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Diff for /loncom/Attic/lonc between versions 1.14 and 1.31

version 1.14, 2001/03/13 21:15:40 version 1.31, 2002/03/03 18:13:07
Line 5 Line 5
 # provides persistent TCP connections to the other servers in the network  # provides persistent TCP connections to the other servers in the network
 # through multiplexed domain sockets  # through multiplexed domain sockets
 #  #
   # $Id$
   #
   # 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  # PID in subdir logs/lonc.pid
 # kill kills  # kill kills
 # HUP restarts  # HUP restarts
Line 15 Line 39
 # 2/8,7/25 Gerd Kortemeyer  # 2/8,7/25 Gerd Kortemeyer
 # 12/05 Scott Harrison  # 12/05 Scott Harrison
 # 12/05 Gerd Kortemeyer  # 12/05 Gerd Kortemeyer
   # YEAR=2001
 # 01/10/01 Scott Harrison  # 01/10/01 Scott Harrison
 # 03/14/01 Gerd Kortemeyer  # 03/14/01,03/15,06/12,11/26,11/27,11/28 Gerd Kortemeyer
   # 12/20 Scott Harrison
   # YEAR=2002
   # 2/19/02,02/22/02,02/25/02 Gerd Kortemeyer
 #   # 
 # based on nonforker from Perl Cookbook  # based on nonforker from Perl Cookbook
 # - server who multiplexes without forking  # - server who multiplexes without forking
Line 29  use Socket; Line 57  use Socket;
 use Fcntl;  use Fcntl;
 use Tie::RefHash;  use Tie::RefHash;
 use Crypt::IDEA;  use Crypt::IDEA;
   use Net::Ping;
   use LWP::UserAgent();
   
 # grabs exception and records it to log before exiting  $status='';
 sub catchexception {  $lastlog='';
     my ($signal)=@_;  $conserver='SHELL';
     $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=10;  
   
 # -------------------------------- Set signal handlers to record abnormal exits  # -------------------------------- Set signal handlers to record abnormal exits
   
 $SIG{'QUIT'}=\&catchexception;  &status("Init exception handlers");
   $SIG{QUIT}=\&catchexception;
 $SIG{__DIE__}=\&catchexception;  $SIG{__DIE__}=\&catchexception;
   
 # ------------------------------------ Read httpd access.conf and get variables  # ------------------------------------ Read httpd access.conf and get variables
   &status("Read access.conf");
 open (CONFIG,"/etc/httpd/conf/access.conf") || die "Can't read access.conf";  open (CONFIG,"/etc/httpd/conf/access.conf") || die "Can't read access.conf";
   
 while ($configline=<CONFIG>) {  while ($configline=<CONFIG>) {
Line 62  while ($configline=<CONFIG>) { Line 84  while ($configline=<CONFIG>) {
 close(CONFIG);  close(CONFIG);
   
 # ----------------------------- Make sure this process is running from user=www  # ----------------------------- Make sure this process is running from user=www
   &status("Check user ID");
 my $wwwid=getpwnam('www');  my $wwwid=getpwnam('www');
 if ($wwwid!=$<) {  if ($wwwid!=$<) {
    $emailto="$perlvar{'lonAdmEMail'},$perlvar{'lonSysEMail'}";     $emailto="$perlvar{'lonAdmEMail'},$perlvar{'lonSysEMail'}";
Line 89  open (CONFIG,"$perlvar{'lonTabDir'}/host Line 112  open (CONFIG,"$perlvar{'lonTabDir'}/host
 while ($configline=<CONFIG>) {  while ($configline=<CONFIG>) {
     my ($id,$domain,$role,$name,$ip)=split(/:/,$configline);      my ($id,$domain,$role,$name,$ip)=split(/:/,$configline);
     chomp($ip);      chomp($ip);
     $hostip{$id}=$ip;      if ($ip) {
        $hostip{$id}=$ip;
        $hostname{$id}=$name;
       }
 }  }
   
 close(CONFIG);  close(CONFIG);
   
 # -------------------------------------------------------- Routines for forking  # -------------------------------------------------------- Routines for forking
Line 102  close(CONFIG); Line 129  close(CONFIG);
 %childatt               = ();       # number of attempts to start server  %childatt               = ();       # number of attempts to start server
                                     # for ID                                      # for ID
   
 sub REAPER {                        # takes care of dead children  $childmaxattempts=5;
     $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  
     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($SIG{CHLD}) = 'IGNORE';  # we're going to kill our children  
     kill 'INT' => keys %children;  
     &logthis("<font color=red>CRITICAL: Restarting</font>");  
     unlink("$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";  
 }  
   
 # ---------------------------------------------------- Fork once and dissociate  # ---------------------------------------------------- Fork once and dissociate
   &status("Fork and dissociate");
 $fpid=fork;  $fpid=fork;
 exit if $fpid;  exit if $fpid;
 die "Couldn't fork: $!" unless defined ($fpid);  die "Couldn't fork: $!" unless defined ($fpid);
   
 POSIX::setsid() or die "Can't start new session: $!";  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'};  $execdir=$perlvar{'lonDaemons'};
 open (PIDSAVE,">$execdir/logs/lonc.pid");  open (PIDSAVE,">$execdir/logs/lonc.pid");
 print PIDSAVE "$$\n";  print PIDSAVE "$$\n";
Line 204  $SIG{HUP}=$SIG{USR1}='IGNORE'; Line 155  $SIG{HUP}=$SIG{USR1}='IGNORE';
           
 # Fork off our children, one for every server  # Fork off our children, one for every server
   
   &status("Forking ...");
   
 foreach $thisserver (keys %hostip) {  foreach $thisserver (keys %hostip) {
     make_new_child($thisserver);      if (&online($hostname{$thisserver})) {
          make_new_child($thisserver);
       }
 }  }
   
 &logthis("Done starting initial servers");  &logthis("Done starting initial servers");
Line 218  $SIG{USR1} = \&USRMAN; Line 173  $SIG{USR1} = \&USRMAN;
   
 # And maintain the population.  # And maintain the population.
 while (1) {  while (1) {
       &status("Sleeping");
     sleep;                          # wait for a signal (i.e., child's death)      sleep;                          # wait for a signal (i.e., child's death)
                                     # See who died and start new one                                      # See who died and start new one
       &status("Woke up");
       my $skipping='';
     foreach $thisserver (keys %hostip) {      foreach $thisserver (keys %hostip) {
         if (!$childpid{$thisserver}) {          if (!$childpid{$thisserver}) {
     if ($childatt{$thisserver}<=$childmaxattempts) {      if (($childatt{$thisserver}<$childmaxattempts) &&
                   (&online($hostname{$thisserver}))) {
        $childatt{$thisserver}++;         $childatt{$thisserver}++;
                &logthis(                 &logthis(
    "<font color=yellow>INFO: Trying to reconnect for $thisserver "     "<font color=yellow>INFO: Trying to reconnect for $thisserver "
   ."($childatt{$thisserver} of $childmaxattempts attempts)</font>");     ."($childatt{$thisserver} of $childmaxattempts attempts)</font>"); 
                make_new_child($thisserver);                 make_new_child($thisserver);
     }     } else {
                  $skipping.=$thisserver.' ';
              } 
                  
         }                 }       
     }      }
       if ($skipping) { 
          &logthis("<font color=blue>WARNING: Skipped $skipping</font>");
       }
 }  }
   
   
 sub make_new_child {  sub make_new_child {
         
     my $conserver=shift;      $newserver=shift;
     my $pid;      my $pid;
     my $sigset;      my $sigset;
     &logthis("Attempting to start child for server $conserver");      &logthis("Attempting to start child for server $newserver");
     # block signal for fork      # block signal for fork
     $sigset = POSIX::SigSet->new(SIGINT);      $sigset = POSIX::SigSet->new(SIGINT);
     sigprocmask(SIG_BLOCK, $sigset)      sigprocmask(SIG_BLOCK, $sigset)
Line 251  sub make_new_child { Line 216  sub make_new_child {
         # Parent records the child's birth and returns.          # Parent records the child's birth and returns.
         sigprocmask(SIG_UNBLOCK, $sigset)          sigprocmask(SIG_UNBLOCK, $sigset)
             or die "Can't unblock SIGINT for fork: $!\n";              or die "Can't unblock SIGINT for fork: $!\n";
         $children{$pid} = $conserver;          $children{$pid} = $newserver;
         $childpid{$conserver} = $pid;          $childpid{$conserver} = $pid;
         return;          return;
     } else {      } else {
           $conserver=$newserver;
         # Child can *not* return from this subroutine.          # Child can *not* return from this subroutine.
         $SIG{INT} = 'DEFAULT';      # make SIGINT kill us as it did before          $SIG{INT} = 'DEFAULT';      # make SIGINT kill us as it did before
               $SIG{USR1}= \&logstatus;
      
         # unblock signals          # unblock signals
         sigprocmask(SIG_UNBLOCK, $sigset)          sigprocmask(SIG_UNBLOCK, $sigset)
             or die "Can't unblock SIGINT for fork: $!\n";              or die "Can't unblock SIGINT for fork: $!\n";
Line 267  sub make_new_child { Line 234  sub make_new_child {
 $port = "$perlvar{'lonSockDir'}/$conserver";  $port = "$perlvar{'lonSockDir'}/$conserver";
   
 unlink($port);  unlink($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<");  
 sleep 5;  
 print $remotesock "pong\n";  
 $answer=<$remotesock>;  
 chomp($answer);  
 &logthis("Pong reply for $conserver: >$answer<");  
 # ----------------------------------------------------------- Initialize cipher  
   
 print $remotesock "ekey\n";  # -------------------------------------------------------------- Open other end
 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;  
 }  
   
 # ----------------------------------------- We're online, send delayed messages  &openremote($conserver);
   
   # ----------------------------------------- We're online, send delayed messages
       &status("Checking for delayed messages");
     my @allbuffered;      my @allbuffered;
     my $path="$perlvar{'lonSockDir'}/delayed";      my $path="$perlvar{'lonSockDir'}/delayed";
     opendir(DIRHANDLE,$path);      opendir(DIRHANDLE,$path);
     @allbuffered=grep /\.$conserver$/, readdir DIRHANDLE;      @allbuffered=grep /\.$conserver$/, readdir DIRHANDLE;
     closedir(DIRHANDLE);      closedir(DIRHANDLE);
     my $dfname;      my $dfname;
     map {      foreach (@allbuffered) {
           &status("Sending delayed: $_");
         $dfname="$path/$_";          $dfname="$path/$_";
         &logthis($dfname);          &logthis('Sending '.$dfname);
         my $wcmd;          my $wcmd;
         {          {
          my $dfh=IO::File->new($dfname);           my $dfh=IO::File->new($dfname);
Line 345  if ($cipher=new IDEA $cipherkey) { Line 271  if ($cipher=new IDEA $cipherkey) {
             }              }
             $cmd="enc:$cmdlength:$encrequest\n";              $cmd="enc:$cmdlength:$encrequest\n";
         }          }
       $SIG{ALRM}=sub { die "timeout" };
       $SIG{__DIE__}='DEFAULT';
       eval {
           alarm(60);
         print $remotesock "$cmd\n";          print $remotesock "$cmd\n";
         $answer=<$remotesock>;          $answer=<$remotesock>;
  chomp($answer);   chomp($answer);
         if ($answer ne '') {          alarm(0);
       };
       $SIG{ALRM}='DEFAULT';
       $SIG{__DIE__}=\&catchexception;
   
           if (($answer ne '') && ($@!~/timeout/)) {
     unlink("$dfname");      unlink("$dfname");
             &logthis("Delayed $cmd to $conserver: >$answer<");              &logthis("Delayed $cmd: >$answer<");
             &logperm("S:$conserver:$bcmd");              &logperm("S:$conserver:$bcmd");
         }                  }        
     } @allbuffered;      }
   
 # ------------------------------------------------------- Listen to UNIX socket  # ------------------------------------------------------- Listen to UNIX socket
   &status("Opening socket");
 unless (  unless (
   $server = IO::Socket::UNIX->new(Local  => $port,    $server = IO::Socket::UNIX->new(Local  => $port,
                                   Type   => SOCK_STREAM,                                    Type   => SOCK_STREAM,
Line 365  unless ( Line 300  unless (
        my $st=120+int(rand(240));         my $st=120+int(rand(240));
        &logthis(         &logthis(
          "<font color=blue>WARNING: ".           "<font color=blue>WARNING: ".
          "Can't make server socket $conserver ($st secs): $@</font>");           "Can't make server socket ($st secs): $@</font>");
        sleep($st);         sleep($st);
        exit;          exit; 
      };       };
Line 394  while (1) { Line 329  while (1) {
     # check for new information on the connections we have      # check for new information on the connections we have
   
     # anything to read or accept?      # anything to read or accept?
     foreach $client ($select->can_read(1)) {      foreach $client ($select->can_read(0.1)) {
   
         if ($client == $server) {          if ($client == $server) {
             # accept a new connection              # accept a new connection
               &status("Accept new connection: $conserver");
             $client = $server->accept();              $client = $server->accept();
             $select->add($client);              $select->add($client);
             nonblock($client);              nonblock($client);
Line 413  while (1) { Line 348  while (1) {
                 delete $outbuffer{$client};                  delete $outbuffer{$client};
                 delete $ready{$client};                  delete $ready{$client};
   
                   &status("Idle");
                 $select->remove($client);                  $select->remove($client);
                 close $client;                  close $client;
                 next;                  next;
Line 441  while (1) { Line 377  while (1) {
         next unless exists $outbuffer{$client};          next unless exists $outbuffer{$client};
   
         $rv = $client->send($outbuffer{$client}, 0);          $rv = $client->send($outbuffer{$client}, 0);
   
         unless ($outbuffer{$client} eq "con_lost\n") {
         unless (defined $rv) {          unless (defined $rv) {
             # Whine, but move on.              # Whine, but move on.
             warn "I was told I could write, but I can't.\n";              &logthis("I was told I could write, but I can't.\n");
             next;              next;
         }          }
           $errno=$!;
         if (($rv == length $outbuffer{$client}) ||          if (($rv == length $outbuffer{$client}) ||
             ($! == POSIX::EWOULDBLOCK)) {              ($errno == POSIX::EWOULDBLOCK) || ($errno == 0)) {
             substr($outbuffer{$client}, 0, $rv) = '';              substr($outbuffer{$client}, 0, $rv) = '';
             delete $outbuffer{$client} unless length $outbuffer{$client};              delete $outbuffer{$client} unless length $outbuffer{$client};
         } else {          } else {
             # Couldn't write all the data, and it wasn't because              # Couldn't write all the data, and it wasn't because
             # it would have blocked.  Shutdown and move on.              # it would have blocked.  Shutdown and move on.
   
       &logthis("Dropping data with ".$errno.": ".
                        length($outbuffer{$client}).", $rv");
   
             delete $inbuffer{$client};              delete $inbuffer{$client};
             delete $outbuffer{$client};              delete $outbuffer{$client};
             delete $ready{$client};              delete $ready{$client};
Line 461  while (1) { Line 404  while (1) {
             close($client);              close($client);
             next;              next;
         }          }
         } else {
   # -------------------------------------------------------- Wow, connection lost
            &logthis(
        "<font color=red>CRITICAL: Closing connection</font>");
    &status("Connection lost");
            $remotesock->shutdown(2);
            &logthis("Attempting to open new connection");
            &openremote($conserver);          
         }
     }      }
      
 }  }
 }  }
   
Line 478  sub handle { Line 431  sub handle {
 # ============================================================= Process request  # ============================================================= Process request
         # $request is the text of the request          # $request is the text of the request
         # put text of reply into $outbuffer{$client}          # put text of reply into $outbuffer{$client}
   # ------------------------------------------------------------ Is this the end?
           if ($request eq "close_connection_exit\n") {
       &status("Request close connection");
              &logthis(
        "<font color=red>CRITICAL: Request Close Connection</font>");
              $remotesock->shutdown(2);
              $server->close();
              exit;
           }
 # -----------------------------------------------------------------------------  # -----------------------------------------------------------------------------
         if ($request =~ /^encrypt\:/) {          if ($request =~ /^encrypt\:/) {
     my $cmd=$request;      my $cmd=$request;
Line 492  sub handle { Line 454  sub handle {
             }              }
             $request="enc:$cmdlength:$encrequest\n";              $request="enc:$cmdlength:$encrequest\n";
         }          }
   # --------------------------------------------------------------- Main exchange
       $SIG{ALRM}=sub { die "timeout" };
       $SIG{__DIE__}='DEFAULT';
       eval {
           alarm(300);
           &status("Sending: $request");
         print $remotesock "$request";          print $remotesock "$request";
           &status("Waiting for reply from $conserver: $request");
         $answer=<$remotesock>;          $answer=<$remotesock>;
           &status("Received reply: $request");
           alarm(0);
       };
       if ($@=~/timeout/) { 
          $answer='';
          &logthis(
           "<font color=red>CRITICAL: Timeout: $request</font>");
       }  
       $SIG{ALRM}='DEFAULT';
       $SIG{__DIE__}=\&catchexception;
   
   
         if ($answer) {          if ($answer) {
    if ($answer =~ /^enc/) {     if ($answer =~ /^enc/) {
                my ($cmd,$cmdlength,$encinput)=split(/:/,$answer);                 my ($cmd,$cmdlength,$encinput)=split(/:/,$answer);
Line 512  sub handle { Line 493  sub handle {
            $outbuffer{$client} .= "con_lost\n";             $outbuffer{$client} .= "con_lost\n";
         }          }
   
        &status("Completed: $request");
   
 # ===================================================== Done processing request  # ===================================================== Done processing request
     }      }
     delete $ready{$client};      delete $ready{$client};
Line 532  sub nonblock { Line 515  sub nonblock {
             or die "Can't make socket nonblocking: $!\n";              or die "Can't make socket nonblocking: $!\n";
 }  }
   
   
   sub openremote {
   # ---------------------------------------------------- Client to network server
   
       my $conserver=shift;
   
   &status("Opening TCP");
   
   unless (
     $remotesock = IO::Socket::INET->new(PeerAddr => $hostip{$conserver},
                                         PeerPort => $perlvar{'londPort'},
                                         Proto    => "tcp",
                                         Type     => SOCK_STREAM)
      ) { 
          my $st=120+int(rand(240));
          &logthis(
   "<font color=blue>WARNING: Couldn't connect ($st secs): $@</font>");
          sleep($st);
          exit; 
        };
   # ----------------------------------------------------------------- Init dialog
   
   &status("Init dialogue: $conserver");
   
        $SIG{ALRM}=sub { die "timeout" };
        $SIG{__DIE__}='DEFAULT';
        eval {
            alarm(60);
   print $remotesock "init\n";
   $answer=<$remotesock>;
   print $remotesock "$answer";
   $answer=<$remotesock>;
   chomp($answer);
             alarm(0);
        };
        $SIG{ALRM}='DEFAULT';
        $SIG{__DIE__}=\&catchexception;
    
        if ($@=~/timeout/) {
    &logthis("Timed out during init");
            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; 
   }
   
   sleep 5;
   &status("Ponging");
   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;
   }
   
   }
   
   
   
   # 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 [$@]</font>");
       die($@);
   }
   
   # -------------------------------------- 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 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 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");
       %childatt=();
       &checkchildren();
   }
   
   # -------------------------------------------------- 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";
   
   
       $SIG{ALRM}=sub { die "timeout" };
       $SIG{__DIE__}='DEFAULT';
       eval {
        alarm(10);
        print $sclient "$cmd\n";
        $answer=<$sclient>;
        chomp($answer);
        alarm(0);
       };
       if ((!$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";
   }
   
   
   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;
   }
   
   
   
   # ----------------------------------- 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.
   
   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.
   
   =item *
   
   SIGCHLD
   
   Parent signal assignment:
    $SIG{CHLD} = \&REAPER;
   
   Child signal assignment:
    none
   
   Command-line invocations:
    B<kill> B<-s> SIGCHLD I<PID>
   
   Subroutine B<REAPER>:
    This is only invoked for the B<lonc> parent I<PID>.
   Information pertaining to the child is removed.
   The socket port is cleaned up.
   
   =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
Removed from v.1.14  
changed lines
  Added in v.1.31

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