $request is the text of the request
         # put text of reply into $outbuffer{$client}
+# ------------------------------------------------------------ Is this the end?
+	chomp($request);
+	if($DEBUG) {
+     &logthis("<font color=green> Request $request processing starts</font>");
+        }
+        if ($request eq "close_connection_exit\n") {
+	    &status("Request close connection");
+           &logthis(
+     "<font color=red>CRITICAL: Request Close Connection ... exiting</font>");
+           $remotesock->shutdown(2);
+           $server->close();
+           exit;
+        }
 # -----------------------------------------------------------------------------
         if ($request =~ /^encrypt\:/) {
 	    my $cmd=$request;
@@ -510,10 +635,21 @@ sub handle {
                 $encrequest.=
                     unpack("H16",$cipher->encrypt(substr($cmd,$encidx,8)));
             }
-            $request="enc:$cmdlength:$encrequest\n";
+            $request="enc:$cmdlength:$encrequest";
         }
-        print $remotesock "$request";
-        $answer=<$remotesock>;
+# --------------------------------------------------------------- Main exchange
+	$answer = londtransaction($remotesock, $request, 300);
+
+	if($DEBUG) { 
+	    &logthis("<font color=green> Request data exchange complete");
+	}
+	if ($@=~/timeout/) { 
+	    $answer='';
+	    &logthis(
+		     "<font color=red>CRITICAL: Timeout: $request</font>");
+	}  
+
+
         if ($answer) {
 	   if ($answer =~ /^enc/) {
                my ($cmd,$cmdlength,$encinput)=split(/:/,$answer);
@@ -527,18 +663,27 @@ sub handle {
 	      $answer=substr($answer,0,$cmdlength);
 	      $answer.="\n";
 	   }
+	   if($DEBUG) {
+	       &logthis("sending $answer to client\n");
+	   }
            $outbuffer{$client} .= $answer;
         } else {
            $outbuffer{$client} .= "con_lost\n";
         }
 
+     &status("Completed: $request");
+	if($DEBUG) {
+	    &logthis("<font color=green> Request processing complete</font>");
+	}
 # ===================================================== Done processing request
     }
     delete $ready{$client};
 # -------------------------------------------------------------- End non-forker
+    if($DEBUG) {
+	&logthis("<font color=green> requests for child handled</font>");
+    }
 }
 # ---------------------------------------------------------- End make_new_child
-}
 
 # nonblock($socket) puts socket into nonblocking mode
 sub nonblock {
@@ -552,3 +697,490 @@ sub nonblock {
             or die "Can't make socket nonblocking: $!\n";
 }
 
+
+sub openremote {
+# ---------------------------------------------------- Client to network server
+
+    my $conserver=shift;
+
+    &status("Opening TCP $conserver");
+    my $st=120+int(rand(240)); # Sleep before opening:
+
+    unless (
+	    $remotesock = IO::Socket::INET->new(PeerAddr => $hostip{$conserver},
+						PeerPort => $perlvar{'londPort'},
+						Proto    => "tcp",
+						Type     => SOCK_STREAM)
+	   ) {
+
+	&logthis(
+		 "<font color=blue>WARNING: Couldn't connect to $conserver ($st secs): </font>");
+	sleep($st);
+	exit;
+    };
+# ----------------------------------------------------------------- Init dialog
+
+    &logthis("<font color=green>INFO Connected to $conserver, initing</font>");
+    &status("Init dialogue: $conserver");
+
+    $answer = londtransaction($remotesock, "init", 60);
+    chomp($answer);
+    $answer = londtransaction($remotesock, $answer, 60);
+    chomp($answer);
+
+    if ($@=~/timeout/) {
+	&logthis("Timed out during init.. exiting");
+	exit;
+    }
+
+    if ($answer ne 'ok') {
+	&logthis("Init reply: >$answer<");
+	my $st=120+int(rand(240));
+	&logthis("<font color=blue>WARNING: Init failed ($st secs)</font>");
+	sleep($st);
+	exit;
+    }
+
+    $answer = londtransaction($remotesock,"sethost:$conserver",60);
+    chomp($answer);
+    if ( $answer ne 'ok') {
+	&logthis('<font color="blue">WARNING: unable to specify remote host'.
+		 $answer.'</font>');
+    }
+
+    $answer = londtransaction($remotesock,"version:$VERSION",60);
+    chomp($answer);
+    if ($answer =~ /^version:/) {
+	$remoteVERSION=(split(/:/,$answer))[1];
+    } else {
+	&logthis('<font color="blue">WARNING: request remote version failed :'.
+		 $answer.': my version is :'.$VERSION.':</font>');
+    }
+
+    sleep 5;
+    &status("Ponging $conserver");
+    print $remotesock "pong\n";
+    $answer=<$remotesock>;
+    chomp($answer);
+    if ($answer!~/^$conserver/) {
+	&logthis("Pong reply: >$answer<");
+    }
+# ----------------------------------------------------------- Initialize cipher
+
+    &status("Initialize cipher");
+    print $remotesock "ekey\n";
+    my $buildkey=<$remotesock>;
+    my $key=$conserver.$perlvar{'lonHostID'};
+    $key=~tr/a-z/A-Z/;
+    $key=~tr/G-P/0-9/;
+    $key=~tr/Q-Z/0-9/;
+    $key=$key.$buildkey.$key.$buildkey.$key.$buildkey;
+    $key=substr($key,0,32);
+    my $cipherkey=pack("H32",$key);
+    if ($cipher=new IDEA $cipherkey) {
+	&logthis("Secure connection initialized");
+    } else {
+	my $st=120+int(rand(240));
+	&logthis("<font color=blue>WARNING: ".
+		 "Could not establish secure connection ($st secs)!</font>");
+	sleep($st);
+	exit;
+    }
+    &logthis("<font color=green> Remote open success </font>");
+}
+
+
+
+# grabs exception and records it to log before exiting
+sub catchexception {
+    my ($signal)=@_;
+    $SIG{QUIT}='DEFAULT';
+    $SIG{__DIE__}='DEFAULT';
+    chomp($signal);
+    &logthis("<font color=red>CRITICAL: "
+     ."ABNORMAL EXIT. Child $$ for server [$wasserver] died through "
+     ."\"$signal\" with parameter </font>");
+    die("Signal abend");
+}
+
+# -------------------------------------- Routines to see if other box available
+
+#sub online {
+#    my $host=shift;
+#    &status("Pinging ".$host);
+#    my $p=Net::Ping->new("tcp",20);
+#    my $online=$p->ping("$host");
+#    $p->close();
+#    undef ($p);
+#    return $online;
+#}
+
+sub connected {
+    my ($local,$remote)=@_;
+    &status("Checking connection $local to $remote");
+    $local=~s/\W//g;
+    $remote=~s/\W//g;
+
+    unless ($hostname{$local}) { return 'local_unknown'; }
+    unless ($hostname{$remote}) { return 'remote_unknown'; }
+
+    #unless (&online($hostname{$local})) { return 'local_offline'; }
+
+    my $ua=new LWP::UserAgent;
+    
+    my $request=new HTTP::Request('GET',
+      "http://".$hostname{$local}.'/cgi-bin/ping.pl?'.$remote);
+
+    my $response=$ua->request($request);
+
+    unless ($response->is_success) { return 'local_error'; }
+
+    my $reply=$response->content;
+    $reply=(split("\n",$reply))[0];
+    $reply=~s/\W//g;
+    if ($reply ne $remote) { return $reply; }
+    return 'ok';
+}
+
+
+
+sub hangup {
+    foreach (keys %children) {
+        $wasserver=$children{$_};
+        &status("Closing $wasserver");
+        &logthis('Closing '.$wasserver.': '.&subreply('exit',$wasserver));
+        &status("Kill PID $_ for $wasserver");
+	kill ('INT',$_);
+    }
+}
+
+sub HUNTSMAN {                      # signal handler for SIGINT
+    local($SIG{CHLD}) = 'IGNORE';   # we're going to kill our children
+    &hangup();
+    my $execdir=$perlvar{'lonDaemons'};
+    unlink("$execdir/logs/lonc.pid");
+    &logthis("<font color=red>CRITICAL: Shutting down</font>");
+    exit;                           # clean up with dignity
+}
+
+sub HUPSMAN {                      # signal handler for SIGHUP
+    local($SIG{CHLD}) = 'IGNORE';  # we're going to kill our children
+    &hangup();
+    &logthis("<font color=red>CRITICAL: Restarting</font>");
+    unlink("$execdir/logs/lonc.pid");
+    my $execdir=$perlvar{'lonDaemons'};
+    exec("$execdir/lonc");         # here we go again
+}
+
+sub checkchildren {
+    &initnewstatus();
+    &logstatus();
+    &logthis('Going to check on the children');
+    foreach (sort keys %children) {
+	sleep 1;
+        unless (kill 'USR1' => $_) {
+	    &logthis ('<font color=red>CRITICAL: Child '.$_.' is dead</font>');
+            &logstatus($$.' is dead');
+        } 
+    }
+}
+
+sub USRMAN {
+    &logthis("USR1: Trying to establish connections again");
+    #
+    #  It is really important not to just clear the childatt hash or we will
+    #  lose all memory of the children.  What we really want to do is this:
+    #  For each index where childatt is >= $childmaxattempts
+    #  Zero the associated counter and do a make_child for the host.
+    #  Regardles, the childatt entry is zeroed:
+    my $host;
+    foreach $host (keys %childatt) {
+	if ($childatt{$host} >= $childmaxattempts) {
+	    $childatt{$host} = 0;
+	    &logthis("<font color=green>INFO: Restarting child for server: "
+		     .$host."</font>\n");
+	    make_new_child($host);
+	}
+	else {
+	    $childatt{$host} = 0;
+	}
+    }
+    &checkchildren();		# See if any children are still dead...
+}
+
+# -------------------------------------------------- Non-critical communication
+sub subreply { 
+ my ($cmd,$server)=@_;
+ my $answer='';
+ if ($server ne $perlvar{'lonHostID'}) { 
+    my $peerfile="$perlvar{'lonSockDir'}/$server";
+    my $sclient=IO::Socket::UNIX->new(Peer    =>"$peerfile",
+                                      Type    => SOCK_STREAM,
+                                      Timeout => 10)
+       or return "con_lost";
+
+
+    $answer = londtransaction($sclient, $cmd, 10);
+
+    if ((!$answer) || ($@=~/timeout/)) { $answer="con_lost"; }
+    $SIG{ALRM}='DEFAULT';
+    $SIG{__DIE__}=\&catchexception;
+ } else { $answer='self_reply'; }
+ return $answer;
+}
+
+# --------------------------------------------------------------------- Logging
+
+sub logthis {
+    my $message=shift;
+    my $execdir=$perlvar{'lonDaemons'};
+    my $fh=IO::File->new(">>$execdir/logs/lonc.log");
+    my $now=time;
+    my $local=localtime($now);
+    $lastlog=$local.': '.$message;
+    print $fh "$local ($$) [$conserver] [$status]: $message\n";
+}
+
+#--------------------------------------  londtransaction:
+#  
+#  Performs a transaction with lond with timeout support.
+#    result = londtransaction(socket,request,timeout)
+#
+sub londtransaction {
+    my ($socket, $request, $tmo) = @_;
+
+    if($DEBUG) {
+	&logthis("londtransaction request: $request");
+    }
+
+    # Set the signal handlers: ALRM for timeout and disble the others.
+
+    $SIG{ALRM} = sub { die "timeout" };
+    $SIG{__DIE__} = 'DEFAULT';
+    
+    # Disable all but alarm so that only that can interupt the
+    # send /receive.
+    #
+    my $sigset = POSIX::SigSet->new(QUIT, USR1, HUP, INT, TERM);
+    my $priorsigs = POSIX::SigSet->new;
+    unless (defined sigprocmask(SIG_BLOCK, $sigset, $priorsigs)) {
+	&logthis("<font color=red> CRITICAL -- londtransaction ".
+		"failed to block signals </font>");
+	die "could not block signals in londtransaction";
+    }
+    $answer = '';
+    #
+    #  Send request to lond.
+    #
+    eval { 
+	alarm($tmo);
+	print $socket "$request\n";
+	alarm(0);
+    };
+    #  If request didn't timeout, try for the response.
+    #
+
+    if ($@!~/timeout/) {
+	eval {
+	    alarm($tmo);
+	    $answer = <$socket>;
+	    if($DEBUG) {
+		&logthis("Received $answer in londtransaction");
+	    }
+	    alarm(0);
+	};
+    } else {
+	&logthis("lonc - suiciding on send Timeout");
+	die("lonc - suiciding on send Timeout");
+    }
+    if ($@ =~ /timeout/) {
+	&logthis("lonc - suiciding on read Timeout");
+	die("lonc - suiciding on read Timeout");
+    }
+    #
+    # Restore the initial sigmask set.
+    #
+    unless (defined sigprocmask(SIG_UNBLOCK, $priorsigs)) {
+	&logthis("<font color=red> CRITICAL -- londtransaction ".
+		"failed to re-enable signal processing. </font>");
+	die "londtransaction failed to re-enable signals";
+    }
+    #
+    # go back to the prior handler set.
+    #
+    $SIG{ALRM} = 'DEFAULT';
+    $SIG{__DIE__} = \&cathcexception;
+
+    #    chomp $answer;
+    if ($DEBUG) {
+	&logthis("Returning $answer in londtransaction");
+    }
+    return $answer;
+
+}
+
+sub logperm {
+    my $message=shift;
+    my $execdir=$perlvar{'lonDaemons'};
+    my $now=time;
+    my $local=localtime($now);
+    my $fh=IO::File->new(">>$execdir/logs/lonnet.perm.log");
+    print $fh "$now:$message:$local\n";
+}
+# ------------------------------------------------------------------ Log status
+
+sub logstatus {
+    my $docdir=$perlvar{'lonDocRoot'};
+    my $fh=IO::File->new(">>$docdir/lon-status/loncstatus.txt");
+    print $fh $$."\t".$conserver."\t".$status."\t".$lastlog."\n";
+}
+
+sub initnewstatus {
+    my $docdir=$perlvar{'lonDocRoot'};
+    my $fh=IO::File->new(">$docdir/lon-status/loncstatus.txt");
+    my $now=time;
+    my $local=localtime($now);
+    print $fh "LONC status $local - parent $$\n\n";
+}
+
+# -------------------------------------------------------------- Status setting
+
+sub status {
+    my $what=shift;
+    my $now=time;
+    my $local=localtime($now);
+    $status=$local.': '.$what;
+    $0='lonc: '.$what.' '.$local;
+}
+
+
+
+# ----------------------------------- POD (plain old documentation, CPAN style)
+
+=head1 NAME
+
+lonc - LON TCP-MySQL-Server Daemon for handling database requests.
+
+=head1 SYNOPSIS
+
+Usage: B<lonc>
+
+Should only be run as user=www.  This is a command-line script which
+is invoked by B<loncron>.  There is no expectation that a typical user
+will manually start B<lonc> from the command-line.  (In other words,
+DO NOT START B<lonc> YOURSELF.)
+
+=head1 DESCRIPTION
+
+Provides persistent TCP connections to the other servers in the network
+through multiplexed domain sockets
+
+B<lonc> forks off children processes that correspond to the other servers
+in the network.  Management of these processes can be done at the
+parent process level or the child process level.
+
+  After forking off the children, B<lonc> the B<parent> 
+executes a main loop which simply waits for processes to exit.
+As a process exits, a new process managing a link to the same
+peer as the exiting process is created.  
+
+B<logs/lonc.log> is the location of log messages.
+
+The process management is now explained in terms of linux shell commands,
+subroutines internal to this code, and signal assignments:
+
+=over 4
+
+=item *
+
+PID is stored in B<logs/lonc.pid>
+
+This is the process id number of the parent B<lonc> process.
+
+=item *
+
+SIGTERM and SIGINT
+
+Parent signal assignment:
+ $SIG{INT}  = $SIG{TERM} = \&HUNTSMAN;
+
+Child signal assignment:
+ $SIG{INT}  = 'DEFAULT'; (and SIGTERM is DEFAULT also)
+(The child dies and a SIGALRM is sent to parent, awaking parent from slumber
+ to restart a new child.)
+
+Command-line invocations:
+ B<kill> B<-s> SIGTERM I<PID>
+ B<kill> B<-s> SIGINT I<PID>
+
+Subroutine B<HUNTSMAN>:
+ This is only invoked for the B<lonc> parent I<PID>.
+This kills all the children, and then the parent.
+The B<lonc.pid> file is cleared.
+
+=item *
+
+SIGHUP
+
+Current bug:
+ This signal can only be processed the first time
+on the parent process.  Subsequent SIGHUP signals
+have no effect.
+
+Parent signal assignment:
+ $SIG{HUP}  = \&HUPSMAN;
+
+Child signal assignment:
+ none (nothing happens)
+
+Command-line invocations:
+ B<kill> B<-s> SIGHUP I<PID>
+
+Subroutine B<HUPSMAN>:
+ This is only invoked for the B<lonc> parent I<PID>,
+This kills all the children, and then the parent.
+The B<lonc.pid> file is cleared.
+
+=item *
+
+SIGUSR1
+
+Parent signal assignment:
+ $SIG{USR1} = \&USRMAN;
+
+Child signal assignment:
+ $SIG{USR1}= \&logstatus;
+
+Command-line invocations:
+ B<kill> B<-s> SIGUSR1 I<PID>
+
+Subroutine B<USRMAN>:
+ When invoked for the B<lonc> parent I<PID>,
+SIGUSR1 is sent to all the children, and the status of
+each connection is logged.
+
+
+=back
+
+=head1 PREREQUISITES
+
+POSIX
+IO::Socket
+IO::Select
+IO::File
+Socket
+Fcntl
+Tie::RefHash
+Crypt::IDEA
+
+=head1 COREQUISITES
+
+=head1 OSNAMES
+
+linux
+
+=head1 SCRIPT CATEGORIES
+
+Server/Process
+
+=cut
<!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML 2.0//EN">
<html><head>
<title>500 Internal Server Error</title>
</head><body>
<h1>Internal Server Error</h1>
<p>The server encountered an internal error or
misconfiguration and was unable to complete
your request.</p>
<p>Please contact the server administrator at 
 root@localhost to inform them of the time this error occurred,
 and the actions you performed just before this error.</p>
<p>More information about this error may be available
in the server error log.</p>
</body></html>